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despite advances in medicine , cancer remains one of the most frightening diagnoses patients can receive . what makes it so difficult to cure is that it 's not one illness , but a family of over 100 diseases occurring in different types of cells . and one type of cancer has the unfortunate distinction of afflicting children more than any other type . this is leukemia , a cancer that begins in stem cells found in the bone marrow . a stem cell is a bit like an infant , undeveloped but possessing great potential . many stem cells specialize and become cells of organs , like the liver , brain and heart . but in some tissues , they can continue to divide into new stem cells throughout development , and into adulthood in order to frequently generate new cells and keep up with the body 's needs . one example is the bone marrow , where stem cells differentiate into many types of blood cells . that includes red blood cells , which carry oxygen from the lungs to all tissues , platelets , which help stop bleeding by sticking to damaged blood vessels , and white blood cells , which patrol the body , destroying potentially harmful invaders . every once in a while , something goes wrong during a stem cell 's specialization process and harmful mutations occur in the cell 's dna . cells with compromised dna are supposed to self-destruct , but some damaged cells ignore this order , replicating uncontrollably , even as they lose their original function . these are what we know as cancer cells . it is not yet clear why leukemia is the most common childhood cancer , but one contributing factor may be that leukemias are often caused by just one or two dna modifications , while most cancers require many of them , allowing leukemias to arise faster than other types of cancer . moreover , some dna alterations can occur in white blood cells during fetal development , further increasing the risk of early leukemia . but though it affects more children than any other cancer , adults constitute the majority of leukemia patients overall . once leukemia strikes , the damaged cells reproduce in the blood and the bone marrow until they take up all available space and resources . when the bone marrow can no longer produce the required amount of functional cells , the blood becomes depleted . the lack of red blood cells means that muscles do n't get enough oxygen , the reduced number of platelets is not sufficient to repair wounds , and the dearth of functional white blood cells impairs the immune system , increasing the risk of infections . to restore the normal function of the blood , leukemic cells have to be eliminated . but because leukemias are not solid tumors , they ca n't be removed surgically . instead , the cells are killed inside the body using various treatments that include chemotherapy , a combination of drugs that destroys quickly multiplying cells . unfortunately , this has the side effect of killing healthy cells , such as those found in hair follicles or intestines . and in some cases , the dosage required is so high that it kills all cells in the bone marrow , including stem cells . when this happens , the body is no longer able to create new blood cells on its own . fortunately , outside help can come in the form of stem cells from the bone marrow of a donor . once transplanted into the patient , they rapidly repopulate the bone marrow and the blood . however , bone marrow transplants are a complicated process requiring antigen compatibility between the donor and recipient to keep the transplanted cells from from attacking the patient 's own cells as foreign bodies . unlike with blood transplants , there are thousands of hla types , and even siblings and close relatives may not have compatible bone marrow . if this is the case , the search is expanded to a database containing the genetic makeup of millions of voluntary bone marrow donors . the more potential donors there are , the more patients lives can be saved through successful transplants . leukemia may be a frightening disease , but there is strength and hope in numbers .
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the lack of red blood cells means that muscles do n't get enough oxygen , the reduced number of platelets is not sufficient to repair wounds , and the dearth of functional white blood cells impairs the immune system , increasing the risk of infections . to restore the normal function of the blood , leukemic cells have to be eliminated . but because leukemias are not solid tumors , they ca n't be removed surgically .
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what is the function of platelets ?
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professor fukanō , the famous eccentric scientist and adventurer , has embarked on a new challenge : flying around the world nonstop in a plane of his own design . able to travel consistently at the incredible speed of one degree longitude around the equator per minute , the plane would take six hours to circle the world . there 's just one problem : the plane can only hold 180 kiloliters of fuel , only enough for exactly half the journey . let 's be honest . the professor probably could have designed the plane to hold more fuel , but where 's the fun in that ? instead , he 's devised a slightly more elaborate solution : building three identical planes for the mission . in addition to their speed , the professor 's equipped them with a few other incredible features . each of the planes can turn on a dime and instantly transfer any amount of its fuel to any of the others in midair without slowing down , provided they 're next to each other . the professor will pilot the first plane , while his two assistants fugōri and orokana will pilot each of the others . however , only one airport , located on the equator , has granted permission for the experiment , making it the starting point , the finish line , and the only spot where the planes can land , takeoff , or refuel on the ground . how should the three planes coordinate so the professor can fly continuously for the whole trip and achieve his dream without anyone running out of fuel and crashing ? pause here if you want to figure it out for yourself . answer in : 3 answer in : 2 answer in : 1 according to the professor 's calculations , they should be able to pull it off by a hair . the key is to maximize the support each assistant provides , not wasting a single kiloliter of fuel . it also helps us to think symmetrically so they can make shorter trips in either direction while setting the professor up for a long unsupported stretch in the middle . here 's his solution . all three planes take off at noon flying west , each fully loaded with 180 kiloliters . after 45 minutes , or one-eighth of the way around , each plane has 135 kiloliters left . orokana gives 45 to the professor and 45 to fugōri , fully refueling them both . with her remaining 45 , orokana returns to the airport and heads to the lounge for a well-deserved break . 45 minutes later , with one-quarter of the trip complete , the professor and fugōri are both at 135 kiloliters again . fugōri transfers 45 into the professor 's tank , leaving himself with the 90 he needs to return . professor fukanō stretches and puts on his favorite album . he 'll be alone for a while . in the meantime , orokana has been anxiously awaiting fugōri 's return , her plane fully refueled and ready to go . as soon as his plane touches the ground , she takes off , this time flying east . at this point , exactly 180 minutes have passed and the professor is at the halfway point of his journey with 90 kiloliters of fuel left . for the next 90 minutes , the professor and orokana 's planes fly towards each other , meeting at the three-quarter mark . just as the professor 's fuel is about the run out , he sees orokana 's plane . she gives him 45 kiloliters of her remaining 90 , leaving them with 45 each . but that 's just half of what they need to make it to the airport . fortunately , this is exactly when fugōri , having refueled , takes off . 45 minutes later , just as the other two planes are about to run empty , he meets them at the 315 degree point and transfers 45 kiloliters of fuel to each , leaving 45 for himself . all three planes land at the airport just as their fuel gauges reach zero . as the reporters and photographers cheer , the professor promises his planes will soon be available for commercial flights , just as soon as they figure out how to keep their inflight meals from spilling everywhere .
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45 minutes later , just as the other two planes are about to run empty , he meets them at the 315 degree point and transfers 45 kiloliters of fuel to each , leaving 45 for himself . all three planes land at the airport just as their fuel gauges reach zero . as the reporters and photographers cheer , the professor promises his planes will soon be available for commercial flights , just as soon as they figure out how to keep their inflight meals from spilling everywhere .
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how much total fuel ( in kiloliters ) is contained within all three airplanes when combined at the beginning of this trip ?
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what would you do if you thought your country was on the path to tyranny ? if you saw one man gaining too much power , would you try to stop him ? even if that man was one of your closest friends and allies ? these were the questions haunting roman senator marcus junius brutus in 44 bce , the year julius caesar would be assassinated . opposing unchecked power was n't just a political matter for brutus ; it was a personal one . he claimed descent from lucius junius brutus , who had helped overthrow the tyrannical king known as tarquin the proud . instead of seizing power himself , the elder brutus led the people in a rousing oath to never again allow a king to rule . rome became a republic based on the principle that no one man should hold too much power . now , four and a half centuries later , this principle was threatened . julius ceasar 's rise to the powerful position of consul had been dramatic . years of military triumphs had made him the wealthiest man in rome . and after defeating his rival pompey the great in a bitter civil war , his power was at its peak . his victories and initiatives , such as distributing lands to the poor , had made him popular with the public , and many senators vied for his favor by showering him with honors . statues were built , temples were dedicated , and a whole month was renamed , still called july today . more importantly , the title of dictator , meant to grant temporary emergency powers in wartime , had been bestowed upon caesar several times in succession . and in 44 bce , he was made dictator perpetuo , dictator for a potentially unlimited term . all of this was too much for the senators who feared a return to the monarchy their ancestors had fought to abolish , as well as those whose own power and ambition were impeded by caesar 's rule . a group of conspirators calling themselves the liberators began to secretly discuss plans for assassination . leading them were the senator gaius cassius longinus and his friend and brother-in-law , brutus . joining the conspiracy was not an easy choice for brutus . even though brutus had sided with pompey in the ill-fated civil war , caesar had personally intervened to save his life , not only pardoning him but even accepting him as a close advisor and elevating him to important posts . brutus was hesitant to conspire against the man who had treated him like a son , but in the end , cassius 's insistence and brutus 's own fear of caesar 's ambitions won out . the moment they had been waiting for came on march 15 . at a senate meeting held shortly before caesar was to depart on his next military campaign , as many as 60 conspirators surrounded him , unsheathing daggers from their togas and stabbing at him from all sides . as the story goes , caesar struggled fiercely until he saw brutus . despite the famous line , `` et tu , brute ? '' written by shakespeare , we do n't know caesar 's actual dying words . some ancient sources claim he said nothing , while others record the phrase , `` and you , child ? `` , fueling speculation that brutus may have actually been caesar 's illegitimate son . but all agree that when caesar saw brutus among his attackers , he covered his face and gave up the fight , falling to the ground after being stabbed 23 times . unfortunately for brutus , he and the other conspirators had underestimated caesar 's popularity among the roman public , many of whom saw him as an effective leader , and the senate as a corrupt aristocracy . within moments of caesar 's assassination , rome was in a state of panic . most of the other senators had fled , while the assassins barricaded themselves on the capitoline hill . mark antony , caesar 's friend and co-consul , was swift to seize the upper hand , delivering a passionate speech at caesar 's funeral days later that whipped the crowd into a frenzy of grief and anger . as a result , the liberators were forced out of rome . the ensuing power vacuum led to a series of civil wars , during which brutus , facing certain defeat , took his own life . ironically , the ultimate result would be the opposite of what the conspirators had hoped to accomplish : the end of the republic and the concentration of power under the office of emperor . opinions over the assassination of caesar were divided from the start and have remained so . as for brutus himself , few historical figures have inspired such a conflicting legacy . in dante 's `` inferno , '' he was placed in the very center of hell and eternally chewed by satan himself for his crime of betrayal . but swift 's `` gulliver 's travels '' described him as one of the most virtuous and benevolent people to have lived . the interpretation of brutus as either a selfless fighter against dictatorship or an opportunistic traitor has shifted with the tides of history and politics . but even today , over 2000 years later , questions about the price of liberty , the conflict between personal loyalties and universal ideals , and unintended consequences remain more relevant than ever .
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at a senate meeting held shortly before caesar was to depart on his next military campaign , as many as 60 conspirators surrounded him , unsheathing daggers from their togas and stabbing at him from all sides . as the story goes , caesar struggled fiercely until he saw brutus . despite the famous line , `` et tu , brute ? ''
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in shakespeares ’ play `` julius caesar , '' he attributes to caesar the final dying lines : `` et tu , brute ? '' what do the ancient sources record ? do these lines affect our reaction to brutus or caesar in any way ?
