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it 's not hard to imagine a world where at any given moment , you and everyone you know could be wiped out without warning at the push of a button . this was the reality for millions of people during the 45-year period after world war ii , now known as the cold war . as the united states and soviet union faced off across the globe , each knew that the other had nuclear weapons capable of destroying it . and destruction never loomed closer than during the 13 days of the cuban missile crisis . in 1961 , the u.s. unsuccessfully tried to overthrow cuba 's new communist government . that failed attempt was known as the bay of pigs , and it convinced cuba to seek help from the u.s.s.r. soviet premier nikita khrushchev was happy to comply by secretly deploying nuclear missiles to cuba , not only to protect the island , but to counteract the threat from u.s. missiles in italy and turkey . by the time u.s. intelligence discovered the plan , the materials to create the missiles were already in place . at an emergency meeting on october 16 , 1962 , military advisors urged an airstrike on missile sites and invasion of the island . but president john f. kennedy chose a more careful approach . on october 22 , he announced that the the u.s. navy would intercept all shipments to cuba . there was just one problem : a naval blockade was considered an act of war . although the president called it a quarantine that did not block basic necessities , the soviets did n't appreciate the distinction . in an outraged letter to kennedy , khrushchev wrote , `` the violation of freedom to use international waters and international airspace is an act of aggression which pushes mankind toward the abyss of world nuclear missile war . '' thus ensued the most intense six days of the cold war . while the u.s. demanded the removal of the missiles , cuba and the u.s.s.r insisted they were only defensive . and as the weapons continued to be armed , the u.s. prepared for a possible invasion . on october 27 , a spy plane piloted by major rudolph anderson was shot down by a soviet missile . the same day , a nuclear-armed soviet submarine was hit by a small-depth charge from a u.s. navy vessel trying to signal it to come up . the commanders on the sub , too deep to communicate with the surface , thought war had begun and prepared to launch a nuclear torpedo . that decision had to be made unanimously by three officers . the captain and political officer both authorized the launch , but vasili arkhipov , second in command , refused . his decision saved the day and perhaps the world . but the crisis was n't over . for the first time in history , the u.s. military set itself to defcon 2 , the defense readiness one step away from nuclear war . with hundreds of nuclear missiles ready to launch , the metaphorical doomsday clock stood at one minute to midnight . but diplomacy carried on . in washington , d.c. , attorney general robert kennedy secretly met with soviet ambassador anatoly dobrynin . after intense negotiation , they reached the following proposal . the u.s. would remove their missiles from turkey and italy and promise to never invade cuba in exchange for the soviet withdrawal from cuba under u.n. inspection . once the meeting had concluded , dobrynin cabled moscow saying time is of the essence and we should n't miss the chance . and at 9 a.m. the next day , a message arrived from khrushchev announcing the soviet missiles would be removed from cuba . the crisis was now over . while criticized at the time by their respective governments for bargaining with the enemy , contemporary historical analysis shows great admiration for kennedy 's and khrushchev 's ability to diplomatically solve the crisis . but the disturbing lesson was that a slight communication error , or split-second decision by a commander , could have thwarted all their efforts , as it nearly did if not for vasili arkhipov 's courageous choice . the cuban missile crisis revealed just how fragile human politics are compared to the terrifying power they can unleash .
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after intense negotiation , they reached the following proposal . the u.s. would remove their missiles from turkey and italy and promise to never invade cuba in exchange for the soviet withdrawal from cuba under u.n. inspection . once the meeting had concluded , dobrynin cabled moscow saying time is of the essence and we should n't miss the chance .
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the soviet union placed missiles in cuba in order to ___ the island of cuba .
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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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how should us companies handle a cyber attack by a sovereign nation ?
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how high can you count on your fingers ? it seems like a question with an obvious answer . after all , most of us have ten fingers , or to be more precise , eight fingers and two thumbs . this gives us a total of ten digits on our two hands , which we use to count to ten . it 's no coincidence that the ten symbols we use in our modern numbering system are called digits as well . but that 's not the only way to count . in some places , it 's customary to go up to twelve on just one hand . how ? well , each finger is divided into three sections , and we have a natural pointer to indicate each one , the thumb . that gives us an easy to way to count to twelve on one hand . and if we want to count higher , we can use the digits on our other hand to keep track of each time we get to twelve , up to five groups of twelve , or 60 . better yet , let 's use the sections on the second hand to count twelve groups of twelve , up to 144 . that 's a pretty big improvement , but we can go higher by finding more countable parts on each hand . for example , each finger has three sections and three creases for a total of six things to count . now we 're up to 24 on each hand , and using our other hand to mark groups of 24 gets us all the way to 576 . can we go any higher ? it looks like we 've reached the limit of how many different finger parts we can count with any precision . so let 's think of something different . one of our greatest mathematical inventions is the system of positional notation , where the placement of symbols allows for different magnitudes of value , as in the number 999 . even though the same symbol is used three times , each position indicates a different order of magnitude . so we can use positional value on our fingers to beat our previous record . let 's forget about finger sections for a moment and look at the simplest case of having just two options per finger , up and down . this wo n't allow us to represent powers of ten , but it 's perfect for the counting system that uses powers of two , otherwise known as binary . in binary , each position has double the value of the previous one , so we can assign our fingers values of one , two , four , eight , all the way up to 512 . and any positive integer , up to a certain limit , can be expressed as a sum of these numbers . for example , the number seven is 4+2+1 . so we can represent it by having just these three fingers raised . meanwhile , 250 is 128+64+32+16+8+2 . how high an we go now ? that would be the number with all ten fingers raised , or 1,023 . is it possible to go even higher ? it depends on how dexterous you feel . if you can bend each finger just halfway , that gives us three different states - down , half bent , and raised . now , we can count using a base-three positional system , up to 59,048 . and if you can bend your fingers into four different states or more , you can get even higher . that limit is up to you , and your own flexibility and ingenuity . even with our fingers in just two possible states , we 're already working pretty efficiently . in fact , our computers are based on the same principle . each microchip consists of tiny electrical switches that can be either on or off , meaning that base-two is the default way they represent numbers . and just as we can use this system to count past 1,000 using only our fingers , computers can perform billions of operations just by counting off 1 's and 0 's .
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if you can bend each finger just halfway , that gives us three different states - down , half bent , and raised . now , we can count using a base-three positional system , up to 59,048 . and if you can bend your fingers into four different states or more , you can get even higher .
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the number 59,048 equals :
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will winning the lottery make you happier ? imagine winning a multi-million dollar lottery tomorrow . if you 're like many of us , you 'd be ecstatic , unable to believe your good luck . but would that joy still be there a few years later ? maybe not . a famous study of 22 lottery winners showed that months after winning , their average reported levels of happiness had increased no more than that of a control group who had n't won the lottery . some were actually unhappier than they had been before winning . and later studies have confirmed that our emotional well-being , how often and how intensely we feel things like joy , sorrow , anxiety , or anger , do n't seem to improve with wealth or status beyond a certain point . this has to do with a phenomenon known as hedonic adaptation , or the hedonic treadmill . it describes our tendency to adapt to new situations to maintain a stable emotional equilibrium . when it comes to feeling happy , most of us seem to have a base level that stays more or less constant throughout our existence . of course , the novelty of better food , superior vacations , and more beautiful homes can at first make you feel like you 're walking on air , but as you get used to those things , you revert to your default emotional state . that might sound pretty gloomy , but hedonic adaptation makes us less emotionally sensitive to any kind of change , including negative ones . the study with the lottery winners also looked at people who had suffered an accident that left them paralyzed . when asked several months after their accidents how happy they were , they reported levels of happiness approaching their original baseline . so while the hedonic treadmill may inhibit our enjoyment of positive changes , it seems to also enable our resilience in recovering from adversity . there are other reasons that winning the lottery may not make us happier in the long run . it can be difficult to manage large sums of money , and some lottery winners wind up spending or losing it all quickly . it can also be socially isolating . some winners experience a deluge of unwelcome requests for money , so they wind up cutting themselves off from others . and wealth may actually make us meaner . in one study , participants played a rigged game of monopoly where the experimenters made some players rich quickly . the wealthy players started patronizing the poorer players and hogging the snacks they were meant to share . but just because a huge influx of cash is n't guaranteed to bring joy into your life does n't mean that money can never make us happier . findings show that we adapt to extrinsic and material things , like a new car or a bigger house , much faster than we do to novel experiences , like visiting a new place or learning a new skill . so by that reasoning , the more you spend money on experiences rather than things , the happier you 'd be . and there 's another way to turn your money into happiness : spend it on other people . in one study , participants were given some money and were either asked to spend it on themselves or on someone else . later that evening , researchers called up these participants and asked them how happy they were . the happiness levels of those who had spent the money on others were significantly greater than that of those who had spent it on themselves . and that seems to be true around the world . another study examined the generosity of over 200,000 people from 136 countries . in over 90 % of these countries , people who donated tended to be happier than those who did n't . but this may all be easier said than done . let 's say a million dollars falls into your lap tomorrow . what do you do with it ?
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and that seems to be true around the world . another study examined the generosity of over 200,000 people from 136 countries . in over 90 % of these countries , people who donated tended to be happier than those who did n't .
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generosity has a way of making both the donor and receiver happy . explain .
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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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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 .
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some discoveries take centuries and some happen in an instant . research a notable discovery in a field that most interests you and explain how it unfolded .
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acids and bases are everywhere . they 're used to make foods , soaps and detergents , fertilizers , explosives , dyes , plastics , pesticides , even paper . our stomachs are very acidic . our blood is slightly basic . our proteins are made up of amino acids , and the letters in our genetic code , those as , ts , cs , and gs , are all bases . you were probably taught how acids and bases behave on the molecular level . you were probably never taught that a long time ago , like ancient greek ago , before anyone knew about atoms or molecules , acids and bases were defined by how they behaved . acids tasted sour and corroded metal . bases felt slippery and could somehow counteract acids . when molecules dissolved in water interact , they are exchanging two main currencies with their surroundings : protons , also known as hydrogen ions , and electrons . depending on how a molecule is composed or shaped , it may be willing to donate or accept either protons or electrons with some other community member . and some molecules are far more aggressive than others when it comes to donating or accepting either currency . remember that protons are positively charged and electrons are negatively charged . so , if a molecule is willing to give up a proton , that 's not too different from it being willing to accept an electron -- either way it 's becoming more negatively charged . other molecules are willing to accept a proton or give up an electron . these are becoming more positively charged . some substances are so aggressive about donating their protons that when they get a chance , all of the molecules in a sample will dump a proton , sometimes more than one , to the surrounding water molecules . we call these strong acids . meanwhile , some compounds are so ready to accept a proton that they wo n't wait around , they 'll just rip one off water , which usually has two protons but is generous enough to hang out with just one . we call these strong bases . other acids and bases are not so strong . they may donate just a few of their protons to water or accept just a few protons from water , but most of their molecules stay exactly the same . if left alone in water , they 'll reach some equilibrium point where maybe only one out of a hundred or one out of ten thousand of their molecules has exchanged currency with water . as you might guess , we label these acids and bases weak , but in the common sense of the word , they 're not weak . the vinegar in your salad dressing that you can smell from across the room , that is a weak acid . the ammonia you spray on glass for a streak-free shine , that is a weak base . so , it does n't take much to be an active player in the chemical economy . most acid-base chemistry takes place in water , which can act as either an acid or a base , accepting deposits and enabling withdrawals like a 24-hour molecular atm . and when a proton-deposit customer , that 's an acid , and a proton-withdrawal customer , the base , shop at the same time , their net effect on water 's account may cancel out , and we call this neutralization . now , certain molecules can behave as acids or bases without water , but that 's another story . let 's end by saluting water as the resilient and fair banker for acids and bases . it 's always open for business , does n't charge interest , and will never foreclose on your molecules , which is more than i can say for [ bleep ] . waah-waah .
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so , it does n't take much to be an active player in the chemical economy . most acid-base chemistry takes place in water , which can act as either an acid or a base , accepting deposits and enabling withdrawals like a 24-hour molecular atm . and when a proton-deposit customer , that 's an acid , and a proton-withdrawal customer , the base , shop at the same time , their net effect on water 's account may cancel out , and we call this neutralization .
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if you were to mix a strong acid with a weak base , would they completely neutralize each other ?
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in mythological ancient greece , soaring above crete on wings made from wax and feathers , icarus , the son of daedalus , defied the laws of both man and nature . ignoring the warnings of his father , he rose higher and higher . to witnesses on the ground , he looked like a god , and as he peered down from above , he felt like one , too . but , in mythological ancient greece , the line that separated god from man was absolute and the punishment for mortals who attempted to cross it was severe . such was the case for icarus and daedalus . years before icarus was born , his father daedalus was highly regarded as a genius inventor , craftsman , and sculptor in his homeland of athens . he invented carpentry and all the tools used for it . he designed the first bathhouse and the first dance floor . he made sculptures so lifelike that hercules mistook them for actual men . though skilled and celebrated , daedalus was egotistical and jealous . worried that his nephew was a more skillful craftsman , daedalus murdered him . as punishment , daedalus was banished from athens and made his way to crete . preceded by his storied reputation , daedalus was welcomed with open arms by crete 's king minos . there , acting as the palace technical advisor , daedalus continued to push the boundaries . for the king 's children , he made mechanically animated toys that seemed alive . he invented the ship 's sail and mast , which gave humans control over the wind . with every creation , daedalus challenged human limitations that had so far kept mortals separate from gods , until finally , he broke right through . king minos 's wife , pasiphaë , had been cursed by the god poseidon to fall in love with the king 's prized bull . under this spell , she asked daedalus to help her seduce it . with characteristic audacity , he agreed . daedalus constructed a hollow wooden cow so realistic that it fooled the bull . with pasiphaë hiding inside daedalus 's creation , she conceived and gave birth to the half-human half-bull minotaur . this , of course , enraged the king who blamed daedalus for enabling such a horrible perversion of natural law . as punishment , daedalus was forced to construct an inescapable labyrinth beneath the palace for the minotaur . when it was finished , minos then imprisoned daedalus and his only son icarus within the top of the tallest tower on the island where they were to remain for the rest of their lives . but daedalus was still a genius inventor . while observing the birds that circled his prison , the means for escape became clear . he and icarus would fly away from their prison as only birds or gods could do . using feathers from the flocks that perched on the tower , and the wax from candles , daedalus constructed two pairs of giant wings . as he strapped the wings to his son icarus , he gave a warning : flying too near the ocean would dampen the wings and make them too heavy to use . flying too near the sun , the heat would melt the wax and the wings would disintegrate . in either case , they surely would die . therefore , the key to their escape would be in keeping to the middle . with the instructions clear , both men leapt from the tower . they were the first mortals ever to fly . while daedalus stayed carefully to the midway course , icarus was overwhelmed with the ecstasy of flight and overcome with the feeling of divine power that came with it . daedalus could only watch in horror as icarus ascended higher and higher , powerless to change his son 's dire fate . when the heat from the sun melted the wax on his wings , icarus fell from the sky . just as daedalus had many times ignored the consequences of defying the natural laws of mortal men in the service of his ego , icarus was also carried away by his own hubris . in the end , both men paid for their departure from the path of moderation dearly , icarus with his life and daedalus with his regret .
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with every creation , daedalus challenged human limitations that had so far kept mortals separate from gods , until finally , he broke right through . king minos 's wife , pasiphaë , had been cursed by the god poseidon to fall in love with the king 's prized bull . under this spell , she asked daedalus to help her seduce it .
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enraged by icarus , king minos had him create a labyrinth to imprison
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in the early 1960s , dick fosbury tried his hand at almost every sport , but never excelled at anything , until , at the age of 16 , he turned to the high jump . but when he could n't compete against the strong athletes at his college using the standard high jump techniques of the time , fosbury tried to jump a different way : backwards . instead of jumping with his face towards the bar , bringing each leg over in the traditional straddle method , he jumped with his back towards the bar . fosbury improved his record by over half a foot , and left his coaches amazed by this strange new style of high jumping . during the next few years , fosbury perfected his high jump style , won the u.s. national trials , and assured his place in the 1968 olympics in mexico . in the olympic games , fosbury amazed the world with his new technique , winning a gold metal with an olympic record leap of 2.24 meters . by the next olympic games , almost all of the competing of high jumpers had adopted what came to be known as the fosbury flop . what 's the secret behind the technique ? it lies in a physics concept called the center of mass . for every object , we can locate the average position of all of its mass by taking into account how the mass is spread around the object . for instance , the center of mass of a flat , rectangular object of uniform density will be in the intersection of both diagonals , in equal distance from each corner . we can find the center of mass for other objects by similar calculations , or by finding the object 's balancing point , which lies right underneath its center of mass . try balancing a broom by holding it and slowly bringing your hands together until they meet . this balancing point lies right underneath the broom 's center of mass . we humans also have a center of mass . when most people stand up , their center of mass is around the belly , but what happens to your center of mass when you lift your hands in the air ? your center of mass moves upwards . it moves all the time as you move through the day , based on how your body is positioned . it can even move outside of your body . when you bend forward , your center of mass is located below your bent belly in a place where there is no mass at all . weird to think about , but that 's the average position of all your mass . many objects ' center of mass are outside their bodies . think of doughnuts or boomerangs . now look at the fosbury flop , and follow the position of the center of mass of the jumper . the jumper runs very fast , so he can divert his horizontal velocity to vertical velocity , and jumps . wait for it ... there . look at the jumper 's center of mass as his body bends backward . it 's below the bar . that is the secret behind the jump . with the old , pre-fosbury techniques , the jumper had to apply enough force to lift his center of mass above the bar by a few inches in order to clear it . the fosbury flopper does n't have to do that . the genius of the fosbury flop is that the jumper can apply the same amount of force , but raise his body much higher than before . that means he can raise the bar so high that even when his center of mass ca n't go any higher , his arching body can . fosbury 's technique brought the high jump to new heights by splitting the jumper 's body away from his center of mass , giving it that much more room to clear higher and higher bars . so the fosbury flop may be sports history 's only great leap forward , that is also a great leap backward .
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when most people stand up , their center of mass is around the belly , but what happens to your center of mass when you lift your hands in the air ? your center of mass moves upwards . it moves all the time as you move through the day , based on how your body is positioned .
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how is it possible to jump over the bar without bringing your center of mass above it ?
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you 're telling a friend an amazing story , and you just get to the best part when suddenly he interrupts , `` the alien and i , '' not `` me and the alien . '' most of us would probably be annoyed , but aside from the rude interruption , does your friend have a point ? was your sentence actually grammatically incorrect ? and if he still understood it , why does it even matter ? from the point of view of linguistics , grammar is a set of patterns for how words are put together to form phrases or clauses , whether spoken or in writing . different languages have different patterns . in english , the subject normally comes first , followed by the verb , and then the object , while in japanese and many other languages , the order is subject , object , verb . some scholars have tried to identify patterns common to all languages , but apart from some basic features , like having nouns or verbs , few of these so-called linguistic universals have been found . and while any language needs consistent patterns to function , the study of these patterns opens up an ongoing debate between two positions known as prescriptivism and descriptivism . grossly simplified , prescriptivists think a given language should follow consistent rules , while descriptivists see variation and adaptation as a natural and necessary part of language . for much of history , the vast majority of language was spoken . but as people became more interconnected and writing gained importance , written language was standardized to allow broader communication and ensure that people in different parts of a realm could understand each other . in many languages , this standard form came to be considered the only proper one , despite being derived from just one of many spoken varieties , usually that of the people in power . language purists worked to establish and propagate this standard by detailing a set of rules that reflected the established grammar of their times . and rules for written grammar were applied to spoken language , as well . speech patterns that deviated from the written rules were considered corruptions , or signs of low social status , and many people who had grown up speaking in these ways were forced to adopt the standardized form . more recently , however , linguists have understood that speech is a separate phenomenon from writing with its own regularities and patterns . most of us learn to speak at such an early age that we do n't even remember it . we form our spoken repertoire through unconscious habits , not memorized rules . and because speech also uses mood and intonation for meaning , its structure is often more flexible , adapting to the needs of speakers and listeners . this could mean avoiding complex clauses that are hard to parse in real time , making changes to avoid awkward pronounciation , or removing sounds to make speech faster . the linguistic approach that tries to understand and map such differences without dictating correct ones is known as descriptivism . rather than deciding how language should be used , it describes how people actually use it , and tracks the innovations they come up with in the process . but while the debate between prescriptivism and descriptivism continues , the two are not mutually exclusive . at its best , prescriptivism is useful for informing people about the most common established patterns at a given point in time . this is important , not only for formal contexts , but it also makes communication easier between non-native speakers from different backgrounds . descriptivism , on the other hand , gives us insight into how our minds work and the instinctive ways in which we structure our view of the world . ultimately , grammar is best thought of as a set of linguistic habits that are constantly being negotiated and reinvented by the entire group of language users . like language itself , it 's a wonderful and complex fabric woven through the contributions of speakers and listeners , writers and readers , prescriptivists and descriptivists , from both near and far .
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language purists worked to establish and propagate this standard by detailing a set of rules that reflected the established grammar of their times . and rules for written grammar were applied to spoken language , as well . speech patterns that deviated from the written rules were considered corruptions , or signs of low social status , and many people who had grown up speaking in these ways were forced to adopt the standardized form .
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the spoken version of a language has :
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`` war and peace , '' a tome , a slog , the sort of book you should n't read in bed because if you fall asleep , it could give you a concussion , right ? only partly . `` war and peace '' is a long book , sure , but it 's also a thrilling examination of history , populated with some of the deepest , most realistic characters you 'll find anywhere . and if its length intimidates you , just image how poor tolstoy felt . in 1863 , he set out to write a short novel about a political dissident returning from exile in siberia . five years later , he had produced a 1,200 page epic featuring love stories , battlefields , bankruptcies , firing squads , religious visions , the burning of moscow , and a semi-domesticated bear , but no exile and no political dissidents . here 's how it happened . tolstoy , a volcanic soul , was born to a famously eccentric aristocratic family in 1828 . by the time he was 30 , he had already dropped out of kazan university , gambled away the family fortune , joined the army , written memoirs , and rejected the literary establishment to travel europe . he then settled into yasnaya polyana , his ancestral mansion , to write about the return of the decembrists , a band of well-born revolutionaries pardoned in 1856 after 30 years in exile . but , tolstoy thought , how could he tell the story of the decembrists return from exile without telling the story of 1825 , when they revolted against the conservative tsar nicholas i ? and how could he do that without telling the story of 1812 , when napoleon 's disastrous invasion of russia helped trigger the authoritarianism the decembrists were rebelling against ? and how could he tell the story of 1812 without talking about 1805 , when the russians first learned of the threat napoleon posed after their defeat at the battle of austerlitz ? so tolstoy began writing , both about the big events of history and the small lives that inhabit those events . he focused on aristocrats , the class he knew best . the book only occasionally touches on the lives of the vast majority of the russian population , who were peasants , or even serfs , farmers bound to serve the owners of the land on which they lived . `` war and peace '' opens on the eve of war between france and russia . aristocrats at a cocktail party fret about the looming violence , but then change the topic to those things aristocrats always seem to care about : money , sex , and death . this first scene is indicative of the way the book bounces between the political and personal over an ever-widening canvas . there are no main characters in `` war and peace . '' instead , readers enter a vast interlocking web of relationships and questions . will the hapless and illegitimate son of a count marry a beautiful but conniving princess ? will his only friend survive the battlefields of austria ? and what about that nice young girl falling in love with both men at once ? real historical figures mix and mingle with all these fictional folk , napoleon appears several times , and even one of tolstoy 's ancestors plays a background part . but while the characters and their psychologies are gripping , tolstoy is not afraid to interrupt the narrative to pose insightful questions about history . why do wars start ? what are good battlefield tactics ? do nations rise and fall on the actions of so-called great men like napoleon , or are there larger cultural and economic forces at play ? these extended digressions are part of what make `` war and peace '' so panoramic in scope . but for some 19th century critics , this meant `` war and peace '' barely felt like a novel at all . it was a `` large , loose , baggy monster , '' in the words of henry james . tolstoy , in fact , agreed . to him , novels were a western european form . russian writers had to write differently because russian people lived differently . `` what is 'war and peace ' ? '' he asked . `` it is not a novel . still less an epic poem . still less a historical chronicle . 'war and peace ' is what the author wanted and was able to express in the form in which it was expressed . '' it is , in other words , the sum total of tolstoy 's imaginative powers , and nothing less . by the time `` war and peace '' ends , tolstoy has brought his characters to the year 1820 , 36 years before the events he originally hoped to write about . in trying to understand his own times , he had become immersed in the years piled up behind him . the result is a grand interrogation into history , culture , philosophy , psychology , and the human response to war .
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russian writers had to write differently because russian people lived differently . `` what is 'war and peace ' ? '' he asked .
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`` war and peace '' primarily concerns the lives of :
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honeybees are fascinating creatures for a number of reasons : their incredible work ethic , the sugary sweet syrup they produce and their intricate social structure . but another reason is that honeybees are , in fact , excellent mathematicians . scientists claim the tiny insects can calculate angles , and can even comprehend the roundness of the earth . but there 's particular mathematical bee genius behind the most important aspect of honeybee life : the hive . just like humans , bees need food and shelter to stay alive . the hive is not only the bees ' home , but doubles as a place to store their honey . since it 's so central to survival , honeybees have to perfect the hive 's architectural design . if you examine any piece of honeycomb , you 'll see that it 's constructed from tightly packed hexagonal , or six-sided , cells . of all the possible designs , why do honeybees choose this one ? to understand , you need to think like a bee . bees need a secure place for their entire colony to live . similarly , there needs to be a place where their nectar can be stored and ripened suitably until it turns into honey . that means there 's a need for some serious space efficiency . a good solution is to build little storage units , or cells , just big enough for a bee to fit into , which can also double as the containers in which nectar is stored : the bees ' very own honey jars . the next thing , is to decide what the little cells should be made out of . bees do n't have beaks or arms to pick up things , but they are capable of producing wax . the thing is , producing it is a lot of hard work . bees have to consume 8 ounces of honey to produce just 1 ounce of wax . so they do n't want to waste it . so , they need a design that allows them to store the largest possible amount of honey using the least amount of wax . what shape does that ? imagining for a minute that all bees had to attend architecture academy and go to math class . let 's say they asked their geometry teacher , `` what shape would give us the most space to store our honey , but require the least amount of wax ? '' and then geometry teacher replied , `` the shape that you 're seeking is the circle . '' leaving the bees to return to their trial construction site and begin building their honeycomb using circular cells . after a while , some of them might have noticed a problem with their design : small gaps between the cells . `` we ca n't even fit in there ! that 's wasted space ! '' they might have thought . so , ignoring the geometry lesson , and taking matters into their own hands , the bees went back to the drawing board to rethink their beehive design . one suggested triangles , `` we can use triangles . look ! they fit together perfectly . '' another bee suggested squares . finally , a third bee piped up and said , `` pentagons do n't seem to work , but hexagons do ! we want the one that will use the least amount of wax and be able to store the most amount of honey . yes , i think that 's the hexagon . '' `` why ? '' `` it looks more like the circle than the others . '' `` but how do we know for sure ? '' to find out , the industrious insect architects calculated the areas of the triangle , the square and the hexagon and found that the hexagon was , in fact , the shape that gave them the most storage space . they agreed on an ideal size and returned to work . the space efficient comb that is a bee 's trademark today , is probably the result of this trial and error , but over long periods of evolutionary history . however , it paid off . peek into any hive -- with your protective goggles and netting on , of course -- and you 'll see the end result : a beautiful compact honeycomb that any architect would have be proud to design .
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imagining for a minute that all bees had to attend architecture academy and go to math class . let 's say they asked their geometry teacher , `` what shape would give us the most space to store our honey , but require the least amount of wax ? '' and then geometry teacher replied , `` the shape that you 're seeking is the circle . ''
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the question the bees asked their geometry teacher , “ what shape would give us the most space to store our honey and require the least amount of wax ? ” can be reworded to be more mathematical as : “ what shape maximizes ___________ for a given ____________ ? ”
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if you ever find yourself gazing at falling snow , why not catch a few snowflakes on your glove and examine their shapes ? you might notice that they look symmetrical , and if you look closely , you 'll see they have six sides . you could say a snowflake is simply frozen water , but compare one with an ice cube from the freezer , and you 'll realize they 're very different things . unlike ice cubes , formed when liquid freezes into a solid , snowflakes form when water vapor turns straight into ice . but that still does n't explain why snowflakes have six sides . to understand that , we need to delve deeper into the physics of water . water is made out of two hydrogen atoms and one oxygen atom . a single water molecule thus has ten protons and ten electrons , eight from oxygen and one from each hydrogen atom . the two electrons from oxygen 's outer shell are shared with two electrons from both hydrogens as they bond together , and the remaining four outer shell electrons from oxygen form two pairs . we call the bonds between these atoms covalent bonds . the pairs of electrons are all negatively charged . similar charges repel , so they tend to stay as far away from each other as possible . the pairs form four electron clouds , two of which are where the hydrogen and oxygen share electrons . the repulsion between the unbonded pairs is even stronger than repulsion between the shared pairs , so the two hydrogens get pushed a little further to an angle of 104.5 degrees . the water molecule as a whole is electrically neutral , but oxygen gets a larger share of electrons , making it slightly negative and the hydrogens slightly positive . due to its negative charge , the oxygen in one molecule is attracted to the positive charge of the hydrogen in another molecule . and so a weak bond between the two molecules , called a hydrogen bond , is formed . when water freezes , this bonding occurs on repeat , ultimately forming a hexagonal structure due to the angle between hydrogens and oxygen within each molecule . this is the seed of a snowflake , and it retains a hexagonal shape as it grows . as the snowflake moves through the air , water vapor molecules stick to the six sharp edges and expand the snowflake outwards , bit by bit . a snowflake 's developing shape depends on atmospheric conditions , like humidity and temperature . as a snowflake falls , changes in weather conditions can affect how it grows , and even small differences in the paths two snowflakes take will differentiate their shapes . however , since conditions at the six sharp edges of one snowflake are similar , a symmetric snowflake can grow . weather conditions affect snow on the ground , as well . warmer ground temperatures produce a wetter snow that is easier to pack because liquid water molecules help snowflakes stick to each other . melted snow also plays a critical role in another wintry activity , skiing . completely dry snow is very difficult to ski on because there 's too much friction between the jagged snowflakes and the ski surface . so what 's happening is that as skis move , they rub the surface of the snow and warm it up , creating a thin layer of water , which helps them slide along . so technically , it 's not really snow skiing , but water skiing . but it is true that no matter how hard you look , you 're almost definitely not going to find two identical snowflakes , and that 's a mystery that scientists are still trying to solve , though we know that it has to do with the many possible branching points in snowflake formation , and the differences in temperature and humidity , and while we wait for the answer , we can enjoy watching these tiny fractals falling from the sky .
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unlike ice cubes , formed when liquid freezes into a solid , snowflakes form when water vapor turns straight into ice . but that still does n't explain why snowflakes have six sides . to understand that , we need to delve deeper into the physics of water .
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why are snowflakes six-sided ?
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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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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 .
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which of the following foods has slow glucose release ?
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food does n't last . in days , sometimes hours , bread goes moldy , apple slices turn brown , and bacteria multiply in mayonnaise . but you can find all of these foods out on the shelf at the grocery store , hopefully unspoiled , thanks to preservatives . but what exactly are preservatives ? how do they help keep food edible and are they safe ? there are two major factors that cause food to go bad : microbes and oxidation . microbes like bacteria and fungi invade food and feed off its nutrients . some of these can cause diseases , like listeria and botulism . others just turn edibles into a smelly , slimy , moldy mess . meanwhile , oxidation is a chemical change in the food 's molecules caused by enzymes or free radicals which turn fats rancid and brown produce , like apples and potatoes . preservatives can prevent both types of deterioration . before the invention of artificial refrigeration , fungi and bacteria could run rampant in food . so we found ways to create an inhospitable environment for microbes . for example , making the food more acidic unravels enzymes that microbes need to survive . and some types of bacteria can actually help . for thousands of years , people preserved food using bacteria that produce lactic acid . the acid turns perishable vegetables and milk into longer lasting foods , like sauerkraut in europe , kimchi in korea , and yogurt in the middle east . these cultured foods also populate your digestive track with beneficial microbes . many synthetic preservatives are also acids . benzoic acid in salad dressing , sorbic acid in cheese , and propionic acid in baked goods . are they safe ? some studies suggest that benzoates , related to benzoic acid , contribute to hyperactive behavior . but the results are n't conclusive . otherwise , these acids seem to be perfectly safe . another antimicrobial strategy is to add a lot of sugar , like in jam , or salt , like in salted meats . sugar and salt hold on to water that microbes need to grow and actually suck moisture out of any cells that may be hanging around , thus destroying them . of course , too much sugar and salt can increase your risk of heart disease , diabetes , and high blood pressure , so these preservatives are best in moderation . antimicrobial nitrates and nitrites , often found in cured meats , ward off the bacteria that cause botulism , but they may cause other health problems . some studies linking cured meats to cancer have suggested that these preservatives may be the culprit . meanwhile , antioxidant preservatives prevent the chemical changes that can give food an off-flavor or color . smoke has been used to preserve food for millennia because some of the aromatic compounds in wood smoke are antioxidants . combining smoking with salting was an effective way of preserving meat before refrigeration . for antioxidant activity without a smoky flavor , there are compounds like bht and tocopherol , better known as vitamin e. like the compounds in smoke , these sop up free radicals and stave off rancid flavors that can develop in foods like oils , cheese , and cereal . other antioxidants like citric acid and ascorbic acid help cut produce keep its color by thwarting the enzyme that causes browning . some compounds like sulfites can multitask . they 're both antimicrobials and antioxidants . sulfites may cause allergy symptoms in some people , but most antioxidant preservatives are generally recognized as safe . so should you be worried about preservatives ? well , they 're usually near the end of the ingredients list because they 're used in very small amounts determined by the fda to be safe . nevertheless , some consumers and companies are trying to find alternatives . packaging tricks , like reducing the oxygen around the food can help , but without some kind of chemical assistance , there are very few foods that can stay shelf stable for long .
