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what you 're looking at is n't some weird x-ray . it 's actually a baby yellow tang surgeonfish at two months old . and you thought your childhood was awkward . but here is the same fish as an adult , a beautiful inhabitant of the indian and pacific oceans ' coral reefs and one of the most popular captive fish for salt water aquariums . of the 27,000 known fish species , over a quarter live on coral reefs that make up less than 1 % of the earth 's surface . but prior to settling down in this diverse tropical environment , baby coral reef fish face the difficult process of growing up on their own , undergoing drastic changes , and the journey of a lifetime before they find that reef to call home . the life cycle for most of these fish begins when their parents spew sperm and eggs into the water column . this can happen daily , seasonally , or yearly depending on the species , generally following lunar or seasonal tidal patterns . left to their fate , the fertilized eggs drift with the currents , and millions of baby larvae hatch into the world . when they first emerge , the larvae are tiny and vulnerable . some do n't even have gills yet and must absorb oxygen directly from the water through their tissue-thin skin . they may float in the water column anywhere from minutes to months , sometimes drifting thousands of miles across vast oceans , far from the reefs where they were born . along the way , they must successfully avoid predators , obtain food , and ride the right currents to find their way to a suitable adult habitat , which might as well be a needle in vast haystack of ocean . so , how did they accomplish this feat ? until recently , marine biologists thought of larval fish as largely passive drifters , dispersed by ocean currents to distant locales . but in the last 20 years , new research has suggested that larvae may not be as helpless as they seem , and are capable of taking their fate in their own fins to maximize their chances of survival . the larvae of many species are unexpectedly strong swimmers , and can move vertically in the water column to place themselves in different water masses and preferentially ride certain currents . these fish may be choosing the best routes to their eventual homes . when searching for these homes , evidence suggests that larvae navigate via a complex suite of sensory systems , detecting both sound and smell . odor , in particular , allows larvae to distinguish between different environments , even adjacent reefs , helping guide them toward their preferred adult habitats . many will head for far-flung locales miles away from their birth place . but some will use smell and other sensory cues to navigate back to the reefs where they were born , even if they remain in the larval stage for months . so , what happens when larvae do find a suitable coral reef ? do they risk it all in one jump from the water column , hoping to land in exactly the right spot to settle down and metamorphose into adults ? not exactly . instead , larvae appear to have more of a bungee system . larvae will drop down in the water column to check out a reef below . if conditions are n't right , they can jump back up into higher water masses and ride on , chancing that the next reef they find will be a better fit . but this is the point where our knowledge ends . we do n't know the geographic movements of individual larva for most species . nor do we know which exact environmental cues and behaviors they use to navigate to the reefs they will call home . but we do know that these tiny trekkers are more than the fragile and helpless creatures science once believed them to be . the secret lives of baby fish remain largely mysterious to us , unknown adventures waiting to be told .
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but some will use smell and other sensory cues to navigate back to the reefs where they were born , even if they remain in the larval stage for months . so , what happens when larvae do find a suitable coral reef ? do they risk it all in one jump from the water column , hoping to land in exactly the right spot to settle down and metamorphose into adults ?
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today , over half of the world ’ s reefs are threatened by human activities . how do you think the complex early life of coral reef fish might complicate reef conservation ?
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translator : ido dekkers reviewer : ariana bleau lugo say you 're at the beach , and you get sand in your eyes . how do you know the sand is there ? you obviously ca n't see it , but if you are a normal , healthy human , you can feel it , that sensation of extreme discomfort , also known as pain . now , pain makes you do something , in this case , rinse your eyes until the sand is gone . and how do you know the sand is gone ? exactly . because there 's no more pain . there are people who do n't feel pain . now , that might sound cool , but it 's not . if you ca n't feel pain , you could get hurt , or even hurt yourself and never know it . pain is your body 's early warning system . it protects you from the world around you , and from yourself . as we grow , we install pain detectors in most areas of our body . these detectors are specialized nerve cells called nociceptors that stretch from your spinal cord to your skin , your muscles , your joints , your teeth and some of your internal organs . just like all nerve cells , they conduct electrical signals , sending information from wherever they 're located back to your brain . but , unlike other nerve cells , nociceptors only fire if something happens that could cause or is causing damage . so , gently touch the tip of a needle . you 'll feel the metal , and those are your regular nerve cells . but you wo n't feel any pain . now , the harder you push against the needle , the closer you get to the nociceptor threshold . push hard enough , and you 'll cross that threshold and the nociceptors fire , telling your body to stop doing whatever you 're doing . but the pain threshold is n't set in stone . certain chemicals can tune nociceptors , lowering their threshold for pain . when cells are damaged , they and other nearby cells start producing these tuning chemicals like crazy , lowering the nociceptors ' threshold to the point where just touch can cause pain . and this is where over-the-counter painkillers come in . aspirin and ibuprofen block production of one class of these tuning chemicals , called prostaglandins . let 's take a look at how they do that . when cells are damaged , they release a chemical called arachidonic acid . and two enzymes called cox-1 and cox-2 convert this arachidonic acid into prostaglandin h2 , which is then converted into a bunch of other chemicals that do a bunch of things , including raise your body temperature , cause inflammation and lower the pain threshold . now , all enzymes have an active site . that 's the place in the enzyme where the reaction happens . the active sites of cox-1 and cox-2 fit arachidonic acid very cozily . as you can see , there is no room to spare . now , it 's in this active site that aspirin and ibuprofen do their work . so , they work differently . aspirin acts like a spine from a porcupine . it enters the active site and then breaks off , leaving half of itself in there , totally blocking that channel and making it impossible for the arachidonic acid to fit . this permanently deactivates cox-1 and cox-2 . ibuprofen , on the other hand , enters the active site , but does n't break apart or change the enzyme . cox-1 and cox-2 are free to spit it out again , but for the time that that ibuprofen is in there , the enzyme ca n't bind arachidonic acid , and ca n't do its normal chemistry . but how do aspirin and ibuprofen know where the pain is ? well , they do n't . once the drugs are in your bloodstream , they are carried throughout your body , and they go to painful areas just the same as normal ones . so that 's how aspirin and ibuprofen work . but there are other dimensions to pain . neuropathic pain , for example , is pain caused by damage to our nervous system itself ; there does n't need to be any sort of outside stimulus . and scientists are discovering that the brain controls how we respond to pain signals . for example , how much pain you feel can depend on whether you 're paying attention to the pain , or even your mood . pain is an area of active research . if we can understand it better , maybe we can help people manage it better .
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once the drugs are in your bloodstream , they are carried throughout your body , and they go to painful areas just the same as normal ones . so that 's how aspirin and ibuprofen work . but there are other dimensions to pain .
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why might aspirin and ibuprofen reduce fever ?
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many modern musical instruments are cumbersome or have a lot of parts . some need a stand or a stool . but the cajon is a drum , a stand and a seat all in one convenient box . and this simplicity may be key to its journey across continents and cultures to become one of the most popular percussion instruments in the world today . the cajon 's story begins in west africa , whose indigenousness people had rich musical traditions centered on drumming and dancing . when many of them were captured and brought to the americas as slaves , they brought this culture with them , but without their native instruments , they had to improvise . african slaves in coastal peru did n't have the materials or the opportunity to craft one of their traditional drums such as a djembe or a djun djun . but what they did have were plenty of shipping crates . not only were these readily accessible , but their inconspicuous appearance may have helped get around laws prohibiting slaves from playing music . early peruvian cajons consisted of a simple box with five thick wooden sides . the sixth side , made of a thinner sheet of wood , would be used as the striking surface , or more commonly known as the tapa . a sound hole was also cut into the back to allow the sound to escape . as an afro-peruvian culture developed , and new forms of music and dance , such as zamacueca , festejo and landó were born , the cajon became a dedicated musical instrument in its own right . early modifications involved simply bending the planks of the box to tweak the sound , and when abolition of slavery introduced the cajon to a broader population , more improvisation and experimentation soon followed . perhaps the person most responsible for introducing the cajon to european audiences was spanish flamenco guitarist paco de lucía . when touring in peru in 1977 , he and his percussionist rubem dantas discovered the cajon and brought it back to spain , recognizing its potential for use in flamenco music . by stretching guitar strings along the inside of the tapa , the flamenco musicians were able to create a buzz-like snare sound . combined with the regular base tone , this gave the cajon a sound close to a basic drum set . the cajon quickly caught on , not only becoming standard in flamenco , but being used in genres like folk , jazz , blues and rock . today , many specialized cajons are manufactured , some with adjustable strings , some with multiple playing surfaces , and some with a snare mechansim . but the basic concept remains the same , and the story of the cajon shows that the simplest things can have the most amazing potential when you think outside and inside the box .
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and this simplicity may be key to its journey across continents and cultures to become one of the most popular percussion instruments in the world today . the cajon 's story begins in west africa , whose indigenousness people had rich musical traditions centered on drumming and dancing . when many of them were captured and brought to the americas as slaves , they brought this culture with them , but without their native instruments , they had to improvise .
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what south american culture are we talking about when we discuss the story of the cajon ?
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translator : andrea mcdonough reviewer : bedirhan cinar our earth is a collection of puzzle pieces that make up the universe . in the vast darkness of space , the universe is lit by stars , which could one day become a supernova and create all the puzzle pieces that we know today as the elements . all elements were formed and released into space by exploding stars . for centuries , humans have tried to discover what makes up the world around them . little did they know that all the pieces they needed were right under their noses . the discovery of these pieces revolutionized our understanding of the world and allowed for the creation of what might be the greatest gift to science : the periodic table . so , where are these elements , and how do we find a means to order them ? well , believe it or not , ancient civilizations were very much aware of many elements around them , but they did not identify them as the pieces of our universe . elements like gold , silver , and copper were easily spotted by ancient cultures , and were used for multiple purposes like jewelry and tools . why were these elements spotted so easily ? think of the periodic table as a puzzle . the corner pieces are edges of a puzzle , are generally the easiest to find and place because they stand out with their smooth edges , and clearly do n't interlock with other puzzle pieces . like puzzle pieces , elements can be choosy on who they interact with . some like to react with other elements , while others do not . the elements that do not interact with other elements are easy to pin-point , while the ones who like to interact with others are difficult to find . gold , silver , and copper are some of the choosier elements so we can find them easier . so let 's fast forward to the late 1600 's where hennig brand , a german alchemist , was busy working in his laboratory . like many other alchemists of his time , brand was trying to extract gold from the human body . brand hit upon what he thought was the most obvious answer to his problem : urine . urine is gold in coloration and could perhaps have gold in it . so , brand collected as much urine as he possibly could , much of it being his own , then he decided to boil it down in hopes of obtaining gold . so brand boiled his , well , urine , down until he collected a paste and heated the paste to a very high temperature . eventually smoke appeared and the material burned brightly and violently . brand had unknowingly isolated phosphorous from his urine . it was the first time anyone had discovered an element , but he did n't really understand what he had done . at the time of brand , the concept of element had not been discovered . instead ancient greek principles of objects being composed of earth , water , air , and fire were predominant . it was n't until the work of antoine lavoisier , who is now known as the father of chemistry , that science defined what an element was . lavoisier defined an element as a substance that can not be broken down by existing chemical means . lavoisier created a list of the known elements of his time and tried to put the elements in some sort of order in which they could be classified , such as gases or metals . he was the first one to try to put the puzzle together . this was just the beginning of a means to organize the known elements of his time . many other chemists then came along to make the puzzle clearer . one of them , john dalton , weighed the elements and arranged the puzzle by weight . german chemist wolfgang döbereiner later combined elements to see how they reacted with one another . what he found was that certain elements shared similar properties and reactions . for example , when pure lithium , sodium , and potassium are exposed to water , they will react violently and skid across the surface of the water with sparks . the scientists then realized that these similiarities are no coincidence : elements belong to families that share similar properties . but the chemist who finally put the puzzle together is dmitri mendeleev . he created cards of each known element and tried to order them based on atomic weight and their known properties . the story is that he stayed up 3 days and 3 nights , and he finally fell into a deep sleep and he dreamed about a table to order the elements . mendeleev was not only able to create the periodic table , but he was able to predict elements that were not yet discovered . the puzzle of the periodic table of the elements was solved .
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the elements that do not interact with other elements are easy to pin-point , while the ones who like to interact with others are difficult to find . gold , silver , and copper are some of the choosier elements so we can find them easier . so let 's fast forward to the late 1600 's where hennig brand , a german alchemist , was busy working in his laboratory .
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what did hennig brand use to try to find gold ?
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translator : andrea mcdonough reviewer : bedirhan cinar when we think about learning , we often picture students in a classroom or lecture hall , books open on their desks , listening intently to a teacher or professor in the front of the room . but in psychology , learning means something else . to psychologists , learning is a long-term change in behavior that 's based on experience . two of the main types of learning are called classical conditioning and operant , or instrumental , conditioning . let 's talk about classical conditioning first . in the 1890 's , a russian physiologist named ivan pavlov did some really famous experiments on dogs . he showed dogs some food and rang a bell at the same time . after a while , the dogs would associate the bell with the food . they would learn that when they heard the bell , they would get fed . eventually , just ringing the bell made the dogs salivate . they learned to expect food at the sound of a bell . you see , under normal conditions , the sight and smell of food causes a dog to salivate . we call the food an unconditioned stimulus , and we call salivation the unconditioned response . nobody trains a dog to salivate over some steak . however , when we pair an unconditioned stimulus like food with something that was previously neutral , like the sound of a bell , that neutral stimulus becomes a conditioned stimulus . and so classical conditioning was discovered . we see how this works with animals , but how does it work with humans ? in exactly the same way . let 's say that one day you go to the doctor to get a shot . she says , `` do n't worry , this wo n't hurt a bit , '' and then gives you the most painful shot you 've ever had . a few weeks later you go to the dentist for a check-up . he starts to put a mirror in your mouth to examine your teeth , and he says , `` do n't worry , this wo n't hurt a bit . '' even though you know the mirror wo n't hurt , you jump out of the chair and run , screaming from the room . when you went to get a shot , the words , `` this wo n't hurt a bit , '' became a conditioned stimulus when they were paired with pain of the shot , the unconditioned stimulus , which was followed by your conditioned response of getting the heck out of there . classical conditioning in action . operant conditioning explains how consequences lead to changes in voluntary behavior . so how does operant conditioning work ? there are two main components in operant conditioning : reinforcement and punishment . reinforcers make it more likely that you 'll do something again , while punishers make it less likely . reinforcement and punishment can be positive or negative , but this does n't mean good and bad . positive means the addition of a stimulus , like getting dessert after you finish your veggies , and negative means the removal of a stimulus , like getting a night of no homework because you did well on an exam . let 's look at an example of operant conditioning . after eating dinner with your family , you clear the table and wash the dishes . when you 're done , your mom gives you a big hug and says , `` thank you for helping me . '' in this situation , your mom 's response is positive reinforcement if it makes you more likely to repeat the operant response , which is to clear the table and wash the dishes . operant conditioning is everywhere in our daily lives . there are n't many things we do that have n't been influenced at some point by operant conditioning . we even see operant conditioning in some extraordinary situations . one group of scientists showed the power of operant conditioning by teaching pigeons to be art connoisseurs . using food as a positive reinforcer , scientists have taught pigeons to select paintings by monet over those by picasso . when showed works of other artists , scientists observed stimulus generalization as the pigeons chose the impressionists over the cubists . maybe next they 'll condition the pigeons to paint their own masterpieces .
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nobody trains a dog to salivate over some steak . however , when we pair an unconditioned stimulus like food with something that was previously neutral , like the sound of a bell , that neutral stimulus becomes a conditioned stimulus . and so classical conditioning was discovered .
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what is stimulus generalization ?
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translator : andrea mcdonough reviewer : jessica ruby welcome to the department of plagiarism investigation . the d.p.i . has dealt with numerous complex cases in their effort to bring plagiarists to justice and to rescue purloined texts . the first form of plagiarism that the d.p.i . regularly encounters is known as brain child snatching , in honor of the latin word , plagiarius , from which plagiarism originates . brain child snatchers sneak up on innocent papers and copy and paste them without citing any sources , putting quotation marks around direct quotes or changing a word . they 've also been known to steal and hold particularly eloquent essays for ransom . when brain child snatchers get together , they form a kidnapping ring , which involves brain child snatching from multiple sources . some perpetrators have even been known to commit self-plagiarism , one of the laziest crimes in the annals of the d.p.i . also known as one-sided collaborators , these odd balls snatch up entire texts or small passages that they 've written before and present them as brand-new material . brain child snatchers and kidnapping rings are easy for the d.p.i . to catch . just paste a few passages into a search engine , and bam ! they 're caught red-handed . the more covert forms of plagiarism include the wild goose chase technique , in which plagiarists create fake authors , book titles , page numbers , or other information in order to cover up plagiarism . and the old synonym switcheroo in which plagiarists utilize a thesaurus as their main weapon . by substituting a synonym for nearly every word in the document and leaving the sentence structure and order of the ideas the same , plagiarists give legitimate paraphrasing a very bad name . shoddy paraphrasing is also a key part of variations on a smokescreen , a technique in which multiple passages are paraphrased , then pasted together into one . the thorniest issue that the d.p.i . deals with is the misconception that you can never be accused of plagiarism if you use quotes and cite your sources . this is most certainly not the case because a paper that is made up of passage upon passage of other people 's ideas is known as a wholly quotable document . this is considered plagiarism since there are no original thoughts in the work . similarly , passage after passage of too closely paraphrased text from multiple cited sources is also plagiarism of the pervasively paraphrased kind because the ideas still are n't one 's own . and lastly , the technique of revealing while concealing is plagiarism because it involves selective amnesia regarding one 's sources in an attempt to cover up wholly quotable and pervasively paraphrased issues in a text . some passages are meticulously documented , quoted , or paraphrased , while others are presented entirely as one 's own . as you can see , the d.p.i . has its hands full , tackling all sorts of academic mischief and mayhem , ranging from the petty to the outrageous . given the gravity of these transgressions , you might be wondering why you 've never heard of the department of plagiarism investigation 's victories . that 's because it does n't technically exist . but people , like you and me , can be our own d.p.i . agents to fight plagiarism and uphold the values of original thinking . we know that the best defense against plagiarism consists of writers who save themselves time , worry , and effort by taking the far easier road of just doing the work themselves .
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this is most certainly not the case because a paper that is made up of passage upon passage of other people 's ideas is known as a wholly quotable document . this is considered plagiarism since there are no original thoughts in the work . similarly , passage after passage of too closely paraphrased text from multiple cited sources is also plagiarism of the pervasively paraphrased kind because the ideas still are n't one 's own . and lastly , the technique of revealing while concealing is plagiarism because it involves selective amnesia regarding one 's sources in an attempt to cover up wholly quotable and pervasively paraphrased issues in a text .
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suppose that in the previous example mary had included no quotes , but she had paraphrased almost every line in the paper and properly cited it . would this also be considered plagiarism ?
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ok , so thulium is a very expensive lanthanide . it ’ s very expensive because it ’ s very hard to separate it from its neighbours . the lanthanides from the left to right undergo this contraction where they get smaller and smaller and over on the right-hand-side at this point that they are all of a very similar size . now we can separate them now but it is quite difficult to do and therefore quite expensive , so thulium is not used very often . however thulium , as well as being able to obtain the plus-3 oxidation state , it is also one of those ones which can obtain the plus-2 oxidation state , which means that chemists are now beginning to find uses for it which they hadn ’ t expected before . so you may see the use of thulium increase in years to come . because it ’ s very hard to isolate because it ’ s of a very similar size to its neighbours , it took a guy called charles james , in 1911 , a famous 15,000 times of recrystalization to isolate thulium in a pure , albeit as a chloride , but a pure nonetheless , compound for the first time .
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ok , so thulium is a very expensive lanthanide . it ’ s very expensive because it ’ s very hard to separate it from its neighbours .
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why is thulium very expensive ?
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ladies and gentlemen , at ted we talk a lot about leadership and how to make a movement . so let 's watch a movement happen , start to finish , in under three minutes and dissect some lessons from it . first , of course you know , a leader needs the guts to stand out and be ridiculed . what he 's doing is so easy to follow . here 's his first follower with a crucial role ; he 's going to show everyone else how to follow . now , notice that the leader embraces him as an equal . now it 's not about the leader anymore ; it 's about them , plural . now , there he is calling to his friends . now , if you notice that the first follower is actually an underestimated form of leadership in itself . it takes guts to stand out like that . the first follower is what transforms a lone nut into a leader . ( laughter ) ( applause ) and here comes a second follower . now it 's not a lone nut , it 's not two nuts -- three is a crowd , and a crowd is news . so a movement must be public . it 's important to show not just the leader , but the followers , because you find that new followers emulate the followers , not the leader . now , here come two more people , and immediately after , three more people . now we 've got momentum . this is the tipping point . now we 've got a movement . ( laughter ) so , notice that , as more people join in , it 's less risky . so those that were sitting on the fence before now have no reason not to . they wo n't stand out , they wo n't be ridiculed , but they will be part of the in-crowd if they hurry . ( laughter ) so , over the next minute , you 'll see all of those that prefer to stick with the crowd because eventually they would be ridiculed for not joining in . and that 's how you make a movement . but let 's recap some lessons from this . so first , if you are the type , like the shirtless dancing guy that is standing alone , remember the importance of nurturing your first few followers as equals so it 's clearly about the movement , not you . ( laughter ) okay , but we might have missed the real lesson here . the biggest lesson , if you noticed -- did you catch it ? -- is that leadership is over-glorified . yes , it was the shirtless guy who was first , and he 'll get all the credit , but it was really the first follower that transformed the lone nut into a leader . so , as we 're told that we should all be leaders , that would be really ineffective . if you really care about starting a movement , have the courage to follow and show others how to follow . and when you find a lone nut doing something great , have the guts to be the first one to stand up and join in . and what a perfect place to do that , at ted . thanks . ( applause )
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so a movement must be public . it 's important to show not just the leader , but the followers , because you find that new followers emulate the followers , not the leader . now , here come two more people , and immediately after , three more people .
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why do we need to be followers instead of just leaders ? why does it take guts ?
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a national hero ? or public enemy number one ? historical figures are often controversial , but few were as deified or vilified in their lifetime as the seventh president of the united states . this is history vs. andrew jackson . `` order , order , hm , uh , what were we ... ah yes , mr. jackson ! you stand accused of degrading the office of the presidency , causing financial collapse and wanton cruelty against american indians . how do you plead ? '' `` now , your honor , i am not a big city lawyer , but i do know a few things . and i know that president jackson was a self-made frontiersman , a great general , a real man of the people . '' `` your honor , this 'man of the people ' was a gambler , a drunk , and a brawler . why , i 've heard it said that he would fight at the drop of the hat and then drop the hat himself . i ask you , was such a man fit for the most distinguished office in the nation ? can we forget the debacle of his inauguration ? who ever heard of inviting a drunken mob into the white house ? it took ages to get the upholstery clean . '' `` that drunken mob , sir , was the american people , and they deserve to celebrate their victory . '' `` order , order ! now , did this celebration have pie ? '' `` very well . mr. jackson , is it not the case that immediately upon assuming office you introduced the spoils system , replacing hundreds of perfectly good federal employees with incompetent party loyalists ? '' `` your honor , the president did no such thing . he tried to institute rotation in office to avoid any profiteering or funny business . it was the rest of the party who insisted on giving posts to their lackeys . '' `` but mr. jackson complied , did he not ? '' `` now , uh , see here . '' `` moving on . mr. jackson , did you not help to cause the financial panic of 1837 , and the ensuing economic depression with your obsessive war against the bank of the united states ? was not vetoing its reauthorization , as you did in 1832 , an act of irresponsible populace pandering that made no economic sense ? '' `` your honor , the gentleman has quite the imagination . that bank was just a way for rich yanks to get richer . and all that money panic was caused when british banks raised interest rates and cut lending . to blame it on the president is preposterous , i say . '' `` but if mr. jackson had not destroyed the national bank , it would have been able to lend to farmers and businesses when other credit dried up , would it not ? '' `` hm , this is all highly speculative . can we move on ? '' `` certainly , your honor . we now come to mr. jackson 's most terrible offense : forcing entire tribes out of their native lands via the indian removal act . '' `` i resent that accusation , sir . the u.s. of a. bought that land from the indians fair and square . '' `` do you call coercion and threats by a nation with a far more powerful army fair and square ? or signing a treaty for removing the cherokee with a small group that did n't include their actual leaders ? they did n't have time to properly supply themselves before the army came and forced them to march the trail of tears . '' `` now , hold on a minute . this was all van buren 's doing after president jackson left office . '' `` but mr. jackson laid the groundwork and made sure the treaty was ratified . all president van buren had to do afterwards was enforce it . '' `` look here , your honor . our government 's been purchasing indian land since the beginning , and my client was negotiating these deals even before he was president . president jackson truly believed it was best for the indians to get compensated for their land and move out west , where there was plenty of space for them to keep living the way they were accustomed , rather than stick around and keep butting heads with the white settlers . some of whom , i remind our court , wanted to exterminate them outright . it was a different time . '' `` and yet , even in this different time , there were many in congress and even the supreme court who saw how wrong the removal act was and loudly opposed it , were there not ? '' `` my client was under a great deal of pressure . i say , do you think it 's easy governing such a huge country and keeping the union together , when states are fixing to nullify federal laws ? president jackson barely got south carolina to back down over those import tariffs , and then georgia had to go discover gold and start grabbing up cherokee land . it was either get the indians to move or get in another fight with a state government . '' `` so , you admit that mr. jackson sacrified moral principles to achieve some political goals ? '' `` i do declare , show me one leader who has n't . '' as societies change and morals evolve , yesterday 's hero may become tomorrow 's villain , or vice versa . history may be past , but our understanding of it is always on trial .
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`` very well . mr. jackson , is it not the case that immediately upon assuming office you introduced the spoils system , replacing hundreds of perfectly good federal employees with incompetent party loyalists ? '' `` your honor , the president did no such thing . he tried to institute rotation in office to avoid any profiteering or funny business .
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the “ spoils system ” refers to when a newly elected president ________ .
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looking up at the night sky , we are amazed by how it seems to go on forever . but what will the sky look like billions of years from now ? a particular type of scientist , called a cosmologist , spends her time thinking about that very question . the end of the universe is intimately linked to what the universe contains . over 100 years ago , einstein developed the theory of general relativity , formed of equations that help us understand the relationship between what a universe is made of and its shape . it turns out that the universe could be curved like a ball or sphere . we call this positively curved or closed . or it could be shaped like a saddle . we call this negatively curved or open . or it could be flat . and that shape determines how the universe will live and die . we now know that the universe is very close to flat . however , the components of the universe can still affect its eventual fate . we can predict how the universe will change with time if we measure the amounts or energy densities of the various components in the universe today . so , what is the universe made of ? the universe contains all the things that we can see , like stars , gas , and planets . we call these things ordinary or baryonic matter . even though we see them all around us , the total energy density of these components is actually very small , around 5 % of the total energy of the universe . so , now let 's talk about what the other 95 % is . just under 27 % of the rest of the energy density of the universe is made up of what we call dark matter . dark matter is only very weakly interacting with light , which means it does n't shine or reflect light in the way that stars and planets do , but , in every other way , it behaves like ordinary matter -- it attracts things gravitationally . in fact , the only way we can detect this dark matter is through this gravitational interaction , how things orbit around it and how it bends light as it curves the space around it . we have yet to discover a dark matter particle , but scientists all over the world are searching for this elusive particle or particles and the effects of dark matter on the universe . but this still does n't add up to 100 % . the remaining 68 % of the energy density of the universe is made up of dark energy , which is even more mysterious than dark matter . this dark energy does n't behave like any other substance we know at all and acts more like anti-gravity force . we say that it has a gravitational pressure , which ordinary matter and dark matter do not . instead of pulling the universe together , as we would expect gravity to do , the universe appears to be expanding apart at an ever-increasing rate . the leading idea for dark energy is that it is a cosmological constant . that means it has the strange property that it expands as the volume of space increases to keep its energy density constant . so , as the universe expands as it is doing right now , there will be more and more dark energy . dark matter and baryonic matter , on the other hand , do n't expand with the universe and become more diluted . because of this property of the cosmological constant , the future universe will be more and more dominated by dark energy , becoming colder and colder and expanding faster and faster . eventually , the universe will run out of gas to form stars , and the stars themselves will run out of fuel and burn out , leaving the universe with only black holes in it . given enough time , even these black holes will evaporate , leaving a universe that is completely cold and empty . that is what we call the heat death of the universe . while it might sound depressing living in a universe that will end its lifetime cold and devoid of life , the end fate of our universe actually has a beautiful symmetry to its hot , fiery beginning . we call the accelerating end state of the universe a de sitter phase , named after the dutch mathematician willem de sitter . however , we also believe that the universe had another phase of de sitter expansion in the earliest times of its life . we call this early period inflation , where , shortly after the big bang , the universe expanded extremely fast for a brief period . so , the universe will end in much the same state as it began , accelerating . we live at an extraordinary time in the life of the universe where we can start to understand the universe 's journey and view a history that plays itself out on the sky for all of us to see .
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or it could be flat . and that shape determines how the universe will live and die . we now know that the universe is very close to flat .
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what do we think the shape of the universe is ?
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what rights do people have , and where do they come from ? who gets to make decisions for others and on what authority ? and how can we organize society to meet people 's needs ? these questions challenged an entire nation during the upheaval of the french revolution . by the end of the 18th century , europe had undergone a profound intellectual and cultural shift known as the enlightenment . philosophers and artists promoted reason and human freedom over tradition and religion . the rise of a middle class and printed materials encouraged political awareness , and the american revolution had turned a former english colony into an independent republic . yet france , one of the largest and richest countries in europe was still governed by an ancient regime of three rigid social classes called estates . the monarch king louis xvi based his authority on divine right and granted special privileges to the first and second estates , the catholic clergy , and the nobles . the third estate , middle class merchants and craftsmen , as well as over 20 million peasants , had far less power and they were the only ones who paid taxes , not just to the king , but to the other estates as well . in bad harvest years , taxation could leave peasants with almost nothing while the king and nobles lived lavishly on their extracted wealth . but as france sank into debt due to its support of the american revolution and its long-running war with england , change was needed . king louis appointed finance minister jacques necker , who pushed for tax reforms and won public support by openly publishing the government 's finances . but the king 's advisors strongly opposed these initiatives . desperate for a solution , the king called a meeting of the estates-general , an assembly of representatives from the three estates , for the first time in 175 years . although the third estate represented 98 % of the french population , its vote was equal to each of the other estates . and unsurprisingly , both of the upper classes favored keeping their privileges . realizing they could n't get fair representation , the third estate broke off , declared themselves the national assembly , and pledged to draft a new constitution with or without the other estates . king louis ordered the first and second estates to meet with the national assembly , but he also dismissed necker , his popular finance minister . in response , thousands of outraged parisians joined with sympathetic soldiers to storm the bastille prison , a symbol of royal power and a large storehouse of weapons . the revolution had begun . as rebellion spread throughout the country , the feudal system was abolished . the assembly 's declaration of the rights of man and citizen proclaimed a radical idea for the time -- that individual rights and freedoms were fundamental to human nature and government existed only to protect them . their privileges gone , many nobles fled abroad , begging foreign rulers to invade france and restore order . and while louis remained as the figurehead of the constitutional monarchy , he feared for his future . in 1791 , he tried to flee the country but was caught . the attempted escape shattered people 's faith in the king . the royal family was arrested and the king charged with treason . after a trial , the once-revered king was publicly beheaded , signaling the end of one thousand years of monarchy and finalizing the september 21st declaration of the first french republic , governed by the motto `` liberté , égalité , fraternité . '' nine months later , queen marie antoinette , a foreigner long-mocked as `` madame déficit '' for her extravagant reputation , was executed as well . but the revolution would not end there . some leaders , not content with just changing the government , sought to completely transform french society -- its religion , its street names , even its calendar . as multiple factions formed , the extremist jacobins lead by maximilien robespierre launched a reign of terror to suppress the slightest dissent , executing over 20,000 people before the jacobin 's own downfall . meanwhile , france found itself at war with neighboring monarchs seeking to strangle the revolution before it spread . amidst the chaos , a general named napoleon bonaparte took charge , becoming emperor as he claimed to defend the revolution 's democratic values . all in all , the revolution saw three constitutions and five governments within ten years , followed by decades alternating between monarchy and revolt before the next republic formed in 1871 . and while we celebrate the french revolution 's ideals , we still struggle with many of the same basic questions raised over two centuries ago .
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the royal family was arrested and the king charged with treason . after a trial , the once-revered king was publicly beheaded , signaling the end of one thousand years of monarchy and finalizing the september 21st declaration of the first french republic , governed by the motto `` liberté , égalité , fraternité . '' nine months later , queen marie antoinette , a foreigner long-mocked as `` madame déficit '' for her extravagant reputation , was executed as well .
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how did the jacobins betray the ideals of liberté , égalité , and fraternité ?
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michael jordan once said , `` i do n't know whether i 'll fly or not . i know that when i 'm in the air sometimes i feel like i do n't ever have to come down . '' but thanks to isaac newton , we know that what goes up must eventually come down . in fact , the human limit on a flat surface for hang time , or the time from when your feet leave the ground to when they touch down again , is only about one second , and , yes , that even includes his airness , whose infamous dunk from the free throw line has been calculated at .92 seconds . and , of course , gravity is what 's making it so hard to stay in the air longer . earth 's gravity pulls all nearby objects towards the planet 's surface , accelerating them at 9.8 meters per second squared . as soon as you jump , gravity is already pulling you back down . using what we know about gravity , we can derive a fairly simple equation that models hang time . this equation states that the height of a falling object above a surface is equal to the object 's initial height from the surface plus its initial velocity multiplied by how many seconds it 's been in the air , plus half of the gravitational acceleration multiplied by the square of the number of seconds spent in the air . now we can use this equation to model mj 's free throw dunk . say mj starts , as one does , at zero meters off the ground , and jumps with an initial vertical velocity of 4.51 meters per second . let 's see what happens if we model this equation on a coordinate grid . since the formula is quadratic , the relationship between height and time spent in the air has the shape of a parabola . so what does it tell us about mj 's dunk ? well , the parabola 's vertex shows us his maximum height off the ground at 1.038 meters , and the x-intercepts tell us when he took off and when he landed , with the difference being the hang time . it looks like earth 's gravity makes it pretty hard for even mj to get some solid hang time . but what if he were playing an away game somewhere else , somewhere far ? well , the gravitational acceleration on our nearest planetary neighbor , venus , is 8.87 meters per second squared , pretty similar to earth 's . if michael jumped here with the same force as he did back on earth , he would be able to get more than a meter off the ground , giving him a hang time of a little over one second . the competition on jupiter with its gravitational pull of 24.92 meters per second squared would be much less entertaining . here , michael would n't even get a half meter off the ground , and would remain airborne a mere .41 seconds . but a game on the moon would be quite spectacular . mj could take off from behind half court , jumping over six meters high , and his hang time of over five and half seconds , would be long enough for anyone to believe he could fly .
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well , the parabola 's vertex shows us his maximum height off the ground at 1.038 meters , and the x-intercepts tell us when he took off and when he landed , with the difference being the hang time . it looks like earth 's gravity makes it pretty hard for even mj to get some solid hang time . but what if he were playing an away game somewhere else , somewhere far ?
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on earth , how high would a person have to jump to have a hang time of 1 second ? what would the equation of this jump look like ?
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i must look rather strange to you , all covered in spines , without even a face . but i 've taken many forms during my life . i started out just like you : a tiny egg in a watery world . my parents never knew each other . one moonlit night before a storm , thousands of urchins , clams and corals released trillions of sperm and eggs into the open sea . my father 's sperm somehow met my mother 's egg , and they fused . fertilization . instantly , i became an embryo the size of a speck of dust . after a few hours of drifting , i cleaved in two , then four , then eight cells . then so many , i lost count . in less than a day , i developed a gut and a skeleton . i became a rocket ship , a pluteus larva . i floated through the world of plankton , searching for tiny algae to eat . for weeks , i was surrounded by all kinds of organisms , larvae of all sorts . most are so different from their adult form that biologists have a tough time figuring out who they are . try matching these youngsters to their parents . this veliger larvae will turn into a snail ; this zoea , into a crab ; and this planula , into a clytia jelly . some of my young companions are easier to picture as grown-ups . these baby jellies , known as ephyrae , already resemble their beautiful but deadly parents . here in the plankton , there 's more than one way to get your genes into the next generation . most medusa jellies make special structures called polyps , that simply bud off babies with no need for sex . salps are similar . when food is abundant , they just clone themselves into long chains . the plankton is full of surprises when it comes to sex . meet the hermaphrodites . these comb jellies and arrow worms produce , store and release both sperm and eggs . they can fertilize themselves , or another . when you 're floating in a vast sea , with little control over who you may meet , it can pay to play both sides of the field . the majority of species here , however , never mate , nor form any sort of lasting bonds . that was my parents ' strategy . there were so many of us pluteus larvae , i just hid in the crowd , while most of my kin were devoured . not all parents leave the survival of their offspring to chance . some have far fewer young and take much better care of them , brooding their precious cargo for days , even months . this speedy copepod totes her beautifully packaged eggs for days . this phronima crustacean carries her babies on her chest , then carefully places them in a gelatinous barrel . but the black-eyed squid takes the prize . she cradles her eggs in long arms for nine months , the same time it takes to gestate a human infant . eventually , all youngsters have to make it on their own in this drifting world . some will spend their whole lives in the plankton , but others , like me , move on . a few weeks after i was conceived , i decided to settle down , and metamorphosed into a recognizable urchin . so now you know a bit of my story . i may just be a slow-moving ball of spines , but do n't let my calm adult exterior fool you . i was a rocket ship . i was a wild child .
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then so many , i lost count . in less than a day , i developed a gut and a skeleton . i became a rocket ship , a pluteus larva .
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how long did it take for the plankton to develop a gut and a skeleton ?
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here 's what has to happen for pregnancy to occur after sexual intercourse . sperm must swim up the vagina , through the cervical opening , upwards through the uterus , and into one of the two fallopian tubes . if an egg , released during that month 's ovulation , is in the tube , one sperm has a chance to fertilize it . contraceptives are designed to prevent this process , and they work in three basic ways . they block the sperm , disable sperm before they reach the uterus , or suppress ovulation . block is the simplest . male and female condoms prevent sperm from coming into contact with the vaginal space . that barrier is also why they , unlike other contraceptive methods , are able to prevent transmission of certain sexually transmitted diseases . meanwhile , the diaphragm , cervical cap , and sponge work by being placed over the cervix , barricading the entrance to the uterus . these contraceptives are sometimes called barrier methods and can be used with spermicides , an example of the second category , disable . a spermicide is a chemical that immobilizes and destroys sperm . today 's spermicides come as foam , cream , jelly , suppositories , and even a thin piece of translucent film that dissolves in the vagina . these products can be inserted directly into the vagina before intercourse , or can be combined with block methods , like a diaphragm or condom , for added proection . the third category for preventing pregnancy works by suppressing the action of an egg maturing in the ovary . if there is n't an egg available in the fallopian tube , there 's nothing for sperm to fertilize . hormonal contraceptives , including the pill , the patch , the depo shot , and the vaginal ring all release synthetic versions of various combinations of progesterone and estrogen . this hormone cocktail suppresses ovulation , keeping the immature egg safely sequestered in the ovary . synthetic progesterone also has a block trick up its sleeve . it makes cervical mucus too thick and sticky for sperm to swim through easily . there are other contraceptives that use multiple approaches at the same time . for example , many iuds , or intrauterine devices , contain synthetic hormones which suppress ovulation . some also contain copper , which disable sperm while also making egg implantation in the uterus difficult . block , disable , or suppress : is one strategy better than the other ? there are differences , but a lot of it has to do with how convenient and easy it is to use each contraceptive correctly . for example , male condoms would be about 98 % effective if everyone used them perfectly . that 98 % means if 100 couples correctly used condoms for a year , two women would get pregnant . but not everyone uses them correctly , so they 're only 82 % effective in practice . other methods , like the patch and pill , are 99 % effective when they 're used perfectly . but in practice , that 's 91 % . spermicide is only 85 % effective , even with perfect usage , and just 71 % effective with typical usage . another important consideration in the choice of contraceptives are side effects , which almost exclusively affect women rather than men . hormonal methods in particular can cause symptoms like headaches , nausea , and high blood pressure , but they vary from woman to woman . that 's why these methods require a prescription from a doctor . the choice of contraceptive method is a personal one , and what works best for you now may change later . scientists also continue to research new methods , such as a male pill that would prevent sperm production . in the meantime , there are quite a few options to block sperm , disable them , or suppress eggs and keep them out of reach .
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here 's what has to happen for pregnancy to occur after sexual intercourse . sperm must swim up the vagina , through the cervical opening , upwards through the uterus , and into one of the two fallopian tubes .
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what has to happen before pregnancy can occur ?
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in the winter of 1995 , scientists pointed the hubble telescope at an area of the sky near the big dipper , a spot that was dark and out of the way of light pollution from surrounding stars . the location was apparently empty , and the whole endeavor was risky . what , if anything , was going to show up ? over ten consecutive days , the telescope took close to 150 hours of exposure of that same area . and what came back was nothing short of spectacular : an image of over 1,500 distinct galaxies glimmering in a tiny sliver of the universe . now , let 's take a step back to understand the scale of this image . if you were to take a ballpoint pen and hold it at arm 's length in front of the night sky , focusing on its very tip , that is what the hubble telescope captured in its first deep field image . in other words , those 3,000 galaxies were seen in just a tiny speck of the universe , approximately one two-millionth of the night sky . to put all this in perspective , the average human measures about 1.7 meters . with earth 's diameter at 12,700 kilometers , that 's nearly 7.5 million humans lined up head to toe . the apollo 8 astronauts flew a distance of 380,000 kilometers to the moon . and our relatively small sun has a diameter of about 1.4 million kilometers , or 110 times the earth 's diameter . a step further , the milky way holds somewhere between 100 to 400 billion stars , including our sun . and each glowing dot of a galaxy captured in the deep field image contains billions of stars at the very least . almost a decade after taking the deep field image , scientists adjusted the optics on the hubble telescope and took another long exposure over a period of about four months . this time , they observed 10,000 galaxies . half of these galaxies have since been analyzed more clearly in what 's known as the extreme deep field image , or xdf . by combining over ten years of photographs , the xdf shows galaxies so distant that they 're only one ten-billionth the brightness that the human eye can perceive . so , what can we learn about the universe from the deep field images ? in a study of the universe , space and time are inextricably linked . that 's because of the finite speed of light . so the deep field images are like time machines to the ancient universe . they reach so far into space and time that we can observe galaxies that existed over 13 billion years ago . this means we 're looking at the universe as it was less than a billion years after the big bang , and it allows scientists to research galaxies in their infancy . the deep field images have also shown that the universe is homogeneous . that is , images taken at different spots in the sky look similar . that 's incredible when we think about how vast the universe is . why would we expect it to be the same across such huge distances ? on the scale of a galaxy , let alone the universe , we 're smaller than we can readily comprehend , but we do have the capacity to wonder , to question , to explore , to investigate , and to imagine . so the next time you stand gazing up at the night sky , take a moment to think about the enormity of what is beyond your vision , out in the dark spaces between the stars .
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this time , they observed 10,000 galaxies . half of these galaxies have since been analyzed more clearly in what 's known as the extreme deep field image , or xdf . by combining over ten years of photographs , the xdf shows galaxies so distant that they 're only one ten-billionth the brightness that the human eye can perceive .
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the first hubble ultra deep field image showed 1500 galaxies total , but how many were seen in the upgraded hubble extreme deep field image ?
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once upon a time , south america lived harmoniously alongside africa until a crack in the earth drove the two continents apart . this breakup began about 200 million years ago during the separation of the supercontinent known as pangaea . their proximity back then explains why the same plant fossils and reptile fossils , like the mesosaurus , can be found on the south american east coast and african west coast . however , this evidence does not account for how the continents moved apart . for that , we 'll need to take a close look at the earth below our feet . though you may not realize it , the ground below you is traveling across the earth at a rate of about 10 cm/year , or the speed at which your fingernails grow . this is due to plate tectonics , or the large-scale movement of earth 's continents . the motion occurs within the top two layers of the earth 's mantle , the lithosphere and asthenosphere . the lithosphere , which includes the crust and uppermost mantle , comprises the land around you . beneath the lithosphere is the asthenosphere the highly viscous but solid rock portion of the upper mantle . it 's between 80 and 200 km below the earth 's surface . while the asthenosphere wraps around the earth 's core as one connected region , the lithosphere is separated on top into tectonic plates . there are seven primary tectonic plates that compose the shape of the planet we know today . like the other smaller tectonic plates , the primary plates are about 100 km thick and are composed of one or two layers : continental crust and oceanic crust . continental crust forms the continents and areas of shallow water close to their shores , whereas oceanic crust forms the ocean basins . the transition from the granitic continental crust to the basaltic oceanic crust occurs beyond the continentel shelf , in which the shore suddenly slopes down towards the ocean floor . the south american plate is an example of a tectonic plate made of two crusts : the continent we know from today 's map and a large region of the atlantic ocean around it . collectively comprising the lithosphere , these plates are brittler and stiffer than the heated , malleable layer of the asthenosphere below . because of this , the tectonic plates float on top of this layer , independently of one another . the speed and direction in which these tectonic plates move depends on the temperature and pressure of the asthenosphere below . scientists are still trying to nail down the driving forces behind this movement , with some theories pointing towards mantle convection , while others are examining the influence of the earth 's rotation and gravitational pull . though the mechanics have not been sorted out , the scientific community agrees that our tectonic plates are moving and have been for billions of years . because these plates move independently , a fair amount of pushing and pulling between the plates occurs . the first type of interaction is a divergent boundary , in which two plates move away from one another . we see this in the mid-atlantic ridge between south america and africa . the next interaction is when two plates collide , known as a convergent boundary . in this instance , the land is pushed upward to form large mountain ranges , like the himalayas . in fact , the indian plate is still colliding with the eurasian plate , which is why mount everest grows one cm/year . finally , there 's the transform boundaries , where two plates scrape past one another . the grinding of the transform boundary leads to many earthquakes , which is what happens in the 810 mile-long san andreas fault . the moving earth is unstoppable , and , while a shift of 10 cm/year may not seem like a lot , over millions of years our planet will continue to dramatically change . mountains will rise , shorelines will recede , islands will pop up . in fact , one projected map shows the cities of los angeles and san francisco on top of each other . maybe south america and africa will come together again , too . only time will tell .