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translator : andrea mcdonough reviewer : jessica ruby when i was a kid , my understanding of the seasons was that december and january were cold and covered with snow , april and may were bursting with flowers , july and august were hot and sunshiny , and september and october were a kaleidoscope of colorful leaves . it was just the way the world worked , and it was magical . if you had told me back then that one-third of earth 's population had never seen snow or that july 4th was most definitely not a beach day , i would have thought you were crazy . but in reality , seasonal change with four distinct seasons only happens in two regions on the planet . and , even in those two , the seasons are reversed . but why ? a lot of people have heard of an astronomer called johannes kepler and how he proved that planetary orbits are elliptical and that the sun is not at the center of the orbit . it was a big deal when he figured this out several hundred years ago . his discovery solved a lot of mathematical problems that astronomers were having with planetary orbit measurements . while it 's true that our orbit 's not perfectly circular , those pictures in our science books , on tv , and in the movies give an exaggerated impression of how elongated our orbit is . in fact , earth 's orbit is very nearly a perfect circle . however , because earth 's orbit is technically an ellipse , even though it does n't look like one , and the sun is n't quite exactly at the center , it means that our distance from the sun does change through the year . ah-ha ! so , winter happens when the earth is further away from the sun ! well , no , not so fast . the earth is actually closer to the sun in january than we are in july by 5 million kilometers . january is smack-dab in the middle of the coldest season of the year for those of us up north . still not convinced ? how about this : summer and winter occur simultaneously on the surface of our planet . when it 's winter in connecticut , it 's summer in new zealand . so , if it 's not the distance from the sun , what else could it be ? well , we need to also need to know that the earth does n't sit straight up . it actually tilts . and that axial tilt of the earth is one of the main reasons for the seasons . the earth spins on an axis that 's tilted 23.5 degrees from vertical . at the same time , the earth revolves around the sun with the axis always pointing in the same direction in space . together with the tilt , the spinning and revolving causes the number of hours of daylight in a region to change as the year goes by , with more hours in summer and fewer in winter . so , when the sun is shining on the earth , it warms up . after the sun sets , it has time to cool down . so , in the summer , any location that 's about 40 degrees north of the equator , like hartford , connecticut , will get 15 hours of daylight each day and 9 hours of darkness . it warms up for longer than it cools . this happens day after day , so there is an overall warming effect . remember this fact for later ! in the winter , the opposite happens . there are many more hours of cooling time than warming time , and day after day , this results in a cooling effect . the interesting thing is , as you move north , the number of daylight hours in summer increases . so , juneau , alaska would get about 19 hours of daylight on the same summer day that tallahassee , florida gets about 14 . in fact , in the summertime at the north pole , the sun never sets . ok , then , it 's all about daylight hours , i 've got it ! well , no , there 's another important piece to this puzzle . if daylight hours were the only thing that determined average temperature , would n't the north pole be the hottest place on earth in northern summer because it receives 24 hours of daylight in the months surrounding the summer solstice ? but it 's the north pole . there 's still icebergs in the water and snow on the ground . so , what 's going on ? the earth is a sphere and so the amount of solar energy an area receives changes based on how high the sun is in the sky , which , as you know , changes during the day between sunrise and sunset . but , the maximum height also changes during the year , with the greatest solar height during the summer months and highest of all at noon on the summer solstice , which is june 21st in the northern hemisphere and december 21st in the southern hemisphere . this is because as the earth revolves , the northern hemisphere ends up tilted away from the sun in the winter and toward the sun in summer , which puts the sun more directly overhead for longer amounts of time . remember those increased summer time daylight hours ? and solar energy per square kilometer increases as the sun gets higher in the sky . so , when the sun 's at an angle , the amount of energy delivered to each square of the sunlit area is less . therefore , even though the north pole is getting 24 hours of daylight to warm up , the sunlight it receives is very spread out and delivers less energy than a place further south , where the sun is higher in the sky because it 's more tilted toward the sun . besides , the north pole has a lot to make up for . it was cooling down without any sunlight at all for 6 months straight . so , as the seasons change , wherever you are , you can now appreciate not just the beauty of each new season but the astronomical complexity that brings them to you .
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and that axial tilt of the earth is one of the main reasons for the seasons . the earth spins on an axis that 's tilted 23.5 degrees from vertical . at the same time , the earth revolves around the sun with the axis always pointing in the same direction in space .
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currently , the earth 's rotational axis is tilted by how many degrees ?
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in 479 bc , when persian soldiers besieged the greek city of potidaea , the tide retreated much farther than usual , leaving a convenient invasion route . but this was n't a stroke of luck . before they had crossed halfway , the water returned in a wave higher than anyone had ever seen , drowning the attackers . the potiidaeans believed they had been saved by the wrath of poseidon . but what really saved them was likely the same phenomenon that has destroyed countless others : a tsunami . although tsunamis are commonly known as tidal waves , they 're actually unrelated to the tidal activity caused by the gravitational forces of the sun and moon . in many ways , tsunamis are just larger versions of regular waves . they have a trough and a crest , and consist not of moving water , but the movement of energy through water . the difference is in where this energy comes from . for normal ocean waves , it comes from wind . because this only affects the surface , the waves are limited in size and speed . but tsunamis are caused by energy originating underwater , from a volcanic eruption , a submarine landslide , or most commonly , an earthquake on the ocean floor caused when the tectonic plates of the earth 's surface slip , releasing a massive amount of energy into the water . this energy travels up to the surface , displacing water and raising it above the normal sea level , but gravity pulls it back down , which makes the energy ripple outwards horizontally . thus , the tsunami is born , moving at over 500 miles per hour . when it 's far from shore , a tsunami can be barely detectable since it moves through the entire depth of the water . but when it reaches shallow water , something called wave shoaling occurs . because there is less water to move through , this still massive amount of energy is compressed . the wave 's speed slows down , while its height rises to as much as 100 feet . the word tsunami , japanese for `` harbor wave , '' comes from the fact that it only seems to appear near the coast . if the trough of a tsunami reaches shore first , the water will withdraw farther than normal before the wave hits , which can be misleadingly dangerous . a tsunami will not only drown people near the coast , but level buildings and trees for a mile inland or more , especially in low-lying areas . as if that were n't enough , the water then retreats , dragging with it the newly created debris , and anything , or anyone , unfortunate enough to be caught in its path . the 2004 indian ocean tsunami was one of the deadliest natural disasters in history , killing over 200,000 people throughout south asia . so how can we protect ourselves against this destructive force of nature ? people in some areas have attempted to stop tsunamis with sea walls , flood gates , and channels to divert the water . but these are not always effective . in 2011 , a tsunami surpassed the flood wall protecting japan 's fukushima power plant , causing a nuclear disaster in addition to claiming over 18,000 lives . many scientists and policy makers are instead focusing on early detection , monitoring underwater pressure and seismic activity , and establishing global communication networks for quickly distributing alerts . when nature is too powerful to stop , the safest course is to get out of its way .
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because there is less water to move through , this still massive amount of energy is compressed . the wave 's speed slows down , while its height rises to as much as 100 feet . the word tsunami , japanese for `` harbor wave , '' comes from the fact that it only seems to appear near the coast . if the trough of a tsunami reaches shore first , the water will withdraw farther than normal before the wave hits , which can be misleadingly dangerous . a tsunami will not only drown people near the coast , but level buildings and trees for a mile inland or more , especially in low-lying areas . as if that were n't enough , the water then retreats , dragging with it the newly created debris , and anything , or anyone , unfortunate enough to be caught in its path .
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why is ‘ tidal wave ’ not an accurate name for a tsunami ?
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some are longer than a blue whale . others are barely larger than a grain of sand . one species unleashes one of the most deadly venoms on earth . another holds a secret that 's behind some of the greatest breakthroughs in biology . they 've inhabited the ocean for at least half a billion years , and they 're still flourishing as the sea changes around them . jellyfish are soft-bodied sea creatures that are n't really fish . they 're part of a diverse team of gelatinous zooplankton , zooplankton being animals that drift in the ocean . there are more than 1,000 species of jellyfish , and many others that are often mistaken for them . a noted feature of jellyfish is a translucent bell made of a soft delicate material called mesoglea . sandwiched between two layers of skin , the mesoglea is more than 95 % water held together by protein fibers . the jellyfish can contract and relax their bells to propel themselves . they do n't have a brain or a spinal cord , but a neural net around the bell 's inner margin forms a rudimentary nervous system that can sense the ocean 's currents and the touch of other animals . jellyfish do n't have typical digestive systems , either . these gelatinous carnivores consume plankton and other small sea creatures through a hole in the underside of their bells . the nutrients are absorbed by an inner layer of cells with waste excreted back through their mouths . but the jellyfish 's relatively simple anatomy does n't prevent it from having some remarkable abilities . one kind of box jellyfish has 24 eyes . scientists think it can see color and form images within its simple nervous system . four of its eyes are curved upward on stalks . this allows the jellyfish to peer through the surface of the water , looking for the canopy of the mangrove trees where it feeds . in fact , this may be one of the only creatures with a 360-degree view of its environment . the jellyfish 's sting , which helps it capture prey and defend itself , is its most infamous calling card . in the jelly 's epidermis , cells called nematocysts lie coiled like poisonous harpoons . when they 're triggered by contact , they shoot with an explosive force . it exerts over 550 times the pressure of mike tyson 's strongest punch to inject venom into the victim . some jellyfish stings barely tingle , but others cause severe skin damage . the venom of one box jellyfish can kill a human in under five minutes , making it one of the most potent poisons of any animal in the world . other jellyfish superpowers are less lethal . one species of jellyfish glows green when it 's agitated , mostly thanks to a biofluorescent compound called green fluorescent protein , or gfp . scientists isolated the gene for gfp and figured out how to insert it into the dna of other cells . there , it acts like a biochemical beacon , marking genetic modifications , or revealing the path of critical molecules . scientists have used the glow of gfp to watch cancer cells proliferate , track the development of alzheimer 's , and illuminate countless other biological processes . developing the tools and techniques from gfp has netted three scientists a nobel prize in 2008 , and another three in 2014 . but it 's jellyfish who may be the most successful organisms on earth . ancient fossils prove that jellyfish have inhabited the seas for at least 500 million years , and maybe go back over 700 million . that 's longer than any other multiorgan animal . and as other marine animals are struggling to survive in warmer and more acidic oceans , the jellyfish are thriving , and perhaps getting even more numerous . it does n't hurt that some can lay as many as 45,000 eggs in a single night . and there 's some jellyfish whose survival strategy almost sounds like science fiction . when the immortal jellyfish is sick , aging , or under stress , its struggling cells can change their identity . the tiny bell and tentacles deteriorate and turn into an immature polyp that spawns brand new clones of the parent . as far as we know , these are the only animals who found a loophole when facing mortality . that 's pretty sophisticated for species that are 95 % water and predate the dinosaurs .
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the venom of one box jellyfish can kill a human in under five minutes , making it one of the most potent poisons of any animal in the world . other jellyfish superpowers are less lethal . one species of jellyfish glows green when it 's agitated , mostly thanks to a biofluorescent compound called green fluorescent protein , or gfp . scientists isolated the gene for gfp and figured out how to insert it into the dna of other cells .
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jellyfish derived fluorescent and bioluminescent compounds are used for all the following except :
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around the globe , there are approximately 60 million people who have been forced to leave their homes to escape war , violence , and persecution . the majority of them have become internally displaced persons , which means they have fled their homes but are still within their own countries . others have crossed a border and sought shelter outside of their own countries . they are commonly referred to as refugees . but what exactly does that term mean ? the world has known refugees for millennia , but the modern definition was drafted in the un 's 1951 convention relating to the status of refugees in response to mass persecutions and displacements of the second world war . it defines a refugee as someone who is outside their country of nationality , and is unable to return to their home country because of well-founded fears of being persecuted . that persecution may be due to their race , religion , nationality , membership in a particular social group , or political opinion , and is often related to war and violence . today , roughly half the world 's refugees are children , some of them unaccompanied by an adult , a situation that makes them especially vulnerable to child labor or sexual exploitation . each refugee 's story is different , and many must undergo dangerous journeys with uncertain outcomes . but before we get to what their journeys involve , let 's clear one thing up . there 's a lot of confusion regarding the difference between the terms `` migrant '' and `` refugee . '' `` migrants '' usually refers to people who leave their country for reasons not related to persecution , such as searching for better economic opportunities or leaving drought-stricken areas in search of better circumstances . there are many people around the world who have been displaced because of natural disasters , food insecurities , and other hardships , but international law , rightly or wrongly , only recognizes those fleeing conflict and violence as refugees . so what happens when someone flees their country ? most refugee journeys are long and perilous with limited access to shelter , water , or food . since the departure can be sudden and unexpected , belongings might be left behind , and people who are evading conflict often do not have the required documents , like visas , to board airplanes and legally enter other countries . financial and political factors can also prevent them from traveling by standard routes . this means they can usually only travel by land or sea , and may need to entrust their lives to smugglers to help them cross borders . whereas some people seek safety with their families , others attempt passage alone and leave their loved ones behind with the hopes of being reunited later . this separation can be traumatic and unbearably long . while more than half the world 's refugees are in cities , sometimes the first stop for a person fleeing conflict is a refugee camp , usually run by the united nations refugee agency or local governments . refugee camps are intended to be temporary structures , offering short-term shelter until inhabitants can safely return home , be integrated to the host country , or resettle in another country . but resettlement and long-term integration options are often limited . so many refugees are left with no choice but to remain in camps for years and sometimes even decades . once in a new country , the first legal step for a displaced person is to apply for asylum . at this point , they are an asylum seeker and not officially recognized as a refugee until the application has been accepted . while countries by and large agree on one definition of refugee , every host country is responsible for examining all requests for asylum and deciding whether applicants can be granted the status of refugee . different countries guidelines can vary substantially . host countries have several duties towards people they have recognized as refugees , like the guarantee of a minimum standard of treatment and non-discrimination . the most basic obligation towards refugees is non-refoulement , a principle preventing a nation from sending an individual to a country where their life and freedom are threatened . in reality , however , refugees are frequently the victims of inconsistent and discriminatory treatment . they 're increasingly obliged to rebuild their lives in the face of xenophobia and racism . and all too often , they are n't permitted to enter the work force and are fully dependent on humanitarian aid . in addition , far too many refugee children are out of school due to lack of funding for education programs . if you go back in your own family history , chances are you will discover that at a certain point , your ancestors were forced from their homes , either escaping a war or fleeing discrimination and persecution . it would be good of us to remember their stories when we hear of refugees currently displaced , searching for a new home .