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how do they help keep food edible and are they safe ? there are two major factors that cause food to go bad : microbes and oxidation . microbes like bacteria and fungi invade food and feed off its nutrients .
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describe two primary pathways for food degradation , and name a few preservatives that can combat each .
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the sight of mistletoe may either send you scurrying , or if you have your eye on someone , awaiting an opportunity beneath its snow white berries , but how did the festive christmas tradition of kissing under mistletoe come about ? the long-lived custom intertwines the mythology and biology of this intriguing plant . there are more than 1,000 species of mistletoe , which grows the world over . in fact , the ancient europeans were so captivated by the plant 's unusual growth habits that they included it in their legends and myths . in ancient rome , pliny the elder described how the druid priesthood in ancient england believed that mistletoe was a plant dropped down from heaven by the gods . that explained its unlikely position amongst the high branches of certain trees . they also believed it had powers of healing and bestowing fertility . meanwhile , scandinavian legend told of the plant 's mystical qualities in the story of the god baldr and his adoring mother frigg , goddess of love , marriage , and fertility . frigg loved her son so much that she commanded every plant , animal , and inanimate object to vow they 'd never harm him . in her fervor , however , she overlooked the mistletoe . the mischievous god loki realized this oversight and pierced baldr 's heart with an arrow carved from a mistletoe branch . frigg cried tears of such sadness that they formed the mistletoe 's pearly berries , making the other gods pity her and agree to resurrect baldr . hearing the news , frigg became so overjoyed that she transformed the mistletoe from a symbol of death into one of peace and love . she mandated a one-day truce for all fights , and that everyone embrace beneath its branches when they passed to spread more love into the world . in the 17th century , british colonists arriving in the new world found a different , but very similar looking , species of mistletoe . they applied it to these tales of magic , fertility , and love , spreading the mistletoe-hanging tradition from europe into america . by the 18th century , people in britain had turned this into a christmas tradition , but this custom comes down to more than just human imagination . all of it was inspired by the plant 's intriguing biology . we see mistletoe as a festive decoration , but draped on tree boughs in the wild , it 's known as a partly parasitic plant . mistletoe relies on modified roots called haustoria that penetrate the tree bark and siphon off the water and minerals trees carry up their trunks to colonize nearby trees with its seeds , mistletoe depends on birds and other creatures to do the dispersing . birds that eat the mistletoe 's sticky white berries sometimes get rid of the gluey seeds by wiping them off onto tree bark . or with a bit of luck , they excrete the indigestible seed onto a tree where it germinates and starts to grow . with its resilience and foliage that stays lush even while the surrounding trees lose their leaves , you can see why mistletoe captivated our superstitious ancestors . they saw these as signs of the plant 's magical qualities and fertility . even today , the mistletoe inspires wonder with the diversity of wildlife it supports . more than just a parasite , it 's also known as a keystone species . it 's eaten by a diversity of animals , including deer , elk , squirrels , chipmunks , porcupines , robins , bluebirds , morning doves , and the butterfly genus delias . some mistletoe species produce dense bushes , which are excellent nesting locations for a variety of birds . and despite their parasitic relationship with trees , mistletoes can also help other plants . for instance , juniper sprouts near mistletoe to benefit from the visiting berry-eating birds . through the many benefits it provides , mistletoe influences diversity , and allows ecosystems to flourish . you might even say that for this iconic plant , life imitates legend . in the wild , mistletoe has the power to bring things together , and in our own traditions , we see that happening , too .
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in the 17th century , british colonists arriving in the new world found a different , but very similar looking , species of mistletoe . they applied it to these tales of magic , fertility , and love , spreading the mistletoe-hanging tradition from europe into america . by the 18th century , people in britain had turned this into a christmas tradition , but this custom comes down to more than just human imagination .
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why is keeping the leaves in winter such an outstanding feature among plants in the northern hemisphere where the mistletoe tradition began ?
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we have some good reasons to completely switch over to solar power . it 's cheaper in many cases , and definitely more sustainable than our dependance on traditional power plants that use resources like coal , which will eventually run out . so why do n't we replace these traditional plants with solar energy ? because there 's one factor that makes solar power very unpredictable : cloud cover . as the sun 's rays move towards earth , some get absorbed by the earth 's atmosphere , some are reflected back into outer space , but the rest make it to the earth 's surface . the ones that are n't deviated are called direct irradiance . the ones that are deflected by clouds are called diffuse irradiance . and those rays that first get reflected by a surface , like a nearby building , before reaching the solar energy system are called reflected irradiance . but before we can examine how clouds affect the sun 's rays and electricity production , let 's see how these solar energy systems work . first up , we have solar towers . these are made up of a central tower surrounded by a huge field of mirrors that track the sun 's path and focus only the direct rays onto a single point on the tower , kind of like an eager beachgoer . the heat generated by these rays is so immense that it can be used to boil water producing steam that drives a traditional turbine , which makes electricity . but when we say solar energy systems , we 're usually talking about photovoltaics , or solar panels , which are the systems most commonly used to generate solar power . in solar panels , photons from the sun 's rays hit the surface of a panel , and electrons are released to get an electric current going . solar panels can use all types of irradiance , while solar towers can only use direct irradiance , and this is where clouds become important because depending on their type and location relative to the sun , they can either increase or decrease the amount of electricity produced . for instance , even a few cumulus clouds in front of the sun can reduce the electricity production in solar towers to almost zero because of this dependence on direct rays . in solar panels , those clouds would decrease energy output as well , though not as much because solar panels can use all types of irradiance . however , all this depends on the clouds exact positioning . due to reflection , or a particular phenomeon called mie scattering , the sun 's rays can actually be focused forward by clouds to create a more than 50 % increase in the solar irradiance reaching a solar panel . if this potential increase is n't accounted for , it could damage the solar panel . why does this matter ? well , you would n't want this lesson to stop just because a cloud passed over the panel on your roof . in solar towers , huge tanks of molten salt or oil can be used to store any excess heat and use it when needed , so that 's how they manage the problem of fluctuating solar irradiance to smooth out electricity production . but in the case of solar panels , there currently is n't any way to affordably store extra energy . that 's where traditional power plants come in because to correct for any fluctuations in these solar powered plants , extra electricity from traditional sources always needs to be available . but then why are n't these tradtional power plants just used as a backup , instead of us humans depending on them as our main sources of energy ? because it 's impossible for an employee at a coal fired or a nuclear plant to turn a knob to produce more or less electricity depending on how many clouds there are in the sky . the response time would simply be too slow . instead , to accommodate these fluctuations , some extra electricity from traditional power plants is always being produced . on clear sky days , that extra electricity might be wasted , but when cloudy skies prevail , it 's what fills the gap . this is what we currently depend on for a constant supply of energy . for this reason , a lot of researchers are interested in forcasting the motion and formation of clouds through satellite images or cameras that look up at the sky to maximize the energy from solar power plants and minimize energy waste . if we could accomplish that , you 'd be able to enjoy this video powered solely by the sun 's rays , no matter what the weather , although if the sun is shining , you may be tempted to venture outside to go and do a different kind of cloud gazing .
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the heat generated by these rays is so immense that it can be used to boil water producing steam that drives a traditional turbine , which makes electricity . but when we say solar energy systems , we 're usually talking about photovoltaics , or solar panels , which are the systems most commonly used to generate solar power . in solar panels , photons from the sun 's rays hit the surface of a panel , and electrons are released to get an electric current going .
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is solar energy the solution ?
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imagine that day by day , your field of vision becomes slightly smaller , narrowing or dimming until eventually you go completely blind . we tend to think of blindness as something you 're born with , but in fact , with many diseases like retinitis pigmentosa and usher syndrome , blindness can start developing when you 're a kid , or even when you 're an adult . both of these rare genetic diseases affect the retina , the screen at the back of the eye that detects light and helps us see . now imagine if the eye could regenerate itself so that a blind person could see again . to understand if that 's possible , we need to grasp how the retina works and what it has to do with a multitalented creature named the zebrafish . the human retina is made of different layers of cells , with special neurons that live in the back of the eye called rod and cone photoreceptors . photoreceptors convert the light coming into your eye into signals that the brain uses to generate vision . people who have usher syndrome and retinitis pigmentosa experience a steady loss of these photoreceptors until finally that screen in the eye can no longer detect light nor broadcast signals to the brain . unlike most of your body 's cells , photoreceptors do n't divide and multiply . we 're born with all the photoreceptors we 'll ever have , which is why babies have such big eyes for their faces and part of why they 're so cute . but that is n't the case for all animals . take the zebrafish , a master regenerator . it can grow back its skin , bones , heart and retina after they 've been damaged . if photoreceptors in the zebrafish retina are removed or killed by toxins , they just regenerate and rewire themselves to the brain to restore sight . scientists have been investigating this superpower because zebrafish retina are also structured very much like human retina . scientists can even mimic the effects of disorders like usher syndrome or retinitis pigmentosa on the zebrafish eye . this allows them to see how zebrafish go about repairing their retinas so they might use similar tactics to fix human eyes one day , too . so what 's behind the zebrafish 's superpower ? the main players are sets of long cells that stretch across the retina called müller glia . when the photoreceptors are damaged , these cells transform , taking on a new character . they become less like müller cells and more like stem cells , which can turn into any kind of cell . then these long cells divide , producing extras that will eventually grow into new photoreceptors , travel to the back of the eye and rewire themselves into the brain . and now some researchers even think they 've found the key to how this works with the help of one of two chemicals that create activity in the brain called glutamate and aminoadipate . in mouse eyes , these make the müller glia divide and transform into photoreceptors , which then travel to the back of the retina , like they 're replenishing a failing army with new soldiers . but remember , none of this has happened in our retinas yet , so the question is how do we trigger this transformation of the müller glia in the human eye ? how can we fully control this process ? how do photoreceptors rewire themselves into the retina ? and is it even possible to trigger this in humans ? or has this mechanism been lost over time in evolution ? until we tease apart the origins of this ability , retinal regeneration will remain a mysterious superpower of the common zebrafish .
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but that is n't the case for all animals . take the zebrafish , a master regenerator . it can grow back its skin , bones , heart and retina after they 've been damaged .
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zebrafish really are master regenerators – they regenerate skin , bones , and heart if they 're damaged ! what other diseases or injuries might with be able to treat by studying the zebrafish 's regenerative abilities ?
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translator : andrea mcdonough reviewer : bedirhan cinar i would like to introduce you to one of the most amazing scientists who have ever lived . so famous , that more places on earth have been named after him than any human being . so famous , that president thomas jefferson said he was the most important scientist he ever met . and simon bolivar called him the true discoverer of south america . on the 100th anniversary of his birth , every story on the front page of < i > the new york times < /i > was written about him . who is this scientist and what did he do that was so extraordinary ? his name is alexander von humboldt . never heard of him ? most people have n't . his name has been lost in history , but here is what he did . alexander von humboldt started as a practicing geologist , but when an inheritance allowed him the freedom to travel , he began an incredible , five-year scientific journey through south america , mexico , and cuba . from 1799 to 1804 , von humboldt and his botonist partner , aime bonpland , traveled through the jungles of venezuela , made detailed drawings of inca ruins while exploring the mountains of peru , and traversed the breadth of mexico and cuba . he explored the length of the orinoco river in venezuela . this 1700 mile portion of the trip was filled with danger , disease , and fantastic new discoveries . for example , von humboldt was the first explorer to witness the preparation of the curare plant for poison arrows . he recognized the importance of the cinchona tree , whose bark contains quinine , which is a malaria cure , and discovered the ocean current , which limits rainfall on the coast of peru , later named the humboldt current . he discovered and described many new species of plants and animals , including the electric eel . in ecuador , he climbed the one of the highest volcanoes , chimborazo , so that he could record air pressure , something no one had ever done at this altitude . the entire journey covered over 24,000 miles , the same distance as the circumference of the earth . along the way , he took measurements about the shape of the land , its temperature , the air pressure , and the strength of magnetic fields . by connecting places of identical temperatures , he created contour maps with lines of similar temperatures , which he called `` isotherms '' . because humboldt invented these maps , scientists began to see patterns in the life and the types of life present in certain places , and he became a pioneer in the visual presentation of scientific data . these discoveries and measurements were critical to what made him such an important scientist . until humboldt , scientists who described new plants and animals did not clearly see the crucial connection between living things and the places in which they lived , called habitats . they did not appreciate the role of the environment on the diversity of life . humboldt discovered and understood the importance of these connections . because of this , he is considered the founder of biogeography . he also developed a theory called the `` unity of nature , '' which shows the interconnectedness of all nature . this knowledge plays a vital role in the preservation and protection of our habitat . his book , < i > cosmos < /i > , describes this theory and is still in print today . as celebrated a scientist as he was , von humboldt was also generous , thus serving another role in the world . he was the mentor and teacher to younger scientists . in fact , just recently it was discovered the crucial role that humboldt played in the work of his most famous pen-pal , charles darwin . a young darwin read humboldt extensively and wrote in his diary while on the beagle , `` i am at present fit only to read humboldt . he , like another sun , illuminates everything i behold . '' today , although humboldt is known and revered by a small community of scientists , he is almost totally forgotten by many of us . alexander von humboldt 's influence is apparent everywhere and in every scientific discipline . he is , perhaps , the most important forgotten man of science . but he does n't have to be , because if you remember him , perhaps his influence will be celebrated .
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who is this scientist and what did he do that was so extraordinary ? his name is alexander von humboldt . never heard of him ?
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briefly describe the regions that alexander von humboldt explored . what type of measurements did he take in these places ?
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translator : jessica ruby reviewer : brian greene could human civilization eventually spread across the whole milky way galaxy ? could we move beyond our small blue planet to establish colonies in the multitude of star systems out there ? this question 's a pretty daunting one . there are around 300 billion stars in the galaxy , which is about 160,000 light-years across . so far we 've sent a single spacecraft outside our solar system , trudging along at 0.006 % of the speed of light . at that rate , it would take over 2.5 billion years just to get from one end of the galaxy to the other . and then there 's the question of human survival . the gulf between stars is simply enormous . we could n't live sustainably on most planets , and we require a lot of resources to stay alive . and yet , decades ago , scholars found that it 's theoretically possible to not just spread human civilization across the galaxy , but to do so quite quickly , without breaking any known laws of physics . their idea is based on the work of a mathematician named john von neumann , who designed on paper machines that could self-replicate and create new generations of themselves . these would later come to be known as von neumann machines . in the context of space exploration , von neumann machines could be built on earth and launched into space . there , the self-sufficient machines would land on distant planets . they would then mine the available resources and harvest energy , build replicas of themselves , launch those to the nearest planets , and continue the cycle . the result is the creation of millions of probes spreading outwards into the universe like a drop of ink in a fishbowl . scholars crunched the numbers and found that a single von neumann machine traveling at 5 % of the speed of light should be able to replicate throughout our galaxy in 4 million years or less . that may sound like a long time , but when you consider that our universe is 14 billion years old , on a cosmic scale , it 's incredibly fast - the equivalent of about 2.5 hours in an entire year . creating von neumann machines would require a few technologies we do n't have yet , including advanced artificial intelligence , miniaturization , and better propulsion systems . if we wanted to use them to spread actual humans throughout the galaxy , we would need yet another technological leap - the ability to artificially grow biological organisms and bodies using raw elements and genetic information . regardless , if in the last billion years an alien civilization created such a machine and set it multiplying its way toward us , our galaxy would be swarming with them by now . so then where are all these machines ? some astronomers , like carl sagan , say that intelligent aliens would n't build self-replicating machines at all . they might hurtle out of control , scavenging planets to their cores in order to keep replicating . others take the machines absence as proof that intelligent alien civilizations do n't exist , or that they go extinct before they can develop the necessary technologies . but all this has n't stopped people from imagining what it would be like if they were out there . science fiction author david brin writes about a universe in which many different von neumann machines exist and proliferate simultaneously . some are designed to greet young civilizations , others to locate and destroy them before they become a threat . in fact , in brin 's story `` lungfish , '' some von neumann machines are keeping a close watch over the earth right now , waiting for us to reach a certain level of sophistication before they make their move . for now , all we have is curiosity and theory . but the next time you look at the night sky , consider that billions of self-replicating machines could be advancing between stars in our galaxy right now . if they exist , one of them will eventually land on earth , or maybe , just maybe , they 're already here .
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their idea is based on the work of a mathematician named john von neumann , who designed on paper machines that could self-replicate and create new generations of themselves . these would later come to be known as von neumann machines . in the context of space exploration , von neumann machines could be built on earth and launched into space . there , the self-sufficient machines would land on distant planets .
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alien von neumann machines :
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you 're standing at the ready inside the goal when suddenly , you feel an intense itch on the back of your head . we 've all experienced the annoyance of an inconvenient itch , but have you ever pondered why we itch in the first place ? the average person experiences dozens of individual itches each day . they can be triggered by all sorts of things , including allergic reactions , dryness , and even some diseases . and then there are the mysterious ones that pop up for no reason at all , or just from talking about itching . you 're scratching your head right now , are n't you ? anyhow , let 's take one of the most common sources : bug bites . when a mosquito bites you , it releases a compound into your body called an anticoagulant that prevents your blood from clotting . that compound , which we 're mildly allergic to , triggers the release of histamine , a chemical that makes our capillaries swell . this enables increased blood flow , which helpfully accelerates the body 's immune response to this perceived threat . that explains the swelling , and it 's the same reason pollen can make your eyes puff up . histamine also activates the nerves involved in itching , which is why bug bites make you scratch . but the itchy sensation itself is n't yet fully understood . in fact , much of what we do know comes from studying the mechanics of itching in mice . researchers have discovered that itch signals in their skin are transmitted via a subclass of the nerves that are associated with pain . these dedicated nerves produce a molecule called natriuretic polypetide b , which triggers a signal that 's carried up the spinal cord to the brain , where it creates the feeling of an itch . when we scratch , the action of our fingernails on the skin causes a low level pain signal that overrides the itching sensation . it 's almost like a distraction , which creates the sensation of relief . but is there actually an evolutionary purpose to the itch , or is it simply there to annoy us ? the leading theory is that our skin has evolved to be acutely aware of touch so that we 're equipped to deal with risks from the outside world . think about it . our automatic scratching response would dislodge anything harmful that 's potentially lurking on our skin , like a harmful sting , a biting insect , or the tendrils of a poisonous plant . this might explain why we do n't feel itching inside our bodies , like in our intestines , which is safe from these external threats , though imagine how maddening that would be . in some people , glitches in the pathways responsible for all of this can cause excessive itching that can actually harm their health . one extreme example is a psychological condition called delusory parasitosis where people believe their bodies are infested with mites or fleas scurrying over and under their skin , making them itch incessantly . another phenomenon called phantom itching can occur in patients who 've had amputations . because this injury has so severely damaged the nervous system , it confuses the body 's normal nerve signaling and creates sensations in limbs that are no longer there . doctors are now finding ways to treat these itching anomalies . in amputees , mirrors are used to reflect the remaining limb , which the patient scratches . that creates an illusion that tricks the brain into thinking the imaginary itch has been satisfied . oddly enough , that actually works . researchers are also searching for the genes involved in itching and developing treatments to try and block the pathway of an itch in extreme cases . if having an unscratchable itch feels like your own personal hell , dante agreed . the italian poet wrote about a section of hell where people were punished by being left in pits to itch for all eternity .
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the leading theory is that our skin has evolved to be acutely aware of touch so that we 're equipped to deal with risks from the outside world . think about it . our automatic scratching response would dislodge anything harmful that 's potentially lurking on our skin , like a harmful sting , a biting insect , or the tendrils of a poisonous plant .
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why do you think there are so many things in the world that make us itch ?
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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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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 .
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which famous poet wrote a poem called 'the cloud ' :
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in well-meaning attempts to boost our confidence ahead of challenging moments , people often try to draw our attention to our strengths : our intelligence , our competence , our experience . but this can – curiously – have some awkward consequences . there ’ s a type of under-confidence that arises specifically when we grow too attached to our own dignity and become anxious around any situation that might seem to threaten it . we hold back from challenges in which there is any risk of ending up looking ridiculous which comprises , of course , almost all the most interesting situations . in a foreign city , we might grow reluctant to ask anyone to guide us to the nice bars , because they might think us an ignorant , pitiable , lost tourist . we might long to kiss someone but never let on out of a fear that they could dismiss us as a predatory loser . or at work , we don ’ t apply for a promotion , in case the senior management deems us delusionally arrogant . in a concerted bid never to look foolish , we don ’ t venture very far from our cocoon , and thereby – from time to time at least – miss out on the best opportunities of our lives . at the heart of our under-confidence is a skewed picture of how dignified it is normal for a person to be . we imagine that it might be possible , after a certain age , to place ourselves beyond mockery . we trust that it 's an option to lead a good life without regularly making a complete idiot of ourselves . one of the most charming books ever written in early modern europe is called 'in praise of folly ' by the dutch scholar and philosopher , erasmus . in its pages , erasmus advances a hugely liberating argument . in a warm tone , he reminds us that everyone , however important and learned they might be , is a fool . no one is spared , not even the author . however well-schooled he himself was , erasmus remained – he insists – as much of a nitwit as anyone else : his judgement is faulty , his passions get the better of him , he is prey to superstition and irrational fear , he is shy whenever he has to meet new people , he drops things at elegant dinners . this is deeply cheering , for it means that our own repeated idiocies do n't have to exclude us from the best company . looking like a prick , making blunders and doing bizarre things in the night doesn ’ t render us unfit for society ; it just makes us a bit more like the greatest scholar of the northern european renaissance . there ’ s a similarly uplifting message to be pulled from the work of pieter brueghel . his central work , 'the dutch proverbs , ' presents a comically disenchanted view of human nature . everyone , he suggests , is pretty much deranged : here ’ s a man throwing his money into the river ; there ’ s a soldier squatting on the fire and burning his trousers ; someone is intently bashing his head against a brick wall ; someone else is biting a pillar . importantly , the painting is not an attack on just a few unusually awful people -- it ’ s a picture of parts of all of us . brueghel ’ s and erasmus ’ s work proposes that the way to greater confidence isn ’ t to reassure ourselves of our own dignity -- it ’ s to grow at peace with the inevitable nature of our ridiculousness . we are idiots now , we have been idiots in the past , and we will be idiots again in the future ... and that 's ok . there aren ’ t any other available options for human beings to be . once we learn to see ourselves as already , and by nature , foolish , it really doesn ’ t matter so much if we do one more thing that might make us look a bit stupid . the person we try to kiss could indeed think us ridiculous . the individual we asked directions from in a foreign city might regard us with contempt . but if these people did so , it wouldn ’ t be news to us -- they would only be confirming what we had already gracefully accepted in our hearts long ago : that we , like them – and every other person on the earth – are a nitwit . the risk of trying and failing would have its sting substantially removed . a fear of humiliation would no longer stalk us in the shadows of our minds . we would grow free to give things a go by accepting that failure was the acceptable norm . and every so often , amidst the endless rebuffs we ’ d have factored in from the outset , it would work : we ’ d get a kiss , we ’ d make a friend , we ’ d get a raise . the road to greater confidence begins with a ritual of telling oneself solemnly every morning before heading out for the day , that one is a muttonhead , a cretin , a dumbbell and an imbecile . one or two more acts of folly should , thereafter , not matter very much at all .
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we hold back from challenges in which there is any risk of ending up looking ridiculous which comprises , of course , almost all the most interesting situations . in a foreign city , we might grow reluctant to ask anyone to guide us to the nice bars , because they might think us an ignorant , pitiable , lost tourist . we might long to kiss someone but never let on out of a fear that they could dismiss us as a predatory loser .
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according to this video , why does it sometimes hurt us to be reminded of our strengths ?
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how did adolf hitler , a tyrant who orchestrated one of the largest genocides in human history , rise to power in a democratic country ? the story begins at the end of world war i . with the successful allied advance in 1918 , germany realized the war was unwinnable and signed an armistice ending the fighting . as its imperial government collapsed , civil unrest and worker strikes spread across the nation . fearing a communist revolution , major parties joined to suppress the uprisings , establishing the parliamentary weimar republic . one of the new government 's first tasks was implementing the peace treaty imposed by the allies . in addition to losing over a tenth of its territory and dismantling its army , germany had to accept full responsibility for the war and pay reparations , debilitating its already weakened economy . all this was seen as a humiliation by many nationalists and veterans . they wrongly believed the war could have been won if the army had n't been betrayed by politicians and protesters . for hitler , these views became obsession , and his bigotry and paranoid delusions led him to pin the blame on jews . his words found resonance in a society with many anti-semitic people . by this time , hundreds of thousands of jews had integrated into german society , but many germans continued to perceive them as outsiders . after world war i , jewish success led to ungrounded accusations of subversion and war profiteering . it can not be stressed enough that these conspiracy theories were born out of fear , anger , and bigotry , not fact . nonetheless , hitler found success with them . when he joined a small nationalist political party , his manipulative public speaking launched him into its leadership and drew increasingly larger crowds . combining anti-semitism with populist resentment , the nazis denounced both communism and capitalism as international jewish conspiracies to destroy germany . the nazi party was not initially popular . after they made an unsuccessful attempt at overthrowing the government , the party was banned , and hitler jailed for treason . but upon his release about a year later , he immediately began to rebuild the movement . and then , in 1929 , the great depression happened . it led to american banks withdrawing their loans from germany , and the already struggling german economy collapsed overnight . hitler took advantage of the people 's anger , offering them convenient scapegoats and a promise to restore germany 's former greatness . mainstream parties proved unable to handle the crisis while left-wing opposition was too fragmented by internal squabbles . and so some of the frustrated public flocked to the nazis , increasing their parliamentary votes from under 3 % to over 18 % in just two years . in 1932 , hitler ran for president , losing the election to decorated war hero general von hindenburg . but with 36 % of the vote , hitler had demonstrated the extent of his support . the following year , advisors and business leaders convinced hindenburg to appoint hitler as chancellor , hoping to channel his popularity for their own goals . though the chancellor was only the administrative head of parliament , hitler steadily expanded the power of his position . while his supporters formed paramilitary groups and fought protestors in streets . hitler raised fears of a communist uprising and argued that only he could restore law and order . then in 1933 , a young worker was convicted of setting fire to the parliament building . hitler used the event to convince the government to grant him emergency powers . within a matter of months , freedom of the press was abolished , other parties were disbanded , and anti-jewish laws were passed . many of hitler 's early radical supporters were arrested and executed , along with potential rivals , and when president hindenburg died in august 1934 , it was clear there would be no new election . disturbingly , many of hitler 's early measures did n't require mass repression . his speeches exploited people 's fear and ire to drive their support behind him and the nazi party . meanwhile , businessmen and intellectuals , wanting to be on the right side of public opinion , endorsed hitler . they assured themselves and each other that his more extreme rhetoric was only for show . decades later , hitler 's rise remains a warning of how fragile democratic institutions can be in the face of angry crowds and a leader willing to feed their anger and exploit their fears .
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by this time , hundreds of thousands of jews had integrated into german society , but many germans continued to perceive them as outsiders . after world war i , jewish success led to ungrounded accusations of subversion and war profiteering . it can not be stressed enough that these conspiracy theories were born out of fear , anger , and bigotry , not fact .
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how was the result of world war i used by hitler and the nazis to seize power and gain support amongst the german people ?
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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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these difficulties are more widespread and varied than commonly imagined . dyslexia affects up to one in five people . it occurs on a continuum .
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how many people are affected by dyslexia ?
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translator : andrea mcdonough reviewer : bedirhan cinar why do we see illusions ? i 'm going to tell you about some of my research , where i provided evidence for a different kind of hypothesis than the one that might be in the book on your coffee stand . alright , so let 's look at one of the illusions here . and this is a stand-in for many , many kinds of illusions that are explained by this hypothesis . i 'm just going to walk through it for this particular one . as usual in these things , these two lines are , in fact , parallel , but you perceive them to bow outwards at their centers . at the center where those radial lines are , it 's wider in your visual field than the parts above and below . and this is remarkable , because it 's a remarkably simple stimulus . it 's just a bunch of straight lines . why should one of the most complicated objects in the universe be unable to render this incredibly simple image ? when you want to answer questions like this , you need to ask , well , what might this mean to your brain ? and what your brain is going to think this is , is not some lines on a page . your brain has evolved to handle the kinds of natural stimuli that it encounters in real life . so when does the brain encounter stimuli like this ? well , it seems a bit odd , but in fact , you 've been encountering this stimulus all day long . whenever you move , whenever you move forward , in particular . when you move forward , you get optic flow , flowing outwards in your visual field , like when the enterprise goes into warp . all of these objects flow outwards and they leave trails , or blur lines , on your retina . they 're activating mini-neurons all in a row . so , this is a version of what happens in real life and this another version of what happens in real life all the time . in fact , cartoonists know about this . they put these blur lines in their cartoons and it means to your brain : motion . now , it 's not that in real life you see blur lines . the point is that it 's the stimulus at the back of your eye that has these optic blurs in them , and that 's what tells your brain that you 're moving . when you move forward , your eyes fixate like cameras , like snapshot cameras , it fixates , it fixates , little ( snapshot sound ) camera shots , and each time it fixates when you 're moving forward , you get all this flowing outwards . so when you take a fixation , you end up with this weird optic blur stuff , and it tells you the direction you 're moving . alright , that 's half the story . that 's what this stimulus means . it means that your brain thinks , when it 's looking at the first image , that you 're actually on your way , moving towards the center . it still does n't explain why you should perceive these straight lines as bowed outwards . to understand the rest of the story , you have to understand that our brains are slow . what you would like is that when light hits your eye , then -- ping ! -- immediately you have a perception of what the world is like . but it does n't work that way . it takes about a tenth of a second for your perception to be created . and a tenth of a second does n't sound very long , but it 's a long time in normal behaviors . if you 're moving just at one meter per second , which is fairly slow , then in a tenth of second , you 've moved 10 centimeters . so if you did n't correct for this delay , then anything that you perceived to be within 10 centimeters of you , by the time you perceived it , you would have bumped into it or just passed it . and of course , this is going to be much worse -- ( laughter ) it 's going to be much worse in a situation like this . your perception is behind . what you want is that your perception should look like this . you want your perceptions at any time t to be of the world at time t. but the only way your brain can do that , is that it has to , instead of generating a perception of the way the world was when light hit your retina , it has to do something fancier . it ca n't passively respond and create a best guess , it has to create a best guess about the next moment . what will the world look like in a tenth of a second ? build a perception of that , because by the time your perception of the near future occurs in your brain , the near future will have arrived and you 'll have a perception of the present , which is what you want . in my research , i provided a lot of evidence -- and there 's other research areas that have provided evidence -- that the brain is filled with mechanisms that try to compensate for its slowness . and i 've shown that huge swaths of illusions are explained by this , this just being one example . but let me finish by saying , how exactly does this explain this particular example ? so , the question , really , we have to ask is : how do those two vertical lines in that first stimulus , how do they change in the next moment were i moving towards the center , that all those optical lines are suggesting that i 'm moving . what happens to them ? well , let 's imagine . imagine you 've got a doorway . you 've got a doorway . imagine it 's a cathedral doorway , to make it more concrete -- it 'll be helpful in a second . when you 're very far away from it , the sides are perfectly parallel . but now imagine what happens when you get closer . it all flows outwards in your visual field , flowing outwards . but when you 're really close -- imagine the sides of the doorway are here and here , but if you look up at this cathedral doorway and do your fingers like this , the sides of the doorway are going up , like railroad tracks in the sky . what started off as two parallel lines , in fact , bows outwards at eye level , and does n't go outwards nearly as much above . so in the next moment , you have a shape that 's more like this next picture . the projective geometry -- that is , the way the things project , in fact , change in this way in the next moment . so when you have a stimulus like this , well , your brain has no problem , there 's just two vertical lines and no cues that there 'll be a change in the next moment , so just render it as it is . but if you add cues -- and this is just one of many kinds of cues that can lead to these kinds of illusions , this very strong optic blur cue -- then you 're going to perceive instead exactly how it will appear in the next moment . all of our perceptions are always trying to be about the present , but you have to perceive the future to , in fact , perceive the present . and these illusions are failed perceptions of the future , because they 're just static images on the page , they 're not changing like in real life . and let me just end by showing one illusion here . if i can , i 'll quickly show two . this one 's fun . if you just fixate at the middle there , and make stabbing motions with your head , looming towards it like this . everybody do that . make short , stabbing motions . because i 've added blur to these optic flow lines , your brain says , `` they 're probably already moving , that 's why they 're blurry . '' when you do it , they should be bursting out in your visual field faster than they should . they should n't be moving that much . and a final one i 'll just leave in the background is this . here are the cues of motion , the kinds of cues that you get on your retina when things are moving . you do n't have to do anything -- just look at it . raise your hand if things are moving when they should n't be . it 's weird , right ? but what you have now are the cues that , from your brain 's point of view , you have the stimulus on your eyes , like , `` oh , these things are moving . '' render a perception of what they 'll do in the next moment -- they should be moving and they should have shifted . alright , thank you very much . ( applause )
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to understand the rest of the story , you have to understand that our brains are slow . what you would like is that when light hits your eye , then -- ping ! -- immediately you have a perception of what the world is like .
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when light hits your eye , how long does it take for your brain to perceive what you are actually seeing ?