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however , this evidence does not account for how the continents moved apart . for that , we 'll need to take a close look at the earth below our feet . though you may not realize it , the ground below you is traveling across the earth at a rate of about 10 cm/year , or the speed at which your fingernails grow .
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how did the peak of mt . everest rise from sea level to 8,848 feet ?
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translator : andrea mcdonough reviewer : bedirhan cinar about 100 days ago , we landed a two-ton suv on the surface of another planet , on the surface of mars . this is one of the first pictures we took there with our rover , looking out at mount sharp . i kind of cry a little bit , choke up , when i see this picture . why mars and why do we look at these other planets ? part of it is to understand our own planet -- what 's the context for us ? we live on this amazing planet , but mars is a lot like earth . it 's similar in size . during the daytime , it can get up to 70 degrees fahrenheit . so , it 's so like earth , but at the same time , this is a barren landscape . you do n't see any trees , you do n't see any cactuses growing , anything like that . today i 'm going to tell you about how we got from earth to mars and why it 's so cool . so one of the things we start with is a blank sheet of paper . we knew from the previous missions in 2004 , spirit and opportunity , there was water on mars in the past . but what 's the next step ? we 're looking for an even more fundamental level of , what does it take to have life survive ? and so , to have that kind of knowledge and understanding , we have to carry a mass amount of instruments . we have to carry the kind of labs that people have whole rooms devoted to on earth inside of , essentially , a small car . and we shrunk it all down to something that weighs about as much as i do , and then put it inside of this rover that weighs as much as your car does . and that rover is now on the surface of mars , but it 's so heavy , and so it kind of takes a special challenge for us to make it all work and come together . so we look at our tool of , what do we have to land stuff on mars ? and one of the options is airbags . we 've done it before . airbags are pretty cool , they bounce around a lot . you could never put a human inside of an airbag , because they would get squashed . but the problem with airbags is , the airbags you see here , which landed the smaller rover -- it 's like 400 pounds , the entire rover -- were about the size of this room . so you can imagine the size of airbags it would take to land a two-ton rover on mars . and they 'd have to be made out of materials that do n't even exist today , so it 'd be some kind of exotic material that we 'd have to develop and it may or may not work . so , what about rockets ? you know , you see all the rocket ships landing in old movies , all rockets on the bottom -- it 's a cool idea . it works when they 're pretty light still , but the problem is , these rockets have to be pretty strong to actually softly land you on mars . and so they would be so powerful they could dig holes into the ground and then you would just end up inside of a hole and not be able to drive out of it . so , not the best design . but what if i could take the rockets and move them up ? and that 's what we came up with . it 's a rocket-powered jet pack ; we call it the sky crane . basically , this big rocket sits on top of our rover and when we 're ready to land , the rocket hovers in place and we slowly lower the rover to the ground . and then we touch down , we 're actually on the wheels , we 're ready to drive , day one . but in addition to that , the scientists were like , `` we actually want to go somewhere interesting . '' the last two missions were cool , but they basically landed in what was like landing in the plains or desert . not very exciting . we all know from the exciting places on earth like the grand canyon , those are , for the scientists , the most interesting , because you see that whole layer , you see years and years of history all in one place . the same thing is true for where we landed . we wanted to land somewhere that was unique , that had this crater wall where things had been dug up for us , where mountains were pushing things up . but the problem is , if you landed with the older systems , you could 've landed on the side of that mountain and just tumbled off , could 've been the side of a cliff , the crater wall or a large boulder . so we needed a kind of technology to help us land in a very small area , and that was this little guided entry from apollo . we took it from the 1960s . we flew over like the manned vehicle , because they have to pick up men , you ca n't just land all over the place . and then we landed , like , spot-on in the middle . and in fact , it was so spot-on that when we did it , it was basically like a quarterback launching towards mars -- like a quarterback , though , that was in seattle , throwing at a receiver that was moving here in giants stadium . that 's how accurate we were . kind of awesome . but you only get one shot , and so we actually have to design a system that we can build and test and operate , and so it 's not just about can we get it to mars , but , if it 's only one chance , how do you make sure that one chance goes well ? so there 's all these processes to make sure things are built properly . then we go out to the desert and drive around and test it . we fly things in f-18s to make sure the radar systems work in high speeds . then , most importantly , we test the team to make sure they know how to operate it . we do n't want to miss it because we sent the wrong command and now it 's going to be rebooting forever . so , that guy fred there , he did a lot of that . and then we launched it on this rocket to mars . we landed 2,000 pounds on mars , but the entire thing was about 10,000 pounds when we lifted off from earth , all the fuel and the solar arrays and everything else that we needed . and , again , we were so accurate that we landed in this , like , little pin-point on mars . in the meantime , though , we had to design a landing system that worked . and i told you about the actual physics of it , but here 's the catch : mars is about 14 minutes away from earth in light speed , which means if i try to control it with a joystick , i would be always controlling to 14 minutes in advance , so it would n't work . so we had to give it all the smarts and knowledge it needed to make it happen . so we built in all these smarts and algorithms and told it here 's what you 're going to have to do , and it goes from basically five times the speed of a speeding bullet to about a baby 's crawl , all within about seven minutes , which are called the seven minutes of terror , because i was about to throw up . ( laughter ) but today we 're on the surface of mars , and this was one of the panoramas we took a couple days after we landed , and it 's amazing to me , because you look at this , and can see the grand canyon , you can see your own planet , you can imagine walking on the surface . and so what we 're going to do and continue to do is to understand what makes mars so special and what makes earth even more special that we 're all here together today . so we 'll see where curiosity takes us -- not just our rover , but our sense of exploration . thank you . ( applause )
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so we had to give it all the smarts and knowledge it needed to make it happen . so we built in all these smarts and algorithms and told it here 's what you 're going to have to do , and it goes from basically five times the speed of a speeding bullet to about a baby 's crawl , all within about seven minutes , which are called the seven minutes of terror , because i was about to throw up . ( laughter ) but today we 're on the surface of mars , and this was one of the panoramas we took a couple days after we landed , and it 's amazing to me , because you look at this , and can see the grand canyon , you can see your own planet , you can imagine walking on the surface .
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ferdowsi 's team had to `` build-in all these smarts and algorithms '' in order to account for what he called the seven minutes of terror . for what exactly were they adjusting ?
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good morning . how are you ? ( laughter ) it 's been great , has n't it ? i 've been blown away by the whole thing . in fact , i 'm leaving . ( laughter ) there have been three themes running through the conference which are relevant to what i want to talk about . one is the extraordinary evidence of human creativity in all of the presentations that we 've had and in all of the people here . just the variety of it and the range of it . the second is that it 's put us in a place where we have no idea what 's going to happen , in terms of the future . no idea how this may play out . i have an interest in education . actually , what i find is everybody has an interest in education . do n't you ? i find this very interesting . if you 're at a dinner party , and you say you work in education -- actually , you 're not often at dinner parties , frankly . ( laughter ) if you work in education , you 're not asked . ( laughter ) and you 're never asked back , curiously . that 's strange to me . but if you are , and you say to somebody , you know , they say , `` what do you do ? '' and you say you work in education , you can see the blood run from their face . they 're like , `` oh my god , '' you know , `` why me ? '' ( laughter ) `` my one night out all week . '' ( laughter ) but if you ask about their education , they pin you to the wall . because it 's one of those things that goes deep with people , am i right ? like religion , and money and other things . so i have a big interest in education , and i think we all do . we have a huge vested interest in it , partly because it 's education that 's meant to take us into this future that we ca n't grasp . if you think of it , children starting school this year will be retiring in 2065 . nobody has a clue , despite all the expertise that 's been on parade for the past four days , what the world will look like in five years ' time . and yet we 're meant to be educating them for it . so the unpredictability , i think , is extraordinary . and the third part of this is that we 've all agreed , nonetheless , on the really extraordinary capacities that children have -- their capacities for innovation . i mean , sirena last night was a marvel , was n't she ? just seeing what she could do . and she 's exceptional , but i think she 's not , so to speak , exceptional in the whole of childhood . what you have there is a person of extraordinary dedication who found a talent . and my contention is , all kids have tremendous talents . and we squander them , pretty ruthlessly . so i want to talk about education and i want to talk about creativity . my contention is that creativity now is as important in education as literacy , and we should treat it with the same status . ( applause ) thank you . ( applause ) that was it , by the way . thank you very much . ( laughter ) so , 15 minutes left . ( laughter ) well , i was born ... no . ( laughter ) i heard a great story recently -- i love telling it -- of a little girl who was in a drawing lesson . she was six , and she was at the back , drawing , and the teacher said this girl hardly ever paid attention , and in this drawing lesson , she did . the teacher was fascinated . she went over to her , and she said , `` what are you drawing ? '' and the girl said , `` i 'm drawing a picture of god . '' and the teacher said , `` but nobody knows what god looks like . '' and the girl said , `` they will , in a minute . '' ( laughter ) when my son was four in england -- actually , he was four everywhere , to be honest . ( laughter ) if we 're being strict about it , wherever he went , he was four that year . he was in the nativity play . do you remember the story ? ( laughter ) no , it was big , it was a big story . mel gibson did the sequel , you may have seen it . ( laughter ) `` nativity ii . '' but james got the part of joseph , which we were thrilled about . we considered this to be one of the lead parts . we had the place crammed full of agents in t-shirts : `` james robinson is joseph ! '' ( laughter ) he did n't have to speak , but you know the bit where the three kings come in ? they come in bearing gifts , gold , frankincense and myrrh . this really happened . we were sitting there and i think they just went out of sequence , because we talked to the little boy afterward and we said , `` you ok with that ? '' and he said , `` yeah , why ? was that wrong ? '' they just switched . the three boys came in , four-year-olds with tea towels on their heads , and they put these boxes down , and the first boy said , `` i bring you gold . '' and the second boy said , `` i bring you myrrh . '' and the third boy said , `` frank sent this . '' ( laughter ) what these things have in common is that kids will take a chance . if they do n't know , they 'll have a go . am i right ? they 're not frightened of being wrong . i do n't mean to say that being wrong is the same thing as being creative . what we do know is , if you 're not prepared to be wrong , you 'll never come up with anything original -- if you 're not prepared to be wrong . and by the time they get to be adults , most kids have lost that capacity . they have become frightened of being wrong . and we run our companies like this . we stigmatize mistakes . and we 're now running national education systems where mistakes are the worst thing you can make . and the result is that we are educating people out of their creative capacities . picasso once said this , he said that all children are born artists . the problem is to remain an artist as we grow up . i believe this passionately , that we do n't grow into creativity , we grow out of it . or rather , we get educated out of it . so why is this ? i lived in stratford-on-avon until about five years ago . in fact , we moved from stratford to los angeles . so you can imagine what a seamless transition that was . ( laughter ) actually , we lived in a place called snitterfield , just outside stratford , which is where shakespeare 's father was born . are you struck by a new thought ? i was . you do n't think of shakespeare having a father , do you ? do you ? because you do n't think of shakespeare being a child , do you ? shakespeare being seven ? i never thought of it . i mean , he was seven at some point . he was in somebody 's english class , was n't he ? ( laughter ) how annoying would that be ? ( laughter ) `` must try harder . '' ( laughter ) being sent to bed by his dad , you know , to shakespeare , `` go to bed , now ! and put the pencil down . '' ( laughter ) `` and stop speaking like that . '' ( laughter ) `` it 's confusing everybody . '' ( laughter ) anyway , we moved from stratford to los angeles , and i just want to say a word about the transition . my son did n't want to come . i 've got two kids ; he 's 21 now , my daughter 's 16 . he did n't want to come to los angeles . he loved it , but he had a girlfriend in england . this was the love of his life , sarah . he 'd known her for a month . ( laughter ) mind you , they 'd had their fourth anniversary , because it 's a long time when you 're 16 . he was really upset on the plane , he said , `` i 'll never find another girl like sarah . '' and we were rather pleased about that , frankly -- ( laughter ) because she was the main reason we were leaving the country . ( laughter ) but something strikes you when you move to america and travel around the world : every education system on earth has the same hierarchy of subjects . every one . does n't matter where you go . you 'd think it would be otherwise , but it is n't . at the top are mathematics and languages , then the humanities , and at the bottom are the arts . everywhere on earth . and in pretty much every system too , there 's a hierarchy within the arts . art and music are normally given a higher status in schools than drama and dance . there is n't an education system on the planet that teaches dance everyday to children the way we teach them mathematics . why ? why not ? i think this is rather important . i think math is very important , but so is dance . children dance all the time if they 're allowed to , we all do . we all have bodies , do n't we ? did i miss a meeting ? ( laughter ) truthfully , what happens is , as children grow up , we start to educate them progressively from the waist up . and then we focus on their heads . and slightly to one side . if you were to visit education , as an alien , and say `` what 's it for , public education ? '' i think you 'd have to conclude , if you look at the output , who really succeeds by this , who does everything that they should , who gets all the brownie points , who are the winners -- i think you 'd have to conclude the whole purpose of public education throughout the world is to produce university professors . is n't it ? they 're the people who come out the top . and i used to be one , so there . ( laughter ) and i like university professors , but you know , we should n't hold them up as the high-water mark of all human achievement . they 're just a form of life , another form of life . but they 're rather curious , and i say this out of affection for them . there 's something curious about professors in my experience -- not all of them , but typically , they live in their heads . they live up there , and slightly to one side . they 're disembodied , you know , in a kind of literal way . they look upon their body as a form of transport for their heads . ( laughter ) do n't they ? it 's a way of getting their head to meetings . ( laughter ) if you want real evidence of out-of-body experiences , get yourself along to a residential conference of senior academics , and pop into the discotheque on the final night . ( laughter ) and there , you will see it . grown men and women writhing uncontrollably , off the beat . ( laughter ) waiting until it ends so they can go home and write a paper about it . ( laughter ) our education system is predicated on the idea of academic ability . and there 's a reason . around the world , there were no public systems of education , really , before the 19th century . they all came into being to meet the needs of industrialism . so the hierarchy is rooted on two ideas . number one , that the most useful subjects for work are at the top . so you were probably steered benignly away from things at school when you were a kid , things you liked , on the grounds that you would never get a job doing that . is that right ? do n't do music , you 're not going to be a musician ; do n't do art , you wo n't be an artist . benign advice -- now , profoundly mistaken . the whole world is engulfed in a revolution . and the second is academic ability , which has really come to dominate our view of intelligence , because the universities designed the system in their image . if you think of it , the whole system of public education around the world is a protracted process of university entrance . and the consequence is that many highly-talented , brilliant , creative people think they 're not , because the thing they were good at at school was n't valued , or was actually stigmatized . and i think we ca n't afford to go on that way . in the next 30 years , according to unesco , more people worldwide will be graduating through education than since the beginning of history . more people , and it 's the combination of all the things we 've talked about -- technology and its transformation effect on work , and demography and the huge explosion in population . suddenly , degrees are n't worth anything . is n't that true ? when i was a student , if you had a degree , you had a job . if you did n't have a job , it 's because you did n't want one . and i did n't want one , frankly . ( laughter ) but now kids with degrees are often heading home to carry on playing video games , because you need an ma where the previous job required a ba , and now you need a phd for the other . it 's a process of academic inflation . and it indicates the whole structure of education is shifting beneath our feet . we need to radically rethink our view of intelligence . we know three things about intelligence . one , it 's diverse . we think about the world in all the ways that we experience it . we think visually , we think in sound , we think kinesthetically . we think in abstract terms , we think in movement . secondly , intelligence is dynamic . if you look at the interactions of a human brain , as we heard yesterday from a number of presentations , intelligence is wonderfully interactive . the brain is n't divided into compartments . in fact , creativity -- which i define as the process of having original ideas that have value -- more often than not comes about through the interaction of different disciplinary ways of seeing things . by the way , there 's a shaft of nerves that joins the two halves of the brain called the corpus callosum . it 's thicker in women . following off from helen yesterday , this is probably why women are better at multi-tasking . because you are , are n't you ? there 's a raft of research , but i know it from my personal life . if my wife is cooking a meal at home -- which is not often , thankfully . ( laughter ) no , she 's good at some things , but if she 's cooking , she 's dealing with people on the phone , she 's talking to the kids , she 's painting the ceiling , she 's doing open-heart surgery over here . if i 'm cooking , the door is shut , the kids are out , the phone 's on the hook , if she comes in i get annoyed . i say , `` terry , please , i 'm trying to fry an egg in here . '' ( laughter ) `` give me a break . '' ( laughter ) actually , do you know that old philosophical thing , if a tree falls in a forest and nobody hears it , did it happen ? remember that old chestnut ? i saw a great t-shirt recently , which said , `` if a man speaks his mind in a forest , and no woman hears him , is he still wrong ? '' ( laughter ) and the third thing about intelligence is , it 's distinct . i 'm doing a new book at the moment called `` epiphany , '' which is based on a series of interviews with people about how they discovered their talent . i 'm fascinated by how people got to be there . it 's really prompted by a conversation i had with a wonderful woman who maybe most people have never heard of , gillian lynne . have you heard of her ? some have . she 's a choreographer , and everybody knows her work . she did `` cats '' and `` phantom of the opera . '' she 's wonderful . i used to be on the board of the royal ballet , as you can see . anyway , gillian and i had lunch one day and i said , `` how did you get to be a dancer ? '' it was interesting . when she was at school , she was really hopeless . and the school , in the '30s , wrote to her parents and said , `` we think gillian has a learning disorder . '' she could n't concentrate ; she was fidgeting . i think now they 'd say she had adhd . would n't you ? but this was the 1930s , and adhd had n't been invented at this point . it was n't an available condition . ( laughter ) people were n't aware they could have that . ( laughter ) anyway , she went to see this specialist . so , this oak-paneled room , and she was there with her mother , and she was led and sat on this chair at the end , and she sat on her hands for 20 minutes while this man talked to her mother about the problems gillian was having at school . because she was disturbing people ; her homework was always late ; and so on , little kid of eight . in the end , the doctor went and sat next to gillian , and said , `` i 've listened to all these things your mother 's told me , i need to speak to her privately . wait here . we 'll be back ; we wo n't be very long , '' and they went and left her . but as they went out of the room , he turned on the radio that was sitting on his desk . and when they got out , he said to her mother , `` just stand and watch her . '' and the minute they left the room , she was on her feet , moving to the music . and they watched for a few minutes and he turned to her mother and said , `` mrs. lynne , gillian is n't sick ; she 's a dancer . take her to a dance school . '' i said , `` what happened ? '' she said , `` she did . i ca n't tell you how wonderful it was . we walked in this room and it was full of people like me . people who could n't sit still . people who had to move to think . '' who had to move to think . they did ballet , they did tap , jazz ; they did modern ; they did contemporary . she was eventually auditioned for the royal ballet school ; she became a soloist ; she had a wonderful career at the royal ballet . she eventually graduated from the royal ballet school , founded the gillian lynne dance company , met andrew lloyd webber . she 's been responsible for some of the most successful musical theater productions in history , she 's given pleasure to millions , and she 's a multi-millionaire . somebody else might have put her on medication and told her to calm down . ( applause ) what i think it comes to is this : al gore spoke the other night about ecology and the revolution that was triggered by rachel carson . i believe our only hope for the future is to adopt a new conception of human ecology , one in which we start to reconstitute our conception of the richness of human capacity . our education system has mined our minds in the way that we strip-mine the earth : for a particular commodity . and for the future , it wo n't serve us . we have to rethink the fundamental principles on which we 're educating our children . there was a wonderful quote by jonas salk , who said , `` if all the insects were to disappear from the earth , within 50 years all life on earth would end . if all human beings disappeared from the earth , within 50 years all forms of life would flourish . '' and he 's right . what ted celebrates is the gift of the human imagination . we have to be careful now that we use this gift wisely and that we avert some of the scenarios that we 've talked about . and the only way we 'll do it is by seeing our creative capacities for the richness they are and seeing our children for the hope that they are . and our task is to educate their whole being , so they can face this future . by the way -- we may not see this future , but they will . and our job is to help them make something of it . thank you very much . ( applause )
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they all came into being to meet the needs of industrialism . so the hierarchy is rooted on two ideas . number one , that the most useful subjects for work are at the top .
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what two ideas were the hierarchy of subjects based upon ?
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so a few years ago , i did something really brave , or some would say really stupid . i ran for congress . for years , i had existed safely behind the scenes in politics as a fundraiser , as an organizer , but in my heart , i always wanted to run . the sitting congresswoman had been in my district since 1992 . she had never lost a race , and no one had really even run against her in a democratic primary . but in my mind , this was my way to make a difference , to disrupt the status quo . the polls , however , told a very different story . my pollsters told me that i was crazy to run , that there was no way that i could win . but i ran anyway , and in 2012 , i became an upstart in a new york city congressional race . i swore i was going to win . i had the endorsement from the new york daily news , the wall street journal snapped pictures of me on election day , and cnbc called it one of the hottest races in the country . i raised money from everyone i knew , including indian aunties that were just so happy an indian girl was running . but on election day , the polls were right , and i only got 19 percent of the vote , and the same papers that said i was a rising political star now said i wasted 1.3 million dollars on 6,321 votes . do n't do the math . it was humiliating . now , before you get the wrong idea , this is not a talk about the importance of failure . nor is it about leaning in . i tell you the story of how i ran for congress because i was 33 years old and it was the first time in my entire life that i had done something that was truly brave , where i did n't worry about being perfect . and i 'm not alone : so many women i talk to tell me that they gravitate towards careers and professions that they know they 're going to be great in , that they know they 're going to be perfect in , and it 's no wonder why . most girls are taught to avoid risk and failure . we 're taught to smile pretty , play it safe , get all a 's . boys , on the other hand , are taught to play rough , swing high , crawl to the top of the monkey bars and then just jump off headfirst . and by the time they 're adults , whether they 're negotiating a raise or even asking someone out on a date , they 're habituated to take risk after risk . they 're rewarded for it . it 's often said in silicon valley , no one even takes you seriously unless you 've had two failed start-ups . in other words , we 're raising our girls to be perfect , and we 're raising our boys to be brave . some people worry about our federal deficit , but i , i worry about our bravery deficit . our economy , our society , we 're just losing out because we 're not raising our girls to be brave . the bravery deficit is why women are underrepresented in stem , in c-suites , in boardrooms , in congress , and pretty much everywhere you look . in the 1980s , psychologist carol dweck looked at how bright fifth graders handled an assignment that was too difficult for them . she found that bright girls were quick to give up . the higher the iq , the more likely they were to give up . bright boys , on the other hand , found the difficult material to be a challenge . they found it energizing . they were more likely to redouble their efforts . what 's going on ? well , at the fifth grade level , girls routinely outperform boys in every subject , including math and science , so it 's not a question of ability . the difference is in how boys and girls approach a challenge . and it does n't just end in fifth grade . an hp report found that men will apply for a job if they meet only 60 percent of the qualifications , but women , women will apply only if they meet 100 percent of the qualifications . 100 percent . this study is usually invoked as evidence that , well , women need a little more confidence . but i think it 's evidence that women have been socialized to aspire to perfection , and they 're overly cautious . ( applause ) and even when we 're ambitious , even when we 're leaning in , that socialization of perfection has caused us to take less risks in our careers . and so those 600,000 jobs that are open right now in computing and tech , women are being left behind , and it means our economy is being left behind on all the innovation and problems women would solve if they were socialized to be brave instead of socialized to be perfect . ( applause ) so in 2012 , i started a company to teach girls to code , and what i found is that by teaching them to code i had socialized them to be brave . coding , it 's an endless process of trial and error , of trying to get the right command in the right place , with sometimes just a semicolon making the difference between success and failure . code breaks and then it falls apart , and it often takes many , many tries until that magical moment when what you 're trying to build comes to life . it requires perseverance . it requires imperfection . we immediately see in our program our girls ' fear of not getting it right , of not being perfect . every girls who code teacher tells me the same story . during the first week , when the girls are learning how to code , a student will call her over and she 'll say , `` i do n't know what code to write . '' the teacher will look at her screen , and she 'll see a blank text editor . if she did n't know any better , she 'd think that her student spent the past 20 minutes just staring at the screen . but if she presses undo a few times , she 'll see that her student wrote code and then deleted it . she tried , she came close , but she did n't get it exactly right . instead of showing the progress that she made , she 'd rather show nothing at all . perfection or bust . it turns out that our girls are really good at coding , but it 's not enough just to teach them to code . my friend lev brie , who is a professor at the university of columbia and teaches intro to java tells me about his office hours with computer science students . when the guys are struggling with an assignment , they 'll come in and they 'll say , `` professor , there 's something wrong with my code . '' the girls will come in and say , `` professor , there 's something wrong with me . '' we have to begin to undo the socialization of perfection , but we 've got to combine it with building a sisterhood that lets girls know that they are not alone . because trying harder is not going to fix a broken system . i ca n't tell you how many women tell me , `` i 'm afraid to raise my hand , i 'm afraid to ask a question , because i do n't want to be the only one who does n't understand , the only one who is struggling . when we teach girls to be brave and we have a supportive network cheering them on , they will build incredible things , and i see this every day . take , for instance , two of our high school students who built a game called tampon run -- yes , tampon run -- to fight against the menstruation taboo and sexism in gaming . or the syrian refugee who dared show her love for her new country by building an app to help americans get to the polls . or a 16-year-old girl who built an algorithm to help detect whether a cancer is benign or malignant in the off chance that she can save her daddy 's life because he has cancer . these are just three examples of thousands , thousands of girls who have been socialized to be imperfect , who have learned to keep trying , who have learned perseverance . and whether they become coders or the next hillary clinton or beyoncé , they will not defer their dreams . and those dreams have never been more important for our country . for the american economy , for any economy to grow , to truly innovate , we can not leave behind half our population . we have to socialize our girls to be comfortable with imperfection , and we 've got to do it now . we can not wait for them to learn how to be brave like i did when i was 33 years old . we have to teach them to be brave in schools and early in their careers , when it has the most potential to impact their lives and the lives of others , and we have to show them that they will be loved and accepted not for being perfect but for being courageous . and so i need each of you to tell every young woman you know -- your sister , your niece , your employee , your colleague -- to be comfortable with imperfection , because when we teach girls to be imperfect , and we help them leverage it , we will build a movement of young women who are brave and who will build a better world for themselves and for each and every one of us . thank you . ( applause ) thank you . chris anderson : reshma , thank you . it 's such a powerful vision you have . you have a vision . tell me how it 's going . how many girls are involved now in your program ? reshma saujani : yeah . so in 2012 , we taught 20 girls . this year we 'll teach 40,000 in all 50 states . ( applause ) and that number is really powerful , because last year we only graduated 7,500 women in computer science . like , the problem is so bad that we can make that type of change quickly . ca : and you 're working with some of the companies in this room even , who are welcoming graduates from your program ? rs : yeah , we have about 80 partners , from twitter to facebook to adobe to ibm to microsoft to pixar to disney , i mean , every single company out there . and if you 're not signed up , i 'm going to find you , because we need every single tech company to embed a girls who code classroom in their office . ca : and you have some stories back from some of those companies that when you mix in more gender balance in the engineering teams , good things happen . rs : great things happen . i mean , i think that it 's crazy to me to think about the fact that right now 85 percent of all consumer purchases are made by women . women use social media at a rate of 600 percent more than men . we own the internet , and we should be building the companies of tomorrow . and i think when companies have diverse teams , and they have incredible women that are part of their engineering teams , they build awesome things , and we see it every day . ca : reshma , you saw the reaction there . you 're doing incredibly important work . this whole community is cheering you on . more power to you . thank you . rs : thank you . ( applause )
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the bravery deficit is why women are underrepresented in stem , in c-suites , in boardrooms , in congress , and pretty much everywhere you look . in the 1980s , psychologist carol dweck looked at how bright fifth graders handled an assignment that was too difficult for them . she found that bright girls were quick to give up .
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what did carol dweck find when she studied bright fifth graders who were handed an assignment that was too difficult for them ?
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translator : tom carter reviewer : bedirhan cinar geckos and grasshoppers , worms and watermelons , elephants and escherichia coli , man and mushroom . all so different in form and function , but amazingly the same in how their form and function are determined . first , all these organisms are made of one or more cells , and every cell of every living thing on earth contains all the information it takes to create and duplicate and make variations of itself . that information is stored in a very long but quite simple double molecule called dna , or deoxyribonucleic acid . and the dna of every living organism is made of chains of four smaller molecules called nucleotides . what dictates the difference between a man and a mushroom is the sequence of these nucleotides in the long dna chain . the four differing nucleotide parts , called bases , are made of a few carbon , oxygen , hydrogen , nitrogen and phosphorus atoms , and the molecules look like this . and each of these four bases is attached to an identical backbone molecule , a sugar called deoxyribose - the `` d '' in dna - and a phosphate group . let 's simplify these nucleotides and show them like this . so , a single sequence of nucleotides joined by their common sugars would look like this . and the dna molecule where such sequences are stored looks like this . but how does a simple molecule dictate the form and function of millions of different living things ? you can think of dna as a great library of information , information that is used to do one thing and one thing only : direct the building of different protein molecules . and it 's the proteins that build the cells and keep them functioning and changing and reproducing . here 's where the familiar word 'gene ' comes in . if your dna is a library of information , a gene is a book in that library . a gene is a segment of the dna molecule . let 's say your body needs a particular protein , like insulin . to get it , some of your cells send a protein signal through the bloodstream to the cells in your pancreas , where insulin is made . that signal protein tells other proteins in the cell 's nuclei to open up a part of the dna double helix , the insulin gene , and start making insulin proteins . as soon as enough insulin has been produced , another signal protein comes to the pancreas ' cells that tells them to stop making insulin . it 's like looking up a book in the dna library about insulin , and then putting it back when you 're done . there are genes in dna for visible and invisible things that make up your body , like genes for eye color , protein pigments , for skin color , for hair color , for stopping and starting bone growth , for your blood type , for how many fingers or arms and legs you have , for proteins that influence how long you live . your dna probably contains between 25 thousand and 40 thousand genes , while the dna of a worm or a plant or a fruit fly contains about 12 thousand to 20 thousand genes . some of those genes have quite different sequences of nucleotides than yours , and some are similar to yours . though it happens infrequently , our own nucleotide sequences can change as the result of spontaneous or environmental damage which might remove or shift a nucleotide position . this changes the gene involved , and can then change the protein . most of these changes , called mutations , have very little effect on the organism or its descendants . some are mildly damaging , and a few can make the organism better-suited to its environment . it is these tiny changes in dna gene sequences , happening over millions of years , that create the differences among living organisms , from geckos to grasshoppers . worms to watermelons , elephants to escherichia coli , and man to mushroom .
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that information is stored in a very long but quite simple double molecule called dna , or deoxyribonucleic acid . and the dna of every living organism is made of chains of four smaller molecules called nucleotides . what dictates the difference between a man and a mushroom is the sequence of these nucleotides in the long dna chain .
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dna is made of chains of four smaller molecules called :
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translator : tom carter reviewer : bedirhan cinar ( zombie sounds ) doctor 1 : so , how did it get to be this way ? doctor 2 : well , it 's my professional opinion that the large gaping bite mark on its shoulder might have something to do with it . d1 : thanks . i mean , what causes its behavioral abnormalities ? d2 : well , we know all behaviors are rooted in the brain , so i 'd expect that something 's gone terribly wrong probably in there . d1 : thanks again , doctor obvious . let me be more specific . what changes in the brain would have to occur in order to cause this kind of behavior ? d2 : hmm . well , let 's see . the first thing i notice is how it moves . stiff legged , with long , lumbering steps , very slow and awkward . almost like what you 'd see in parkinson 's disease . maybe something 's wrong with his basal ganglia ? those are a collection of deep brain regions that regulate movement , through a neurochemical called dopamine . although most people think of dopamine as the `` happy '' chemical of the brain , the dopamine-containing neurons in the basal ganglia die off in parkinson 's disease , that 's what causes it . makes it more and more difficult to initiate actions . d1 : what ? look again at how it moves . stiff legs , long stance , these are n't parkinsonian movements , parkinson 's patients take short , shuffling steps , and the posture 's all wrong . this looks to me like what happens when the cerebellum is damaged . the cerebellum 's a little cauliflower-shaped area in the back of your head , but do n't let its size fool you . that little guy contains almost half of the neurons in the entire brain . patients who suffer degeneration from this region , something called spino-cerebellar ataxia , show a lack of coordination that results in stiff legs , wide stance , and a lumbering walk . my money 's on the cerebellum . d2 : touché . ok . so we 've nailed its motor problems . now what about that whole groaning , lack of talking thing ? d1 : hmm . you know , it sounds kind of like expressive aphasia , or broca 's aphasia , which makes producing words difficult . this is caused by damage to the inferior frontal gyrus , or possibly the anterior insula , both regions behind your temple on the left side of your head . d2 : i think you 're only half right . zombies definitely ca n't communicate , that 's for sure . but they do n't seem to do a good job of understanding things either . watch this . hey , walker ! your father smelt of elderberries ! ( laughs ) see ? no reaction . either it 's not a monty python fan , or it ca n't understand me . i 'd say this is like spot-on fluent wernicke 's aphasia , damage to an area at the junction of two of the brain 's lobes , temporal and parietal , typically on the left side of the brain , is the culprit . this area is physically connected to broca 's area , that you mentioned , by a massive bundle of neurofibers called the arcuate fasciculus . i hypothesize that this massive bundle of connections is completely wiped out in a zombie . it would be like taking out the superhighway between two cities . one city that manufactures a product , and the other that ships it out to the rest of the world . without that highway , the product distribution just shuts down . d1 : so , basically it 's a moot point to reason with a zombie , since they ca n't understand you , let alone talk back . d2 : ( laughs ) i mean , you could try , man , but i 'm going to stay on this side of the glass .
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i 'd say this is like spot-on fluent wernicke 's aphasia , damage to an area at the junction of two of the brain 's lobes , temporal and parietal , typically on the left side of the brain , is the culprit . this area is physically connected to broca 's area , that you mentioned , by a massive bundle of neurofibers called the arcuate fasciculus . i hypothesize that this massive bundle of connections is completely wiped out in a zombie .
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the comprehension and production areas of the language circuit are connected by what bundle of fibers in the brain ?
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[ music ] they 've sat with us at nearly every table , a pair that 's partnered most of the meals ever cooked in western kitchens . a yin and yang , darkness and light . the importance of salt is crystal clear . life would n't exist without it and if it did it would taste gross and weird . but out of all the herbs and spices on the culinary roster how did this ground up gray stuff become the go-to spice of life . seriously , why not salt and turmeric or salt and mustard , salt and cumin , salt and nutmeg , salt and coriander , salt and paprika , salt and cinnamon , salt and allspice , salt and cloves . [ music ] salt , or specifically sodium chloride . it 's the only rock that we eat , the unlikely joining of a poisonous gas and an explosive-metal and when paired with water it provides both the incubator and ingredients for life . we use sodium and chloride ions to keep our cells inflated , to regulate blood pressure and convey electrical nerve impulses throughout our body . to maintain this we need to consume about six grams of sodium chloride every day . so salt 's culinary and cultural value is no surprise its history could fill a book , and it has . a great book by the way . have you guys read the book salt : a world history early hunter-gatherer societies got all the salt needed from their animal diet to this day the masai people of east africa get theirs from drinking the blood of their livestock . but as human society is shifted to growing and eating plants , salt became something you either found or traded for . the earliest sites of salt harvesting date to at least 6,000 bc in china and europe there 's salt in most of the blue wet stuff covering earth once you boil away or evaporate all that pesky h2o but there 's pure sodium chloride in earth 's crust , if you can find it . following animal trails led us to natural salt licks and some of these became our first highways . several ancient salt harvesting cities still bear a pinch of history in their name . entire economies were built around salt . it was a commodity and currency that you could eat . roman warriors deemed worth their salt where sometimes given a salary . the roman custom of salting bitter greens even gave us salad . although that caesar dressing comes from tijuana . today salt is cheap enough to manufacture that many people are in danger of eating too much . but before the industrial age it was scarce enough that people fought wars over it . it even inspired at least one revolution . before refrigeration , salting was one way to keep food from spoiling . since most harmful bacteria ca n't grow in high salt conditions . but obviously salt also changes how we experience our food . it makes things taste salty but it also accentuates other flavors . sodium chloride can chemically block bitter taste receptors and amplify those that sense sweet , salty , and umami . depending on when and how its applied to food it can change the very chemistry of how it 's cooked . salt is probably the most important ingredient on earth . but then there 's pepper . one spice to rule them all . if you thought salt was interesting , pepper is is a thing . black pepper comes from a flowering vine native to southeast asia . it gets its heat from a chemical called piperine . rather than capsaicin like those confusingly named fruits of the chili pepper family . it 's been a common ingredient in indian cooking for at least four thousand years . but small amounts of black pepper made their way to greece , rome , and even ancient egypt , where peppercorns were apparently valuable enough to stuff up the mummified nose of ramses the second . pepper became a key commodity in the spice trade stretching between asia and europe , where its main use like other pungent spices was to mask the flavor of meat that was , shall we say , past its prime . the extreme distances involved in trading pepper across the known world translated into extreme prices . to inflate them further arab traders invented a myth that pepper gardens were guarded by serpents which had to be chased away with fire before a harvest . who would n't want to put magic snake powder on their food . throughout the middle ages it was common to see many spices used in the food of the wealthy , but the enduring popularity of black pepper may owe itself to one picky eater . its said that louis xiv demanded his food lightly seasoned , preferring only salt and pepper be added . the french cuisine developed then was the basis for much of what we eat today , and now pepper is the spice and i 'm sick of it . too long we 've been forced to look at the world of spice in black and white ! held prisoner by pepper , unable to gaze upon the full rainbow of flavors and i say no more ! join me , brothers and sisters , stand together . we say yes to salt . but let us say anything but pepper ! stay spicy , and curious
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pepper became a key commodity in the spice trade stretching between asia and europe , where its main use like other pungent spices was to mask the flavor of meat that was , shall we say , past its prime . the extreme distances involved in trading pepper across the known world translated into extreme prices . to inflate them further arab traders invented a myth that pepper gardens were guarded by serpents which had to be chased away with fire before a harvest . who would n't want to put magic snake powder on their food .
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why did pepper merchants create a myth that pepper gardens were guarded by snakes ?
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( piano playing ) steven : we 're looking at one of the single canvases from a series of canvases of the campbell soup cans by andy warhol from 1962 at the museum of modern art . and one of the really important questions that comes up about , especially modern art , is well , why is this art ? sal : when you ask me that a bunch of things kind of surface in my brain . it does evoke something in me so i 'm inclined to say yes , but then there 's a bunch of other things that say well , if i did n't see this in a museum and if i just saw this in the marketing department of campbell 's soup , would you be viewing it differently ? steven : because it 's advertising then . sal : yes . steven : but in the context of the museum or in the context of andy warhol 's studio , it 's not quite advertising , right ? sal : even if it 's the exact same thing . steven : yeah . sal : and the idea here is by putting it in the museum it 's saying look at this in a different way . steven : well that 's right , it really does relocate it , it does change the meaning , it does transform it , and that 's really one of the central ideas of modern art is that you can take something that 's not necessarily based in technical skill , because i do n't think you would say that this is beautifully rendered . sal : right . steven : but it relocates it and makes us think about it in a different way . sal : and so , i guess he would get credit for taking something that was very , almost mundane , something you see in everyone 's cupboard , and making it a focal point like you should pay attention to this thing . steven : i think that 's exactly right and i think that he 's doing it about a subject that was about as low a subject as one could go . i mean cheap advertising art was something that was so far away from fine art from the great masters and then to focus on something as lowly as a can of soup , and cream of chicken no less , right ? ( laughs ) sal : a lot of it is , if he did it 50 years earlier , people would have thought this guy 's a quack and if he did it now they 'd think he was just derivative and ... it was really just that time where people happened to think this was art . steven : i think that that 's right . in 1962 , what warhol is doing is he 's saying what is it about our culture that is really authentic and important ? and it was about mass production , it was about factories . he in a sense said let 's not be looking at nature as if we were still an agrarian culture , we 're now an industrial culture . what is the stuff of our visual world now ? sal : i think i 'm 80 percent there . i remember in college there was a student run art exhibit and as a prank a student actually put a little podium there and put his lunch tray . he put a little placard next to it , you know , lunch tray on saturday or something is what he called it . so he did it as a prank and everyone thought it was really funny but to some degree it 's kind of a sign that maybe what he did was art . steven : well i think that 's why it was funny because it was so close , right ? sal : and to some degree when someone took a lunch tray and gave it the proper lighting and gave it a podium to look at it and wrote a whole description about it , i did view the lunch tray in a different way . that 's kind of the same idea , that something that 's such a mundane thing but you use it everyday . i mean , what would you say to that ? was that a prank or was that art ? steven : i think it is a prank but it 's also very close to some important art that had been made earlier in the century . he had license to do that because of somebody named marcel duchamp . in fact , warhol had in a sense the same kind of license to not focus on the making of something , not focus on the brushwork , not focus on the composition , not focus on the color , but focus on the refocusing of ideas . sal : and the reason why we talk about warhol or duchamp or any of these people is that , as you said , it 's not that they did something technically profound . obviously campbell soup 's marketing department had already done something as equally as profound , it 's more that they were the people who looked at the world in a slightly different way and highlighted that . steven : well i think that that 's right . warhol is also very consciously working towards asking the same questions that the prankster at your school was asking . he 's saying can this be art ? and in fact he 's really pushing it . look at the painting closely for a moment . this is one of the last paintings that he 's actually painted . he 's really defined the calligraphy of this campbell 's , he 's really sort of rendered the reflection of the tin at the top . but then he stopped and he said , i do n't want to paint the fleur de lis . you see those little fleur de lis down at the bottom . i do n't want to paint those . so he actually had a little rubber stamp made of them and actually sort of placed them down mechanically . what does that mean for an artist then , to say i do n't even want to bother to paint these ? i 'm just going to find a mechanical process to make this easier . warhol is doing something i think which is important which is reflecting the way that we manufacture , the way that we construct our world . think about the things that we surround ourselves with , almost everything was made in a factory . almost nothing is singular in the world anymore . it 's not a world that we would normally find beautiful . sal : i do n't know , sometimes i feel and correct me if i 'm wrong , that a decision was made that warhol was interesting or great and then people will interpret his stuff to justify his greatness . that oh look , he used a printer instead of drawing it which shows that he was reflecting the industrial or whatever , but if he had done it the other way , if he had hand drawn it or hand drawn it with his elbow you know , or finger painted it or something people would say oh is n't this tremendous because we normally would see this thing printed by a machine and now he did it with his hands . how much do you think that is the case or am i just being cynical ? steven : well no , i think that there 's value in a certain degree of cynicism and i think that in some ways what we 're really talking about here is what does it mean to be an avant-garde artist ? what does it mean to sort of change the language of art and to try to find ways that art relates to our historical moment in some really direct and authentic way ? sal : and maybe it 's easy for me to say this because i remember looking at this when i took 5th grade art class , andy warhol and all of that , so now it seems almost not that unique but in '62 what i 'm hearing is that warhol was really noteworthy because he really did push people 's thinking . steven : i think that warhol was looking for , in 1962 , a kind of subject matter that was completely outside of the scope of that we could consider fine art . one of his contemporaries , roy lichtenstein , was asked what pop art was and he said , `` well we were looking for subject matter that was so despicable , `` that was so low , that nobody could possibly believe that it was really art . '' and i think you 're right , i think now we look at it and it 's so much a part of our visual culture that we immediately accept it . but i think that it 's really interesting to retrieve just how shocking and radical that was . sal : this is fascinating . it seems like there 's a lot of potential there , that stuff that 's pseudo-art made for other purposes , for commercial purposes but if you kind of shine a light on it , in the way that a light has been shone on this , that it does ... in your mind would that cross the barrier into being art ? steven : well i think that , you mentioned before , that if somebody was doing this now it would feel really derivative . and i think that that 's right . i think it underscores just how hard it is to find in our culture now , ways of making us see the world in new ways . sal : fascinating . ( piano playing )
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( laughs ) sal : a lot of it is , if he did it 50 years earlier , people would have thought this guy 's a quack and if he did it now they 'd think he was just derivative and ... it was really just that time where people happened to think this was art . steven : i think that that 's right .
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do you think that replicated images of brand-name products ( which you can buy in your grocery store ) can be considered advertising or art ?