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at this point , they are an asylum seeker and not officially recognized as a refugee until the application has been accepted . while countries by and large agree on one definition of refugee , every host country is responsible for examining all requests for asylum and deciding whether applicants can be granted the status of refugee . different countries guidelines can vary substantially .
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according to the international legal definition , a refugee is someone who :
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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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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 .
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because zombies are known for their limited , stiff movements , what kind of animation would be best to use for them ?
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translator : tom carter reviewer : bedirhan cinar in society , we have to follow laws that maintain order . did you know all chemical matter follows certain laws as well ? in fact , we can describe those laws by looking at relationships . some easy laws to begin with are the ones that govern the gases . back in 1662 , robert boyle realized that gases had an interesting response when he put them into containers and changed their volume . take an empty bottle and put the cap on it , closing that container . now squeeze your bottle , and what happens ? the pressure inside the bottle increases when the size of the container decreases . you can only crush that container so much until the gases inside push back on your hand . this is called an inverse proportion , and it changes at the same rate for every gas . boyle 's law allows chemists to predict the volume of any gas at any given pressure because the relationship is always the same . in 1780 , jacques charles noticed a different relationship between gases and their temperature . if you 've ever seen a hot-air balloon , you 've seen this law in action . when the ballons are laid out , they 're totally flat . instead of blowing the balloon up like a party balloon , they use a giant flame to heat the air inside that envelope . as the air is heated up , the balloon begins to inflate as the gas volume increases . the hotter the gas becomes , the larger the volume , and that 's charles ' law . notice this law is different from boyle 's . charles ' law is a direct relationship . as the temperature increases , the volume increases as well . the third law is also easily demonstrated . when you 're blowing up party balloons , the volume increases . as you are blowing , you 're forcing more and more gas particles into the balloon from your lungs . this causes the balloon volume to increase . this is avogadro 's law in action . as the number of particles of gas added to a container are increased , the volume will increase as well . if you add too many particles , well , you know what happens next . laws are everywhere , even in the tiniest particles of gas . if you squeeze them , the pressure will increase as the particles are pushed together . low volume means a high pressure because those particles push back . as the temperature increases , gases move away from one another , and the volume increases as well . finally , if you add gas to a closed container , that container 's volume will expand . but be careful not to add too much , because otherwise you could end up with a burst balloon .
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if you add too many particles , well , you know what happens next . laws are everywhere , even in the tiniest particles of gas . if you squeeze them , the pressure will increase as the particles are pushed together .
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why are these laws also called the “ ideal gas laws ? ” what does making assumptions allow scientists to do ? do we make other assumptions in science ? give an example .
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translator : andrea mcdonough reviewer : bedirhan cinar the human eye is one of the most powerful machines on the planet . it 's like a 500 megapixel camera that can run in bright light , in near darkness , and even under water , though not real well . it communicates to our brains so much about the world . our eyes are how we find partners , how we understand the people around us , how we read , and how we watch game shows on tv where people get knocked into cold water by padded wrecking balls . yup , the human eye is pretty neat , and we 're lucky enough to have two of them . but , there are things that , despite looking really hard , we still ca n't quite see . for example , you can watch a horse galloping , but your eyes ca n't keep up with its fast-moving hooves enough to figure out whether all four feet are ever off the ground simultaneously . for these types of questions , we need cameras . about 150 years ago , the photographer eadweard muybridge used one to solve the galloping horse mystery . using careful photography , muybridge proved that at certain points as it gallops , a horse really is flying . `` look , ma ! no hooves ! '' since then , photography has found its way into all aspects of math and science . it enhances our understanding of a world we thought we could already see , but it 's one which we really need help to see a little better . it 's not always a matter of the world moving by too quickly for our eyes to process . sometimes cameras can help us see matter or movements that are too small for the naked eye . botanists use multiple photographs to show the life cycle of plants and how flowers turn over the course of a few hours to follow the sun in what is called phototropism , growing towards the light . mathematicians have used photos to look at where in the twists and turns of a whip the crack sound comes when the whip is breaking the sound barrier . meteorologists and environmental scientists show the growth of major hurricanes and the recession over the years of many of the world 's glaciers . slow-motion film or high-speed photography have shown us the beating of a hummingbird 's wings and the course of a bullet through its target . in one project , cadavers , that 's dead bodies , were frozen and sliced into thousands of wafer-thin discs . the discs were photographed to produced animated movies that allow a viewer to travel up and down the skeleton , and into the flesh , and through the bones , and the veins , and , perhaps i should have suggested you do n't watch this during dinner , my bad . in classrooms today , the camera , now present in just about every phone and computer , allows the youngest scientists to observe the world around them , to document it , and to share their findings online . whether it 's the change of seasons or the growth of the germinating seed , cameras are allowing us to see a beautiful world through new eyes .
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for these types of questions , we need cameras . about 150 years ago , the photographer eadweard muybridge used one to solve the galloping horse mystery . using careful photography , muybridge proved that at certain points as it gallops , a horse really is flying .
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but what might this phrase mean : `` the camera certainly lies , but it tells the truth about the photographer . ''
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translator : andrea mcdonough reviewer : jessica ruby is it possible to create something out of nothing ? or , more precisely , can energy be made into matter ? yes , but only when it comes together with its twin , antimatter . and there 's something pretty mysterious about antimatter : there 's way less of it out there than there should be . let 's start with the most famous physics formula ever : e equals m c squared . it basically says that mass is concentrated energy , and mass and energy are exchangeable , like two currencies with a huge exchange rate . 90 trillion joules of energy are equivalent to 1 gram of mass . but how do i actually transform energy into matter ? the magic word is < i > energy density < /i > . if you concentrate a huge amount of energy in a tiny space , new particles will come into existence . if we look closer , we see that these particles always come in pairs , like twins . that 's because particles always have a counterpart , an antiparticle , and these are always produced in exactly equal amounts : 50/50 . this might sound like science fiction , but it 's the daily life of particle accelerators . in the collisions between two protons at cern 's large hadron collider , billions of particles and antiparticles are produced every second . consider , for example , the electron . it has a very small mass and negative electric charge . it 's antiparticle , the positron , has exactly the same mass , but a positive electric charge . but , apart from the opposite charges , both particles are identical and perfectly stable . and the same is true for their heavy cousins , the proton and the antiproton . therefore , scientists are convinced that a world made of antimatter would look , feel , and smell just like our world . in this antiworld , we may find antiwater , antigold , and , for example , an antimarble . now imagine that a marble and an antimarble are brought together . these two apparently solid objects would completely disappear into a big flash of energy , equivalent to an atomic bomb . because combining matter and antimatter would create so much energy , science fiction is full of ideas about harnessing the energy stored in antimatter , for example , to fuel spaceships like star trek . after all , the energy content of antimatter is a billion times higher than conventional fuel . the energy of one gram of antimatter would be enough for driving a car 1,000 times around the earth , or to bring the space shuttle into orbit . so why do n't we use antimatter for energy production ? well , antimatter is n't just sitting around , ready for us to harvest . we have to make antimatter before we can combust antimatter , and it takes a billion times more energy to make antimatter than you get back . but , what if there was some antimatter in outer space and we could dig it out one day from an antiplanet somewhere . a few decades ago , many scientists believed that this could actually be possible . today , observations have shown that there is no significant amount of antimatter anywhere in the visible universe , which is weird because , like we said before , there should be just as much antimatter as there is matter in the universe . since antiparticles and particles should exist in equal numbers , this missing antimatter ? now that is a real mystery . to understand what might be happening , we must go back to the big bang . in the instant the universe was created , a huge amount of energy was transformed into mass , and our initial universe contained equal amounts of matter and antimatter . but just a second later , most matter and all of the antimatter had destroyed one another , producing an enormous amount of radiation that can still be observed today . just about 100 millionths of the original amount of matter stuck around and no antimatter whatsoever . `` now , wait ! '' you might say , `` why did all the antimatter disappear and only matter was left ? '' it seems that we were somehow lucky that a tiny asymmetry exists between matter and antimatter . otherwise , there would be no particles at all anywhere in the universe and also no human beings . but what causes this asymmetry ? experiments at cern are trying to find out the reason why something exists and why we do n't live in a universe filled with radiation only ? but , so far , we just do n't know the answer .
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the energy of one gram of antimatter would be enough for driving a car 1,000 times around the earth , or to bring the space shuttle into orbit . so why do n't we use antimatter for energy production ? well , antimatter is n't just sitting around , ready for us to harvest .
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what is the energy efficiency of antiproton production at cern , approximately :
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`` order , order . so who do we have here ? '' `` your honor , this is cleopatra , the egyptian queen whose lurid affairs destroyed two of rome 's finest generals and brought the end of the republic . '' `` your honor , this is cleopatra , one of the most powerful women in history whose reign brought egypt nearly 22 years of stability and prosperity . '' `` uh , why do n't we even know what she looked like ? '' `` most of the art and descriptions came long after her lifetime in the first century bce , just like most of the things written about her . '' `` so what do we actually know ? cleopatra vii was the last of the ptolemaic dynasty , a macedonian greek family that governed egypt after its conquest by alexander the great . she ruled jointly in alexandria with her brother- to whom she was also married- until he had her exiled . '' `` but what does all this have to do with rome ? '' `` egypt had long been a roman client state , and cleopatra 's father incurred large debts to the republic . after being defeated by julius caesar in rome 's civil war , the general pompey sought refuge in egypt but was executed by cleopatra 's brother instead . '' `` caesar must have liked that . '' `` actually , he found the murder unseemly and demanded repayment of egypt 's debt . he could have annexed egypt , but cleopatra convinced him to restore her to the throne instead . '' `` we hear she was quite convincing . '' `` and why not ? cleopatra was a fascinating woman . she commanded armies at 21 , spoke several languages , and was educated in a city with the world 's finest library and some of the greatest scholars of the time . '' `` hmm . '' `` she kept caesar lounging in egypt for months when rome needed him . '' `` caesar did more than lounge . he was fascinated by egypt 's culture and knowledge , and he learned much during his time there . when he returned to rome , he reformed the calendar , commissioned a census , made plans for a public library , and proposed many new infrastructure projects . '' `` yes , all very ambitious , exactly what got him assassinated . '' `` do n't blame the queen for rome 's strange politics . her job was ruling egypt , and she did it well . she stabilized the economy , managed the vast bureaucracy , and curbed corruption by priests and officials . when drought hit , she opened the granaries to the public and passed a tax amnesty , all while preserving her kingdom 's stability and independence with no revolts during the rest of her reign . '' `` so what went wrong ? '' `` after caesar 's death , this foreign queen could n't stop meddling in roman matters . '' `` actually , it was the roman factions who came demanding her aid . and of course she had no choice but to support octavian and marc antony in avenging caesar , if only for the sake of their son . '' `` and again , she provided her particular kind of support to marc antony . '' `` why does that matter ? why does n't anyone seem to care about caesar or antony 's countless other affairs ? why do we assume she instigated the relationships ? and why are only powerful women defined by their sexuality ? '' `` order . '' `` cleopatra and antony were a disaster . they offended the republic with their ridiculous celebrations sitting on golden thrones and dressing up as gods until octavian had all of rome convinced of their megalomania . '' `` and yet octavian was the one who attacked antony , annexed egypt , and declared himself emperor . it was the roman 's fear of a woman in power that ended their republic , not the woman herself . '' `` how ironic . '' cleopatra 's story survived mainly in the accounts of her enemies in rome , and later writers filled the gaps with rumors and stereotypes . we may never know the full truth of her life and her reign , but we can separate fact from rumor by putting history on trial .
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`` and why not ? cleopatra was a fascinating woman . she commanded armies at 21 , spoke several languages , and was educated in a city with the world 's finest library and some of the greatest scholars of the time . ''
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which of these was not one of cleopatra ’ s accomplishments ?