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it 's so obvious that it 's practically proverbial . you ca n't unboil an egg . well , it turns out you can , sort of . what thermal energy does to the eggs ' molecules , mechanical energy can undo . eggs are mostly made of water and proteins . the proteins start off folded up into intricate shapes , held together by weak chemical bonds . adding heat disrupts those bonds , allowing the proteins to unfold , uncoil , unwind and wiggle freely . this process is called denaturing . the newly liberated proteins bump up against their neighbors and start to form new bonds with each other , more and more as the heat increases , until finally , they 're so entangled that they gel into a solid mass , a boiled egg . that entanglement might look permanent , but it 's not . according to a chemical idea called the principle of microscopic reversibility , anything that happens , like egg proteins seizing up , can theoretically unhappen if you retrace your steps . but adding more heat will tangle the proteins further , and cooling them down will only freeze them , so here 's the trick : spin them around ridiculously fast . i 'm not kidding . here 's how it works . first , scientists dissolve boiled egg whites in water with a chemical called urea , a small molecule that acts as a lubricant , coating the proteins ' long strands and making it easier for them to glide past each other . then , they spin that solution in a glass tube at a breakneck 5000 rotations per minute , making the solution spread out into a thin film . here 's the key part . the solution nearest the wall spins faster than the solution closer to the middle . that difference in velocity creates sheer stresses that repeatedly stretch and contract the proteins until eventually they snap back into their native shapes and stay there . by the time the centrifuge stops spinning , the egg white is back in its original unboiled state . this technique works with all sorts of proteins . bigger , messier proteins can be more resistant to being pulled apart , so scientists attach a plastic bead to one end that adds extra stress and encourages it to fold up first . this unboiling method wo n't work with a whole egg in its shell since the solution has to spread throughout a cylindrical chamber . but the applications go way beyond uncooking your breakfast , anyhow . many pharmaceuticals consist of proteins that are extremely expensive to produce , partly because they get stuck in tangled up aggregates , just like cooked egg whites and have to be untangled and refolded before they can do their jobs . this spinning technique has the potential to be an easier , cheaper and quicker method than other ways to refold proteins , so it may allow new drugs to be made available to more people faster . and there 's one more thing you need to keep in mind before trying to uncook all of your food . boiling an egg is actually an unusual cooking process because even though it changes the way proteins are shaped and bound together , it does n't actually change their chemical identity . most types of cooking are more like the famous maillard reaction , which makes chemical changes that turn sugars and proteins into delicious caramel crunchiness and are a lot harder to undo . so you might be able to unboil your egg , but i 'm sorry to say you ca n't unfry it ... yet .
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first , scientists dissolve boiled egg whites in water with a chemical called urea , a small molecule that acts as a lubricant , coating the proteins ' long strands and making it easier for them to glide past each other . then , they spin that solution in a glass tube at a breakneck 5000 rotations per minute , making the solution spread out into a thin film . here 's the key part .
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in the vortex fluid device , the solution closet to the walls of the tube :
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the presidency of the united states of america is often said to be one of the most powerful positions in the world . but of all the u.s. presidents accused of misusing that power , only one has left office as a result . does richard nixon deserve to be remembered for more than the scandal that ended his presidency ? find out as we put this disgraced president 's legacy on trial in history vs. richard nixon . `` order , order . now , who 's the defendant today , some kind of crook ? '' `` cough . no , your honor . this is richard milhous nixon , the 37th president of the united states , who served from 1969 to 1974 . '' `` hold on . that 's a weird number of years for a president to serve . '' `` well , you see , president nixon resigned for the good of the nation and was pardoned by president ford , who took over after him . '' `` he resigned because he was about to be impeached , and he did n't want the full extent of his crimes exposed . '' `` and what were these crimes ? '' `` your honor , the watergate scandal was one of the grossest abuses of presidential power in history . nixon 's men broke into the democratic national committee headquarters to wiretap the offices and dig up dirt on opponents for the reelection campaign . '' `` cough it was established that the president did not order this burglary . '' `` but as soon as he learned of it , he did everything to cover it up , while lying about it for months . '' `` uh , yes , but it was for the good of the country . he did so much during his time in office and could have done so much more without a scandal jeopardizing his accomplishments . '' `` uh , accomplishments ? '' `` yes , your honor . did you know it was president nixon who proposed the creation of the environmental protection agency , and signed the national environmental policy act into law ? not to mention the endangered species act , marine mammal protection act , expansion of the clean air act . '' `` sounds pretty progressive of him . '' `` progressive ? hardly . nixon 's presidential campaign courted southern voters through fear and resentment of the civil rights movement . '' `` speaking of civil rights , the prosecution may be surprised to learn that he signed the title ix amendment , banning gender-based discrimination in education , and ensured that desegregation of schools occurred peacefully , and he lowered the voting age to 18 , so that students could vote . '' `` he did n't have much concern for students after four were shot by the national guard at kent state . instead , he called them bums for protesting the vietnam war , a war he had campaigned on ending . '' `` but he did end it . '' `` he ended it two years after taking office . meanwhile , his campaign had sabotaged the previous president 's peace talks , urging the south vietnamese government to hold out for supposedly better terms , which , i might add , did n't materialize . so , he protracted the war for four years , in which 20,000 more u.s. troops , and over a million more vietnamese , died for nothing . '' `` hmm , a presidential candidate interfering in foreign negotiations -- is n't that treason ? '' `` it is , your honor , a clear violation of the logan act of 1799 . '' `` uh , i think we 're forgetting president nixon 's many foreign policy achievements . it was he who normalized ties with china , forging economic ties that continue today . '' `` are we so sure that 's a good thing ? and do n't forget his support of the coup in chile that replaced the democratically-elected president allende with a brutal military dictator . '' `` it was part of the fight against communism . '' `` were n't tyranny and violence the reasons we opposed communism to begin with ? or was it just fear of the lower class rising up against the rich ? '' `` president nixon could n't have predicted the violence of pinochet 's regime , and being anti-communist did n't mean neglecting the poor . he proposed a guaranteed basic income for all american families , still a radical concept today . and he even pushed for comprehensive healthcare reform , just the kind that passed 40 years later . '' `` i 'm still confused about this burglary business . was he a crook or not ? '' `` your honor , president nixon may have violated a law or two , but what was the real harm compared to all he accomplished while in office ? '' `` the harm was to democracy itself . the whole point of the ideals nixon claimed to promote abroad is that leaders are accountable to the people , and when they hold themselves above the law for whatever reason , those ideals are undermined . '' `` and if you do n't hold people accountable to the law , i 'll be out of a job . '' many politicians have compromised some principles to achieve results , but law-breaking and cover-ups threaten the very fabric the nation is built on . those who do so may find their entire legacy tainted when history is put on trial .
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hardly . nixon 's presidential campaign courted southern voters through fear and resentment of the civil rights movement . '' `` speaking of civil rights , the prosecution may be surprised to learn that he signed the title ix amendment , banning gender-based discrimination in education , and ensured that desegregation of schools occurred peacefully , and he lowered the voting age to 18 , so that students could vote . ''
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why was it improper for nixon 's campaign aides to travel to vietnam before the election ?
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around 1159 a.d. , a mathematician called bhaskara the learned sketched a design for a wheel containing curved reservoirs of mercury . he reasoned that as the wheels spun , the mercury would flow to the bottom of each reservoir , leaving one side of the wheel perpetually heavier than the other . the imbalance would keep the wheel turning forever . bhaskara 's drawing was one of the earliest designs for a perpetual motion machine , a device that can do work indefinitely without any external energy source . imagine a windmill that produced the breeze it needed to keep rotating . or a lightbulb whose glow provided its own electricity . these devices have captured many inventors ' imaginations because they could transform our relationship with energy . for example , if you could build a perpetual motion machine that included humans as part of its perfectly efficient system , it could sustain life indefinitely . there 's just one problem . they do n't work . ideas for perpetual motion machines all violate one or more fundamental laws of thermodynamics , the branch of physics that describes the relationship between different forms of energy . the first law of thermodynamics says that energy ca n't be created or destroyed . you ca n't get out more energy than you put in . that rules out a useful perpetual motion machine right away because a machine could only ever produce as much energy as it consumed . there would n't be any left over to power a car or charge a phone . but what if you just wanted the machine to keep itself moving ? inventors have proposed plenty of ideas . several of these have been variations on bhaskara 's over-balanced wheel with rolling balls or weights on swinging arms . none of them work . the moving parts that make one side of the wheel heavier also shift its center of mass downward below the axle . with a low center of mass , the wheel just swings back and forth like a pendulum , then stops . what about a different approach ? in the 17th century , robert boyle came up with an idea for a self-watering pot . he theorized that capillary action , the attraction between liquids and surfaces that pulls water through thin tubes , might keep the water cycling around the bowl . but if the capillary action is strong enough to overcome gravity and draw the water up , it would also prevent it from falling back into the bowl . then there are versions with magnets , like this set of ramps . the ball is supposed to be pulled upwards by the magnet at the top , fall back down through the hole , and repeat the cycle . this one fails because like the self-watering pot , the magnet would simply hold the ball at the top . even if it somehow did keep moving , the magnet 's strength would degrade over time and eventually stop working . for each of these machines to keep moving , they 'd have to create some extra energy to nudge the system past its stopping point , breaking the first law of thermodynamics . there are ones that seem to keep going , but in reality , they invariably turn out to be drawing energy from some external source . even if engineers could somehow design a machine that did n't violate the first law of thermodynamics , it still would n't work in the real world because of the second law . the second law of thermodynamics tells us that energy tends to spread out through processes like friction . any real machine would have moving parts or interactions with air or liquid molecules that would generate tiny amounts of friction and heat , even in a vacuum . that heat is energy escaping , and it would keep leeching out , reducing the energy available to move the system itself until the machine inevitably stopped . so far , these two laws of thermodynamics have stymied every idea for perpetual motion and the dreams of perfectly efficient energy generation they imply . yet it 's hard to conclusively say we 'll never discover a perpetual motion machine because there 's still so much we do n't understand about the universe . perhaps we 'll find new exotic forms of matter that 'll force us to revisit the laws of thermodynamics . or maybe there 's perpetual motion on tiny quantum scales . what we can be reasonably sure about is that we 'll never stop looking . for now , the one thing that seems truly perpetual is our search .
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there are ones that seem to keep going , but in reality , they invariably turn out to be drawing energy from some external source . even if engineers could somehow design a machine that did n't violate the first law of thermodynamics , it still would n't work in the real world because of the second law . the second law of thermodynamics tells us that energy tends to spread out through processes like friction . any real machine would have moving parts or interactions with air or liquid molecules that would generate tiny amounts of friction and heat , even in a vacuum .
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why does the second law of thermodynamics make perpetual motion machines impossible ( to date ) ?
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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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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 ? ''
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think of a contemporary political figure in the world today . how are his/her actions viewed as both “ heroic ” and “ villainous ” at the same time ? how do you think he/she will be viewed in 10 years ? how about in 100 years ?
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translator : andrea mcdonough reviewer : bedirhan cinar this is zeno of elea , an ancient greek philosopher famous for inventing a number of paradoxes , arguments that seem logical , but whose conclusion is absurd or contradictory . for more than 2,000 years , zeno 's mind-bending riddles have inspired mathematicians and philosophers to better understand the nature of infinity . one of the best known of zeno 's problems is called the dichotomy paradox , which means , `` the paradox of cutting in two '' in ancient greek . it goes something like this : after a long day of sitting around , thinking , zeno decides to walk from his house to the park . the fresh air clears his mind and help him think better . in order to get to the park , he first has to get half way to the park . this portion of his journey takes some finite amount of time . once he gets to the halfway point , he needs to walk half the remaining distance . again , this takes a finite amount of time . once he gets there , he still needs to walk half the distance that 's left , which takes another finite amount of time . this happens again and again and again . you can see that we can keep going like this forever , dividing whatever distance is left into smaller and smaller pieces , each of which takes some finite time to traverse . so , how long does it take zeno to get to the park ? well , to find out , you need to add the times of each of the pieces of the journey . the problem is , there are infinitely many of these finite-sized pieces . so , should n't the total time be infinity ? this argument , by the way , is completely general . it says that traveling from any location to any other location should take an infinite amount of time . in other words , it says that all motion is impossible . this conclusion is clearly absurd , but where is the flaw in the logic ? to resolve the paradox , it helps to turn the story into a math problem . let 's supposed that zeno 's house is one mile from the park and that zeno walks at one mile per hour . common sense tells us that the time for the journey should be one hour . but , let 's look at things from zeno 's point of view and divide up the journey into pieces . the first half of the journey takes half an hour , the next part takes quarter of an hour , the third part takes an eighth of an hour , and so on . summing up all these times , we get a series that looks like this . `` now '' , zeno might say , `` since there are infinitely many of terms on the right side of the equation , and each individual term is finite , the sum should equal infinity , right ? '' this is the problem with zeno 's argument . as mathematicians have since realized , it is possible to add up infinitely many finite-sized terms and still get a finite answer . `` how ? '' you ask . well , let 's think of it this way . let 's start with a square that has area of one meter . now let 's chop the square in half , and then chop the remaining half in half , and so on . while we 're doing this , let 's keep track of the areas of the pieces . the first slice makes two parts , each with an area of one-half the next slice divides one of those halves in half , and so on . but , no matter how many times we slice up the boxes , the total area is still the sum of the areas of all the pieces . now you can see why we choose this particular way of cutting up the square . we 've obtained the same infinite series as we had for the time of zeno 's journey . as we construct more and more blue pieces , to use the math jargon , as we take the limit as n tends to infinity , the entire square becomes covered with blue . but the area of the square is just one unit , and so the infinite sum must equal one . going back to zeno 's journey , we can now see how how the paradox is resolved . not only does the infinite series sum to a finite answer , but that finite answer is the same one that common sense tells us is true . zeno 's journey takes one hour .
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you ask . well , let 's think of it this way . let 's start with a square that has area of one meter .
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let ’ s go back to the dichotomy . apart from the problem that summing an infinite series can give a finite result , there are other problems with the reasoning that led to the paradox . can you think of any ?
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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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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 .
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the pituitary gland _____
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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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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 .
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using the system outlined in the video , determine your animal and your element .
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say two people are walking down the street , and they bump into each other . they 'll just shake it off and walk on . sometimes that happens with molecules too . they just bounce off each other , and that 's that . but what if two people were to bump into each other , and during that collision , one person 's arm got severed and reattached to the other person 's face ? now that sounds really weird , but it 's similar to one of the many ways that molecules can react with each other . two molecules can join and become one . one can split apart and become two . molecules can switch parts . all these changes are chemical reactions , and we can see them happening around us . for example , when fireworks explode , or iron rusts , or milk goes bad , or people are born , grow old , die , and then decompose . but chemical reactions do n't just happen willy nilly ! everything has to be right . first , the molecules have to hit each other in the right orientation . and second , they have to hit each other hard enough , in other words , with enough energy . now you 're probably thinking that a reaction just happens in one direction and that 's it . sometimes that 's true . for example , things ca n't unburn or unexplode . but most reactions can happen in both directions , forward and reverse . there 's no reason that our face-arm guy ca n't bump into armless girl , reattaching that arm back to its original socket . now let 's zoom out a bit . now let 's say that you 've got a thousand people on the street , and all of them start with their limbs normally attached . at the beginning , every collision is a chance for person a to transfer an arm to person b 's face . and so at the beginning , more and more people end up with arms attached to their faces or arms missing . but as the number of people with arm-faces and missing arms grows , collisions between those people become more likely . and when they bump into each other , guess what ? normal-appendage people are reproduced . now the number of limb transfers per second forward will start high and then fall , and the number of limb transfers per second backward will start at zero and then rise . eventually they 'll meet , they 'll be the same . and when that happens , the number of people in each state stops changing , even though people are still bumping into each other and exchanging limbs . now how many people do you think there are in each state ? half and half , right ? no , well , maybe . it depends . it could be 50/50 , but it could be 60/40 or 15/85 , or anything . we chemists have to get our little , gloved hands dirty - ah , well , we 're in a lab so not really dirty - to figure out what the actual distribution of molecules is . even though each of limb transfers is a pretty dramatic event for the people involved , if we zoom out , we see population numbers that do n't change . we call this nirvana equilibrium , and it does n't just happen with chemical reactions . things like gene pools and highway traffic show the same pattern . it looks pretty still from 30,000 feet , but there is lots of crazy stuff happening on the ground , you just need to zoom in to see it .
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and second , they have to hit each other hard enough , in other words , with enough energy . now you 're probably thinking that a reaction just happens in one direction and that 's it . sometimes that 's true .
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what is/are the requirement ( s ) for a collision to result in a reaction ?
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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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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 .
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if somebody wanted to translate the phrase “ you did it ! ” into spanish , and they knew that the speaker used “ you ” to refer to more than one person , what additional information would they not first need to find out ?
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so we 're gon na go find some liquid nitrogen . we keep it in a really large dewar tank at the back of the shop , so we 're gon na go find that now . so this is a dewar that we used to keep the liquid nitrogen in within the building so it 's much more convenient for us and our students to get it . so what we 're gon na do now is we 're gon na fill up our small dewar to carry the nitrogen back to the lab . so you can probably hear it hissing and fizzing going into the bottle , and you can see all the nitrogen evaporating off . nitrogen exists as a gas . molecules of n2 . and it is interesting , because the bond between the two nitrogen atoms is the strongest bond that you can get between any two atoms in the periodic table . any two atoms that are the same . sometimes , if you have two atoms that are different , the bond can be slightly stronger , but the nn triple bond is one of the strongest that you can have . so what we 're doing is we 're filling up the dewar with liquid nitrogen so that we can take that back to our lab to do our next experiment . so many explosive compounds , things that you 've heard of , like tnt and other explosives , all contain nitrogen , which are isolated atoms , and when the explosion goes off the atoms come together and release energy . nitrogen is used widely in laboratories , partly because it 's not as reactive as oxygen , so if you do an experiment in an atmosphere of nitrogen you can avoid reactions that might occur with air . you can also use nitrogen when it 's liquified as a coolant . liquid nitrogen boils at -196 degrees centigrade , 77 degrees absolute , and you can just hold it in a normal thermous flask . so this is a dewar of liquid nitrogen , and you can see that the nitrogen is evaporating from the top , coming out and frosting , coming down over the sides because it 's a little bit more dense than the air . you can see it 's heavily laden with ice , and you can see that the ice crystals are starting to grow on the top of the dewar here . it 's very cold though , so we must n't touch it for too long . so if we just tip some out on the floor , we can see that the nitrogen itself will come out like a liquid , like pouring water , but the interesting thing is , water , when i pour it on the floor it forms a puddle . it does nothing useful . in fact , it sort of gets in the way . but liquid nitrogen , when i pour it on the floor , it forms these really quite nice bubbles , and they fly across to the side of the room and take all the dust with them . pretty cool . but if you put materials like rubber or flowers into liquid nitrogen , instead of being soft and bendy they become really rigid , and you can smash them with a hammer . so you can see all of the bubbles forming on this steel tray now , and they 're sweeping away all the dust quite nicely as they evaporate and move further afield . so neil 's got a piece of tubing , and it 's really quite flexible tubing , you can see it 's really floppy , and now he 's gon na put it into the cryogenic liquid nitrogen and freeze it , and see what happens to the rubber . but you see another interesting thing there is that the liquid nitrogen is siphoning out through the tube , and that 's a really good joke , because you can direct that siphon at someones trousers and freeze their legs . so i think that 's enough , neil , let 's see if it 's a bit harder . wow , that shattered . and there 's quite a nice little operation that i 've heard about , in which you can take the lens out of somebody 's eye when they 're suitably anaesthetized , and this lens can be frozen and then put on the lathe and you can change its shape so you get the right shape , and then you let it unfreeze , it goes soft again , and you pop it back into their eye . . . . . . . . . . . . . captions by www.subply.com
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so you can probably hear it hissing and fizzing going into the bottle , and you can see all the nitrogen evaporating off . nitrogen exists as a gas . molecules of n2 .
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on a packet of crisps ( chips in the usa ) , you will often see something similar to “ atmosphere of nitrogen ” written on the packet . why is the pack full of nitrogen instead of air ?
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scientific breakthrough , the kind that can potentially save lives , can sometimes be lying right out in the open for us to discover , in the evolved , accumulated body of human anecdote , for example , or in the time-tested adaptations that we observe in the natural world around us . science starts with observation , but the trick is to identify the patterns and signatures that we might otherwise dismiss as myth or coincidence , isolate them , and test them with scientific rigor . and when we do , the results will often surprise . western australia has had a particular problem with shark attacks over the last three years , unfortunately and tragically culminating in five fatal shark attacks in a 10-month period during that time . but western australia is not alone in this . the incident of shark engagements on humans is escalating worldwide . and so it 's not surprising , perhaps , that in july of this year , shark attack mitigation systems in collaboration with the university of western australia oceans institute made an announcement which captured the attention of the worldwide media and of ocean users worldwide , and that was around the development of technology to mitigate or reduce the risk of shark attack based on the science of what sharks can see . and i have for you today the story of that journey , but also the notion that science can be as powerful as a translator as it can be for invention . when we began this process , we were looking , it was about three years ago , and we 'd just had the first two fatal shark attacks in western australia , and by chance , in a previous role , i happened to be having dinner with harry butler . now harry butler , who most australians would know is a famous naturalist , had spent a lot of time in the marine environment . harry butler is a precursor , if you like , to the late steve irwin . when i asked him about what the solution to the problem might be , the answer was quite surprising . he said , `` take a black wetsuit , band it in yellow stripes like a bumblebee , and you 'll be mimicking the warning systems of most marine species . '' i did n't think about that much at the time , and it was n't until the next three fatal shark attacks happened , and it caused me to think , maybe there 's some merit to this idea . and i turned to the web to see if there might be some clues . and it turns out the web is awash with this sort of evidence that supports this sort of thinking . so biologically , there are plenty of species that display banding or patterns , warning patterns , to either be cryptical in the water or warn against being attacked , not the least of which is the pilot fish which spends a big slab of its life around the business end of a shark . on the human side , walter starck , an oceanographer , has been painting his wetsuit since the 1970s , and anthropologically , pacific island tribes painted themselves in bands in a sea snake ceremony to ward off the shark god . so what 's going on here ? is this an idea lying wide out in the open for us to consider and define ? we know that sharks use a range of sensors when they engage , particularly for attack , but the sight sensor is the one that they use to identify the target , and particularly in the last number of meters before the attack . it makes sense to pay attention to the biological anecdote because that 's time-tested evolution over many millennia . but is n't human anecdote also an evolution of sorts , the idea that there 's a kernel of truth thought to be important , passed down from generation to generation , so that it actually ends up shaping human behavior ? i wanted to test this idea . i wanted to put some science to this anecdotal evidence , because if science could support this concept , then we might have at least part of the solution to shark attack right under our very nose . to do that , i needed some experts in shark vision and shark neurology , and a worldwide search , again , led to the university of w.a . on the doorstep here , with the oceans institute . and professor nathan hart and his team had just written a paper which tells us , confirms that predatory sharks see in black and white , or grayscale . so i called up nathan , a little bit sheepishly , actually , about this idea that maybe we could use these patterns and shapes to produce a wetsuit to try and mitigate the risk of shark attack , and fortunately , he thought that was a good idea . so what ensued is a collaborative bit of research supported by the west australian state government . and we did three key things . the first is that we mapped the characteristics , the physical characteristics of the eyes of the three main predatory sharks , so the great white , tiger and bull shark . we did that genetically and we did that anatomically . the next thing we did was to understand , using complex computer modeling , what that eye can see at different depths , distances , light conditions , and water clarity in the ocean . and from there , we were able to pinpoint two key characteristics : what patterns and shapes would present the wearer as hidden or hard to make out in the water , cryptic , and what patterns and shapes might provide the greatest contrast but provide the greatest breakup of profile so that that person was n't confused for shark prey or shark food . the next thing we needed to do was to convert this into wetsuits that people might actually wear , and to that end , i invited ray smith , a surfer , industrial designer , wetsuit designer , and in fact the guy that designed the original quiksilver logo , to come over and sit with the science team and interpret that science into aesthetic wetsuits that people might actually wear . and here 's an example of one of the first drawings . so this is what i call a `` do n't eat me '' wetsuit . so this takes that banding idea , takes that banding idea , it 's highly visible , provides a highly disruptive profile , and is intended to prevent the shark from considering that you would be ordinary food , and potentially even create confusion for the shark . and this one 's configured to go with a surfboard . you can see that dark , opaque panel on the front , and it 's particularly better for the surface , where being backlit and providing a silhouette is problematic . second iteration is the cryptic wetsuit , or the one which attempts to hide the wearer in the water column . there are three panels on this suit , and in any given conditions , one or more of those panels will match the reflective spectra of the water so as to disappear fully or partially , leaving the last panel or panels to create a disruptive profile in the water column . and this one 's particularly well-suited to the dive configuration , so when you 're deeper under the water . so we knew that we had some really solid science here . we knew , if you wanted to stand out , you needed to look stripy , and we knew if you wanted to be cryptic , you needed to look like this . but the acid test is always going to be , how would sharks really behave in the context of these patterns and shapes . and testing to simulate a person in a wetsuit in the water with a predatory shark in a natural environment is actually a lot harder than you might think . ( laughter ) so we have to bait the rig , because we need to get the statistical number of samples through to get the scientific evidence , and by baiting the rig , we 're obviously changing shark behavior . we ca n't put humans in the water . we 're ethically precluded from even using humanoid shapes and baiting them up in the water . but nevertheless , we started the testing process in january of this year , initially with tiger sharks and subsequently with great white sharks . the way we did that was to get a perforated drum which is full of bait , wrap it in a neoprene skin , and then run two stereo underwater cameras to watch how the shark actually engages with that rig . and because we use stereo , we can capture all the statistics on how big the shark is , what angle it comes in at , how quickly it leaves , and what its behavior is in an empirical rather than a subjective way . because we needed to preserve the scientific method , we ran a control rig which was a black neoprene rig just like a normal black wetsuit against the , what we call , sams technology rig . and the results were not just exciting , but very encouraging , and today i would like to just give you a snapshot of two of those engagements . so here we 've got a four-meter tiger shark engaging the black control rig , which it had encountered about a minute and a half before . now that exact same shark had engaged , or encountered this sams rig , which is the elude sams rig , about eight minutes before , and spent six minutes circling it , hunting for it , looking for what it could smell and sense but not see , and this was the final engagement . great white sharks are more confident than the tigers , and here you see great white shark engaging a control rig , so a black neoprene wetsuit , and going straight to the bottom , coming up and engaging . in contrast to the sams technology rig , this is the banded one , where it 's more tactile , it 's more investigative , it 's more apprehensive , and shows a reluctance to come straight in and go . ( applause ) so , it 's important for us that all the testing is done independently , and the university of w.a . is doing the testing . it 'll be an ongoing process . it 's subject to peer review and subject to publication . it 's so important that this concept is led with the science . from the perspective of shark attack mitigation systems , we 're a biotechnology licensing company , so we do n't make wetsuits ourselves . we 'll license others to do that . but i thought you might be interested in seeing what sams technology looks like embedded in a wetsuit , and to that end , for the first time , live , worldwide -- ( laughter ) — i can show you what biological adaptation , science and design looks like in real life . so i can welcome sam , the surfer , from this side . where are you , sam ? ( applause ) and eduardo . ( applause ) cheers , mate . cheers . thanks , gentlemen . ( applause ) so what have we done here ? well , to my mind , rather than take a blank sheet and use science as a tool for invention , we 've paid attention to the biological evidence , we 've put importance to the human anecdotal evidence , and we 've used science as a tool for translation , translation of something that was already there into something that we can use for the benefit of mankind . and it strikes me that this idea of science as a tool for translation rather than invention is one that we can apply much more widely than this in the pursuit of innovation . after all , did the wright brothers discover manned flight , or did they observe the biological fact of flight and translate that mechanically , replicate it in a way that humans could use ? as for the humble wetsuit , who knows what oceanwear will look like in two years ' time , in five years ' time or in 50 years ' time , but with this new thinking , i 'm guessing there 's a fair chance it wo n't be pure black . thank you . ( applause )
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and here 's an example of one of the first drawings . so this is what i call a `` do n't eat me '' wetsuit . so this takes that banding idea , takes that banding idea , it 's highly visible , provides a highly disruptive profile , and is intended to prevent the shark from considering that you would be ordinary food , and potentially even create confusion for the shark .
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what 2 things did the team do to create a wetsuit that would n't confuse a person with prey ?
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you have about 20,000 genes in your dna . they encode the molecules that make up your body , from the keratin in your toenails , to the collagen at the tip of your nose , to the dopamine surging around inside your brain . other species have genes of their own . a spider has genes for spider silk . an oak tree has genes for chlorophyll , which turns sunlight into wood . so where did all those genes come from ? it depends on the gene . scientists suspect that life started on earth about 4 billion years ago . the early life forms were primitive microbes with a basic set of genes for the basic tasks required to stay alive . they passed down those basic genes to their offspring through billions of generations . some of them still do the same jobs in our cells today , like copying dna . but none of those microbes had genes for spider silk or dopamine . there are a lot more genes on earth today than there were back then . it turns out that a lot of those extra genes were born from mistakes . each time a cell divides , it makes new copies of its dna . sometimes it accidentally copies the same stretch of dna twice . in the process , it may make an extra copy of one of its genes . at first , the extra gene works the same as the original one . but over the generations , it may pick up new mutations . those mutations may change how the new gene works , and that new gene may duplicate again . a surprising number of our mutated genes emerged more recently ; many in just the past few million years . the youngest evolved after our own species broke off from our cousins , the apes . while it may take over a million years for a single gene to give rise to a whole family of genes , scientists are finding that once the new genes evolve , they can quickly take on essential functions . for example , we have hundreds of genes for the proteins in our noses that grab odor molecules . the mutations let them grab different molecules , giving us the power to perceive trillions of different smells . sometimes mutations have a bigger effect on new copies of genes . they may cause a gene to make its protein in a different organ , or at a different time of life , or the protein may start doing a different job altogether . in snakes , for example , there 's a gene that makes a protein for killing bacteria . long ago , the gene duplicated and the new copy mutated . that mutation changed the signal in the gene about where it should make its protein . instead of becoming active in the snake 's pacreas , it started making this bacteria-killing protein in the snake 's mouth . so when the snake bit its prey , this enzyme got into the animal 's wound . and when this protein proved to have a harmful effect , and helped the snake catch more prey , it became favored . so now what was a gene in the pancreas makes a venom in the mouth that kills the snake 's prey . and there are even more incredible ways to make a new gene . the dna of animals and plants and other species contain huge stretches without any protein coding genes . as far as scientists can tell , its mostly random sequences of genetic gibberish that serve no function . these stretches of dna sometimes mutate , just like genes do . sometimes those mutations turn the dna into a place where a cell can start reading it . suddenly the cell is making a new protein . at first , the protein may be useless , or even harmful , but more mutations can change the shape of the protein . the protein may start doing something useful , something that makes an organism healthier , stronger , better able to reproduce . scientists have found these new genes at work in many parts of animal bodies . so our 20,000 genes have many origins , from the origin of life , to new genes still coming into existence from scratch . as long as life is here on earth , it will be making new genes .
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but none of those microbes had genes for spider silk or dopamine . there are a lot more genes on earth today than there were back then . it turns out that a lot of those extra genes were born from mistakes .
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explain how mutations have created more/different genes on earth today than in the past . be sure to include all of the necessary steps !
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your research team has found a prehistoric virus preserved in the permafrost and isolated it for study . after a late night working , you 're just closing up the lab when a sudden earthquake hits and knocks out the power . as the emergency generators kick in , an alarm confirms your worst fears : all the sample vials have broken . the virus is contained for now , but unless you can destroy it , the vents will soon open and unleash a deadly airborne plague . without hesitation , you grab your hazmat suit and get ready to save the world . the lab is a four by four compound of 16 rooms with an entrance on the northwest corner and an exit at the southeast . each room is connected to the adjacent ones by an airlock , and the virus has been released in every room except the entrance . to destroy it , you must enter each contaminated room and pull its emergency self-destruct switch . but there 's a catch . because the security system is on lockdown , once you enter the contaminated room , you ca n't exit without activating the switch , and once you 've done so , you wo n't be able to go back in to that room . you start to draw out possible routes on a pad of paper , but nothing seems to get you to the exit without missing at least one room . so how can you destroy the virus in every contaminated room and survive to tell the story ? pause here if you want to figure it out for yourself . answer in : 3 answer in : 2 answer in : 1 if your first instinct is to try to graph your possible moves on a grid , you 've got the right idea . this puzzle is related to the hamiltonian path problem named after the 19th century irish mathematician william rowan hamilton . the challenge of the path problem is to find whether a given graph has a hamiltonian path . that 's a route that visits every point within it exactly once . this type of problem , classified as np-complete , is notoriously difficult when the graph is sufficiently large . although any proposed solution can be easily verified , we have no reliable formula or shortcut for finding one , or determining that one exists . and we 're not even sure if it 's possible for computers to reliably find such solutions , either . this puzzle adds a twist to the hamiltonian path problem in that you have to start and end at specific points . but before you waste a ton of graph paper , you should know that a true hamiltonian path is n't possible with these end points . that 's because the rooms form a grid with an even number of rooms on each side . in any grid with that configuration , a hamiltonian path that starts and ends in opposite corners is impossible . here 's one way of understanding why . consider a checkerboard grid with an even number of squares on each side . every path through it will alternate black and white . these grids will all also have an even total number of squares because an even number times and even number is even . so a hamiltonian path on an even-sided grid that starts on black will have to end on white . and one that starts on white will have to end on black . however , in any grid with even numbered sides , opposite corners are the same color , so it 's impossible to start and end a hamiltonian path on opposite corners . it seems like you 're out of luck , unless you look at the rules carefully and notice an important exception . it 's true that once you activate the switch in a contaminated room , it 's destroyed and you can never go back . but there 's one room that was n't contaminated - the entrance . this means that you can leave it once without pulling the switch and return there when you 've destroyed either of these two rooms . the corner room may have been contaminated from the airlock opening , but that 's okay because you can destroy the entrance after your second visit . that return trip gives you four options for a successful route , and a similar set of options if you destroyed this room first . congratulations . you 've prevented an epidemic of apocalyptic proportions , but after such a stressful episode , you need a break . maybe you should take up that recent job offer to become a traveling salesman .
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but there 's a catch . because the security system is on lockdown , once you enter the contaminated room , you ca n't exit without activating the switch , and once you 've done so , you wo n't be able to go back in to that room . you start to draw out possible routes on a pad of paper , but nothing seems to get you to the exit without missing at least one room .
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suppose the size of the room was not n x n , but n x m. what do you know about the values of n and m that would make it possible to go directly from the northwest corner to the southeast corner without having to re-enter a room ? what values would make it impossible ?