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translator : andrea mcdonough reviewer : bedirhan cinar let 's talk about the facts of life . you remember that conversation you had when you were a kid about sex or drugs with your parents or some trusted adult ? probably not because it 's a myth . you do n't talk to kids about that stuff . it 's just so embarrassing . and , hey , maybe that 's ok. we 've been outsourcing the facts of life for decades . we spend billions of dollars on it . so , why talk to kids when you can just turn on the tv ? i learned about drugs from an egg and a frying pan : `` this is drugs , and this is your brain on drugs . pssssssss . any questions ? '' yeah , actually , i did . but it 's not about questions . it 's about data . in the 1980 's when i was growing up , those data were terrifying parents : 1 % of high school seniors had try heroin , 12 % hallucinogens , 12 % tranquilizers , 17 % cocaine , 26 % stimulants , and over 50 % of us had tried marijuana . it was an epidemic ! at least , that 's what they told us . and marijuana was the gateway drug , leading to all the harder stuff . of course , 92 % of us were drinking alcohol , and that was killing more of us than all drugs combined . but , nevermind , it 's legal . so we declared war on drugs ! nancy reagan was our general . all drugs will kill you , so just say , `` no ! '' just say , `` no ! '' to pot . just say , `` no ! '' to cocaine . just say , `` no ! '' to everything . so simple ! if you want to save kids , you have to scare the hell out of them ! and we spent ridiculous amounts of money doing that . soon that war on drugs spread to become a war on sex . we were pushing abstinence on kids to fight aids . and when all the data finally came home , guess what : completely ineffective . we love big solutions to big problems , do n't we ? what if the facts of life do n't work that way ? what if the experience of having that conversation ca n't be mass-produced ? what if it ca n't be scaled up ? well , that would be very frustrating for everyone in this industry , would n't it ? and , many of them are really trying to help . who , then ? us . we have to talk to kids . openly and honestly . but are we ready to be honest ? i do n't think so . we mythologize childhood . mine was in stone mountain , georgia , a completely typical 1980 's american suburb . for the parents , a wholesome paradise of bridge parties and tennis games . for us kids , we were all working on a secret research project , and our laboratory was in the woods after school , under the covers during sleep-overs , really , any opportunity we could take to peel off our clothes and investigate . what were these things , bodies ? what do they do ? we had to figure them out and that 's childhood . it 's not just fun and games , it 's actually a manhattan project of nakedness . and then you walk into your first class in middle school , and the bomb goes off . you are not just a body any more . oh no , now you are grotesque . that 's when the suffering really starts . so , yeah , talk to kids . but if you are not honest about your own experiences first , everything you say smells like bullshit . do n't worry , you can practice and you should start by talking to the one kid you definitely know : you . what kind of kid were you ? what troubled you ? for me , it was age 13 . that was the worst year . i was obsessively curious about sex and also deeply ashamed by it . it was n't my only problem , of course , not by a long shot , but it was the beginning of a downward spiral . and my bad luck was to hit bottom while watching `` the wall '' by pink floyd , which is a bad idea for a miserable 13-year old high on weed . so , that night , for whatever reason , it seemed like good idea to shave off my eyebrows , and then try to kill myself by swallowing all the pills in the bathroom , which was not at all fatal , but everyone noticed the eyebrows . and that made middle school extra fun . so , what was your low point ? and if you could build a time machine to travel back and talk to that kid , what would you say to yourself ? for me , it was easy . all i really needed was someone to reassure me that somehow i was a normal part of the universe . but i did n't feel like i could talk to anyone . and yet weirdly , i fully expected a time traveler to materialize at any time because i was a geek . i did n't know if it would be my unborn son or a t-101 cyborg . but either one would be awesome ! hey , it 's me , yourself from the future , in the year 2012 . i have crucial information for you , but not about the future , about the past , a billion years in the past , when this planet was covered with nothing but cells and all they did was fight , eat , and divide ; fight , eat , and divide . except for one . and that 's your ancestor . this cell enslaved other ones , but master and slave became one . and then those cells invented sex , and then they invented the first bodies with each cell doing a different job , some smelling , some moving , some eating . and the job of sex went to a special cell called the gamete . and those bodies became giant . the distance to the next body was vast so they had to swim . most would be lost and die so they were mass-produced . soon the oceans were a non-stop riot of sex and death until 500 million years ago , when the first beast crawled onto land . land is hard because bodies are heavy . and the sun kills gametes . to keep them safe , so deep inside of a body , the mother builds a tiny ocean . outside are events of unimaginable violence . whole new forms of life are being created only to be wiped away . millions of years are flashing by . but in here , it 's always the same . peace . just peace . maybe we will never know why , but of all the possible bodies that have appeared on this planet , it was this one , bilaterally symmetric , warm-blooded , bigger than a mouse , smaller than a horse , 2 legs , 10 toes , no tail , big brain , language , technology , and civilization rising and falling for thousands of years . and here you are , a 13-year old human perplexed and embarrassed about sex . that 's what i came here to tell you : we do n't know why sex evolved nor why it persists . why do n't we just clone ourselves like all life did a billion years ago ? it 's so much more efficient . we would all have babies , no mates . it could be that children who are genetically different from each other are protected from disease . and that is still our best guess . so be comforted to know that even in the distant future , in the year 2012 , we still do n't know what sex is for . it is perplexing . you should n't be embarrassed by it . sex is a beautiful puzzle . and without it , you simply would not be here . by the way , be nice to your little sister . she 's your best friend . you 'll see .
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all drugs will kill you , so just say , `` no ! '' just say , `` no ! '' to pot .
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bohannon suggests that practicing a conversation with yourself is the best way to know what to say to kids . why does he suggest this method , and do you think it 's good advice ?
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commas are tricky things , especially when subordinates and conjunctions are involved . if you can remember a few basic rules , a simple law of physics , and some common scenarios , you will be able to use commas correctly . i like to think of the different parts of our sentence as characters . let 's meet a few of them : the tiny conjunctions , the mighty subordinates , and the clever comma . conjunctions are small and nimble . they are words that connect clauses , words , and phrases . you can easily remember the conjunctions by remembering the acronym fanboys . the conjunctions are for , and , nor , but , or , yet , so . because they 're so small , more often than not , they require the help of a comma but not always . subordinates , on the other hand , are the wwe heavyweight champions of sentences . they are words that connect two unequal things , dependent and independent clauses . subordinates make it very clear what is being prioritized in a sentence . commonly used subordinates are although , because , before , however , unless , and even though . because subordinates are all about power , they can do a lot of heavy lifting by themselves . but , of course , sometimes even the strongest among us needs some help from our clever friends . because our clever comma is so nice , she often roams her neighborhood looking for some community service to do . today , as soon as she leaves her house , she sees a subordinate lifting the weight of two complete sentences , one on each arm . bartheleme loves engaging in political debate even though he usually loses . the comma asks the subordinate if he needs help . well , we know that subordinates are the wwe heavyweight champions of sentences . they can easily hold the weight of these two complete sentences because they are distributed evenly on both arms . so , when the comma asks if it can help , the subordinate is appalled at the idea of needing assistance . no thanks , maybe next time ! so , the comma continues on . soon , she seems a couple of subordinates attempting to lift the weight of sentences directly in front of themselves . even though bartheleme loves to sing , he never sings in front of others . the comma asks the subordinates if they need help . they might not want to admit it , but this time the subordinates do need help . complete sentences weigh quite a bit . simple physics tells us that it 's easier to balance heavy objects if the weight is evenly distributed . so , while the subordinates are quite capable of balancing two complete sentences when carrying the weight on both sides , they 're having trouble picking just one up . the comma rushes over to help the struggling subordinates , but how will she help ? when subordinates begin sentences , the comma will place herself directly after the first thought or complete sentence . after helping the subordinates , our comma heroine continues on and spots a conjunction holding the weight of two complete sentences . bartheleme was accepted into the university of chicago , and he is on the waitlist for stanford university . the comma asks the conjunction if he needs help . of course he does ! hurry ! the comma rushes and places itself before the conjunction . fanboys are n't as militant as subordinates . for this reason , the commas do n't have to fall in line behind the fanboys . fanboys are courteous creatures . they allow the comma to go ahead of them . helping others is hard work ! on her way home , our comma sees a conjunction holding up the weight of a complete sentence and a fragment sentence . bartheleme is going to major in molecular biology or interpretive dance . the now-exhausted comma asks the conjunction if he needs help lifting the items . this is one of the rare occassions where a conjunction does n't need the help of a comma . the conjunction assures the comma that help is n't needed , which is good for the comma because by now , all it wants to do is go home and rest up for another day of vigilant sentence constructing .
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on her way home , our comma sees a conjunction holding up the weight of a complete sentence and a fragment sentence . bartheleme is going to major in molecular biology or interpretive dance . the now-exhausted comma asks the conjunction if he needs help lifting the items .
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harold is an excellent singer and he can dance all of the latest dance moves .
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now , my subject is success , so people sometimes call me a `` motivational speaker . '' but i want you to know right up front i 'm not a motivational speaker . i could n't pass the height requirement . ( laughter ) and i could n't motivate anybody . my employees actually call me a de-motivational speaker . ( laughter ) what i try to be is an informational speaker . i went out and found out some information about success , and i 'm just here to pass it on . and my story started over ten years ago , on a plane . i was on my way to the ted conference in california , and in the seat next to me was a teenage girl , and she came from a really poor family , but she wanted to get somewhere in life . and as i tapped away on my computer , she kept asking me questions , and then out of the blue , she asked , `` are you successful ? '' i said , `` no , i 'm not successful . '' terry fox , my hero , now there 's a big success . he lost a leg to cancer , then ran thousands of miles and raised millions for cancer research . or bill gates , a guy who owns his own plane and does n't have to sit next to some kid asking him questions . ( laughter ) but then i told her about some of the stuff i 'd done . i love communications , and i 've won lots of awards in marketing . i love running , and i still sometimes win my age group , old farts over 60 . ( laughter ) my fastest marathon is two hours and 43 minutes to run the 26 miles , or 42 kilometers . i 've run over 50 marathons , in all 7 continents . this was a run my wife and i did up the inca trail to machu picchu in peru . and to qualify for the 7 continents , we had to run a marathon in antarctica . but when we got there , it did n't look nice and calm like this , it looked like this . the waves were so high , we could n't get to shore . so we sailed 200 miles further south to where the seas were calm and ran the entire 26-mile marathon on the boat . 422 laps around the deck of that little boat . my wife and i have also climbed two of the world 's seven summits , the highest mountains on each continent . we climbed aconcagua , the highest mountain on the american continent , and kilimanjaro , the highest mountain in africa . well , to be honest , i puked my way to the top of kilimanjaro , i got altitude sickness . i got no sympathy from my wife . she passed me and did a lap around the top while i was still struggling up there . in spite of that , we 're still together and have been for over 35 years . ( applause ) i 'd say that 's a success these days . so i said to the girl , `` well , you know , i guess i have had some success . '' and then she said , `` okay , so are you a millionaire ? '' ( laughter ) now , i did n't know what to say , because when i grew up , it was bad manners to talk about money . but i figured i 'd better be honest , and i said , `` yeah . i 'm a millionaire . but i do n't know how it happened . i never went after the money , and it 's not that important to me . '' she said , `` maybe not to you , but it is to me . i do n't want to be poor all my life . i want to get somewhere , but it 's never going to happen . '' i said , `` well , why not ? '' she said , `` well , you know , i 'm not very smart . i 'm not doing great in school . '' i said , `` so what ? i 'm not smart . i barely passed high school . i had absolutely nothing going for me . i was never voted most popular or most likely to succeed . i started a whole new category -- most likely to fail . but in the end , i did okay . so if i can do it , you can do it . '' and then she asked me the big question : `` okay , so what really leads to success ? '' i said , `` jeez , sorry . i do n't know . i guess somehow i did it . i do n't know how i did it . '' so i get off the plane and go to the ted conference , and i 'm standing in a room full of extraordinarily successful people in many fields -- business , science , arts , health , technology , the environment -- when it hit me : why do n't i ask them what helped them succeed , and find out what really leads to success for everyone ? so i was all excited to get out there and start talking to these great people , when the self-doubt set in . i mean , why would people want to talk to me ? i 'm not a famous journalist . i 'm not even a journalist . so i was ready to stop the project before it even began , when who comes walking towards me but ben cohen , the famous co-founder of ben and jerry 's ice cream . i figured it was now or never . i pushed through the self-doubt , jumped out in front of him , and said , `` ben , i 'm working on this project . i do n't even know what to ask you , but can you tell me what helped you succeed ? '' he said , `` yeah , sure , come on . let 's go for a coffee . '' and over coffee and ice cream , ben told me his story . now here we are over 10 years later , and i 've interviewed over 500 successful people face-to-face , and collected thousands of other success stories . i wanted to find the common factors for success in all fields , so i had to interview people in careers ranging from a to z . these are just the careers i interviewed beginning with the letter a , and in most cases more than one person . i interviewed six successful accountants , five corporate auditors , five astronauts who had been into space , four actors who had won the academy award for best actor , three of the world 's top astrophysicists , six of the world 's leading architects and , oh yeah , four nobel prize winners . yeah , i know it does n't start with a , but it 's kind of cool . ( laughter ) and i want to say a sincere thanks to all the great people that i 've interviewed over the years . this really is their story ; i 'm just the messenger . the really big job was taking all the interviews and analyzing them , word by word , line by line , and sorting them into all the factors that people said helped them succeed . and then you start to see the big factors that are common to most people 's success . altogether , i analyzed and sorted millions of words . do you know how much work that is ? that 's all i do , day and night -- sort and analyze . i 'll tell you , if i ever get my hands on that kid on the plane -- ( laughter ) actually , if i do , i 'll thank her . because i 've never had so much fun and met so many interesting people . and now , i can answer her question . i discovered the 8 traits successful people have in common , or the 8 to be great : love what you do ; work really hard ; focus on one thing , not everything ; keep pushing yourself ; come up with good ideas ; keep improving yourself and what you do ; serve others something of value , because success is n't just about me , me , me ; and persist , because there 's no overnight success . why did i pick these ? because when i added up all the comments in my interviews , more people said those 8 things helped them than anything else . the eight traits are really the heart of success , the foundation , and then on top we build the specific skills that we need for our particular field or career . technical skills , analytical skills , people skills , creative skills -- lots of other skills we can add on top , depending on our field . but no matter what field we 're in , these eight traits will be at the heart of our success . ( applause )
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i wanted to find the common factors for success in all fields , so i had to interview people in careers ranging from a to z . these are just the careers i interviewed beginning with the letter a , and in most cases more than one person . i interviewed six successful accountants , five corporate auditors , five astronauts who had been into space , four actors who had won the academy award for best actor , three of the world 's top astrophysicists , six of the world 's leading architects and , oh yeah , four nobel prize winners .
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meeting one person can change your life . here are some people i ’ ve met . which one asked me the question that changed my life ?
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translator : andrea mcdonough reviewer : jessica ruby big data is an elusive concept . it represents an amount of digital information , which is uncomfortable to store , transport , or analyze . big data is so voluminous that it overwhelms the technologies of the day and challenges us to create the next generation of data storage tools and techniques . so , big data is n't new . in fact , physicists at cern have been rangling with the challenge of their ever-expanding big data for decades . fifty years ago , cern 's data could be stored in a single computer . ok , so it was n't your usual computer , this was a mainframe computer that filled an entire building . to analyze the data , physicists from around the world traveled to cern to connect to the enormous machine . in the 1970 's , our ever-growing big data was distributed across different sets of computers , which mushroomed at cern . each set was joined together in dedicated , homegrown networks . but physicists collaborated without regard for the boundaries between sets , hence needed to access data on all of these . so , we bridged the independent networks together in our own cernet . in the 1980 's , islands of similar networks speaking different dialects sprung up all over europe and the states , making remote access possible but torturous . to make it easy for our physicists across the world to access the ever-expanding big data stored at cern without traveling , the networks needed to be talking with the same language . we adopted the fledgling internet working standard from the states , followed by the rest of europe , and we established the principal link at cern between europe and the states in 1989 , and the truly global internet took off ! physicists could easily then access the terabytes of big data remotely from around the world , generate results , and write papers in their home institutes . then , they wanted to share their findings with all their colleagues . to make this information sharing easy , we created the web in the early 1990 's . physicists no longer needed to know where the information was stored in order to find it and access it on the web , an idea which caught on across the world and has transformed the way we communicate in our daily lives . during the early 2000 's , the continued growth of our big data outstripped our capability to analyze it at cern , despite having buildings full of computers . we had to start distributing the petabytes of data to our collaborating partners in order to employ local computing and storage at hundreds of different institutes . in order to orchestrate these interconnected resources with their diverse technologies , we developed a computing grid , enabling the seamless sharing of computing resources around the globe . this relies on trust relationships and mutual exchange . but this grid model could not be transferred out of our community so easily , where not everyone has resources to share nor could companies be expected to have the same level of trust . instead , an alternative , more business-like approach for accessing on-demand resources has been flourishing recently , called cloud computing , which other communities are now exploiting to analyzing their big data . it might seem paradoxical for a place like cern , a lab focused on the study of the unimaginably small building blocks of matter , to be the source of something as big as big data . but the way we study the fundamental particles , as well as the forces by which they interact , involves creating them fleetingly , colliding protons in our accelerators and capturing a trace of them as they zoom off near light speed . to see those traces , our detector , with 150 million sensors , acts like a really massive 3-d camera , taking a picture of each collision event - that 's up to 14 millions times per second . that makes a lot of data . but if big data has been around for so long , why do we suddenly keep hearing about it now ? well , as the old metaphor explains , the whole is greater than the sum of its parts , and this is no longer just science that is exploiting this . the fact that we can derive more knowledge by joining related information together and spotting correlations can inform and enrich numerous aspects of everyday life , either in real time , such as traffic or financial conditions , in short-term evolutions , such as medical or meteorological , or in predictive situations , such as business , crime , or disease trends . virtually every field is turning to gathering big data , with mobile sensor networks spanning the globe , cameras on the ground and in the air , archives storing information published on the web , and loggers capturing the activities of internet citizens the world over . the challenge is on to invent new tools and techniques to mine these vast stores , to inform decision making , to improve medical diagnosis , and otherwise to answer needs and desires of tomorrow 's society in ways that are unimagined today .
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to see those traces , our detector , with 150 million sensors , acts like a really massive 3-d camera , taking a picture of each collision event - that 's up to 14 millions times per second . that makes a lot of data . but if big data has been around for so long , why do we suddenly keep hearing about it now ?
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what is referred to as data mining ?
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we live in an age of protest . on campuses and public squares , on streets and social media , protesters around the world are challenging the status quo . protest can thrust issues onto the national or global agenda , it can force out tyrants , it can activate people who have long been on the sidelines of civic life . while protest is often necessary , is it sufficient ? consider the arab spring . all across the middle east , citizen protesters were able to topple dictators . afterwards , though , the vacuum was too often filled by the most militant and violent . protest can generate lasting positive change when it 's followed by an equally passionate effort to mobilize voters , to cast ballots , to understand government , and to make it more inclusive . so here are three core strategies for peacefully turning awareness into action and protest into durable political power . first , expand the frame of the possible , second , choose a defining fight , and third , find an early win . let 's start with expanding the frame of the possible . how often have you heard in response to a policy idea , `` that 's just never going to happen '' ? when you hear someone say that , they 're trying to define the boundaries of your civic imagination . the powerful citizen works to push those boundaries outward , to ask what if - what if it were possible ? what if enough forms of power - people power , ideas , money , social norms - were aligned to make it happen ? simply asking that question and not taken as given all the givens of conventional politics is the first step in converting protest to power . but this requires concreteness about what it would look like to have , say , a radically smaller national government , or , by contrast , a big single-payer healthcare system , a way to hold corporations accountable for their misdeeds , or , instead , a way to free them from onerous regulations . this brings us to the second strategy , choosing a defining fight . all politics is about contrasts . few of us think about civic life in the abstract . we think about things in relief compared to something else . powerful citizens set the terms of that contrast . this does n't mean being uncivil . it simply means thinking about a debate you want to have on your terms over an issue that captures the essence of the change you want . this is what the activists pushing for a $ 15 minimum wage in the u.s. have done . they do n't pretend that $ 15 by itself can fix inequality , but with this ambitious and contentious goal , which they achieved first in seattle and then beyond , they have forced a bigger debate about economic justice and prosperity . they 've expanded the frame of the possible , strategy one , and created a sharp emblematic contrast , strategy two . the third key strategy , then , is to seek and achieve an early win . an early win , even if it 's not as ambitious as the ultimate goal , creates momentum , which changes what people think is possible . the solidarity movement , which organized workers in cold war poland emerged just this way , first , with local shipyard strikes in 1980 that forced concessions , then , over the next decade , a nationwide effort that ultimately helped topple poland 's communist government . getting early wins sets in motion a positive feedback loop , a contagion , a belief , a motivation . it requires pressuring policymakers , using the media to change narrative , making arguments in public , persuading skeptical neighbors one by one by one . none of this is as sexy as a protest , but this is the history of the u.s. civil rights movement , of indian independence , of czech self-determination . not the single sudden triumph , but the long , slow slog . you do n't have to be anyone special to be part of this grind , to expand the frame of the possible , to pick a defining fight , or to secure an early win . you just have to be a participant and to live like a citizen . the spirit of protest is powerful . so is showing up after the protest . you can be the co-creator of what comes next .
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the solidarity movement , which organized workers in cold war poland emerged just this way , first , with local shipyard strikes in 1980 that forced concessions , then , over the next decade , a nationwide effort that ultimately helped topple poland 's communist government . getting early wins sets in motion a positive feedback loop , a contagion , a belief , a motivation . it requires pressuring policymakers , using the media to change narrative , making arguments in public , persuading skeptical neighbors one by one by one .
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explain the importance of an “ early win ” to a movement and how it contributes to a positive feedback loop .
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when it was ratified in 1789 , the u.s. constitution did n't just institute a government by the people . it provided a way for the people to alter the constitution itself . and yet , of the nearly 11,000 amendments proposed in the centuries since , only 27 have succeeded as of 2016 . so what is it that makes the constitution so hard to change ? in short , its creators . the founders of the united states were trying to create a unified country from thirteen different colonies , which needed assurance that their agreements could n't be easily undone . so here 's what they decided . for an amendment to even be proposed , it must receive a two-thirds vote of approval in both houses of congress , or a request from two-thirds of state legislatures to call a national convention , and that 's just the first step . to actually change the constitution , the amendment must be ratified by three-quarters of all states . to do this , each state can either have its legislature vote on the amendment , or it can hold a separate ratification convention with delegates elected by voters . the result of such high thresholds is that , today , the american constitution is quite static . most other democracies pass amendments every couple of years . the u.s. , on the other hand , has n't passed one since 1992 . at this point , you may wonder how any amendments managed to pass at all . the first ten , known as the bill of rights , includes some of america 's most well-known freedoms , such as the freedom of speech , and the right to a fair trial . these were passed all at once to resolve some conflicts from the original constitutional convention . years later , the thirteenth amendment , which abolished slavery , as well as the fourteenth and fifteenth amendments , only passed after a bloody civil war . ratifying amendments has also become harder as the country has grown larger and more diverse . the first ever proposed amendment , a formula to assign congressional representatives , was on the verge of ratification in the 1790s . however , as more and more states joined the union , the number needed to reach the three-quarter mark increased as well , leaving it unratified to this day . today , there are many suggested amendments , including outlawing the burning of the flag , limiting congressional terms , or even repealing the second amendment . while many enjoy strong support , their likelihood of passing is slim . americans today are the most politically polarized since the civil war , making it nearly impossible to reach a broad consensus . in fact , the late supreme court justice antonin scalia once calculated that due to america 's representative system of government , it could take as little as 2 % of the total population to block an amendment . of course , the simplest solution would be to make the constitution easier to amend by lowering the thresholds required for proposal and ratification . that , however , would require its own amendment . instead , historical progress has mainly come from the u.s. supreme court , which has expanded its interpretation of existing constitutional laws to keep up with the times . considering that supreme court justices are unelected and serve for life once appointed , this is far from the most democratic option . interestingly , the founders themselves may have foreseen this problem early on . in a letter to james madison , thomas jefferson wrote that laws should expire every 19 years rather than having to be changed or repealed since every political process is full of obstacles that distort the will of the people . although he believed that the basic principles of the constitution would endure , he stressed that the earth belongs to the living , and not to the dead .
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instead , historical progress has mainly come from the u.s. supreme court , which has expanded its interpretation of existing constitutional laws to keep up with the times . considering that supreme court justices are unelected and serve for life once appointed , this is far from the most democratic option . interestingly , the founders themselves may have foreseen this problem early on .
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if you had a choice , who should have the power to amend the us constitution - just over 50 % of the american people , or five out of nine us supreme court justices ? explain .
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they 're everywhere , but you will never see one . trillions of them are flying through you right this second , but you ca n't feel them . these ghost particles are called neutrinos and if we can catch them , they can tell us about the furthest reaches and most extreme environments of the universe . neutrinos are elementary particles , meaning that they ca n't be subdivided into other particles the way atoms can . elementary particles are the smallest known building blocks of everything in the universe , and the neutrino is one of the smallest of the small . a million times less massive than an electron , neutrinos fly easily through matter , unaffected by magnetic fields . in fact , they hardly ever interact with anything . that means that they can travel through the universe in a straight line for millions , or even billions , of years , safely carrying information about where they came from . so where do they come from ? pretty much everywhere . they 're produced in your body from the radioactive decay of potassium . cosmic rays hitting atoms in the earth 's atmosphere create showers of them . they 're produced by nuclear reactions inside the sun and by radioactive decay inside the earth . and we can generate them in nuclear reactors and particle accelerators . but the highest energy neutrinos are born far out in space in environments that we know very little about . something out there , maybe supermassive black holes , or maybe some cosmic dynamo we 've yet to discover , accelerates cosmic rays to energies over a million times greater than anything human-built accelerators have achieved . these cosmic rays , most of which are protons , interact violently with the matter and radiation around them , producing high-energy neutrinos , which propagate out like cosmic breadcrumbs that can tell us about the locations and interiors of the universe 's most powerful cosmic engines . that is , if we can catch them . neutrinos ' limited interactions with other matter might make them great messengers , but it also makes them extremely hard to detect . one way to do so is to put a huge volume of pure transparent material in their path and wait for a neutrino to reveal itself by colliding with the nucleus of an atom . that 's what 's happening in antarctica at icecube , the world 's largest neutrino telescope . it 's set up within a cubic kilometer of ice that has been purified by the pressure of thousands of years of accumulated ice and snow , to the point where it 's one of the clearest solids on earth . and even though it 's shot through with boreholes holding over 5,000 detectors , most of the cosmic neutrinos racing through icecube will never leave a trace . but about ten times a year , a single high-energy neutrino collides with a molecule of ice , shooting off sparks of charged subatomic particles that travel faster through the ice than light does . in a similar way to how a jet that exceeds the speed of sound produces a sonic boom , these superluminal charged particles leave behind a cone of blue light , kind of a photonic boom . this light spreads through icecube , hitting some of its detectors located over a mile beneath the surface . photomultiplier tubes amplify the signal , which contains information about the charged particles ' paths and energies . the data are beamed to astrophysicists around the world who look at the patterns of light for clues about the neutrinos that produced them . these super energetic collisions are so rare that icecube 's scientists give each neutrino nicknames , like big bird and dr. strangepork . icecube has already observed the highest energy cosmic neutrinos ever seen . the neutrinos it detects should finally tell us where cosmic rays come from and how they reached such extreme energies . light , from infrared , to x-rays , to gamma rays , has given us increasingly energetic and continuously surprising views of the universe . we are now at the dawn of the age of neutrino astronomy , and we have no idea what revelations icecube and other neutrino telescopes may bring us about the universe 's most violent , most energetic phenomena .
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in a similar way to how a jet that exceeds the speed of sound produces a sonic boom , these superluminal charged particles leave behind a cone of blue light , kind of a photonic boom . this light spreads through icecube , hitting some of its detectors located over a mile beneath the surface . photomultiplier tubes amplify the signal , which contains information about the charged particles ' paths and energies .
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how many individual sensors or detectors does icecube have ?
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where does all this stuff come from ? this rock ? that cow ? your heart ? not the things themselves , mind you , but what they 're made of : the atoms that are the fabric of all things . to answer that question , we look to the law of conservation of mass . this law says take an isolated system defined by a boundary that matter and energy can not cross . inside this system , mass , a.k.a . matter and energy , can neither be created nor destroyed . the universe , to the best of our knowledge , is an isolated system . but before we get to that , let 's look at a much smaller and simpler one . here we have six carbon atoms , 12 hydrogen atoms , and 18 oxygen atoms . with a little energy , our molecules can really get moving . these atoms can bond together to form familiar molecules . here 's water , and here 's carbon dioxide . we ca n't create or destroy mass . we 're stuck with what we 've got , so what can we do ? ah , they have a mind of their own . let 's see . they 've formed more carbon dioxide and water , six of each . add a little energy , and we can get them to reshuffle themselves to a simple sugar , and some oxygen gas . our atoms are all accounted for : 6 carbon , 12 hydrogen , and 18 oxygen . the energy we applied is now stored in the bonds between atoms . we can rerelease that energy by breaking that sugar back into water and carbon dioxide , and still , same atoms . let 's put a few of our atoms aside and try something a little more explosive . this here is methane , most commonly associated with cow flatulence , but also used for rocket fuel . if we add some oxygen and a little bit of energy , like you might get from a lit match , it combusts into carbon dioxide , water and even more energy . notice our methane started with four hydrogen , and at the end we still have four hydrogen captured in two water molecules . for a grand finale , here 's propane , another combustible gas . we add oxygen , light it up , and boom . more water and carbon dioxide . this time we get three co2s because the propane molecule started with three carbon atoms , and they have nowhere else to go . there are many other reactions we can model with this small set of atoms , and the law of conservation of mass always holds true . whatever matter and energy go into a chemical reaction are present and accounted for when it 's complete . so if mass ca n't be created or destroyed , where did these atoms come from in the first place ? let 's turn back the clock and see . further , further , further , too far . okay , there it is . the big bang . our hydrogen formed from a high-energy soup of particles in the three minutes that followed the birth of our universe . eventually , clusters of atoms accumulated and formed stars . within these stars , nuclear reactions fused light elements , such as hydrogen and helium , to form heavier elements , such as carbon and oxygen . at first glance , these reactions may look like they 're breaking the law because they release an astounding amount of energy , seemingly out of nowhere . however , thanks to einstein 's famous equation , we know that energy is equivalent to mass . it turns out that the total mass of the starting atoms is very slightly more than the mass of the products , and that loss of mass perfectly corresponds to the gain in energy , which radiates out from the star as light , heat and energetic particles . eventually , this star went supernova and scattered its elements across space . long story short , they found each other and atoms from other supernovas , formed the earth , and 4.6 billion years later got scooped up to play their parts in our little isolated system . but they 're not nearly as interesting as the atoms that came together to form you , or that cow , or this rock . and that is why , as carl sagan famously told us , we are all made of star stuff .
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our hydrogen formed from a high-energy soup of particles in the three minutes that followed the birth of our universe . eventually , clusters of atoms accumulated and formed stars . within these stars , nuclear reactions fused light elements , such as hydrogen and helium , to form heavier elements , such as carbon and oxygen .
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what process in stars played a role in the formation of the universe ?
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in 1962 , a cave explorer named michel siffre started a series of experiments where he isolated himself underground for months without light or clocks . he attached himself to electrodes that monitored his vital signs and kept track of when he slept and ate . when siffre finally emerged , the results of his pioneering experiments revealed that his body had kept to a regular sleeping-waking cycle . despite having no external cues , he fell asleep , woke up , and ate at fixed intervals . this became known as a circadian rhythm from the latin for `` about a day . '' scientists later found these rhythms affect our hormone secretion , how our bodies process food , and even the effects of drugs on our bodies . the field of sciences studying these changes is called chronobiology . being able to sense time helps us do everything from waking and sleeping to knowing precisely when to catch a ball that 's hurtling towards us . we owe all these abilities to an interconnected system of timekeepers in our brains . it contains the equivalent of a stopwatch telling us how many seconds elapsed , a clock counting the hours of the day , and a calendar notifying us of the seasons . each one is located in a different brain region . siffre , stuck in his dark cave , relied on the most primitive clock in the suprachiasmatic nucleus , or scn of the hypothalamus . here 's the basics of how we think it works based on fruitfly and mouse studies . proteins known as clk , or clock , accumulate in the scn throughout the day . in addition to activating genes that tell us to stay awake , they make another protein called per . when enough per accumulates , it deactivates the gene that makes clk , eventually making us fall asleep . then , clock falls low , so per concentrations also drop again , allowing clk to rise , starting the cycle over . there are other proteins involved , but our day and night cycle may be driven in part by this seesaw effect between clk by day and per by night . for more precision , our scns also rely on external cues like light , food , noise , and temperature . we called these zeitgebers , german for `` givers of time . '' siffre lacked many of these cues underground , but in normal life , they fine tune our daily behavior . for instance , as natural morning light filters into our eyes , it helps wake us up . traveling through the optic nerve to the scn , it communicates what 's happening in the outside world . the hypothalamus then halts the production of melatonin , a hormone that triggers sleep . at the same time , it increases the production of vasopressin and noradrenaline throughout the brain , which help control our sleep cycles . at about 10 am , the body 's rising temperature drives up our energy and alertness , and later in the afternoon , it also improves our muscle activity and coordination . bright screens at night can confuse these signals , which is why binging on tv before bed makes it harder to sleep . but sometimes we need to be even more precise when telling the time , which is where the brain 's internal stopwatch chimes in . one theory for how this works involves the fact that communication between a given pair of neurons always takes roughly the same amount of time . so neurons in our cortex and other brain areas may communicate in scheduled , predictable loops that the cortex uses to judge with precision how much time has passed . that creates our perception of time . in his cave , siffre made a fascinating additional discovery about this . every day , he challenged himself to count up to 120 at the rate of one digit per second . over time , instead of taking two minutes , it began taking him as long as five . life in the lonely , dark cave had warped siffre 's own perception of time despite his brain 's best efforts to keep him on track . this makes us wonder what else influences our sense of time . and if time is n't objective , what does that mean ? could each of us be experiencing it differently ? only time will tell .
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despite having no external cues , he fell asleep , woke up , and ate at fixed intervals . this became known as a circadian rhythm from the latin for `` about a day . '' scientists later found these rhythms affect our hormone secretion , how our bodies process food , and even the effects of drugs on our bodies .
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which are the main proteins in the circadian rhythm ?
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if you visit a museum with a collection of modern and contemporary art , you 're likely to see works that sometimes elicit the response , `` my cat could make that , so how is it art ? '' a movement called abstract expressionism , also known as the new york school , gets this reaction particularly often . abstract expressionism started in 1943 and developed after the end of world war ii . it 's characterized by large , primarily abstract paintings , all-over compositions without clear focal points , and sweeping swaths of paint embodying and eliciting emotions . the group of artists who are considered abstract expressionists includes barnett newman with his existential zips , willem de kooning , famous for his travestied women , helen frankenthaler , who created soak-stains , and others . but perhaps the most famous , influential , and head-scratching one was jackson pollock . most of his paintings are immediately recognizable . they feature tangled messes of lines of paint bouncing around in every direction on the canvas . and sure , these fields of chaos are big and impressive , but what 's so great about them ? did n't he just drip the paint at random ? ca n't anyone do that ? well , the answer to these questions is both yes and no . while pollock implemented a technique anyone is technically capable of regardless of artistic training , only he could have made his paintings . this paradox relates to his work 's roots in the surrealist automatic drawings of andré masson and others . these surrealists supposedly drew directly from the unconscious to reveal truths hidden within their minds . occasionally , instead of picturing something and then drawing it , they let their hands move automatically and would later tease out familiar figures that appeared in the scribbles . and after pollock moved away from representation , he made drip , or action , paintings following a similar premise , though he developed a signature technique and never looked for images or messages hidden in the works . first , he took the canvas off of the easel and laid it on the floor , a subversive act in itself . then , in a controlled dance , he stepped all around the canvas , dripping industrial paint onto it from stirrers and other tools , changing speed and direction to control how the paint made contact with the surface . these movements , like the surrealist scribbles , were supposedly born out of pollock 's subconscious . but unlike the surrealists , whose pictures represented the mind 's hidden contents , pollock 's supposedly made physical manifestations of his psyche . his paintings are themselves signatures of his mind . in theory , anyone could make a painting that is an imprint of their mind . so why is pollock so special ? well , it 's important to remember that while anyone could have done what he did , he and the rest of the new york school were the ones who actually did it . they destroyed conventions of painting that had stood for centuries , forcing the art world to rethink them entirely . but one last reason why jackson pollock 's work has stayed prominent stems from the specific objects he made , which embody fascinating contradictions . for instance , while pollock 's process resulted in radically flat painted surfaces , the web of painted lines can create the illusion of an infinite layered depth when examined up close . and the chaos of this tangled mess seems to defy all control , but it 's actually the product of a deliberate , though not pre-planned , process . these characteristics made pollock into a celebrity , and within art history , they also elevated him to the mythified status of the genius artist as hero . so rather than evening the playing field for all creative minds , his work unfortunately reinforced a long-standing elitist aspect of art . elitist , innovative , whatever you choose to call it , the history embedded in abstract expressionism is one that no cat , however talented , can claim .
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his paintings are themselves signatures of his mind . in theory , anyone could make a painting that is an imprint of their mind . so why is pollock so special ? well , it 's important to remember that while anyone could have done what he did , he and the rest of the new york school were the ones who actually did it .
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what innovations did pollock bring to painting ?
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wars are a tragic part of our history and will almost certainly be a tragic part of our future . since the establishment of the united nations , wars of aggression have been outlawed and multilateral conventions refer to armed conflict instead of war . but the wars of the future wo n't be like the wars of our past . alongside traditional warfare , our future will include cyberwarfare , remotely fighting our enemies through the use of a new class of weapons , including computer viruses and programs to alter the enemy 's ability to operate . and not only is cyberwarfare not covered by existing legal frameworks , but the question of what exactly constitutes cyberwarfare is still highly debated . so , how can we deal with cyberwarfare if we ca n't even agree on what it means ? one way forward is to envision situations where new international laws may be needed . imagine a new kind of assassin , one that could perpetrate a crime without firing a single shot or even being in the same country . for example , an individual working for the government uses a wireless device to send a signal to another foreign leader 's pacemaker . this device directs the pacemaker to malfunction , ultimately resulting in the foreign leader 's death . would this cyber assassination constitute an act of war ? as a second example , imagine an allied group of nations cooperatively infiltrating the computer systems of an enemy nation 's nuclear warship . this attack results in a nuclear-powered aircraft carrier almost melting down , which was stopped just short of killing thousands of soldiers and civilians . as a defensive measure , the enemy country responds by unleashing a defensive cyberattack that results in the allied nations ' power grids going down . hospitals can no longer treat patients , entire regions without heat or clean water , all ultimately causing tens of thousands civilian deaths . the origin of the power failure was the counterattack , but the fragile infrastructure , feeble cybersecurity , and the antiquated state of the power grid all contributed to the deaths of the civilians . could the country fight back ? who would they fight ? and would their retaliation be considered an act of war ? do they constitute war crimes against humanity ? who is to be held responsible ? the computer programmers who wrote the code ? the military project manager who oversaw the creation of the code ? the commander who hit the button , setting off the event ? the hardware engineer who created the computers , knowing that they were intended to enable an attack ? because war has been with us for so long , we have laws to deal with figuring out who should be held accountable for their actions in combat . these legal frameworks aim to contain and prevent atrocities from being more atrocious . commandeering civilian planes and using them as weapons , dropping atomic bombs , the use of gas chambers or poisonous gas in conflict , all of these actions , if committed , constitute acts of war and war crimes under customary international law and the hague conventions . again , the current legal framework stays silent on hypothetical questions and countless others because there are no easy answers , and there are only two ways to make progress on these questions : peace or new laws . so , what hypothetical but plausible scenarios can you imagine falling under the burgeoning definition of cyberwarfare , and how might you design an international legal framework to deter these activities ?
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this device directs the pacemaker to malfunction , ultimately resulting in the foreign leader 's death . would this cyber assassination constitute an act of war ? as a second example , imagine an allied group of nations cooperatively infiltrating the computer systems of an enemy nation 's nuclear warship .
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a cyber attack by a sovereign nation that takes down a city power grid constitutes an act of war .
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the heisenberg uncertainty principle is one of a handful of ideas from quantum physics to expand into general pop culture . it says that you can never simultaneously know the exact position and the exact speed of an object and shows up as a metaphor in everything from literary criticism to sports commentary . uncertainty is often explained as a result of measurement , that the act of measuring an object 's position changes its speed , or vice versa . the real origin is much deeper and more amazing . the uncertainty principle exists because everything in the universe behaves like both a particle and a wave at the same time . in quantum mechanics , the exact position and exact speed of an object have no meaning . to understand this , we need to think about what it means to behave like a particle or a wave . particles , by definition , exist in a single place at any instant in time . we can represent this by a graph showing the probability of finding the object at a particular place , which looks like a spike , 100 % at one specific position , and zero everywhere else . waves , on the other hand , are disturbances spread out in space , like ripples covering the surface of a pond . we can clearly identify features of the wave pattern as a whole , most importantly , its wavelength , which is the distance between two neighboring peaks , or two neighboring valleys . but we ca n't assign it a single position . it has a good probability of being in lots of different places . wavelength is essential for quantum physics because an object 's wavelength is related to its momentum , mass times velocity . a fast-moving object has lots of momentum , which corresponds to a very short wavelength . a heavy object has lots of momentum even if it 's not moving very fast , which again means a very short wavelength . this is why we do n't notice the wave nature of everyday objects . if you toss a baseball up in the air , its wavelength is a billionth of a trillionth of a trillionth of a meter , far too tiny to ever detect . small things , like atoms or electrons though , can have wavelengths big enough to measure in physics experiments . so , if we have a pure wave , we can measure its wavelength , and thus its momentum , but it has no position . we can know a particles position very well , but it does n't have a wavelength , so we do n't know its momentum . to get a particle with both position and momentum , we need to mix the two pictures to make a graph that has waves , but only in a small area . how can we do this ? by combining waves with different wavelengths , which means giving our quantum object some possibility of having different momenta . when we add two waves , we find that there are places where the peaks line up , making a bigger wave , and other places where the peaks of one fill in the valleys of the other . the result has regions where we see waves separated by regions of nothing at all . if we add a third wave , the regions where the waves cancel out get bigger , a fourth and they get bigger still , with the wavier regions becoming narrower . if we keep adding waves , we can make a wave packet with a clear wavelength in one small region . that 's a quantum object with both wave and particle nature , but to accomplish this , we had to lose certainty about both position and momentum . the positions is n't restricted to a single point . there 's a good probability of finding it within some range of the center of the wave packet , and we made the wave packet by adding lots of waves , which means there 's some probability of finding it with the momentum corresponding to any one of those . both position and momentum are now uncertain , and the uncertainties are connected . if you want to reduce the position uncertainty by making a smaller wave packet , you need to add more waves , which means a bigger momentum uncertainty . if you want to know the momentum better , you need a bigger wave packet , which means a bigger position uncertainty . that 's the heisenberg uncertainty principle , first stated by german physicist werner heisenberg back in 1927 . this uncertainty is n't a matter of measuring well or badly , but an inevitable result of combining particle and wave nature . the uncertainty principle is n't just a practical limit on measurment . it 's a limit on what properties an object can have , built into the fundamental structure of the universe itself .
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if we add a third wave , the regions where the waves cancel out get bigger , a fourth and they get bigger still , with the wavier regions becoming narrower . if we keep adding waves , we can make a wave packet with a clear wavelength in one small region . that 's a quantum object with both wave and particle nature , but to accomplish this , we had to lose certainty about both position and momentum .
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adding together multiple waves to make a wave packet means that :
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when the next general election rolls around , who will be eligible to show up at the polls and vote for the president of the united states ? it 's really pretty simple . if you are at least 18 years old , a citizen of the u.s. , and a resident of a state , you can vote , assuming , that is , you are not a felon . seems about right . after all , the united states prides itself on being a democracy , or a government in which the ultimate authority lies with the citizens of the nation . but it was not always this way . in 1789 , george washington won the electoral college with 100 % of the vote , but whose vote was it ? probably not yours . only 6 % of the entire united states population was allowed to vote at all . voting was a right that only white , male property owners were allowed to exercise . by the 1820s and 1830s , the american population was booming from the east coast into the western frontier . frontier farmers were resilient , self-reliant , and mostly ineligible to vote because they did not own land . as these new areas of the nation became states , they typically left out the property requirement for voting . leaders such as andrew jackson , the united state 's first common man president , promoted what he called universal suffrage . of course , by universal suffrage , jackson really meant universal white , male suffrage . all he emphasized was getting rid of the property requirement for voting , not expanding the vote beyond white men . by the 1850s , about 55 % of the adult population was eligible to vote in the u.s. , much better than 6 % , but far from everybody . then , in 1861 , the american civil war began largely over the issue of slavery and states ' rights in the united states . when it was all over , the u.s. ratified the 15th amendment , which promised that a person 's right to vote could not be denied based on race , color , or previous condition as a slave . this meant that black men , newly affirmed as citizens of the u.s. , would now be allowed to vote . of course , laws are far from reality . despite the promise of the 15th amendment , intimidation kept african-americans from exercising their voting rights . states passed laws that limited the rights of african-americans to vote , including things like literacy tests , which were rigged so that not even literate african-americans were allowed to pass , and poll taxes . so , despite the 15th amendment , by 1892 , only about 6 % of black men in mississippi were registered to vote . by 1960 , it was only 1 % . and , of course , women were still totally out of the national voting picture . it was n't until 1920 that the women 's suffrage movement won their 30-year battle , and the 19th amendment finally gave women the vote , well , white women . the restrictions on african-americans , including african-american women , remained . after world war ii , many americans began to question the state of u.s. democracy . how could a nation that fought for freedom and human rights abroad come home and deny suffrage based on race ? the modern civil rights movement began in the 1940s with those questions in mind . after years of sacrifice , bloodshed , and pain , the united states passed the voting rights act of 1965 , finally eliminating restrictions such as literacy tests and protecting the voting rights promised under the 15th amendment to the constitution . now , any citizen over the age of 21 could vote . all seemed well until the united states went to war . when the vietnam war called up all men age 18 and over for the draft , many wondered whether it was fair to send men who could n't vote to war . in 1971 , the 26th amendment to the constitution made all citizens 18 and older eligible to vote , the last major expansion of voting rights in the united states . today , the pool of eligible voters in the u.s. is far broader and more inclusive than ever before in u.s. history . but , of course , it 's not perfect . there are still active efforts to suppress some groups from voting , and only about 60 % of those who can vote do . now that you know all the hard work that went into securing the right to vote , what do you think ? do enough citizens have the right to vote now ? and among those who can vote , why do n't more of them do it ?