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in medieval times , alchemists tried to achieve the seemingly impossible . they wanted to transform lowly lead into gleaming gold . history portrays these people as aged eccentrics , but if only they 'd known that their dreams were actually achievable . indeed , today we can manufacture gold on earth thanks to modern inventions that those medieval alchemists missed by a few centuries . but to understand how this precious metal became embedded in our planet to start with , we have to gaze upwards at the stars . gold is extraterrestrial . instead of arising from the planet 's rocky crust , it was actually cooked up in space and is present on earth because of cataclysmic stellar explosions called supernovae . stars are mostly made up of hydrogen , the simplest and lightest element . the enormous gravitational pressure of so much material compresses and triggers nuclear fusion in the star 's core . this process releases energy from the hydrogen , making the star shine . over many millions of years , fusion transforms hydrogen into heavier elements : helium , carbon , and oxygen , burning subsequent elements faster and faster to reach iron and nickel . however , at that point nuclear fusion no longer releases enough energy , and the pressure from the core peters out . the outer layers collapse into the center , and bouncing back from this sudden injection of energy , the star explodes forming a supernova . the extreme pressure of a collapsing star is so high , that subatomic protons and electrons are forced together in the core , forming neutrons . neutrons have no repelling electric charge so they 're easily captured by the iron group elements . multiple neutron captures enable the formation of heavier elements that a star under normal circumstances ca n't form , from silver to gold , past lead and on to uranium . in extreme contrast to the million year transformation of hydrogen to helium , the creation of the heaviest elements in a supernova takes place in only seconds . but what becomes of the gold after the explosion ? the expanding supernova shockwave propels its elemental debris through the interstellar medium , triggering a swirling dance of gas and dust that condenses into new stars and planets . earth 's gold was likely delivered this way before being kneaded into veins by geothermal activity . billions of years later , we now extract this precious product by mining it , an expensive process that 's compounded by gold 's rarity . in fact , all of the gold that we 've mined in history could be piled into just three olympic-size swimming pools , although this represents a lot of mass because gold is about 20 times denser than water . so , can we produce more of this coveted commodity ? actually , yes . using particle accelerators , we can mimic the complex nuclear reactions that create gold in stars . but these machines can only construct gold atom by atom . so it would take almost the age of the universe to produce one gram at a cost vastly exceeding the current value of gold . so that 's not a very good solution . but if we were to reach a hypothetical point where we 'd mined all of the earth 's buried gold , there are other places we could look . the ocean holds an estimated 20 million tons of dissolved gold but at extremely miniscule concentrations making its recovery too costly at present . perhaps one day , we 'll see gold rushes to tap the mineral wealth of the other planets of our solar system . and who knows ? maybe some future supernova will occur close enough to shower us with its treasure and hopefully not eradicate all life on earth in the process .
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actually , yes . using particle accelerators , we can mimic the complex nuclear reactions that create gold in stars . but these machines can only construct gold atom by atom . so it would take almost the age of the universe to produce one gram at a cost vastly exceeding the current value of gold . so that 's not a very good solution .
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how long would it take to make a gram of gold with a particle accelerator ?
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they 're everywhere , but you will never see one . trillions of them are flying through you right this second , but you ca n't feel them . these ghost particles are called neutrinos and if we can catch them , they can tell us about the furthest reaches and most extreme environments of the universe . neutrinos are elementary particles , meaning that they ca n't be subdivided into other particles the way atoms can . elementary particles are the smallest known building blocks of everything in the universe , and the neutrino is one of the smallest of the small . a million times less massive than an electron , neutrinos fly easily through matter , unaffected by magnetic fields . in fact , they hardly ever interact with anything . that means that they can travel through the universe in a straight line for millions , or even billions , of years , safely carrying information about where they came from . so where do they come from ? pretty much everywhere . they 're produced in your body from the radioactive decay of potassium . cosmic rays hitting atoms in the earth 's atmosphere create showers of them . they 're produced by nuclear reactions inside the sun and by radioactive decay inside the earth . and we can generate them in nuclear reactors and particle accelerators . but the highest energy neutrinos are born far out in space in environments that we know very little about . something out there , maybe supermassive black holes , or maybe some cosmic dynamo we 've yet to discover , accelerates cosmic rays to energies over a million times greater than anything human-built accelerators have achieved . these cosmic rays , most of which are protons , interact violently with the matter and radiation around them , producing high-energy neutrinos , which propagate out like cosmic breadcrumbs that can tell us about the locations and interiors of the universe 's most powerful cosmic engines . that is , if we can catch them . neutrinos ' limited interactions with other matter might make them great messengers , but it also makes them extremely hard to detect . one way to do so is to put a huge volume of pure transparent material in their path and wait for a neutrino to reveal itself by colliding with the nucleus of an atom . that 's what 's happening in antarctica at icecube , the world 's largest neutrino telescope . it 's set up within a cubic kilometer of ice that has been purified by the pressure of thousands of years of accumulated ice and snow , to the point where it 's one of the clearest solids on earth . and even though it 's shot through with boreholes holding over 5,000 detectors , most of the cosmic neutrinos racing through icecube will never leave a trace . but about ten times a year , a single high-energy neutrino collides with a molecule of ice , shooting off sparks of charged subatomic particles that travel faster through the ice than light does . in a similar way to how a jet that exceeds the speed of sound produces a sonic boom , these superluminal charged particles leave behind a cone of blue light , kind of a photonic boom . this light spreads through icecube , hitting some of its detectors located over a mile beneath the surface . photomultiplier tubes amplify the signal , which contains information about the charged particles ' paths and energies . the data are beamed to astrophysicists around the world who look at the patterns of light for clues about the neutrinos that produced them . these super energetic collisions are so rare that icecube 's scientists give each neutrino nicknames , like big bird and dr. strangepork . icecube has already observed the highest energy cosmic neutrinos ever seen . the neutrinos it detects should finally tell us where cosmic rays come from and how they reached such extreme energies . light , from infrared , to x-rays , to gamma rays , has given us increasingly energetic and continuously surprising views of the universe . we are now at the dawn of the age of neutrino astronomy , and we have no idea what revelations icecube and other neutrino telescopes may bring us about the universe 's most violent , most energetic phenomena .
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the data are beamed to astrophysicists around the world who look at the patterns of light for clues about the neutrinos that produced them . these super energetic collisions are so rare that icecube 's scientists give each neutrino nicknames , like big bird and dr. strangepork . icecube has already observed the highest energy cosmic neutrinos ever seen . the neutrinos it detects should finally tell us where cosmic rays come from and how they reached such extreme energies .
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why is icecube at the south pole ?
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three and a half thousand years ago in egypt , a noble pharaoh was the victim of a violent attack . but the attack was not physical . this royal had been dead for 20 years . the attack was historical , an act of damnatio memoriae , the damnation of memory . somebody smashed the pharaoh 's statues , took a chisel and attempted to erase the pharaoh 's name and image from history . who was this pharaoh , and what was behind the attack ? here 's the key : the pharaoh hatshepsut was a woman . in the normal course of things , she should never have been pharaoh . although it was legal for a woman to be a monarch , it disturbed some essential egyptian beliefs . firstly , the pharaoh was known as the living embodiment of the male god horus . secondly , disturbance to the tradition of rule by men was a serious challenge to maat , a word for `` truth , '' expressing a belief in order and justice , vital to the egyptians . hatshepsut had perhaps tried to adapt to this belief in the link between order and patriarchy through her titles . she took the name maatkare , and sometimes referred to herself as hatshepsu , with a masculine word ending . but apparently , these efforts did n't convince everyone , and perhaps someone erased hatshepsut 's image so that the world would forget the disturbance to maat , and egypt could be balanced again . hatshepsut , moreover , was not the legitimate heir to the thrown , but a regent , a kind of stand-in co-monarch . the egyptian kingship traditionally passed from father to son . it passed from thutmose i to his son thutmose ii , hatshepsut 's husband . it should have passed from thutmose ii directly to his son thutmose iii , but thutmose iii was a little boy when his father died . hatshepsut , the dead pharaoh 's chief wife and widow , stepped in to help as her stepson 's regent but ended up ruling beside him as a fully fledged pharaoh . perhaps thutmose iii was angry about this . perhaps he was the one who erased her images . it 's also possible that someone wanted to dishonor hatshepsut because she was a bad pharaoh . but the evidence suggests she was actually pretty good . she competently fulfilled the traditional roles of the office . she was a great builder . her mortuary temple , djeser-djeseru , was an architectural phenomenon at the time and is still admired today . she enhanced the economy of egypt , conducting a very successful trade mission to the distant land of punt . she had strong religious connections . she even claimed to be the daughter of the state god , amun . and she had a successful military career , with a nubian campaign , and claims she fought alongside her soldiers in battle . of course , we have to be careful when we assess the success of hatshepsut 's career , since most of the evidence was written by hatshepsut herself . she tells her own story in pictures and writing on the walls of her mortuary temple and the red chapel she built for amun . so who committed the crimes against hatshepsut 's memory ? the most popular suspect is her stepson , nephew and co-ruler , thutmose iii . did he do it out of anger because she stole his throne ? this is unlikely since the damage was n't done until 20 years after hatshepsut died . that 's a long time to hang onto anger and then act in a rage . maybe thutmose iii did it to make his own reign look stronger . but it is most likely that he or someone else erased the images so that people would forget that a woman ever sat on egypt 's throne . this gender anomaly was simply too much of a threat to maat and had to be obliterated from history . happily , the ancient censors were not quite thorough enough . enough evidence survived for us to piece together what happened , so the story of this unique powerful woman can now be told .
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she was a great builder . her mortuary temple , djeser-djeseru , was an architectural phenomenon at the time and is still admired today . she enhanced the economy of egypt , conducting a very successful trade mission to the distant land of punt .
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what is the name of hatshepsut 's mortuary temple ?
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think back to a really vivid memory . got it ? okay , now try to remember what you had for lunch three weeks ago . that second memory probably is n't as strong , but why not ? why do we remember some things , and not others ? and why do memories eventually fade ? let 's look at how memories form in the first place . when you experience something , like dialing a phone number , the experience is converted into a pulse of electrical energy that zips along a network of neurons . information first lands in short term memory , where it 's available from anywhere from a few seconds to a couple of minutes . it 's then transferred to long-term memory through areas such as the hippocampus , and finally to several storage regions across the brain . neurons throughout the brain communicate at dedicated sites called synapses using specialized neurotransmitters . if two neurons communicate repeatedly , a remarkable thing happens : the efficiency of communication between them increases . this process , called long term potentiation , is considered to be a mechanism by which memories are stored long-term , but how do some memories get lost ? age is one factor . as we get older , synapses begin to falter and weaken , affecting how easily we can retrieve memories . scientists have several theories about what 's behind this deterioration , from actual brain shrinkage , the hippocampus loses 5 % of its neurons every decade for a total loss of 20 % by the time you 're 80 years old to the drop in the production of neurotransmitters , like acetylcholine , which is vital to learning and memory . these changes seem to affect how people retrieve stored information . age also affects our memory-making abilities . memories are encoded most strongly when we 're paying attention , when we 're deeply engaged , and when information is meaningful to us . mental and physical health problems , which tend to increase as we age , interfere with our ability to pay attention , and thus act as memory thieves . another leading cause of memory problems is chronic stress . when we 're constantly overloaded with work and personal responsibilites , our bodies are on hyperalert . this response has evolved from the physiological mechanism designed to make sure we can survive in a crisis . stress chemicals help mobilize energy and increase alertness . however , with chronic stress our bodies become flooded with these chemicals , resulting in a loss of brain cells and an inability to form new ones , which affects our ability to retain new information . depression is another culprit . people who are depressed are 40 % more likely to develop memory problems . low levels of serotonin , a neurotransmitter connected to arousal , may make depressed individuals less attentive to new information . dwelling on sad events in the past , another symptom of depression , makes it difficult to pay attention to the present , affecting the ability to store short-term memories . isolation , which is tied to depression , is another memory thief . a study by the harvard school of public health found that older people with high levels of social integration had a slower rate of memory decline over a six-year period . the exact reason remains unclear , but experts suspect that social interaction gives our brain a mental workout . just like muscle strength , we have to use our brain or risk losing it . but do n't despair . there are several steps you can take to aid your brain in preserving your memories . make sure you keep physically active . increased blood flow to the brain is helpful . and eat well . your brain needs all the right nutrients to keep functioning correctly . and finally , give your brain a workout . exposing your brain to challenges , like learning a new language , is one of the best defenses for keeping your memories intact .