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when ultraviolet sunlight hits our skin , it affects each of us a little differently . depending on skin color , it will take only minutes of exposure to turn one person beetroot-pink , while another requires hours to experience the slightest change . so what 's to account for that difference and how did our skin come to take on so many different hues to begin with ? whatever the color , our skin tells an epic tale of human intrepidness and adaptability , revealing its variance to be a function of biology . it all centers around melanin , the pigment that gives skin and hair its color . this ingredient comes from skin cells called melanocytes and takes two basic forms . there 's eumelanin , which gives rise to a range of brown skin tones , as well as black , brown , and blond hair , and pheomelanin , which causes the reddish browns of freckles and red hair . but humans were n't always like this . our varying skin tones were formed by an evolutionary process driven by the sun . in began some 50,000 years ago when our ancestors migrated north from africa and into europe and asia . these ancient humans lived between the equator and the tropic of capricorn , a region saturated by the sun 's uv-carrying rays . when skin is exposed to uv for long periods of time , the uv light damages the dna within our cells , and skin starts to burn . if that damage is severe enough , the cells mutations can lead to melanoma , a deadly cancer that forms in the skin 's melanocytes . sunscreen as we know it today did n't exist 50,000 years ago . so how did our ancestors cope with this onslaught of uv ? the key to survival lay in their own personal sunscreen manufactured beneath the skin : melanin . the type and amount of melanin in your skin determines whether you 'll be more or less protected from the sun . this comes down to the skin 's response as sunlight strikes it . when it 's exposed to uv light , that triggers special light-sensitive receptors called rhodopsin , which stimulate the production of melanin to shield cells from damage . for light-skin people , that extra melanin darkens their skin and produces a tan . over the course of generations , humans living at the sun-saturated latitudes in africa adapted to have a higher melanin production threshold and more eumelanin , giving skin a darker tone . this built-in sun shield helped protect them from melanoma , likely making them evolutionarily fitter and capable of passing this useful trait on to new generations . but soon , some of our sun-adapted ancestors migrated northward out of the tropical zone , spreading far and wide across the earth . the further north they traveled , the less direct sunshine they saw . this was a problem because although uv light can damage skin , it also has an important parallel benefit . uv helps our bodies produce vitamin d , an ingredient that strengthens bones and lets us absorb vital minerals , like calcium , iron , magnesium , phosphate , and zinc . without it , humans experience serious fatigue and weakened bones that can cause a condition known as rickets . for humans whose dark skin effectively blocked whatever sunlight there was , vitamin d deficiency would have posed a serious threat in the north . but some of them happened to produce less melanin . they were exposed to small enough amounts of light that melanoma was less likely , and their lighter skin better absorbed the uv light . so they benefited from vitamin d , developed strong bones , and survived well enough to produce healthy offspring . over many generations of selection , skin color in those regions gradually lightened . as a result of our ancestor 's adaptability , today the planet is full of people with a vast palette of skin colors , typically , darker eumelanin-rich skin in the hot , sunny band around the equator , and increasingly lighter pheomelanin-rich skin shades fanning outwards as the sunshine dwindles . therefore , skin color is little more than an adaptive trait for living on a rock that orbits the sun . it may absorb light , but it certainly does not reflect character .
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for light-skin people , that extra melanin darkens their skin and produces a tan . over the course of generations , humans living at the sun-saturated latitudes in africa adapted to have a higher melanin production threshold and more eumelanin , giving skin a darker tone . this built-in sun shield helped protect them from melanoma , likely making them evolutionarily fitter and capable of passing this useful trait on to new generations .
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if early humans were able to adapt to living in less sun-saturated climates after leaving africa , explain how modern humans with less eumelanin could adapt to living in sun-saturated climates after leaving europe and asia today ?
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translator : tom carter reviewer : bedirhan cinar take an adjective such as `` implacable , '' or a verb like `` proliferate , '' or even another noun , `` crony , '' and add a suffix , such as `` -ity , '' or `` -tion , '' or `` -ism . '' you 've created a new noun . `` implacability , '' `` proliferation , '' `` cronyism . '' sounds impressive , right ? wrong ! you 've just unleashed a flesh-eating zombie . nouns made from other parts of speech are called nominalizations . academics love them . so do lawyers , bureaucrats , business writers . i call them zombie nouns , because they consume the living . they cannibalize active verbs , they suck the lifeblood from adjectives , and they substitute abstract entities for human beings . here 's an example . `` the proliferation of nominalizations in a discursive formation may be an indication of a tendency towards pomposity and abstraction . '' huh ? this sentence contains no fewer than seven nominalizations , yet it fails to tell us who is doing what . when we eliminate , or reanimate , most of the zombie nouns , so `` tendency '' becomes `` tend , '' `` abstraction '' becomes `` abstract , '' then we add a human subject and some active verbs , the sentence springs back to life . `` writers who overload their sentences with nominalizations tend to sound pompous and abstract . '' only one zombie noun -- the key word `` nominalizations '' -- has been allowed to remain standing . at their best , nominalizations help us express complex ideas , perception , intelligence , epistemology . at their worst , they impede clear communication . to get a feeling for how zombie nouns work , release a few of them into a lively sentence and watch them sap all its energy . george orwell played this game in his essay `` politics in the english language . '' he started with a well-known verse from the book of ecclesiastes in the bible . it says `` i returned and saw under the sun , that the race is not to the swift , nor the battle to the strong , neither yet bread to the wise , nor yet riches to men of understanding , nor yet favor to men of skill ; but time and chance happeneth to them all . '' now here 's orwell 's modern english version . `` objective considerations of contemporary phenomena compel the conclusion that success or failure in competitive activities exhibits no tendency to be commensurate with innate capacity , but that a considerable element of the unpredictable must invariably be taken into account . '' the bible passage speaks to our senses and emotions with concrete nouns , descriptions of people , and punchy , abstract nouns such as `` race , '' `` battle , '' `` riches , '' `` time , '' `` chance . '' not a zombie among them . orwell 's satirical translation , on the other hand , is teeming with nominalizations and other vague abstractions . the zombies have taken over , and the humans have fled the village . zombie nouns do their worst damage when they gather in jargon-generating packs and swallow every noun , verb and adjective in sight . so `` globe '' becomes `` global , '' becomes `` globalize , '' becomes `` globalization . '' the grandfather of all nominalizations , antidisestablishmentarianism , contains at least two verbs , three adjectives , and six other nouns inside its distended belly . a paragraph heavily populated by nominalizations will send your readers straight to sleep . rescue them from the zombie apocalypse with vigorous verb-driven sentences that are concrete and clearly structured . you want your sentences to live , not to join the living dead .
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`` objective considerations of contemporary phenomena compel the conclusion that success or failure in competitive activities exhibits no tendency to be commensurate with innate capacity , but that a considerable element of the unpredictable must invariably be taken into account . '' the bible passage speaks to our senses and emotions with concrete nouns , descriptions of people , and punchy , abstract nouns such as `` race , '' `` battle , '' `` riches , '' `` time , '' `` chance . '' not a zombie among them .
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the ecclesiastes passage is filled with concrete language , but it also contains abstract nouns such as race , battle , riches , time , and chance . how do these abstract nouns differ from nominalizations in their effect on the reader ?
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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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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 .
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which is one thing that mohr suggests considering to help begin your introduction ?
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translator : andrea mcdonough reviewer : bedirhan cinar normally astronaut training takes about one full year , and it includes such subjects as astronomy , astrophysics , flight physiology , orbital trajectories , or orbital management . another part of the astronaut basic training is survival training . in the days of gemini , you never knew for sure where a spacecraft might land if there was an emergency , deorbit . so , we had to take desert training , water training , and jungle survival training . so , we had to learn how to cook and eat snake and all other , such other good things as that , and how to make water in a desert . after that year and a half of astronaut basic training , our names were all put on a list and that list was quite a bit longer at that time then there were seats available . and so , we were all given other duties to keep us occupied and to help continue our training . five of us were assigned to the lunar module , and our job was to be with these lunar modules as they were being built . so , we spent a lot of time there . i must admit that probably i had more time sleeping on the floor of lunar module # 6 than the crew who flew it on the moon . well , my next job was to be on the support crew of apollo 8 , and apollo 8 was the spacecraft that flew to the moon and came back but did not land . when they went behind the moon , they were supposed to do a thrusting maneuver to slow them down so they would be captured into lunar orbit . so we just had to sit and cool our heels when they went behind the moon , and we knew if they came out a little early on the other side , that they had not burned enough , not slowed down enough , and were going to skip out into space , they would n't be captured in orbit . if they came out a little bit late , it meant they had over-done it , and they were n't going to be in orbit , but were going to begin a spiral down to the lunar surface . and , of course , without a lunar module , that kind of ruins your whole day . you can imagine how relieved we were at the instant that they were supposed to appear on the other side of the moon that they appeared ! my next assignment was again a support crew assignment on apollo 12 , and apollo 12 was struck by lightning on its way off the pad . a nearby thunderstorm , there was a lightning bolt that went over and hit the very tip of the spacecraft . the charge went down through the spacecraft , through the booster , down the exhaust gases , and grounded out on the launching pad . it killed the electrical power system and the computers all died . you can imagine what it must have been like for them inside because suddenly the lights all went out and then they came back on when the batteries picked up the load . and , every single warning light and caution light in the spacecraft was on and flashing , and all the necessary bells , whistles , and buzzards and things that are in there , all were going off at the same time . the crew was totally confused as to what was going on . when we were settled in orbit , we tested all the various systems and everything looked good . so , that , now i figured this is it , and sure enough , i did get an assignment , a flight assignment . i was assigned to the back-up crew of apollo 16 , which meant that i was to be on the param crew of apollo 19 . and , several weeks into the training , nasa made the surprise announcment that they were going to cancel apollos 18 , 19 , and 20 . we were in the middle of the vietnam war , the budget was in bad shape , so you can imagine there were three very , very sad hangdog guys moping around the office because we lost our flight to the moon . but , several weeks later , i got a call from tom stafford , the senior astronaut at that time , and he wanted me in his office , and i went in , and he told me that he was sorry that i had missed my opportunity for the moon , but he said , `` i 've got another assignment for you . '' he said , `` i want you to be the commander of the third and final skylab mission . '' and , he said , `` do you think you could do the job ? '' and i said , `` of course , yes ! '' and , i 'll have to admit , a certain lump in my chest and in my stomach , because i was a rookie , and they normally do n't assign a rookie to be a commander , usually you have to have at least one flight under your belt , but they assigned me to that , which was really kind of a shock because the last rookie commander was neil armstrong on gemini 8 .
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translator : andrea mcdonough reviewer : bedirhan cinar normally astronaut training takes about one full year , and it includes such subjects as astronomy , astrophysics , flight physiology , orbital trajectories , or orbital management . another part of the astronaut basic training is survival training . in the days of gemini , you never knew for sure where a spacecraft might land if there was an emergency , deorbit .
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what animal does carr mentions he was taught to cook while in astronaut training ?
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have you ever seen static electricity cause a spark of light ? what is that spark ? what about lightning , the northern lights , or the tail of a comet ? all of those things , and many others , in fact 99.9 % of the universe , are made of plasma . plasma is a state of matter drastically different from the more familiar forms . take ice , for example . ice , a solid , melts to become water , a liquid , which , when heated , vaporizes into steam , a gas . continued heating of the steam at a high enough temperature causes the water molecules in it to separate into freely roaming hydrogen and oxygen atoms . with a little more heat , the ionization process occurs and the negatively charged electrons escape the atoms , leaving behind positively charged ions . this mixture of freely roaming negative and positive charges is plasma , and at a high enough temperature , any gas can be made into one . these freely moving charged particles behave very differently from the particles in other types of matter . when a doorknob , a solid , has static electricity on it , it does n't look or behave any differently . and with the exception of a compass or other magnetic object , we rarely see matter respond to a magnetic field . but put a plasma in an electric field or magnetic field , and you 'll get a very different reaction . because plasmas are charged , electric fields accelerate them , and magnetic fields steer them in circular orbits . and when the particles within plasma collide , or accelerated by electricity or magnetism , light is generated , which is what we see when we look at plasmas like the aurora borealis . plasmas are n't just beautiful , celestial phenomena , though . imagine a tiny cube made of normal gas with a very high voltage across it . the resulting electric field pushes some of the electrons off the atoms and accelerates them to high speeds causing the ionization of other atoms . imbedded impurities in the tiny cube of gas cause it to gain and release a precise amount of energy in the form of ultraviolet radiation . attached to each tiny cube , a fluorescent material glows with a specific color when ultraviolet light at just the right intensity reaches it . now , make a rectangle out of a million of these tiny cubes , each separately controlled by sophisticated electronics . you may be looking at one now . this is called a plasma tv . plasmas also have implications for health care . plasma chemists create highly specific plasmas that can destroy or alter targeted chemicals , thereby killing pathogenic organisms on food or hospital surfaces . plasmas are all around us , in forms that are both spectacular and practical . and in the future , plasma could be used to permanently rid landfills of their waste , efficiently remove toxins from our air and water , and provide us with a potentially unlimited supply of renewable clean energy .
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you may be looking at one now . this is called a plasma tv . plasmas also have implications for health care .
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where do you find plasma in your everyday life ?
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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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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 .
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bram stoker was heavily influenced by ______ , a gothic novella first published in book form in 1872 , which may have started his mind on the path of vampire fiction .
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sadness is part of the human experience , but for centuries there has been vast disagreement over what exactly it is and what , if anything , to do about it . in its simplest terms , sadness is often thought of as the natural reaction to a difficult situation . you feel sad when a friend moves away or when a pet dies . when a friend says , `` i 'm sad , '' you often respond by asking , `` what happened ? '' but your assumption that sadness has an external cause outside the self is a relatively new idea . ancient greek doctors did n't view sadness that way . they believed it was a dark fluid inside the body . according to their humoral system , the human body and soul were controlled by four fluids , known as humors , and their balance directly influenced a person 's health and temperament . melancholia comes from melaina kole , the word for black bile , the humor believed to cause sadness . by changing your diet and through medical practices , you could bring your humors into balance . even though we now know much more about the systems that govern the human body , these greek ideas about sadness resonate with current views , not on the sadness we all occasionally feel , but on clinical depression . doctors believe that certain kinds of long-term , unexplained emotional states are at least partially related to brain chemistry , the balance of various chemicals present inside the brain . like the greek system , changing the balance of these chemicals can deeply alter how we respond to even extremely difficult circumstances . there 's also a long tradition of attempting to discern the value of sadness , and in that discussion , you 'll find a strong argument that sadness is not only an inevitable part of life but an essential one . if you 've never felt melancholy , you 've missed out on part of what it means to be human . many thinkers contend that melancholy is necessary in gaining wisdom . robert burton , born in 1577 , spent his life studying the causes and experience of sadness . in his masterpiece `` the anatomy of melancholy , '' burton wrote , `` he that increaseth wisdom increaseth sorrow . '' the romantic poets of the early 19th century believed melancholy allows us to more deeply understand other profound emotions , like beauty and joy . to understand the sadness of the trees losing their leaves in the fall is to more fully understand the cycle of life that brings flowers in the spring . but wisdom and emotional intelligence seem pretty high on the hierarchy of needs . does sadness have value on a more basic , tangible , maybe even evolutionary level ? scientists think that crying and feeling withdrawn is what originally helped our ancestors secure social bonds and helped them get the support they needed . sadness , as opposed to anger or violence , was an expression of suffering that could immediately bring people closer to the suffering person , and this helped both the person and the larger community to thrive . perhaps sadness helped generate the unity we needed to survive , but many have wondered whether the suffering felt by others is anything like the suffering we experience ourselves . the poet emily dickinson wrote , `` i measure every grief i meet with narrow , probing eyes - i wonder if it weighs like mine - or has an easier size . '' and in the 20th century , medical anthropologists , like arthur kleinman , gathered evidence from the way people talk about pain to suggest that emotions are n't universal at all , and that culture , particularly the way we use language , can influence how we feel . when we talk about heartbreak , the feeling of brokenness becomes part of our experience , where as in a culture that talks about a bruised heart , there actually seems to be a different subjective experience . some contemporary thinkers are n't interested in sadness ' subjectivity versus universality , and would rather use technology to eliminate suffering in all its forms . david pearce has suggested that genetic engineering and other contemporary processes can not only alter the way humans experience emotional and physical pain , but that world ecosystems ought to be redesigned so that animals do n't suffer in the wild . he calls his project `` paradise engineering . '' but is there something sad about a world without sadness ? our cavemen ancestors and favorite poets might not want any part of such a paradise . in fact , the only things about sadness that seem universally agreed upon are that it has been felt by most people throughout time , and that for thousands of years , one of the best ways we have to deal with this difficult emotion is to articulate it , to try to express what feels inexpressable . in the words of emily dickinson , `` 'hope ' is the thing with feathers - that perches in the soul - `` and sings the tune without the words - and never stops - at all - ''
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but your assumption that sadness has an external cause outside the self is a relatively new idea . ancient greek doctors did n't view sadness that way . they believed it was a dark fluid inside the body .
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contemporary ideas about the neurochemical nature of depression has some parallel with ancient greek ideas about melancholy because :
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translator : andrea mcdonough reviewer : bedirhan cinar you 've probably heard of pavlov 's dogs , the phrase that often summarizes dr. ivan pavlov 's early 20th century research , in which he demonstrated that we can alter what stimuli elicit a reflective response in canines . he showed this by sounding a bell just before he presented his group of dogs with meat powder . after many presentations of the bell , followed by tasty meat powder , the dogs eventually began to salivate at just the sound of the bell . they salivated even when there was no meat powder present . this phenomenon is n't limited to dogs . consider the placebo effect , in which a pill with no active substances brings about a response similar to a pill with a substance present . what changes here is our reaction to our ailment , such as perceiving less pain and not the ailment itself . or , consider the love humans have for a parent . some would argue that this love is instinctual , and they may be partially right . but , the argument fails to account for the equal amount of love that children adopted later in life hold for their adoptive parents . but the behaviorist argument can account for both accounts of love . a parent , biological or not , is constantly paired with things like food , smiles , toys , affection , games , protection , and entertainment . and a parent 's constant association with these wonderful or crucial aspects of a child 's life has a similar , albeit more complicated , effect that meat powder had on pavlov 's salivating dogs . in other words , if one 's parent is predictive of really good or really important things , then one 's parent becomes a really good and important thing , too . and there is also romantic advice to be gained from pavlov 's observations . we all need food to survive , right ? and someone who can provide such things in a delicious , saliva-producing manner stands to become our human equivalent of a ringing bell . in other words , if you can cook one or more scrumptious meals for a potential love interest , there 's a good chance that you 'll be viewed more favorably in the future , even if you did n't prepare the delicious food . and who would n't want the love of their life drooling over them ? but life is not just bell rings and salivation . there 's also a dark side to this type of learning , called `` taste aversion '' . taste aversion occurs when we ingest some food that eventually makes us sick , and , as a result , we avoid that food , sometimes for the rest of our lives . taste aversion is so powerful that the effect can be seen even if the illness is experienced hours later and even if the food itself did not actually make us sick . such is the case when we have the flu , and , by accident , we ingest some food moments prior to vomiting . in this case , we know that the food did not cause the vomiting , but our bodies do n't know that . and the next time we encounter that food , we are likely to refuse eating it . now , imagine the potential consequences of undercooking a meal on a first date . if the food makes your date sick , it is possible for them to associate that bad feeling with not just the food , but with < i > your < /i > food in particular . if the episode was traumatizing enough , or if it also happens on a subsequent date , they may come to relate you with the consequences , just like pavlov 's dogs related the bell with the meat powder . in other words , the sight of you showing up at the next dinner date might actually make your date nauseous ! as the old saying goes , the fastest way to someone 's heart is through their stomach , assuming you do n't make them sick in the process .
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and there is also romantic advice to be gained from pavlov 's observations . we all need food to survive , right ? and someone who can provide such things in a delicious , saliva-producing manner stands to become our human equivalent of a ringing bell .
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to make dogs drool at the sound of a bell , one would need to present food :
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it may seem like the semicolon is struggling with an identity crisis . it looks like a comma crossed with a period . maybe that 's why we toss these punctuation marks around like grammatical confetti . we 're confused about how to use them properly . in fact , it 's the semicolon 's half-half status that makes it useful . it 's stronger than a comma , and less final than a period . it fills the spaces in between , and for that reason , it has some specific and important tasks . for one , it can clarify ideas in a sentence that 's already festooned with commas . `` semicolons : at first , they may seem frightening , then , they become enlightening , finally , you 'll find yourself falling for these delightful punctuation marks . '' even though the commas separate different parts of the sentence , it 's easy to lose track of what belongs where . but then the semicolon edges in to the rescue . in list-like sentences , it can exert more force than commas do , cutting sentences into compartments and grouping items that belong together . the semicolon breaks things up , but it also builds connections . another of its tasks is to link together independent clauses . these are sentences that can stand on their own , but when connected by semicolons , look and sound better because they 're related in some way . `` semicolons were once a great mystery to me . i had no idea where to put them . '' technically , there 's nothing wrong with that . these two sentences can stand alone . but imagine they appeared in a long list of other sentences , all of the same length , each separated by periods . things would get monotonous very fast . in that situation , semicolons bring fluidity and variation to writing by connecting related clauses . but as beneficial as they are , semicolons do n't belong just anywhere . there are two main rules that govern their use . firstly , unless they 're being used in lists , semicolons should only connect clauses that are related in some way . you would n't use one here , for instance : `` semicolons were once a great mystery to me ; i 'd really like a sandwich . '' periods work best here because these are two totally different ideas . a semicolon 's job is to reunite two independent clauses that will benefit from one another 's company because they refer to the same thing . secondly , you 'll almost never find a semicolon willingly stationed before coordinating conjunctions : the words , `` and , '' `` but , '' `` for , '' `` nor , '' `` or , '' `` so , '' and `` yet . '' that 's a comma 's place , in fact . but a semicolon can replace a conjunction to shorten a sentence or to give it some variety . ultimately , this underappreciated punctuation mark can give writing clarity , force , and style , all encompassed in one tiny dot and squiggle that 's just waiting to be put in the right place .
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another of its tasks is to link together independent clauses . these are sentences that can stand on their own , but when connected by semicolons , look and sound better because they 're related in some way . `` semicolons were once a great mystery to me .
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which of these is better , and why do you think so ? a. i thoroughly enjoyed the scenery in paris . the eiffel tower is especially beautiful . b. i thoroughly enjoyed the scenery in paris ; the eiffel tower is especially beautiful .
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good morning hank , it 's tuesday . so earlier this morning , i was kayaking on the white river . i came to an island that only exists when the water is low , so i had to choose which stream to follow down . i thought as i always do in these situations of robert frost 's poem , the road not taken . you know , the one that ends in , `` two roads diverged in a yellow wood , and i took the one less travelled by , and that has made all the difference . '' so i followed the road that seemed the less obvious choice . it turns out that it was the less obvious for a reason . so hank , the road not taken is an interesting poem because 1. it 's kind of responsible for the death of the person it was written for and 2. what most people conclude from the poem is the exact opposite of what robert frost intended to conclude . and also , 3. this dissonance points at something terrible about poetry i think hank . but let 's start with 1 - that dead guy . so robert frost was inspired to write this poem by the many walks he took with his friend , the english poet , edward thomas . thomas was very obsessive and indecisive person , and every time they 'd come to a fork in the road , he would n't know which one to take . you know , like how if you 're in the english countryside and if you choose the wrong path , you might get eaten by a lion . but you ca n't know that until after you 've made the choice . i assume that there 'd be lions in england , at least dandy lions . in frost 's mind , the poem was gently mocking people who obsess over the importance of tiny , little decisions , right ? but as often happens with people who are mocked too gently , edward thomas did n't get the joke and took the poem very , very seriously . and so even though edward thomas was too old to be expected to enlist , he went ahead and took the road less travelled , joining the british army to fight in wii , where upon he was promptly shot through the chest and killed . since then hank , pretty much everyone , including me , has adopted edward thomas ' interpretation of the poem despite the fact that it , you know , killed him . i think there 's just something alluring about the idea choosing the less travelled is always a good idea . it would be very helpful if there was some overarching guideline , like `` follow the path that others do n't . '' also , following the road less taken has the added advantage of making everyone feel like a non-conformist , which is nice . but of course , there are a bunch of problems . for one thing , if everyone followed the road less travelled , it quickly becomes the road more travelled . furthermore , there are many times when the road more travelled is more travelled for a reason , because for instance , the road less travelled leads to a kayak unfriendly marsh . or because there 's something kind of nice about having a spouse and two kids and a mini-van . anyways hank , i 've been thinking about this a lot because over at our podcast , dear hank and john , we 've been getting a lot of questions from listeners who are making huge life decisions , you know , should i go into the military ? which college should i attend ? should i attend college at all ? as humans , we constantly have to make all these big , big decisions , with very limited information . like hank , we are both incredibly blessed to have great marriages and great spouses , but i had no idea what i was agreeing to on my wedding day . i thought i was saying , `` i want to be in a romantic relationship with you for the rest of my life . '' i did not realize that i was also saying , `` i want to be co-ceos of a company that raises children and mows lawns and stuff . '' anyways hank , the other thing about dear hank and john is that i insist on beginning each episode with a short poem . and so in the last few weeks , we 've had a bunch of discussions about poetry - whether poetry matters , what poetry does , etc . and i think we have the road not taken as one answer about what poetry can do . because poetry is so often musical and rhythmic , it has a way of sticking in our heads , like i memorized it almost by accident . frost thought that the poem was exploring how people experience choice making rather than offering advice , but precisely because it sounds good hank , it seems like good advice . and even though i know it is n't good advice , at least not consistently , i suspect that the next time i am facing a fork in the road or fork in the river , those iambic feet will wander back into my mind . and i will once again be biased , however minutely , toward the road less travelled . i guess that 's one example of how i think poetry can really matter in the real lives of real people , hank , and why i think that poets and readers alike need to be very careful with language . after all hank , we do n't want to end up like edward thomas , but we also do n't want to end up like the poet , who at least in a roundabout way , killed him . hank , i 'll see you on friday .
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because poetry is so often musical and rhythmic , it has a way of sticking in our heads , like i memorized it almost by accident . frost thought that the poem was exploring how people experience choice making rather than offering advice , but precisely because it sounds good hank , it seems like good advice . and even though i know it is n't good advice , at least not consistently , i suspect that the next time i am facing a fork in the road or fork in the river , those iambic feet will wander back into my mind .
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what did frost think the poem was exploring ?
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hi , everybody ! i am a comparative anatomist . a comparative anatomist is someone who studies the structure of the body of lots of different animals . and my favorite animals are whales . i like to study whales because they 're so interesting . they 've adapted to a unique environment of living in the water . and what i 'm going to tell you about is how whales make sounds by basically farting with their face . you know that they do this farting thing with their blowhole ; they blow out air like that , but they also use air in lots of other ways . they use it for sound production , which is what i 'll focus on , but i also study other things they do with air , like keep it out of their bloodstream so they do n't get bubbles , which is what happens to human scuba divers when they get decompression sickness . but i 'd like to start with the story of how these animals make these farting noises , and that story begins with understanding how hard it is to look at whales , because they live underwater and they 're really big , so they 're hard animals to study . and in this picture -- you see that animal in the middle ? that 's a baby whale and it 's already the size of a bus ! when you look at whales , start with the top of their head because their nose is on the top of their head , kind of like a built-in snorkel . they breathe through that because they 're mammals and mammals breathe air . their nose can be opened and closed , as if you were to pinch it like this . you can see it 's open in the bottom frame , where the red arrows are . but not all whales have two nostrils . whales include the groups of dolphins and porpoises , and dolphins and porpoises , the small whales , have only one nostril on the top of their head , and they open and close that nostril by taking what is essentially an upper lip , like this , and turning it back over their nose , like this . that 's how they open and close their nose . so when they make sounds , what they 're basically doing is a raspberry , ( makes raspberry sound ) which is kind of like a fart , right ? or up in new york , we call it a bronx cheer . and the way they do that is by taking that big , fatty structure of a big fat lip , which , as you can see here in this picture , which is a cut through the middle of a dolphin 's head , that big fat lip is that big yellow portion there , and they roll it back and forth over the top of their nose so that they vibrate it , kind of like when you let the air out of a balloon and it makes that weird vibration sound . so this is what it sounds like when they make their noise : ( vibration noise ) hear it ? he 'll do it again when he faces the camera . ( vibration noise ) sounds like it 's farting underwater . what that dolphin is actually doing , though , is echolocation , which is making these series of pulses , and it uses it like a bat uses sonar . well , a bat uses radar , but when it 's underwater it 's sonar , so this animal is using sonar to see its world in sound . trying to understand how this works , you have to look at it as if you were looking at the amplifier speakers of a sound system . the small-toothed whales are basically the `` tweeters , '' and the sound is coming from that little nose that 's moving back and forth and coming out of their forehead . but the big whales are kind of like the `` woofers , '' the big speakers that you have in an amplifier system . and what 's happening is their sound is coming out of the throat . so if you tried to make sound like a whale -- make a sound right now , and go , `` ahhhhhh . '' ok , now put your hand on your throat , on your adam 's apple . you feel that vibration right there ? that is lost energy for you , because that 's not how you communicate to everybody . you do it out of the mouth . but if you open your mouth underwater , no one will hear you . you have to be able to take this energy and amplify it through the water . that 's what whales do . and when you hear their sound -- ( squeaking sound ) it 's kind of like when you squeak the air out of a balloon . so they get a lot of squeaky noises , but they also have this sound : ( vibrating sound ) it sounds like it 's farting , does n't it ? it 's like it 's got this giant whoopee cushion in its throat . so , how do you know that 's what a whale is doing ? well , we study whales that come to us from strandings . these are animals that die on the beach . small whales like dolphins and porpoises are easy ; we can take them to the lab . but the big whales -- we 've got to bring the lab to the whale . and this is what that looks like . i 'm the one in the middle with the red hat . i 'm not a very tall person , so you can see how big this whale was compared to me . the whale is 65 feet long . and my scalpel is this little tool on the side here . it basically looks like a hockey stick with a blade on the end of it . and doing a dissection of a whale is a very difficult process . you literally have to get into your work . it 's kind of like a giant bloody construction zone . you 're wearing a hard hat , you 're working with heavy machinery . in this case , by the way , that 's just the voice box of a blue whale . just the voice box . i 'm only five feet tall -- you can see it 's like 12 feet long . how do we know what 's going on ? well , we look at the voice box , or larynx , and we see -- this is from a baby whale so it 's much smaller . you see this little u-shaped thing i 've outlined in blue . that 's the part that 's vibrating . it 's kind of like our vocal folds . when i put my hand in there , where that blue sleeve is , you can see there 's a sack underneath it . that 's the whoopee cushion . that 's the air bubble or the balloon . so what these animals are doing -- and you can see , there 's this big black balloon in the throat , where the digestive tract , which is in blue , meets the breathing tract , which is in light blue , and right in the middle is that black sack . these animals are using that sack to make these sounds . and so they vibrate that and send it out . small-toothed whales also have air sacks ; they 're all over their heads , so it 's like they 're airheads . they use this to capture as much air as they can to take down with them when they 're diving , because when you dive , pressures increase , and that decreases the volume of air you have available . but more importantly , having that sack allows them to recycle the air that they 're using , because air is a precious commodity . you do n't want to have to go back up to the surface to get more . so when you make a sound underwater , if you 're a whale -- let 's hear you start making a sound , go `` ahhhh . '' but whales keep their mouths closed , so go `` ahhhmm . '' ( audience makes noise ) you 're all humming , right ? but whales keep their nose closed and go , `` mmmm . '' ( makes noise ) what happened ? you ca n't make the sound anymore once you close your nose because you 've pressurized the system . whales , by having air sacks , keep themselves from pressurizing the system , which means the air continues to flow , and so if you had a bag on the end of your nose , you 'd be able to make air continue to flow . so i hope you 've enjoyed that . that 's what a comparative anatomist does for a living . we study the structure of these animals . we try to mimic it ; we apply it back to the human situation , maybe making new technologies for protective devices or maybe even making new treatments for medicines for people 's diseases who mimic these weird environments . so i hope you enjoyed that . thank you . ( applause )
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they 've adapted to a unique environment of living in the water . and what i 'm going to tell you about is how whales make sounds by basically farting with their face . you know that they do this farting thing with their blowhole ; they blow out air like that , but they also use air in lots of other ways .
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baleen whales , such as blue whales , make sounds by vibrating folds and a sac in the :
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translator : andrea mcdonough reviewer : jessica ruby imagine a world in which you see numbers and letters as colored even though they 're printed in black , in which music or voices trigger a swirl of moving , colored shapes , in which words and names fill your mouth with unusual flavors . jail tastes like cold , hard bacon while derek tastes like earwax . welcome to synesthesia , the neurological phenomenon that couples two or more senses in 4 % of the population . a synesthete might not only hear my voice , but also see it , taste it , or feel it as a physical touch . sharing the same root with anesthesia , meaning no sensation , synesthesia means joined sensation . having one type , such as colored hearing , gives you a 50 % chance of having a second , third , or fourth type . one in 90 among us experience graphemes , the written elements of language , like letters , numerals , and punctuation marks , as saturated with color . some even have gender or personality . for gail , 3 is athletic and sporty , 9 is a vain , elitist girl . by contrast , the sound units of language , or phonemes , trigger synestetic tastes . for james , college tastes like sausage , as does message and similar words with the -age ending . synesthesia is a trait , like having blue eyes , rather than a disorder because there 's nothing wrong . in fact , all the extra hooks endow synesthetes with superior memories . for example , a girl runs into someone she met long ago . `` let 's see , she had a green name . d 's are green : debra , darby , dorothy , denise . yes ! her name is denise ! '' once established in childhood , pairings remain fixed for life . synesthetes inherit a biological propensity for hyperconnecting brain neurons , but then must be exposed to cultural artifacts , such as calendars , food names , and alphabets . the amazing thing is that a single nucleotide change in the sequence of one 's dna alters perception . in this way , synesthesia provides a path to understanding subjective differences , how two people can see the same thing differently . take sean , who prefers blue tasting food , such as milk , oranges , and spinach . the gene heightens normally occurring connections between the taste area in his frontal lobe and the color area further back . but suppose in someone else that the gene acted in non-sensory areas . you would then have the ability to link seemingly unrelated things , which is the definition of metaphor , seeing the similar in the dissimilar . not surprisingly , synesthesia is more common in artists who excel at making metaphors , like novelist vladimir nabokov , painter david hockney , and composers billy joel and lady gaga . but why do the rest of us non-synesthetes understand metaphors like `` sharp cheese '' or `` sweet person '' ? it so happens that sight , sound , and movement already map to one another so closely , that even bad ventriloquists convince us that the dummy is talking . movies , likewise , can convince us that the sound is coming from the actors ' mouths rather than surrounding speakers . so , inwardly , we 're all synesthetes , outwardly unaware of the perceptual couplings happening all the time . cross-talk in the brain is the rule , not the exception . and that sounds like a sweet deal to me !