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the restrictions on african-americans , including african-american women , remained . after world war ii , many americans began to question the state of u.s. democracy . how could a nation that fought for freedom and human rights abroad come home and deny suffrage based on race ?
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after the civil war , the us ratified the 15th amendment . what did it state ?
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translator : andrea mcdonough reviewer : bedirhan cinar we talk about inventions and innovation as though the best things out there are the internet , ipads , or smart phones . or perhaps more simply , trains , planes , and automobiles . which one is most important , the best , or the greatest ? which one has had the most impact on society ? today the debate would probably be in favor of computer technology , but is it ? well , some would say , `` nope , not really , it 's farming . '' where would we be if we did n't have it ? give up ? we would still be hunting and gathering with little time to invent anything , let alone the internet . that 's right , farming is the seed of civilization . not quite literally , but without early man 's discovery of using seeds to grow grain , we would n't have much of anything we have today . growing your own food changed everything . sure , hunting and gathering worked just fine for tens of thousands of years , but you could n't do much else - no time . but when hunters and gatherers started planting seeds , they began to farm . with farming came animals , and with animals came settling down and staying in one location . so , how does this have anything to do with invention and innovation ? everything . anyone who 's ever farmed , even if it 's planting a half dozen tomato plants in your backyard , knows that you usually harvest way more than you could possibly eat , a surplus . farming yielded plenty of food , with enough to store , trade , and eat . in other words , not everyone needed to be farmers . therefore , this allowed other people , non-farmers , to do other things such as make tools , craft pottery , and build homes . farming and food surpluses led to the division of labor . this is still thousands of years ago , so life was n't easy . but with so many people contributing to the community , small villages began to develop . as the population of villages expanded , so did the needs of the people . things got complicated . but , civilization is just that - advanced , complex societies . and without farming , they would not exist . villages increased in size , eventually becoming the first cities . cities are just one of the basic features of a civilization , the others include central government , system of writing , organized religion , art and architecture , urban planning of roads , bridges , and public works , social classes , and different jobs . developing expertise in various types of occupations allowed for innovative ways of doing things , producing new products , or making advancements in technology . as civilizations became more complex , new ways of doing things were needed . some were out of necessity . others because people had ideas . the sharing of ideas and technology led to the growth of things we readily use today , like the internet . so without farming , we 'd still be hunting and gathering . no video , no computers , and certainly no world wide web .
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therefore , this allowed other people , non-farmers , to do other things such as make tools , craft pottery , and build homes . farming and food surpluses led to the division of labor . this is still thousands of years ago , so life was n't easy .
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what was one of the most important factors as a result of farming that led to the division of labor ?
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you may have heard a lot about how dogs have an incredibly keen sense of smell , and it ’ s true . an average dog ’ s nose is anywhere between ten thousand to one hundred thousand times more sensitive that yours . so how can dogs with their super sense of smell be so interested in their k9 compatriot ’ s rear ends ? well folks , the answer is more complex and interesting thank you think . when a dog smells another dog ’ s butt , it ’ s actually collecting a bunch of information about the other dog – its diet , its gender , its emotional state and so on . think of it kind of like speaking with chemicals . in fact , this butt-sniffing action is just one of many examples of chemical communication in the animal kingdom . but what chemicals are packed in a fido ’ s rear end and where do they come from ? we talked to dr. george preti of the monell chemical senses center in philadelphia . dr. preti currently studies the complexity of human body odors and pheromones . but back in 1975 , he was on the cutting edge of dog butts science . he and his team of researchers examined the anal secretions of dogs and wild coyotes . so on both sides of sparky ’ s back door is a stinky , small pouch called an anal sac . this sac houses glands that excrete the chemicals dogs use to get to know each other . the apocrine gland is most responsible for that “ dog smell ” , but the sebaceous glands also play a part . petri discovered the primary chemical compounds that produce a dog ’ s aroma are trimethylamine and a host of short chain acids . as you might expect , anal sac secretions have a very powerful , sharp odor as a result of the acids inside . but a dog ’ s genetics , diet , and the current state of their immune system can all influence this aroma through chemical changes in the secretions . you ’ d think the smell of dog poop would overpower rover ’ s sensitive snout . but dogs have a second olfactory system in their hyper-sensitive nose called the jacobson ’ s organ . the organ is designed specifically for chemical communication . it has its own set of nerves that lead directly to the brain , so there ’ s absolutely no interference from other odors . the same organ is used when a dog sniffs a fire hydrant , or anywhere else there happens to be dog pee . so , there you have it folks . your precious pet isn ’ t obsessed with other dog ’ s butts per say . they ’ re just getting to know each other in a professional aromatic way . hey speaking of aroma , you should check out this video on why bacon smells so good , because bacon is to people , as butts are to dogs . thanks for watching folks , don ’ t forget to subscribe and we ’ ll see you again soon .
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you may have heard a lot about how dogs have an incredibly keen sense of smell , and it ’ s true . an average dog ’ s nose is anywhere between ten thousand to one hundred thousand times more sensitive that yours . so how can dogs with their super sense of smell be so interested in their k9 compatriot ’ s rear ends ?
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an average dog 's nose is anywhere from ____ to ____ times more sensitive than a human 's nose .
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vsauce , i ’ m jake and thank you for visiting because i have been stuck in this chair for weeks . why you ask ? let me tell you ! it is because of this ! what is that ? well my dear friend , as you may know i have cancer and to try and stop it from spreading , they removed a lot of flesh , muscle , tissue and bone and replaced it with something else…and that got me thinking , about what makes you you . which then in turn got me thinking about paradoxes . specifically logical paradoxes or thought experiments . ya know there is one in particular that pertains to the removal and replacement of certain things…let 's go outside quick little side note : i also figured out teleportation but we ’ ll discuss that later…ya know you should come out here too . so we can discuss the ship of theseus ! the ship of theseus is pretty straightforward as far as logical paradoxes go . let 's say we have a ship , and it 's a very nice ship . but after a while we end up replacing all the wood and then a while later we replace the sails , then a while later we replace the hooks . is it still the same ship ? or is it a new ship ? a different ship ? let ’ s go a step further . let ’ s say we kept all the pieces of this ship that we replaced and used them to make another ship ... an identical one . is this one the original or is this one ? or are they both not original ? what makes something truly original ? i need some sand . here i have what i would consider a heap of sand which leads us into our next logical paradox . the sorites paradox . sorites in ancient greek meaning heap . so , we have our heap , right ? but what happens if we take away a grain of sand ? well , it 's still a heap . but then we take away another grain… still a heap . but then we take another , and another , until we get this . is this a heap ? what about this ? or this ? if we remove a grain until only one is left…is this still a heap ? at what point do we no longer consider it a heap ? let ’ s reverse it . we start with a single grain of sand . obviously not what we would call a heap . but then we add a grain and another , and another . when does it become a heap of sand ? ya know , instead of using objects as our examples , let ’ s discuss a paradox that instead , uses words . we interact with words every day but today we are going to focus on just two words , autological and heterological , these are essential for the grelling-nelson paradox . an autological word is a word that describes itself . for example : pronounceable is pronounceable , polysyllabic is polysyllabic , and a noun is a noun . then there is heterological where a word does not describe itself . for example : purple is not purple , triangle is not a triangle and hyphenated is not hyphenated . the paradox comes into play when we ask the question : is the word “ heterological ” heterological ? if you say no , then heteorological does not describe itself . and if it ’ s not heterological then it must be autological and describe itself . but if it is autological then heterological describes itself and therefor heterological is heterological . paradox . if you say yes , heterological does not describe itself then that means heterological is not heterological . paradox . let ’ s try something . let ’ s combine aspects of the ship of theseus and the sorites paradox and apply it to ourselves . even though part of my leg was replaced i am still me , right ? if my entire leg were removed , i ’ d still be me . so at what point am i no longer myself ? how much would have to be removed for you to no longer be you ? or is what makes us us our memories of who we are and of who we were ? for example , you are different than when you were a baby . obviously you are taller , a little bit heavier , you have different hair , different teeth , and all of your cells have been replaced since birth . i mean your personality has changed . your opinions have changed…so how are you the same person ? ya know ... maybe we should lay off the teleportation for a little not just because of that but also because i 've been thinking of something ... the teletransportation paradox . let ’ s say we have a machine that can teleport you from here to there . in order to transmit you though , the machine kills you and instantly breaks you down into all the atoms that once made you up . it then transmits all the data of what you were to another machine in a different location which remakes you . putting different atoms in the right spot . so the question is , is the person who went into the machine the same person coming out of the other machine ? you have the same memories , the same thoughts , but everything that physically makes you is different . you ’ d remember everything up to being teleported and reemerging on the other side - everything in between would be lost . so , is it your identity , your emotions , feelings and is it your thoughts that make you you ? ya know , you should come a little bit closer . when you wake up in the morning , how do you know that you ’ re the same person as who went to sleep ? how do i know that when i close my eyes , is the same jake opening them ? maybe every time we open our eyes we are being created again and again from the idea of who we are…from our sense of identity . and , as always , thanks for watching .
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and if it ’ s not heterological then it must be autological and describe itself . but if it is autological then heterological describes itself and therefor heterological is heterological . paradox .
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explain why trying to define the word `` heterological '' as heterological or autological creates a logical paradox .
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what do an ancient greek philosopher and a 19th century quaker have in common with nobel prize-winning scientists ? although they are separated over 2,400 years of history , each of them contributed to answering the eternal question : what is stuff made of ? it was around 440 bce that democritus first proposed that everything in the world was made up of tiny particles surrounded by empty space . and he even speculated that they vary in size and shape depending on the substance they compose . he called these particles `` atomos , '' greek for indivisible . his ideas were opposed by the more popular philosophers of his day . aristotle , for instance , disagreed completely , stating instead that matter was made of four elements : earth , wind , water and fire , and most later scientists followed suit . atoms would remain all but forgotten until 1808 , when a quaker teacher named john dalton sought to challenge aristotelian theory . whereas democritus 's atomism had been purely theoretical , dalton showed that common substances always broke down into the same elements in the same proportions . he concluded that the various compounds were combinations of atoms of different elements , each of a particular size and mass that could neither be created nor destroyed . though he received many honors for his work , as a quaker , dalton lived modestly until the end of his days . atomic theory was now accepted by the scientific community , but the next major advancement would not come until nearly a century later with the physicist j.j. thompson 's 1897 discovery of the electron . in what we might call the chocolate chip cookie model of the atom , he showed atoms as uniformly packed spheres of positive matter filled with negatively charged electrons . thompson won a nobel prize in 1906 for his electron discovery , but his model of the atom did n't stick around long . this was because he happened to have some pretty smart students , including a certain ernest rutherford , who would become known as the father of the nuclear age . while studying the effects of x-rays on gases , rutherford decided to investigate atoms more closely by shooting small , positively charged alpha particles at a sheet of gold foil . under thompson 's model , the atom 's thinly dispersed positive charge would not be enough to deflect the particles in any one place . the effect would have been like a bunch of tennis balls punching through a thin paper screen . but while most of the particles did pass through , some bounced right back , suggesting that the foil was more like a thick net with a very large mesh . rutherford concluded that atoms consisted largely of empty space with just a few electrons , while most of the mass was concentrated in the center , which he termed the nucleus . the alpha particles passed through the gaps but bounced back from the dense , positively charged nucleus . but the atomic theory was n't complete just yet . in 1913 , another of thompson 's students by the name of niels bohr expanded on rutherford 's nuclear model . drawing on earlier work by max planck and albert einstein he stipulated that electrons orbit the nucleus at fixed energies and distances , able to jump from one level to another , but not to exist in the space between . bohr 's planetary model took center stage , but soon , it too encountered some complications . experiments had shown that rather than simply being discrete particles , electrons simultaneously behaved like waves , not being confined to a particular point in space . and in formulating his famous uncertainty principle , werner heisenberg showed it was impossible to determine both the exact position and speed of electrons as they moved around an atom . the idea that electrons can not be pinpointed but exist within a range of possible locations gave rise to the current quantum model of the atom , a fascinating theory with a whole new set of complexities whose implications have yet to be fully grasped . even though our understanding of atoms keeps changing , the basic fact of atoms remains , so let 's celebrate the triumph of atomic theory with some fireworks . as electrons circling an atom shift between energy levels , they absorb or release energy in the form of specific wavelengths of light , resulting in all the marvelous colors we see . and we can imagine democritus watching from somewhere , satisfied that over two millennia later , he turned out to have been right all along .
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but while most of the particles did pass through , some bounced right back , suggesting that the foil was more like a thick net with a very large mesh . rutherford concluded that atoms consisted largely of empty space with just a few electrons , while most of the mass was concentrated in the center , which he termed the nucleus . the alpha particles passed through the gaps but bounced back from the dense , positively charged nucleus .
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what occurred during rutherford ’ s experiment that lead to his discovery of the nucleus ?
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in the 16th century , the mathematician robert recorde wrote a book called `` the whetstone of witte '' to teach english students algebra . but he was getting tired of writing the words `` is equal to '' over and over . his solution ? he replaced those words with two parallel horizontal line segments because the way he saw it , no two things can be more equal . could he have used four line segments instead of two ? of course . could he have used vertical line segments ? in fact , some people did . there 's no reason why the equals sign had to look the way it does today . at some point , it just caught on , sort of like a meme . more and more mathematicians began to use it , and eventually , it became a standard symbol for equality . math is full of symbols . lines , dots , arrows , english letters , greek letters , superscripts , subscripts . it can look like an illegible jumble . it 's normal to find this wealth of symbols a little intimidating and to wonder where they all came from . sometimes , as recorde himself noted about his equals sign , there 's an apt conformity between the symbol and what it represents . another example of that is the plus sign for addition , which originated from a condensing of the latin word et meaning and . sometimes , however , the choice of symbol is more arbitrary , such as when a mathematician named christian kramp introduced the exclamation mark for factorials just because he needed a shorthand for expressions like this . in fact , all of these symbols were invented or adopted by mathematicians who wanted to avoid repeating themselves or having to use a lot of words to write out mathematical ideas . many of the symbols used in mathematics are letters , usually from the latin alphabet or greek . characters are often found representing quantities that are unknown , and the relationships between variables . they also stand in for specific numbers that show up frequently but would be cumbersome or impossible to fully write out in decimal form . sets of numbers and whole equations can be represented with letters , too . other symbols are used to represent operations . some of these are especially valuable as shorthand because they condense repeated operations into a single expression . the repeated addition of the same number is abbreviated with a multiplication sign so it does n't take up more space than it has to . a number multiplied by itself is indicated with an exponent that tells you how many times to repeat the operation . and a long string of sequential terms added together is collapsed into a capital sigma . these symbols shorten lengthy calculations to smaller terms that are much easier to manipulate . symbols can also provide succinct instructions about how to perform calculations . consider the following set of operations on a number . take some number that you 're thinking of , multiply it by two , subtract one from the result , multiply the result of that by itself , divide the result of that by three , and then add one to get the final output . without our symbols and conventions , we 'd be faced with this block of text . with them , we have a compact , elegant expression . sometimes , as with equals , these symbols communicate meaning through form . many , however , are arbitrary . understanding them is a matter of memorizing what they mean and applying them in different contexts until they stick , as with any language . if we were to encounter an alien civilization , they 'd probably have a totally different set of symbols . but if they think anything like us , they 'd probably have symbols . and their symbols may even correspond directly to ours . they 'd have their own multiplication sign , symbol for pi , and , of course , equals .
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in fact , some people did . there 's no reason why the equals sign had to look the way it does today . at some point , it just caught on , sort of like a meme .
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what is the best way to become familiar with mathematical notation ?
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way before the first selfie , the ancient greeks and romans had a myth about someone a little too obsessed with his own image . in one telling , narcissus was a handsome guy wandering the world in search of someone to love . after rejecting a nymph named echo , he caught a glimpse of his own reflection in a river , and fell in love with it . unable to tear himself away , narcissus drowned . a flower marked the spot of where he died , and we call that flower the narcissus . the myth captures the basic idea of narcissism , elevated and sometimes detrimental self-involvement . but it 's not just a personality type that shows up in advice columns . it 's actually a set of traits classified and studied by psychologists . the psychological definition of narcissism is an inflated , grandiose self-image . to varying degrees , narcissists think they 're better looking , smarter , and more important than other people , and that they deserve special treatment . psychologists recognize two forms of narcissism as a personality trait : grandiose and vulnerable narcissism . there 's also narcissistic personality disorder , a more extreme form , which we 'll return to shortly . grandiose narcissism is the most familiar kind , characterized by extroversion , dominance , and attention seeking . grandiose narcissists pursue attention and power , sometimes as politicians , celebrities , or cultural leaders . of course , not everyone who pursues these positions of power is narcissistic . many do it for very positive reasons , like reaching their full potential , or helping make people 's lives better . but narcissistic individuals seek power for the status and attention that goes with it . meanwhile , vulnerable narcissists can be quiet and reserved . they have a strong sense of entitlement , but are easily threatened or slighted . in either case , the dark side of narcissism shows up over the long term . narcissists tend to act selfishly , so narcissistic leaders may make risky or unethical decisions , and narcissistic partners may be dishonest or unfaithful . when their rosy view of themselves is challenged , they can become resentful and aggressive . it 's like a disease where the sufferers feel pretty good , but the people around them suffer . taken to the extreme , this behavior is classified as a psychological disorder called narcissistic personality disorder . it affects one to two percent of the population , more commonly men . it is also a diagnosis reserved for adults . young people , especially children , can be very self-centered , but this might just be a normal part of development . the fifth edition of the american psychiatric association 's diagnostic and statistical manual describes several traits associated with narcissistic personality disorder . they include a grandiose view of oneself , problems with empathy , a sense of entitlement , and a need for admiration or attention . what makes these trait a true personality disorder is that they take over people 's lives and cause significant problems . imagine that instead of caring for your spouse or children , you used them as a source of attention or admiration . or imagine that instead of seeking constructive feedback about your performance , you instead told everyone who tried to help you that they were wrong . so what causes narcissism ? twin studies show a strong genetic component , although we do n't know which genes are involved . but environment matters , too . parents who put their child on a pedestal can foster grandiose narcissism . and cold , controlling parents can contribute to vulnerable narcissism . narcissism also seems to be higher in cultures that value individuality and self-promotion . in the united states , for example , narcissism as a personality trait has been rising since the 1970s , when the communal focus of the 60s gave way to the self-esteem movement and a rise in materialism . more recently , social media has multiplied the possibilities for self-promotion , though it 's worth noting that there 's no clear evidence that social media causes narcissism . rather , it provides narcissists a means to seek social status and attention . so can narcissists improve on those negative traits ? yes ! anything that promotes honest reflection on their own behavior and caring for others , like psychotherapy or practicing compassion towards others , can be helpful . the difficulty is it can be challenging for people with narcissistic personality disorder to keep working at self-betterment . for a narcissist , self-reflection is hard from an unflattering angle .
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it 's like a disease where the sufferers feel pretty good , but the people around them suffer . taken to the extreme , this behavior is classified as a psychological disorder called narcissistic personality disorder . it affects one to two percent of the population , more commonly men .
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narcissistic personality disorder is :
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the biggest kidney stone on record weighed more than a kilogram and was 17 centimeters in diameter . the patient did n't actually swallow a stone the size of a coconut . kidney stones form inside the body , but unfortunately , they 're extremely painful to get out . a kidney stone is a hard mass of crystals that can form in the kidneys , ureters , bladder , or urethra . urine contains compounds that consist of calcium , sodium , potassium , oxalate , uric acid , and phosphate . if the levels of these particles get too high , or if urine becomes too acidic or basic , the particles can clump together and crystallize . unless the problem is addressed , the crystals will gradually grow over a few weeks , months , or even years , forming a detectable stone . calcium oxalate is the most common type of crystal to form this way , and accounts for about 80 % of kidney stones . less common kidney stones are made of calcium phosphate , or uric acid . a slightly different type of stone made of the minerals magnesium ammonium phosphate , or struvite , can be caused by bacterial infection . and even rarer stones can result from genetic disorders or certain medications . a kidney stone can go undetected until it starts to move . when a stone travels through the kidney and into the ureter , its sharp edges scratch the walls of the urinary tract . nerve endings embedded in this tissue transmit excruciating pain signals through the nervous system . and the scratches can send blood flowing into the urine . this can be accompanied by symptoms of nausea , vomiting , and a burning sensation while urinating . if a stone gets big enough to actually block the flow of urine , it can create an infection , or back flow , and damage the kidneys themselves . but most kidney stones do n't become this serious , or even require invasive treatment . masses less than five millimeters in diameter will usually pass out of the body on their own . a doctor will often simply recommend drinking large amounts of water to help speed the process along , and maybe taking some pain killers . if the stone is slightly larger , medications like alpha blockers can help by relaxing the muscles in the ureter and making it easier for the stone to get through . another medication called potassium citrate can help dissolve the stones by creating a less acidic urine . for medium-sized stones up to about ten millimeters , one option is pulverizing them with soundwaves . extracorporeal shock wave lithotripsy uses high-intensity pulses of focused ultrasonic energy aimed directly at the stone . the pulses create vibrations inside the stone itself and small bubbles jostle it . these combined forces crush the stone into smaller pieces that can pass out of the body more easily . but zapping a stone with sound does n't work as well if it 's simply too big . so sometimes , more invasive treatments are necessary . a rigid tube called a stent can be placed in the ureter to expand it . optical fibers can deliver laser pulses to break up the stone . stones can also be surgically removed through an incision in the patient 's back or groin . what about just avoiding kidney stones in the first place ? for people prone to them , their doctor may recommend drinking plenty of water , which dilutes the calcium oxalate and other compounds that eventually build up into painful stones . foods like potato chips , spinach , rhubarb , and beets are high in oxalate , so doctors might advise limiting them . even though calcium is often found in stones , calcium in foods and beverages can actually help by binding to oxalate in the digestive tract before it can be absorbed and reach the kidneys . if you do end up with a kidney stone , you 're not alone . data suggests that rates are rising , but that world record probably wo n't be broken any time soon .
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if a stone gets big enough to actually block the flow of urine , it can create an infection , or back flow , and damage the kidneys themselves . but most kidney stones do n't become this serious , or even require invasive treatment . masses less than five millimeters in diameter will usually pass out of the body on their own .
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what is the best treatment for small size (
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the most basic function of bodily fat is self-storage of food reserves . in prehistoric times , natural selection favored genotypes that could endure harsh conditions by stocking the most fat . with chronic malnutrition being the norm for most of human history , genetics evolved to favor fat storage . so when did body fat become problematic ? the negative impacts of being overweight were not even noted in medical literature until as late as the 18th century . then , technological advances coupled with public health measures resulted in the betterment of the quantity , quality , and variety of food . sustained abundance of good food enabled a healthier population to boom economically . output increased , and with it , leisure time and waistlines . by the mid 19th century , being excessively overweight , or obese , was recognized as a cause of ill health , and another century later , declared deadly . what is the distinction between being overweight and being obese ? a calculation called the bmi breaks it down for us . for example , if someone weighs 65 kilgorams and is 1.5 meters tall , they have a bmi of about 29 . obesity is a condition of excess body fat that occurs when a person 's bmi is above 30 , just over the overweight range of 25 to 29.9 . while bmi can be a helpful estimate of healthy weight , actual body fat percentage can only really be determined by also considering information like waist circumference and muscle mass . athletes , for instance , have a naturally higher bmi . so how does a person become obese ? at its most basic , obesity is caused by energy imbalance . if the energy input from calories is greater than the energy output from physical activity , the body stores the extra calories as fat . in most cases , this imbalance comes from a combination of circumstances and choices . adults should be getting at least 2.5 hours of exercise each week , and children a whole hour per day . but globally , one in four adults and eight out of ten adolescents are n't active enough . calorie-dense processed foods and growing portion sizes coupled with pervasive marketing lead to passive overeating . and scarce resources , and a lack of access to healthy , affordable foods creates an even greater risk in disadvantaged communities . yet , our genetic makeup also plays a part . studies on families and on separated twins have shown a clear causal hereditary relationship to weight gain . recent studies have also found a link between obesity and variations in the bacteria species that live in our digestive systems . no matter the cause , obesity is an escalating global epidemic . it substantially raises the probability of diseases , like diabetes , heart disease , stroke , high blood pressure , and cancer . it affects virtually all ages , genders , and socioeconomic groups in both developed and developing countries . with a 60 % rise in child obesity globally over just two decades , the problem is too significant to ignore . once a person is obese , the climb to recovery becomes progressively steeper . hormonal and metabolic changes reduce the body 's response to overeating . after losing weight , a formerly overweight person burns less calories doing the same exercises as a person who is naturally the same weight , making it much more difficult to shed the excess fat . and as people gain weight , damage to signaling pathways makes it increasingly difficult for the brain to measure food intake and fat storage . there is , however , some evidence that well-monitored , long-term changes in behavior can lead to improvements in obesity-related health issues . and weight loss from sustained lifestyle changes , or invasive treatments like bariatric surgery , can improve insulin resistance and decrease inflammation . what was once an advantage for survival is now working against us . as the world 's population continues to slow down and get bigger , moving and consciously eating our way towards a healthier weight is essential to our overall well-being . and with the epidemic affecting every country in the world for different socioeconomic reasons , obesity can not be seen as an isolated issue . more global measures for prevention are essential to manage the weight of the world .
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athletes , for instance , have a naturally higher bmi . so how does a person become obese ? at its most basic , obesity is caused by energy imbalance .
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how does a person become obese ?
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nestled in the tissues of your neck is a small unassuming organ that wields enormous power over your body . it 's called the thyroid . like the operations manager in a company , its role is to make sure that the cells in your body are working properly . it does that by using hormones to deliver messages to every single one of them . this high-ranking organ is made up of lobules that each contains smaller cells called follicles , which store the hormones the thyroid sends out into your blood . two of the most important hormones it produces are thyroxine and triiodothyronine , or t3 and t4 . as messengers , the hormone 's job is to instruct every cell in the body when to consume oxygen and nutrients . that maintains the body 's metabolism , the series of reactions our cells perform to provide us with energy . this hormonal notification from the thyroid gets the heart pumping more efficiently , and makes our cells break down nutrients faster . when you need more energy , the thyroid helps by sending out hormones to increase metabolism . ultimately , the thyroid allows our cells to use energy , grow and reproduce . the thyroid is controlled by the pituitary gland , a hormonal gland deep in the brain that oversees the thyroid 's tasks , making sure it knows when to send out its messengers . the pituitary 's role is to sense if hormone levels in the blood are too low or too high , in which case it sends out instructions in the form of the thyroid- stimulating hormone . even in this tightly controlled system , however , management sometimes slips up . certain diseases , growths in the thryoid or chemical imbalances in the body can confuse the organ and make it deaf to the pituitary 's guiding commands . the first problem this causes is hyperthyroidism , which happens when the organ sends out too many hormones . that means the cells are overloaded with instructions to consume nutrients and oxygen . they become overactive as a result , meaning a person with hyperthyroidism experiences a higher metabolism signaled by a faster heartbeat , constant hunger , and rapid weight loss . they also feel hot , sweaty , anxious , and find it difficult to sleep . the opposite problem is hypothyroidism , which happens when the thyroid sends out too few hormones , meaning the body 's cells do n't have as many messengers to guide them . in response , cells grow listless and metabolism slows . people with hypothyroidism see symptoms in weight gain , sluggishness , sensitivity to cold , swollen joints and feeling low . luckily , there are medical treatments that can help trigger the thyroid 's activities again , and bring the body back to a steady metabolic rate . for such a little organ , the thyroid wields an awful lot of power . but a healthy thyroid manages our cells so effectively that it can keep us running smoothly without us even noticing it 's there .
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nestled in the tissues of your neck is a small unassuming organ that wields enormous power over your body . it 's called the thyroid . like the operations manager in a company , its role is to make sure that the cells in your body are working properly .
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imagine you had an over-active or underactive thyroid . list all the reasons why this would be both unpleasant , and unhealthy , for you .
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light is the fastest thing we know . it 's so fast that we measure enormous distances by how long it takes for light to travel them . in one year , light travels about 6,000,000,000,000 miles , a distance we call one light year . to give you an idea of just how far this is , the moon , which took the apollo astronauts four days to reach , is only one light-second from earth . meanwhile , the nearest star beyond our own sun is proxima centauri , 4.24 light years away . our milky way is on the order of 100,000 light years across . the nearest galaxy to our own , andromeda , is about 2.5 million light years away space is mind-blowingly vast . but wait , how do we know how far away stars and galaxies are ? after all , when we look at the sky , we have a flat , two-dimensional view . if you point you finger to one star , you ca n't tell how far the star is , so how do astrophysicists figure that out ? for objects that are very close by , we can use a concept called trigonometric parallax . the idea is pretty simple . let 's do an experiment . stick out your thumb and close your left eye . now , open your left eye and close your right eye . it will look like your thumb has moved , while more distant background objects have remained in place . the same concept applies when we look at the stars , but distant stars are much , much farther away than the length of your arm , and the earth is n't very large , so even if you had different telescopes across the equator , you 'd not see much of a shift in position . instead , we look at the change in the star 's apparent location over six months , the halfway point of the earth 's yearlong orbit around the sun . when we measure the relative positions of the stars in summer , and then again in winter , it 's like looking with your other eye . nearby stars seem to have moved against the background of the more distant stars and galaxies . but this method only works for objects no more than a few thousand light years away . beyond our own galaxy , the distances are so great that the parallax is too small to detect with even our most sensitive instruments . so at this point we have to rely on a different method using indicators we call standard candles . standard candles are objects whose intrinsic brightness , or luminosity , we know really well . for example , if you know how bright your light bulb is , and you ask your friend to hold the light bulb and walk away from you , you know that the amount of light you receive from your friend will decrease by the distance squared . so by comparing the amount of light you receive to the intrinsic brightness of the light bulb , you can then tell how far away your friend is . in astronomy , our light bulb turns out to be a special type of star called a cepheid variable . these stars are internally unstable , like a constantly inflating and deflating balloon . and because the expansion and contraction causes their brightness to vary , we can calculate their luminosity by measuring the period of this cycle , with more luminous stars changing more slowly . by comparing the light we observe from these stars to the intrinsic brightness we 've calculated this way , we can tell how far away they are . unfortunately , this is still not the end of the story . we can only observe individual stars up to about 40,000,000 light years away , after which they become too blurry to resolve . but luckily we have another type of standard candle : the famous type 1a supernova . supernovae , giant stellar explosions are one of the ways that stars die . these explosions are so bright , that they outshine the galaxies where they occur . so even when we ca n't see individual stars in a galaxy , we can still see supernovae when they happen . and type 1a supernovae turn out to be usable as standard candles because intrinsically bright ones fade slower than fainter ones . through our understanding of this relationship between brightness and decline rate , we can use these supernovae to probe distances up to several billions of light years away . but why is it important to see such distant objects anyway ? well , remember how fast light travels . for example , the light emitted by the sun will take eight minutes to reach us , which means that the light we see now is a picture of the sun eight minutes ago . when you look at the big dipper , you 're seeing what it looked like 80 years ago . and those smudgy galaxies ? they 're millions of light years away . it has taken millions of years for that light to reach us . so the universe itself is in some sense an inbuilt time machine . the further we can look back , the younger the universe we are probing . astrophysicists try to read the history of the universe , and understand how and where we come from . the universe is constantly sending us information in the form of light . all that remains if for us to decode it .
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through our understanding of this relationship between brightness and decline rate , we can use these supernovae to probe distances up to several billions of light years away . but why is it important to see such distant objects anyway ? well , remember how fast light travels .
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which of the following is not used to obtain distances of astronomical objects ?
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take a moment to read the following . how was that ? frustrating ? slow ? what were those sentences about ? they 're actually a simulation of the experience of dyslexia , designed to make you decode each word . those with dyslexia experience that laborious pace every time they read . when most people think of dyslexia , they think of seeing letters and words backwards , like seeing `` b '' as `` d '' and vice versa , or they might think people with dyslexia see `` saw '' as `` was '' . the truth is people with dyslexia see things the same way as everyone else . dyslexia is caused by a phonological processing problem , meaning people affected by it have trouble not with seeing language but with manipulating it . for example , if you heard the word cat and then someone asked you , `` remove the 'c ' , '' what word would you have left ? at . this can be difficult for those with dyslexia . given a word in isolation , like fantastic , students with dyslexia need to break the word into parts to read it : fan , tas , tic . time spent decoding makes it hard to keep up with peers and gain sufficient comprehension . spelling words phonetically , like s-t-i-k for stick and f-r-e-n-s for friends is also common . these difficulties are more widespread and varied than commonly imagined . dyslexia affects up to one in five people . it occurs on a continuum . one person might have mild dyslexia while the next person has a profound case of it . dyslexia also runs in families . it 's common to see one family member who has trouble spelling while another family member has severe difficulty decoding even one syllable words , like catch . the continuum and distribution of dyslexia suggests a broader principle to bear in mind as we look at how the brains of those with dyslexia process language . neurodiversity is the idea that because all our brains show differences in structure and function , we should n't be so quick to label every deviation from `` the norm '' as a pathological disorder or dismiss people living with these variations as `` defective . '' people with neurobiological variations like dyslexia , including such creative and inventive individuals as picasso , muhammad ali , whoopi goldberg , steven spielberg , and cher , clearly have every capacity to be brilliant and successful in life . so , here 's the special way the brains of those with dyslexia work . the brain is divided into two hemispheres . the left hemisphere is generally in charge of language and , ultimately , reading , while the right typically handles spatial activities . fmri studies have found that the brains of those with dyslexia rely more on the right hemisphere and frontal lobe than the brains of those without it . this means , when they read a word , it takes a longer trip through their brain and can get delayed in the frontal lobe . because of this neurobiological glitch , they read with more difficulty . but those with dyslexia can physically change their brain and improve their reading with an intensive , multi-sensory intervention that breaks the language down and teaches the reader to decode based on syllable types and spelling rules . the brains of those with dyslexia begin using the left hemisphere more efficiently while reading , and their reading improves . the intervention works because it locates dyslexia appropriately as a functional variation in the brain , which , naturally , shows all sorts of variations from one person to another . neurodiversity emphasizes this spectrum of brain function in all humans and suggests that to better understand the perspectives of those around us , we should try not only to see the world through their eyes but understand it through their brains .
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one person might have mild dyslexia while the next person has a profound case of it . dyslexia also runs in families . it 's common to see one family member who has trouble spelling while another family member has severe difficulty decoding even one syllable words , like catch .
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explain the cause of dyslexia .
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hi , i 'm john green , this is crash course us history and today we 're going to talk about what america 's best at : war . [ patriotic rock music ] uh , mr. green , the united states has actually only declared war 5 times in the last 230 years . oh me from the the past , you sniveling literalist . well today we 're going to talk about america 's first declared war , the war of 1812 , so called because historians are terrible at naming things . i mean the could have called it the revolutionary war : part deux , or the canadian cataclysm , or the war to facilitate future wars . but no , they just named it after the year it started . [ theme music ] i know this disappoints the military historians among you , but as usual , we 're gon na spend more time talking about the causes and effects of the war than the actual , like , killing parts , because ultimately it 's the ambiguity of the war of 1812 that makes it so interesting . the reason most often given for the war of 1812 was the british impressment of american sailors , whereby american sailors would be kidnapped and basically forced into british servitude . this disrupted american shipping and also seems like a reasonably obvious violation of american sovereignty , but it 's a little more complicated than that . first of all , there were many thousands of british sailors working aboard american ships so many of the sailors that the british captured were in fact british . which gets to the large point that citizenship at the time was a pretty slippery concept especially on the high seas . like , papers were often forged , and many sailors identified supposed american-ness through tattoos of like eagles and flags . and there were several reasons why a british sailor might like to become , or pretend to be , an american , including that the brits at the time were fighting napoleon in what historians , in their infinite creativity , called the napoleonic wars . and on that topic , britain 's impressment policy allowed them both to disrupt american shipping to france and get new british sailors to strengthen their war effort , which was annoying to the americans on a couple levels especially the french-loving republicans , which is a phrase that you do n't hear very often anymore . another reason often given for the war , was america 's crazy conspiratorial anglophobia . there was even a widespread rumor that british agents were buying up connecticut sheep in order to sabotage the textile industry , lest you worry that america 's fascination with conspiracy theories is new . so those pushing for war were known as war hawks , and the most famous among them was kentucky 's henry clay . they took the impressment of sailors as an affront to american national honor , but they also complained that britain 's actions were an affront to free trade , by which they meant america 's ability to trade with europeans other than great britain . and to be fair , the british were trying to regulate american trade . they even passed the orders in counsel which required american ships to dock in britain and pay tax before trading with other european nations . britain , we were an independent nation ! you ca n't do that kind of stuff ! we have a special relationship but it 's not that special ! but the problem with saying that this caused the war was that the orders had been in effect for five years before the war started . and they were rescinded in 1812 before the us declared war . although , admittedly , we did n't know about it because it did n't reach us until after we declared . there was no twitter . another reason for the war was canada . that 's right canada , american 's wanted you and who can blame them we your excellent healthcare and your hockey and your first rate national anthem . stan this is fun but enough with the # 1812problems . according to the virginia congressman john randolph , `` agrarian cupidity not maritime rights urges the war . we have heard but one word : canada , canada , canada . '' i 'm not here to criticize you john randolph but that 's actually three words . now some historians disagree with this but the relentless pursuit of new land certainly fits in with the jeffersonian model of an agrarian republic . and there 's another factor that figured into america 's decision to go to war : expansion into territory controlled by native americans . oh , it 's time for the mystery document ? the rules here are simple : i try to guess the author of the mystery document . usually i 'm wrong and i get shocked . all right , let ’ s see what we got here . `` you want , by your distinctions of indian tribes , in allotting to each a particular tract of land , to make them to war with each other . you never see an indian come and endeavor to make the white people do so . '' it 's tecumseh . drop the mic ... [ dinging noise ] is something that i would do except that the mic is actually attached to my shirt so there 's n– there 's no drama in this . clearly a native american criticism of white people , and i happen to know that that particular one comes from tecumseh and i do n't get shocked today . so it should n't come as a surprise that americans were continuing to push westward into territories where indians were living . i mean , this was a big reason for the louisiana purchase after all . by the beginning of the war , more than 400,000 settlers had moved into territories west of the original 13 colonies and they outnumbered american indians by a significant margin . some native groups responded with a measure of assimilation . cherokees like john ross wanted to become more `` civilized '' , that is , more white and farmer-y . and some of them did even adopt such civilized practices as written languages and slavery , the most civilized practice of all . [ sigh ] people are always like , `` why are n't you more celebratory of american history ? '' well , why is n't there more to celebrate ? but other indians wanted to resist . the best known of these were the aforementioned tecumseh and his brother tensk – stan , can you just put it on the screen ? [ tenskwatawa on screen ] yes . let 's just enjoy looking at that . right , that 's just for all you visual learners . so he was also known as the prophet , because of his religious teachings , and also because of the pronunciation issues . the prophet encouraged indians , especially those living in and around the settlement of prophetstown , to abandon the ways of the whites , primarily in the form of alcohol and manufactured consumer goods . so stop drinking alcohol and eating refined sugars – this guy sounds like my doctor ! tecumseh was more militant ; attempting to revive neolin 's idea of pan-indianism and actively resisting white settlement . as he put it , `` sell a country , why not sell the air , the great sea , as well as the earth ? did not the great spirit make them all for the use of his children ? '' the americans responded to this reasonable criticism in the traditional manner – with guns . william henry harrison destroyed the native settlement at prophetstown in what would become known as the battle of tippecanoe . he would later ride that fame all the way to the presidency in 1840 and then – spoiler alert : he would give the longest inauguration address ever , catch a cold , and die 40 days later . let that be a lesson to you , american politicians : long speeches ? fatal ! so i just painted a pretty negative picture of the american treatment of the indians – because it was awful . but i have n't mentioned how this relates to the war of 1812 . the americans were receiving reports that the british were encouraging tecumseh , which they probably were . and the important thing to remember here is that the war of 1812 , like the seven years war and the american revolution was also a war against indians . and as in those other two wars , the indians were the biggest losers . and not in the cool way of biggest loser where , like , trainer bob helps you lose weight , but in the really sad way , where your entire civilization gets john c. calhouned . so the war of 1812 was the first time that the united states declared war on anybody . it was also the smallest margin of a declaration of war vote : 79 to 49 in the house and 19 to 13 in the senate . northern states , which relied on trade a lot , did n't want to go to war , while southern and western states , which were more agrarian and wanted expansion to get land for farming and slavery , did . the closeness of the vote reflects a profound ambivalence about the war . as henry adams wrote , `` many nations have gone to war in pure gaiety of the heart , but perhaps the united states were the first to force themselves into a war they dreaded , in the hope that the war itself might create the spirit they lacked . '' do n't worry , henry adams ! in the future we 're gon na get pretty gaiety of heart-ish about war . anyway , as an actual war , the war of 1812 was something of a farce . let 's go to the thought bubble . the us army numbered 10-12 thousand and its officers were sunk into either sloth , ignorance , or habits of intemperate drinking . the us navy had 17 ships . great britain had 1,000 . also , america had very little money , britain collected 40 times more tax revenue than the us . but britain was busy fighting napoleon , which is why they did n't really start kicking america 's butt until 1814 , after napoleon was defeated . napoleon 's defeat was also the practice of impressment , since britain did n't need so many sailors anymore . initially , much of the war consisted of america 's attempts to take canada , which any map will show you went smashingly . americans were confident the canadians would rush to join the us . when marching from detroit , general william hull informed the canadians that , `` you will be emancipated from tyranny and oppression and restored to the dignified station of free men . '' and the canadians were like , `` yeah , we 're okay actually . '' and so the british in canada , with their indian allies , went ahead and captured detroit and then forced hull 's surrender . america 's lack of success in canada was primarily attributable to terrible strategy . they might have succeeded if they 'd taken montreal , but they did n't want to march through northern new york because it was full of federalists who were opposed to the war . instead they concentrated on the west , that is , the area around detroit , where fighting went back and forth . the british found much more success , even seizing washington dc and burning the white house . in the course of the battle , british admiral george cockburn , overseeing the destruction of a newspaper printing house , told the forces that took the city , `` be sure that all the cs are destroyed , so that the rascals can not any longer abuse my name . it 's hard out there for a cockburn . thanks , thought bubble . given these problems it 's amazing there were any american successes , but there were . the battleship uss constitution broke the myth of british naval invincibility when cannonballs bounced off it and earned it the nickname `` old ironsides '' . oliver hazard perry defeated a british fleet , in , of all places , lake erie . at the battle of the thames , william harry harrison defeated tecumseh . and the battle of horseshoe ben showed one of the reasons why indians were defeated when andrew jackson played one group of creeks against another group of creeks and cherokees . 800 indians were killed in that battle . and speaking of jackson , the most notable american victory of the war was the battle of new orleans , which catapulted him to prominence . he lost only 71 men while inflicting 2,036 british casualties . of course , the most memorable thing about the battle is that it took place two weeks after the peace treaty ending the war had been signed . but hey , that 's not jackson 's fault . again – no twitter , # 1815problems . the treaty of ghent , which ended the war , proved just how necessary the war had been : not at all . no territory changed hands when negotiations started . and in august 1814 , the british asked for northern maine , demilitarization of the great lakes , and some territory to create an independent nation for the indians , and the northwest . but none of that happened , not because the u.s. was in a particularly good negotiating position , but it would have been awkward for great britain to carve out pieces of the us , and then tell russia and prussia that they could n't take pieces of europe for themselves to celebrate their victory in the napoleonic wars . there were no provisions in the treaty about impressment or free trade and basically the treaty returned everything to the status quo . so , neither the us or great britain actually won . but the indians suffered significant casualties and gave up even more territory , definitely lost . so with a treaty like that , the war must have had a negligible impact on american history , right ? except , no ; the war of 1812 confirmed that the us would exist . britain would never invade american again ( until 1961 ) . i mean the us were good customers , and great britain was happy to let them trade , as long as that trade was n't helping a french dictator . the war launched andrew jackson 's career and solidified the settlement and conquest of land east of the mississippi river . and our lack of success in canada reinforced canadian nationalism while also ensuring that instead of becoming one great nation , we would forever be canada 's pants . the war also spelled the end of the federalist party , which tried in 1815 with the hartford convention to change the constitution . in retrospect , the hartford convention proposals actually look pretty reasonable . they wanted to eliminate the clause wherein black people were counted as 3/5 of a human , and require a 2/3 congressional majority to declare war . but because they had their convention right before jackson 's victory at new orleans , they only came off looking unpatriotic and out of touch , as the elite so often do . it 's hard to argue that the americans really won the war of 1812 , but we felt like we won , and nothing unleashes national pride like war winning . the nationalistic fervor that emerged in the early 19th century , was , like most things , good news for some and bad news for others . but what ’ s important to remember , regardless of whether you 're an american , is that after 1812 , the united states saw itself not just as an independent nation but as a big player on the world stage . for better and for worse , that 's a gig we 've held onto . and no matter how you feel about america 's international interventions , you need to remember , it did n't begin in afghanistan or even europe ; it started with freakin ' canada . thanks for watching , i 'll see you next week . crash course is produced and directed by stan muller . the script supervisor is meredith danko . our show is written by my high school history teacher raoul meyer and myself . our associate producer is danica johnson . and our graphics team is thought cafe . if you have questions about today 's video , you can ask them in comments , where they will be answered by our team of historians . we also accept suggestions for libertage captions . thanks for watching crash course and as we say in my hometown : do n't forget to be awesome . goodbye ! do n't forget to subscribe !