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why do we remember some things , and not others ? and why do memories eventually fade ? let 's look at how memories form in the first place .
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we can do the following to preserve our memories except :
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it 's often said that despite humanity 's many conflicts , we all bleed the same blood . it 's a nice thought but not quite accurate . in fact , our blood comes in a few different varieties . our red blood cells contain a protein called hemoglobin that binds to oxygen , allowing the cells to transport it throughout the body . but they also have another kind of complex protein on the outside of the cell membrane . these proteins , known as antigens , communicate with white blood cells , immune cells that protect against infection . antigens serve as identifying markers , allowing the immune system to recognize your body 's own cells without attacking them as foreign bodies . the two main kinds of antigens , a and b , determine your blood type . but how do we get four blood types from only two antigens ? well , the antigens are coded for by three different alleles , varieties of a particular gene . while the a and b alleles code for a and b antigens , the o allele codes for neither , and because we inherit one copy of each gene from each parent , every individual has two alleles determining blood type . when these happen to be different , one overrides the other depending on their relative dominance . for blood types , the a and b alleles are both dominant , while o is recessive . so a and a gives you type a blood , while b and b gives you type b . if you inherit one of each , the resulting codominance will produce both a and b antigens , which is type ab . the o allele is recessive , so either of the others will override it when they 're paired , resulting in either type a or type b . but if you happen to inherit two os , instructions will be expressed that make blood cells without the a or the b antigen . because of these interactions , knowing both parents ' blood types lets us predict the relative probability of their children 's blood types . why do blood types matter ? for blood transfusions , finding the correct one is a matter of life and death . if someone with type a blood is given type b blood , or vice versa , their antibodies will reject the foreign antigens and attack them , potentially causing the transfused blood to clot . but because people with type ab blood produce both a and b antigens , they do n't make antibodies against them , so they will recognize either as safe , making them universal recipients . on the other hand , people with blood type o do not produce either antigen , which makes them universal donors , but will cause their immune system to make antibodies that reject any other blood type . unfortunately , matching donors and recipients is a bit more complicated due to additional antigen systems , particular the rh factor , named after the rhesus monkeys in which it was first isolated . rh+ or rh- refers to the presence or absence of the d antigen of the rh blood group system . and in addition to impeding some blood transfusions , it can cause severe complications in pregnancy . if an rh- mother is carrying an rh+ child , her body will produce rh antibodies that may cross the placenta and attack the fetus , a condition known as hemolytic disease of the newborn . some cultures believe blood type to be associated with personality , though this is not supported by science . and though the proportions of different blood types vary between human populations , scientists are n't sure why they evolved ; perhaps as protection against blood born diseases , or due to random genetic drift . finally , different species have different sets of antigens . in fact , the four main blood types shared by us apes seem paltry in comparison to the thirteen types found in dogs .
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and though the proportions of different blood types vary between human populations , scientists are n't sure why they evolved ; perhaps as protection against blood born diseases , or due to random genetic drift . finally , different species have different sets of antigens . in fact , the four main blood types shared by us apes seem paltry in comparison to the thirteen types found in dogs .
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what are antigens ?
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( music ) sometimes when i 'm on a long plane flight , i gaze out at all those mountains and deserts and try to get my head around how vast our earth is . and then i remember that there 's an object we see every day that would literally fit one million earths inside it . the sun seems impossibly big , but in the great scheme of things , it 's a pinprick , one of about 400 billion stars in the milky way galaxy , which you can see on a clear night as a pale , white mist stretched across the sky . and it gets worse . there are maybe 100 billion galaxies detectable by our telescopes , so if each star was the size of a single grain of sand , just the milky way has enough stars to fill a 30 foot by 30 foot stretch of beach three feet deep with sand . and the entire earth does n't have enough beaches to represent the stars in the overall universe . such a beach would continue for literally hundreds of millions of miles . holy stephen hawking , that is a lot of stars . but he and other physicists now believe in a reality that is unimaginably bigger still . i mean , first of all , the 100 billion galaxies within range of our telescopes are probably a minuscule fraction of the total . space itself is expanding at an accelerating pace . the vast majority of the galaxies are separating from us so fast that light from them may never reach us . still , our physical reality here on earth is intimately connected to those distant , invisible galaxies . we can think of them as part of our universe . they make up a single , giant edifice , obeying the same physical laws and all made from the same types of atoms , electrons , protons , quarks , neutrinos that make up you and me . however , recent theories in physics , including one called string theory , are now telling us there could be countless other universes , built on different types of particles , with different properties , obeying different laws . most of these universes could never support life , and might flash in and out of existence in a nanosecond , but nonetheless , combined they make up a vast multiverse of possible universes . in up to 11 dimensions , featuring wonders beyond our wildest imagination . and the leading version of string theory predicts a multiverse made of up to 10 to the 500 universes . that 's a one followed by 500 zeroes , a number so vast that if every atom in our observable universe had its own universe and all of the atoms in all of those universes each had their own universe , and you repeated that for two more cycles , you 'd still be at a tiny fraction of the total -- namely , one trillion trillion trillion trillion trillion trillion trillion trillion trillion trillion trillion trillion trillion trillion trillionth . but even that number is minuscule compared to another number : infinity . some physicists think the space-time continuum is literally infinite , and that it contains an infinite number of so-called pocket universes with varying properties . how 's your brain doing ? but quantum theory adds a whole new wrinkle . i mean , the theory 's been proven true beyond all doubt , but interpreting it is baffling . and some physicists think you can only un-baffle it if you imagine that huge numbers of parallel universes are being spawned every moment , and many of these universes would actually be very like the world we 're in , would include multiple copies of you . in one such universe , you 'd graduate with honors and marry the person of your dreams . in another , not so much . there are still some scientists who would say , hogwash . the only meaningful answer to the question of how many universes there are is one , only one universe . and a few philosophers and mystics might argue that even our own universe is an illusion . so , as you can see , right now there is no agreement on this question , not even close . all we know is , the answer is somewhere between zero and infinity . well , i guess we know one other thing : this is a pretty cool time to be studying physics . we just might be undergoing the biggest paradigm shift in knowledge that humanity has ever seen .
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well , i guess we know one other thing : this is a pretty cool time to be studying physics . we just might be undergoing the biggest paradigm shift in knowledge that humanity has ever seen .
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anderson says we may be experiencing a giant paradigm shift in knowledge . what other paradigm shifts in our knowledge can you think of ?
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one day the universe will die . but why ? and how ? and will the universe be dead forever ? and how do we know that ? first of all , the universe is expanding . and not only that , the rate of its expansion is accelerating . the reason : dark energy . dark energy is a strange phenomenon that scientists believe permeates the universe . until 1998 we thought that the universe must work a bit like a ball that you throw into the sky . the ball moves up , but at some point it has to come down again . but the expansion of the universe is actually speeding up . that ’ s like throwing a ball up and watching it fly away faster and faster and faster . where is this acceleration coming from ? well , we don ’ t know , but we call it “ dark energy ” . einstein thought of it first and then decided it was stupid . now , astrophysicists have decided it is plausible . trouble is , this is all very theoretical , and we don ’ t actually know what the properties of dark energy are . but there are various theories and they lead us to three scenarios for the end of the universe . one : the big rip . since its birth , the universe has been expanding . for unknown reasons new spaces created everywhere equally . the space between galaxies expands , so they move apart . the space inside galaxies also expands , but here , gravity is strong enough to keep them together . in the big rip scenario , the expansion accelerates up to a point where space expands so fast that gravity can ’ t compensate for this effect anymore . the result is a big rip . at first , only large structures like galaxies are torn apart , since space between the single objects expands very fast . next , big bodies like black holes , stars , and planets die . their gravity isn ’ t strong enough to keep them together , so they dissolve into their components . in the end , space would expand faster than the speed of light . atoms would now be affected , and they would just disband . once space is expanding faster than light , no particle in the universe can interact with any other particle anymore . the universe would dissolve into countless lonely particles that won ’ t be able to touch anything else in a strange , timeless universe . hmm , and you thought you felt lonely ! two : heat death or a big freeze . in a nutshell , the difference between the big rip and heat death is that in a heat death scenario matter stays intact and is converted over an incredibly long but finite period of time into radiation , while the universe expands forever . but how does this work ? let ’ s talk about entropy . every system tends towards the state of highest entropy , like when we have a latte macchiato . initially , it has different regions , but over time , they will cool down and disintegrate , until it ’ s uniform . and this also applies to the universe . so , while the universe gets bigger and bigger , matters slowly decays and spreads out . at some point , after lots of generations of stars , all the gas clouds necessary to form stars will be exhausted , so the universe will turn dark . the remaining suns will die ; black holes will slowly degenerate and evaporate over trillions of years due to what ’ s known as hawking radiation . when this process is complete , only a dilute gas of photons and light particles remains , until even this decays . all activity in the universe ceases at this point ; entropy is at its maximum and the universe is dead forever . unless… theoretically , it might be possible that after an incredibly long amount of time , there might be a spontaneous entropy decrease as a result of something called “ quantum tunneling ” , leading to a new big bang . three : big crunch and big bounce . this is the most uplifting scenario . if there is less dark energy than we think or it decreases over time , gravity will be the dominating force in the universe one day . in a few trillion years , the rate of expansion of the universe will slow down and stop . after that , it reverses . galaxies will race at each other , merging as the universe becomes smaller and smaller . since a smaller universe also means a hotter universe , temperatures rise everywhere all at once . one hundred thousand years before the big crunch , background radiation would be hotter than the surfaces of the most stars , which means that they would be cooked from the outside . minutes before the big crunch happens , atom cores are ripped apart , before supermassive black holes devour everything . finally , all black holes would emerge into a supermassive mega-black hole that contains the entire mass of the universe , and in the last moment before the big crunch it would devour the universe , including itself . the big bounce theory states that this has happened a lot of times and that the universe goes through an infinite cycle of expansion and contraction . well , wouldn ’ t that be nice ? so what will actually happen to the universe in the end ? at the moment , heat death seems the most likely , but we at kurzgesagt hope that this “ dead forever ” stuff is wrong and the universe will start over and over again . we do n't know for sure either way , so let ’ s just assume the most uplifting theory is true . by the way , we have a twitter account . subtitles by the amara.org community
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their gravity isn ’ t strong enough to keep them together , so they dissolve into their components . in the end , space would expand faster than the speed of light . atoms would now be affected , and they would just disband .
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in the big rip scenario at what speed would space expand ?
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in the third act of `` swan lake , '' the black swan pulls off a seemingly endless series of turns , bobbing up and down on one pointed foot and spinning around , and around , and around 32 times . it 's one of the toughest sequences in ballet , and for those thirty seconds or so , she 's like a human top in perpetual motion . those spectacular turns are called fouettés , which means `` whipped '' in french , describing the dancer 's incredible ability to whip around without stopping . but while we 're marveling at the fouetté , can we unravel its physics ? the dancer starts the fouetté by pushing off with her foot to generate torque . but the hard part is maintaining the rotation . as she turns , friction between her pointe shoe and the floor , and somewhat between her body and the air , reduces her momentum . so how does she keep turning ? between each turn , the dancer pauses for a split second and faces the audience . her supporting foot flattens , and then twists as it rises back onto pointe , pushing against the floor to generate a tiny amount of new torque . at the same time , her arms sweep open to help her keep her balance . the turns are most effective if her center of gravity stays constant , and a skilled dancer will be able to keep her turning axis vertical . the extended arms and torque-generating foot both help drive the fouetté . but the real secret and the reason you hardly notice the pause is that her other leg never stops moving . during her momentary pause , the dancer 's elevated leg straightens and moves from the front to the side , before it folds back into her knee . by staying in motion , that leg is storing some of the momentum of the turn . when the leg comes back in towards the body , that stored momentum gets transferred back to the dancer 's body , propelling her around as she rises back onto pointe . as the ballerina extends and retracts her leg with each turn , momentum travels back and forth between leg and body , keeping her in motion . a really good ballerina can get more than one turn out of every leg extension in one of two ways . first , she can extend her leg sooner . the longer the leg is extended , the more momentum it stores , and the more momentum it can return to the body when it 's pulled back in . more angular momentum means she can make more turns before needing to replenish what was lost to friction . the other option is for the dancer to bring her arms or leg in closer to her body once she returns to pointe . why does this work ? like every other turn in ballet , the fouetté is governed by angular momentum , which is equal to the dancer 's angular velocity times her rotational inertia . and except for what 's lost to friction , that angular momentum has to stay constant while the dancer is on pointe . that 's called conservation of angular momentum . now , rotational inertia can be thought of as a body 's resistance to rotational motion . it increases when more mass is distributed further from the axis of rotation , and decreases when the mass is distributed closer to the axis of rotation . so as she brings her arms closer to her body , her rotational inertia shrinks . in order to conserve angular momentum , her angular velocity , the speed of her turn , has to increase , allowing the same amount of stored momentum to carry her through multiple turns . you 've probably seen ice skaters do the same thing , spinning faster and faster by drawing in their arms and legs . in tchaikovsky 's ballet , the black swan is a sorceress , and her 32 captivating fouettés do seem almost supernatural . but it 's not magic that makes them possible . it 's physics .