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jail tastes like cold , hard bacon while derek tastes like earwax . welcome to synesthesia , the neurological phenomenon that couples two or more senses in 4 % of the population . a synesthete might not only hear my voice , but also see it , taste it , or feel it as a physical touch .
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what percentage of the population experiences synesthesia ?
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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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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 .
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how much of the universe is made of dark energy ?
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we like to think of romantic feelings as spontaneous and indescribable things that come from the heart . but it 's actually your brain running a complex series of calculations within a matter of seconds that 's responsible for determining attraction . does n't sound quite as poetic , does it ? but just because the calculations are happening in your brain does n't mean those warm , fuzzy feelings are all in your head . in fact , all five of your senses play a role , each able to vote for , or veto , a budding attraction . the eyes are the first components in attraction . many visual beauty standards vary between cultures and eras , and signs of youth , fertility and good health , such as long lustrous hair , or smooth , scar-free skin , are almost always in demand because they 're associated with reproductive fitness . and when the eyes spot something they like , our instinct is to move closer so the other senses can investigate . the nose 's contribution to romance is more than noticing perfume or cologne . it 's able to pick up on natural chemical signals known as pheromones . these not only convey important physical or genetic information about their source but are able to activate a physiological or behavioral response in the recipient . in one study , a group of women at different points in their ovulation cycles wore the same t-shirts for three nights . after male volunteers were randomly assigned to smell either one of the worn shirts , or a new unworn one , saliva samples showed an increase in testosterone in those who had smelled a shirt worn by an ovulating woman . such a testosterone boost may give a man the nudge to pursue a woman he might not have otherwise noticed . a woman 's nose is particularly attuned to mhc molecules , which are used to fight disease . in this case , opposites attract . when a study asked women to smell t-shirts that had been worn by different men , they preferred the odors of those whose mhc molecules differed from theirs . this makes sense . genes that result in a greater variety of immunities may give offspring a major survival advantage . our ears also determine attraction . men prefer females with high-pitched , breathy voices , and wide formant spacing , correlated with smaller body size . while women prefer low-pitched voices with a narrow formant spacing that suggest a larger body size . and not surprisingly , touch turns out to be crucial for romance . in this experiment , not realizing the study had begun , participants were asked to briefly hold the coffee , either hot or iced . later , the participants read a story about a hypothetical person , and were asked to rate their personality . those who had held the hot cup of coffee perceived the person in the story as happier , more social , more generous and better-natured than those who had held the cup of iced coffee , who rated the person as cold , stoic , and unaffectionate . if a potential mate has managed to pass all these tests , there 's still one more : the infamous first kiss , a rich and complex exchange of tactile and chemical cues , such as the smell of one 's breath , and the taste of their mouth . this magical moment is so critical that a majority of men and women have reported losing their attraction to someone after a bad first kiss . once attraction is confirmed , your bloodstream is flooded with norepinephrine , activating your fight or flight system . your heart beats faster , your pupils dilate , and your body releases glucose for additional energy , not because you 're in danger but because your body is telling you that something important is happening . to help you focus , norepinephrine creates a sort of tunnel vision , blocking out surrounding distractions , possibly even warping your sense of time , and enhancing your memory . this might explain why people never forget their first kiss . the idea of so much of our attraction being influenced by chemicals and evolutionary biology may seem cold and scientific rather than romantic , but the next time you see someone you like , try to appreciate how your entire body is playing matchmaker to decide if that beautiful stranger is right for you .
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and not surprisingly , touch turns out to be crucial for romance . in this experiment , not realizing the study had begun , participants were asked to briefly hold the coffee , either hot or iced . later , the participants read a story about a hypothetical person , and were asked to rate their personality . those who had held the hot cup of coffee perceived the person in the story as happier , more social , more generous and better-natured than those who had held the cup of iced coffee , who rated the person as cold , stoic , and unaffectionate . if a potential mate has managed to pass all these tests , there 's still one more : the infamous first kiss , a rich and complex exchange of tactile and chemical cues , such as the smell of one 's breath , and the taste of their mouth .
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in the coffee study , participants who held the hot coffee rated the hypothetical person as ____________ ?
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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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what ’ s the difference between aspirin and ibuprofen ?
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you 're in line at the grocery store when , uh oh , someone sneezes on you . the cold virus is sucked inside your lungs and lands on a cell on your airway lining . every living thing on earth is made of cells , from the smallest one-celled bacteria to the giant blue whale to you . each cell in your body is surrounded by a cell membrane , a thick flexible layer made of fats and proteins , that surrounds and protects the inner components . it 's semipermeable , meaning that it lets some thing pass in and out but blocks others . the cell membrane is covered with tiny projections . they all have functions , like helping cells adhere to their neighbors or binding to nutrients the cell will need . animal and plant cells have cell membranes . only plant cells have a cell wall , which is made of rigid cellulose that gives the plant structure . the virus cell that was sneezed into your lungs is sneaky . pretending to be a friend , it attaches to a projection on the cell membrane , and the cell brings it through the cell membrane and inside . when the virus gets through , the cell recognizes its mistake . an enemy is inside ! special enzymes arrive at the scene and chop the virus to pieces . they then send one of the pieces back through the cell membrane , where the cell displays it to warn neighboring cells about the invader . a nearby cell sees the warning and immediately goes into action . it needs to make antibodies , proteins that will attack and kill the invading virus . this process starts in the nucleus . the nucleus contains our dna , the blueprint that tells our cells how to make everything our bodies need to function . a certain section of our dna contains instructions that tell our cells how to make antibodies . enzymes in the nucleus find the right section of dna , then create a copy of these instructions , called messenger rna . the messenger rna leaves the nucleus to carry out its orders . the messenger rna travels to a ribosome . there can be as many as 10 million ribosomes in a human cell , all studded along a ribbon-like structure called the endoplasmic reticulum . this ribosome reads the instructions from the nucleus . it takes amino acids and links them together one by one creating an antibody protein that will go fight the virus . but before it can do that , the antibody needs to leave the cell . the antibody heads to the golgi apparatus . here , it 's packed up for delivery outside the cell . enclosed in a bubble made of the same material as the cell membrane , the golgi apparatus also gives the antibody directions , telling it how to get to the edge of the cell . when it gets there , the bubble surrounding the antibody fuses to the cell membrane . the cell ejects the antibody , and it heads out to track down the virus . the leftover bubble will be broken down by the cell 's lysosomes and its pieces recycled over and over again . where did the cell get the energy to do all this ? that 's the roll of the mitochondria . to make energy , the mitochondria takes oxygen , this is the only reason we breathe it , and adds electrons from the food we eat to make water molecules . that process also creates a high energy molecule , called atp which the cell uses to power all of its parts . plant cells make energy a different way . they have chloroplasts that combine carbon dioxide and water with light energy from the sun to create oxygen and sugar , a form of chemical energy . all the parts of a cell have to work together to keep things running smoothly , and all the cells of your body have to work together to keep you running smoothly . that 's a whole lot of cells . scientists think there are about 37 trillion of them .
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every living thing on earth is made of cells , from the smallest one-celled bacteria to the giant blue whale to you . each cell in your body is surrounded by a cell membrane , a thick flexible layer made of fats and proteins , that surrounds and protects the inner components . it 's semipermeable , meaning that it lets some thing pass in and out but blocks others .
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proteins , like antibodies , are made inside of the cell . proteins are made by the cell ’ s :
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imagine being a fossil : touring the world 's great museums , inspiring awe in onlookers of all ages , posing for hordes of fawning photographers . sound like something you 'd like ? well , good luck ! at least 99.9 % of creatures that have ever lived are n't preserved in the fossil record . but forget about them , everyone else will , and listen up ! if you want your corpse in the exclusive 0.01 % club , the hall of preserved fossil fame , it will not be easy . you better work ! step one : die . it 's a cold , hard fact of fossilization . everything paleontologists find was once alive and , at some point , died . we 'll skip the details and assume you had a long , fulfilling life so we can get to what is really important -- how you die . there are many ways to become a fossil , so let 's highlight your top death options . you could get yourself trapped in tree sap , which , when hardens , turns into amber and can survive intact for millions of years . but unless you find a really big tree to sit under , amber preservation will likely remain the domain of insects and other very small animals . generally , the right place to be if you want to end up a fossil is wherever sediment is actively being deposited , like a lake or an ocean floor . a mountaintop or prairie ? not good ! you need to get buried , the faster the better , because the longer you hang around on the surface , the more likely you 'll get eaten , scavenged , or otherwise destroyed before ever having a chance to get preserved . if you can get buried someplace with little to no oxygen , like a bog or a deep lake bottom , even better . that lack of oxygen will slow down your decay and give you more time to fossilize . so , let 's say you 're lucky enough to die and get buried in a shallow sea under muddy , sandy sediments . what 's your next move ? one option is a process called permineralization . while all your soft parts decay away , your bones get saturated with mineral-rich waters . bit by bit , microscopic crystals precipitate out of these waters to fill in the empty spaces and pores in your bones . otherwise , you 'd better hope the sediments around you harden while your bones decay away and another sediment or mineral fills in the spaces your bones leave behind , creating a perfect cast of your skeleton . over time , the sediments around your fossil will lithify or turn into rock . but you 're not in the clear yet ! many things could happen to those sedimentary rocks that might destroy your chances of getting discovered . they could get uplifted into a mountain range and eroded away or carried along in an oceanic plate and subducted back into the earth 's mantle , melting your fossil into hot mush . fingers crossed your rock surroundings will get gently lifted up by plate tectonics , sea levels will change , and you 'll end up under dry land close to the surface , but not so close that erosion from wind and rain wipes you away before someone can come find you . the last step in this long process , an intrepid paleontologist has to come find you . maybe she 's a research scientist scouting for fossils your age and type or just an amateur collector hoping for a fortuitous find . she whacks away at layers of rock above you or spots your fossil exposed in a creek bank after a flood . and there you are , a magnificent scientific discovery , millions of years in the making ! she and her colleagues gently extract you from the surrounding sediment , measure and photograph all the bits and pieces they find , and begin the complex task of reconstructing how and when you lived based on the evidence they find in your bones . paleontologists will be some of your biggest fans along with all those admiring crowds at the museum . you made it ! you spent years underground in obscurity , shedding blood , sweat , tears , and your internal organs . you worked yourself to the bone until your bones disintegrated and were replaced by minerals and sediments . but it was all worth it because you 're a famous fossil ! now , you better hold that pose !
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paleontologists will be some of your biggest fans along with all those admiring crowds at the museum . you made it ! you spent years underground in obscurity , shedding blood , sweat , tears , and your internal organs .
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some types of materials made by organisms get fossilized more easily than others , and some places and environments on earth are more likely to preserve fossils than others . how might these biases affect our view of life through time ?
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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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reshma saujani : yeah . so in 2012 , we taught 20 girls . this year we 'll teach 40,000 in all 50 states .
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what are some practical ways that you think schools can help encourage girls to be brave ?
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some of the best opportunities to learn are the moments in which we are perplexed . those moments in which you begin to wonder and question . these moments have happened throughout history . and have led to some truly amazing discoveries . take this story , for example . there once was a fellow named archimedes . he was born in 287 b.c . in the city of syracuse in sicily . he was a greek mathematician , physicist , engineer , inventor , and astronomer . one day , archimedes was summoned by the king of sicily to investigate if he had been cheated by a goldsmith . the king said he had given a goldsmith the exact amount of gold needed to make a crown . however , when the crown was ready , the king suspected that the goldsmith cheated and slipped some silver into the crown , keeping some of the gold for himself . the king asked archimedes to solve the problem . but there was a catch : he could n't do any damage to the crown . one day , while taking his bath , archimedes noticed that the water level in the bathtub rose and overflowed as he immersed himself into the tub . he suddenly realized that how much water was displaced depended on how much of his body was immersed . this discovery excited him so much that he jumped out of the tub and ran through the streets naked , shouting `` eureka ! '' which comes from the ancient greek meaning `` i found it . '' what did he find ? well , he found a way to solve the king 's problem . you see , archimedes needed to check the crown 's density to see if it was the same as the density of pure gold . density is a measure of an object 's mass divided by its volume . pure gold is very dense , while silver is less dense . so if there was silver in the crown , it would be less dense than if it were made of pure gold . but no matter what it was made of , the crown would be the same shape , which means the same volume . so if archimedes could measure the mass of the crown first , and then measure its volume , he could find out how dense it was . but it is not easy to measure a crown 's volume - it has an irregular shape , that 's different from a simple box or ball . you ca n't measure its size and multiply like you might for other shapes . the solution , archimedes realized , was to give the crown a bath . by placing it in water and seeing how much water was displaced , he could measure the volume , and he 'd calculate the density of the crown . if the crown was less dense than pure gold , then the goldsmith most definitely cheated the king . when archimedes went back to the king and did his test , the story says , he found that the goldsmith had indeed cheated the king , and slipped some silver in . these days , using the way an object displaces water to measure volume is called archimedes ' principle . the next time you take a bath , you can see archimedes ' principle in action , and maybe you 'll have a genius idea of your own .
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those moments in which you begin to wonder and question . these moments have happened throughout history . and have led to some truly amazing discoveries . take this story , for example . there once was a fellow named archimedes . he was born in 287 b.c .
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archimedes is an ancient mathematician and inventor . his discoveries are still important , and we use them today . what is an example of another discovery that archimedes made that is still used today ? name other people from ancient history that have made important discoveries .
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translator : jessica ruby reviewer : caroline cristal they 're long and slithery , and they 're not very colorful . but they do have a strange beauty of their own . their sinuous , nocturnal movements through the water are mesmerizing to watch . and though they may resemble underwater snakes , eels are , in fact , a very interesting type of fish . there are several things about eels that make them unique besides their elongated shape and limbless bodies . for one thing , eels have the ability to breathe through their skin . some can even leave the water and move over land for short periods . and , unlike most migratory fish , such as salmon , which spawn in fresh water but live their adult lives in salt water , eels of the genus anguilla migrate in the opposite direction , spawning and breeding in oceans and seas , while spending most of their intervening time in fresh water . if we were to take one such fresh water eel and follow its life story , it would be born in the middle of the north atlantic ocean , about a thousand miles east of bermuda . this area , called the sargasso sea , forms the western part of a subtropical gyre , a giant whirlpool in the middle of the ocean . our eel , let 's call it eli , would begin as one of ten to twenty million tiny eggs , carried by a female eel , hatching into a transparent leaf-shaped thing that looks nothing like an adult eel . eli starts to drift in ocean currents , predominantly the gulf stream towards either europe or north america , depending on its particular species . upon reaching the coast , eli is about two inches long , looking more eely but still transparent , known at this stage as a glass eel . but within a couple of days in fresh water , eli 's skin becomes pigmented a brownish-black , now looking more like that of an adult eel . you might notice that we have n't mentioned anything about eli 's gender yet . that 's because this is only determined once an eel enters fresh water , though nobody is sure exactly how that happens . most of the eels that stay in the estuaries and brackish water become males , while those that go upstream become females , growing up to two to three times bigger than their future mates . in this case , it turns out that eli was actually short for elaine . as a female eel , elaine will be quite solitary for most of her life in the stream , eating whatever falls in the water : grasshoppers , crickets , small fish , insect larvae , frogs , baby birds , almost anything she can get her mouth around . and she will grow quite big , up to four feet long and weighing as much as thirteen pounds . we do n't know exactly how fresh water eels know when it 's time to return to the ocean , but something calls to them . and their fall migration is one of the largest unseen migrations on the planet . as elaine leaves fresh water for the ocean , she undergoes a shocking metamorphosis . her eyes enlarge by about ten times , her skin gets thicker , and her fins get larger . these are most likely adaptations for their upcoming ocean travel , and elaine seamlessly makes the transition from fresh to salt water , which would be toxic for most other fish . once elaine leaves the mouth of the fresh water streams , she will disappear completely from human view . no one has witnessed , or been able to follow , an adult eel on their migration , nor do we know how deep they spawn . but it 's assumed that they can follow some signs that they can detect , such as a thermal barrier between ocean currents or a salinity front , in order to return to the same area of the ocean where they were born . because we do n't even know exactly what happens during an eel 's migration , we can only imagine what the actual breeding looks like . but the common hypothesis is that elaine and thousands , or hundreds of thousands , of other eels gather in large , intertwined masses and release their eggs and sperm in a giant orgy known as panmixia . a couple of days after the eggs are laid , they hatch , and the cycle begins again . and because we 've never seen the adult eels returning up the fresh water rivers , we must assume that , having completed their long and roundabout journey , these amazing and mysterious creatures finally die there , in the same place where they were born . goodbye , elaine ! it was a pleasure knowing you .
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a couple of days after the eggs are laid , they hatch , and the cycle begins again . and because we 've never seen the adult eels returning up the fresh water rivers , we must assume that , having completed their long and roundabout journey , these amazing and mysterious creatures finally die there , in the same place where they were born . goodbye , elaine !
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we talk a bit about what fresh water eels eat , but many other creatures eat eels , too . what do you think those creatures might be ?
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if insects suddenly morphed into large beings , and decided to wage war on us , there 's no doubt that humans would lose . we 'd simply be crushed by their sheer numbers . there are an estimated 10 quintillion individual insects on earth . that 's a one followed by 19 zeroes . so , compared with our population of about 7 billion , these invertebrates outnumber us by more than a billion to one . their astounding numbers exist at the species level , as well . there are more than 60,000 vertebrate species on the planet . but the class of insects contains a million known species , and many others that have n't been classified . in fact , these critters make up approximately 75 % of all animals on earth . so , what 's their secret to success ? insect abundance comes down to many things that together make them some of the most adaptable and resilient creatures , beginning with their impressive ability to breed . many species can produce hundreds of offspring within their lifetimes . most offspring will die , but more than enough will survive into adulthood to reproduce . offspring also mature very rapidly , so the cycle of reproduction resumes quickly , and can occur over and over again in a short time . these numbers mean that as a class , insects harbor a tremendous amount of genetic diversity . the different species contain a wealth of genetic data that give them the necessary adaptations they need to thrive in a range of environments across the planet . even some of the most extreme environments are in bounds ; flat bark beetles can live at -40 degrees fahrenheit , sahara desert ants can venture out when surface temperatures exceed 155 degrees , and some bumblebees can survive 18,000 feet above sea level . insect exoskeletons also work like body armor , protecting insects against the outside world and helping them cope with habitats that other creatures ca n't . even their small size , which we might see as a disadvantage , is something they use to their benefit . because most species are so tiny , millions of insects can inhabit a small space and make use of all the available resources within it . this means they can occupy hundreds of different niches across ecosystems . some insects survive by eating the roots , stems , leaves , seeds , pollen , and nectar of specific plants . others , like wasps , make use of live insects by paralyzing the victims and laying their eggs inside so that when the hatchlings emerge , they can eat their way out and get nourishment . mosquitos and biting flies feed on blood , taking advantage of this unusual resource to ensure their survival . and a whole bunch of other insects have built a niche around feces . flies lay their eggs there , and some beetles even build large balls out of animal dung , which they eat and use as accommodation for their eggs . and then there 's the insects ' mighty power of metamorphosis . this trait not only transforms insects , but also helps them maximize the available resources in an ecosystem . take butterflies . in their larval caterpillar form , they chomp hungrily through leaves at a rapid rate to help them grow and spin cocoons . but when they emerge as butterflies , these insects feed only on flower nectar . metamorphosis means the larvae and adults of one species will never compete for the same resource , so they successfully share an ecological niche without limiting their own success . this process is so efficient that an incredible 86 % of insect species undergo complete metamorphosis . we 're big and they 're small , so it 's easy to forget that these critters are moving in their millions all around us , all the time . but examine almost any patch of ground , and you 're sure to find them there . their numbers are immense , and their success is unmatched . we may have to accept that it 's insects , not us , that are the true conquerors of the planet .
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if insects suddenly morphed into large beings , and decided to wage war on us , there 's no doubt that humans would lose . we 'd simply be crushed by their sheer numbers .
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insects , unlike humans and other vertebrates , have an exoskeleton . this means their skeleton is on the outside instead of the inside , like us . how do you think insects manage to grow bigger if they are encased in an exoskeleton ?
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indium is a very soft metal . i haven ’ t got a sample here . it melts at 150 degrees or so . this is an example of indium it is a really , really quite nice chemical element this one . we can use it for lots and lots of selective types of catalysis , but generally when it is forming a complex with other organic ligands . but here we can see a really nice example of indium and this is 99.9 % pure . but it ’ s a metal which has suddenly become very much more expensive because its oxide is transparent to light but will conduct electricity . so it is indium oxide that you find on every lcd display . here is a rather old computer and here is an old fashioned computer , the lcd display was quite small and gradually they have got bigger and bigger and therefore demand for indium oxide is more and more and probably you are watching this video clip through a thin layer of indium oxide . this sample although it ’ s very small , is 5 grams . so it is a really , really , dense metal , very , very expensive and very , very valuable as well . but indium is also used as solder for soldering various metals together and it is also quite useful if , i used it in my youth , when we were making low temperature apparatus and we wanted to screw two things together and get a nice seal in between them , you could screw them together with a thin sheet of indium , and that almost welded them together . so indium wire ; it is very , very malleable and very , very soft and very easy to form into shapes . i am not going to touch it though because it will cause some significant problems for me , because it does cause toxicity if it comes into contact with the skin ; so lovely piece of indium wire .
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indium is a very soft metal . i haven ’ t got a sample here .
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indium is a ...
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you might remember a pair of ted-ed lessons written and performed by two educators , brad voytek and tim verstynen . these two scientists used a drooling , hag-faced , animated zombie as a mechanism to model the symptoms and medical diagnosis process for various neurological conditions . for example , they spent time debating whether the zombie 's stiff gait was caused by basal ganglia damage , like that in parkinson 's patients , or by severe damage to the cerebellum , which can cause ataxia . in each lesson , brad and tim certainly showed us how the walking dead can help us understand neuroscience , but how can the walking dead help us understand animation ? or , more simply put , how did this one-eyed , decaying , and very much dead pile of pixels walk ? puppet animation is a relatively quick solution to creating 2-d animation of a hand-drawn character . since the character does not need to be drawn over and over again , it can be animated by moving each element individually . aside from their portrayal in a few great modern zombie flicks , these concocted carcasses are generally known for limited , stiff movements . their traditional stride is perfect for puppet-style animation . when designing a 2-d zombie puppet , or any other type of puppet , it is important to find a design that is both fun and functional in a flat environment . for example , you might not want to puppetize , say , julie andrews in the `` sound of music '' as she spins in circles . we used rotoscoping for her , but that 's another lesson . always begin by sketching and designing your puppet in a neutral pose like this . this will allow it to easily transition into and out of a variety of extreme positions . once a character transitions from concept stetches to final design , the next step is to break up the pieces in order to assemble a puppet , keeping in mind that each element needs to have an appropriate amount of overlap so that the zombie can bend at his joints . an understanding of anatomy is an integral part of designing any 2-d or 3-d animated character that needs to move realistically in the context of its environment . regardless of the number of dimensions your character has , you 'll need to create a skeleton , which in animation terms is known as a rig . once the rig is finalized and the range of motion is determined , the next step is to choose anchor points . each piece of artwork has its own anchor point , which essentially assigns the limb a hinge , which in this case is a joint . next , line the artwork up so that the anchor point for the forearm-elbow sits on the upper arm 's elbow area . once all the artwork is in place , you can use an expression script that creates links between the body parts . in this case , we used the expressions provided in after effects . by parenting one layer to another , you could teach the forearm to follow the upper arm and the hand to follow the forearm . this is what 's called forward kinematics . the alternative is inverse kinematics , in which a separate set of scripts control the motions . in this case , a controller is attached to the anchor point of the hand . the animator then uses the controller to position the hand . the scripts will then use an algorithm to make sure that the rest of the arm and body follows along . once the character is rigged , we can start animating . often times , puppet animation is done as straight-ahead action , which means moving a character frame-by-frame from beginning to end . another approach is pose-to-pose animation , which involves choosing your key poses first , and then filling in the intervals , or in-betweens , later . regardless of the method of motion , it 's important to think of your 2-d puppet as a piece of paper . it can move across a surface in a variety of poses , but it can not move in perspective . if your character needs to turn its head , then you will need to create additional art . we created three different zombie heads and six different hands to achieve different movements and angles that the neutral pose could n't accommodate . you can recreate almost everything you 've seen in this lesson with a pen , paper , and a camera . the method is called cut-out animation , and it was around well before the age of software . to create a stumbling 2-d zombie , or a speeding narwhal , or even an abstract character with some semblance of joints , simply print , cut , and fasten your character 's limbs together in a neutral pose . you can use fasteners , string , or even just place and move them each time . all the same rules and theories that we use in the computer apply to cut-out animation , except under the camera , the only way to animate is straight ahead .
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an understanding of anatomy is an integral part of designing any 2-d or 3-d animated character that needs to move realistically in the context of its environment . regardless of the number of dimensions your character has , you 'll need to create a skeleton , which in animation terms is known as a rig . once the rig is finalized and the range of motion is determined , the next step is to choose anchor points .
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regardless of the number of dimensions your character has , you ’ ll need to create a skeleton , which in animation terms is known as what ?
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many generations have felt they 've reached the pinnacle of technological advancement , yet look back 100 years , and the technologies we take for granted today would seem like impossible magic . so will there be a point where we reach an actual limit of technological progress ? and if so , are we anywhere near that limit now ? half a century ago , russian astronomer nikolai kardashev was asking similar questions when he came up with a way to measure technological progress , even when we have no idea exactly what it might look like . anything we do in the future will require energy , so kardashev 's scale classifies potential civilizations , whether alien civilizations out there in the universe or our own , into three levels based on energy consumption . the tiny amount of energy we currently consume pales next to what we leave untapped . a type i , or planetary civilization , can access all the energy resources of its home planet . in our case , this is the 174,000 terawatts earth receives from the sun . we currently only harness about 15 terawatts of it , mostly by burning solar energy stored in fossil fuels . to approach becoming a type i civilization , we would need to capture solar energy more directly and efficiently by covering the planet with solar panels . based on the most optimistic models , we might get there within just four centuries . what would be next ? well , the earth only gets a sliver of the sun 's energy , while the rest of its 400 yottawatts is wasted in dead space . but a type ii , or stellar civilization , would make the most of its home star 's energy . instead of installing solar panels around a planet , a type ii civilization would install them directly orbiting its star , forming a theoretical structure called a dyson sphere . and the third step ? a type iii civilization would harness all the energy of its home galaxy . but we can also think of progress in the opposite way . how small can we go ? to that end , british cosmologist john barrow classified civilizations by the size of objects they control . that ranges from mechanical structures at our own scale , to the building blocks of our own biology , down to unlocking atoms themselves . we 've currently touched the atomic level , though our control remains limited . but we potentially could go much smaller in the future . to get a sense of the extent to which that 's true , the observable universe is 26 orders of magnitude larger than a human body . that means if you zoomed out by a factor of ten 26 times , you 'd be at the scale of the universe . but to reach the minimum length scale , known as the planck length , you would need to zoom in 35 times . as physicist richard feynman once said , `` there 's plenty of room at the bottom . '' instead of one or the other , it 's likely that our civilization will continue to develop along both kardashev and barrow scales . precision on a smaller scale lets us use energy more efficiently and unlocks new energy sources , like nuclear fusion , or even antimatter . and this increased energy lets us expand and build on a larger scale . a truly advanced civilization , then , would harness both stellar energy and subatomic technologies . but these predictions were n't made just for us humans . they double as a possible means of detecting intelligent life in the universe . if we find a dyson sphere around a distant star , that 's a pretty compelling sign of life . or , what if , instead of a structure that passively soaked up all the star 's energy , like a plant , an alien civilization built one that actively sucked the energy out of the star like a hummingbird . frighteningly enough , we 've observed super dense celestial bodies about the size of a planet that drain energy out of a much bigger star . it would be much too premature to conclude that this is evidence of life in the universe . there are also explanations for these observations that do n't involve alien life forms . but that does n't stop us from asking , `` what if ? ''
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they double as a possible means of detecting intelligent life in the universe . if we find a dyson sphere around a distant star , that 's a pretty compelling sign of life . or , what if , instead of a structure that passively soaked up all the star 's energy , like a plant , an alien civilization built one that actively sucked the energy out of the star like a hummingbird .
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what are the pros and cons of both a dyson sphere and active energy extraction from a star ?
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communicating underwater is challenging . light and odors do n't travel well , so it 's hard for animals to see or smell . but sound moves about four times faster in water than in air , so in this dark environment , marine mammals often rely on vocalization to communicate . that 's why a chorus of sounds fills the ocean . clicks , pulses , whistles , groans , boings , cries , and trills , to name a few . but the most famous parts of this underwater symphony are the evocative melodies , or songs , composed by the world 's largest mammals , whales . whale songs are one of the most sophisticated communication systems in the animal kingdom . only a few species are known to sing . blue , fin , bowhead minke whales , and of course humpback whales . these are all baleen whales which use hairy baleen plates instead of teeth to trap their prey . meanwhile , toothed whales do use echolocation , and they and other species of baleen whales make social sounds , such as cries and whistles , to communicate . but those vocalizations lack the complexity of songs . so how do they do it ? land mammals like us generate sound by moving air over our vocal cords when we exhale , causing them to vibrate . baleen whales have a u-shaped fold of tissue between their lungs and their large inflatable organs called laryngeal sacs . we do n't know this for sure because it 's essentially impossible to observe the internal organs of a living , singing whale , but we think that when a whale sings , muscular contractions in the throat and chest move air from the lungs across the u-fold and into the laryngeal sacs , causing the u-fold to vibrate . the resulting sound resonates in the sacs like a choir singing in a cathedral making songs loud enough to propagate up to thousands of kilometers away . whales do n't have to exhale to sing . instead , the air is recycled back into the lungs , creating sound once more . one reason whale songs are so fascinating is their pattern . units , like moans , cries , and chirps are arranged in phrases . repeated phrases are assembled into themes . multiple themes repeated in a predictable pattern create a song . this hierarchical structure is a kind of grammar . whale songs are extremely variable in duration , and whales can repeat them over and over . in one recorded session , a humpback whale sang for 22 hours . and why do they do it ? we do n't yet know the exact purpose , but we can speculate . given that the singers are males and they mostly sing during the mating season , songs might be used to attract females . or perhaps they 're territorial , used to deter other males . whales return to the same feeding and breeding grounds annually , and each discrete population has a different song . songs evolve over time as units or phrases are added , changed , or dropped . and when males from different populations are feeding within earshot , phrases are often exchanged , maybe because new songs make them more attractive to breeding females . this is one of the fastest examples of cultural transmission , where learned behaviors are passed between unrelated individuals of the same species . we can eavesdrop on these songs using underwater microphones called hydrophones . these help us track species when sightings or genetic samples are rare . for example , scientists have been able to differentiate the elusive blue whale 's populations worldwide based on their songs . but the oceans are getting noisier as a result of human activity . boating , military sonar , underwater construction , and seismic surveys for oil are occurring more often which may interfere with whale 's communication . some whales will avoid key feeding or breeding grounds if human noise is too loud . and humpback whales have been observed to reduce their singing in response to noise 200 kilometers away . limiting human activity along migratory routes and in other critical habitats , and reducing noise pollution throughout the ocean would help ensure whales continued survival . if the whales can keep singing and we can keep listening , maybe one day we 'll truly understand what they 're saying .
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only a few species are known to sing . blue , fin , bowhead minke whales , and of course humpback whales . these are all baleen whales which use hairy baleen plates instead of teeth to trap their prey .
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which whales are most famous for singing ?
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have you ever noticed something swimming in your field of vision ? it may look like a tiny worm or a transparent blob , and whenever you try to get a closer look , it disappears , only to reappear as soon as you shift your glance . but do n't go rinsing out your eyes ! what you are seeing is a common phenomenon known as a floater . the scientific name for these objects is muscae volitantes , latin for `` flying flies , '' and true to their name , they can be somewhat annoying . but they 're not actually bugs or any kind of external objects at all . rather , they exist inside your eyeball . floaters may seem to be alive , since they move and change shape , but they are not alive . floaters are tiny objects that cast shadows on the retina , the light-sensitive tissue at the back of your eye . they might be bits of tissue , red blood cells , or clumps of protein . and because they 're suspended within the vitreous humor , the gel-like liquid that fills the inside of your eye , floaters drift along with your eye movements , and seem to bounce a little when your eye stops . floaters may be only barely distinguishable most of the time . they become more visible the closer they are to the retina , just as holding your hand closer to a table with an overhead light will result in a more sharply defined shadow . and floaters are particularly noticeable when you are looking at a uniform bright surface , like a blank computer screen , snow , or a clear sky , where the consistency of the background makes them easier to distinguish . the brighter the light is , the more your pupil contracts . this has an effect similar to replacing a large diffuse light fixture with a single overhead light bulb , which also makes the shadow appear clearer . there is another visual phenomenon that looks similar to floaters but is in fact unrelated . if you 've seen tiny dots of light darting about when looking at a bright blue sky , you 've experienced what is known as the blue field entoptic phenomenon . in some ways , this is the opposite of seeing floaters . here , you are not seeing shadows but little moving windows letting light through to your retina . the windows are actually caused by white blood cells moving through the capillaries along your retina 's surface . these leukocytes can be so large that they nearly fill a capillary causing a plasma space to open up in front of them . because the space and the white blood cells are both more transparent to blue light than the red blood cells normally present in capillaries , we see a moving dot of light wherever this happens , following the paths of your capillaries and moving in time with your pulse . under ideal viewing conditions , you might even see what looks like a dark tail following the dot . this is the red blood cells that have bunched up behind the leukocyte . some science museums have an exhibit which consists of a screen of blue light , allowing you to see these blue sky sprites much more clearly than you normally would . while everybody 's eyes experience these sort of effects , the number and type vary greatly . in the case of floaters , they often go unnoticed , as our brain learns to ignore them . however , abnormally numerous or large floaters that interfere with vision may be a sign of a more serious condition , requiring immediate medical treatment . but the majority of the time entoptic phenomena , such as floaters and blue sky sprites , are just a gentle reminder that what we think we see depends just as much on our biology and minds as it does on the external world .