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so with a treaty like that , the war must have had a negligible impact on american history , right ? except , no ; the war of 1812 confirmed that the us would exist . britain would never invade american again ( until 1961 ) .
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the war of 1812 is responsible for all of the following except :
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you may know that it takes light a zippy eight minutes to reach us from the surface of the sun , so how long do you think it takes light to travel from the sun 's core to its surface ? a few seconds or a minute at most ? well , oddly enough , the answer is many thousands of years . here 's why . photons are produced by the nuclear reactions deep in the core of our sun . as the photons flow out of the core , they interact with matter and lose energy , becoming longer wavelength forms of light . they start out as gamma rays in the core , but end up as x-rays , ultraviolet or visible light as they near the surface . however , that journey is neither simple nor direct . upon being born , each photon travels at a speed of 300,000 kilometers per second until it collides with a proton and is diverted in another direction , acting like a bullet ricocheting off of every charged particle it strikes . the question of how far this photon gets from the center of the sun after each collision is known as the random walk problem . the answer is given by this formula : distance equals step size times the square root of the number of steps . so if you were taking a random walk from your front door with a one meter stride each second , it would take you a million steps and eleven days just to travel one kilometer . so then how long does it take for a photon generated in the center of the sun to reach you ? we know the mass of the sun and can use that to calculate the number of protons within it . let 's assume for a second that all the sun 's protons are evenly spread out , making the average distance between them about 1.0 x 10^-10 meters . to random walk the 690,000 kilometers from the core to the solar surface would then require 3.9 x 10^37 steps , giving a total travel time of 400 billion years . hmm , that ca n't be right . the sun is only 4.6 billion years old , so what went wrong ? two things : the sun is n't actually of uniform density and photons will miss quite a few protons between every collision . in actuality , a photon 's energy , which changes over the course of its journey , determines how likely it is to interact with a proton . on the density question , our models show that the sun has a hot core , where the fusion reactions occur . surrounding that is the radiative zone , followed by the convective zone , which extends all the way to the surface . the material in the core is much denser than lead , while the hot plasma near the surface is a million times less dense with a continuum of densities in between . and here 's the photon-energy relationship . for a photon that carries a small amount of energy , a proton is effectively huge , and it 's much more likely to cause the photon to ricochet . and for a high-energy photon , the opposite is true . protons are effectively tiny . photons start off at very high energies compared to when they 're finally radiated from the sun 's surface . now when we use a computer and a sophisticated solar interior model to calculate the random walk equation with these changing quantities , it spits out the following number : 170,000 years . future discoveries about the sun may refine this number further , but for now , to the best of our understanding , the light that 's hitting your eyes today spent 170,000 years pinballing its way towards the sun 's surface , plus eight miniscule minutes in space . in other words , that photon began its journey two ice ages ago , around the same time when humans first started wearing clothes .
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upon being born , each photon travels at a speed of 300,000 kilometers per second until it collides with a proton and is diverted in another direction , acting like a bullet ricocheting off of every charged particle it strikes . the question of how far this photon gets from the center of the sun after each collision is known as the random walk problem . the answer is given by this formula : distance equals step size times the square root of the number of steps .
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in your own words , describe the random walk problem and sketch a picture of how it works that would help someone else understand it .
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try to measure a circle . the diameter and radius are easy , they 're just straight lines you can measure with a ruler . but to get the circumference , you 'd need measuring tape or a piece of string , unless there was a better way . now , it 's obvious that a circle 's circumference would get smaller or larger along with its diameter , but the relationship goes further than that . in fact , the ratio between the two , the circumference divided by the diameter , will always be the same number , no matter how big or small the circle gets . historians are n't sure when or how this number was first discovered , but it 's been known in some form for almost 4,000 years . estimates of it appear in the works of ancient greek , babylonian , chinese , and indian mathematicians . and it 's even believed to have been used in building the egyptian pyramids . mathematicians estimated it by inscribing polygons in circles . and by the year 1400 , it had been calculated to as far as ten decimal places . so , when did they finally figure out the exact value instead of just estimating ? actually , never ! you see , the ratio of a circle 's circumference to its diameter is what 's known as an irrational number , one that can never be expressed as a ratio of two whole numbers . you can come close , but no matter how precise the fraction is , it will always be just a tiny bit off . so , to write it out in its decimal form , you 'd have an on-going series of digits starting with 3.14159 and continuing forever ! that 's why , instead of trying to write out an infinite number of digits every time , we just refer to it using the greek letter pi . nowadays , we test the speed of computers by having them calculate pi , and quantum computers have been able to calculate it up to two quadrillion digits . people even compete to see how many digits they can memorize and have set records for remembering over 67,000 of them . but for most scientific uses , you only need the first forty or so . and what are these scientific uses ? well , just about any calculations involving circles , from the volume of a can of soda to the orbits of satellites . and it 's not just circles , either . because it 's also useful in studying curves , pi helps us understand periodic or oscillating systems like clocks , electromagnetic waves , and even music . in statistics , pi is used in the equation to calculate the area under a normal distribution curve , which comes in handy for figuring out distributions of standardized test scores , financial models , or margins of error in scientific results . as if that were n't enough , pi is used in particle physics experiments , such as those using the large hadron collider , not only due to its round shape , but more subtly , because of the orbits in which tiny particles move . scientists have even used pi to prove the illusive notion that light functions as both a particle and an electromagnetic wave , and , perhaps most impressively , to calculate the density of our entire universe , which , by the way , still has infinitely less stuff in it than the total number of digits in pi .
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that 's why , instead of trying to write out an infinite number of digits every time , we just refer to it using the greek letter pi . nowadays , we test the speed of computers by having them calculate pi , and quantum computers have been able to calculate it up to two quadrillion digits . people even compete to see how many digits they can memorize and have set records for remembering over 67,000 of them .
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name two other numbers that are as important ( or more important ) than pi .
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you know how sometimes you go to bake a cake but your bananas have all gone rotten , your utensils have rusted , you trip and pour all of your baking soda into the vinegar jug , and then your oven explodes ? my friend , you and your chemical reactions have fallen victim to enthalpy and entropy and , boy , are they forces to be reckoned with . now , your reactants are all products . so , what are these `` e '' words , and what 's their big idea ? let 's start with enthalpy , an increase or decrease of energy during a chemical reaction . every molecule has a certain amount of chemical potential energy stored within the bonds between its atoms . chemicals with more energy are less stable , and thus , more likely to react . let 's visualize the energy flow in a reaction , the combustion of hydrogen and oxygen , by playing a round of crazy golf . our goal is to get a ball , the reactant , up a small rise and down the other much steeper slope . where the hill goes up , we need to add energy to the ball , and where it goes down , the ball releases energy into its surroundings . the hole represents the product , or result of the reaction . when the reaction period ends , the ball is inside the hole , and we have our product : water . this , like when our oven exploded , is an exothermic reaction , meaning that the chemical 's final energy is less than its starting energy , and the difference has been added to the surrounding environment as light and heat . we can also play out the opposite type of reaction , an endothermic reaction , where the final energy is greater than the starting energy . that 's what we were trying to achieve by baking our cake . the added heat from the oven would change the chemical structure of the proteins in the eggs and various compounds in the butter . so that 's enthalpy . as you might suspect , exothermic reactions are more likely to happen than endothermic ones because they require less energy to occur . but there 's another independent factor that can make reactions happen : entropy . entropy measures a chemical 's randomness . here 's an enormous pyramid of golf balls . its ordered structure means it has low entropy . however , when it collapses , we have chaos everywhere , balls bouncing high and wide . so much so that some even go over the hill . this shift to instability , or higher entropy , can allow reactions to happen . as with the golf balls , in actual chemicals this transition from structure to disorder gets some reactants past the hump and lets them start a reaction . you can see both enthalpy and entropy at play when you go to light a campfire to cook dinner . your match adds enough energy to activate the exothermic reaction of combustion , converting the high-energy combustible material in the wood to lower energy carbon dioxide and water . entropy also increases and helps the reaction along because the neat , organized log of wood is now converted into randomly moving water vapor and carbon dioxide . the energy shed by this exothermic reaction powers the endothermic reaction of cooking your dinner . bon appétit !
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so , what are these `` e '' words , and what 's their big idea ? let 's start with enthalpy , an increase or decrease of energy during a chemical reaction . every molecule has a certain amount of chemical potential energy stored within the bonds between its atoms .
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an increase or decrease in energy during a chemical reaction is called _____ .
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many elements of traditional japanese culture , such as cuisine and martial arts , are well-known throughout the world . kabuki , a form of classical theater performance , may not be as well understood in the west but has evolved over 400 years to still maintain influence and popularity to this day . the word kabuki is derived from the japanese verb kabuku , meaning out of the ordinary or bizarre . its history began in early 17th century kyoto , where a shrine maiden named izumo no okuni would use the city 's dry kamo riverbed as a stage to perform unusual dances for passerby , who found her daring parodies of buddhist prayers both entertaining and mesmerizing . soon other troops began performing in the same style , and kabuki made history as japan 's first dramatic performance form catering to the common people . by relying on makeup , or keshou , and facial expressions instead of masks and focusing on historical events and everyday life rather than folk tales , kabuki set itself apart from the upper-class dance theater form known as noh and provided a unique commentary on society during the edo period . at first , the dance was practiced only by females and commonly referred to as onna-kabuki . it soon evolved to an ensemble performance and became a regular attraction at tea houses , drawing audiences from all social classes . at this point , onna-kabuki was often risque as geishas performed not only to show off their singing and dancing abilities but also to advertise their bodies to potential clients . a ban by the conservative tokugawa shogunate in 1629 led to the emergence of wakashu-kabuki with young boys as actors . but when this was also banned for similar reasons , there was a transition to yaro-kabuki , performed by men , necessitating elaborate costumes and makeup for those playing female roles , or onnagata . attempts by the government to control kabuki did n't end with bans on the gender or age of performers . the tokugawa military group , or bakufu , was fueled by confucian ideals and often enacted sanctions on costume fabrics , stage weaponry , and the subject matter of the plot . at the same time , kabuki became closely associated with and influenced by bunraku , an elaborate form of puppet theater . due to these influences , the once spontaneous , one-act dance evolved into a structured , five-act play often based on the tenets of confucian philosophy . before 1868 , when the tokugawa shogunate fell and emperor meiji was restored to power , japan had practiced isolation from other countries , or sakoku . and thus , the development of kabuki had mostly been shaped by domestic influences . but even before this period , european artists , such as claude monet , had become interested in and inspired by japanese art , such as woodblock prints , as well as live performance . after 1868 , others such as vincent van gogh and composer claude debussy began to incorporate kabuki influences in their work , while kabuki itself underwent much change and experimentation to adapt to the new modern era . like other traditional art forms , kabuki suffered in popularity in the wake of world war ii . but innovation by artists such as director tetsuji takechi led to a resurgence shortly after . indeed , kabuki was even considered a popular form of entertainment amongst american troops stationed in japan despite initial u.s. censorship of japanese traditions . today , kabuki still lives on as an integral part of japan 's rich cultural heritage , extending its influence beyond the stage to television , film , and anime . the art form pioneered by okuni continues to delight audiences with the actors ' elaborate makeup , extravagant and delicately embroidered costumes , and the unmistakable melodrama of the stories told on stage .
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due to these influences , the once spontaneous , one-act dance evolved into a structured , five-act play often based on the tenets of confucian philosophy . before 1868 , when the tokugawa shogunate fell and emperor meiji was restored to power , japan had practiced isolation from other countries , or sakoku . and thus , the development of kabuki had mostly been shaped by domestic influences .
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when the tokugawa shogunate fell , what emperor rose to power , and thus , opened japan ’ s ports to the rest of the world ?
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can i hold it ? only if you promise to be really , really careful . i promise i will be so incredibly careful . i will be incredibly careful with it . i promise . so , it 's slippery , be careful . alright , are we ready ? i 'm about to touch a 1kg sphere of silicon-28 atoms . there are about 2.15x10^25 of them . it feels absolutely incredible . wow , that is amazing . besides its creators , i am one of only a handful of people ever to hold this sphere . the raw material used to make it was worth 1 million euros but now that it has been so precisely sculpted -- how much is that worth ? it 's priceless . ... this you are looking at now is the roundest object in the world . how can you say for sure it 's the roundest object ? i mean the earth is pretty round , is n't it ? if this was the earth ... if this were the earth then the highest mountain to the lowest valley would be ... about 14m apart . that is shocking . that is shockingly round . but why would you invest one million euros and thousands of man-hours perfecting a pure , polished silicon sphere ? well the answer is grave . or rather 'grave ' as it would have been pronounced in the original french . you see the grave was the original name for the base unit of mass in the metric system , which became the systeme international d'unites or si units . in 1793 , a commision which included notable scientist and aristocrat antoine lavoisier , defined the base unit of mass as the weight of a cubic decimeter of water at the melting temperature of ice -- essentially just a litre of ice water . the name grave came from the latin gravitas , meaning weight . but it was n't to last . it sounded too similar to the aristocratic title 'graf ' -- which is the equivalent of an earl or a count . and with the french revolution in full swing with the rallying cry of equality for all , you could n't exactly have one unit nobler than the others . at this lavoisier lost his head , literally , not because he helped devise one of the greatest systems of measurement of all time , but because he was collecting taxes as a nobleman . so things really were grave . the new republican government believed a grave would be too big for the things they wanted to measure anyway and and so they settled on the gramme , which was just a thousandth of the grave . but soon they realized that a gram was too small and so they returned to the grave , but since they could n't call it that , they invented the kilogram -- a thousand grams . and that is why out of the seven base si units , the kilogram is the only one to have a prefix in its name . in 1799 the kilogram definition was refined to be the mass of a litre of water at 4 degrees celcius -- the temperature at which it is densest . but water itself is obviously not the most sensible thing to use as a mass standard . so a pure platinum cylinder was created to have the same mass as the water definition and it was declared kilogram of the archives . now it 's important to note at this point the kilogram is no longer tied to the mass of a volume of water -- the kilogram of the archives is by definition the kilogram . 90 years later , in 1889 the kilogram was upgraded to a platinum-iridium alloy cylinder . now it was much harder than the original but was otherwise basically identical . and to this day , it remains the definition of the kilogram . it is officially called the international prototype kilogram , though it 's affectionately known as le grand k -- or big k. oh , and it 's about this big ... it is the only thing in the entire universe with a mass of exactly one kilogram because it is the kilogram . it is also the only si unit that is still defined by a physical object . it sits under three bell jars , next to six sister kilograms , in a climate-controlled vault locked by three independently controlled keys , in the basement of the international bureau of weights and measures on the outskirts of paris . now if you were able to break into the vault and tamper with big k , you would be changing the definition of the kilogram , a definition on which many of our measurements rely , and so you would throw the world into chaos ! well no , not actually -- but how would anyone ever know if the mass of big k changed ? well when it was first created , 40 identical replicas were also made . well they were n't quite identical - they had a mass which was slightly different to big k but those offsets were recorded . now these replicas were sent out to countries around the world to serve as their national standards . in 1948 the kilograms were reunited for a weigh-in . and this is when the problems started . because even though all the cylinders were made of the same alloy and stored under virtually the same conditions , their masses had diverged over time . the mass of big k was n't even the same as the six sister cylinders stored with it . and to make matters worse when they were brought together again forty years later , their masses had further diverged , up to about 50 micrograms - that 's about the weight of a fingerprint . but fingerprints were not the culprits since the kilograms were carefully washed before their weigh-ins . so some physical process must have actually changed the mass of the cylinders , but how that exactly works remains a matter of speculation . one this is for certain , the mass of a platinum-iridium cylinder is not stable over time . and this is a big problem . you ca n't have a unit which changes its value . and the fallout is n't limited to measurements of mass since of the seven base si units , four of them depend on the mass of the kilogram , not to mention all the derived units like newtons , joules , volts and watts . at this point those of you in countries that have not adopted the metric system -- yes i 'm speaking to you liberia , burma , and the us -- you may be feeling rather smug that your unit of mass , the avoirdupois pound , is no longer defined by a physical object . no , instead it is defined as precisely 0.45359237 kilograms . sucked in . so clearly something needs to be done to eliminate the kilogram 's dependence on a physical object and this is where the silicon sphere comes in , but how exactly does that help ? here you have a physical object and it 's beautiful but you know it 's still a physical object . you 're trying to get away from that . we 're trying to get away from the physical object but what we 're doing with this particular object is counting how many atoms are in there . you ca n't actually count how many are in there can you ? you ca n't count how many are in there but you can calculate how many are in there because this material is silicon , there 's no voids or dislocations . so this is like a perfect crystal of silicon . that 's right . not only is it pure silicon , it contains only one isotope of silicon , silicon-28 , and that explains why the original material was so expensive . and why a sphere ? well , a sphere is a pretty simple object . if you know the diameter of the sphere you can characterise the entire dimension of the object . well that explains why the sphere has to be the roundest object ever created , but how do you actually make something that round ? we actually start with an oversized sphere . so it was about two millimetres larger in diameter and then we just grind it progressively finer and finer using abrasive . it 's actually massaging atoms . you 're down at that level of trying to control the shape of an object down at the atomic level . but making the sphere is only half the battle , then you need to accurately measure its diameter . the diameter is actually measured via a laser . so you 're actually measuring having the sphere in the centre of a cavity and a laser is hitting both sides and you 're actually measuring the gap . by knowing the diameter you can determine its volume . and since the atom spacing in silicon is known to high precision , you can the calculate how many atoms make up the sphere . this allows you to redefine avogadro 's constant . at the moment , avogadro 's constant is defined based on the kilogram . it is equal to the number of atoms in twelve grams of carbon 12 . but using this approach , the number of silicon atoms in the sphere would be used to fix avogadro 's constant , which would then define the kilogram . so even if the silicon spheres were lost or damaged , it would have no effect on the definition of the kilogram because it would be defined not by a physical object but by a concept . you would like to see the official definition of the kilogram say `` a kilogram is the mass of 2.15x10^25 silicon-28 atoms '' yes . is it - is it going to happen ? there 's a likelihood , a high likelihood that it 's going to happen . but there is another approach to redefining the kilogram which involves fixing planck 's constant and it 's done using something called a watt balance . these two approaches are complimentary . each one provides a check on the other , and if they show good agreement and are able to bring their uncertainties down to about twenty micrograms they may redefine the kilogram as early as 2014 . and then the kilogram finally will be an unchanging unit , no longer defined by a physical object in the basement vault of some place in paris . now if the kilogram was originally intended to be the mass of a litre of water at its densest temperature then how well did we do ? well if you look at a litre of water at nearly four degrees celcius it has a mass of 999.975 grams . so i guess you could look at this two ways . on the one hand you could say the kilogram is slightly heavier than it should be , but on the other hand 214 years ago , scientists were able to create an artifact that was correct within the margin of error of a grain of rice . now that is truly remarkable . now if you want to hear more about the watt balance , let me know in the comments and i will see what i can do . it does seem to be the frontrunner in terms of redefining the kilogram , so we will have to wait and see what happens . one last thing , i should point out that it took an international collaboration of scientists to create the silicon sphere but do n't you think that the scientist who originally conceived of silicon as an element should receive some of the credit . well in 1787 , that was none other than antoine lavoisier . so he 's been involved in the definition of a kilogram from start to finish or from cradle to grave .
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not only is it pure silicon , it contains only one isotope of silicon , silicon-28 , and that explains why the original material was so expensive . and why a sphere ? well , a sphere is a pretty simple object . if you know the diameter of the sphere you can characterise the entire dimension of the object .
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the avogadro project sphere is an attempt to link the definition of the kilogram to a concept rather than an object ... but the sphere is an object . how does this make sense ?
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astronomers have discovered thousands of planets orbiting stars other than the sun . they come in all sizes , at different orbital distances from their stars . the closest of them are trillions of miles away , and even the largest are just fuzzy patches in the fields of high-powered telescopes . but if one of these planets is close in size to the earth and orbits not too close and too far away from its parent star , it could be rocky and warm enough to have oceans and perhaps life . astronomers discover these potentially habitable planets , and their eyes get big and wide . could one of these distant worlds carry the building blocks of life ? or even a living , breathing , civilization ? is the question , `` are we alone in the universe ? '' about to be answered ? but wait . maybe we should ask a different question first . should we try to find out if we 're alone in the universe ? if we do find the atmospheric fingerprints of life on one of these small , distant worlds , should we try to contact any beings who may live there ? is that wise ? three decades ago , nasa decided the answer was yes . voyager 1 and 2 were launched in 1977 to explore the giant planets in the solar system . each spacecraft carried a golden phonograph record , a time capsule of sorts that included clues and messages meant to convey the story of human civilization . the contents of these gold-plated copper disks were chosen by a committee chaired by american astronomer and author carl sagan . they included over 100 images , and a range of sounds from the natural world : ocean waves , thunder , the sounds of birds and whales . the records also included music from many different time periods and cultures , greetings in 55 languages , and messages from the president of the united states , and the un secretary general . they also included a map . each golden record displays the location of our solar system with respect to fourteen pulsars . their precise , unique frequencies were indicated so that intelligent , extraterrestrial lifeforms could use them to find the earth . many years later , renowned physicist stephen hawking said that it was a mistake to give an alien species a roadmap to our planet . hawking suspected that any extraterrestrial life probably was n't any more complex than microbes , but he warned that if an advanced alien species did visit earth , it could be as catastrophic as christopher columbus 's arrival was for the native americans . meanwhile , the golden records continue their journeys . in 1990 , both voyager spacecraft passed beyond the orbit of pluto . voyager 1 entered interstellar space in 2012 , and will reach the nearest stellar system in 40,000 years . if either spacecraft is discovered by extraterrestrial life , there 's a possibility that they could decipher the clues from the golden record and one day reach our planet . that 's particularly true if theirs is a much more technologically advanced civilization . that life could be benevolent , as we would hope to be if humans are one day able to achieve interstellar travel . or it could be hostile . searching for planets that might have life means staring into a great abyss . we 'll likely have no clear knowledge of the evolutionary stage , sentience , character , or intentions of the first form of life we discover . so it 's a risk to turn our eyes outwards . we risk our very way of life . but it may be a greater risk not to look , to deny the very pioneering spirits that help shape our own species . we are all born curious about the world and the universe . pursuing that curiosity is one of humankind 's greatest achievements . perhaps there is room to push the frontiers of science , provided that we cradle alongside our fervor another of humankind 's greatest assets : hope .
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so it 's a risk to turn our eyes outwards . we risk our very way of life . but it may be a greater risk not to look , to deny the very pioneering spirits that help shape our own species .
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any life we find elsewhere in the universe could look like anything , from the tiniest microbes , all the way to humans , or even more evolved . if there is extraterrestrial life out there that is more evolved than humans , what kind of evolutionary “ improvements ” do you think that life would have made ?
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what do euclid , twelve-year-old einstein , and american president james garfield have in common ? they all came up with elegant proofs for the famous pythagorean theorem , the rule that says for a right triangle , the square of one side plus the square of the other side is equal to the square of the hypotenuse . in other words , a²+b²=c² . this statement is one of the most fundamental rules of geometry , and the basis for practical applications , like constructing stable buildings and triangulating gps coordinates . the theorem is named for pythagoras , a greek philosopher and mathematician in the 6th century b.c. , but it was known more than a thousand years earlier . a babylonian tablet from around 1800 b.c . lists 15 sets of numbers that satisfy the theorem . some historians speculate that ancient egyptian surveyors used one such set of numbers , 3 , 4 , 5 , to make square corners . the theory is that surveyors could stretch a knotted rope with twelve equal segments to form a triangle with sides of length 3 , 4 and 5 . according to the converse of the pythagorean theorem , that has to make a right triangle , and , therefore , a square corner . and the earliest known indian mathematical texts written between 800 and 600 b.c . state that a rope stretched across the diagonal of a square produces a square twice as large as the original one . that relationship can be derived from the pythagorean theorem . but how do we know that the theorem is true for every right triangle on a flat surface , not just the ones these mathematicians and surveyors knew about ? because we can prove it . proofs use existing mathematical rules and logic to demonstrate that a theorem must hold true all the time . one classic proof often attributed to pythagoras himself uses a strategy called proof by rearrangement . take four identical right triangles with side lengths a and b and hypotenuse length c. arrange them so that their hypotenuses form a tilted square . the area of that square is c² . now rearrange the triangles into two rectangles , leaving smaller squares on either side . the areas of those squares are a² and b² . here 's the key . the total area of the figure did n't change , and the areas of the triangles did n't change . so the empty space in one , c² must be equal to the empty space in the other , a² + b² . another proof comes from a fellow greek mathematician euclid and was also stumbled upon almost 2,000 years later by twelve-year-old einstein . this proof divides one right triangle into two others and uses the principle that if the corresponding angles of two triangles are the same , the ratio of their sides is the same , too . so for these three similar triangles , you can write these expressions for their sides . next , rearrange the terms . and finally , add the two equations together and simplify to get ab²+ac²=bc² , or a²+b²=c² . here 's one that uses tessellation , a repeating geometric pattern for a more visual proof . can you see how it works ? pause the video if you 'd like some time to think about it . here 's the answer . the dark gray square is a² and the light gray one is b² . the one outlined in blue is c² . each blue outlined square contains the pieces of exactly one dark and one light gray square , proving the pythagorean theorem again . and if you 'd really like to convince yourself , you could build a turntable with three square boxes of equal depth connected to each other around a right triangle . if you fill the largest square with water and spin the turntable , the water from the large square will perfectly fill the two smaller ones . the pythagorean theorem has more than 350 proofs , and counting , ranging from brilliant to obscure . can you add your own to the mix ?
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state that a rope stretched across the diagonal of a square produces a square twice as large as the original one . that relationship can be derived from the pythagorean theorem . but how do we know that the theorem is true for every right triangle on a flat surface , not just the ones these mathematicians and surveyors knew about ?
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from which culture was the earliest recorded usage of the pythagorean theorem found ?
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your brain on food if you sucked all of the moisture out of your brain and broke it down to its constituent nutritional content , what would it look like ? most of the weight of your dehydrated brain would come from fats , also known as lipids . in the remaining brain matter , you would find proteins and amino acids , traces of micronutrients , and glucose . the brain is , of course , more than just the sum of its nutritional parts , but each component does have a distinct impact on functioning , development , mood , and energy . so that post-lunch apathy , or late-night alertness you might be feeling , well , that could simply be the effects of food on your brain . of the fats in your brain , the superstars are omegas 3 and 6 . these essential fatty acids , which have been linked to preventing degenerative brain conditions , must come from our diets . so eating omega-rich foods , like nuts , seeds , and fatty fish , is crucial to the creation and maintenance of cell membranes . and while omegas are good fats for your brain , long-term consumption of other fats , like trans and saturated fats , may compromise brain health . meanwhile , proteins and amino acids , the building block nutrients of growth and development , manipulate how we feel and behave . amino acids contain the precursors to neurotransmitters , the chemical messengers that carry signals between neurons , affecting things like mood , sleep , attentiveness , and weight . they 're one of the reasons we might feel calm after eating a large plate of pasta , or more alert after a protein-rich meal . the complex combinations of compounds in food can stimulate brain cells to release mood-altering norepinephrine , dopamine , and serotonin . but getting to your brain cells is tricky , and amino acids have to compete for limited access . a diet with a range of foods helps maintain a balanced combination of brain messengers , and keeps your mood from getting skewed in one direction or the other . like the other organs in our bodies , our brains also benefit from a steady supply of micronutrients . antioxidants in fruits and vegetables strengthen the brain to fight off free radicals that destroy brain cells , enabling your brain to work well for a longer period of time . and without powerful micronutrients , like the vitamins b6 , b12 , and folic acid , our brains would be susceptible to brain disease and mental decline . trace amounts of the minerals iron , copper , zinc , and sodium are also fundamental to brain health and early cognitive development . in order for the brain to efficiently transform and synthesize these valuable nutrients , it needs fuel , and lots of it . while the human brain only makes up about 2 % of our body weight , it uses up to 20 % of our energy resources . most of this energy comes from carbohydrates that our body digests into glucose , or blood sugar . the frontal lobes are so sensitive to drops in glucose , in fact , that a change in mental function is one of the primary signals of nutrient deficiency . assuming that we are getting glucose regularly , how does the specific type of carbohydrates we eat affect our brains ? carbs come in three forms : starch , sugar , and fiber . while on most nutrition labels , they are all lumped into one total carb count , the ratio of the sugar and fiber subgroups to the whole amount affect how the body and brain respond . a high glycemic food , like white bread , causes a rapid release of glucose into the blood , and then comes the dip . blood sugar shoots down , and with it , our attention span and mood . on the other hand , oats , grains , and legumes have slower glucose release , enabling a steadier level of attentiveness . for sustained brain power , opting for a varied diet of nutrient-rich foods is critical . when it comes to what you bite , chew , and swallow , your choices have a direct and long-lasting effect on the most powerful organ in your body .
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in order for the brain to efficiently transform and synthesize these valuable nutrients , it needs fuel , and lots of it . while the human brain only makes up about 2 % of our body weight , it uses up to 20 % of our energy resources . most of this energy comes from carbohydrates that our body digests into glucose , or blood sugar . the frontal lobes are so sensitive to drops in glucose , in fact , that a change in mental function is one of the primary signals of nutrient deficiency .
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most of the energy that your brain uses comes from :
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how many times does the chorus repeat in your favorite song ? and , take a moment to think , how many times have you listened to it ? chances are you 've heard that chorus repeated dozens , if not hundreds , of times , and it 's not just popular songs in the west that repeat a lot . repetition is a feature that music from cultures around the world tends to share . so , why does music rely so heavily on repetition ? one part of the answer come from what psychologists call the mere-exposure effect . in short , people tend to prefer things they 've been exposed to before . for example , a song comes on the radio that we do n't particularly like , but then we hear the song at the grocery store , at the movie theater and again on the street corner . soon , we are tapping to the beat , singing the words , even downloading the track . this mere-exposure effect does n't just work for songs . it also works for everything from shapes to super bowl ads . so , what makes repetition so uniquely prevalent in music ? to investigate , psychologists asked people to listen to musical compositions that avoided exact repetition . they heard excerpts from these pieces in either their original form , or in a version that had been digitally altered to include repetition . although the original versions had been composed by some of the most respected 20th century composers , and the repetitive versions had been assembled by brute force audio editing , people rated the repetitive versions as more enjoyable , more interesting and more likely to have been composed by a human artist . musical repetition is deeply compelling . think about the muppets classic , `` mahna mahna . '' if you 've heard it before , it 's almost impossible after i sing , `` mahna mahna , '' not to respond , `` do doo do do do . '' repetition connects each bit of music irresistibly to the next bit of music that follows it . so when you hear a few notes , you 're already imagining what 's coming next . your mind is unconsciously singing along , and without noticing , you might start humming out loud . recent studies have shown that when people hear a segment of music repeated , they are more likely to move or tap along to it . repetition invites us into music as imagined participants , rather than as passive listeners . research has also shown that listeners shift their attention across musical repetitions , focusing on different aspects of the sound on each new listen . you might notice the melody of a phrase the first time , but when it 's repeated , your attention shifts to how the guitarist bends a pitch . this also occurs in language , with something called semantic satiation . repeating a word like atlas ad nauseam can make you stop thinking about what the word means , and instead focus on the sounds : the odd way the `` l '' follows the `` t. '' in this way , repetition can open up new worlds of sound not accessible on first hearing . the `` l '' following the `` t '' might not be aesthetically relevant to `` atlas , '' but the guitarist pitch bending might be of critical expressive importance . the speech to song illusion captures how simply repeating a sentence a number of times shifts listeners attention to the pitch and temporal aspects of the sound , so that the repeated spoken language actually begins to sound like it is being sung . a similar effect happens with random sequences of sound . people will rate random sequences they 've heard on repeated loop as more musical than a random sequence they 've only heard once . repetition gives rise to a kind of orientation to sound that we think of as distinctively musical , where we 're listening along with the sound , engaging imaginatively with the note about to happen . this mode of listening ties in with our susceptibility to musical ear worms , where segments of music burrow into our head , and play again and again , as if stuck on repeat . critics are often embarrassed by music 's repetitiveness , finding it childish or regressive , but repetition , far from an embarrassment , is actually a key feature that gives rise to the kind of experience we think about as musical .
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and , take a moment to think , how many times have you listened to it ? chances are you 've heard that chorus repeated dozens , if not hundreds , of times , and it 's not just popular songs in the west that repeat a lot . repetition is a feature that music from cultures around the world tends to share .
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after you 've head a piece repeated a lot :
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so comrades , welcome to the lecture . what i am going to do now , we ’ re going to begin with an experiment to illustrate this point that the oxygen molecule , o2 , has unpaired electrons . now we ’ re outside just to show you the reactivity of this lovely stuff here , liquid oxygen . so you can see wonderful liquid oxygen is a nice blue colour . so over here on the table we ’ ve got a tin tray which we ’ re going to use to contain the experiment that i ’ m going to show you next . so we ’ ve got our favourite liquid oxygen . strongly oxidising ; very , very reactive , and here i ’ ve got some cotton wool . so this is the same stuff we use to take make-up off , perhaps our partners or our girlfriends or our wives , and this is the same stuff we use to wipe our babies ’ bums . oxygen is an interesting element because it exists in two forms : the taught form which we breathe all the time is o2 , two oxygen atoms joined together ; and there ’ s another form called ozone , and which has three atoms arranged like the letter v , or letter v this way up . oxygen has unpaired electrons within the molecular orbitals , in the atomic orbitals around the structure , and these unpaired electrons give rise to colour and that colour is blue . so blue is often perceived to be the colour of solvated or unpaired electrons , and you can see here the lovely blue colour . now lots of chemists are really scared when they see the blue of liquid oxygen , because liquid oxygen is very , very reactive . generally you only make liquid oxygen by mistake . not like today when we ’ re making some on purpose . and if you ’ ve made it by mistake in an uncontrolled way , where there might be organic molecules perhaps simple organic chemicals like hydrocarbons , grease or perhaps a highly elaborate compound then , they tend to detonate and they tend to cause very energetic experiments . yeah it ’ s very fluffy it ’ s not very reactive . it doesn ’ t really burn , it cinders , might smoulder . but here we go , we ’ re going to pop it in the tray . so we begin with neil ’ s very high-tech piece of equipment , which is a test-tube on a piece of string . what we ’ re going to do is to put some liquid nitrogen in here . you can see liquid nitrogen – well you may not see – is colourless . ok ? so this is liquid nitrogen , and what i hope you can see is that this magnet , which is a pretty good magnet . let me just show you here with my keys , that they stick pretty strongly to the magnet . the magnet has absolutely no affect at all on the liquid nitrogen . i can pull the magnet and nothing happens . and then we ’ re going to fill up all of the void space , so all of the space in the cotton particles with oxygen . so you might want to stand back after this bit brady . so here we go , here ’ s our liquid oxygen . do you want to come in and zoom in on me ? it ’ s ok , i ’ ve got it zoomed nicely . ok , so here you can see the lovely blue liquid oxygen colour , going into the cotton wool particles . let ’ s try the same thing with liquid oxygen . careful of my shoes… so here we have a match on a stick , and i think you can see its probably alight , so we have our fire , we have our oxygen , and we have our fuel . now let ’ s see what happens when we put them all together . the liquid oxygen is a very nice blue colour today . so now let ’ s try , here ’ s the magnet again , and if i take the liquid oxygen you can see i can pull it right up here . it ’ s not as magnetic as my keys , but you can see there ’ s a really big difference . it sticks to the magnet . so you can see it really is magnetic . you ready ? ok. woohoo and there she blows ! and ozone is much more reactive than oxygen . so near the earth ’ s surface , where you and i are at the moment , ozone is really quite dangerous because if you breathe it in it can start reacting with any sort of molecule that has bonds between carbon . but in the upper atmosphere , ozone is extremely important because it absorbs ultra-violet light that comes from the sun and stops this ultra-violet light attacking the molecules in biological species on the surface . if it wasn ’ t for the ozone in the upper atmosphere all of us would be , if not dead , certainly very much less comfortable than we are at the moment . so neil ’ s now connecting up a piece of tube to oxygen cylinder and he is going to fill up this gas jar with oxygen and we are going to do a really classic experiment : the one that everyone learns at school and tests for oxygen , which is to relight a glowing splint . so we have a traditional gas jar full of oxygen . so here you can see we are burning a splint . ok , so this is the wood burning in excess oxygen around us , ok . so what we are going to do is we are going to take the splint out so it is just glowing . and if i blow on this splint you can see it gets brighter . now we are going to try and relight that splint by putting it into a very oxygen-rich atmosphere . so we ’ ll move over to the jar and we ’ ll put in our glowing splint and you can see the flame comes back to life . so that ’ s a test that everyone learns for an oxygen-rich environment . what happened ? what made that happen ? well the increased oxygen content/concentration reignites and reinitiates that oxidation of the wood or the burning of the wood . so we ’ ll do that again . so there we go : flame again .
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so blue is often perceived to be the colour of solvated or unpaired electrons , and you can see here the lovely blue colour . now lots of chemists are really scared when they see the blue of liquid oxygen , because liquid oxygen is very , very reactive . generally you only make liquid oxygen by mistake .
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we need oxygen to live . when we breathe , the oxygen , contained within the air , is distributed throughout our bodies by our arteries . oxygen is carried by red blood cells . these red blood cells are linked to a metalloprotein , which have an iron atom in its middle . what is the name of this molecule ?
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one day , i found myself at the top of a mountain , one descent to go , one last chance to fulfill a lifelong dream . i was n't even old enough to walk into a pg-13 movie alone when my dream took roots . yet there i stood , my three teammates by my side , facing the opportunity to make history . my mind wandered , just for half a second , but that half-second was filled with a lifetime of memories , and two decisions that brought me here to the top of the mountain . i made the first decision after a very challenging period in my career as an athlete -- five years of recurring injuries as a track athlete . five years -- that 's a long time to dedicate to anything . but as much as i loved track , the injuries were slowly killing my drive and my dreams . my injuries had me feeling like a failure at a sport i was once great at . the last of the series of injuries required major elbow surgery . as i sat on my couch , days out of surgery , i thought of an old coach and mentor 's words , comparing me to a great bobsledder he once knew . `` bobsled ? no way ! '' but after year upon year of not reaching the goals i set for myself in track , it was time for a change . so i reached out to the us olympic committee , and they told me to start training . i was going to be a bobsledder ! i did n't know anything about it , but the first decision had been made . there i was , in what felt like a blink of an eye later , about to push my four-man sled with my team to the chance of olympic gold , olympic glory . `` back set ! front set ! ready and -- '' the driver yelled , and off we went . we dug as deep as we could , and as the cadence of our steps increased and the sled accelerated , we left everything we had on the track , before leaving the ice and boarding our night train sled . and a calm came over me . and once in the sled , as it was picking up speed , for just another millisecond , my mind went back to that day on the couch . `` how can i train for the bobsled team without getting hurt over and over again like before ? '' i looked in the mirror and realized i still wanted to compete . i still wanted to succeed . but i had to face the reality that my getting hurt was n't to be blamed elsewhere . i realized that if i had a problem it was up to me to change it , and that what i had been doing all this time may not have been best for me . i had to confront my reality and make a change , and that was the second decision . the decision in my mind not to get hurt anymore had many layers , but it mostly had to do with taking responsibility for all the variables in my life . if i thought something i would do or something i felt would lead me to injury , then it most certainly would . i would have to have a fundamental shift in mindset . i learned to let go of the fears i had trained myself to have over the years and decided to trust myself and my body to push through situations i had thought insurmountable before . what followed those five years of injuries were nine years of not missing one race i entered for the usa national and olympic teams . because i made a decision , then another one , and held true to those two decisions , i found myself back with my team approaching 90 miles per hour . and as we came around the last corners , i could hear the crowd cheering and the cowbells blaring , and a hard `` you ! '' coming from the masses as we passed by at 95 miles an hour . but someone was n't yelling `` you ! '' at us , they were yelling `` usa ! '' we were moving so fast , we only heard the first piece of it . we then came around the last bend , and when we all looked up , the clock simply read `` 1 . '' we had done it ; we were olympic gold medalists . we were the best in the world . my hands went up immediately , as the moment i had been waiting for my entire life had finally come true . and as our sled slowly came to a stop and i looked into the crowd to see my mom , dad , sister and family and friends crying for me , i knew my decisions had been worth the sacrifice , worth the fear . two decisions and those five minutes sitting on that couch began to change my life , and sticking to them fulfilled my dreams . it was those decisions and standing by them that ultimately gave me the confidence to perform at the olympic games . what two decisions can you make and stick to that will change your life forever ? i challenge you to look at what you 're doing in your life and think of what you dream to do .
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my mind wandered , just for half a second , but that half-second was filled with a lifetime of memories , and two decisions that brought me here to the top of the mountain . i made the first decision after a very challenging period in my career as an athlete -- five years of recurring injuries as a track athlete . five years -- that 's a long time to dedicate to anything .
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how many years did mesler incur injuries as a track athlete ?
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have you experienced déjà vu ? it 's that shadowy feeling you get when a situation seems familiar . a scene in a restaurant plays out exactly as you remember . the world moves like a ballet you 've choreographed , but the sequence ca n't be based on a past experience because you 've never eaten here before . this is the first time you 've had clams , so what 's going on ? unfortunately , there is n't one single explanation for déjà vu . the experience is brief and occurs without notice , making it nearly impossible for scientists to record and study it . scientists ca n't simply sit around and wait for it to happen to them -- this could take years . it has no physical manifestations and in studies , it 's described by the subject as a sensation or feeling . because of this lack of hard evidence , there 's been a surplus of speculation over the years . since emile boirac introduced déjà vu as a french term meaning `` already seen , '' more than 40 theories attempt to explain this phenomenon . still , recent advancements in neuroimaging and cognitive psychology narrow down the field of prospects . let 's walk through three of today 's more prevalent theories , using the same restaurant setting for each . first up is dual processing . we 'll need an action . let 's go with a waiter dropping a tray of dishes . as the scene unfolds , your brain 's hemispheres process a flurry of information : the waiter 's flailing arms , his cry for help , the smell of pasta . within milliseconds , this information zips through pathways and is processed into a single moment . most of the time , everything is recorded in-sync . however , this theory asserts that déjà vu occurs when there 's a slight delay in information from one of these pathways . the difference in arrival times causes the brain to interpret the late information as a separate event . when it plays over the already-recorded moment , it feels as if it 's happened before because , in a sense , it has . our next theory deals with a confusion of the past rather than a mistake in the present . this is the hologram theory , and we 'll use that tablecloth to examine it . as you scan its squares , a distant memory swims up from deep within your brain . according to the theory , this is because memories are stored in the form of holograms , and in holograms , you only need one fragment to see the whole picture . your brain has identified the tablecloth with one from the past , maybe from your grandmother 's house . however , instead of remembering that you 've seen it at your grandmother 's , your brain has summoned up the old memory without identifying it . this leaves you stuck with familiarity , but no recollection . although you 've never been in this restaurant , you 've seen that tablecloth but are just failing to identify it . now , look at this fork . are you paying attention ? our last theory is divided attention , and it states that déjà vu occurs when our brain subliminally takes in an environment while we 're distracted by one particular object . when our attention returns , we feel as if we 've been here before . for example , just now you focused on the fork and did n't observe the tablecloth or the falling waiter . although your brain has been recording everything in your peripheral vision , it 's been doing so below conscious awareness . when you finally pull yourself away from the fork , you think you 've been here before because you have , you just were n't paying attention . while all three of these theories share the common features of déjà vu , none of them propose to be the conclusive source of the phenomenon . still , while we wait for researchers and inventers to come up with new ways to capture this fleeting moment , we can study the moment ourselves . after all , most studies of déjà vu are based on first-hand accounts , so why ca n't one be yours ? the next time you get déjà vu , take a moment to think about it . have you been distracted ? is there a familiar object somewhere ? is your brain just acting slow ? or is it something else ?
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while all three of these theories share the common features of déjà vu , none of them propose to be the conclusive source of the phenomenon . still , while we wait for researchers and inventers to come up with new ways to capture this fleeting moment , we can study the moment ourselves . after all , most studies of déjà vu are based on first-hand accounts , so why ca n't one be yours ?
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how can a fragment of memory summon up a moment from the past ?