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and except for what 's lost to friction , that angular momentum has to stay constant while the dancer is on pointe . that 's called conservation of angular momentum . now , rotational inertia can be thought of as a body 's resistance to rotational motion .
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fouettés are governed by the conservation of :
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what gives the trumpet its clarion ring and the tuba its gut-shaking `` omm pah pah ? '' and what makes the trombone so jazzy ? the answer lies not in the brass these instruments are made of , but in the journey air takes from the musician 's lungs to the instrument 's bell . like any sound , music consists of vibrations traveling through air . instruments are classified based on how those vibrations are produced . percussion instruments are struck . string instruments are plucked or bowed . woodwinds have air blown against a reed or sharp edge . for brass instruments , however , the vibration come directly from the musician 's mouth . one of the first things a brass player must learn is to breathe in deeply , until every possible particle of air is crammed into the lungs . once all that air is inside , it must come out through the mouth , but there , an internal battle takes place as the musician simultaneously tries to hold their lips firmly closed while blowing enough air to force them open . the escaping air meets resistance from the lip muscles , forms an opening called the aperture and creates the vibration that brass players call `` the buzz . '' when a mouthpiece is held up to those vibrating lips , it slightly refines the buzz , amplifying the vibration at certain frequencies . but things get really interesting depending on what instrument is attached to that mouthpiece . a brass instrument 's body is essentially a tube that resonates with the air column blowing through it . the way that sound waves travel through this column forms a limited pattern of pitches known as the harmonic series , with notes spaced far apart at the lower end , but coming closer together as the pitch increases . the musician can alter the pitch of the note through slight contractions of the lips and alterations to air volume and speed . slower , warm sighing air produces lower pitches , and faster , cool , flowing air produces higher pitches in the series . but any single harmonic series has gaps where pitches are missing and the versatility of brass instruments lies in their ability to switch between multiple series . on instruments like the trumpet , valves can be lowered to increase the length of tubing the air travels through , while on a trombone , this is done by extending its slide . lengthening the tube stretches the vibrating air column , reducing the frequency of vibrations and resulting in a lower pitch . this is why the tuba , the largest brass instrument , is also the one capable of playing the lowest notes . so changing the instrument length shifts its harmonic series , while slight variations of the air flow and the player 's lips produce the different notes within it . and those notes finally emerge through the flared bell opening at the end . what started as a deep breath and a vibrating buzz on the lips has now been transformed into a bold and brassy tune . the musician 's skillful manipulation of every part of the process from lungs , to lips , to the mouthpiece , to the instrument itself creates an amazing palette of pitches that can be heard in musical genres across the globe . by harnessing the power of natural resonance in a flexible and controllable way , brass instruments are great examples of the fusion of human creativity with the physics of our world .
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lengthening the tube stretches the vibrating air column , reducing the frequency of vibrations and resulting in a lower pitch . this is why the tuba , the largest brass instrument , is also the one capable of playing the lowest notes . so changing the instrument length shifts its harmonic series , while slight variations of the air flow and the player 's lips produce the different notes within it .
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the brass instrument capable of playing the lowest notes is the _____ .
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translator : andrea mcdonough reviewer : bedirhan cinar pretty much everyone loves eating pizza , but it can be a messy business . pizza is soft and bendable . so how can you stop all that cheese from falling off ? you might know some tricks : you can use two hands -- not so classy , or you can use a paper plate and allow only the tip of the pizza to peek out . there 's one other trick , though : holding the crust , you can sort of fold the slice down the middle . now the tip of the pizza is n't falling over , and you can eat it without getting tomato sauce all over yourself or accidentally biting off some of that paper plate . but why should the tip stay up just because you bent the crust ? to understand this , you need to know two things : a little bit about the math of curved shapes and a little about the physics of thin sheets . first , the math . suppose i have a flat sheet made out of rubber . it 's really thin and bendable , so it 's easy to roll into a cylinder . i do n't need to stretch the sheet at all , just bend it . this property where one shape can be transformed into another without stretching or crumpling , is called isometry . a mathematician would say that a flat sheet is isometric to a cylinder . but not all shapes are isometric . if i try to turn my flat sheet into part of a sphere , there 's no way i can do it . you can check this for yourself , by trying to fit a flat sheet of paper onto a soccer ball without stretching or crumpling the paper . it 's just not possible . so a mathematician would say that a flat sheet and a sphere are n't isometric . there 's one more familiar shape that is n't isometric to any of the shapes we 've seen so far : a potato chip . potato chip shapes are n't isometric to flat sheets . if you want to get a flat piece of rubber into the shape of a potato chip , you need to stretch it -- not just bend it , but stretch it as well . so , that 's the math . not so hard , right ? now for the physics . it can be summed up in one sentence : thin sheets are easy to bend but hard to stretch . this is really important . thin sheets are easy to bend but hard to stretch . remember when we rolled our flat sheet of rubber into a cylinder ? that was n't hard , right ? but imagine how hard you 'd have pull on the sheet to increase its area by 10 percent . it would be pretty difficult . the point is that bending a thin sheet takes a relatively small amount of force , but stretching or crumbling a thin sheet is much harder . now , finally , we get to talk about pizza . suppose you go down to the pizzeria and buy yourself a slice . you pick it up from the crust , first , without doing the fold . because of gravity , the slice bends downwards . pizza is pretty thin , after all , and we know that thin sheets are easy to bend . you ca n't get it in your mouth , cheese and tomato sauce dripping everywhere -- it 's a big mess . so you fold the crust . when you do , you force the pizza into something like a taco shape . that 's not hard to do -- after all , this shape is isometric to the original pizza , which was flat . but imagine what would happen if the pizza were to droop down while you 're bending it . now it looks like a droopy taco . and what does a droopy taco look like ? a potato chip ! but we know that potato chips are not isometric to flat pieces of rubber or flat pizzas , and that means that in order to get into the shape it 's in now , the slice of pizza had to stretch . since the pizza is thin , this takes a lot of force , compared to the amount of force it takes to bend the pizza in the first place . so , what 's the conclusion ? when you fold the pizza at the crust , you make it into a shape where a lot of force is needed to bend the tip down . often gravity is n't strong enough to provide this force . that was kind of a lot of information , so let 's do a quick backwards recap . when pizza is folded at the crust , gravity is n't strong enough to bend the tip . why ? because stretching a pizza is hard . and to bend the tip downwards , the pizza would have to stretch , because the shape the pizza would be in , the droopy taco shape , is n't isometric to the original flat pizza . why ? because of math . as the pizza example shows , we can learn a lot by looking at the mathematical properties of different shapes . and it 's especially nice when those shapes happen to be pizza slices .
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translator : andrea mcdonough reviewer : bedirhan cinar pretty much everyone loves eating pizza , but it can be a messy business . pizza is soft and bendable . so how can you stop all that cheese from falling off ?
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chances are you ’ ve never cut a ping-pong ball into pieces . but , if you do , you can see immediately that the thin plastic they ’ re made from is soft and flexible . this is a bit surprising , since ping-pong balls themselves are hard and rigid . thinking about the pizza example , can you explain why this might be ?
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it 's estimated that for every 10,000 bills in the u.s. , one of those bills is fake . that may not sound like much , but it adds up to millions of dollars in cold hard cash . counterfeit money has the potential to cause all sorts of problems , from leaving you short $ 20 to destabilizing national economies . but do n't worry . you can help catch the counterfeits . all you need are some simple tools and a bit of chemistry . first up , the anti-counterfeit detection pen . the pen looks like a highlighter and contains a solution of potassium iodide and elemental iodine . it reveals of the presence of starch , which is commonly used to strengthen regular printer paper , but wo n't be found in real money . that 's because authentic bills are made of cotton and linen and are threaded with tiny red and blue fibers . that material is made by a single , highly-guarded company called crane and company , which has been printing currency since paul revere asked them to help finance the revolutionary war . the starch in many counterfeit bills , on the other hand , is made of two molecules : amylopectin and amylose . it 's amylose that gives the fake away . its long chain of sugar molecules connected by oxygen atoms forms a helical structure , like dna . iodide likes to squeeze inside this coil , forming a new compound that leaves a dark mark on the paper . however , in the absence of starch , there is no chemical reaction and the mark will look light yellow . so if the fake is n't printed on starchy paper , iodine solutions ca n't help you . that 's one of the reasons u.s. bills printed since 1996 have been chemically enhanced to include another counterfeit countermeasure : a strip that fluoresces under uv light . that 's the same kind of light used at black light parties and airport security lines . the polyester strip printed with invisble ink is just one millimeter wide and is found in different positions depending on a bill 's value . if you hold your dollar up to natural light , you can see the amount and the word usa printed on the band . but under uv light , these strips really shine . they contain molecules that can be excited by absorbing certain amounts of energy , specifically , that given off by common uv light sources . as these excited molecules return to their original states , they lose a bit of energy as heat and then radiate the rest as light . energy is inversely related to wavelength , which means that the longer wavelengths have lower energy . so the lower energy light given off by the strip means longer wavelengths that fall in the visible range , and suddenly we can see that which had been invisible . and if a glowing strip does n't show up on a recent bill , you have a fake on your hands . for times when you 're not dealing with counterfeit masterminds , looking for simple visual cues will do . make sure the portrait looks lifelike and not flat , the seal has perfectly even sawtooth points , the inked border is unbroken , and the serial number has precisely equal spacing between each number . so the next time you come across some dubious dough , have a closer look , pull out your iodine solution , or take it to a rave and you just might catch a counterfeit .
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that 's the same kind of light used at black light parties and airport security lines . the polyester strip printed with invisble ink is just one millimeter wide and is found in different positions depending on a bill 's value . if you hold your dollar up to natural light , you can see the amount and the word usa printed on the band .
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the fluorescent ink bands are all different colors on each bill denomination . what does that tell you about the wavelengths that each band emits ?
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translator : tom carter reviewer : bedirhan cinar why are gas stations always built right next to other gas stations ? why can i drive for a mile without finding a coffee shop and then stumble across three on the same corner ? why do grocery stores , auto repair shops and restaurants always seem to exist in groups instead of being spread evenly throughout a community ? while there are several factors that might go into deciding where to place your business , clusters of similar companies can be explained by a very simple story called hotelling 's model of spatial competition . imagine that you sell ice cream at the beach . your beach is one mile long and you have no competition . where would you place your cart in order to sell the most product ? in the middle . the one-half-mile walk may be too far for some people at each end of the beach , but your cart serves as many people as possible . one day you show up at work just as your cousin teddy is arriving at the beach with his own ice cream cart . in fact , he 's selling exactly the same type of ice cream as you are . you agree that you will split the beach in half . in order to ensure that customers do n't have to walk too far you set up your cart a quarter mile south of the beach center , right in the middle of your territory . teddy sets up a quarter mile north of the center , in the middle of teddy territory . with this agreement , everyone south of you buys ice cream from you . everyone north of teddy buys from him , and the 50 % of beachgoers in between walk to the closest cart . no one walks more than a quarter of a mile , and both vendors sell to half of the beachgoers . game theorists consider this a socially optimal solution . it minimizes the maximum number of steps any visitor must take in order to reach an ice cream cart . the next day , when you arrive at work , teddy has set up his cart in the middle of the beach . you return to your location a quarter mile south of center and get the 25 % of customers to the south of you . teddy still gets all of the customers north in teddy territory , but now you split the 25 % of people in between the two carts . day three of the ice cream wars , you get to the beach early , and set up right in the center of teddy territory , assuming you 'll serve the 75 % of beachgoers to your south , leaving your cousin to sell to the 25 % of customers to the north . when teddy arrives , he sets up just south of you stealing all of the southerly customers , and leaving you with a small group of people to the north . not to be outdone , you move 10 paces south of teddy to regain your customers . when you take a mid-day break , teddy shuffles 10 paces south of you , and again , steals back all the customers to the far end of the beach . throughout the course of the day , both of you continue to periodically move south towards the bulk of the ice cream buyers , until both of you eventually end up at the center of the beach , back to back , each serving 50 % of the ice-cream-hungry beachgoers . at this point , you and your competitive cousin have reached what game theorists call a nash equilibrium - the point where neither of you can improve your position by deviating from your current strategy . your original strategy , where you were each a quarter mile from the middle of the beach , did n't last , because it was n't a nash equilibrium . either of you could move your cart towards the other to sell more ice cream . with both of you now in the center of the beach , you ca n't reposition your cart closer to your furthest customers without making your current customers worse off . however , you no longer have a socially optimal solution , since customers at either end of the beach have to walk further than necessary to get a sweet treat . think about all the fast food chains , clothing boutiques , or mobile phone kiosks at the mall . customers may be better served by distributing services throughout a community , but this leaves businesses vulnerable to aggressive competition . in the real world , customers come from more than one direction , and businesses are free to compete with marketing strategies , by differentiating their product line , and with price cuts , but at the heart of their strategy , companies like to keep their competition as close as possible .