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they might be bits of tissue , red blood cells , or clumps of protein . and because they 're suspended within the vitreous humor , the gel-like liquid that fills the inside of your eye , floaters drift along with your eye movements , and seem to bounce a little when your eye stops . floaters may be only barely distinguishable most of the time .
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in what part of the eye do `` floaters '' occur ?
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after the french revolution erupted in 1789 , europe was thrown into chaos . neighboring countries ' monarchs feared they would share the fate of louis xvi , and attacked the new republic , while at home , extremism and mistrust between factions lead to bloodshed . in the midst of all this conflict , a powerful figure emerged to take charge of france . but did he save the revolution or destroy it ? `` order , order , who 's the defendant today ? i do n't see anyone . '' `` your honor , this is napoléon bonaparte , the tyrant who invaded nearly all of europe to compensate for his personal stature-based insecurities . '' `` actually , napoléon was at least average height for his time . the idea that he was short comes only from british wartime propaganda . and he was no tyrant . he was safeguarding the young republic from being crushed by the european monarchies . '' `` by overthrowing its government and seizing power himself ? '' `` your honor , as a young and successful military officer , napoléon fully supported the french revolution , and its ideals of liberty , equality , and fraternity . but the revolutionaries were incapable of real leadership . robespierre and the jacobins who first came to power unleashed a reign of terror on the population , with their anti-catholic extremism and nonstop executions of everyone who disagreed with them . and the directory that replaced them was an unstable and incompetent oligarchy . they needed a strong leader who could govern wisely and justly . '' `` so , france went through that whole revolution just to end up with another all-powerful ruler ? '' `` not quite . napoléon 's new powers were derived from the constitution that was approved by a popular vote in the consulate . '' `` ha ! the constitution was practically dictated at gunpoint in a military coup , and the public only accepted the tyrant because they were tired of constant civil war . '' `` be that as it may , napoléon introduced a new constitution and a legal code that kept some of the most important achievements of the revolution in tact : freedom of religion abolition of hereditary privilege , and equality before the law for all men . '' `` all men , indeed . he deprived women of the rights that the revolution had given them and even reinstated slavery in the french colonies . haiti is still recovering from the consequences centuries later . what kind of equality is that ? '' `` the only kind that could be stably maintained at the time , and still far ahead of france 's neighbors . '' `` speaking of neighbors , what was with all the invasions ? '' `` great question , your honor . '' `` which invasions are we talking about ? it was the neighboring empires who had invaded france trying to restore the monarchy , and prevent the spread of liberty across europe , twice by the time napoléon took charge . having defended france as a soldier and a general in those wars , he knew that the best defense is a good offense . '' `` an offense against the entire continent ? peace was secured by 1802 , and other european powers recognized the new french regime . but bonaparte could n't rest unless he had control of the whole continent , and all he knew was fighting . he tried to enforce a european-wide blockade of britain , invaded any country that did n't comply , and launched more wars to hold onto his gains . and what was the result ? millions dead all over the continent , and the whole international order shattered . '' `` you forgot the other result : the spread of democratic and liberal ideals across europe . it was thanks to napoléon that the continent was reshaped from a chaotic patchwork of fragmented feudal and religious territories into efficient , modern , and secular nation states where the people held more power and rights than ever before . '' `` should we also thank him for the rise of nationalism and the massive increase in army sizes ? you can see how well that turned out a century later . '' `` so what would european history have been like if it were n't for napoléon ? '' `` unimaginably better/worse . '' napoléon seemingly unstoppable momentum would die in the russian winter snows , along with most of his army . but even after being deposed and exiled , he refused to give up , escaping from his prison and launching a bold attempt at restoring his empire before being defeated for the second and final time . bonaparte was a ruler full of contradictions , defending a popular revolution by imposing absolute dictatorship , and spreading liberal ideals through imperial wars , and though he never achieved his dream of conquering europe , he undoubtedly left his mark on it , for better or for worse .
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he was safeguarding the young republic from being crushed by the european monarchies . '' `` by overthrowing its government and seizing power himself ? '' `` your honor , as a young and successful military officer , napoléon fully supported the french revolution , and its ideals of liberty , equality , and fraternity .
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how did napoleon actually come to power ?
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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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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 .
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how does sensing stress get communicated throughout your body ?
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they say , 'time is money , ' but what does one really have to do with the other ? meet sheila ! she just got her first big bonus . sheila knows exactly what she wants to do with that money . she 's had her eye on a nice convertible for a while now . yes , sheila , that 's a nice car ! oh , looks like sheila is a little short . but wait ! she has an idea . sheila is a smart cookie . she knows that if she deposits the money for a year instead of buying the car today , she will earn interest . then she 'll be able to afford the car . sheila knows that the value of her deposit one year from now will equal the money deposited today plus the interest earned . we call sheila 's money deposited today the present value of money . and the value of sheila 's deposit next year is the future value of money . what connects one to the other ? the interest rate , also known as the time value of money . now , with a little bit of rearranging , we can figure out the future value of sheila 's money with this equation . so in a year , the future value will be $ 11,000 . well , it 's been a year ! and there 's sheila , with enough money to buy the car . sheila really understands the future value of money . now , i just hope she understands the speed limit ! now , meet timmy . he 's also gotten his bonus . the money seems to be burning a hole in his pocket . yes , timmy , that 's a nice car that will surely impress people . oh ! looks like you 're a little short . maybe you can follow sheila 's example . you see , timmy , just like sheila , after the first year , you 'll have $ 11,000 . but timmy , that is still not enough to buy that fancy car . why do n't you leave the money deposited for another year ? let 's see how your deposit will be doing in two years . with a little bit of rearranging , it becomes the value of your money next year , times one plus the interest rate . we can then convert the future value one year from now to the present value times one plus the interest rate . we can even simplify this further by just squaring the value of one plus the interest rate . sorry , timmy , you 'll have more money after two years , but you still ca n't afford the car ! i do n't know how many more years you 'll have to wait , but i can tell you one way we can figure it out . do you see that little number two in the equation ? any number that you put in there is the number of years that you are waiting , also known as the period . sure , timmy , we can see how much you 'll have in five years . let 's connect future value and present value across five years . let 's watch the period increase from two to five . after 5 years , you 'll have $ 16,105.10 . sorry , timmy , you have to wait a little longer . 10 years ? yeah ! let 's see if you 'll be able to buy the car then . not quite . well , timmy , it looks like you 'll need 26 years to afford this car . you should ask sheila for a ride to the beach . maybe a bicycle will suit you better ? i hear the bus is pretty cheap !
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sure , timmy , we can see how much you 'll have in five years . let 's connect future value and present value across five years . let 's watch the period increase from two to five .
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could you , using the concepts we learned linking present value and future value , determine the implied interest rate needed to make a value of $ 10,000 today ( present value ) , equal $ 11,000 ( future value ) , one year from now ?
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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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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 .
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the secret of life . the double helix . the building block of life . deoxyribonucleic acid . these are all names for what is most commonly known as dna . if you had to rename the molecule , what would you call it and why ? explain why dna has so many names .
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acids and bases are everywhere . they 're used to make foods , soaps and detergents , fertilizers , explosives , dyes , plastics , pesticides , even paper . our stomachs are very acidic . our blood is slightly basic . our proteins are made up of amino acids , and the letters in our genetic code , those as , ts , cs , and gs , are all bases . you were probably taught how acids and bases behave on the molecular level . you were probably never taught that a long time ago , like ancient greek ago , before anyone knew about atoms or molecules , acids and bases were defined by how they behaved . acids tasted sour and corroded metal . bases felt slippery and could somehow counteract acids . when molecules dissolved in water interact , they are exchanging two main currencies with their surroundings : protons , also known as hydrogen ions , and electrons . depending on how a molecule is composed or shaped , it may be willing to donate or accept either protons or electrons with some other community member . and some molecules are far more aggressive than others when it comes to donating or accepting either currency . remember that protons are positively charged and electrons are negatively charged . so , if a molecule is willing to give up a proton , that 's not too different from it being willing to accept an electron -- either way it 's becoming more negatively charged . other molecules are willing to accept a proton or give up an electron . these are becoming more positively charged . some substances are so aggressive about donating their protons that when they get a chance , all of the molecules in a sample will dump a proton , sometimes more than one , to the surrounding water molecules . we call these strong acids . meanwhile , some compounds are so ready to accept a proton that they wo n't wait around , they 'll just rip one off water , which usually has two protons but is generous enough to hang out with just one . we call these strong bases . other acids and bases are not so strong . they may donate just a few of their protons to water or accept just a few protons from water , but most of their molecules stay exactly the same . if left alone in water , they 'll reach some equilibrium point where maybe only one out of a hundred or one out of ten thousand of their molecules has exchanged currency with water . as you might guess , we label these acids and bases weak , but in the common sense of the word , they 're not weak . the vinegar in your salad dressing that you can smell from across the room , that is a weak acid . the ammonia you spray on glass for a streak-free shine , that is a weak base . so , it does n't take much to be an active player in the chemical economy . most acid-base chemistry takes place in water , which can act as either an acid or a base , accepting deposits and enabling withdrawals like a 24-hour molecular atm . and when a proton-deposit customer , that 's an acid , and a proton-withdrawal customer , the base , shop at the same time , their net effect on water 's account may cancel out , and we call this neutralization . now , certain molecules can behave as acids or bases without water , but that 's another story . let 's end by saluting water as the resilient and fair banker for acids and bases . it 's always open for business , does n't charge interest , and will never foreclose on your molecules , which is more than i can say for [ bleep ] . waah-waah .
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acids and bases are everywhere . they 're used to make foods , soaps and detergents , fertilizers , explosives , dyes , plastics , pesticides , even paper .
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which of the following statements is true :
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it 's not hard to imagine a world where at any given moment , you and everyone you know could be wiped out without warning at the push of a button . this was the reality for millions of people during the 45-year period after world war ii , now known as the cold war . as the united states and soviet union faced off across the globe , each knew that the other had nuclear weapons capable of destroying it . and destruction never loomed closer than during the 13 days of the cuban missile crisis . in 1961 , the u.s. unsuccessfully tried to overthrow cuba 's new communist government . that failed attempt was known as the bay of pigs , and it convinced cuba to seek help from the u.s.s.r. soviet premier nikita khrushchev was happy to comply by secretly deploying nuclear missiles to cuba , not only to protect the island , but to counteract the threat from u.s. missiles in italy and turkey . by the time u.s. intelligence discovered the plan , the materials to create the missiles were already in place . at an emergency meeting on october 16 , 1962 , military advisors urged an airstrike on missile sites and invasion of the island . but president john f. kennedy chose a more careful approach . on october 22 , he announced that the the u.s. navy would intercept all shipments to cuba . there was just one problem : a naval blockade was considered an act of war . although the president called it a quarantine that did not block basic necessities , the soviets did n't appreciate the distinction . in an outraged letter to kennedy , khrushchev wrote , `` the violation of freedom to use international waters and international airspace is an act of aggression which pushes mankind toward the abyss of world nuclear missile war . '' thus ensued the most intense six days of the cold war . while the u.s. demanded the removal of the missiles , cuba and the u.s.s.r insisted they were only defensive . and as the weapons continued to be armed , the u.s. prepared for a possible invasion . on october 27 , a spy plane piloted by major rudolph anderson was shot down by a soviet missile . the same day , a nuclear-armed soviet submarine was hit by a small-depth charge from a u.s. navy vessel trying to signal it to come up . the commanders on the sub , too deep to communicate with the surface , thought war had begun and prepared to launch a nuclear torpedo . that decision had to be made unanimously by three officers . the captain and political officer both authorized the launch , but vasili arkhipov , second in command , refused . his decision saved the day and perhaps the world . but the crisis was n't over . for the first time in history , the u.s. military set itself to defcon 2 , the defense readiness one step away from nuclear war . with hundreds of nuclear missiles ready to launch , the metaphorical doomsday clock stood at one minute to midnight . but diplomacy carried on . in washington , d.c. , attorney general robert kennedy secretly met with soviet ambassador anatoly dobrynin . after intense negotiation , they reached the following proposal . the u.s. would remove their missiles from turkey and italy and promise to never invade cuba in exchange for the soviet withdrawal from cuba under u.n. inspection . once the meeting had concluded , dobrynin cabled moscow saying time is of the essence and we should n't miss the chance . and at 9 a.m. the next day , a message arrived from khrushchev announcing the soviet missiles would be removed from cuba . the crisis was now over . while criticized at the time by their respective governments for bargaining with the enemy , contemporary historical analysis shows great admiration for kennedy 's and khrushchev 's ability to diplomatically solve the crisis . but the disturbing lesson was that a slight communication error , or split-second decision by a commander , could have thwarted all their efforts , as it nearly did if not for vasili arkhipov 's courageous choice . the cuban missile crisis revealed just how fragile human politics are compared to the terrifying power they can unleash .
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on october 22 , he announced that the the u.s. navy would intercept all shipments to cuba . there was just one problem : a naval blockade was considered an act of war . although the president called it a quarantine that did not block basic necessities , the soviets did n't appreciate the distinction . in an outraged letter to kennedy , khrushchev wrote , `` the violation of freedom to use international waters and international airspace is an act of aggression which pushes mankind toward the abyss of world nuclear missile war . ''
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the united states called the blockade a quarantine because :
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translator : andrea mcdonough reviewer : bedirhan cinar dear subscribers , there are over 250,000 of you now , a critical mass at a critical time . we have the cumulative potential to impact global education . i 've been assembled and given a voice for this video to describe one way to do just that . please allow me 2.5 minutes to explain . my name is ted-ed and i am a symbol for both the ted-ed website and the billions of videos available to you for free on the website known as `` youtube '' . today i invite you on a journey on which you will learn how to use ed.ted.com to create a lesson around the vast majority of videos on the web . when i say , `` create a lesson , '' i mean that you may use the ted-ed website to search for any video on youtube . once you find the perfect video , the one that really blows your hair back , helps you understand , or that makes you pause and say , `` my goodness , the universe is a fascinating place ! `` , you may use ted-ed to enhance that video . you might use the `` let 's begin '' section to set context for interpreting the video or to define a learning objective for your students . or , you might use the `` think '' section to add multiple choice questions with time-coded video hints or open answer questions that beg for thought-provoking , written responses . or , perhaps you 'll use the `` dig deeper '' section to expand upon the video with articles , references , or links to an application , or maybe even your blog . if any feature is not your cup of tea , just click `` exclude '' . and this new feature , `` discuss , '' it lets you create riveting discussions around your favorite bits . learners , you can engage with lessons independently . the site will save your answers , notes , and ideas to your personal profile and track your learning over time . new lessons are added every day . teachers , as you build or distribute customized lessons to individuals or to groups , you may use the site to track the progress of single students or your entire class . and no matter who you are , if you take the time to create a particularly stunning lesson , please also take the time to nominate it . we will systematically feature the best community-made lessons within the ever-growing ted-ed library , free for the world to learn from , to customize and to share . the possibilities of this tool are as infinite as youtube itself . and , we will be adding new features regularly in the months and years to come . to join me and many others in building a library of lessons worth sharing , simply click on one of the features that interests you . thank you for your time .
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today i invite you on a journey on which you will learn how to use ed.ted.com to create a lesson around the vast majority of videos on the web . when i say , `` create a lesson , '' i mean that you may use the ted-ed website to search for any video on youtube . once you find the perfect video , the one that really blows your hair back , helps you understand , or that makes you pause and say , `` my goodness , the universe is a fascinating place !
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if you could make an improvement to the lesson , what would it be ?
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when we talk about english , we often think of it as a single language but what do the dialects spoken in dozens of countries around the world have in common with each other , or with the writings of chaucer ? and how are any of them related to the strange words in beowulf ? the answer is that like most languages , english has evolved through generations of speakers , undergoing major changes over time . by undoing these changes , we can trace the language from the present day back to its ancient roots . while modern english shares many similar words with latin-derived romance languages , like french and spanish , most of those words were not originally part of it . instead , they started coming into the language with the norman invasion of england in 1066 . when the french-speaking normans conquered england and became its ruling class , they brought their speech with them , adding a massive amount of french and latin vocabulary to the english language previously spoken there . today , we call that language old english . this is the language of beowulf . it probably does n't look very familiar , but it might be more recognizable if you know some german . that 's because old english belongs to the germanic language family , first brought to the british isles in the 5th and 6th centuries by the angles , saxons , and jutes . the germanic dialects they spoke would become known as anglo-saxon . viking invaders in the 8th to 11th centuries added more borrowings from old norse into the mix . it may be hard to see the roots of modern english underneath all the words borrowed from french , latin , old norse and other languages . but comparative linguistics can help us by focusing on grammatical structure , patterns of sound changes , and certain core vocabulary . for example , after the 6th century , german words starting with `` p , '' systematically shifted to a `` pf '' sound while their old english counterparts kept the `` p '' unchanged . in another split , words that have `` sk '' sounds in swedish developed an `` sh '' sound in english . there are still some english words with `` sk , '' like `` skirt , '' and `` skull , '' but they 're direct borrowings from old norse that came after the `` sk '' to `` sh '' shift . these examples show us that just as the various romance languages descended from latin , english , swedish , german , and many other languages descended from their own common ancestor known as proto-germanic spoken around 500 b.c.e . because this historical language was never written down , we can only reconstruct it by comparing its descendants , which is possible thanks to the consistency of the changes . we can even use the same process to go back one step further , and trace the origins of proto-germanic to a language called proto-indo-european , spoken about 6000 years ago on the pontic steppe in modern day ukraine and russia . this is the reconstructed ancestor of the indo-european family that includes nearly all languages historically spoken in europe , as well as large parts of southern and western asia . and though it requires a bit more work , we can find the same systematic similarities , or correspondences , between related words in different indo-european branches . comparing english with latin , we see that english has `` t '' where latin has `` d '' , and `` f '' where latin has `` p '' at the start of words . some of english 's more distant relatives include hindi , persian and the celtic languages it displaced in what is now britain . proto-indo-european itself descended from an even more ancient language , but unfortunately , this is as far back as historical and archeological evidence will allow us to go . many mysteries remain just out of reach , such as whether there might be a link between indo-european and other major language families , and the nature of the languages spoken in europe prior to its arrival . but the amazing fact remains that nearly 3 billion people around the world , many of whom can not understand each other , are nevertheless speaking the same words shaped by 6000 years of history .
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but comparative linguistics can help us by focusing on grammatical structure , patterns of sound changes , and certain core vocabulary . for example , after the 6th century , german words starting with `` p , '' systematically shifted to a `` pf '' sound while their old english counterparts kept the `` p '' unchanged . in another split , words that have `` sk '' sounds in swedish developed an `` sh '' sound in english . there are still some english words with `` sk , '' like `` skirt , '' and `` skull , '' but they 're direct borrowings from old norse that came after the `` sk '' to `` sh '' shift .
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words that start with a `` pf '' sound in german start with _____ in english .
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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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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 .
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besides octopuses , what other intelligent animals can you name ? how can you tell they are smart ? what attributes do they share with octopuses ?
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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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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 .
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find an example from a novel or short story that reads like poetry . what makes it sound poetic ?
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testing , testing , one , two , three . when your band is trying to perform , feedback is an annoying obstacle , but in the grand orchestra of nature , feedback is not only beneficial , it 's what makes everything work . what exactly is feedback ? the key element , whether in sound , the environment or social science , is a phenomenon called mutual causal interaction , where x affects y , y affects x , and so on , creating an ongoing process called a feedback loop . and the natural world is full of these mechanisms formed by the links between living and nonliving things that build resilience by governing the way populations and food webs respond to events . when plants die , the dead material enriches the soil with humus , a stable mass of organic matter , providing moisture and nutrients for other plants to grow . the more plants grow and die , the more humus is produced , allowing even more plants to grow , and so on . this is an example of positive feedback , an essential force in the buildup of ecosystems . but it 's not called positive feedback because it 's beneficial . rather , it is positive because it amplifies a particular effect or change from previous conditions . these positive , or amplifying , loops can also be harmful , like when removing a forest makes it vulnerable to erosion , which removes organic matter and nutrients from the earth , leaving less plants to anchor the soil , and leading to more erosion . in contrast , negative feedback diminishes or counteracts changes in an ecosystem to maintain a more stable balance . consider predators and their prey . when lynx eat snowshoe hares , they reduce their population , but this drop in the lynx 's food source will soon cause their own population to decline , reducing the predation rate and allowing the hare population to increase again . the ongoing cycle creates an up and down wavelike pattern , maintaining a long-term equilibrium and allowing a food chain to persist over time . feedback processes might seem counterintuitive because many of us are used to more predictable linear scenarios of cause and effect . for instance , it seems simple enough that spraying pesticides would help plants grow by killing pest insects , but it may trigger a host of other unexpected reactions . for example , if spraying pushes down the insect population , its predators will have less food . as their population dips , the reduced predation would allow the insect population to rise , counteracting the effects of our pesticides . note that each feedback is the product of the links in the loop . add one negative link and it will reverse the feedback force entirely , and one weak link will reduce the effect of the entire feedback considerably . lose a link , and the whole loop is broken . but this is only a simple example , since natural communities consist not of separate food chains , but networks of interactions . feedback loops will often be indirect , occurring through longer chains . a food web containing twenty populations can generate thousands of loops of up to twenty links in length . but instead of forming a disordered cacophany , feedback loops in ecological systems play together , creating regular patterns just like multiple instruments , coming together to create a complex but harmonious piece of music . wide-ranging negative feedbacks keep the positive feedbacks in check , like drums maintaining a rhythm . you can look at the way a particular ecosystem functions within its unique habitat as representing its trademark sound . ocean environments dominated by predator-prey interactions , and strong negative and positive loops stabilized by self-damping feedback , are powerful and loud , with many oscillations . desert ecosystems , where the turn over of biomass is slow , and the weak feedbacks loops through dead matter are more like a constant drone . and the tropical rainforest , with its great diversity of species , high nutrient turnover , and strong feedbacks among both living and dead matter , is like a lush panoply of sounds . despite their stabilizing effects , many of these habitats and their ecosystems develop and change over time , as do the harmonies they create . deforestation may turn lush tropics into a barren patch , like a successful ensemble breaking up after losing its star performers . but an abandoned patch of farmland may also become a forest over time , like a garage band growing into a magnificent orchestra .
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but this is only a simple example , since natural communities consist not of separate food chains , but networks of interactions . feedback loops will often be indirect , occurring through longer chains . a food web containing twenty populations can generate thousands of loops of up to twenty links in length . but instead of forming a disordered cacophany , feedback loops in ecological systems play together , creating regular patterns just like multiple instruments , coming together to create a complex but harmonious piece of music .
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how many feedback loops are possible in a food web of 20 species ?
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translator : andrea mcdonough reviewer : jessica ruby hello , humans . my name is matt and for the next several moments , you are going to listen to me . mwah , ha , ha , ha , ha . sorry . i 'm just joking . this is my normal voice . have you ever taken direction from a mysterious voice on the computer before ? no ? perfect ! i want to try an experiment with you , but i ca n't tell you what that experiment entails because if i do , it wo n't work . you 'll just have to trust me . this will all make sense soon , hopefully . if you 're sitting down , stand up from your chair and take a step back . in a moment , i 'm going to have you twirl around , so give yourself a bit of space . need to move some furniture around ? take your time . i 'll wait . on the count of three , you 're going to start hopping on one foot . are you ready ? one , two , three ! hop , hop , hop , hop , hop . nice work ! ok , while you 're still hopping , i now want you to begin barking like a dog . ruff , ruff ; ruff , ruff ; ruff , ruff . wow , that 's quite a bark ! and a few more . ruff , ruff , ruff . and three , two , one , stop ! feel free to relax and sit back down . now , i want you think about how much time passed between the moment i said , `` go ! '' and you began hopping on one foot to the moment i said , `` stop ! '' take a guess . i 'm looking for an exact number of seconds or minutes . now , with a pen and paper , write that number down . all done ? the exact time was actually 26 seconds . did you overestimate ? chances are that you did . so , what was the culprit ? the culprit was time perception . although we can make shockingly precise time estimates , when we experience something new , unusual , or dynamic , like hopping on one foot while taking instructions from a voice on the computer , or , say , jumping out of an airplane , we often miscalculate how much time has passed . meaning , if you bungee jump for the first time , your fall to the bottom may seem like it lasted for 10 seconds while the recorded time may actually show that the jump only lasted for 5 . the reason for this difference is unlike your body 's physical drop to the bottom , your brain 's perception of time does not follow a straight line between two points . some scientists even believe your brain follows more of a curved path that is dependent on the amount of information you take in as you fall downwards . for example , david eagleman , a neuroscientist at baylor college of medicine , believes time perception is heavily influenced by the number of memories and data you record onto your brain . when you have a new experience , like jumping off a high dive for the first time , your senses are heightened . you 're taking in more details about sights , sounds , and smells than you normally would . and you store more data onto your brain in the form of memories . so , the more data you store in your brain , like the smell of chlorine as you leapt from the high dive or the color of the water , the longer your perception of that experience . meaning , the number of memories and data you record on your brain has a direct impact on how long you believe that experience to have lasted . have you ever heard a person recount what it 's like to be in a car accident ? although automotive accidents typically last seconds , those involved often say they felt the accident lasted far longer . time perception can also account for why your childhood may have seem to have lasted forever . by adulthood , a year can slip by in a heartbeat , but children record more data onto their brains . this occurs because many of the experiences we have as children are new and unfamiliar to us . the stack of encoded memories on your brain is so dense that reading them back makes you believe your experiences must have taken forever . additionally , when you 're 5 years old , one year is 1/5 of your life . but , when you 're 25 , one year makes up 1/25 , further altering your perception of time . and , if you 're an adult , think about a trip that you may have taken to a far-away land for the first time . did n't those two weeks you spent exploring your surroundings seem to have lasted far longer than 14 days ? though time perception is rooted in both hard science and theory , it provides a great lesson for us on how to live our lives . i 'm sure you have all heard that a person should n't sit on a couch and let life pass them by . well , time perception tells us why that is . if you get up and engage with the world and have new experiences , and maybe even hop around on one foot and bark like a dog , you will literally perceive your own life to have lasted for a longer period of time .
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so , what was the culprit ? the culprit was time perception . although we can make shockingly precise time estimates , when we experience something new , unusual , or dynamic , like hopping on one foot while taking instructions from a voice on the computer , or , say , jumping out of an airplane , we often miscalculate how much time has passed .
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what kinds of activities tend to slow a person ’ s perception of time ?
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translator : andrea mcdonough reviewer : bedirhan cinar people often think the word `` doubt '' spelling is a little crazy because of the letter `` b '' . since it does n't spell a sound , most folks ca n't figure out what it 's doing there . but in spite of what most of us learn in school , sound is < i > never < /i > the most important aspect of spelling an english word . a word 's meaning and history need to come first . to doubt means to question , to waver , to hesitate . as a noun , it means uncertainty or confusion . the present-day english word `` doubt '' started as a latin word , `` dubitare '' . it first moved from latin into french where it lost both its `` buh '' sound and its letter `` b '' . and then it came into english in the 13th century . about 100 years later , scribes who wrote english but also knew latin , started to reinsert the `` b '' into the word 's spelling , even though no one pronounced it that way . but why would they do this ? why would anyone in their right mind reinsert a silent letter into a spelling ? well , because they knew latin , the scribes understood that the root of `` doubt '' had a `` b '' in it . over time , even as fewer literate people knew latin , the `` b '' was kept because it marked important , meaningful connections to other related words , like `` dubious '' and `` indubitalbly , '' which were subsequently borrowed into english from the same latin root , `` dubitare '' . understanding these historical connections not only helped us to spell `` doubt , '' but also to understand the meaning of these more sophisticated words . but the story does n't end there . if we look even deeper , we can see beyond the shadow of a doubt , just how revealing that `` b '' can be . there are only two base words in all of english that have the letters `` d-o-u-b '' : one is doubt , and the other is double . we can build lots of other words on each of these bases , like doubtful and doubtless , or doublet , and redouble , and doubloon . it turns out that if we look into their history , we can see that they both derive from the same latin forms . the meaning of double , two , is reflected in a deep understanding of doubt . see , when we doubt , when we hesitate , we second guess ourselves . when we have doubts about something , when we have questions or confusion , we are of two minds . historically , before english began to borrow words from french , it already had a word for doubt . that old english word was `` tweogan , '' a word whose relationship to `` two '' is clear in its spelling as well . so the next time you are in doubt about why english spelling works the way it does , take a second look . what you find just might make you do a double-take .
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but in spite of what most of us learn in school , sound is < i > never < /i > the most important aspect of spelling an english word . a word 's meaning and history need to come first . to doubt means to question , to waver , to hesitate .
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what is a word that you commonly misspell ? explain the meaning and history of the word . does this help you understand how it should be spelled ?
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translator : jessica ruby reviewer : brian greene could human civilization eventually spread across the whole milky way galaxy ? could we move beyond our small blue planet to establish colonies in the multitude of star systems out there ? this question 's a pretty daunting one . there are around 300 billion stars in the galaxy , which is about 160,000 light-years across . so far we 've sent a single spacecraft outside our solar system , trudging along at 0.006 % of the speed of light . at that rate , it would take over 2.5 billion years just to get from one end of the galaxy to the other . and then there 's the question of human survival . the gulf between stars is simply enormous . we could n't live sustainably on most planets , and we require a lot of resources to stay alive . and yet , decades ago , scholars found that it 's theoretically possible to not just spread human civilization across the galaxy , but to do so quite quickly , without breaking any known laws of physics . their idea is based on the work of a mathematician named john von neumann , who designed on paper machines that could self-replicate and create new generations of themselves . these would later come to be known as von neumann machines . in the context of space exploration , von neumann machines could be built on earth and launched into space . there , the self-sufficient machines would land on distant planets . they would then mine the available resources and harvest energy , build replicas of themselves , launch those to the nearest planets , and continue the cycle . the result is the creation of millions of probes spreading outwards into the universe like a drop of ink in a fishbowl . scholars crunched the numbers and found that a single von neumann machine traveling at 5 % of the speed of light should be able to replicate throughout our galaxy in 4 million years or less . that may sound like a long time , but when you consider that our universe is 14 billion years old , on a cosmic scale , it 's incredibly fast - the equivalent of about 2.5 hours in an entire year . creating von neumann machines would require a few technologies we do n't have yet , including advanced artificial intelligence , miniaturization , and better propulsion systems . if we wanted to use them to spread actual humans throughout the galaxy , we would need yet another technological leap - the ability to artificially grow biological organisms and bodies using raw elements and genetic information . regardless , if in the last billion years an alien civilization created such a machine and set it multiplying its way toward us , our galaxy would be swarming with them by now . so then where are all these machines ? some astronomers , like carl sagan , say that intelligent aliens would n't build self-replicating machines at all . they might hurtle out of control , scavenging planets to their cores in order to keep replicating . others take the machines absence as proof that intelligent alien civilizations do n't exist , or that they go extinct before they can develop the necessary technologies . but all this has n't stopped people from imagining what it would be like if they were out there . science fiction author david brin writes about a universe in which many different von neumann machines exist and proliferate simultaneously . some are designed to greet young civilizations , others to locate and destroy them before they become a threat . in fact , in brin 's story `` lungfish , '' some von neumann machines are keeping a close watch over the earth right now , waiting for us to reach a certain level of sophistication before they make their move . for now , all we have is curiosity and theory . but the next time you look at the night sky , consider that billions of self-replicating machines could be advancing between stars in our galaxy right now . if they exist , one of them will eventually land on earth , or maybe , just maybe , they 're already here .
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their idea is based on the work of a mathematician named john von neumann , who designed on paper machines that could self-replicate and create new generations of themselves . these would later come to be known as von neumann machines . in the context of space exploration , von neumann machines could be built on earth and launched into space . there , the self-sufficient machines would land on distant planets .
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what are von neumann machines ?
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mysteries of vernacular : yankee , a new england resident or , more generally , a person who lives in or is from the united states . though the origin of yankee is uncertain , this all-american word most likely descended from the dutch moniker janke , a diminutive meaning little jan , or little john . in the 17th century , janke was the common nickname of dutch sailors , pirates in particular . a dutch pirate ship operating in the west indies was even called the yankee . over the years , yankee transformed from a pirate 's nickname into a general term of contempt . in 1758 , british general james wolfe used yankee as a pejorative term for the colonists under his supervision . but the insult was n't limited to soldiers . yankee quickly came to mean new englander , and by the 1780s , it was used to look down upon any american . during the revolution , colonists co-opted yankee and transformed it into a mark of national honor . the civil war , however , intensified the derisive definition when it was used by southerners to mock members of the union . today , it carries much less emotion , unless , of course , we 're talking about baseball .
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yankee quickly came to mean new englander , and by the 1780s , it was used to look down upon any american . during the revolution , colonists co-opted yankee and transformed it into a mark of national honor . the civil war , however , intensified the derisive definition when it was used by southerners to mock members of the union .
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why do you think the colonists transformed yankee from an insult into a source of pride ?