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translator : elena montrasio reviewer : ted translators admin [ his holiness pope francis filmed in vatican city first shown at ted2017 ] good evening – or , good morning , i am not sure what time it is there . regardless of the hour , i am thrilled to be participating in your conference . i very much like its title – `` the future you '' – because , while looking at tomorrow , it invites us to open a dialogue today , to look at the future through a `` you . '' `` the future you : '' the future is made of yous , it is made of encounters , because life flows through our relations with others . quite a few years of life have strengthened my conviction that each and everyone 's existence is deeply tied to that of others : life is not time merely passing by , life is about interactions . as i meet , or lend an ear to those who are sick , to the migrants who face terrible hardships in search of a brighter future , to prison inmates who carry a hell of pain inside their hearts , and to those , many of them young , who can not find a job , i often find myself wondering : `` why them and not me ? '' i , myself , was born in a family of migrants ; my father , my grandparents , like many other italians , left for argentina and met the fate of those who are left with nothing . i could have very well ended up among today 's `` discarded '' people . and that 's why i always ask myself , deep in my heart : `` why them and not me ? '' first and foremost , i would love it if this meeting could help to remind us that we all need each other , none of us is an island , an autonomous and independent `` i , '' separated from the other , and we can only build the future by standing together , including everyone . we don ’ t think about it often , but everything is connected , and we need to restore our connections to a healthy state . even the harsh judgment i hold in my heart against my brother or my sister , the open wound that was never cured , the offense that was never forgiven , the rancor that is only going to hurt me , are all instances of a fight that i carry within me , a flare deep in my heart that needs to be extinguished before it goes up in flames , leaving only ashes behind . many of us , nowadays , seem to believe that a happy future is something impossible to achieve . while such concerns must be taken very seriously , they are not invincible . they can be overcome when we do n't lock our door to the outside world . happiness can only be discovered as a gift of harmony between the whole and each single component . even science – and you know it better than i do – points to an understanding of reality as a place where every element connects and interacts with everything else . and this brings me to my second message . how wonderful would it be if the growth of scientific and technological innovation would come along with more equality and social inclusion . how wonderful would it be , while we discover faraway planets , to rediscover the needs of the brothers and sisters orbiting around us . how wonderful would it be if solidarity , this beautiful and , at times , inconvenient word , were not simply reduced to social work , and became , instead , the default attitude in political , economic and scientific choices , as well as in the relationships among individuals , peoples and countries . only by educating people to a true solidarity will we be able to overcome the `` culture of waste , '' which does n't concern only food and goods but , first and foremost , the people who are cast aside by our techno-economic systems which , without even realizing it , are now putting products at their core , instead of people . solidarity is a term that many wish to erase from the dictionary . solidarity , however , is not an automatic mechanism . it can not be programmed or controlled . it is a free response born from the heart of each and everyone . yes , a free response ! when one realizes that life , even in the middle of so many contradictions , is a gift , that love is the source and the meaning of life , how can they withhold their urge to do good to another fellow being ? in order to do good , we need memory , we need courage and we need creativity . and i know that ted gathers many creative minds . yes , love does require a creative , concrete and ingenious attitude . good intentions and conventional formulas , so often used to appease our conscience , are not enough . let us help each other , all together , to remember that the other is not a statistic or a number . the other has a face . the `` you '' is always a real presence , a person to take care of . there is a parable jesus told to help us understand the difference between those who 'd rather not be bothered and those who take care of the other . i am sure you have heard it before . it is the parable of the good samaritan . when jesus was asked : `` who is my neighbor ? '' - namely , `` who should i take care of ? '' - he told this story , the story of a man who had been assaulted , robbed , beaten and abandoned along a dirt road . upon seeing him , a priest and a levite , two very influential people of the time , walked past him without stopping to help . after a while , a samaritan , a very much despised ethnicity at the time , walked by . seeing the injured man lying on the ground , he did not ignore him as if he were n't even there . instead , he felt compassion for this man , which compelled him to act in a very concrete manner . he poured oil and wine on the wounds of the helpless man , brought him to a hostel and paid out of his pocket for him to be assisted . the story of the good samaritan is the story of today ’ s humanity . people 's paths are riddled with suffering , as everything is centered around money , and things , instead of people . and often there is this habit , by people who call themselves `` respectable , '' of not taking care of the others , thus leaving behind thousands of human beings , or entire populations , on the side of the road . fortunately , there are also those who are creating a new world by taking care of the other , even out of their own pockets . mother teresa actually said : `` one can not love , unless it is at their own expense . '' we have so much to do , and we must do it together . but how can we do that with all the evil we breathe every day ? thank god , no system can nullify our desire to open up to the good , to compassion and to our capacity to react against evil , all of which stem from deep within our hearts . now you might tell me , `` sure , these are beautiful words , but i am not the good samaritan , nor mother teresa of calcutta . '' on the contrary : we are precious , each and every one of us . each and every one of us is irreplaceable in the eyes of god . through the darkness of today 's conflicts , each and every one of us can become a bright candle , a reminder that light will overcome darkness , and never the other way around . to christians , the future does have a name , and its name is hope . feeling hopeful does not mean to be optimistically naïve and ignore the tragedy humanity is facing . hope is the virtue of a heart that does n't lock itself into darkness , that does n't dwell on the past , does not simply get by in the present , but is able to see a tomorrow . hope is the door that opens onto the future . hope is a humble , hidden seed of life that , with time , will develop into a large tree . it is like some invisible yeast that allows the whole dough to grow , that brings flavor to all aspects of life . and it can do so much , because a tiny flicker of light that feeds on hope is enough to shatter the shield of darkness . a single individual is enough for hope to exist , and that individual can be you . and then there will be another `` you , '' and another `` you , '' and it turns into an `` us . '' and so , does hope begin when we have an `` us ? '' no . hope began with one `` you . '' when there is an `` us , '' there begins a revolution . the third message i would like to share today is , indeed , about revolution : the revolution of tenderness . and what is tenderness ? it is the love that comes close and becomes real . it is a movement that starts from our heart and reaches the eyes , the ears and the hands . tenderness means to use our eyes to see the other , our ears to hear the other , to listen to the children , the poor , those who are afraid of the future . to listen also to the silent cry of our common home , of our sick and polluted earth . tenderness means to use our hands and our heart to comfort the other , to take care of those in need . tenderness is the language of the young children , of those who need the other . a child ’ s love for mom and dad grows through their touch , their gaze , their voice , their tenderness . i like when i hear parents talk to their babies , adapting to the little child , sharing the same level of communication . this is tenderness : being on the same level as the other . god himself descended into jesus to be on our level . this is the same path the good samaritan took . this is the path that jesus himself took . he lowered himself , he lived his entire human existence practicing the real , concrete language of love . yes , tenderness is the path of choice for the strongest , most courageous men and women . tenderness is not weakness ; it is fortitude . it is the path of solidarity , the path of humility . please , allow me to say it loud and clear : the more powerful you are , the more your actions will have an impact on people , the more responsible you are to act humbly . if you don ’ t , your power will ruin you , and you will ruin the other . there is a saying in argentina : `` power is like drinking gin on an empty stomach . '' you feel dizzy , you get drunk , you lose your balance , and you will end up hurting yourself and those around you , if you don ’ t connect your power with humility and tenderness . through humility and concrete love , on the other hand , power – the highest , the strongest one – becomes a service , a force for good . the future of humankind is n't exclusively in the hands of politicians , of great leaders , of big companies . yes , they do hold an enormous responsibility . but the future is , most of all , in the hands of those people who recognize the other as a `` you '' and themselves as part of an `` us . '' we all need each other . and so , please , think of me as well with tenderness , so that i can fulfill the task i have been given for the good of the other , of each and every one , of all of you , of all of us . thank you .
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when one realizes that life , even in the middle of so many contradictions , is a gift , that love is the source and the meaning of life , how can they withhold their urge to do good to another fellow being ? in order to do good , we need memory , we need courage and we need creativity . and i know that ted gathers many creative minds .
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why does people francis believe we all need each other ?
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if you visit a museum with a collection of modern and contemporary art , you 're likely to see works that sometimes elicit the response , `` my cat could make that , so how is it art ? '' a movement called abstract expressionism , also known as the new york school , gets this reaction particularly often . abstract expressionism started in 1943 and developed after the end of world war ii . it 's characterized by large , primarily abstract paintings , all-over compositions without clear focal points , and sweeping swaths of paint embodying and eliciting emotions . the group of artists who are considered abstract expressionists includes barnett newman with his existential zips , willem de kooning , famous for his travestied women , helen frankenthaler , who created soak-stains , and others . but perhaps the most famous , influential , and head-scratching one was jackson pollock . most of his paintings are immediately recognizable . they feature tangled messes of lines of paint bouncing around in every direction on the canvas . and sure , these fields of chaos are big and impressive , but what 's so great about them ? did n't he just drip the paint at random ? ca n't anyone do that ? well , the answer to these questions is both yes and no . while pollock implemented a technique anyone is technically capable of regardless of artistic training , only he could have made his paintings . this paradox relates to his work 's roots in the surrealist automatic drawings of andré masson and others . these surrealists supposedly drew directly from the unconscious to reveal truths hidden within their minds . occasionally , instead of picturing something and then drawing it , they let their hands move automatically and would later tease out familiar figures that appeared in the scribbles . and after pollock moved away from representation , he made drip , or action , paintings following a similar premise , though he developed a signature technique and never looked for images or messages hidden in the works . first , he took the canvas off of the easel and laid it on the floor , a subversive act in itself . then , in a controlled dance , he stepped all around the canvas , dripping industrial paint onto it from stirrers and other tools , changing speed and direction to control how the paint made contact with the surface . these movements , like the surrealist scribbles , were supposedly born out of pollock 's subconscious . but unlike the surrealists , whose pictures represented the mind 's hidden contents , pollock 's supposedly made physical manifestations of his psyche . his paintings are themselves signatures of his mind . in theory , anyone could make a painting that is an imprint of their mind . so why is pollock so special ? well , it 's important to remember that while anyone could have done what he did , he and the rest of the new york school were the ones who actually did it . they destroyed conventions of painting that had stood for centuries , forcing the art world to rethink them entirely . but one last reason why jackson pollock 's work has stayed prominent stems from the specific objects he made , which embody fascinating contradictions . for instance , while pollock 's process resulted in radically flat painted surfaces , the web of painted lines can create the illusion of an infinite layered depth when examined up close . and the chaos of this tangled mess seems to defy all control , but it 's actually the product of a deliberate , though not pre-planned , process . these characteristics made pollock into a celebrity , and within art history , they also elevated him to the mythified status of the genius artist as hero . so rather than evening the playing field for all creative minds , his work unfortunately reinforced a long-standing elitist aspect of art . elitist , innovative , whatever you choose to call it , the history embedded in abstract expressionism is one that no cat , however talented , can claim .
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well , it 's important to remember that while anyone could have done what he did , he and the rest of the new york school were the ones who actually did it . they destroyed conventions of painting that had stood for centuries , forcing the art world to rethink them entirely . but one last reason why jackson pollock 's work has stayed prominent stems from the specific objects he made , which embody fascinating contradictions .
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what are some of the “ conventions of painting ” that stood for centuries that the new york school artists challenged ?
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in 1997 , jk rowling published harry potter and the philosopher 's stone . but most of her audience didn ’ t actually read that book . they read harry potter and the sorcerer ’ s stone . or harry potter a l'ecole des sorciers harry potter va sang-e jadu harry potter y la piedra filosofal [ cool humming of `` hedwig 's theme '' ] the bewitching harry potter books have reached readers in over 200 territories in over 60 languages . the authorized translations came from separate publishing houses with little oversight from the author . so translators were not only tasked with adapting the text from english into their target languages and cultures , but also making assumptions about rowling ’ s intentions and translating the spirit of her approach . their task was particularly challenging because the harry potter series is filled with invented words , alliteration , wordplay , and british cultural references . the main characters first names : harry , hermione , and ron mostly stayed the same across languages , with small changes to accommodate different alphabets and phonetics . that ’ s easy enough for conventional names like harry potter . but many of the other proper names in the book carry loaded meanings — meanings that would be lost if it ’ s not translated . take severus snape . the name invokes severity and sounds like “ snake. ” so the italian translator made the jump and named him severus piton —which is basically python . in french , he ’ s severus rogue which means severus `` arrogance '' . as you can tell , both solutions sacrificed rowling ’ s alliteration . the name “ hogwarts ” combines two english words , but because the name stayed the same in most languages , those connotations were lost for those readers . in an attempt to preserve rowling ’ s approach to the school ’ s name , the french translator used “ poudlard. ” `` pou du lard '' means lice of bacon or fat . the hungarian version went with “ roxfort ” a mix of the british university oxford and roquefort—a well known blue cheese . the house names and founders , also experienced unique adaptations in some of the target languages . in catalan the names became : nícanor griffindor , sírpentin slytherin , mari pau ravenclaw , and horténsia hufflepuff . there ’ s a ton of word play that happens in the harry potter books as well . the famous diagon alley , a play on the word `` diagonally '' and the infamous knockturn alley from `` nocturnally '' . this type of pun is a real puzzle for translators , and most dropped it in favor of literal translations . the spanish translator was able to rhyme at least with “ callejón diagon. ” and translators had several approaches to quidditch , an invented game made from the invented words quaffle , bludger , and snitch— the 3 types of balls used in the game . in spanish , the words were not changed . the french translator kept the word quidditch but changed the names of the balls . and others changed the game ’ s name altogether . in dutch , quidditch is “ zwerkbal. ” in norwegian , it ’ s “ rumpeldunk . '' owls and newts , standardized tests in the wizarding world , weren ’ t always able to retain their animal acronyms . but in swedish their implied meanings remained while the wording was changed . owls became grund examen i trollkonst or g.e.t meaning goat in swedish . and newts were changed to fruktansvärt utmattande trollkarls test or f.u.t.t . derived from `` futtig '' meaning measly or mean . the infamous anagram of tom marvolo riddle ’ s name was altered by many translators to achieve the same revelation of “ i am lord voldemort. ” in danish , tom is named `` romeo g. detlev jr. '' and in french he is “ tom elvis jedusor ” which was extra clever because `` jeu du sort '' means “ fate riddle. ” culturally , the harry potter series is unmistakably british but translating that for a global group of readers wasn ’ t easy . some food items were changed to make them less foreign for the target country . sherbet lemons , a popular candy item in britain , became krembo , a chocolate covered sweet from israel . crisps became chips in the us and in the arabic version , bacon became eggs . sometimes a foreign setting undergoes translation too . for the ukrainian translation , the atmosphere of an english boarding school was swapped out for an orphanage . in the books and films , hagrid has a provincial west country accent . hagrid : `` no ? blimey harry , did n't you ever wonder where your mum and dad learned it all ? '' `` you 're a wizard , harry . '' for the japanese translations , it was replicated by using tōhoku dialect , which is a pastoral accent from northeastern japan . other translators chose to have hagrid simply speak more informally , while others dropped his accent entirely . despite translators ’ best efforts to remain true to the text some things still were lost in translation . in the mainland chinese editions of harry potter there were footnotes to explain puns and cultural references . the spanish translator sometimes used italics to signal an invented word with no translation . but in the end , it doesn ’ t matter if you ’ re reading harry potter and philosopher ’ s stone or the many translations of it . one thing that always seems to translate is the love fans around the world share for tales of `` the boy who lived . ''
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in catalan the names became : nícanor griffindor , sírpentin slytherin , mari pau ravenclaw , and horténsia hufflepuff . there ’ s a ton of word play that happens in the harry potter books as well . the famous diagon alley , a play on the word `` diagonally '' and the infamous knockturn alley from `` nocturnally '' .
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list three characters from the harry potter series whose names might be difficult to translate because of their alliteration , word play , definition or connotation .
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would n't it be great if we could be invisible ? ha , right ? i mean , we could spy on people without being noticed and do whatever we want without being held responsible . now , magicians have figured out how to utilize full-sized mirrors to bend light in order to create disappearing illusions . scientists have created metamaterials to guide rays of light around tiny , two-dimensional objects . cameras can also film what is behind you and project the image so you appear invisible from the front . however , none of these options can make an object as large as a person appear invisible for all angles and distances while its moving . but if you are truly invisible , as in from within , here are a few problems you may not have thought about before . to move around undetected by other people , you would have to be totally naked . even if it 's freezing outside ! you ca n't carry anything , including your wallet and keys , otherwise people would just see your wallet and keys floating around . drivers and people on the street ca n't see you either , therefore they can and will run into you at some point . oh , and you better not wear any perfume or make any noise breathing , otherwise they 'll know you 're there . and , just because you start off invisible , does n't mean you 'll stay that way . what if someone accidentally spills scolding hot coffee on you ? and what if it rains ? but if you think only liquid can make you visible , you 're wrong . dust consists of dead skin cells from humans , soil particles , and fibers from clothes made from cotton and other materials . dust sticks to the moisture on our skin when we sweat and the tiny hairs on our skin when we are dry . so , even if you are invisible , dust would still land on every part of you . we usually do n't notice the dust on our skin because we ca n't see a thin layer of dust on top of our skin color . but , if you 're invisible , people would see a human-shaped blob of dust walking around with extremely dirty soles . gross ! what do you think the world looks like if you are invisible ? well , the answer is nothing . the reason you ca n't see in the dark is because there is no light . to see an apple , light has to hit the apple and return it to your eyes . then , the retinas in your eyes catch the light reflection for your brain to interpret into the image of an apple . if you 're invisible , then , by definition , light would travel through you or around you instead of bouncing off you for people to see . but that means that retinas in your eyes are not catching the light , either . therefore , your brain has nothing to interpret into an image . can you see your reflection without a mirror to stop the light ? no . so , when you ca n't be seen by others , you also can not see . ouch ! now , have you given any thought as of whether the invisibility is permanent ? if it is , how can you receive medical treatment from a doctor if you 're injured ? the doctor would n't know where to apply ointments or bandages because they can not access your injury . for that matter , you ca n't see it either . i mean , what if you have an illness or an infection ? how can the doctor diagnose you without being able to see the color change or inflammation ? and what if everyone is permanently invisible ? well , think about how boring the world would be without seeing people on the streets , on tv , or at home on your computer like right now . it 's lonely being invisible . now , which superpower physics lesson will you explore next ? shifting body size and content , super speed , flight , super strength , immortality , and invisibility .
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cameras can also film what is behind you and project the image so you appear invisible from the front . however , none of these options can make an object as large as a person appear invisible for all angles and distances while its moving . but if you are truly invisible , as in from within , here are a few problems you may not have thought about before .
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what are some of the things that can make an invisible person visible again in other people ’ s eyes ?
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on october 4 , 1957 , the world watched in awe and fear as the soviet union launched sputnik , the world 's first man-made satellite , into space . this little metal ball , smaller than two feet in diameter , launched a space race between the u.s. and u.s.s.r. that would last for eighteen years and change the world as we know it . sputnik was actually not the first piece of human technology to enter space . that superlative goes to the v-2 rocket used by germany in missile attacks against allied cities as a last-ditch effort in the final years of world war ii . it was n't very effective , but , at the end of the war , both the u.s. and u.s.s.r. had captured the technology and the scientists that had developed it and began using them for their own projects . and by august 1957 , the soviet 's successfully tested the first intercontinental ballistic missile , the r-7 , the same rocket that would be used to launch sputnik two months later . so , the scary thing about sputnik was not the orbiting ball itself , but the fact that the same technology could be used to launch a nuclear warhead at any city . not wanting to fall too far behind , president eisenhower ordered the navy to speed up its own project and launch a satellite as soon as possible . so , on december 6 , 1957 , excited people across the nation tuned in to watch the live broadcast as the vanguard tv3 satellite took off and crashed to the ground two seconds later . the vanguard failure was a huge embarassment for the united states . newspapers printed headlines like , `` flopnik '' and `` kaputnik . '' and a soviet delegate at the u.n. mockingly suggested that the u.s. should receive foreign aid for developing nations . fortunately , the army had been working on their own parallel project , the explorer , which was successfully launched in january 1958 , but the u.s. had barely managed to catch up before they were surpassed again as yuri gargarin became the first man in space in april 1961 . almost a year passed and several more soviet astronauts completed their missions before project mercury succeeded in making john glenn the first american in orbit in february 1962 . by this time , president kennedy had realized that simply catching up to each soviet advance a few months later was n't going to cut it . the u.s. had to do something first , and in may 1961 , a month after gargarin 's flight , he announced the goal of putting a man on the moon by the end of the 1960s . they succeeded in this through the apollo program with neil armstrong taking his famous step on july 20 , 1969 . with both countries ' next turning their attention to orbital space stations , there 's no telling how much longer the space race could have gone on . but because of improving relations negotiated by soviet premier leonid breshnev and u.s. president nixon , the u.s.s.r. and u.s. moved toward cooperation rather than competition . the successful joint mission , known as apollo-soyuz , in which an american apollo spacecraft docked with a soviet soyuz craft and the two crews met , shook hands , and exchanged gifts , marked the end of the space race in 1975 . so , in the end , what was the point of this whole space race ? was it just a massive waste of time ? two major superpowers trying to outdo each other by pursuing symbolic projects that were both dangerous and expensive , using resources that could have been better spent elsewhere ? well , sure , sort of , but the biggest benefits of the space program had nothing to do with one country beating another . during the space race , funding for research and education , in general , increased dramatically , leading to many advances that may not have otherwise been made . many nasa technologies developed for space are now widely used in civilian life , from memory foam in mattresses to freeze-dried food , to leds in cancer treatment . and , of course , the satellites that we rely on for our gps and mobile phone signals would not have been there without the space program . all of which goes to show that the rewards of scientific research and advancement are often far more vast than even the people pursuing them can imagine .
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and by august 1957 , the soviet 's successfully tested the first intercontinental ballistic missile , the r-7 , the same rocket that would be used to launch sputnik two months later . so , the scary thing about sputnik was not the orbiting ball itself , but the fact that the same technology could be used to launch a nuclear warhead at any city . not wanting to fall too far behind , president eisenhower ordered the navy to speed up its own project and launch a satellite as soon as possible .
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what was so scary about sputnik ?
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can plants talk to each other ? it certainly does n't seem that way . plants do n't have complex sensory or nervous systems like animals do , and they look pretty passive , basking in the sun , and responding instinctively to inputs like light and water . but odd as it sounds , plants can communicate with each other . just like animals , plants produce all kinds of chemical signals in response to their environments , and they can share those signals with each other , especially when they 're under attack . these signals take two routes : through the air , and through the soil . when plant leaves get damaged , whether by hungry insects or an invading lawn mower , they release plumes of volatile chemicals . they 're what 's responsible for the smell of freshly cut grass . certain kinds of plants , like sagebrush and lima beans , are able to pick up on those airborne messages and adjust their own internal chemistry accordingly . in one experiment , sagebrush leaves were deliberately damaged by insects or scissor-wielding scientists . throughout the summer , other branches on the same sagebrush plant got eaten less by insects wandering through , and so did branches on neighboring bushes , suggesting that they had beefed up their anti-insect defenses . even moving the air from above a clipped plant to another one made the second plant more insect-resistant . these airborne cues increase the likelihood of seedling survival , and made adult plants produce more new branches and flowers . but why would a plant warn its neighbors of danger , especially if they 're competing for resources ? well , it might be an accidental consequence of a self-defense mechanism . plants ca n't move information through their bodies as easily as we can , especially if water is scarce . so plants may rely on those airborne chemicals to get messages from one part of a plant to another . nearby plants can eavesdrop on those signals , like overhearing your neighbor sneeze and stocking up on cold medicine . different plants convey those warnings using different chemical languages . individual sagebrush plants in the same meadow release slightly different sets of alarm chemicals . the makeup of that cocktail influences the effectiveness of communication . the more similar two plants ' chemical fingerprints are , the more fluently they can communicate . a plant will be most sensitive to the cues emitted by its own leaves . but because these chemicals seem to be inherited , like human blood types , sagebrush plants communicate more effectively with relatives than with strangers . but sometimes , even other species can benefit . tomato and tobacco plants can both decipher sagebrush warning signals . plants do n't have to rely solely on those airborne broadcasts . signals can travel below the soil surface , too . most plants have a symbiotic relationship with fungi , which colonize the plants ' roots and help them absorb water and nutrients . these fungal filaments form extensive networks that can connect separate plants , creating an underground super highway for chemical messages . when a tomato plant responds to blight by acitvating disease-fighting genes and enzymes , signaling molecules produced by its immune system can travel to a healthy plant and prompt it to turn on its immune system , too . these advance warnings increase the plants chance of survival . bean plants also eavesdrop on each other 's health through these fungal conduits . an aphid investation in one plant triggers its neighbor to ramp up production of compounds that repel aphids and attract aphid-eating wasps . if you think of communication as an exchange of information , then plants seem to be active communicators . they 're sending , receiving , and responding to signals without making a sound , and without brains , noses , dictionaries , or the internet . and if we can learn to speak to them on their terms , we may gain a powerful new tool to protect crops and other valuable species . it all makes you wonder what else are we missing ?
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when a tomato plant responds to blight by acitvating disease-fighting genes and enzymes , signaling molecules produced by its immune system can travel to a healthy plant and prompt it to turn on its immune system , too . these advance warnings increase the plants chance of survival . bean plants also eavesdrop on each other 's health through these fungal conduits .
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why do plants communicate ? what advantages might they get from communicating that increase their chances of survival and reproduction ?
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for most of history , humans had no idea what purpose the heart served . in fact , the organ so confused leonardo da vinci , that he gave up studying it . although everyone could feel their own heart beating , it was n't always clear what each thump was achieving . now we know that the heart pumps blood . but that fact was n't always obvious , because if a heart was exposed or taken out , the body would perish quickly . it 's also impossible to see through the blood vessels , and even if that were possible , the blood itself is opaque , making it difficult to see the heart valves working . even in the 21st century , only a few people in surgery teams have actually seen a working heart . internet searches for heart function , point to crude models , diagrams or animations that do n't really show how it works . it 's as if there has been a centuries old conspiracy amongst teachers and students to accept that heart function can not be demonstrated . meaning that the next best thing is simply to cut it open and label the parts . that way students might not fully grasp the way it works , but can superficially understand it , learning such concepts as the heart is a four-chambered organ , or potentially misleading statements like , mammals have a dual-circulation : one with blood going to the lungs and back , and another to the body and back . in reality , mammals have a figure-eight circulation . blood goes from one heart pump to the lungs , back to the second heart pump , which sends it to the body , and then back to the first pump . that 's an important difference because it marks two completely different morphologies . this confusion makes many students wary of the heart in biology lessons , thinking it signals an intimidating subject full of complicated names and diagrams . only those who end up studying medicine compeltely understand how it all actually works . that 's when its functions become apparent as medics get to observe the motion of the heart 's valves . so , let 's imagine you 're a medic for a day . what you 'll need to get started is a whole fresh heart , like one from a sheep or pig . immerse this heart in water and you 'll see that it does n't pump when squeezed by hand . that 's because water does n't enter the heart cleanly enough for the pumping mechanism to work . we can solve this problem in an extraordinarly simple way . simply identify the two atria and cut them off , trimming them down to the tops of the ventricles . this makes the heart look less complicated because the atria have several incoming veins attached . so without them there , the only vessels remaining are the two major heart arteries : the aorta and pulmonary artery , which rise like white columns from between the ventricles . it looks -- and really is -- very simple . if you run water into the right ventricle from a tap ( the left also works , but less spectacularly ) , you 'll see that the ventricular valve tries to close against the incoming stream . and then ventricle inflates with water . squeeze the ventricle and a stream of water squirts out of the pulmonary artery . the ventricular valves , called the tricuspid in the right ventricle and the mitral in the left , can be seen through the clear water opening and closing like parachutes as the ventricle is rhythmically squeezed . this flow of water mimics the flow of blood in life . the valves are completely efficient . you 'll notice they do n't leak at all when the ventricles are squeezed . over time , they also close against each other with very little wear and tear , which explains how this mechanism continues to work seamlessly for more than 2 billion beats a heart gives in its lifetime . now , anyone studying the heart can hold one in their hands , make it pump for real and watch the action unfold . so place your hand above your own and feel its rhymic beat . understanding how this dependable inner pump works gives new resonance to the feeling you get when you run a race , drink too much caffeine or catch the eye of the one you love .
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although everyone could feel their own heart beating , it was n't always clear what each thump was achieving . now we know that the heart pumps blood . but that fact was n't always obvious , because if a heart was exposed or taken out , the body would perish quickly .
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as arteries carry blood away from the heart , they branch and become thinner and thinner until they become microscopic capillaries . these capillaries then join together and thicken as they become the veins that carry the blood back to the heart . the arteries have smooth walls , but the veins have valves that stop the blood from moving backwards . why do veins need valves , when arteries don ’ t ? what has that to do with capillaries ?
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if you 've ever floated on an ocean swell , you 'll know that the sea moves constantly . zoom out , and you 'll see the larger picture : our earth , covered by 71 percent water , moving in one enormous current around the planet . this intimidating global conveyor belt has many complicated drivers , but behind it all is a simple pump that moves water all over the earth . the process is called thermohaline circulation , and it 's driven by a basic concept : the concentration gradient . let 's leave the ocean for one moment and imagine we 're in an empty room with lots of roombas sardined together in one corner . turn them all on at once and the machines glide outwards bumping into and away from each other until the room is filled with an evenly spaced distribution . the machines have moved randomly towards equilibrium , a place where the concentration of a substance is equally spread out . that 's what happens along a concentration gradient , as substances shift passively from a high , or squashed , concentration , to a lower , more comfortable one . how does this relate to ocean currents and thermohaline circulation ? thermo means temperature , and haline means salt because in the real world scenario of the sea , temperature and salinity drive the shift from high to low concentrations . let 's put you back in the ocean to see how this works . snap ! you 're transformed into a molecule of surface water , off the temperate coast of new york surrounded by a zillion rowdy others . here , the sun 's rays act as an energizer that set you and the other water molecules jostling about , bouncing off each other like the roombas did . the more you spread out , the less concentrated the water molecules at the surface become . through this passive motion , you move from a high to a lower concentration . let 's suspend the laws of physics for a moment , and pretend that your molecular self can plunge deep down into the water column . in these colder depths , the comparative lack of solar warmth makes water molecules sluggish , meaning they can sit quite still at high concentrations . no jostling here . but seeking relief from the cramped conditions they 're in , they soon start moving upwards towards the roomier situation at the surface . this is how temperature drives a shift of water molecules from high to low concentrations , towards equilibrium . but sea water is made up of more than just h2o . there are a great deal of salt ions in it as well . and like you , these guys have a similar desire for spacious real estate . as the sun warms the sea , some of your fellow water molecules evaporate from the surface , increasing the ration of salt to h2o . the crowded salt ions left behind notice that lower down , salt molecules seem to be enjoying more space . and so an invasion begins , as they too move downwards in the water column . in the polar regions , we see how this small local process effects global movement . in the arctic and antarctic , where ice slabs decorate the water 's surface , there 's little temperature difference between surface and deeper waters . it 's all pretty cold . but salinity differs , and in this scenario , that 's what triggers the action . here , the sun 's rays melt surface ice , depositing a new load of water molecules into the sea . that not only increases the proximity between you and other water molecules , leaving you vying for space again , but it also conversely dilutes the concentration of salt ions . so , down you go , riding along the concentration gradient towards more comfortable conditions . for salt ions , however , their lower concentration at the surface , acts like an advertisement to the clamoring masses of salt molecules below who begin their assent . in both temperate and polar regions , this passive motion along a concentration gradient , can get a current going . and that is the starting point of the global conveyor called thermohaline circulation . this is how a simple concept becomes the mechanism underlying one of the largest and most important systems on our planet . and if you look around , you 'll see it happening everywhere . turn on a light , and it 's there . concentration gradients govern the flow of electricity , allowing electrons squashed together in one space to travel to an area of lower concentration when a channel is opened , which you do by flipping a switch . right now , in fact , there 's some gradient action going on inside you as you breath air into your lungs letting the concentrated oxygen in that air move passively out of your lungs and into your blood stream . we know that the world is filled with complex physical problems , but sometimes the first step towards understanding them can be simple . so when you confront the magnitude of the ocean 's currents , or have to figure out how electricity works , remember not to panic . understanding can be as simple as flipping a switch .
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so , down you go , riding along the concentration gradient towards more comfortable conditions . for salt ions , however , their lower concentration at the surface , acts like an advertisement to the clamoring masses of salt molecules below who begin their assent . in both temperate and polar regions , this passive motion along a concentration gradient , can get a current going . and that is the starting point of the global conveyor called thermohaline circulation .
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in polar regions , the concentration of h2o molecules is highest :
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in this dystopian world , your resistance group is humanity 's last hope . unfortunately , you 've all been captured by the tyrannical rulers and brought to the ancient colosseum for their deadly entertainment . before you 're thrown into the dungeon , you see many numbered hallways leading outside . but each exit is blocked by an electric barrier with a combination keypad . you learn that one of you will be allowed to try to escape by passing a challenge while everyone else will be fed to the mutant salamanders the next morning . with her perfect logical reasoning , zara is the obvious choice . you hand her a concealed audio transmitter so that the rest of you can listen along . as zara is led away , you hear her footsteps echo through one of the hallways , then stop . a voice announces that she must enter a code consisting of three positive whole numbers in ascending order , so the second number is greater than or equal to the first , and the third is greater than or equal to the second . she may ask for up to three clues , but if she makes a wrong guess , or says anything else , she 'll be thrown back into the dungeon . for the first clue , the voice says the product of the three numbers is 36 . when zara asks for the second clue , it tells her the sum of the numbers is the same as the number of the hallway she entered . there 's a long silence . you 're sure zara remembers the hallway number , but there 's no way for you to know it , and she ca n't say it outloud . if zara could enter the passcode at this point , she would , but instead , she asks for the third clue , and the voice announces that the largest number appears only once in the combination . moments later , the buzz of the electric barrier stops for a few seconds , and you realize that zara has escaped . unfortunately , her transmitter is no longer in range , so that 's all the information you get . can you find the solution ? pause on the next screen to work out the solution . 3 2 1 you 're worried about the fact that you do n't know zara 's hallway number , but you decide to start from the beginning anyways . from the first clue , you work out all of the eight possible combinations that come out to a product of 36 . one of these must be right , but which one ? now comes the hard part . even though you do n't know which number you 're looking for , you decide to work out the sum of each combination 's three numbers . that 's when it hits you . all but two of the sums are unique , and if the hallway number had matched any of these , zara would have known the correct combination right then and there without asking for the third clue . since she did ask for the clue , the hallway number must have matched the only sum that appears more than once in the list : thirteen . but which of the two combinations that add up to thirteen is correct : 1,6,6 , or 2,2,9 ? that 's where the third clue comes in . since it tells us that the largest number must be unique , 2,2,9 must be the code . when night falls , you and the others escape through hallway thirteen and rejoin zara outside . you 've freed yourselves through math and logic . now it 's time to free the rest of the world .
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she may ask for up to three clues , but if she makes a wrong guess , or says anything else , she 'll be thrown back into the dungeon . for the first clue , the voice says the product of the three numbers is 36 . when zara asks for the second clue , it tells her the sum of the numbers is the same as the number of the hallway she entered .
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in the lesson , we wrote 36 as a product combination of 3 natural numbers . what is the best way to write down all the possible products and make sure we haven ’ t missed any ?
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think about how your favorite stories hook you . `` when he was nearly 13 , my brother jim got his arm badly broken at the elbow . when it healed , and jim 's fears of never being able to play football were assuaged , he was seldom self conscious about his injury . '' `` all this happened , more or less . the war parts , anyway , are pretty much true . one guy i knew really was shot in dresden for taking a teapot that was n't his . '' `` my father 's family name being pirrip , and my christian name philip , my infant tongue could make of both names nothing longer or more explicit than 'pip . ' so i called myself pip , and came to be called pip . '' imagery , intrigue , emotion : each introduction makes you want to read more . if you have an assignment to write a literary analysis , your introduction will be just as important . there will be four elements in your essay : your introduction , thesis statement , analysis and conclusion . if you begin writing a literary analysis with the introduction , you may be discouraged . here 's a tip for writing a great introduction : write it last , and write your thesis first . figure out what you want to analyze before you actually analyze it . your thesis is the foundation for the rest of your essay , including your introduction . so how do you find your thesis ? start by asking questions . to charles dickens you may ask , `` why do you draw attention to characters ' hands ? '' `` what 's up with their names ? '' `` pumblechook ? really ? '' to narrow your concept for analysis , answer the questions yourself . `` estella ridicules pip 's hands , jaggers constantly washes his hands , pip insufferably burns his hands , mrs. joe brings pip up by hand . '' are there patterns in your answers ? `` estella 's comments smack of cruelty , while jaggers ' cleanses his immoral conscience . pip finds a second chance , while mrs. joe abuses a child under the guise of love and dedication . '' what can you analyze with this pattern ? `` hands symbolize social class inequities , and through dickens ' criticism , he exposes the dire need for reform in victorian london . what you will do next , which is an entirely different lesson , is to draft and revise your analysis . only after you write your analysis , return to your introduction . like authors earlier , try to intrigue and inspire your reader . avoid starting with famous quotations , dictionary definitions or rhetorical questions . consider the historical context of your topic , or an anecdote or some larger idea or concept . here 's an example : `` 27 bones in the hand and wrist allow humans to concurrently create and destroy . thousands of hands have been behind history 's astounding creations . hands represent a powerful symbol , one that was not lost on charles dickens . in great expectations , dickens uses hands to symbolize social class inequities , and through his criticism , he exposes the dire need for social reform in victorian london . '' take time crafting and revising your thesis and introduction . remember , if you are bored while writing , your reader will be bored while reading . by the way , did you notice the introduction to this lesson ? it did n't start with `` here 's how to write a thesis and introduction . '' would that have hooked you ?
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take time crafting and revising your thesis and introduction . remember , if you are bored while writing , your reader will be bored while reading . by the way , did you notice the introduction to this lesson ?
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do you prefer reading or writing ? explain why .
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which of these entities has evolved the ability to manipulate an animal many times its size ? the answer is all of them . these are all parasites , organisms that live on or inside another host organism , which they harm and sometimes even kill . parasite survival depends on transmitting from one host to the next , sometimes through an intermediate species . our parasites elegantly achieve this by manipulating their host 's behavior , sometimes through direct brain hijacking . for example , this is the gordian worm . one of its hosts , this cricket . the gordian worm needs water to mate , but the cricket prefers dry land . so once it 's big enough to reproduce , the worm produces proteins that garble the cricket 's navigational system . the confused cricket jumps around erratically , moves closer to water , and eventually leaps in , often drowning in the process . the worm then wriggles out to mate and its eggs get eaten by little water insects that mature , colonize land , and are , in turn , eaten by new crickets . and thus , the gordian worm lives on . and here 's the rabies virus , another mind-altering parasite . this virus infects mammals , often dogs , and travels up the animal 's nerves to its brain where it causes inflammation that eventually kills the host . but before it does , it often increases its host 's aggressiveness and ramps up the production of rabies-transmitting saliva , while making it hard to swallow . these factors make the host more likely to bite another animal and more likely to pass the virus on when it does . and now , meet ophiocordyceps , also known as the zombie fungus . its host of choice is tropical ants that normally live in treetops . after ophiocordyceps spores pierce the ant 's exoskeleton , they set off convulsions that make the ant fall from the tree . the fungus changes the ant 's behavior , compelling it to wander mindlessly until it stumbles onto a plant leaf with the perfect fungal breeding conditions , which it latches onto . the ant then dies , and the fungus parasitizes its body to build a tall , thin stalk from its neck . within several weeks , the stalk shoots off spores , which turn more ants into six-legged leaf-seeking zombies . one of humanity 's most deadly assailants is a behavior-altering parasite , though if it 's any consolation , it 's not our brains that are being hijacked . i 'm talking about plasmodium , which causes malaria . this parasite needs mosquitoes to shuttle it between hosts , so it makes them bite more frequently and for longer . there 's also evidence that humans infected with malaria are more attractive to mosquitoes , which will bite them and transfer the parasite further . this multi-species system is so effective , that there are hundreds of millions of malaria cases every year . and finally , there are cats . do n't worry , there probably are n't any cats living in your body and controlling your thoughts . i mean , probably . but there is a microorganism called toxoplasma that needs both cats and rodents to complete its life cycle . when a rat gets infected by eating cat feces , the parasite changes chemical levels in the rat 's brain , making it less cautious around the hungry felines , maybe even attracted to them . this makes them easy prey , so these infected rodents get eaten and pass the parasite on . mind control successful . there 's even evidence that the parasite affects human behavior . in most cases , we do n't completely understand how these parasites manage their feats of behavior modification . but from what we do know , we can tell that they have a pretty diverse toolbox . gordian worms seem to affect crickets ' brains directly . the malaria parasite , on the other hand , blocks an enzyme that helps the mosquitoes feed , forcing them to bite over and over and over again . the rabies virus may cause that snarling , slobbering behavior by putting the immune system into overdrive . but whatever the method , when you think about how effectively these parasites control the behavior of their hosts , you may wonder how much of human behavior is actually parasites doing the talking . since more than half of the species on earth are parasites , it could be more than we think .
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these are all parasites , organisms that live on or inside another host organism , which they harm and sometimes even kill . parasite survival depends on transmitting from one host to the next , sometimes through an intermediate species . our parasites elegantly achieve this by manipulating their host 's behavior , sometimes through direct brain hijacking .
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tsetse flies transmit the protozoan parasite that causes african sleeping sickness in humans . what type of host manipulation may you expect to see here ?
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cramming for a test ? trying to get more done than you have time to do ? stress is a feeling we all experience when we are challenged or overwhelmed . but more than just an emotion , stress is a hardwired physical response that travels throughout your entire body . in the short term , stress can be advantageous , but when activated too often or too long , your primitive fight or flight stress response not only changes your brain but also damages many of the other organs and cells throughout your body . your adrenal gland releases the stress hormones cortisol , epinephrine , also known as adrenaline , and norepinephrine . as these hormones travel through your blood stream , they easily reach your blood vessels and heart . adrenaline causes your heart to beat faster and raises your blood pressure , over time causing hypertension . cortisol can also cause the endothelium , or inner lining of blood vessels , to not function normally . scientists now know that this is an early step in triggering the process of atherosclerosis or cholesterol plaque build up in your arteries . together , these changes increase your chances of a heart attack or stroke . when your brain senses stress , it activates your autonomic nervous system . through this network of nerve connections , your big brain communicates stress to your enteric , or intestinal nervous system . besides causing butterflies in your stomach , this brain-gut connection can disturb the natural rhythmic contractions that move food through your gut , leading to irritable bowel syndrome , and can increase your gut sensitivity to acid , making you more likely to feel heartburn . via the gut 's nervous system , stress can also change the composition and function of your gut bacteria , which may affect your digestive and overall health . speaking of digestion , does chronic stress affect your waistline ? well , yes . cortisol can increase your appetite . it tells your body to replenish your energy stores with energy dense foods and carbs , causing you to crave comfort foods . high levels of cortisol can also cause you to put on those extra calories as visceral or deep belly fat . this type of fat does n't just make it harder to button your pants . it is an organ that actively releases hormones and immune system chemicals called cytokines that can increase your risk of developing chronic diseases , such as heart disease and insulin resistance . meanwhile , stress hormones affect immune cells in a variety of ways . initially , they help prepare to fight invaders and heal after injury , but chronic stress can dampen function of some immune cells , make you more susceptible to infections , and slow the rate you heal . want to live a long life ? you may have to curb your chronic stress . that 's because it has even been associated with shortened telomeres , the shoelace tip ends of chromosomes that measure a cell 's age . telomeres cap chromosomes to allow dna to get copied every time a cell divides without damaging the cell 's genetic code , and they shorten with each cell division . when telomeres become too short , a cell can no longer divide and it dies . as if all that were n't enough , chronic stress has even more ways it can sabotage your health , including acne , hair loss , sexual dysfunction , headaches , muscle tension , difficulty concentrating , fatigue , and irritability . so , what does all this mean for you ? your life will always be filled with stressful situations . but what matters to your brain and entire body is how you respond to that stress . if you can view those situations as challenges you can control and master , rather than as threats that are insurmountable , you will perform better in the short run and stay healthy in the long run .
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you may have to curb your chronic stress . that 's because it has even been associated with shortened telomeres , the shoelace tip ends of chromosomes that measure a cell 's age . telomeres cap chromosomes to allow dna to get copied every time a cell divides without damaging the cell 's genetic code , and they shorten with each cell division .