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throughout the course of the day , both of you continue to periodically move south towards the bulk of the ice cream buyers , until both of you eventually end up at the center of the beach , back to back , each serving 50 % of the ice-cream-hungry beachgoers . at this point , you and your competitive cousin have reached what game theorists call a nash equilibrium - the point where neither of you can improve your position by deviating from your current strategy . your original strategy , where you were each a quarter mile from the middle of the beach , did n't last , because it was n't a nash equilibrium . either of you could move your cart towards the other to sell more ice cream .
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what is a nash equilibrium ?
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approximately 7 million people around the world die from heart attacks every year , and cardiovascular disease , which causes heart attacks and other problems like strokes , is the world 's leading killer . so what causes a heart attack ? like all muscles , the heart needs oxygen , and during a heart attack , it ca n't get enough . fatty deposits , or plaques , develop on the walls of our coronary arteries . those are the vessels that supply oxygenated blood to the heart . these plaques grow as we age , sometimes getting chunky , hardened , or enflamed . eventually , the plaques can turn into blockages . if one of the plaques ruptures or cracks , a blood clot will form around it in minutes , and a partially closed artery can become completely blocked . blood flow is cut off to the cardiac muscle and the oxygen-starved cells start to die within several minutes . this is a myocardial infarction , or heart attack . things can rapidly deteriorate in the absence of treatment . the injured muscle may not be able to pump blood as well , and its rhythm might be thrown off . in the worst case scenario , a heart attack can cause sudden death . and how do you know that someone is having a heart attack ? the most common symptom is chest pain caused by the oxygen-deprived heart muscle . patients describe it as crushing or vice-like . it can radiate to the left arm , jaw , back , or abdomen . but it 's not always as sudden and dramatic as it is in the movies . some people experience nausea or shortness of breath . symptoms may be less prominent in women and the elderly . for them , weakness and tiredness may be the main signal . and surprisingly , in many people , especially those with diabetes , which affects the nerves that carry pain , a heart attack may be silent . if you think that someone might be having a heart attack , the most important thing is to respond quickly . if you have access to emergency medical services , call them . they 're the fastest way to get to a hospital . taking aspirin , which thins the blood , and nitroglycerin , which opens up the artery , can help keep the heart attack from getting worse . in the emergency room , doctors can diagnose a heart attack . they commonly use an electrocardiogram to measure the heart 's electrical activity and a blood test to assess heart muscle damage . the patient is then taken to a high-tech cardiac suite where tests are done to locate the blockages . cardiologists can reopen the blocked artery by inflating it with a balloon in a procedure called an angioplasty . frequently , they also insert a metal or polymer stent that will hold the artery open . more extensive blockages might require coronary artery bypass surgery . using a piece of vein or artery from another part of the body , heart surgeons can reroute blood flow around the blockage . these procedures reestablish circulation to the cardiac muscle , restoring heart function . heart attack treatment is advancing , but prevention is vital . genetics and lifestyle factors both affect your risk . and the good news is that you can change your lifestyle . exercise , a healthy diet , and weight loss all lower the risk of heart attacks , whether you 've had one before or not . doctors recommend exercising a few times a week , doing both aerobic activity and strength training . a heart-healthy diet is low in sugar and saturated fats , which are both linked to heart disease . so what should you eat ? lots of fiber from vegetables , chicken and fish instead of red meat , whole grains and nuts like walnuts and almonds all seem to be beneficial . a good diet and exercise plan can also keep your weight in a healthy range , which will lower your heart attack risk as well . and of course , medications can also help prevent heart attacks . doctors often prescribe low-dose aspirin , for example , particularly for patients who 've already had a heart attack and for those known to be at high risk . and drugs that help manage risk factors , like high blood pressure , cholesterol , and diabetes , will make heart attacks less likely , too . heart attacks may be common , but they do n't have to be inevitable . a healthy diet , avoiding tobacco use , staying fit , and enjoying plenty of sleep and lots of laughter all go a long way in making sure your body 's most important muscle keeps on beating .
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approximately 7 million people around the world die from heart attacks every year , and cardiovascular disease , which causes heart attacks and other problems like strokes , is the world 's leading killer . so what causes a heart attack ? like all muscles , the heart needs oxygen , and during a heart attack , it ca n't get enough .
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what is the commonest symptom that heralds the onset of a heart attack ?
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meet the nurdles . they may be tiny , look harmless , and sound like a bunch of cartoon characters , but do n't be fooled . these little guys are plotting ocean domination . nurdles are some of the planet 's most pervasive pollutants , found in lakes , rivers , and oceans across the globe . the tiny factory-made pellets form the raw material for every plastic product we use . and each year , billions of pounds of nurdles are produced , melted , and molded into toys , bottles , buttons , bags , pens , shoes , toothbrushes , and beads . they are everywhere . and they come in many guises , multi-colored and many-shaped , they range in size from just a few millimeters to mere specks that are only visible through a microscope . but their real advantage in the quest for ocean domination is their incredible endurance , which allows them to persist in an environment for generations because their artificial makeup makes them unable to biodegrade . so , just as long as they do n't get into the environment , we have nothing to worry about , right ? the problem is nurdles have a crafty way of doing exactly this . produced in several countries and shipped to plastic manufacturing plants the world over , nurdles often escape during the production process , carried by runoff to the coast or during shipping when they 're mistakenly tipped into the waves . once in the water , nurdles are swiftly carried by currents , ultimately winding up in huge circulating ocean systems called gyres , where they convene to plan their tactics . the earth has five gyres that act as gathering points , but the headquarters of nurdle ocean domination are in the pacific ocean , where the comparative enormity of the gyre and the resulting concentration of pollution is so huge that it 's known as the great pacific garbage patch . here , nurdles have good company . this gyre draws in all kinds of pollution , but because they do n't biodegrade , plastics dominate , and they come from other sources besides nurdles , too . you know those tiny beads you see in your face wash or your toothpaste ? they 're often made of plastic , and after you flush them down the drain , some also end up in this giant garbage patch , much to the delight of the nurdles , building up their plastic army there . and then there are the large pieces of unrecycled plastic litter , like bottles and carrier bags , transported by runoff from land to sea . over time , these plastic chunks turn into a kind of nurdle , too , but one that 's been worn down by the elements , not made in a factory . and as if they were n't threatening enough , the rough , pitted surfaces of these microplastics , the name we give to all those collective plastic bits , water-born chemicals stick , or adhere , to them , making them toxic . this gathering has grown so immense that the oceanic garbage patch can shift from around the size of texas to something the size of the united states . but while this toxic tornado is circulating , the birds , fish , filter feeders , whales , and crustaceans around it are just going about their daily business , which means they 're looking for food . unfortunately for them , tiny bits of floating plastic look a lot like fish eggs and other enticing bits of food . but once ingested , microplastics have a very different and terrible habit of sticking around . inside an animal 's stomach , they not only damage its health with a cocktail of toxins they carry but can also lead to starvation because although nurdles may be ingested , they 're never digested , tricking an animal into feeling like it 's continually full and leading to its eventual death . when one organism consumes another , microplastics and their toxins are then passed up through the food chain . and that 's how , bit by bit , nurdles accomplish their goal , growing ever more pervasive as they wipe out marine life and reshape the ocean 's ecosystems . so , how to break this cycle ? the best solution would be to take plastics out of the equation altogether . that 'll take a lot of time but requires only small collective changes , like more recycling , replacing plastics with paper and glass , and ditching that toothpaste with the microbeads . if we accomplish these things , perhaps over time fewer and fewer nurdles will turn up at that giant garbage patch , their army of plastics will grow weaker , and they 'll surrender the ocean to its true keepers once more .
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they are everywhere . and they come in many guises , multi-colored and many-shaped , they range in size from just a few millimeters to mere specks that are only visible through a microscope . but their real advantage in the quest for ocean domination is their incredible endurance , which allows them to persist in an environment for generations because their artificial makeup makes them unable to biodegrade .
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how many major gyres are there in the world ’ s oceans ?
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translator : jessica ruby reviewer : caroline cristal let 's say that it would take you ten minutes to solve this puzzle . how long would it take if you received constant electric shocks to your hands ? longer , right ? because the pain would distract you from the task . well , maybe not ; it depends on how you handle pain . some people are distracted by pain . it takes them longer to complete a task , and they do it less well . other people use tasks to distract themselves from pain , and those people actually do the task faster and better when they 're in pain than when they 're not . some people can just send their mind wandering to distract themselves from pain . how can different people be subjected to the exact same painful stimulus and yet experience the pain so differently ? and why does this matter ? first of all , what is pain ? pain is an unpleasant sensory and emotional experience , associated with actual or potential tissue damage . pain is something we experience , so it 's best measured by what you say it is . pain has an intensity ; you can describe it on a scale from zero , no pain , to ten , the most pain imaginable . but pain also has a character , like sharp , dull , burning , or aching . what exactly creates these perceptions of pain ? well , when you get hurt , special tissue damage-sensing nerve cells , called nociceptors , fire and send signals to the spinal cord and then up to the brain . processing work gets done by cells called neurons and glia . this is your grey matter . and brain superhighways carry information as electrical impulses from one area to another . this is your white matter . the superhighway that carries pain information from the spinal cord to the brain is our sensing pathway that ends in the cortex , a part of the brain that decides what to do with the pain signal . another system of interconnected brain cells called the salience network decides what to pay attention to . since pain can have serious consequences , the pain signal immediately activates the salience network . now , you 're paying attention . the brain also responds to the pain and has to cope with these pain signals . so , motor pathways are activated to take your hand off a hot stove , for example . but modulation networks are also activated that deliver endorphins and enkephalins , chemicals released when you 're in pain or during extreme exercise , creating the runner 's high . these chemical systems help regulate and reduce pain . all these networks and pathways work together to create your pain experience , to prevent further tissue damage , and help you to cope with pain . this system is similar for everyone , but the sensitivity and efficacy of these brain circuits determines how much you feel and cope with pain . this is why some people have greater pain than others and why some develop chronic pain that does not respond to treatment , while others respond well . variability in pain sensitivities is not so different than all kinds of variability in responses to other stimuli . like how some people love roller coasters , but other people suffer from terrible motion sickness . why does it matter that there is variability in our pain brain circuits ? well , there are many treatments for pain , targeting different systems . for mild pain , non-prescription medications can act on cells where the pain signals start . other stronger pain medicines and anesthetics work by reducing the activity in pain-sensing circuits or boosting our coping system , or endorphins . some people can cope with pain using methods that involve distraction , relaxation , meditation , yoga , or strategies that can be taught , like cognitive behavioral therapy . for some people who suffer from severe chronic pain , that is pain that does n't go away months after their injury should have healed , none of the regular treatments work . traditionally , medical science has been about testing treatments on large groups to determine what would help a majority of patients . but this has usually left out some who did n't benefit from the treatment or experienced side effects . now , new treatments that directly stimulate or block certain pain-sensing attention or modulation networks are being developed , along with ways to tailor them to individual patients , using tools like magnetic resonance imaging to map brain pathways . figuring out how your brain responds to pain is the key to finding the best treatment for you . that 's true personalized medicine .
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why does it matter that there is variability in our pain brain circuits ? well , there are many treatments for pain , targeting different systems . for mild pain , non-prescription medications can act on cells where the pain signals start . other stronger pain medicines and anesthetics work by reducing the activity in pain-sensing circuits or boosting our coping system , or endorphins . some people can cope with pain using methods that involve distraction , relaxation , meditation , yoga , or strategies that can be taught , like cognitive behavioral therapy .