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are you as good at things as you think you are ? how good are you at managing money ? what about reading people 's emotions ? how healthy are you compared to other people you know ? are you better than average at grammar ? knowing how competent we are and how are skill stack up against other people 's is more than a self-esteem boost . it helps us figure out when we can forge ahead on our own decisions and instincts and when we need , instead , to seek out advice . but psychological research suggests that we 're not very good at evaluating ourselves accurately . in fact , we frequently overestimate our own abilities . researchers have a name for this phenomena , the dunning-kruger effect . this effect explains why more than 100 studies have shown that people display illusory superiority . we judge ourselves as better than others to a degree that violates the laws of math . when software engineers at two companies were asked to rate their performance , 32 % of the engineers at one company and 42 % at the other put themselves in the top 5 % . in another study , 88 % of american drivers described themselves as having above average driving skills . these are n't isolated findings . on average , people tend to rate themselves better than most in disciplines ranging from health , leadership skills , ethics , and beyond . what 's particularly interesting is that those with the least ability are often the most likely to overrate their skills to the greatest extent . people measurably poor at logical reasoning , grammar , financial knowledge , math , emotional intelligence , running medical lab tests , and chess all tend to rate their expertise almost as favorably as actual experts do . so who 's most vulnerable to this delusion ? sadly , all of us because we all have pockets of incompetence we do n't recognize . but why ? when psychologists dunning and kruger first described the effect in 1999 , they argued that people lacking knowledge and skill in particular areas suffer a double curse . first , they make mistakes and reach poor decisions . but second , those same knowledge gaps also prevent them from catching their errors . in other words , poor performers lack the very expertise needed to recognize how badly they 're doing . for example , when the researchers studied participants in a college debate tournament , the bottom 25 % of teams in preliminary rounds lost nearly four out of every five matches . but they thought they were winning almost 60 % . without a strong grasp of the rules of debate , the students simply could n't recognize when or how often their arguments broke down . the dunning-kruger effect is n't a question of ego blinding us to our weaknesses . people usually do admit their deficits once they can spot them . in one study , students who had initially done badly on a logic quiz and then took a mini course on logic were quite willing to label their original performances as awful . that may be why people with a moderate amount of experience or expertise often have less confidence in their abilities . they know enough to know that there 's a lot they do n't know . meanwhile , experts tend to be aware of just how knowledgeable they are . but they often make a different mistake : they assume that everyone else is knowledgeable , too . the result is that people , whether they 're inept or highly skilled , are often caught in a bubble of inaccurate self-perception . when they 're unskilled , they ca n't see their own faults . when they 're exceptionally competent , they do n't perceive how unusual their abilities are . so if the dunning-kruger effect is invisible to those experiencing it , what can you do to find out how good you actually are at various things ? first , ask for feedback from other people , and consider it , even if it 's hard to hear . second , and more important , keep learning . the more knowledgeable we become , the less likely we are to have invisible holes in our competence . perhaps it all boils down to that old proverb : when arguing with a fool , first make sure the other person is n't doing the same thing .
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but why ? when psychologists dunning and kruger first described the effect in 1999 , they argued that people lacking knowledge and skill in particular areas suffer a double curse . first , they make mistakes and reach poor decisions .
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are there areas where people are more reliably successful in identifying their shortcomings ? what distinguishes these areas from areas where people can ’ t recognize their shortcomings ?
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take a moment to think about the us constitution . what 's the first thing that comes to mind ? freedom of speech ? protection from illegal searches ? the right to keep and bear arms ? these passages are cited so often that we can hardly imagine the document without them , but that 's exactly what the writers of the constitution did . the list of individual freedoms known as the bill of rights was not in the original text and was n't added for another three years . so does this mean the founders did n't consider them ? the answer goes back to the very origins of the constitution itself . even prior to the first shots of the american revolution , the thirteen colonies worked together through a provisional government called the continental congress . during the war in 1781 , the articles of confederation were ratified as the first truly national government . but establishing a new nation would prove easier than running it . congress had no power to make the states comply with their laws . when the national government proved unable to raise funds , enforce foreign treaties , or suppress rebellions , it was clear reform was needed . so in may 1787 , all the states but rhode island sent delegates to philidelphia for a constitutional convention . a majority of these delegates favored introducing a new national constitution to create a stronger federal government . thanks to compromises on issues like state representation , taxation power , and how to elect the president , their proposal gradually gained support . but the final text drafted in september still had to be approved by conventions held in the states . so over the next few months , ratification would be debated across the young nation . among those who championed the new document were leading statesmen alexander hamilton , james madison , and john jay . together , they laid out eloquent philosophical arguments for their positions in a series of 85 essays now known as the federalist papers . but others felt the constitution was overreaching and that more centralized authority would return the states to the sort of tyranny they had just escaped . these anti-federalists were especially worried by the text 's apparent lack of protections for individual liberties . as the conventions proceeded , many of these critics shifted from opposing the constitution entirely to insisting on adding an explicit declaration of rights . so what was the federalists problem with this idea ? while their opponents accused them of despotism , wanting to maintain absolute power in the central government , their real motives were mostly practical . changing the constitution when it had already been ratified by some states could complicate the entire process . more importantly , madison felt that people 's rights were already guaranteed through the democratic process , while adding extra provisions risked misinterpretation . and some feared that creating an explicit list of things the government ca n't do would imply that it can do everything else . after the first five states ratified the constitution quickly , the debate grew more intense . massachusetts and several other states would only ratify if they could propose their own amendments for consideration . leading federalists recognized the need to compromise and promised to give them due regard . once ratification by nine states finally brought the constitution into legal force , they made good on their promise . during a meeting of the first united states congress , representative james madison stood on the house floor to propose the very amendments he had previously believed to be unnecessary . after much debate and revision , first in the congress , and then in the states , ten amendments were ratified on december 15 , 1791 , over three years after the us constitution had become law . today , every sentence , word , and punctuation mark in the bill of rights is still considered fundamental to the freedoms americans enjoy , even though the original framers left them out .
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even prior to the first shots of the american revolution , the thirteen colonies worked together through a provisional government called the continental congress . during the war in 1781 , the articles of confederation were ratified as the first truly national government . but establishing a new nation would prove easier than running it .
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the ______ was the first national government before the u.s. constitution .
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translator : andrea mcdonough reviewer : bedirhan cinar have you heard the one about thomas jefferson and the louisiana territory ? thomas jefferson , author of the declaration of independence , was not a fan of the new constitution presented in 1787 . he was very worried that the constitution gave too much power to the new , national government , and not enough power to the states , an issue known as `` big government '' . jefferson only reluctantly agreed to support it when his friend , james madison , promised to propose a bill of rights after it was ratified . but jefferson 's fears about big government did not go away . for example , secretary of the treasury , alexander hamilton , proposed a national bank in 1790 , and jefferson knew there was no provision in the constitution to permit such a thing . hamilton claimed some sort of implied powers mumbo-jumbo . sure , it was n't written in the constitution , but the constitution implied that it could be done . but , jefferson was n't buying it . nonetheless , the bank was established by hamilton and president washington . when jefferson was sworn in as president in 1801 , he pledged to reduce the size and scope of the national government . but , of course , things did n't go exactly as he had planned . spain secretly transferred the louisiana territory to france right beneath jefferson 's nose . when congress found out , they quickly began discussions with france to buy a piece of the territory along the mississippi river for about $ 2 million . but , there was one little problem : jefferson knew there was no provision in the constitution to buy foreign territory . so what was a strict constructionist to do ? first , he tried to get an amendment to the constitution passed that would expressly permit the purchase , but congress was n't willing to do it . then , without permission , the u.s. negotiators in france cut a deal for all of the territory for a cool $ 15 million dollars . that new land doubled the size of the nation ! now jefferson was really stuck . he knew that the territory would be a great acquisition for the country , providing lots of new land for farmers and other settlers , but how could he constitutionally justify it ? in the end , jefferson turned to the argument used by his old foe alexander hamilton . he claimed that the power to purchase the territory is implied in the constitution 's treaty-making power . this was the exact argument that he had mocked openly a decade before , so it must have crushed his pride to have to use it . but more importantly , he may have committed the biggest big government play ever ! how ironic is it that one of the biggest opponents of big government doubled the size of the young country and did so while openly questioning its constitutionality ? at $ 15 million , which is about three cents an acre , it has been called by many the greatest real estate deal in the history of the united states .
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translator : andrea mcdonough reviewer : bedirhan cinar have you heard the one about thomas jefferson and the louisiana territory ? thomas jefferson , author of the declaration of independence , was not a fan of the new constitution presented in 1787 . he was very worried that the constitution gave too much power to the new , national government , and not enough power to the states , an issue known as `` big government '' .
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thomas jefferson ultimately justified the louisiana purchase as being implied in the constitution ’ s
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light : it 's the fastest thing in the universe , but we can still measure its speed if we slow down the animation , we can analyze light 's motion using a space-time diagram , which takes a flipbook of animation panels , and turns them on their side . in this lesson , we 'll add the single experimental fact that whenever anyone measures just how fast light moves , they get the same answer : 299,792,458 meters every second , which means that when we draw light on our space-time diagram , it 's world line always has to appear at the same angle . but we saw previously that speed , or equivalently world line angles , change when we look at things from other people 's perspective . to explore this contradiction , let 's see what happens if i start moving while i stand still and shine the laser at tom . first , we 'll need to construct the space-time diagram . yes , that means taking all of the different panels showing the different moments in time and stacking them up . from the side , we see the world line of the laser light at its correct fixed angle , just as before . so far , so good . but that space-time diagram represents andrew 's perspective . what does it look like to me ? in the last lesson , we showed how to get tom 's perspective moving all the panels along a bit until his world line is completely vertical . but look carefully at the light world line . the rearrangement of the panels means it 's now tilted over too far . i 'd measure light traveling faster than andrew would . but every experiment we 've ever done , and we 've tried very hard , says that everyone measures light to have a fixed speed . so let 's start again . in the 1900s , a clever chap named albert einstein worked out how to see things properly , from tom 's point of view , while still getting the speed of light right . first , we need to glue together the separate panels into one solid block . this gives us our space-time , turning space and time into one smooth , continuous material . and now , here is the trick . what you do is stretch your block of space-time along the light world line , then squash it by the same amount , but at right angles to the light world line , and abracadabra ! tom 's world line has gone vertical , so this does represent the world from his point of view , but most importantly , the light world line has never changed its angle , and so light will be measured by tom going at the correct speed . this superb trick is known as a lorentz transformation . yeah , more than a trick . slice up the space-time into new panels and you have the physically correct animation . i 'm stationary in the car , everything else is coming past me and the speed of light works out to be that same fixed value that we know everyone measures . on the other hand , something strange has happened . the fence posts are n't spaced a meter apart anymore , and my mom will be worried that i look a bit thin . but that 's not fair . why do n't i get to look thin ? i thought physics was supposed to be the same for everyone . yes , no , it is , and you do . all that stretching and squashing of space-time has just muddled together what we used to think of separately as space and time . this particular squashing effect is known as lorentz contraction . okay , but i still do n't look thin . no , yes , you do . now that we know better about space-time , we should redraw what the scene looked like to me . to you , i appear lorentz contracted . oh but to you , i appear lorentz contracted . yes . uh , well , at least it 's fair . and speaking of fairness , just as space gets muddled with time , time also gets muddled with space , in an effect known as time dilation . no , at everyday speeds , such as tom 's car reaches , actually all the effects are much , much smaller than we 've illustrated them . oh , yet , careful experiments , for instance watching the behavior of tiny particles whizzing around the large hadron collider confirmed that the effects are real . and now that space-time is an experimentally confirmed part of reality , we can get a bit more ambitious . what if we were to start playing with the material of space-time itself ? we 'll find out all about that in the next animation .
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so far , so good . but that space-time diagram represents andrew 's perspective . what does it look like to me ?
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why do we have to redraw the animation as seen from andrew 's perspective ?
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you can think of your cells as the kitchen in a busy restaurant . sometimes your body orders chicken . other times , it orders steak . your cells have to be able to crank out whatever the body needs and quickly . when an order comes in , the chef looks to the cookbook , your dna , for the recipe . she then transcribes that message onto a piece of paper called rna and brings it back to her countertop , the ribosome . there , she can translate the recipe into a meal , or for your cells , a protein , by following the directions that she 's copied down . but rna does more for the cell than just act as a messenger between a cook and her cookbook . it can move in reverse and create dna , it can direct amino acids to their targets , or it can take part in rna interference , or rnai . but wait ! why would rna want to interfere with itself ? well , sometimes a cell does n't want to turn all of the messenger rna it creates into protein , or it may need to destroy rna injected into the cell by an attacking virus . say , for example , in our cellular kitchen , that someone wanted to cancel their order or decided they wanted chips instead of fries . that 's where rnai comes in . thankfully , your cells have the perfect knives for just this kind of job . when the cell finds or produces long , double-stranded rna molecules , it chops these molecules up with a protein actually named dicer . now , these short snippets of rna are floating around in the cell , and they 're picked up by something called risc , the rna silencing complex . it 's composed of a few different proteins , the most important being slicer . this is another aptly named protein , and we 'll get to why in just a second . risc strips these small chunks of double-stranded rna in half , using the single strand to target matching mrna , looking for pieces that fit together like two halves of a sandwich . when it finds the matching piece of mrna , risc 's slicer protein slices it up . the cell then realizes there are odd , strangely sized pieces of rna floating around and destroys them , preventing the mrna from being turned into protein . so , you have double-stranded rna , you dice it up , it targets mrna , and then that gets sliced up , too . voila ! you 've prevented expression and saved yourself some unhappy diners . so , how did anybody ever figure this out ? well , the process was first discovered in petunias when botanists trying to create deep purple blooms introduced a pigment-producing gene into the flowers . but instead of darker flowers , they found flowers with white patches and no pigment at all . instead of using the rna produced by the new gene to create more pigment , the flowers were actually using it to knock down the pigment-producing pathway , destroying rna from the plant 's original genes with rnai , and leaving them with pigment-free white flowers . scientists saw a similar phenomena in tiny worms called c. elegans , and once they figured out what was happening , they realized they could use rnai to their advantage . want to see what happens when a certain gene is knocked out of a worm or a fly ? introduce an rnai construct for that gene , and bam ! no more protein expression . you can even get creative and target that effect to certain systems , knocking down genes in just the brain , or just the liver , or just the heart . figuring out what happens when you knock down a gene in a certain system can be an important step in figuring out what that gene does . but rnai is n't just for understanding how things happen . it can also be a powerful , therapeutic tool and could be a way for us to manipulate what is happening within own cells . researchers have been experimenting with using it to their advantage in medicine , including targeting rna and tumor cells in the hopes of turning off cancer-causing genes . in theory , our cellular kitchens could serve up an order of cells , hold the cancer .
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introduce an rnai construct for that gene , and bam ! no more protein expression . you can even get creative and target that effect to certain systems , knocking down genes in just the brain , or just the liver , or just the heart .
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which nucleic acid acts as a messenger between dna and protein ?
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hello , everyone . let 's begin our guided tour . welcome to the museum of museums . museums have been a part of human history for over 2000 years . but they were n't always like the ones we visit today . the history of museums is far older and much stranger than you might imagine . we 'll start over here in the greek wing . our word museum comes from the greek mouseion , temples built for the muses , the goddesses of the arts and the sciences . supplicants asked the muses to keep watch over academics and grant ingenuity to those they deemed worthy . the temples were filled with offerings of sculptures , mosaics , complex scientific apparatuses , poetic and literary inscriptions , and any other tribute that would demonstrate a mortal 's worthiness for divine inspiration . we have arrived at the mesopotamian wing . the first museum was created in 530 b.c . in what is now iraq . and the first curator was actually a princess . ennigaldi-nanna started to collect and house mesopotamian antiquities in e-gig-par , her house . when archeologists excavated the area , they discovered dozens of artifacts neatly arranged in rows , with clay labels written in three languages . she must have had interesting parties . the tradition of collecting and displaying intriguing items began to be mimicked , as you can see here in the roman empire wing . treasure houses of politicians and generals were filled with the spoils of war , and royal menageries displayed exotic animals to the public on special occasions , like gladiator tournaments . as you can see , we have a lion here and a gladiator , and , well , the janitor ought to be in this wing clearly . moving on , hurry along . the next step in the evolution of museums occurred in the renaissance , when the study of the natural world was once again encouraged after almost a millennium of western ignorance . curiosity cabinets , also referred to as wunderkammers , were collections of objects that acted as a kind of physical encyclopedia , showcasing artifacts . just step into the wardrobe here . there you go . mind the coats . and we 'll tour ole worm 's cabinet , one of the most notable wunderkammers belonged to a wealthy 17th-century naturalist , antiquarian , and physician ole worm . ole worm collected natural specimens , human skeletons , ancient runic texts , and artifacts from the new world . in other curiosity cabinets , you could find genetic anomalies , precious stones , works of art , and religious and historic relics . oh my . you might not want to touch that . these cabinets were private , again , often in residencies , curated by their owners , rulers and aristocrats , as well as merchants and early scientists . now , who hears a circus organ ? in the 1840s , an enterprising young showman named phineas t. barnum purchased some of the more famous cabinets of curiosity from europe and started barnum 's american museum in new york city . a spectacular hodgepodge of zoo , lecture hall , wax museum , theater , and freak show that was known for its eclectic residents , such as bears , elephants , acrobats , giants , siamese twins , a fiji mermaid , and a bearded lady , along with a host of modern machinery and scientific instruments . museums open to the public are a relatively new phenomenon . before barnum , the first public museums were only accessible by the upper and middle classes , and only on certain days . visitors would have to apply to visit the museum in writing prior to admision , and only small groups could visit the museum each day . the louvre famously allowed all members of the public into the museum but only three days a week . in the 19th century , the museum as we know it began to take shape . institutions like the smithsonian were started so that objects could be seen and studied , not just locked away . american museums , in particular , commissioned experiments and hired explorers to seek out and retrieve natural samples . museums became centers for scholarship and artistic and scientific discovery . this is often called the museum age . nowadays , museums are open to everybody , are centers of learning and research , and are turning into more hands-on institutions . but the question of who gets to go is still relevant as ticket prices can sometimes bar admission to those future scholars , artists and targets of divine inspiration who ca n't afford to satisfy their curiosity . thank you all for coming , and please , feel free to stop by the gift shop of gift shops on your way out .
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let 's begin our guided tour . welcome to the museum of museums . museums have been a part of human history for over 2000 years .
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how were the greek museums similar to our current museums ? how were they different ?
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what happens after death ? is there a restful paradise ? an eternal torment ? a rebirth ? or maybe just nothingness ? well , one chinese emperor thought that whatever the hereafter was , he better bring an army . we know that because in 1974 , farmers digging a well near their small village stumbled upon one of the most important finds in archeological history : vast underground chambers surrounding that emperor 's tomb , and containing more than 8,000 life-size clay soldiers ready for battle . the story of the subterranean army begins with ying zheng , who came to power as the king of the qin state at the age of 13 in 246 bce . ambitious and ruthless , he would go on to become qin shi huangdi , the first emperor of china after uniting its seven warring kingdoms . his 36 year reign saw many historic accomplishments , including a universal system of weights and measures , a single standardized writing script for all of china , and a defensive barrier that would later come to be known as the great wall . but perhaps qin shi huangdi dedicated so much effort to securing his historical legacy because he was obsessed with his mortality . he spent his last years desperately employing alchemists and deploying expeditions in search of elixirs of life that would help him achieve immortality . and as early as the first year of his reign , he began the construction of a massive underground necropolis filled with monuments , artifacts , and an army to accompany him into the next world and continue his rule . this magnificent army is still standing in precise battle formation and is split across several pits . one contains a main force of 6,000 soldiers , each weighing several hundred pounds , a second has more than 130 war chariots and over 600 horses , and a third houses the high command . an empty fourth pit suggests that the grand project could not be finished before the emperor 's death . in addition , nearby chambers contain figures of musicians and acrobats , workers and government officials , and various exotic animals , indicating that emperor qin had more plans for the afterlife than simply waging war . all the figurines are sculpted from terracotta , or baked earth , a type of reddish brown clay . to construct them , multiple workshops and reportedly over 720,000 laborers were commandeered by the emperor , including groups of artisans who molded each body part separately to construct statues as individual as the real warriors in the emperor 's army . they stand according to rank and feature different weapons and uniforms , distinct hairstyles and expressions , and even unique ears . originally , each warrior was painted in bright colors , but their exposure to air caused the paint to dry and flake , leaving only the terracotta base . it is for this very reason that another chamber less than a mile away has not been excavated . this is the actual tomb of qin shi huangdi , reported to contain palaces , precious stones and artifacts , and even rivers of mercury flowing through mountains of bronze . but until a way can be found to expose it without damaging the treasures inside , the tomb remains sealed . emperor qin was not alone in wanting company for his final destination . ancient egyptian tombs contain clay models representing the ideal afterlife , the dead of japan 's kofun period were buried with sculptures of horses and houses , and the graves of the jaina island off the mexican coast are full of ceramic figurines . fortunately , as ruthless as he was , emperor qin chose to have servants and soldiers built for this purpose , rather than sacrificing living ones to accompany him , as had been practiced in egypt , west africa , anatolia , parts of north america and even china during the previous shang and zhou dynasties . and today , people travel from all over the world to see these stoic soldiers silently awaiting their battle orders for centuries to come .
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in addition , nearby chambers contain figures of musicians and acrobats , workers and government officials , and various exotic animals , indicating that emperor qin had more plans for the afterlife than simply waging war . all the figurines are sculpted from terracotta , or baked earth , a type of reddish brown clay . to construct them , multiple workshops and reportedly over 720,000 laborers were commandeered by the emperor , including groups of artisans who molded each body part separately to construct statues as individual as the real warriors in the emperor 's army .
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___________ commissioned the building of the terracotta warriors ?
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would mathematics exist if people did n't ? since ancient times , mankind has hotly debated whether mathematics was discovered or invented . did we create mathematical concepts to help us understand the universe around us , or is math the native language of the universe itself , existing whether we find its truths or not ? are numbers , polygons and equations truly real , or merely ethereal representations of some theoretical ideal ? the independent reality of math has some ancient advocates . the pythagoreans of 5th century greece believed numbers were both living entities and universal principles . they called the number one , `` the monad , '' the generator of all other numbers and source of all creation . numbers were active agents in nature . plato argued mathematical concepts were concrete and as real as the universe itself , regardless of our knowledge of them . euclid , the father of geometry , believed nature itself was the physical manifestation of mathematical laws . others argue that while numbers may or may not exist physically , mathematical statements definitely do n't . their truth values are based on rules that humans created . mathematics is thus an invented logic exercise , with no existence outside mankind 's conscious thought , a language of abstract relationships based on patterns discerned by brains , built to use those patterns to invent useful but artificial order from chaos . one proponent of this sort of idea was leopold kronecker , a professor of mathematics in 19th century germany . his belief is summed up in his famous statement : `` god created the natural numbers , all else is the work of man . '' during mathematician david hilbert 's lifetime , there was a push to establish mathematics as a logical construct . hilbert attempted to axiomatize all of mathematics , as euclid had done with geometry . he and others who attempted this saw mathematics as a deeply philosophical game but a game nonetheless . henri poincaré , one of the father 's of non-euclidean geometry , believed that the existence of non-euclidean geometry , dealing with the non-flat surfaces of hyperbolic and elliptical curvatures , proved that euclidean geometry , the long standing geometry of flat surfaces , was not a universal truth , but rather one outcome of using one particular set of game rules . but in 1960 , nobel physics laureate eugene wigner coined the phrase , `` the unreasonable effectiveness of mathematics , '' pushing strongly for the idea that mathematics is real and discovered by people . wigner pointed out that many purely mathematical theories developed in a vacuum , often with no view towards describing any physical phenomena , have proven decades or even centuries later , to be the framework necessary to explain how the universe has been working all along . for instance , the number theory of british mathematician gottfried hardy , who had boasted that none of his work would ever be found useful in describing any phenomena in the real world , helped establish cryptography . another piece of his purely theoretical work became known as the hardy-weinberg law in genetics , and won a nobel prize . and fibonacci stumbled upon his famous sequence while looking at the growth of an idealized rabbit population . mankind later found the sequence everywhere in nature , from sunflower seeds and flower petal arrangements , to the structure of a pineapple , even the branching of bronchi in the lungs . or there 's the non-euclidean work of bernhard riemann in the 1850s , which einstein used in the model for general relativity a century later . here 's an even bigger jump : mathematical knot theory , first developed around 1771 to describe the geometry of position , was used in the late 20th century to explain how dna unravels itself during the replication process . it may even provide key explanations for string theory . some of the most influential mathematicians and scientists of all of human history have chimed in on the issue as well , often in surprising ways . so , is mathematics an invention or a discovery ? artificial construct or universal truth ? human product or natural , possibly divine , creation ? these questions are so deep the debate often becomes spiritual in nature . the answer might depend on the specific concept being looked at , but it can all feel like a distorted zen koan . if there 's a number of trees in a forest , but no one 's there to count them , does that number exist ?
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so , is mathematics an invention or a discovery ? artificial construct or universal truth ? human product or natural , possibly divine , creation ?
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name at least one mathematical idea or principle that you feel is a universal truth . support your choice .
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translator : tom carter reviewer : bedirhan cinar carbon dioxide , or co2 , is the main greenhouse gas in climate change . so how does co2 get into our atmosphere ? well , carbon is part of a cycle . it starts with the sun , which heats the earth 's surface with more energy in one hour than the whole world uses in a year . plants , which are kind of like biological chefs , take that sunlight , and then suck in some co2 from the air , mix them together , and bam ! they create a stored form of energy , in the form of carbohydrates such as glucose and sucrose . the process is called photosynthesis . when animals like us eat those plants our stomachs convert that food back into energy for our own growth . greenhouse gases are a byproduct of this process , and are released through waste . if those plants die , they decompose , and tiny microorganisms break down those carbohydrates and again , release greenhouse gases as a byproduct . as you see , energy originates from the sun . it is then transferred as it moves through the food chain . but sometimes , carbon based organisms like plants or animals get stuck in the earth . when this happens , they 're compressed under tons of pressure , and turned into carbon-based fossil fuels like oil , coal or natural gas . since the industrial revolution , humans have been pulling those fossil fuels out of the ground and burning them , activating the stored energy to make electricity and power engines . but the thing is it also releases millions of years worth of stored co2 back into the air . in addition , humans breathe in oxygen and breathe out co2 . but plants do the opposite . trees suck up huge amounts of co2 , which balances the cycle . thus , deforestation reduces the plants that store co2 . we 're attacking the cycle from both sides . think of it like a computer . a computer can operate a few programs at a time , right ? normally , when you 've finished with a document , you save , and you close it , so as not to overwork the computer . then , imagine you stopped closing your documents . so they were all open at once . your computer would n't be able to process it all . it would start to slow down , and then to freeze , and eventually it would crash . which might be where our environment is heading if we keep overloading the carbon cycle . so is there any way to rebalance the ecosystem ? what about technology ? technology is defined as a technique to solve a problem . and so , sustainable technologies are those whose output is equal to their input . they do not create negative externalities , such as co2 , in the present or the future . they sort of cancel themselves out to solve the problem . to achieve this , we need to invent sustainable technologies . if we put all the ideas and technologies ever created into one circle , then invention is the pushing of the boundaries of that circle . and the area outside of the circle is infinite , meaning the potential for invention is limitless . think about some of the incredible clean technologies we have today . [ wind ; electric & amp ; amp ; solar cars ; biogas ] [ biofuels ; photosynthetic algae ; compost ] all those ideas have one thing in common . they all came from people . people innovate . people create . it 's the limitless potential of creative people to build unimagined technologies that is going to stop climate change and rebalance the ecosystem . and that is something to be hopeful about .
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they create a stored form of energy , in the form of carbohydrates such as glucose and sucrose . the process is called photosynthesis . when animals like us eat those plants our stomachs convert that food back into energy for our own growth .
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the process of plants turning sunlight and carbon into sucrose and glucose is called :
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in ancient greece , violent internal conflict between bordering neighbors and war with foreign invaders was a way of life , and greeks were considered premier warriors . most greek city-states surrounded themselves with massive defensive walls for added protection . sparta in its prime was a different story , finding walls unnecessary when it had an army of the most feared warriors in the ancient world . so what was sparta doing differently than everyone else to produce such fierce soldiers ? to answer that question , we turn to the written accounts of that time . there are no surviving written accounts from spartans themselves , as it was forbidden for spartans to keep records , so we have to rely on those of non-spartan ancient historians , like herodotus , thucydides , and plutarch . these stories may be embellished and depict sparta at the apex of its power , so take them with a grain of salt . for spartans , the purpose for their existence was simple : to serve sparta . on the day of their birth , elder spartan leaders examined every newborn . the strong healthy babies were considered capable of fulfilling this purpose , and the others may have been left on mount taygetus to die . every spartan , boy or girl , was expected to be physically strong , mentally sharp , and emotionally resilient . and it was their absolute duty to defend and promote sparta at all costs . so in the first years of their lives , children were raised to understand that their loyalty belonged first to sparta , and then to family . this mindset probably made it easier for the spartan boys , who upon turning seven , were sent to the agoge , a place with one main purpose : to turn a boy into a spartan warrior through thirteen years of relentless , harsh , and often brutal training . the spartans prized physical perfection above all else , and so the students spent a great deal of their time learning how to fight . to ensure resilience in battle , boys were encouraged to fight among themselves , and bullying , unlike today , was acceptable . in order to better prepare the boys for the conditions of war , the boys were poorly fed , sometimes even going days without eating . they also were given little in the way of clothing so that they could learn to deal with different temperatures . spartan boys were encouraged to steal in order to survive , but if they were caught , they would be disciplined , not because they stole , but because they were caught in the act . during the annual contest of endurance in a religious ritual known as the diamastigosis , teenage boys were whipped in front of an altar at the sanctuary of artemis orthia . it was common for boys to die on the altar of the goddess . fortunately , not everything was as brutal as that . young spartans were also taught how to read , write , and dance , which taught them graceful control of their movements and helped them in combat . while the responsibilities for the girls of sparta were different , the high standards of excellence and expectation to serve sparta with their lives remained the same . spartan girls lived at home with their mothers as they attended school . their curriculum included the arts , music , dance , reading , and writing . and to stay in peak physical condition , they learned a variety of sports , such as discus , javelin , and horseback riding . in sparta , it was believed that only strong and capable women could bear children that would one day become strong and capable warriors . to all spartans , men and women , perhaps the most important lesson from spartan school was allegiance to sparta . to die for their city-state was seen as the completion of one 's duty to sparta . upon their death , only men who died in battle and women who died in childbirth were given tombstones . in the eyes of their countrymen , both died so that sparta could live .
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this mindset probably made it easier for the spartan boys , who upon turning seven , were sent to the agoge , a place with one main purpose : to turn a boy into a spartan warrior through thirteen years of relentless , harsh , and often brutal training . the spartans prized physical perfection above all else , and so the students spent a great deal of their time learning how to fight . to ensure resilience in battle , boys were encouraged to fight among themselves , and bullying , unlike today , was acceptable .
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the spartans prized physical perfection above all else . which of the following did teachers at the agoge not encourage ?
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( music ) quick ! what 's common between beef burgers , baseball training and auto mufflers ? tough question . let 's ask it another way . what 's the common factor between mcdonald 's , d-bat and meineke ? you may know the answer if , along with a big mac , you 've absorbed a fragment of the romantic story of ray kroc . he 's the salesman that created what became the world 's biggest fast food chain . he did it by making a deal with a couple of men called the mcdonalds . brothers they were , owners of a small restaurant chain , and the deal was , he could use their brand name and their methods . then he invited small entrepreneurs to open mcdonald 's , that they 'd run as operators , with an ownership state . very different than the business model where mom and pop stores have full ownership , but no similar support . all the examples in my opening question are a franchise operation . kroc is sometimes credited with inventing franchising , and so is isaac singer , the sewing machine magnate . not so . the real genesis of franchising was not in stitches or beef , it was in beauty . martha matilda harper was a canadian-born maid . she made the beds , cleaned house , did the shopping . in the employment of a doctor 's family in ontario , she acquired a secret formula for shampoo , one more scientifically based than the quackeries advertized every day in the newspapers . the kindly doctor also taught the maturing young woman the elements of physiology . martha had a secret ambition to go along with the secret formula : a determination to run her own business . by 1888 , serving as a maid in rochester , new york , she saved enough money -- 360 dollars -- to think of opening a public hairdressing salon . but before she could realize her dream , two blows fell . she became sick , and collapsed from exhaustion . mrs. helen smith , a healing practitioner of the christian science faith , was summoned to her bedside . the two women prayed , and martha recovered . no sooner was she better then she was told , `` oh no , you ca n't rent the place you 've eyed . '' you see , her venture was to be the first public hairdressing salon . a woman in business was shocking enough then . only 17 percent of the workforce in 1890 was female , but a woman carrying out hairdressing and skincare in a public place ? why , it was sure to invite a scandal . martha spent some of her savings on a lawyer , and won her case . she proudly displayed on the door of her new her salon a photograph of the barely five-foot martha as rapunzel , with hair down to her feet , but glowing with good health . her sickness , too , had proved a boon . her ambition was now propelled by christian science values . the harper method , as she came to call her services , was as much about servicing the soul as it was about cutting hair . in the therapeutic serenity of her salon , she taught that every person could glow with the kind of beauty she had , if spiritually whole and physically obedient to what she called `` the laws of cleanliness , nourishment , exercise and breathing . '' she was very practical about it . she even designed the first reclining shampoo chair , though she neglected to patent the invention . martha 's salon was a huge success . celebrities came from out of town to experience the harper method . they enjoyed the service so much that they urged her to set up a salon in their cities . and this is where martha 's ethical sense inspired her crowning innovation . instead of commissioning agents , as other innovators had done , from 1891 , she installed working-class women just like herself in salons exactly like hers , dedicated to her philosophy and her products . but these new employees were not provided a salary by martha . the women in what became a satellite network of 500 salons in america , and then europe and central america and asia , actually owned the harper 's salons . what was good enough in the nineteenth century for suffragette campaigners like susan b. anthony and was good enough in the twentieth century for woodrow wilson , calvin and grace coolidge , jacqueline kennedy , helen hayes and ladybird johnson must be good enough for the rest of the world . today , only the harper method founder 's shop remains in rochester , new york , but martha 's legacy is manifold . her health and beauty treatments have been copied , and her business model is dominant . in fact , half of retail sales in america are through martha harper 's franchising idea . so the next time you enjoy a mcdonald 's hamburger or a good night 's rest at a days inn , think of martha . because these franchises might not be the same without her inventing the model , over a century ago .
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martha had a secret ambition to go along with the secret formula : a determination to run her own business . by 1888 , serving as a maid in rochester , new york , she saved enough money -- 360 dollars -- to think of opening a public hairdressing salon . but before she could realize her dream , two blows fell .
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martha harper was sent away at age seven by her father to work as a domestic servant , her profession for 25 years until she saved enough money to start her own business . can you think of another entrepreneur or public figure with a similar rags-to-riches story ?