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telomeres , the shoelace tip ends on chromosomes :
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for the microscopic lab worm , c. elegans life equates to just a few short weeks on earth . compare that with the tortoise , which can age to more than 100 years . mice and rats reach the end of their lives after just four years , while for the bowhead whale , earth 's longest-lived mammal , death can come after 200 . like most living things , the vast majority of animals gradually degenerate after reaching sexual maturity in the process known as aging . but what does it really mean to age ? the drivers behind this process are varied and complicated , but aging is ultimately caused by cell death and dysfunction . when we 're young , we constantly regenerate cells in order to replace dead and dying ones . but as we age , this process slows down . in addition , older cells do n't perform their functions as well as young ones . that makes our bodies go into a decline , which eventually results in disease and death . but if that 's consistently true , why the huge variance in aging patterns and lifespan within the animal kingdom ? the answer lies in several factors , including environment and body size . these can place powerful evolutionary pressures on animals to adapt , which in turn makes the aging process different across species . consider the cold depths of the atlantic and arctic seas , where greenland sharks can live to over 400 years , and the arctic clam known as the quahog can live up to 500 . perhaps the most impressive of these ocean-dwelling ancients is the antarctic glass sponge , which can survive over 10,000 years in frigid waters . in cold environments like these , heartbeats and metabolic rates slow down . researchers theorize that this also causes a slowing of the aging process . in this way , the environment shapes longevity . when it comes to size , it 's often , but not always , the case that larger species have a longer lifespan than smaller ones . for instance , an elephant or whale will live much longer than a mouse , rat , or vole , which in turn have years on flies and worms . some small animals , like worms and flies , are also limited by the mechanics of their cell division . they 're mostly made up of cells that ca n't divide and be replaced when damaged , so their bodies expire more quickly . and size is a powerful evolutionary driver in animals . smaller creatures are more prone to predators . a mouse , for instance , can hardly expect to survive more than a year in the wild . so , it has evolved to grow and reproduce more rapidly , like an evolutionary defense mechanism against its shorter lifespan . larger animals , by contrast , are better at fending off predators , and so they have the luxury of time to grow to large sizes and reproduce multiple times during their lives . exceptions to the size rule include bats , birds , moles , and turtles , but in each case , these animals have other adaptations that allow them to escape predators . but there are still cases where animals with similar defining features , like size and habitat , age at completely different rates . in these cases , genetic differences , like how each organism 's cells respond to threats , often account for the discrepancies in longevity . so it 's the combination of all these factors playing out to differing degrees in different animals that explains the variability we see in the animal kingdom . so what about us ? humans currently have an average life expectancy of 71 years , meaning that we 're not even close to being the longest living inhabitants on earth . but we are very good at increasing our life expectancy . in the early 1900s , humans only lived an average of 50 years . since then , we 've learned to adapt by managing many of the factors that cause deaths , like environmental exposure and nutrition . this , and other increases in life expectancy make us possibly the only species on earth to take control over our natural fate .
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that makes our bodies go into a decline , which eventually results in disease and death . but if that 's consistently true , why the huge variance in aging patterns and lifespan within the animal kingdom ? the answer lies in several factors , including environment and body size . these can place powerful evolutionary pressures on animals to adapt , which in turn makes the aging process different across species .
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which of the following factors is not thought to contribute to aging ?
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what 's your sign ? in western astrology , it 's a constellation determined by when your birthday falls in the calendar . but according to the chinese zodiac , or shēngxiào , it 's your shǔxiàng , meaning the animal assigned to your birth year . and of the many myths explaining these animal signs and their arrangement , the most enduring one is that of the great race . as the story goes , yù dì , or jade emperor , ruler of the heavens , wanted to devise a way to measure time , so he organized a race . the first twelve animals to make it across the river would earn a spot on the zodiac calendar in the order they arrived . the rat rose with the sun to get an early start , but on the way to the river , he met the horse , the tiger , and the ox . because the rat was small and could n't swim very well , he asked the bigger animals for help . while the tiger and horse refused , the kind-hearted ox agreed to carry the rat across . yet , just as they were about to reach the other side , the rat jumped off the ox 's head and secured first place . the ox came in second , with the powerful tiger right behind him . the rabbit , too small to battle the current , nimbly hopped across stones and logs to come in fourth . next came the dragon , who could have flown directly across , but stopped to help some creatures she had encountered on the way . after her came the horse , galloping across the river . but just as she got across , the snake slithered by . the startled horse reared back , letting the snake sneak into sixth place . the jade emperor looked out at the river and spotted the sheep , the monkey , and the rooster all atop a raft , working together to push it through the weeds . when they made it across , the trio agreed to give eighth place to the sheep , who had been the most comforting and harmonious of them , followed by the monkey and the rooster . next came the dog , scrambling onto the shore . he was a great swimmer , but frolicked in the water for so long that he only managed to come in eleventh . the final spot was claimed by the pig , who had gotten hungry and stopped to eat and nap before finally waddling across the finish line . and so , each year is associated with one of the animals in this order , with the cycle starting over every 60 years . why 60 and not twelve ? well , the traditional chinese calendar is made up of two overlapping systems . the animals of the zodiac are associated with what 's called the twelve earthly branches , or shí'èrzhī . another system , the ten heavenly stems , or tiāngān , is linked with the five classical elements of metal , xīn , wood , mù , water , shuǐ , fire , huǒ , and earth , tǔ . each element is assigned yīn or yáng , creating a ten-year cycle . when the twelve animals of the earthly branches are matched with the five elements plus the yīn or the yáng of the heavenly stems , it creates 60 years of different combinations , known as a sexagenary cycle , or gānzhī . so someone born in 1980 would have the sign of yáng metal monkey , while someone born in 2007 would be yīn fire pig . in fact , you can also have an inner animal based on your birth month , a true animal based on your birth date , and a secret animal based on your birth hour . it was the great race that supposedly determined which animals were enshrined in the chinese zodiac , but as the system spread through asia , other cultures made changes to reflect their communities . so if you consult the vietnamese zodiac , you may discover that you 're a cat , not a rabbit , and if you 're in thailand , a mythical snake called a naga replaces the dragon . so whether or not you place stock in what the zodiac says about you as an individual , it certainly reveals much about the culture it comes from .
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in fact , you can also have an inner animal based on your birth month , a true animal based on your birth date , and a secret animal based on your birth hour . it was the great race that supposedly determined which animals were enshrined in the chinese zodiac , but as the system spread through asia , other cultures made changes to reflect their communities . so if you consult the vietnamese zodiac , you may discover that you 're a cat , not a rabbit , and if you 're in thailand , a mythical snake called a naga replaces the dragon .
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how has the chinese zodiac changed as it spread through asia ?
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`` hey , another atom . i 'm hydrogen , nice to meet you . how are you feeling about the jump ? '' `` hi there , i 'm antihydrogen , your antiatom , and to be honest , i 'm feeling kind of neutral . my positron and antiproton balance out , just like your electron and proton , right ? '' `` hey , yeah ! you look just like me , but different somehow . '' `` whoa , be careful ! if we get too close , we 'll disappear in a spark of energy . i 'd like to stay in one piece . '' `` oh wow , sorry . '' `` it 's okay . i was just thinking , it 's kind of weird for us to be chatting like this before our jump above cern . '' `` why 's that ? '' `` well , for starters , how do we know we 'll both fall ? '' `` of course we 'll fall . it 's gravity , you know , the force of attraction between masses . i even know how fast we should fall . galileo showed in that tower experiment that all falling objects accelerate at the same rate , regardless of mass . '' `` that 's for bigger objects . it 's a different story for small particles like us . our mass is so tiny that the gravitational force we experience is miniscule , and if the particles are charged , like my antiproton or your proton , then it becomes impossible to detect compared to the much greater electromagnetic force acting on them . '' `` but that 's only for charged particles . you and i are both neutral . our charges balance out , so the electromagnetic force is small and the gravitational force should be detectable . i know mine 's been measured . '' `` because you 're everywhere , but i 'm kind of hard to find . '' `` why is that , anyway ? should n't there have been an equal amount of matter and antimatter created in the big bang ? '' `` you 'd think so , but then all of those particles would have annihilated each other into energy , remember ? and the universe is obviously full of matter . no one knows why there is more matter than antimatter , which is why scientists are so interested in studying me . '' `` so where do they find you anyway ? '' `` actually , i was made in that lab down there . they needed an accelerator to make my antiproton because it 's so heavy , just as heavy as your proton . getting my positron was easier . it 's much lighter , like your electron , and there are materials that naturally decay by emitting one . then they just had to put the two together and they got me . but it 's only recently that they 've been able to keep me around long enough to study my properties . '' `` and now they 've sent you on this jump with me . hey , wait a minute . '' `` that 's right . we 're reenacting galileo 's experiment , but with matter and antimatter instead of two objects made of matter . '' `` so what 's going to happen ? are you going to fall upwards or something ? '' `` only one way to find out ! ''
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should n't there have been an equal amount of matter and antimatter created in the big bang ? '' `` you 'd think so , but then all of those particles would have annihilated each other into energy , remember ? and the universe is obviously full of matter .
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by observing the behavior of antihydrogen in the earth ; s gravitational field , what do physicists want to measure ? how do you think they could perform the experiment ?
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how did dracula become the world 's most famous vampire ? more than 100 years after his creator was laid to rest , dracula lives on as the most famous vampire in history . but this transylvanian noble , neither the first fictional vampire nor the most popular of his time , may have remained buried in obscurity if not for a twist of fate . dracula 's first appearance was in bram stoker 's 1897 novel of the same name . but that was far from the beginning of vampire myths . blood-sucking monsters had already been part of folklore for at least 800 years . it was slavic folklore that gave us the word vampire , or `` upir '' in old russian . the term 's first known written mention comes from the 11th century . vampire lore in the region predated christianity 's arrival and persisted despite the church 's efforts to eliminate pagan beliefs . stories of vampires originated from misinterpretations of diseases , such as rabies , and pellagra , and decomposition . in the case of the latter , gasses swelling the body and blood oozing from the mouth could make a corpse look like it had recently been alive and feeding . vampires were describe as bloated with overgrown teeth and nails . this gave rise to many rituals intended to prevent the dead from rising , such as burying bodies with garlic or poppyseeds , as well as having them staked , burned , or mutilated . vampire lore remained a local phenomenon until the 18th century when serbia was caught in the struggle between two great powers , the habsburg monarchy and ottoman empire . austrian soldiers and government officials observed and documented the strange local burial rituals , and their reports became widely publicized . the resulting vampire hysteria got so out of hand that in 1755 , the austrian empress was forced to dispatch her personal physician . he investigated and put an end to the rumors by publishing a thorough , scientific refutation . the panic subsided , but the vampire had already taken root in western europe 's imagination , spawning works like `` the vampyre '' in 1819 , and joseph sheridan le fanu 's `` carmilla '' in 1872 . this book would greatly influence a young irish drama critic named bram stoker . stoker , who was born in dublin in 1847 , was famously bedridden with an unknown illness until the age of seven . during that time , his mother told him folktales and true tales of horror , including her experiences during an outbreak of cholera in 1832 . there , she described victims buried alive in mass graves . later in his life , stoker went on to write fantasy , romance , adventure stories , and , in 1897 , `` dracula . '' although the book 's main villain and namesake is thought to be based on the historical figure of vlad iii dracula , or vlad the impaler , the association is mostly just that they share a name . other elements and characters were inspired directly and indirectly by various works in the victorian era , such as `` the mysterious stranger . '' the novel , upon release , was only a moderate success in its day , nor was it even stoker 's most well-known work , mentioned only briefly in a 1912 obituary . but a critical copyright battle would completely change dracula 's fate , and catapult the character into literary renown . in 1922 , a german studio adapted the novel into the now classic silent film `` nosferatu '' without paying royalties . despite changes in character names and minor plot points , the parallels were obvious , and the studio was sued into bankruptcy . to prevent more plagiarism attempts , stoker 's widow decided to establish copyright over the stage version of `` dracula '' by approving a production by family-friend hamilton deane . although deane 's adaptation made drastic cuts to the story , it became a classic , thanks largely to bela lugosi 's performance on broadway . lugosi would go on to star in the 1931 film version by universal , lending the character many of his signature characteristics . and since then , dracula has risen again in countless adaptations , finding eternal life far beyond the humble pages of his birth .
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dracula 's first appearance was in bram stoker 's 1897 novel of the same name . but that was far from the beginning of vampire myths . blood-sucking monsters had already been part of folklore for at least 800 years . it was slavic folklore that gave us the word vampire , or `` upir '' in old russian . the term 's first known written mention comes from the 11th century .
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what does the struggle between the hapsburgs and the ottomans suggest about the spreading of vampire folklore inside , and outside , of eastern europe ?
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myths and misconceptions about evolution . let 's talk about evolution . you 've probably heard that some people consider it controversial , even though most scientists do n't . but even if you are n't one of those people and you think you have a pretty good understanding of evolution , chances are you still believe some things about it that are n't entirely right , things like , `` evolution is organisms adapting to their environment . '' this was an earlier , now discredited , theory of evolution . almost 60 years before darwin published his book , jean-baptiste lamarck proposed that creatures evolve by developing certain traits over their lifetimes and then passing those on to their offspring . for example , he thought that because giraffes spent their lives stretching to reach leaves on higher branches , their children would be born with longer necks . but we know now that 's not how genetic inheritance works . in fact , individual organisms do n't evolve at all . instead , random genetic mutations cause some giraffes to be born with longer necks , and that gives them a better chance to survive than the ones who were n't so lucky , which brings us to `` survival of the fittest '' . this makes it sound like evolution always favors the biggest , strongest , or fastest creatures , which is not really the case . for one thing , evolutionary fitness is just a matter of how well-suited they are to their current environment . if all the tall trees suddenly died out and only short grass was left , all those long-necked giraffes would be at a disadvantage . secondly , survival is not how evolution occurs , reproduction is . and the world if full of creatures like the male anglerfish , which is so small and ill-suited for survival at birth that it has to quickly find a mate before it dies . but at least we can say that if an organism dies without reproducing , it 's evolutionarily useless , right ? wrong ! remember , natural selection happens not at the organism level , but at the genetic level , and the same gene that exists in one organism will also exist in its relatives . so , a gene that makes an animal altruistically sacrifice itself to help the survival and future reproduction of its siblings or cousins , can become more widespread than one that is solely concerned with self-preservation . anything that lets more copies of the gene pass on to the next generation will serve its purpose , except evolutionary purpose . one of the most difficult things to keep in mind about evolution is that when we say things like , `` genes want to make more copies of themselves , '' or even , `` natural selection , '' we 're actually using metaphors . a gene does n't want anything , and there 's no outside mechanism that selects which genes are best to preserve . all that happens is that random genetic mutations cause the organisms carrying them to behave or develop in different ways . some of those ways result in more copies of the mutated gene being passed on , and so forth . nor is there any predetermined plan progressing towards an ideal form . it 's not ideal for the human eye to have a blind spot where the optic nerve exits the retina , but that 's how it developed , starting from a simple photoreceptor cell . in retrospect , it would have been much more advantageous for humans to crave nutrients and vitamins rather than just calories . but over the millenia , during which our ancestors evolved , calories were scarce , and there was nothing to anticipate that this would later change so quickly . so , evolution proceeds blindly , step by step by step , creating all of the diversity we see in the natural world .
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and the world if full of creatures like the male anglerfish , which is so small and ill-suited for survival at birth that it has to quickly find a mate before it dies . but at least we can say that if an organism dies without reproducing , it 's evolutionarily useless , right ? wrong !
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how can organisms that die without reproducing still propagate their genes ?
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is there a disease that makes us love cats , and do you have it ? maybe , and it 's more likely than you 'd think . we 're talking about toxoplasmosis , a disease caused by toxoplasma gondii . like all parasites , toxoplasma lives at the expense of its host , and needs its host to produce offspring . to do that , toxo orchestrates a brain manipulation scheme involving cats , their rodent prey , and virtually all other birds and mammals , including humans . documented human infections go as far back as ancient egypt . we found samples in mummies . today , about a third of the world 's population is infected , and most of them never even know it . in healthy people , symptoms often do n't show up at all . when they do , they 're mild and flu-like . but those are just the physical symptoms . toxoplasma also nestles into our brains and meddles with our behavior behind the scenes . to understand why , let 's take a look at the parasite 's life cycle . while the parasite can multiply in practically any host , it can only reproduce sexually in the intestines of cats . the offspring , called oocysts , are shed in the cat 's feces . a single cat can shed up to a hundred million oocysts . if another animal , like a mouse , accidentally ingests them , they 'll invade the mouse 's tissues and mature to form tissue cysts . if the mouse gets eaten by a cat , the tissue cysts become active and release offspring that mate to form new oocysts , completing the cycle . but there 's a problem . a mouse 's natural desire to avoid a cat makes it tough to close this loop . toxoplasma has a solution for that . the parasites invade white blood cells to hitch a ride to the brain where they seem to override the innate fear of predators . infected rodents are more reckless and have slower reaction times . strangest of all , they 're actually attracted to feline urine , which probably makes them more likely to cross paths with a cat and help the parasite complete its life cycle . how does the parasite pull this off ? although the exact mechanism is n't known , toxo appears to increase dopamine , a brain neurotransmitter that is involved in novelty-seeking behavior . thus , one idea is that toxo tinkers with neurotransmitters , the chemical signals that modulate emotions . the result ? fatal attraction . but mice are n't the only animals that end up with these parasites , and that 's where humans , and all of toxo 's other hosts , come in . we can accidentally ingest oocysts in contaminated water , or unwashed produce , or from playing in sandboxes , or cleaning out litter boxes . this is behind the common recommendation that pregnant women not change cat litter . toxo can cause serious birth defects . we can also get toxo from eating undercooked meat from other animals that picked up some oocysts . and it turns out that toxo can mess with our brains , too . studies have found connections between toxo and schizophrenia , biopolar disorder , obsessive compulsive disorder , and aggression . it also slows reactions and decreases concentration , which may be why one study found that people involved in traffic accidents were almost three times more likely to have toxoplasma . so is toxo manipulating our brains as an evolutionary strategy to get predatory cats to eat us ? or are our brains just similar enough to a rodent 's that the same neurological tricks that lure them in catch us in the net , too ? and is toxo the reason so many people love cats and keep them as pets ? well , the jury 's still out on that one . some recent studies even contradict the idea . regardless , toxoplasma has definitely benefited from humans to become one of the world 's most successful parasites . it 's not just our willingness to let cats on our dining room tables or in our beds . raising livestock and building cities which attract rodents has provided billions of new hosts , and you and your cat may be two of them .
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but those are just the physical symptoms . toxoplasma also nestles into our brains and meddles with our behavior behind the scenes . to understand why , let 's take a look at the parasite 's life cycle . while the parasite can multiply in practically any host , it can only reproduce sexually in the intestines of cats . the offspring , called oocysts , are shed in the cat 's feces .
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toxoplasma is one example of a parasite that can manipulate the behavior of its host to reproduce and therefore increase its own survival . another parasite that can manipulate host behavior is plasmodium , the causative agent of malaria . when mosquitoes are infected with plasmodium , they bite more often and for longer than mosquitoes that are not infected . provide a hypothesis for how this altered behavior helps the parasite .
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a girl i 've never met before changed my life and the life of thousands of other people . i 'm the ceo of dosomething.org . it 's one of the largest organizations in the world for young people . in fact it 's bigger than the boy scouts in the united states . and we 're not homophobic . ( laughter ) and it 's true -- the way we communicate with young people is by text , because that 's how young people communicate . so we 'll run over 200 campaigns this year , things like collecting peanut butter for food pantries , or making valentine 's day cards for senior citizens who are homebound . and we 'll text them . and we 'll have a 97 percent open rate . it 'll over-index hispanic and urban . we collected 200,000 jars of peanut butter and over 365,000 valentine 's day cards . this is big scale . ok -- ( applause ) but there 's one weird side effect . every time we send out a text message , we get back a few dozen text messages having nothing to do with peanut butter or hunger or senior citizens -- but text messages about being bullied , text messages about being addicted to pot . and the worst message we ever got said exactly this : `` he wo n't stop raping me . it 's my dad . he told me not to tell anyone . are you there ? '' we could n't believe this was happening . we could n't believe that something so horrific could happen to a human being , and that she would share it with us -- something so intimate , so personal . and we realized we had to stop triaging this and we had to build a crisis text line for these people in pain . so we launched crisis text line , very quietly , in chicago and el paso -- just a few thousand people in each market . and in four months , we were in all 295 area codes in america . just to put that into perspective , that 's zero marketing and faster growth than when facebook first launched . ( applause ) text is unbelievably private . no one hears you talking . so we spike everyday at lunch time -- kids are sitting at the lunch table and you think that she 's texting the cute boy across the hall , but she 's actually texting us about her bulimia . and we do n't get the word `` like '' or `` um '' or hyperventilating or crying . we just get facts . we get things like , `` i want to die . i have a bottle of pills on the desk in front of me . '' and so the crisis counselor says , `` how about you put those pills in the drawer while we text ? '' and they go back and forth for a while . and the crisis counselor gets the girl to give her her address , because if you 're texting a text line , you want help . so she gets the address and the counselor triggers an active rescue while they 're texting back and forth . and then it goes quiet -- 23 minutes with no response from this girl . and the next message that comes in says -- it 's the mom -- `` i had no idea , and i was in the house , we 're in an ambulance on our way to the hospital . '' as a mom that one just -- the next message comes a month later . `` i just got out of the hospital . i was diagnosed as bipolar , and i think i 'm going to be ok. '' ( applause ) i would love to tell you that that 's an unusual exchange , but we 're doing on average 2.41 active rescues a day . thirty percent of our text messages are about suicide and depression -- huge . the beautiful thing about crisis text line is that these are strangers counseling other strangers on the most intimate issues , and getting them from hot moments to cold moments . it 's exciting , and i will tell you that we have done a total of more than 6.5 million text messages in less than two years . ( applause ) but the thing that really gets me hot and sweaty about this , the thing that really gets me psyched is the data : 6.5 million messages -- that 's the volume , velocity and variety to provide a really juicy corpus . we can do things like predictive work . we can do all kinds of conclusions and learnings from that data set . so we can be better , and the world can be better . so how do we use the data to make us better ? alright , chances are someone here , someone watching this has seen a therapist or a shrink at some point in time in your life -- you do not have to raise your hand . ( laughter ) how do you know that person 's any good ? oh , they have a degree from harvard on the wall ? are you sure he did n't graduate in the bottom 10 percent ? ( laughter ) when my husband and i saw a marriage counselor , i thought she was a genius when she said , `` i 'll see you guys in two weeks -- but i need to see you next week , sir . '' ( laughter ) we have the data to know what makes a great counselor . we know that if you text the words `` numbs '' and `` sleeve , '' there 's a 99 percent match for cutting . we know that if you text in the words `` mg '' and `` rubber band , '' there 's a 99 percent match for substance abuse . and we know that if you text in `` sex , '' `` oral '' and `` mormon , '' you 're questioning if you 're gay . now that 's interesting information that a counselor could figure out but that algorithm in our hands means that an automatic pop-up says , `` 99 percent match for cutting -- try asking one of these questions '' to prompt the counselor . or `` 99 percent match for substance abuse , here are three drug clinics near the texter . '' it makes us more accurate . on the day that robin williams committed suicide , people flooded hotlines all over this country . it was sad to see an icon , a funnyman , commit suicide , and there were three hour wait times on every phone hotline in the country . we had a spike in volume also . the difference was if you text us , `` i want to die , '' or `` i want to kill myself , '' the algorithm reads that , you 're code orange , and you become number one in the queue . so we can handle severity , not chronological . ( applause ) this data is also making the world better because i 'm sitting on the world 's first map of real-time crises . think about it : those 6.5 million messages , auto-tagging through natural language processes , all of these data points -- i can tell you that the worst day of the week for eating disorders : monday . the worst time of day for substance abuse : 5am . and that montana is a beautiful place to visit but you do not want to live there , because it is the number one state for suicidal ideation . and we 've made this data public and free and open . we 've pulled all the personally identifiable information . and it 's in a place called crisistrends.org . because i want schools to be able to see that monday is the worst day for eating disorders , so that they can plan meals and guidance counselors to be there on mondays . and i want families to see that substance abuse questions spike at 5am . i want somebody to take care of those native american reservations in montana . ( applause ) data , evidence makes policy , research , journalism , policing , school boards -- everything better . i do n't think of myself as a mental health activist . i think of myself as a national health activist . i get really excited about this data , i 'm a little nerdy . yeah , that sounded too girly . i 'm nerdy . ( laughter ) i love data . and the only difference really between me and those people in hoodies down the road with their fat-funded companies , is that i 'm not inspired by helping you find chinese food at 2am in dallas , or helping you touch your wrist and get a car immediately , or swipe right and get laid . i 'm inspired -- ( laughter , applause ) i want to use tech and data to make the world a better place . i want to use it to help that girl , who texted in about being raped by her father . because the truth is we never heard from her again . and i hope that she is somewhere safe and healthy , and i hope that she sees this talk and she knows that her desperation and her courage inspired the creation of crisis text line and inspires me every freaking day . ( applause )
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ok -- ( applause ) but there 's one weird side effect . every time we send out a text message , we get back a few dozen text messages having nothing to do with peanut butter or hunger or senior citizens -- but text messages about being bullied , text messages about being addicted to pot . and the worst message we ever got said exactly this : `` he wo n't stop raping me .
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when might it be more likely that someone sends a text to an anonymous tip line rather than making a phone call or reporting something in person ?
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the city sky is , frankly , rather boring . if you look up at the patches of murk between buildings , you might be able to pick out the big dipper , or perhaps , orion 's belt . but hold on . look at that murky patch again and hold our your thumb . how many stars do you think are behind it ? ten , twenty ? guess again . if you looked at that thumbnail-sized patch of sky with the hubble space telescope , instead of points of light , you 'd see smudges . these are n't stars . they 're galaxies , just like our milky way . cities of billions of stars , and more than 1,000 of them are hidden behind your thumb . the universe is bigger than you can see from the city , and even bigger than the starry sky you can see from the countryside . this is the universe as astrophysicists see it , with more stars than all the grains of sand on earth . by staring up at the stars at night , you 've taken part in the oldest science in human history . the study of the heavens is older than navigation , agriculture , perhaps even language itself . yet unlike other sciences , astronomy is purely observational . we can not control the parameters of our experiments from lab benches . our best technology can send man to the moon , and probes to the edge of the solar system . but these distances are vanishingly small compared to the yawning gulfs between stars . so how can we know so much about other galaxies , what they 're made of , how many there are , or that they 're even there at all ? well , we can start with the first thing we see when we look up at night : the stars . what we are trying to learn is their properties . what are they made of ? how hot are they ? how massive ? how old ? how far are they from earth ? and believe it or not , we can learn all of these things simply from the light shining in the sky . we can decipher one kind of stellar message by turning starlight into rainbows . when you look at a rainbow on earth , you 're really looking at light from our sun being scattered through water droplets in the atmosphere into all the different wavelengths that make it up . and we study the light from other stars , we can create rainbows on demand using not water droplets , but other specific instruments that disperse light . when we look at the scattered light from our sun , we see something strange : dark lines in our rainbow . these lines are the characteristic fingerprints of atoms . each type of atom in the solar atmosphere soaks up light at specific wavelengths , and the amount of absorption depends on how many of these atoms there are . so by observing how much light is missing at these characteristic wavelengths , we can tell not only what elements are in the sun 's atmosphere , but even their concentrations . and the same idea can be applied to study other stars . make a spectral rainbow , see what 's missing , and figure out which elements are present . bingo . now you know what stars are made of . but we are n't restricted to just the wavelengths that our eyes perceive . consider radio waves . yes , they can bring the billboard top 100 to your car , but they can also travel almost unimpeded through space . because they 've come so far , radio waves can tell us the very early history of the universe , from just a few thousand years after the big bang . we can also study the infrared light , emitted by colder objects , like the gas and dust clouds in space , and the ultraviolet light from the hot stars recently born from those clouds . studying different wavelengths not only gives us a more complete picture of any single object but also different views of the universe . for this reason , astrophysicists use several different kinds of telescopes covering the spectrum from the infrared to the ultraviolet to the x-ray , from giant radio dishes to giant silver mirrors to space satellites , detecting light that would be otherwise blocked by the earth 's atmosphere . astrophysicists do n't just see the billions of stars among the billions of galaxies in the universe . they hear , feel and sense them through many channels , each revealing a different story . but it all begins with light , the kind we can see and the kind we ca n't . want to know the secrets of the universe ? just follow the light .
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and believe it or not , we can learn all of these things simply from the light shining in the sky . we can decipher one kind of stellar message by turning starlight into rainbows . when you look at a rainbow on earth , you 're really looking at light from our sun being scattered through water droplets in the atmosphere into all the different wavelengths that make it up .
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what can be learned by studying stellar spectra ?
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how much can we really know about the universe beyond our galaxy ? the hubble telescope has enabled us to see objects in space as far 13,000,000,000 light years away . but this still does n't give us the answers to all our questions , questions like , `` what is the universe made of ? '' `` which elements are the most abundant ? '' `` does space contain undiscovered forms of matter ? '' `` could there be antimatter stars or galaxies ? '' some of these questions can not be answered solely from visual images , but what if we had messengers bringing us physical data from distant parts of the cosmos , beyond the reach of explorers or satellites ? in a way , we do , and these `` space messengers '' are called cosmic rays . cosmic rays were first discovered in 1912 by victor hess when he set out to explore variations in the atmosphere 's level of radiation , which had been thought to emanate from the earth 's crust . by taking measurements on board a flying balloon during an eclipse , hess demonstrated both that the radiation actually increased at greater altitudes and that the sun could not be its source . the startling conclusion was that it was n't coming from anywhere within the earth 's atmosphere but from outer space . our universe is composed of many astronomical objects . billions of stars of all sizes , black holes , active galactic nuclei , astroids , planets and more . during violent disturbances , such as a large star exploding into a supernova , billions of particles are emitted into space . although they are called rays , cosmic rays consist of these high energy particles rather than the photons that make up light rays . while the light from an explosion travels in a straight line at its famous constant speed , the particles are trapped in extraordinary loops by magnetic shockwaves generated by the explosion . crossing back and forth through these magnetic field lines accelerates them to almost the speed of light before they escape . there are lots of cosmic rays in space , and some of these particles have traveled for billions of years before reaching earth . when they enter our atmosphere , they collide with the molecules there , generating secondary cosmic rays , lighter particles with less energy than the original . most of these are absorbed into the atmosphere , but some are able to reach the ground , even passing through our bodies . at sea level , this radiation is fairly low . but people who spend a lot of time at higher altitudes , such as airline crews , are exposed to much more . what makes cosmic rays useful as messengers is that they carry the traces of their origins . by studying the frequency with which different particles occur , scientists are able to determine the relative abundance of elements , such as hydrogen and helium , within the universe . but cosmic rays may provide even more fascinating information about the fabric of the universe itself . an experiment called the alpha magnetic spectrometer , a.m.s. , has recently been installed on board the international space station , containing several detectors that can separately measure a cosmic ray particle 's velocity , trajectory , radiation , mass and energy , as well as whether the particle is matter or antimatter . while the two are normally indistinguishable , their opposite charges enable them to be detected with the help of a magnet . the alpha magnetic spectrometer is currently measuring 50 million particles per day with information about each particle being sent in real time from the space station to the a.m.s . control room at cern . over the upcoming months and years , it 's expected to yield both amazing and useful information about antimatter , the possible existence of dark matter , and even possible ways to mitigate the effects of cosmic radiation on space travel . as we stay tuned for new discoveries , look to the sky on a clear night , and you may see the international space station , where the alpha magnetic spectrometer receives the tiny messengers that carry cosmic secrets .
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cosmic rays were first discovered in 1912 by victor hess when he set out to explore variations in the atmosphere 's level of radiation , which had been thought to emanate from the earth 's crust . by taking measurements on board a flying balloon during an eclipse , hess demonstrated both that the radiation actually increased at greater altitudes and that the sun could not be its source . the startling conclusion was that it was n't coming from anywhere within the earth 's atmosphere but from outer space .
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in 1912 , by taking measurements on board a flying balloon during an eclipse , victor hess discovered that :
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the human brain is one of the most sophisticated organs in the world , a supercomputer made of billions of neurons that processes and controls all of our senses , thoughts , and actions . but there was something charles darwin found even more impressive : the brain of an ant , which he called one of the most marvelous atoms of matter in the world . if you find it hard to believe that something so tiny could have a complex brain , you 're not alone . in his project to classify and describe all living things , swedish naturalist carl linnaeus assumed insects had no brains at all . he was wrong , but understandably so . insect brains are not only miniscule , but in many respects , they function differently than our own . one of the most noticeable differences is that an insect that loses its head can still walk , scratch itself , breathe , and even fly . this is because while our nervous system works like a monarchy , with the brain calling the shots , the insect nervous system works more like a decentralized federation . many insect activities , like walking or breathing , are coordinated by clusters of neurons , also known as ganglia , along their bodies . together with the brain , these local ganglia form the insect nervous system . while an insect can do a lot with just its local ganglia , the brain is still crucial for its survival . an insect 's brain lets it perceive the world through sight and smell . it also chooses suitable mates , remembers locations of food sources and hives , regulates communication , and even coordinates navigation over huge distances . and this vast diversity of behaviors is controlled by an organ the size of the head of a pin , with less than one million neurons , compared to our 86 billion . but even though the insect brain is organized very differently from ours , there are some striking similarities . for example , most insects have smell detectors on their antennae , similar to those found in human noses . and our primary olfactory brain regions look and function rather similarly , with clusters of neurons activated and deactivated in precise timing to code for specific scents . scientists have been astonished by these similarities because insects and humans are not very closely related . in fact , our last common ancestor was a simple worm-like creature that lived more than 500 million years ago . so how did we end up with such similar brain structures when our evolution took almost entirely different paths ? scientists call this phenomenon convergent evolution . it 's the same principle behind birds , bats , and bees separately evolving wings . similar selective pressures can cause natural selection to favor the same evolutionary strategy in species with vastly different evolutionary pasts . by studying the comparison between insect and human brains , scientists can thus understand which of our brain functions are unique , and which are general solutions to evolutionary problems . but this is not the only reason scientists are fascinated by insect brains . their small size and simplicity makes it easier to understand exactly how neurons work together in the brain . this is also valuable for engineers , who study the insect brain to help design control systems for everything from self-flying airplanes to tiny search-and-rescue roach bots . so , size and complexity are not always the most impressive things . the next time you try to swat a fly , take a moment to marvel at the efficiency of its tiny nervous system as it outsmarts your fancy brain .
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if you find it hard to believe that something so tiny could have a complex brain , you 're not alone . in his project to classify and describe all living things , swedish naturalist carl linnaeus assumed insects had no brains at all . he was wrong , but understandably so .
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which 18th-century naturalist , who formalized our current system of naming organisms , thought that insects didn ’ t have brains ?
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the discovery of the structure of dna was one of the most important scientific achievements in the last century , in human history , in fact . the now-famous double helix is almost synonymous with watson and crick , two of the scientists who won the nobel prize for figuring it out . but there 's another name you may know , too , rosalind franklin . you may have heard that her data supported watson and crick 's brilliant idea , or that she was a plain-dressing , belligerent scientist , which is how watson actually described her in `` the double helix . '' but thanks to franklin 's biographers , who investigated her life and interviewed many people close to her , we now know that that account is far from true , and her scientific contributions have been vastly underplayed . let 's hear the real story . rosalind elsie franklin was born in london in 1920 . she wanted to be a scientist ever since she was a teenager , which was n't a common or easy career path for girls at that time . but she excelled at science anyway . she won a scholarship to cambridge to study chemistry , where she earned her ph.d. , and she later conducted research on the structure of coal that led to better gas masks for the british during world war ii . in 1951 , she joined king 's college to use x-ray techniques to study the structure of dna , then one of the hottest topics in science . franklin upgraded the x-ray lab and got to work shining high-energy x-rays on tiny , wet crystals of dna . but the acadmemic culture at the time was n't very friendly to women , and franklin was isolated from her colleagues . she clashed with maurice wilkins , a labmate who assumed franklin had been hired as his assistant . but franklin kept working , and in 1952 , she obtained photo 51 , the most famous x-ray image of dna . just getting the image took 100 hours , the calculations necessary to analyze it would take a year . meanwhile , the american biologist james watson and the british physicist francis crick were also working on finding dna 's structure . without franklin 's knowledge , wilkins took photo 51 and showed it to watson and crick . instead of calculating the exact position of every atom , they did a quick analysis of franklin 's data and used that to build a few potential structures . eventually , they arrived at the right one . dna is made of two helicoidal strands , one opposite the other with bases in the center like rungs of a ladder . watson and crick published their model in april 1953 . meanwhile , franklin had finished her calculations , come to the same conclusion , and submitted her own manuscript . the journal published the manuscripts together , but put franklin 's last , making it look like her experiments just confirmed watson and crick 's breakthrough instead of inspiring it . but franklin had already stopped working on dna and died of cancer in 1958 , never knowing that watson and crick had seen her photographs . watson , crick , and wilkins won the nobel prize in 1962 for their work on dna . it 's often said that franklin would have been recognized by a nobel prize if only they could be awarded posthumously . and , in fact , it 's possible she could have won twice . her work on the structure of viruses led to a nobel for a colleague in 1982 . it 's time to tell the story of a brave woman who fought sexism in science , and whose work revolutionized medicine , biology , and agriculture . it 's time to honor rosalind elsie franklin , the unsung mother of the double helix .
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the discovery of the structure of dna was one of the most important scientific achievements in the last century , in human history , in fact . the now-famous double helix is almost synonymous with watson and crick , two of the scientists who won the nobel prize for figuring it out .
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explain why it is so important that we know the structure of dna .
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how can you play a rubik 's cube ? not play with it , but play it like a piano ? that question does n't make a lot of sense at first , but an abstract mathematical field called group theory holds the answer , if you 'll bear with me . in math , a group is a particular collection of elements . that might be a set of integers , the face of a rubik 's cube , or anything , so long as they follow four specific rules , or axioms . axiom one : all group operations must be closed or restricted to only group elements . so in our square , for any operation you do , like turn it one way or the other , you 'll still wind up with an element of the group . axiom two : no matter where we put parentheses when we 're doing a single group operation , we still get the same result . in other words , if we turn our square right two times , then right once , that 's the same as once , then twice , or for numbers , one plus two is the same as two plus one . axiom three : for every operation , there 's an element of our group called the identity . when we apply it to any other element in our group , we still get that element . so for both turning the square and adding integers , our identity here is zero , not very exciting . axiom four : every group element has an element called its inverse also in the group . when the two are brought together using the group 's addition operation , they result in the identity element , zero , so they can be thought of as cancelling each other out . so that 's all well and good , but what 's the point of any of it ? well , when we get beyond these basic rules , some interesting properties emerge . for example , let 's expand our square back into a full-fledged rubik 's cube . this is still a group that satisfies all of our axioms , though now with considerably more elements and more operations . we can turn each row and column of each face . each position is called a permutation , and the more elements a group has , the more possible permutations there are . a rubik 's cube has more than 43 quintillion permutations , so trying to solve it randomly is n't going to work so well . however , using group theory we can analyze the cube and determine a sequence of permutations that will result in a solution . and , in fact , that 's exactly what most solvers do , even using a group theory notation indicating turns . and it 's not just good for puzzle solving . group theory is deeply embedded in music , as well . one way to visualize a chord is to write out all twelve musical notes and draw a square within them . we can start on any note , but let 's use c since it 's at the top . the resulting chord is called a diminished seventh chord . now this chord is a group whose elements are these four notes . the operation we can perform on it is to shift the bottom note to the top . in music that 's called an inversion , and it 's the equivalent of addition from earlier . each inversion changes the sound of the chord , but it never stops being a c diminished seventh . in other words , it satisfies axiom one . composers use inversions to manipulate a sequence of chords and avoid a blocky , awkward sounding progression . on a musical staff , an inversion looks like this . but we can also overlay it onto our square and get this . so , if you were to cover your entire rubik 's cube with notes such that every face of the solved cube is a harmonious chord , you could express the solution as a chord progression that gradually moves from discordance to harmony and play the rubik 's cube , if that 's your thing .
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we can start on any note , but let 's use c since it 's at the top . the resulting chord is called a diminished seventh chord . now this chord is a group whose elements are these four notes .
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a ( n ) _____ chord is a chord that has been rearranged but contains the same notes
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in 1977 , the physicist edward purcell calculated that if you push a bacteria and then let go , it will stop in about a millionth of a second . in that time , it will have traveled less than the width of a single atom . the same holds true for a sperm and many other microbes . it all has to do with being really small . microscopic creatures inhabit a world alien to us , where making it through an inch of water is an incredible endeavor . but why does size matter so much for a swimmer ? what makes the world of a sperm so fundamentally different from that of a sperm whale ? to find out , we need to dive into the physics of fluids . here 's a way to think about it . imagine you are swimming in a pool . it 's you and a whole bunch of water molecules . water molecules outnumber you a thousand trillion trillion to one . so , pushing past them with your gigantic body is easy , but if you were really small , say you were about the size of a water molecule , all of a sudden , it 's like you 're swimming in a pool of people . rather than simply swishing by all the teeny , tiny molecules , now every single water molecule is like another person you have to push past to get anywhere . in 1883 , the physicist osborne reynolds figured out that there is one simple number that can predict how a fluid will behave . it 's called the reynolds number , and it depends on simple properties like the size of the swimmer , its speed , the density of the fluid , and the stickiness , or the viscosity , of the fluid . what this means is that creatures of very different sizes inhabit vastly different worlds . for example , because of its huge size , a sperm whale inhabits the large reynolds number world . if it flaps its tail once , it can coast ahead for an incredible distance . meanwhile , sperm live in a low reynolds number world . if a sperm were to stop flapping its tail , it would n't even coast past a single atom . to imagine what it would feel like to be a sperm , you need to bring yourself down to its reynolds number . picture yourself in a tub of molasses with your arms moving about as slow as the minute hand of a clock , and you 'd have a pretty good idea of what a sperm is up against . so , how do microbes manage to get anywhere ? well , many do n't bother swimming at all . they just let the food drift to them . this is somewhat like a lazy cow that waits for the grass under its mouth to grow back . but many microbes do swim , and this is where those incredible adaptations come in . one trick they can use is to deform the shape of their paddle . by cleverly flexing their paddle to create more drag on the power stroke than on the recovery stroke , single-celled organisms like paramecia manage to inch their way through the crowd of water molecules . but there 's an even more ingenious solution arrived at by bacteria and sperm . instead of wagging their paddles back and forth , they wind them like a cork screw . just as a cork screw on a wine bottle converts winding motion into forward motion , these tiny creatures spin their helical tails to push themselves forward in a world where water feels as thick as cork . other strategies are even stranger . some bacteria take batman 's approach . they use grappling hooks to pull themselves along . they can even use this grappling hook like a sling shot and fling themselves forward . others use chemical engineering . h. pylori lives only in the slimy , acidic mucus inside our stomachs . it releases a chemical that thins out the surrounding mucus , allowing it to glide through slime . maybe it 's no surprise that these guys are also responsible for stomach ulcers . so , when you look really closely at our bodies and the world around us , you can see all sorts of tiny creatures finding clever ways to get around in a sticky situation . without these adaptations , bacteria would never find their hosts , and sperms would never make it to their eggs , which means you would never get stomach ulcers , but you would also never be born in the first place . ( pop )
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microscopic creatures inhabit a world alien to us , where making it through an inch of water is an incredible endeavor . but why does size matter so much for a swimmer ? what makes the world of a sperm so fundamentally different from that of a sperm whale ?
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if a human swimmer were to somehow shrink down to the size of a microbe , what difficulties would they face in getting around ? what strategies could this tiny swimmer adopt to swim more effectively ?
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they say the pen is mightier than the sword , and authorities have often agreed . from outlawed religious tracts and revolutionary manifestos to censored and burned books , we know the potential power of words to overturn the social order . but as strange as it may seem , some numbers have also been considered dangerous enough to ban . our distant ancestors long counted objects using simple tally marks . but as they developed agriculture and began living together in larger groups , this was no longer enough . as numbers grew more complex , people began not just using them , but thinking about what they are and how they work . and by 600 b.c.e . in ancient greece , the study of numbers was well-developed . the mathematician pythagoras and his school of followers found numerical patterns in shapes , music , and the stars . for them , mathematics held the deepest secrets of the universe . but one pythagorean named hippasus discovered something disturbing . some quantities , like the diagonal of a square with sides of length one could n't be expressed by any combination of whole numbers or fractions , no matter how small . these numbers , which we call irrational numbers , were perceived as a threat to the pythagorean 's notion of a perfect universe . they imagined a reality that could be described with rational , numerical patterns . historians write that hippasus was exhiled for publicizing his findings , while legends claim he was drowned as punishment from the gods . while irrational numbers upset philosophers , later mathematical inventions would draw attention from political and religious authorities , as well . in the middle ages , while europe was still using roman numerals , other cultures had developed positional systems that included a symbol for zero . when arab travelers brought this system to the bustling maritime cities of italy , its advantages for merchants and bankers was clear . but the authorities were more wary . hindu-arabic numerals were considered easier to forge or alter , especially since they were less familiar to customers than to merchants . and the concept of zero opened the door to negative numbers and the recording of debt at a time when moneylending was regarded with suspicion . in the 13th century , florence banned the use of hindu-arabic numerals for record keeping . and though they soon proved too useful to ignore , controversies over zero and negative numbers continued for a long time . negative numbers were dismissed as absurd well into the 19th century . and prominent mathematicians , like gerolamo cardano , avoided using zero , even though it would have made it much easier to find solutions to cubic and the quartic equations . even today it 's illegal to use some numbers for different reasons . some are banned because of what they represent . for example , governments have prohibited the display of numbers that have symbolic meaning , such as the date of a revolution or connections to oppositional political figures or parties . other numbers are potentially illegal because of the information they carry . just about any information , whether text , image , video , or executable programs can be translated into a string of numbers . but this means that protected information , whether copyrights , proprietary materials , or state secrets can also be represented as numbers , so possessing or publishing these numbers may be treated as a criminal offense . this idea gathered attention in 2001 when code that could be used to decrypt dvds was widely shared and distributed in the form of a large prime number . the idea of illegal numbers may sound absurd , but like words , written numbers are a way of expressing concepts and information . and in a world where calculations and algorithms shape more and more of our lives , the mathematician 's pencil grows stronger by the day .
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they say the pen is mightier than the sword , and authorities have often agreed . from outlawed religious tracts and revolutionary manifestos to censored and burned books , we know the potential power of words to overturn the social order .
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who were the pythagoreans ?