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hi , i ’ m john green , and this is crash course world history . let ’ s begin today with a question . why am i alive ? also , why don ’ t i have any eyes ? ah , that ’ s better . the way we answer that question ends up organizing all kinds of other thoughts , like what we should value , and how we should behave , and if we should eat meat , and whether we should dump that boy who is very nice , but insanely clingy , in a way that he can not possibly think is attractive . all of which adds up- uh , mr. green , mr. green , uh , are you talking about me ? yes , i ’ m talking about you , me from the past . i ’ m telling you that one of the reasons we study history is so that you can be a less terrible boyfriend , but more on that momentarily . [ theme music ] today we ’ re going to talk about civilizations , but in order to do that , we have to talk about talking about civilizations , because it ’ s a problematic word . so problematic , in fact , that i have to turn to camera 2 to discuss it . certain conglomerations of humans are seen as civilizations , whereas , say , nomadic cultures generally aren ’ t , unless , you are -- say it with me -- the mongols by calling some groups civilizations , you imply that all other social orders are uncivilized , which is basically just another way of saying that they ’ re savages or barbarians . side note : originally greek , the word barbarian denoted anyone who did not speak ancient greek , because to the greeks , all other languages sounded like bar bar bar bar bar bar . so , that is to say that we are all essentially barbarians , except for the classics majors , which is worth remembering when we ’ re discussing civilizations . civilizations are like most of the things we like to study , they ’ re intellectual constructs . no one woke up in the city of thebe ’ s in egypt one morning and said , “ what a beautiful morning , i sure am living at the height of egyptian civilization. ” still , they ’ re useful constructs , particularly when you ’ re comparing one civilization to another . they ’ re less useful when you ’ re comparing a civilization to a non-civilization type social order , which is why we will try to avoid that . and yes , i am getting to the good boyfriend stuff . patience , grasshopper . so what is a civilization ? well , diagnosing a civilization is a little like like diagnosing an illness . if you have four or more of the following symptoms , you might be a civilization . surplus production . once one person can make enough food to feed several people , it becomes possible to build a city , another symptom of civilization . it also leads to the specialization of labor , which in turn leads to trade . like , if everybody picks berries for a living , there ’ s no reason to trade , because i have berries , and you have berries , but if i pick berries for a living and you make hammers , suddenly , we have cause to trade . civilizations are also usually associated with social stratification , centralized government , shared values , generally in the form of religion , and writing . and at least in the early days , they were almost always associated with rivers . these days you can just bisect a segment of land horizontally and vertically , and boom , build a city . but 5000 years ago , civilizations were almost always associated with rivers . whether that ’ s the tigris and euphrates , the yellow river , the nile , the amazon basin , the coatzacoalcos - gaaah ! i was doing so good until i got to coatzacoalcos ! ( computer says : coatzacoalcos ) coatzacoalcos . maybe . why river valleys ? they ’ re flat , they ’ re well watered , and when they flood , they deposit nutrient-rich silt . we ’ ll have more to say about most of these civilizations later , but let ’ s talk about this guy , the indus valley civilization , ‘ cause it ’ s my all time favorite . the indus valley civilization was located in the flood plain of the indus and sarawati rivers , and it was about the best place in the world to have an ancient civilization because the rivers flooded very reliably twice a year , which meant that it had the most available calories per acre of pretty much anywhere on the planet . we know the indus valley civilization flourished a long time ago . probably around 3000 bce . why is that question literally hanging over my head ? but people of the indus valley were trading with mesopotamians as early as 3500 bce . we also know that it was the largest of the ancient civilizations . archaeologists have discovered more than 1500 sites . so what do we know about this civilization ? let ’ s go to the thought bubble . everything we know about the indus valley civilization comes from archaeology , because while they did use written language , we don ’ t know how to read it , and no rosetta stone has thus appeared to help us learn it . i meant the other rosetta stone , thought bubble , yeah . although , come to think of it , either would be acceptable . so here ’ s what we know , they had amazing cities . harappa and mohenjo daro are the best known , with dense , multi-story homes constructed out of uniformly sized bricks along perpendicular streets . i mean this wasn ’ t some ancient world version of houston , more like chicago . this means they must have had some form of government and zoning , but we don ’ t know what gave this government its authority . cities were oriented to catch the wind and provide a natural form of air conditioning . and they were clean . most homes were connected to a centralized drainage system that used gravity to carry waste and water out of the city in big sewer ditches that ran under the main avenues , a plumbing system that would have been the envy of many 18th century european cities . also , in mohenjo daro , the largest public building was not a temple or a palace , but a public bath , which historians call the great bath . we don ’ t know what the great bath was used for , but since later indian culture placed a huge emphasis on ritual purity , which is the basis for the caste system , some historians have speculated that the bath might have been like a giant baptismal pool . also , they traded . one of the coolest things that the indus valley civilization produced were seals used as identification markers on goods and clay tablets . these seals contained the writing that we still can ’ t decipher , and a number of fantastic designs , many featuring animals and monsters . one of the most famous and frightening is of a man with what looks like water buffalo horns on his head , sitting cross-legged between a tiger and a bull . we don ’ t know what ’ s really going on here , but it ’ s safe to say that this was a powerful dude , because he seems to be able to control the tiger . how do these seals let us know that they traded ? well , because we found them in mesopotamia , not the indus valley . plus , archaeologists have found stuff like bronze in the indus valley that is not native to the region . so what did they trade ? cotton cloth . still such a fascinating export , incidentally that it will be the subject of the 40th and final video in this very series . but here ’ s the most amazing thing about the indus valley people . they were peaceful . despite archaeologists finding 1500 sites , they have found very little evidence of warfare , almost no weapons . thanks thought bubble . ok , before we talk about the fascinating demise of the indus valley civilization . it ’ s time for the open letter . magic ! i wonder what the secret compartment has for me today ? oh ! fancy clothes . i guess the secret compartment didn ’ t think i was dressed up enough for the occasion . an open letter to historians . dear historians , the great bath ? really ? the great bath ? i ’ m trying to make history fascinating , and you give me a term that evokes scented candles , bath salts and frederic fekkai hair products ? i know sometimes the crushingly boring names of history aren ’ t your fault . you didn ’ t name the federalist papers or the austro-hungarian empire or adam smith . but when you do get a chance to name something , you go with the great bath ? not the epic bath of mohenjo daro , or the bath to end all baths , or the pool that ruled , or the moist mystery of mohenjo daro or the wet wonder ? the great bath ? really ? you can do better . best wishes , john green . so what happened to these people ? well , here ’ s what didn ’ t happen to them . they didn ’ t morph into the current residents of that area of the world , hindu indians or muslim pakistanis . those people probably came from the caucasus . instead , sometime around 1750 bce , the indus valley civilization declined until it faded into obscurity . why ? historians have three theories . one : conquest ! turns out to be a terrible military strategy not to have any weapons , and it ’ s possible people from the indus valley were completely overrun by people from the caucasus . two : environmental disaster ! it ’ s possible they brought about their own end by destroying their environment . three : earthquake ! the most interesting theory is that a massive earthquake changed the course of the rivers so much that a lot of the tributaries dried up . without adequate water supplies for irrigation , the cities couldn ’ t sustain themselves , so people literally picked up and headed for greener pastures . well , probably not pastures , it ’ s unlikely they became nomads . they probably just moved to a different plain an continued their agricultural ways . i am already boring you and i haven ’ t even told you yet how to be a better boyfriend and/or girlfriend . i ’ m going to do that now . so we don ’ t know why the indus valley civilization ended , but we also don ’ t really know why it started . why did these people build cities , and dig swimming pools , and make unnecessarily ornate seals ? were they motivated by hunger , fear , a desire for companionship , the need to be near their sacred spaces , or a general feeling that city life was just more awesome than foraging ? thinking about what motivated them to structure their life as they did helps us to think about how we structure our own lives . in short , you ’ re clingy because you ’ re motivated by fear and a need for companionship , and she finds it annoying because it ’ s enough work having to be responsible for herself without having to also be responsible for you . also , you ’ re not really helping her by clinging , and from the indus valley in the bronze age , to school life today , human life is all about collaboration . trading cloth for bronze , building cities together , and collaborating to make sure that human lives are tilted to catch the wind . next week we will travel here to discuss the hot mess o ’ potamia , but in the meantime , if you have any questions , leave them in comments , and our team of semi-trained semi-professionals will do their best to answer them . also , you ’ ll find some suggested resources in the video info below , he said , pointing at his pants . thanks for watching , and we ’ ll see you next week !
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turns out to be a terrible military strategy not to have any weapons , and it ’ s possible people from the indus valley were completely overrun by people from the caucasus . two : environmental disaster ! it ’ s possible they brought about their own end by destroying their environment .
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what are the names of the two major rivers ?
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hunger claws at your grumbling belly . it tugs at your intestines , which begin to writhe , aching to be fed . being hungry generates a powerful , often unpleasant physical sensation that 's almost impossible to ignore . after you 've reacted by gorging on your morning pancakes , you start to experience an opposing force , fullness , but how does your body actually know when you 're full ? the sensation of fullness is set in motion as food moves from your mouth down your esophagus . once it hits your stomach , it gradually fills the space . that causes the surrounding muscular wall to stretch , expanding slowly like a balloon . a multitude of nerves wrapped intricately around the stomach wall sense the stretching . they communicate with the vagus nerve up to the brainstem and hypothalamus , the main parts of the brain that control food intake . but that 's just one input your brain uses to sense fullness . after all , if you fill your stomach with water , you wo n't feel full for long . your brain also takes into account chemical messengers in the form of hormones produced by endocrine cells throughout your digestive system . these respond to the presence of specific nutrients in your gut and bloodstream , which gradually increase as you digest your food . as the hormones seep out , they 're swept up by the blood and eventually reach the hypothalamus in the brain . over 20 gastrointestinal hormones are involved in moderating our appetites . one example is cholecystokinin , which is produced in response to food by cells in the upper small bowel . when it reached the hypothalamus , it causes a reduction in the feeling of reward you get when you eat food . when that occurs , the sense of being satiated starts to sink in and you stop eating . cholecystokinin also slows down the movement of food from the stomach into the intestines . that makes your stomach stretch more over a period of time , allowing your body to register that you 're filling up . this seems to be why when you eat slowly , you actually feel fuller compared to when you consume your food at lightning speed . when you eat quickly , your body does n't have time to recognize the state it 's in . once nutrients and gastrointestinal hormones are present in the blood , they trigger the pancreas to release insulin . insulin stimulates the body 's fat cells to make another hormone called leptin . leptin reacts with receptors on neuron populations in the hypothalamus . the hypothalamus has two sets of neurons important for our feeling of hunger . one set produces the sensation of hunger by making and releasing certain proteins . the other set inhibits hunger through its own set of compounds . leptin inhibits the hypothalamus neurons that drive food intake and stimulates the neurons that suppress it . by this point , your body has reached peak fullness . through the constant exchange of information between hormones , the vagus nerve , the brainstem , and the different portions of hypothalamus , your brain gets the signal that you 've eaten enough . researchers have discovered that some foods produce more long-lasting fullness than others . for instance , boiled potatoes are ranked as some of the most hunger-satisfying foods , while croissants are particularly unsatisfying . in general , foods with more protein , fiber , and water tend to keep hunger at bay for longer . but feeling full wo n't last forever . after a few hours , your gut and brain begin their conversation again . your empty stomach produces other hormones , such as ghrelin , that increase the activity of the hunger-causing nerve cells in the hypothalamus . eventually , the growling beast of hunger is reawakened . luckily , there 's a dependable antidote for that .
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that makes your stomach stretch more over a period of time , allowing your body to register that you 're filling up . this seems to be why when you eat slowly , you actually feel fuller compared to when you consume your food at lightning speed . when you eat quickly , your body does n't have time to recognize the state it 's in .
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why is it that eating more slowly makes you feel fuller ?
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translator : tom carter reviewer : bedirhan cinar ( circus music ) [ ted n ' ed 's carnival ] [ john lloyd 's inventory of the invisible ] [ adapted from a tedtalk given by john lloyd in 2009 ] june cohen : our next speaker has spent his whole career eliciting that sense of wonder . please welcome john lloyd . ( applause ) [ hall of mirrors ] the question is , `` what is invisible ? '' there 's more of it than you think , actually . everything , i would say -- everything that matters -- except every thing , and except matter . we can see matter but we ca n't see what 's the matter . we can see the stars and the planets but we ca n't see what holds them apart , or what draws them together . with matter as with people , we see only the skin of things , we ca n't see into the engine room , we ca n't see what makes people tick , at least not without difficulty , and the closer we look at anything , the more it disappears . in fact , if you look really closely at stuff , if you look at the basic substructure of matter , there is n't anything there . electrons disappear in a kind of fuzz , and there is only energy . one of the interesting things about invisibility is , the things that we can 's see , we also ca n't understand . gravity is one thing that we ca n't see , and which we do n't understand . it 's the least understood of all the four fundamental forces , and the weakest , and nobody really knows what it is or why it 's there . for what it 's worth , sir isaac newton , the greatest scientist who ever lived , he thought jesus came to earth specifically to operate the levers of gravity . that 's what he thought he was there for . so , bright guy , could be wrong on that one , i do n't know . ( laughter ) consciousness . i see all your faces ; i 've no idea what any of you are thinking . is n't that amazing ? is n't it incredible that we ca n't read each other 's minds , when we can touch each other , taste each other , perhaps , if we get close enough , but we ca n't read each other 's minds . i find that quite astonishing . in the sufi faith , this great middle eastern religion which some claim is the root of all religions , sufi masters are all telepaths , so they say , but their main exercise of telepathy is to send out powerful signals to the rest of us that it does n't exist . so that 's why we do n't think it exists ; the sufi masters working on us . in the question of consciousness and artificial intelligence , artificial intelligence has really , like the study of consciousness , gotten nowhere , we have no idea how consciousness works . not only have they not created artificial intelligence , they have n't yet created artificial stupidity . ( laughter ) the laws of physics : invisible , eternal , omnipresent , all powerful . remind you of anyone ? interesting . i 'm , as you can guess , not a materialist , i 'm an immaterialist . and i 've found a very useful new word -- ignostic . okay ? i 'm an ignostic . [ god ? ] i refuse to be drawn on the question on whether god exists until somebody properly defines the terms . another thing we ca n't see is the human genome . and this is increasingly peculiar , because about 20 years ago when they started delving into the genome , they thought it would probably contain around 100 thousand genes . every year since , it 's been revised downwards . we now think there are likely to be just over 20 thousand genes in the human genome . this is extraordinary , because rice -- get this -- rice is known to have 38 thousand genes . potatoes have 48 chromosomes , two more than people , and the same as a gorilla . ( laughter ) you ca n't see these things , but they are very strange . the stars by day , i always think that 's fascinating . the universe disappears . the more light there is , the less you can see . time . nobody can see time . i do n't know if you know this . there 's a big movement in modern physics to decide that time does n't really exist , because it 's too inconvenient for the figures . it 's much easier if it 's not really there . you ca n't see the future , obviously , and you ca n't see the past , except in your memory . one of the interesting things about the past is you particularly ca n't see -- my son asked me this the other day , `` dad , can you remember what i was like when i was two ? and i said , `` yes . '' he said , `` why ca n't i ? '' is n't that extraordinary ? you can not remember what happened to you earlier than the age of two or three . which is great news for psychoanalysts , because otherwise they 'd be out of a job . because that 's where all the stuff happens ( laughter ) that makes you who you are . another thing you ca n't see is the grid on which we hang . this is fascinating . you probably know , some of you , that cells are continually renewed . skin flakes off , hairs grow , nails , that kind of stuff -- but every cell in your body is replaced at some point . taste buds , every ten days or so . livers and internal organs take a bit longer . spine takes several years . but at the end of seven years , not one cell in your body remains from what was there seven years ago . the question is : who then are we ? what are we ? what is this thing that we hang on ? that is actually us ? atoms , ca n't see them . nobody ever will . they 're smaller than the wavelength of light . gas , ca n't see that . interesting , somebody mentioned 1600 recently . gas was invented in 1600 by a dutch chemist called van helmont . it 's said to be the most successful ever invention of a word by a known individual . quite good . he also invented a word called `` blas , '' meaning astral radiation . did n't catch on , unfortunately . ( laughter ) but well done , him . light -- you ca n't see light . when it 's dark , in a vacuum , if a person shines a beam of light straight across your eyes , you wo n't see it . slightly technical , some physicists will disagree with this . but it 's odd that you ca n't see the beam of light , you can only see what it hits . electricity , ca n't see that . do n't let anyone tell you they understand electricity , they do n't . nobody knows what it is . ( laughter ) you probably think the electrons in an electric wire move instantaneously down a wire , do n't you , at the speed of light , when you turn the light on , they do n't . electrons bumble down the wire , about the speed of spreading honey , they say . galaxies -- hundred billion of them , estimated in the universe . hundred billion . how many can we see ? five . five , out of a hundred billion galaxies , with the naked eye . and one of them is quite difficult to see , unless you 've got very good eyesight . radio waves . there 's another thing . heinrich hertz , when he discovered radio waves , in 1887 , he called them radio waves because they radiated . somebody said to him , `` what 's the point of these , heinrich ? what 's the point of these radio waves that you 've found ? '' and he said , `` well , i 've no idea , but i guess somebody will find a use for them someday . the biggest thing that 's invisible to us is what we do n't know . it is incredible how little we know . thomas edison once said , `` we do n't know one percent of one millionth about anything . '' and i 've come to the conclusion -- because you ask this other question : `` what 's another thing we ca n't see ? '' the point , most of us . what 's the point ? the point -- what i 've got it down to is there are only two questions really worth asking . `` why are we here ? `` , and `` what should we do about it while we are ? '' to help you , i 've got two things to leave you with , from two great philosophers , perhaps two of the greatest philosopher thinkers of the 20th century . one a mathematician and engineer , and the other a poet . the first is ludwig wittgenstein , who said , `` i do n't know why we are here , but i am pretty sure it 's not in order to enjoy ourselves . '' ( laughter ) he was a cheerful bastard , was n't he ? ( laughter ) and secondly , and lastly , w.h . auden , one of my favorite poets , who said , `` we are here on earth to help others . what the others are here for , i 've no idea . '' ( laughter ) ( applause ) ( circus music ) [ get your souvenir photo here ! ] [ continue your journey into the unknown ! ] ( circus music )
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electrons bumble down the wire , about the speed of spreading honey , they say . galaxies -- hundred billion of them , estimated in the universe . hundred billion .
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according to lloyd , there are an estimated 100 billion galaxies in the known universe , but we can only see :
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in 1984 , an enterprising australian doctor named barry marshall decided to take a risk . too many of his patients were complaining of severe abdominal pain due to stomach ulcers , which are sores in the lining of the upper intestinal tract . at the time , few effective treatments for ulcers existed , and many sufferers required hospitalization or even surgery . desperate for answers , dr. marshall swallowed a cloudy broth of bacteria collected from the stomach of one of his patients . soon , dr. marshall was experiencing the same abdominal pain , bloating , and vomiting . ten days later , a camera called an endoscope peered inside his insides . marshall 's stomach was teeming with the same bacteria as his patient . he 'd also developed gastritis , or severe inflammation of the stomach , the hallmark precursor of ulcers . dr. marshall 's idea challenged a misconception that still persists to this day : that ulcers are caused by stress , food , or too much stomach acid . marshall thought the culprit was bacterial infections . initially , his idea was considered crazy by the brightest medical minds on the planet . but in 2005 , he and dr. robin warren received the ultimate validation when they were awarded the nobel prize for medicine . our stomachs are j-shaped organs with surprisingly intricate ecosystems awash in hormones and chemicals . the stomach is under constant attack by digestive enzymes , bile , proteins , microbes , and the stomach 's own acid . in response , it produces bicarbonate , mucus , and phospholipids called prostaglandins to maintain the integrity of its own lining . this delicate balance is constantly regulated and referred to as mucosal defense . since the mid-1800s , doctors thought stress alone caused most stomach ulcers . patients were given antidepressants or tranquilizers and told to visit health spas . this belief eventually shifted to the related notion of spicy foods and stress as culprits . yet no convincing study has ever demonstrated that emotional upset , psychological distress , or spicy food directly causes ulcer disease . by the mid-20th century , it was widely accepted that excess hydrochloric acid prompted the stomach to eat itself . fervent proponents of this idea were referred to as the acid mafia . the biggest hole in this theory was that antiacids only provide temporary relief . we now know that some rare ulcers are indeed caused by too much hydrochloric acid . but they make up less than 1 % of all cases . dr. marshall and dr. warren pinpointed a spiral-shaped bacteria called helicobacter pylori , or h. pylori , as the real offender . h. pylori is one of humanity 's oldest and most frequent companions , having joined us at least 50,000 years ago , and now found in 50 % of people . previously , we thought the stomach was sterile on account of it being such an acidic , hostile environment . yet h. pylori survives the acidic turmoil of the stomach with a variety of features that disrupt mucosal defense in its favor . for example , it produces an enzyme called urease that helps protect it from the surrounding gastric acid . h. pylori can make over 1,500 proteins , many of which are dedicated to maximizing its virulence . we still have unanswered questions , like why specific people develop ulcers at particular times . however , we do know individual genetics , other medical problems , use of certain medications , smoking , and the genetic diversity of helicobacter strains all play a role . in particular , certain pain medications used to reduce inflammation in joints have been discovered to work with h. pylori to create more severe stomach ulcers . dr. marshall ended up being fine after his famous , albeit dangerous , experiment . he ingested a course of antibiotics similar to the ones taken now for ulcers . to be treated by simple antibiotics is a modern triumph for a disease that previously needed surgery . marshall 's work also reminded us that scientific progress is not always smooth . but there 's value in trusting your proverbial , and sometimes literal , gut .
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but they make up less than 1 % of all cases . dr. marshall and dr. warren pinpointed a spiral-shaped bacteria called helicobacter pylori , or h. pylori , as the real offender . h. pylori is one of humanity 's oldest and most frequent companions , having joined us at least 50,000 years ago , and now found in 50 % of people .
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prior to the discovery of helicobacter pylori , which of the following were considered causes of peptic ulcers ?
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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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and how do you soothe the burn ? why does wasabi make your eyes water ? and how spicy is the spiciest spice ?
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what ’ s the difference between chilies and wasabi ?
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what if i told you that all illnesses , things like the cold , the flu , strep throat , came from wandering clouds of poisonous vapor ? you 'd probably think that absurd , and , do n't worry , it 's completely wrong . yet that 's actually what people thought caused diseases for several centuries . they called it miasma theory , and everyone from the public to the medical establishment accepted it . but by the 1840s , in the midst of devastating cholera outbreaks in london , a small group of scientists had grown skeptical . early microscopes had revealed the existence of tiny microorganisms , and they proposed that it was actually these germs that cause diseases , hence the name germ theory . though most people held onto their assumptions and strongly resisted this theory , its supporters were determined to prove them wrong by collecting compelling data . leading the charge was a physician named dr. john snow . dr . snow observed that cholera-infected patients experienced severe vomiting and diarrhea , symptoms of the gut as opposed to the lungs , and thought that perhaps the disease was transmitted through food or drink , not the air . after investigating previous outbreaks , he became convinced that cholera was spread through contaminated water sources . then , late in the summer of 1854 when cholera suddenly struck the soho district , a neighborhood in london very close to his own , dr . snow was hot on its trail . he requested the records for the deceased , and within the first week , there had already been 83 deaths . he mapped out where each of the deceased had lived and found that 73 of them resided close to the water pump on broad street . dr . snow strongly recommended shutting down the pump , and because he knew how unpopular germ theory was , he suggested that cholera was spread through a poison in the water instead of microorganisms , when presenting his case to governmental officials . they were unconvinced , but agreed to shut down the pump as an extra precaution . almost immediately , new cases of infection subsided . bolstered by his success , dr . snow was determined to connect the contaminated pump water to the disease . he found the story of a widow who had died of cholera and lived far away from soho , but had a servant bring her water from the broad street pump daily because she liked the taste . he also discovered a workhouse located around the corner from the broad street pump that housed hundreds of people , but only a handful had become infected , which dr . snow attributed to the fact that the workhouse had its own private well . finally , dr . snow heard of an infant who may have been one of the earliest victims of the outbreak . he learned that the child 's dirty diapers had been thrown into a cesspool right next to the public water pump on broad street . again , dr . snow presented his case , but even then , city officials spurned his theory , not wanting to admit that there was human waste in london 's water supply , or that they were wrong about miasma theory , which was , after all , hundreds of years old . it was n't until 1884 that dr . snow 's efforts were vindicated by dr. robert koch , who isolated the cholera-causing bacterium . koch developed a technique to grow pure cultures , and through a series of experiments , definitively proved that a specific bacterium directly cause disease . major contributions to germ theory also came from prolific scientist louis pasteur , whose study of microorganisms led to the development of the first vaccines . by challenging assumptions with data-driven research , these scientists discredited an age-old theory and sparked a revolution that was incredibly beneficial to public health . but all of this raises the question , what are the widely held scientific beliefs of today that our descendants will find ridiculous ? and as any scientist would tell you , a question is an excellent place to start .
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again , dr . snow presented his case , but even then , city officials spurned his theory , not wanting to admit that there was human waste in london 's water supply , or that they were wrong about miasma theory , which was , after all , hundreds of years old . it was n't until 1884 that dr .
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the prevailing theory for the cause of disease for hundreds of years was miasma theory . in miasma theory , what was thought to cause disease ?
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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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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 .
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do you remember the talk you had with your parents , or another trusted adult , about sex ? do you think this kind of conversation is effective for educating about sex ? if not , explain a better alternative .
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what makes something cool ? like a vintage car , or a classic product , or an iconic design ? you might say , who knows . there ’ s just something to them . this thing is totally subjective . but all of those designs you just saw were actually from the same guy -- raymond loewy . and once you understand his theory of what makes things cool , you ’ ll see it everywhere . raymond loewy was an industrial engineer who did more than maybe any other person to shape the look of america in the 20th century . his designs are everywhere : logos , trains , buses , kitchens , even outer space . loewy had a universal theory of cool : “ most advanced yet acceptable ” — or maya . people want to be trendy , but they don ’ t want to be weird . loewy ’ s trick was this : to sell something surprising , make it familiar . to sell something familiar , make it surprising . how does this work in practice ? in 1932 , raymond loewy presented a train design to pennsylvania railroad . his big idea was a single , sleek shell for the train the shape of a long bullet . but his initial design was met with great skepticism , so he decided to introduce the idea in stages . his came back with a version that was only slightly more advanced than thomas the tank engine . but his next design was more advanced , and then more advanced ... until he finally persuaded the train executives that his original , advanced version was acceptable . this is the maya method . he made the surprising feel familiar . there ’ s scientific evidence to back up these claims . one of the sturdiest findings in psychological history is known as the “ mere-exposure ” effect . in the 1960s , the psychologist robert zajonc conducted an experiment where he showed subjects nonsense words , random shapes , and chinese characters , and asked participants to pick their favorites . the subjects consistently chose the shapes and words that they 'd seen the most . exposure leads to familiarity and familiarity leads to subconscious preference . there ’ s even an explanation from evolutionary psychology : if you 're a hunter/gatherer trawling a savannah of africa and you see a plant or an animal that you recognize , that 's a good sign that it has n't killed you … at least not yet . so we have the “ acceptable ” part of raymond loewy ’ s theory -- that people naturally gravitate towards familiarity . but what about the “ advanced ” aspect ? there is another powerful idea in psychology called habituation . that means , people get tired of having to see the same thing over and over again , like a vampire movie . the power of familiarity fails when people feel like they are being forced to confront it . like having to hear that ed sheeran song for the one-thousandth time . no ! and for that reason , the power of familiarity seems to be strongest when a person is least expecting it . a case study is spotify ’ s discover weekly feature . spotify delivers a personalized playlist of 30 new songs every monday to its users . initially , the feature was supposed to include entirely new music by new artists . a bug in the algorithm accidentally let through songs that users had already heard before . so , engineers fixed the bug . and to their astonishment , engagement with the feature collapsed . they realized that people trusted new songs when they recognized old ones . to enjoy the surprising music , they needed a dash of the familiar . raymond loewy understood combining the new and the old intuitively . one of his last assignments was to help nasa design the interior of one of it 's first space stations : sky lab . he added creature comforts , like a shower and a dining room table . but his most ingenious idea was to add a small window . a viewing portal of planet earth . you have surely seen this viewing portal -- it ’ s in almost every movie about astronauts and space . it ’ s the perfect manifestation of maya : a window to a new world can also show you home . this is `` you are here '' , a new video series about the science of everyday life . tell us what you think in the comments . i 'm derek thompson , thank you for watching .
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and once you understand his theory of what makes things cool , you ’ ll see it everywhere . raymond loewy was an industrial engineer who did more than maybe any other person to shape the look of america in the 20th century . his designs are everywhere : logos , trains , buses , kitchens , even outer space .
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who was the industrial engineer mentioned in this video and said to be the creator of the look of america in the 20th century ?
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is it a flying comma , or a quotation mark chopped in half ? either way , you may already be well-versed in how to use the apostrophe , but here 's a quick refresher on its usage . the apostrophe can be used in three ways : to mark possession , to mark contraction , to mark the plural of single letters . most of the time , if you see an apostrophe hovering helpfully near a word , it 's trying to mark possession or contraction . first , let 's look at how the apostrophe marks possession . as you can see , the placement of this punctuation mark can really change the meaning of a sentence . `` those robots in the sand are my sister 's . '' `` those robots in the sand are my sisters . ' '' `` those robots in the sand are my sisters . '' when showing possession , the apostrophe belongs next to the noun that owns or possesses something . the noun can be singular or plural . proper nouns work , too . so if lucy needs to get her robots under control before they cause mayhem , those dangerous creatures would be `` lucy 's robots . '' but what if lucy was lucas ? would we write `` lucas ' robots '' or `` lucas 's robots '' ? and what if lucas gave his robots to the robinsons family ? would it be `` the robinsons ' robots , '' or `` the robinsons 's robots '' ? the truth is , even grammar nerds disagree on the right thing to do . the use of 's after a proper noun ending in s is a style issue , not a hard and fast grammar rule . it 's a conundrum without a simple answer . professional writers solve this problem by learning what 's considered correct for a publication , and doing that . the important thing is to pick one style and stick with it throughout a piece of writing . one more wrinkle . certain pronouns already have possession built in and do n't need an apostrophe . remembering that will help you avoid one of the trickiest snags in english grammar : its vs. it 's . `` it 's '' only take an apostrophe when it 's a contraction for `` it is '' or `` it has . '' if you can replace `` it 's '' with one of those two phrases , use the apostrophe . if you 're showing possession , leave it out . otherwise , contractions are pretty straightforward . the apostrophe stands in for missing letters , and lets common phrases squash into a single word . in rare cases , you can have a double contraction , though those generally are n't accepted in writing , with the exception of dialogue . so it 's possessive , it 's often followed by s 's , and it 's sometimes tricky when it comes to its usage . it 's the apostrophe .
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certain pronouns already have possession built in and do n't need an apostrophe . remembering that will help you avoid one of the trickiest snags in english grammar : its vs. it 's . `` it 's '' only take an apostrophe when it 's a contraction for `` it is '' or `` it has . ''
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one of the trickiest snags in english grammar is `` its '' versus `` it 's '' . which of the following statements is true about this conundrum ?
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if you 've got a cold , mucus is hard to miss . but what is it , and what does it do besides making you miserable ? your body produces more than a liter of mucus every day , and all the wet surfaces of your body that are not covered by skin , like your eyes , nose , mouth , lungs , and stomach get a liberal coating . that 's why they 're known as mucus membranes . mucus plays lots of roles in your body . it keeps delicate tissues from drying out and cracking , which would expose them to infection . it lubricates your eyes so you can blink . it protects your stomach lining from acid . it neutralizes threats by removing or trapping substances that could make you sick . and finally , it houses and keeps your body 's trillions of bacterial inhabitants , your microbiota , under control . mucus contains lots of different compounds , including proteins , fats , and salts . but a key component of mucus versatility is a set of proteins called mucins . mucins are the primary large molecules in mucus and are essential for giving mucus its slippery feel . they belong to a class of proteins called glycoproteins which are built out of both amino acids and sugars . in mucin , long chains of sugars are attached to specific amino acids in the protein backbone . the hydrophilic sugar chains help mucin dissolve in your body 's watery fluids . mucus , which is up to 90 % water , stays hydrated thanks to these sugar chains . some of these mucins can interact with other mucin molecules to create a complex network that establishes a barrier against pathogens and other invaders . that 's why mucus is the body 's first line of defense against foreign objects , like bacteria and dust . it 's continuously produced to clear them from the respiratory tract , like a slimy conveyor belt . this keeps bacteria from getting a solid purchase on delicate lung tissue , or making it to the blood stream , where they could cause a major infection . many of those harmful bacteria also cause diseases when they cluster into slimy growths called biofilms . but mucus contains mucins , antimicrobial peptides , antibodies , and even bacteria-hungry viruses called bacteriophages that all work together to prevent biofilms from forming . if microbes do become harmful and you get sick , the body ramps up mucus production to try to quickly flush out the offenders , and the immune system floods your mucus with extra white blood cells . in fact , the greenish mucus often associated with infections gets its color from an enzyme produced by those white blood cells . this multi-pronged approach to bacterial management is one of the main reasons why we 're not sick all the time . even though mucus protects against the infectious bacteria , the vast majority of your body 's bacterial tenants are not harmful , and many are actually beneficial . that 's particularly true when they live in mucus , where they can perform important functions , like synthesizing vitamins , suppressing harmful inflammation , and controlling the growth of more harmful species . so even though you probably associate mucus with being ill , it 's really helping you stay healthy . sure , it might seem gross , but can you think of any other substance that can lubricate , keep your body clean , fight infection , and domesticate a teeming bacterial population ? nope , just mucus .
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mucins are the primary large molecules in mucus and are essential for giving mucus its slippery feel . they belong to a class of proteins called glycoproteins which are built out of both amino acids and sugars . in mucin , long chains of sugars are attached to specific amino acids in the protein backbone .
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mucins are a special class of proteins called glycoproteins . glycoproteins are proteins that are :
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