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so krypton is one of the noble gases , it ’ s not very reactive but it does react with the element fluorine . jim turner , who was my supervisor when i did my doctorate , was the first person to discover that fluorine could react with krypton but even that reaction requires quite bright lights to break the bond between the fluorine atoms to get them to react . but krypton can also be used in lasers when mixtures of krypton and of fluorine-containing compound can be used to generate very bright pulses or intense pulses of ultraviolet light . some years ago we had a professor here who bought a really big krypton-fluoride laser and when he switched it on and the beam hit the wall it burnt a hole right through the wall so he knew where to make the hole to get his beam into the next lab .
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jim turner , who was my supervisor when i did my doctorate , was the first person to discover that fluorine could react with krypton but even that reaction requires quite bright lights to break the bond between the fluorine atoms to get them to react . but krypton can also be used in lasers when mixtures of krypton and of fluorine-containing compound can be used to generate very bright pulses or intense pulses of ultraviolet light . some years ago we had a professor here who bought a really big krypton-fluoride laser and when he switched it on and the beam hit the wall it burnt a hole right through the wall so he knew where to make the hole to get his beam into the next lab .
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several years ago a professor at the university of nottingham accidentally burnt a hole in the wall of his lab with a krypton-fluoride laser . these lasers radiate energy near the ultraviolet portion of the spectrum . what is the wavelength that a kr-f laser radiates at ?
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translator : andrea mcdonough reviewer : bedirhan cinar fourth and nineteen , folks , they 've got ta have a play as time 's ticking away because they 've got to stay in this ball game , they 've got to win . they come out lined up in the empty set , three receivers to the right , two to the left . defense looks like they 're gon na to man up with no safety . this is the exact offensive match-up that they want : the best receiver lined up against the linebacker . quarterback steps back to receive the ball , five yards deep in the gun . he takes a snap , drops three steps , he plants his back foot , he 's looking for an opening . there 's a blitz coming off the edge ! he steps up to avoid the rush . he 's looking down field . he 's got the inside receiver making a cut . he 's got a step on the linebacker . quarterback has a beat on it . he lets the ball go , it 's in the air ! receiver is out in front of the defender . he 's got it beat ! he 's out in front , racing for the ball ! it 's coming down ! he cradles it at the fifteen ! he 's at the ten , five ! touchdown ! unbelievable play ! now , wait a minute . of course , it 's believable , it 's physics , specifically the differences between scalars and vectors . so , let 's just see that replay . `` quarterback steps back to receive the ball , five yards deep in the gun . '' stop . see , measurements are defined as two different quantities . scalars are measurements with only numbers , and vectors are measurements with direction . for example , when that quarterback takes the snap , he 's five yards away , but from where ? back from the line of scrimmage , so the five yards by itself is a scalar quantity . when you add a direction , like five yards deep , it becomes a vector quantity . five yards - scalar , five yards deep - vector . ok , go ahead . `` he takes a snap , drops three steps . he plants his back foot , he 's looking for an opening . there 's a blitz coming off the edge ! he steps up to avoid the rush . '' whoa ! here 's a difference between distance and displacement . distance is a measurement without identifying where you moved . it 's a scalar quantity . when the quarterback makes a three-step drop , he moves about three yards back . when he moves about another three yards forward , when he steps up into the pocket , so that quarterback moves a total distance of six yards . that 's a distance , that 's a scalar . now , displacement is a vector quantity , describing about how far out of place the object is . so the quarterback dropped back three yards and then moved back forward three yards , he 's in the exact same place where he started . so , his displacement is zero yards . distance - six yards , displacement - zero yards . so , let 's look at what happened next . `` quarterback has a beat on it , he let 's the ball go ! it 's in the air ! receiver is out in front of the defender . '' stop . so , here 's speed and velocity , but let 's just do one thing at a time . so , speed is measurement without direction , it 's a scalar quantity . velocity is a vector quantity . it is that object 's speed , but with a direction of motion . so the receiver accelerates away , gaining both speed and distance . this takes the receiver 5 seconds to run those 50 yards . so his average speed , in any given time , is 10 yards/second . the linebacker tries to keep up , but his overall speed is slower , he only goes 35 yards in those 5 seconds , so his average speed is only 7 yards/second . they 're both traveling in a forward direction , so their velocity is also positive . you ca n't go from resting to your peak speed immediately . you 've got to build up to it . this is acceleration . at first the linebacker can keep up with that receiver , but eventually the faster receiver pulls away . that 's acceleration , the change in speed over time . acceleration is a vector quantity . it describes a rate at which an object changes velocity . like velocity , acceleration is a vector . it happens in a direction . so let 's just look at that play just one more time . `` quarterback steps back to receive the ball , five yards deep in the gun . '' vector ! `` he takes a snap , drops three steps , he plants his back foot . he 's looking for an opening . there 's a blitz coming off the edge ! he steps up to avoid the rush . '' displacement ! `` he 's got the inside receiver making a cut . he 's got a step on the linebacker . the quarterback has a beat on it . he let 's the ball go ! it 's in the air ! receiver is out in front of the defender ! '' velocity ! `` he 's got it beat ! he 's out in front , racing for the ball ! it 's coming down ! he cradles it at the fifteen , he 's at the ten , five ! '' acceleration ! `` touchdown ! unbelievable play ! that was a great play as time expired , resulting in the touchdown and ultimately the win and pure effort . '' and pure science .
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this takes the receiver 5 seconds to run those 50 yards . so his average speed , in any given time , is 10 yards/second . the linebacker tries to keep up , but his overall speed is slower , he only goes 35 yards in those 5 seconds , so his average speed is only 7 yards/second .
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you drive 200 miles in 3 hours before stopping for 30 minutes for lunch and gas . after lunch you travel 150 miles in an hour and a half . what was your average speed for the trip ?
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translator : andrea mcdonough reviewer : jessica ruby we often hear that studying literature involves finding a deeper meaning to a text . when writing about literary works , we 're expected to mentally dive below the surface in order to come back up with big ideas . but you may find yourself looking at the flat page of a book , wondering how deep it can really go ? how do we reach those ideas that turn into great essays ? well , there are two crucial thinking steps that can lead us in the right direction : practicing insight and acknowledging complexity . insight is the ability to arrive at an intuitive understanding of a big idea using only small clues to get there . if you 're practicing insight , you 'll able to use observations about character behavior to figure out their true emotions and motivations . pay attention to little things because they add up to what is really meaningful . for example , if you consider a character like mr. darcy from < i > pride and prejudice < /i > , who openly declares his dislike for miss lizzy bennet , you might , at first , assume he 's just a mean guy . but , using your powers of insight , you 're noticing other smaller things - how darcy 's eyes linger on lizzy 's face and how he seems all flustered when she 's around . add to the mix your knowledge that mr. darcy is in a much higher social class than lizzy , and your sense of insight should be telling you that there 's something more here . in this case , it will tell you that darcy 's surface behavior is in conflict with his true feelings of attraction because the difference in wealth between himself and lizzy makes him feel that it 'll never work . thinking about all those small clues gives us insight about some of the big , abstract ideas within the novel that we can approach in an essay : appearances versus reality , the power of wealth and social stratification , and the unpredictable nature of love and attraction . look at that ! deeper meaning . the second step to a sophisticated analysis is acknowledging complexity . let 's face it . in both life and literature , situations are complicated due to social forces like relationships , moral codes , personal desires , and power structures . this means that there are , at any given time , multiple factors that shape what is true . in order to acknowledge complexity in your writing , refrain from making broad generalizations about a text or establishing quick , simple judgements about a character . explore each facet of your subject carefully and make sure to consider multiple influences on events . explain the tension of multiple forces that create the story . for example , a basic analysis of toni morrison 's < i > beloved < i > , where the protagonist has killed her own child rather than allow her to grow up in slavery , might sound like this , `` sethe murdered her own daughter . this act was wrong , and causes the ghost of the child to haunt her throughout the novel . '' these observations are simplistic . they do n't acknowledge all the different forces that contribute to what the character has done . try something like this instead , `` a culture of slavery disturbs the ability to determine what is morally right . sethe 's past experiences with violence reinforce the fear she has for her child 's fate , and transform the murder into a protective act . as the novel progresses , sethe is haunted both by the angry spirit of her daughter and by the memories of everything else slavery took from her . '' here , we see those influential forces at work , and we 've shown off our ability to understand the complicated nature of the human experience , which , again , allows us to access those big ideas that reveal the deeper meaning of a story , ideas , in this case , like the parameters of maternal instinct , the consequences of injustice , and the question of whether or not ethics can even exist in a corrupted moral system . it 's impossible to sit down and write an amazing essay about literature without first thinking about it . before you hit the keys , go back to the text and fish out the small moments , the complicated moments in the story . line them up in your mind , practice insight , acknowledge complexity , arrive at some big ideas . before you know it , the deeper meaning will be close at hand .
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well , there are two crucial thinking steps that can lead us in the right direction : practicing insight and acknowledging complexity . insight is the ability to arrive at an intuitive understanding of a big idea using only small clues to get there . if you 're practicing insight , you 'll able to use observations about character behavior to figure out their true emotions and motivations . pay attention to little things because they add up to what is really meaningful .
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think about the most recent literary text you ’ ve studied . give some examples of small details that you noticed about one of the characters . then , apply your powers of insight to come to some conclusions about that character ’ s motivations based on those clues .
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just for a moment , focus on your breath . in slowly . out slowly . in slowly . out . the same pattern repeats within every one of us and consider your pulse . the beat is built into the very fabric of our being . simply put , we 're creatures of rhythm and repetition . it 's central to our experience , rhythm and repetition , rhythm and repetition . on , and in , and on , and out . and we delight in those aspects everyday , in the rhythm of a song , the beat of the drum , the nod of your head , or in the repetition of soup cans , the rows of an orchard , the artistry of petals . pattern can be pleasure . in language , rhythm and repetition are often used as the building blocks for poetry . there 's the rhythm of language , created by syllables and their emphasis , such as , `` so long as men can breathe or eyes can see . '' and there 's the repetition of language at multiple levels : the repetition of letters , `` so long lives this and this gives life to thee , '' of sounds , `` breathe , '' `` see , '' `` thee , '' and of words . with so many uses , repetition is one of the poet 's most malleable and reliable tools . it can lift or lull the listener , amplify or diminish the line , unify or diversify ideas . in fact , even rhythm itself , a repeated pattern of stressed syllables , is a form of repetition . yet for all its varied uses , too much repetition can backfire . imagine writing the same sentence on the blackboard twenty times , again , and again , and again , and again , or imagine a young child clamoring for her mother 's attention , `` mom , mom , mommy , mom , mom . '' not exactly what we might call poetry . so what is poetic repetition , and why does it work ? possibly most familiar is rhyme , the repetition of like sounds in word endings . as with shakespeare 's example , we often encounter rhyme at the ends of lines . repetition in this way creates an expectation . we begin to listen for the repetition of those similar sounds . when we hear them , the found pattern is pleasurable . like finding waldo in the visual chaos , we hear the echo in the oral chatter . yet , rhyme need not surface solely at a line 's end . notice the strong `` i '' sound in , `` so long lives this and this gives life to thee . '' this repetition of vowel sounds is called assonance and can also be heard in eminem 's `` lose yourself . '' notice how the `` e '' and `` o '' sounds repeat both within in and at the end of each line : `` oh , there goes gravity , oh , there goes rabbit , he choked , he so mad but he wo n't give up that easy , no , he wo n't have it , he knows his whole back 's to these ropes . '' the alternating assonance creates its own rhythm , and invites us to try our own voices in echoing it . similarly , consonance is the repetition of like consonant sounds , such as the `` l '' and `` th '' in , `` so long lives this and this gives life to thee . '' in fact , this type of specific consonance , which occurs at the beginning of words may be familiar to you already . it 's called alliteration , or front rhyme . great examples include tongue twisters . betty bought some butter but the butter was bitter so betty bought some better butter to make the bitter butter better . here , the pleasure in pattern is apparent as we trip over the consonance both within words and at their start . yet tongue twisters also reflect the need for variation in poetic repetition . while challenging to say , they 're seen by some as lesser imitations of poetry , or gimmicky because they hammer so heavily on the same sounds , closer to that blackboard-style of repetition . ultimately , this is the poet 's balancing act , learning when to repeat and when to riff , when to satisfy expectations , and when to thwart them , and in that balance , it may be enough to remember we all live in a world of wild variation and carry with us our own breath and beat , our own repetition wherever we go .
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the beat is built into the very fabric of our being . simply put , we 're creatures of rhythm and repetition . it 's central to our experience , rhythm and repetition , rhythm and repetition . on , and in , and on , and out .
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have you noticed some lines/lyrics are more fun to sing along with than others ? does repetition of sound appear more or less in those lines/lyrics ? if so , which kinds of repetition do they use ?
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which is the hardest word to translate in this sentence ? `` know '' is easy to translate . `` pep rally '' does n't have a direct analog in a lot of languages and cultures , but can be approximated . but the hardest word there is actually one of the smallest : `` you . '' as simple as it seems , it 's often impossible to accurately translate `` you '' without knowing a lot more about the situation where it 's being said . to start with , how familiar are you with the person you 're talking to ? many cultures have different levels of formality . a close friend , someone much older or much younger , a stranger , a boss . these all may be slightly different `` you 's . '' in many languages , the pronoun reflects these differences through what 's known as the t–v distinction . in french , for example , you would say `` tu '' when talking to your friend at school , but `` vous '' when addressing your teacher . even english once had something similar . remember the old-timey `` thou ? '' ironically , it was actually the informal pronoun for people you 're close with , while `` you '' was the formal and polite version . that distinction was lost when the english decided to just be polite all the time . but the difficulty in translating `` you '' does n't end there . in languages like hausa or korana , the `` you '' form depends on the listener 's gender . in many more , it depends on whether they are one or many , such as with german `` du '' or `` ihr . '' even in english , some dialects use words like `` y'all '' or `` youse '' the same way . some plural forms , like the french `` vous '' and russian `` вы '' are also used for a single person to show that the addressee is that much more important , much like the royal `` we . '' and a few languages even have a specific form for addressing exactly two people , like slovenian `` vidva . '' if that was n't complicated enough , formality , number , and gender can all come into play at the same time . in spanish , `` tú '' is unisex informal singular , `` usted '' is unisex formal singular , `` vosotros '' is masculine informal plural , `` vosotras '' is feminine informal plural , and `` ustedes '' is the unisex formal plural . phew ! after all that , it may come as a relief that some languages often leave out the second person pronoun . in languages like romanian and portuguese , the pronoun can be dropped from sentences because it 's clearly implied by the way the verbs are conjugated . and in languages like korean , thai , and chinese , pronouns can be dropped without any grammatical hints . speakers often would rather have the listener guess the pronoun from context than use the wrong one and risk being seen as rude . so if you 're ever working as a translator and come across this sentence without any context : `` you and you , no , not you , you , your job is to translate 'you ' for yourselves '' ... well , good luck . and to the volunteer community who will be translating this video into multiple languages : sorry about that !
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if that was n't complicated enough , formality , number , and gender can all come into play at the same time . in spanish , `` tú '' is unisex informal singular , `` usted '' is unisex formal singular , `` vosotros '' is masculine informal plural , `` vosotras '' is feminine informal plural , and `` ustedes '' is the unisex formal plural . phew !
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even though your language may not have a clear distinction between a formal and an informal “ you , ” this doesn ’ t mean that you don ’ t speak differently to friends and family than you speak to strangers and superiors . what are the ways you change the way you talk based on how familiar you are with the other person ?
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if you spent any time on earth you might have noticed that humans are not the most rational creatures we make decisions based mostly on emotions instead of facts and a lot of times we 're guided by tribal instinct part of the problem is that the human brain evolved to help us survive and not necessarily to help us be factually accurate so we often respond better to social and tribal dynamics than to intellectual analysis for example if someone 's tribe believes that obama is a secret muslim born in kenya that person probably thinks the hard proof of his us birth certificate is fake that conclusion is neither rational nor accurate but from a tribal perspective it makes sense it 's safer to agree with your tribe and stay united ideologically even if you 're wrong about the facts than to disagree and isolate yourself another part of the problem is that our brain is constantly protecting our worldview and sense of identity so when our worldview is challenged that same part of the brain that processes physical danger gets activated this is why people sometimes react so aggressively to information that proves them wrong and this is why it 's often so hard to have an intelligent political debate several studies have also shown that there is a backfire effect that happens when people encounter facts that contradict their current beliefs they actually become more convinced of their original ideas so fighting ignorant with facts is like fighting a grease fire with water it seems like it should work but it actually just makes the whole thing work lastly there 's the problem of lack of empathy several studies have found that when humans are divided into groups of any kind we instinctively become less and pathetic to members of other groups that means that for survivals sake we men instinctively empathize less with other races other nationalities and even though their sports teams this instinctive the humanization of other groups is what makes things like slavery and genocide possible in our society so what can you do if you want someone to consider factual information that clashes with their beliefs first you have to prevent their brain from seeing you as a personal threat so look for ways to identify the person as part of your tribe and you as part of theirs hey we 're part of the same family hey we 're both parents hey we both still play pokemon go whatever anything that communicates that you 're part of the same that 's the first step second consider the possibility that you may be wrong maybe the facts are not on your side in which case admitting it will help you model to the other person that it 's okay to be wrong i understand that none of this is easy or smooth but if we want to continue to function as a stable society we have to learn to get past our own natural biases only when that happens we will be able to move forward towards a better future
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if you spent any time on earth you might have noticed that humans are not the most rational creatures we make decisions based mostly on emotions instead of facts and a lot of times we 're guided by tribal instinct part of the problem is that the human brain evolved to help us survive and not necessarily to help us be factually accurate so we often respond better to social and tribal dynamics than to intellectual analysis for example if someone 's tribe believes that obama is a secret muslim born in kenya that person probably thinks the hard proof of his us birth certificate is fake that conclusion is neither rational nor accurate but from a tribal perspective it makes sense it 's safer to agree with your tribe and stay united ideologically even if you 're wrong about the facts than to disagree and isolate yourself another part of the problem is that our brain is constantly protecting our worldview and sense of identity so when our worldview is challenged that same part of the brain that processes physical danger gets activated this is why people sometimes react so aggressively to information that proves them wrong and this is why it 's often so hard to have an intelligent political debate several studies have also shown that there is a backfire effect that happens when people encounter facts that contradict their current beliefs they actually become more convinced of their original ideas so fighting ignorant with facts is like fighting a grease fire with water it seems like it should work but it actually just makes the whole thing work lastly there 's the problem of lack of empathy several studies have found that when humans are divided into groups of any kind we instinctively become less and pathetic to members of other groups that means that for survivals sake we men instinctively empathize less with other races other nationalities and even though their sports teams this instinctive the humanization of other groups is what makes things like slavery and genocide possible in our society so what can you do if you want someone to consider factual information that clashes with their beliefs first you have to prevent their brain from seeing you as a personal threat so look for ways to identify the person as part of your tribe and you as part of theirs hey we 're part of the same family hey we 're both parents hey we both still play pokemon go whatever anything that communicates that you 're part of the same that 's the first step second consider the possibility that you may be wrong maybe the facts are not on your side in which case admitting it will help you model to the other person that it 's okay to be wrong i understand that none of this is easy or smooth but if we want to continue to function as a stable society we have to learn to get past our own natural biases only when that happens we will be able to move forward towards a better future
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what two tips does the video offer if you want someone to consider factual information that clashes with their beliefs ?
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the biggest kidney stone on record weighed more than a kilogram and was 17 centimeters in diameter . the patient did n't actually swallow a stone the size of a coconut . kidney stones form inside the body , but unfortunately , they 're extremely painful to get out . a kidney stone is a hard mass of crystals that can form in the kidneys , ureters , bladder , or urethra . urine contains compounds that consist of calcium , sodium , potassium , oxalate , uric acid , and phosphate . if the levels of these particles get too high , or if urine becomes too acidic or basic , the particles can clump together and crystallize . unless the problem is addressed , the crystals will gradually grow over a few weeks , months , or even years , forming a detectable stone . calcium oxalate is the most common type of crystal to form this way , and accounts for about 80 % of kidney stones . less common kidney stones are made of calcium phosphate , or uric acid . a slightly different type of stone made of the minerals magnesium ammonium phosphate , or struvite , can be caused by bacterial infection . and even rarer stones can result from genetic disorders or certain medications . a kidney stone can go undetected until it starts to move . when a stone travels through the kidney and into the ureter , its sharp edges scratch the walls of the urinary tract . nerve endings embedded in this tissue transmit excruciating pain signals through the nervous system . and the scratches can send blood flowing into the urine . this can be accompanied by symptoms of nausea , vomiting , and a burning sensation while urinating . if a stone gets big enough to actually block the flow of urine , it can create an infection , or back flow , and damage the kidneys themselves . but most kidney stones do n't become this serious , or even require invasive treatment . masses less than five millimeters in diameter will usually pass out of the body on their own . a doctor will often simply recommend drinking large amounts of water to help speed the process along , and maybe taking some pain killers . if the stone is slightly larger , medications like alpha blockers can help by relaxing the muscles in the ureter and making it easier for the stone to get through . another medication called potassium citrate can help dissolve the stones by creating a less acidic urine . for medium-sized stones up to about ten millimeters , one option is pulverizing them with soundwaves . extracorporeal shock wave lithotripsy uses high-intensity pulses of focused ultrasonic energy aimed directly at the stone . the pulses create vibrations inside the stone itself and small bubbles jostle it . these combined forces crush the stone into smaller pieces that can pass out of the body more easily . but zapping a stone with sound does n't work as well if it 's simply too big . so sometimes , more invasive treatments are necessary . a rigid tube called a stent can be placed in the ureter to expand it . optical fibers can deliver laser pulses to break up the stone . stones can also be surgically removed through an incision in the patient 's back or groin . what about just avoiding kidney stones in the first place ? for people prone to them , their doctor may recommend drinking plenty of water , which dilutes the calcium oxalate and other compounds that eventually build up into painful stones . foods like potato chips , spinach , rhubarb , and beets are high in oxalate , so doctors might advise limiting them . even though calcium is often found in stones , calcium in foods and beverages can actually help by binding to oxalate in the digestive tract before it can be absorbed and reach the kidneys . if you do end up with a kidney stone , you 're not alone . data suggests that rates are rising , but that world record probably wo n't be broken any time soon .
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and even rarer stones can result from genetic disorders or certain medications . a kidney stone can go undetected until it starts to move . when a stone travels through the kidney and into the ureter , its sharp edges scratch the walls of the urinary tract .
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what are the precipitating factors of kidney stone formation ?
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the naming of clouds on a cold december evening in 1802 , a nervous young man named luke howard stood before the assembled members of a london science club about to give a lecture that would change his life and go on to change humanity 's understanding of the skies . luke howard was a pharmacist by profession , but he was a meteorologist by inclination , having been obsessed by clouds and weather since childhood . as a school boy , he spent hours staring out of the classroom window , gazing at the passing clouds . like everyone else at the time , he had no idea how clouds formed , or how they stayed aloft . but he enjoyed observing their endless transformations . by his own admission , luke paid little attention to his lessons , but fortunately for the future of meteorology , he managed to pick up a good knowledge of latin . compared to the other natural sciences , meteorology , the study of weather , was a late developer , mainly because weather is elusive . you ca n't snap off a piece of rainbow or a section of cloud for convenient study . you can , of course , collect rain water in calibrated containers , but all you really end up with are buckets of water . understanding clouds required a different approach , which is where luke howard 's idea came in . his simple insight based on years of observation was that clouds have many individual shapes but they have few basic forms . in fact , all clouds belong to one of three principle types to which howard gave the names : cirrus , latin for tendril or hair , cumulus , heap or pile , and stratus , layer or sheet . but that was n't the clever part . clouds are constantly changing , merging , rising , falling , and spreading throughout the atmosphere , rarely maintaining the same shapes for more than a few minutes . any successful naming system had to accommodate this essential instability , as howard realized . so , in addition to the three main cloud types , he introduced a series of intermediate and compound types as a way of including the regular transitions that occur among clouds . a high , whispy cirrus cloud that descended and spread into a sheet was named cirrostratus , while groups of fluffy cumulus clouds that joined up and spread were named stratocumulus . howard identified seven cloud types , but these have since been expanded to ten , cloud nine being the towering cumulonimbus thunder cloud , which is probably why being on cloud nine means to be on top of the world . howard 's classification had an immediate international impact . the german poet and scientist j.w . von goethe wrote a series of poems in praise of howard 's clouds , which ended with the memorable lines , `` as clouds ascend , are folded , scatter , fall , let the world think of thee who taught it all , '' while percy shelley also wrote a poem `` the cloud , '' in which each of howard 's seven cloud types was characterized in turn . but perhaps the most impressive response to the naming of clouds was by the painter john constable , who spent two summers on hampstead heath painting clouds in the open air . once they had been named and classified , clouds became easier to understand as the visible signs of otherwise invisible atmospheric processes . clouds write a kind of journal on the sky that allows us to understand the circulating patterns of weather and climate . perhaps the most important breakthrough in understanding clouds was realizing that they are subject to the same physical laws as everything else on earth . clouds , for example , do not float , but fall slowly under the influence of gravity . some of them stay aloft due to upward convection from the sun-heated ground , but most are in a state of slow , balletic descent . `` clouds are the patron goddesses of idle fellows , '' as the greek dramatist aristophanes wrote in 420 b.c . and nephology , the study of clouds , remains a daydreamer 's science , aptly founded by a thoughtful young man whose favorite activity was staring out of the window at the sky .
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the naming of clouds on a cold december evening in 1802 , a nervous young man named luke howard stood before the assembled members of a london science club about to give a lecture that would change his life and go on to change humanity 's understanding of the skies . luke howard was a pharmacist by profession , but he was a meteorologist by inclination , having been obsessed by clouds and weather since childhood . as a school boy , he spent hours staring out of the classroom window , gazing at the passing clouds .
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luke howard 's profession was :
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muhammad ali spent years training to become the greatest boxer the world had ever seen , but only moments to create the shortest poem . ali captivated harvard 's graduating class in 1975 with his message of unity and friendship . when he finished , the audience wanted more . they wanted a poem . ali delivered what is considered the shortest poem ever . `` me , we . '' or is it `` me , weeee '' ? no one 's really sure . regardless , if these two words are a poem , then what exactly makes a poem a poem ? poets themselves have struggled with this question , often using metaphors to approximate a definition . is a poem a little machine ? a firework ? an echo ? a dream ? poetry generally has certain recognizable characteristics . one - poems emphasize language 's musical qualities . this can be achieved through rhyme , rhythm , and meter , from the sonnets of shakepeare , to the odes of confucius , to the sanskrit vedas . two - poems use condensed language , like literature with all the water wrung out of it . three - poems often feature intense feelings , from rumi 's spiritual poetry to pablo neruda 's `` ode to an onion . '' poetry , like art itself , has a way of challenging simple definitions . while the rhythmic patterns of the earliest poems were a way to remember stories even before the advent of writing , a poem does n't need to be lyrical . reinhard döhl 's “ apfel ” and eugen gomringer 's `` silencio '' toe the line between visual art and poetry . meanwhile , e.e . cummings wrote poems whose shapes were as important as the words themselves , in this case amplifying the sad loneliness of a single leaf falling through space . if the visual nature of poetry faded into the background , perhaps we 'd be left with music , and that 's an area that people love to debate . are songs poems ? many do n't regard songwriters as poets in a literary sense , but lyrics from artists like paul simon , bob dylan , and tupac shakur often hold up even without the music . in rap , poet elements like rhyme , rhythm , and imagery are inseparable from the form . take this lyric from the notorious b.i.g . `` i can hear sweat trickling down your cheek your heartbeat sound like sasquatch feet thundering , shaking the concrete . '' so far , all the examples we 've seen have had line breaks . we can even imagine the two words of ali 's poem organizing in the air - me , we . poetry has a shape that we can usually recognize . its line breaks help readers navigate the rhythms of a poem . but what if those line breaks disappeared ? would it lose its essence as a poem ? maybe not . enter the prose poem . prose poems use vivid images and wordplay but are formatted like paragraphs . when we look at poetry less as a form and more as a concept , we can see the poetic all around us : spiritual hymns , the speeches of orators like martin luther king , jr. , jfk , and winston churchill , and surprising places like social media . in 2010 , journalist joanna smith tweeted updates from the earthquake in haiti . `` was in b-room getting dressed when heard my name . tremor . ran outside through sliding door . all still now . safe . roosters crowing . '' smith uses language in a way that is powerful , direct , and filled with vivid images . compare her language to a haiku , the ancient japanese poetic form that emphasizes bursts of brief intensity with just three lines of five , seven , and five syllables . the waters of poetry run wide and deep . poetry has evolved over time , and perhaps now more than ever , the line between poetry , prose , song , and visual art has blurred . however , one thing has not changed . the word poetry actually began in verb form , coming from the ancient greek poiesis , which means to create . poets , like craftsman , still work with the raw materials of the world to forge new understandings and comment on what it is to be human in a way only humans can . dartmouth researchers tested this idea by asking robots to pen poetry . a panel of judges sorted through stacks of sonnets to see if they could distinguish those made by man and machine . you may be happy to know that while scientists have successfully used artificial intelligence in manufacturing , medicine , and even journalism , poetry is a different story . the robots were caught red-handed 100 % of the time .
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however , one thing has not changed . the word poetry actually began in verb form , coming from the ancient greek poiesis , which means to create . poets , like craftsman , still work with the raw materials of the world to forge new understandings and comment on what it is to be human in a way only humans can .
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the word poetry comes from the greek “ poiesis. ” what does this word mean ?
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each spring , nature lovers eagerly greet the signs that winter is finally coming to an end . as the days grow warmer , the flowers and trees start to bloom , and the world comes alive with the melodious call of birds in search of a new mate . but where have these enchanting sounds been hiding all winter ? for almost 200 species of song birds , their winters have been spent down in the tropical climates of central and south america . while this may sound ideal , it involves one of the most perilous journeys known in the entire animal kingdom . this journey is called migration , and for song birds , this can involve travelling somewhere between a few hundred to almost 7,000 miles in a period of several weeks to four months . birds spend weeks preparing for the intense journey by gorging on large quantities of food , sometimes doubling their weight prior to departure . while flying , birds can lose almost one percent of their body weight an hour , so packing on the pounds is crucial to their survival . however , more than the physical stress , migrating birds are now facing a new source of hardship : landscape change . just imagine you 're the one getting ready to take a trip . you 've packed the car with everything you think you need , fueled up the tank , eaten a huge breakfast , and hit the road . you 've taken this journey before . you know all your favorite rest stops and little back-alley diners to grab a bite . everything is planned out . but just as your fuel gauge starts dipping into the red zone , you pass by what should have been a gas station , except it 's closed . `` not a problem , '' you think , `` the next one ca n't be too far away . '' but then that next station never appears . unfortunately , as you continue on your route , the reality of the situation starts to set in . more and more stations are closed or just erased from your map . all of a sudden , your routine trip has become a desperate search just to find somewhere safe to rest and refuel for the night . this scenario has become the reality for the majority of migrating song birds as human land development continues unchecked . humans are altering important stop-over sites that birds have been using for generations . as migrators pass over the continent , they run a gauntlet of dangers , including pesticide ingestion in rural farmlands , habitat loss in suburban developments , as well as disorientation from light pollution , and even structure collision with tall , reflective glass buildings in cities . of the estimated 20 billion individual birds that comprise the fall population , only about half will return to breed the following spring . almost one billion of these deaths are attributed just to building collisions . with such astounding yearly losses , humans risk more than just the loss of the beautiful colors and songs of birds , they also play an important role in the ecosystem . birds help with insect control , pollination , and disbursing seeds throughout the landscape . without birds , the natural world would be a very different place . although birds face an on-going threat from human land development , there are actions that we can all take to help . many countries and local governements have already passed important laws that restrict the use of poisonous pesticides . by using more natural , plant-based products , we can maintain our farms and gardens without the dangerous side effects . in addition , as our global populations continue to grow and people need places to call home , green spaces can offer both bird habitat as well as a peaceful and natural place for us to enjoy . small changes at home can also make a huge difference . by hanging up feeders and building bird houses in outdoor areas , we can provide much-needed food and safety during long migrations . turning out lights in suburban and urban environments can also help birds that look for stars to navigate . with our help , these sky travellers can reach their destination safely , and hopefully keep returning year after year .
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while flying , birds can lose almost one percent of their body weight an hour , so packing on the pounds is crucial to their survival . however , more than the physical stress , migrating birds are now facing a new source of hardship : landscape change . just imagine you 're the one getting ready to take a trip .
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while migration is very physically demanding , birds face additional hardship due to human induced landscape change . what are some of the obstacles that birds may come across during their journey ? what can you do to help ?
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we all know about the dinosaurs that once roamed the planet , but long after they went extinct , great beasts we call the megafauna lived on every continent . in the americas , ground sloths the size of elephants pulled down trees with their claws . saber-toothed cats the size of brown bears hunted in packs , but they were no match for short-faced bears , which stood thirteen feet on their hind legs , and are likely to have driven these cats away from their prey . there were armadillos as big as small cars , an eight foot beaver , and a bird with a 26 foot wingspan . almost everywhere , the world 's megafauna were driven to extinction , often by human hunters . some species still survive in parts of africa and asia . in other places , you can still see the legacy of these great beasts . most trees are able to resprout where their trunk is broken to withstand the loss of much of their bark and to survive splitting , twisting and trampling , partly because they evolved to survive attacks by elephants . the american pronghorn can run so fast because it evolved to escape the american cheetah . the surviving animals live in ghost ecosystems adapted to threats from species that no longer exist . today , it may be possible to resurrect those ghosts , to bring back lost species using genetic material . for instance , there 's been research in to cloning woolly mammoths from frozen remains . but even if it 's not possible , we can still restore many of the ecosystems the world has lost . how ? by making use of abandoned farms . as the market for food is globalized , infertile land becomes uncompetitive . farmers in barren places ca n't compete with people growing crops on better land elsewhere . as a result , farming has started to retreat from many regions , and trees have started to return . one estimate claims that two-thirds of land in the us that was once forested but was cleared for farming has become forested again . another estimate suggests that by 2030 , an area in europe the size of poland will be vaccated by farmers . so even if we ca n't use dna to bring back ground sloths and giant armadillos , we can restore bears , wolves , pumas lynx , moose and bison to the places where they used to live . some of these animals can reshape their surroundings , creating conditions that allow other species to thrive . when wolves were reintroduced to the yellowstone national park in 1995 , they quickly transformed the ecosystem . where they reduced the numbers of overpopulated deer , vegetation began to recover . the height of some trees quintupled in just six years . as forests returned , so did songbirds . beavers , which eat trees , multiplied in the rivers , and their dams provided homes for otters , muskrats , ducks , frogs and fish . the wolves killed coyotes , allowing rabbits and mice to increase , providing more food for hawks , weasels , foxes and badgers . bald eagles and ravens fed on the carrion that the wolves abandoned . so did bears , which also ate the berries on the returning shrubs . bison numbers rose as they browsed the revitalized forests . the wolves changed almost everything . this is an example of a trophic cascade , a change at the top of the food chain that tumbles all the way to the bottom , affecting every level . the discovery of widespread trophic cascades may be one of the most exciting scientific findings of the past half century . they tell us that ecosystems that have lost just one or two species of large animals can behave in radically different ways from those that retain them . all over the world , new movements are trying to catalyze the restoration of nature in a process called rewilding . this means undoing some of the damage we 've caused , reestablishing species which have been driven out , and then stepping back . there is no attempt to create an ideal ecosystem , to produce a heath , a rainforest or a coral reef . rewilding is about bringing back the species that drive dynamic processes and then letting nature take its course . but it 's essential that rewilding must never be used as an excuse to push people off the land . it should happen only with the consent and enthusiasm of the people who work there . imagine standing on a cliff in england , watching sperm whales attacking shoals of herring as they did within sight of the shore until the 18th century . by creating marine reserves in which no commerical fishing takes place , that can happen again . imagine a european serengeti full of the animals that used to live there : hippos , rhinos , elephants , hyenas and lions . what rewilding reintroduces , alongside the missing animals and plants , is that rare species called hope . it tells us that ecological change need not always proceed in the same direction . the silent spring could be followed by a wild summer .
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there were armadillos as big as small cars , an eight foot beaver , and a bird with a 26 foot wingspan . almost everywhere , the world 's megafauna were driven to extinction , often by human hunters . some species still survive in parts of africa and asia .
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if extinction is forever , to what extent can an ecosystem missing much of its megafauna truly be restored ?
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the naming of clouds on a cold december evening in 1802 , a nervous young man named luke howard stood before the assembled members of a london science club about to give a lecture that would change his life and go on to change humanity 's understanding of the skies . luke howard was a pharmacist by profession , but he was a meteorologist by inclination , having been obsessed by clouds and weather since childhood . as a school boy , he spent hours staring out of the classroom window , gazing at the passing clouds . like everyone else at the time , he had no idea how clouds formed , or how they stayed aloft . but he enjoyed observing their endless transformations . by his own admission , luke paid little attention to his lessons , but fortunately for the future of meteorology , he managed to pick up a good knowledge of latin . compared to the other natural sciences , meteorology , the study of weather , was a late developer , mainly because weather is elusive . you ca n't snap off a piece of rainbow or a section of cloud for convenient study . you can , of course , collect rain water in calibrated containers , but all you really end up with are buckets of water . understanding clouds required a different approach , which is where luke howard 's idea came in . his simple insight based on years of observation was that clouds have many individual shapes but they have few basic forms . in fact , all clouds belong to one of three principle types to which howard gave the names : cirrus , latin for tendril or hair , cumulus , heap or pile , and stratus , layer or sheet . but that was n't the clever part . clouds are constantly changing , merging , rising , falling , and spreading throughout the atmosphere , rarely maintaining the same shapes for more than a few minutes . any successful naming system had to accommodate this essential instability , as howard realized . so , in addition to the three main cloud types , he introduced a series of intermediate and compound types as a way of including the regular transitions that occur among clouds . a high , whispy cirrus cloud that descended and spread into a sheet was named cirrostratus , while groups of fluffy cumulus clouds that joined up and spread were named stratocumulus . howard identified seven cloud types , but these have since been expanded to ten , cloud nine being the towering cumulonimbus thunder cloud , which is probably why being on cloud nine means to be on top of the world . howard 's classification had an immediate international impact . the german poet and scientist j.w . von goethe wrote a series of poems in praise of howard 's clouds , which ended with the memorable lines , `` as clouds ascend , are folded , scatter , fall , let the world think of thee who taught it all , '' while percy shelley also wrote a poem `` the cloud , '' in which each of howard 's seven cloud types was characterized in turn . but perhaps the most impressive response to the naming of clouds was by the painter john constable , who spent two summers on hampstead heath painting clouds in the open air . once they had been named and classified , clouds became easier to understand as the visible signs of otherwise invisible atmospheric processes . clouds write a kind of journal on the sky that allows us to understand the circulating patterns of weather and climate . perhaps the most important breakthrough in understanding clouds was realizing that they are subject to the same physical laws as everything else on earth . clouds , for example , do not float , but fall slowly under the influence of gravity . some of them stay aloft due to upward convection from the sun-heated ground , but most are in a state of slow , balletic descent . `` clouds are the patron goddesses of idle fellows , '' as the greek dramatist aristophanes wrote in 420 b.c . and nephology , the study of clouds , remains a daydreamer 's science , aptly founded by a thoughtful young man whose favorite activity was staring out of the window at the sky .
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you can , of course , collect rain water in calibrated containers , but all you really end up with are buckets of water . understanding clouds required a different approach , which is where luke howard 's idea came in . his simple insight based on years of observation was that clouds have many individual shapes but they have few basic forms . in fact , all clouds belong to one of three principle types to which howard gave the names : cirrus , latin for tendril or hair , cumulus , heap or pile , and stratus , layer or sheet . but that was n't the clever part .
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the names of the clouds were derived from which language ?
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what could octopuses possibly have in common with us ? after all , they do n't have lungs , spines , or even a plural noun we can all agree on . but what they do have is the ability to solve puzzles , learn through observation , and even use tools , just like some other animals we know . and what makes octopus intelligence so amazing is that it comes from a biological structure completely different from ours . the 200 or so species of octopuses are mollusks belonging to the order cephalopoda , greek for head-feet . those heads contain impressively large brains , with a brain to body ratio similar to that of other intelligent animals , and a complex nervous system with about as many neurons as that of a dog . but instead of being centralized in the brain , these 500 million neurons are spread out in a network of interconnected ganglia organized into three basic structures . the central brain only contains about 10 % of the neurons , while the two huge optic lobes contain about 30 % . the other 60 % are in the tentacles , which for humans would be like our arms having minds of their own . this is where things get even more interesting . vertebrates like us have a rigid skeleton to support our bodies , with joints that allow us to move . but not all types of movement are allowed . you ca n't bend your knee backwards , or bend your forearm in the middle , for example . cephalopods , on the other hand , have no bones at all , allowing them to bend their limbs at any point and in any direction . so shaping their tentacles into any one of the virtually limitless number of possible arrangements is unlike anything we are used to . consider a simple task , like grabbing and eating an apple . the human brain contains a neurological map of our body . when you see the apple , your brain 's motor center activates the appropriate muscles , allowing you to reach out with your arm , grab it with your hand , bend your elbow joint , and bring it to your mouth . for an octopus , the process is quite different . rather than a body map , the cephalopod brain has a behavior library . so when an octopus sees food , its brain does n't activate a specific body part , but rather a behavioral response to grab . as the signal travels through the network , the arm neurons pick up the message and jump into action to command the movement . as soon as the arm touches the food , a muscle activation wave travels all the way through the arm to its base , while the arm sends back another wave from the base to the tip . the signals meet halfway between the food and the base of the arm , letting it know to bend at that spot . what all this means is that each of an octopus 's eight arms can essentially think for itself . this gives it amazing flexibility and creativity when facing a new situation or problem , whether its opening a bottle to reach food , escaping through a maze , moving around in a new environment , changing the texture and the color of its skin to blend into the scenery , or even mimicking other creatures to scare away enemies . cephalopods may have evolved complex brains long before our vertebrate relatives . and octopus intelligence is n't just useful for octopuses . their radically different nervous system and autonomously thinking appendages have inspired new research in developing flexible robots made of soft materials . and studying how intelligence can arise along such a divergent evolutionary path can help us understand more about intelligence and consciousness in general . who knows what other forms of intelligent life are possible , or how they process the world around them .
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when you see the apple , your brain 's motor center activates the appropriate muscles , allowing you to reach out with your arm , grab it with your hand , bend your elbow joint , and bring it to your mouth . for an octopus , the process is quite different . rather than a body map , the cephalopod brain has a behavior library .
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what does the sentence `` each arm in an octopus has a mind of its own '' mean ?
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why does your mouth feel like it 's on fire when you eat a spicy pepper ? and how do you soothe the burn ? why does wasabi make your eyes water ? and how spicy is the spiciest spice ? let 's back up a bit . first , what is spiciness ? even though we often say that something tastes spicy , it 's not actually a taste , like sweet or salty or sour . instead , what 's really happening is that certain compounds in spicy foods activate the type of sensory neurons called polymodal nociceptors . you have these all over your body , including your mouth and nose , and they 're the same receptors that are activated by extreme heat . so , when you eat a chili pepper , your mouth feels like it 's burning because your brain actually thinks it 's burning . the opposite happens when you eat something with menthol in it . the cool , minty compound is activating your cold receptors . when these heat-sensitive receptors are activated , your body thinks it 's in contact with a dangerous heat source and reacts accordingly . this is why you start to sweat , and your heart starts beating faster . the peppers have elicited the same fight-or-flight response with which your body reacts to most threats . but you may have noticed that not all spicy foods are spicy in the same way . and the difference lies in the types of compounds involved . the capsaicin and piperine , found in black pepper and chili peppers , are made up of larger , heavier molecules called alkylamides , and those mostly stay in your mouth . mustard , horseradish , and wasabi are made up of smaller molecules , called isothiocyanates , that easily float up into your sinuses . this is why chili peppers burn your mouth , and wasabi burns your nose . the standard measure of a food 's spiciness is its rating on the scoville scale , which measures how much its capsaicin content can be diluted before the heat is no longer detectable to humans . a sweet bell pepper gets 0 scoville heat units , while tabasco sauce clocks in between 1,200-2,400 units . the race to create the hottest pepper is a constant battle , but two peppers generally come out on top : the trinidad moruga scorpion and the carolina reaper . these peppers measure between 1.5 and 2 million scoville heat units , which is about half the units found in pepper spray . so , why would anyone want to eat something that causes such high levels of pain ? nobody really knows when or why humans started eating hot peppers . archaeologists have found spices like mustard along with human artifacts dating as far back as 23,000 years ago . but they do n't know whether the spices were used for food or medication or just decoration . more recently , a 6,000 year old crockpot , lined with charred fish and meat , also contained mustard . one theory says that humans starting adding spices to food to kill off bacteria . and some studies show that spice developed mostly in warmer climates where microbes also happen to be more prevalent . but why we continue to subject ourselves to spicy food today is still a bit of a mystery . for some people , eating spicy food is like riding rollercoasters ; they enjoy the ensuing thrill , even if the immediate sensation is unpleasant . some studies have even shown that those who like to eat hot stuff are more likely to enjoy other adrenaline-rich activities , like gambling . the taste for spicy food may even be genetic . and if you 're thinking about training a bit , to up your tolerance for spice , know this : according to some studies , the pain does n't get any better . you just get tougher . in fact , researchers have found that people who like to eat spicy foods do n't rate the burn any less painful than those who do n't . they just seem to like the pain more . so , torment your heat receptors all you want , but remember , when it comes to spicy food , you 're going to get burned .
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why does wasabi make your eyes water ? and how spicy is the spiciest spice ? let 's back up a bit .
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which one of these is not a use for spice plants ?
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