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your pain experience and coping ________ .
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denis diderot left a dungeon outside paris on november 3 , 1749 . he 'd had his writing burned in public before , but this time , he 'd gotten locked up under royal order for an essay about a philosopher 's death bed rejection of god . to free himself , denis promised never to write things like that again . so he got back to work on something a little like that , only way worse , and much bigger . in 1745 , publisher andré le breton had hired diderot to adapt the english cyclopedia , or a universal dictionary of arts and sciences for french subscribers . a broke writer , diderot survived by translating , tutoring , and authoring sermons for priests , and a pornographic novel once . le breton paired him with co-editor jean le rond d'alembert , a math genius found on a church doorstep as a baby . technical dictionaries , like the cyclopedia , were n't new , but no one had attempted one publication covering all knowledge , so they did . the two men organized the french enlightenment 's brightest stars to produce the first encyclopedia , or rational dictionary of the arts , sciences , and crafts . assembling every essential fact and principle in , as it turned out , over 70,000 entries , 20,000,000 words in 35 volumes of text and illustrations created over three decades of researching , writing , arguging , smuggling , backstabbing , law-breaking , and alphabetizing . to organize the work , diderot adapted francis bacon 's `` classification of knowledge '' into a three-part system based on the mind 's approaches to reality : memory , reason , and imagination . he also emphasized the importance of commerce , technology , and crafts , poking around shops to study the tools and techniques of parisian laborers . to spotlight a few of the nearly 150 philosoph contributers , jean jacques rousseau , diderot 's close friend , wrote much of the music section in three months , and was never reimbursed for copy fees . his entry on political economy holds ideas he 'd later develop further in `` the social contract . '' d'alembert wrote the famous preliminary discourse , a key statement of the french enlightenment , championing independent investigative reasoning as the path to progress . louis de jaucourt wrote a quarter of the encyclopedia , 18,000 articles , 5,000,000 words , unpaid . louis once spent 20 years writing a book on anatomy , shipped it to amsterdam to be published uncensored , and the ship sank . voltaire contributed entries , among them history , elegance , and fire . diderot 's entries sometimes exhibit slight bias . in `` political authority , '' he dismantled the divine right of kings . under `` citizen , '' he argued a state was strongest without great disparity in wealth . not surprising from the guy who wrote poetry about mankind strangling its kings with the entrails of a priest . so diderot 's masterpiece was n't a hit with the king or highest priest . upon release of the first two volumes , louie xv banned the whole thing but enjoyed his own copy . pope clement xiii ordered it burned . it was `` dangerous , '' `` reprehensible , '' as well as `` written in french , '' and in `` the most seductive style . '' he declared readers excommunicated and wanted diderot arrested on sight . but diderot kept a step ahead of being shut down , smuggling proofs outside france for publication , and getting help from allies in the french regime , including the king 's mistress , madame de pompadour , and the royal librarian and censor , malesherbes , who tipped diderot off to impending raids , and even hid diderot 's papers at his dad 's house . still , he faced years of difficulty . d'alembert dropped out . rousseau broke off his friendship over a line in a play . worse yet , his publisher secretly edited some proofs to read less radically . the uncensored pages reappeared in russia in 1933 , long after diderot had considered the work finished and died at lunch . the encyclopedia he left behind is many things : a cornerstone of the enlightenment , a testament to france 's crisis of authority , evidence of popular opinions migration from pulpit and pew to cafe , salon , and press . it even has recipes . it 's also irrepressibly human , as you can tell from diderot 's entry about a plant named aguaxima . read it yourself , preferably out loud in a french accent .
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but diderot kept a step ahead of being shut down , smuggling proofs outside france for publication , and getting help from allies in the french regime , including the king 's mistress , madame de pompadour , and the royal librarian and censor , malesherbes , who tipped diderot off to impending raids , and even hid diderot 's papers at his dad 's house . still , he faced years of difficulty . d'alembert dropped out .
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today , some fields and industries have entire bodies of knowledge that recycle every couple years or faster . if you had to spend thirty years on one reference work starting today , what topics would you focus on ?
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translator : tom carter reviewer : bedirhan cinar she 's only a few feet away . the closer he gets , the more nervous he becomes , the budding zit on his nose growing bigger and bigger until it practically eclipses his face . she looks at him hovering nearby , sees the massive zit , and giggles . he slumps away , feeling sick . stress can sure make a mess , and it happens to both teens and adults . but how does it happen ? let 's rewind to before the zit , to before justin even sees his crush . already late for school , justin got to class just in time to hear the teacher say `` pop quiz . '' he had n't done his homework the night before , and felt more unprepared than the ambushed world war ii soldiers he was supposed to write about . a sudden rush of panic swept over his body , leaving him with sweaty palms , a foggy mind and a racing heart . he stumbled out of class in a daze , and ran straight into his all-time crush , spiking up his stress . stress is a general biological response to a potential danger . in primitive caveman terms , stress can make you fight for your life , or run for your life , if , for example , you 're confronted by a hungry saber-tooth tiger . special chemicals called stress hormones run through your body , giving you more oxygen and power to run away from danger or to face it and fight for your life , hence the term `` fight or flight . '' but when you do n't fight , or take flight , you face the plight . when we 're taking final exams , sitting in traffic or pondering pollution , we internalize stress . it all begins in the brain . the hypothalamus , the master controller of your hormones , releases something called corticotropin-releasing hormone . this triggers the pituitary gland , a pea-sized gland found at the base of the brain , to release adrenocorticotropic hormone which then stimulates the adrenal gland sitting on top of the kidneys to release cortisol , the major stress hormone . these natural chemicals are a great help when you need to run away quickly , or do superhuman feats of courage , but when you 're simply sitting , these stress hormones collect in the body and affect your overall health . stress hormones increase inflammation in the body , suppress the immune system , which makes you more susceptible to infection by acne-causing bacteria , and can even increase oil production in the skin . and this is the perfect storm for forming a pimple . cortisol is a major stress hormone involved in making skin cells churn out oily lipids from special glands called sebaceous glands . but when there 's too much of these oily lipids , called sebum , they can plug up the swollen , inflamed pores and trap the pesky , acne-causing bacteria inside , where they set up house and thrive . add a dash of inflammatory neuropeptides released by the nervous system when you 're -- well , nervous -- and angry zits follow . to make matters worse , justin is a boy , meaning he 's got more testosterone than girls . testosterone is another hormone that increases oil production in the skin . so , his already oily skin , together with a boost in oil and inflammation from stress , is the perfect environment for bacteria to swell , swell , swell up into a major zit . so what could 've justin done to avoid the big pimple ? stressful situations are unavoidable . but we can try to change our responses so that we 're not so stressed in the end . and had he been confident in approaching her , she might not have noticed the pimple , or he might not have had one .
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this triggers the pituitary gland , a pea-sized gland found at the base of the brain , to release adrenocorticotropic hormone which then stimulates the adrenal gland sitting on top of the kidneys to release cortisol , the major stress hormone . these natural chemicals are a great help when you need to run away quickly , or do superhuman feats of courage , but when you 're simply sitting , these stress hormones collect in the body and affect your overall health . stress hormones increase inflammation in the body , suppress the immune system , which makes you more susceptible to infection by acne-causing bacteria , and can even increase oil production in the skin .
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you just heard that if ‘ you don ’ t fight or take flight , you face the plight. ’ describe how you think constant activation of stress hormones in the body , also known as chronic stress , is detrimental to our health . ( video hint : “ these natural chemicals are a great help… ” )
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in the summer of 1963 , a high school teacher changed the way the world looked at `` the wizard of oz . '' his name was henry littlefield , and he was teaching an american history class . he 'd made it to the late 19th century , a time called the gilded age , but he was struggling to keep his class interested in the complex social and economic issues of the time . then one night , while he was reading `` the wonderful wizard of oz '' to his daughters , he had an idea . in the 1890s , farmers wanted to add silver to the gold standard to put more money in circulation and make it easier for farmers to borrow . in the book , dorothy walked to the emerald city on the yellow brick road in her silver shoes . the movie 's ruby red slippers started out as silver . silver and gold on the road to prosperity . l. frank baum had published the book in 1900 at the height of the gilded age , and the analogy did n't seem out of the question . no one else had seen these connections , but that did n't deter littlefield . he taught his class about the gilded age using the book , and soon he and his students were finding more connections . for instance , in the late 1890s , the u.s. had recently recovered from the civil war and integrated vast new territories , bringing an era of prosperity for some . but while industry and finance in the north and east prospered , farmers across the south and midwest struggled . this led to the populist movement , uniting farmers and workers against urban elites . by 1896 , the movement had grown into the people 's party , and its support of democrat williams jennings bryan put him in reach of the presidency . meanwhile in oz , claimed littlefield , dorothy is a typical american girl whose hard life in kansas is literally turned upside down by powerful forces outside her control . the munchkins are the common people oppressed by the witch of the east , banks and monopolies . the scarecrow is the farmer , considered naive but actually quite resourceful , the tin woodman is the industrial worker dehumanized by factory labor , and the cowardly lion is william jennings bryan who could be an influential figure if only he were brave enough to adopt the populist 's radical program . together , they travel along a golden yellow road towards a grand city whose ruler 's power turns out to be built on illusions . littlefield published some of these observations in an essay . his claim that this fantasy was actually a subversive critique of american capitalism appealed to many people in 1960s . other scholars took up the theme , and the proposed analogies and connections multiplied . they suggested that dorothy 's dog toto represented the teetotalers of the prohibition party . oz was clearly the abbreviation for ounces , an important unit in the silver debate . the list goes on . by the 1980s , this understanding of the book was accepted so widely that several american history textbooks mentioned it in discussions of late 19th century politics . but is the theory right ? l. frank baum 's introduction claims the book is just an innocent children 's story . could he have been deliberately throwing people off the trail ? and is it fair to second guess him so many decades later ? there 's no definitive answer , which is part of why authorial intent is a complex , tangled , fun question to unravel . and some recent scholars have interpreted `` the wonderful wizard of oz '' in the opposite way as littlefield . they claim it 's a celebration of the new urban consumer culture . historian william leach argued that the dazzling emerald city of oz was meant to acclimate people to the shiny , new america . in the end , all we know for sure is that baum , inspired by european folk legends , had set out to create one for american children . and whether or not he intended any hidden meanings , its continuing relevance suggests he succeeded in creating a fairytale america can call its own .
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there 's no definitive answer , which is part of why authorial intent is a complex , tangled , fun question to unravel . and some recent scholars have interpreted `` the wonderful wizard of oz '' in the opposite way as littlefield . they claim it 's a celebration of the new urban consumer culture .
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the author of `` the wonderful wizard of oz '' was :
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there are a lot of ways this marvelous language of ours , english , does n't make sense . for example , most of the time when we talk about more than one of something , we put an s on the end . one cat , two cats . but then , there 's that handful of words where things work differently . alone you have a man ; if he has company , then you 've got men , or probably better for him , women too . although if there were only one of them , it would be a woman . or if there 's more than one goose , they 're geese , but why not lots of mooses , meese ? or if you have two feet , then why do n't you read two beek instead of books . the fact is that if you were speaking english before about a thousand years ago , beek is exactly what you would have said for more than one book . if modern english is strange , old english needed therapy . believe it or not , english used to be an even harder language to learn than it is today . twenty-five hundred years ago , english and german were the same language . they drifted apart slowly , little by little becoming more and more different . that meant that in early english , just like in german , inanimate objects had gender . a fork , gafol , was a woman ; a spoon , laefel , was a man ; and the table they were on , bord , was neither , also called neuter . go figure ! being able to use words meant not just knowing their meaning but what gender they were , too . and while today there are only about a dozen plurals that do n't make sense , like men and geese , in old english , it was perfectly normal for countless plurals to be like that . you think it 's odd that more than one goose is geese ? well , imagine if more than one goat was a bunch of gat , or if more than one oak tree was a field of ack . to be able to talk about any of these , you just had to know the exact word for their plural rather than just adding the handy s on the end . and it was n't always an s at the end either . in merry old english , they could add other sounds to the end . just like more than one child is children , more than one lamb was lambru , you fried up your eggru , and people talked not about breads , but breadru . sometimes it was like sheep is today - where , to make a plural , you do n't do anything . one sheep , two sheep . in old english , one house , two house . and just like today , we have oxen instead of oxes . old english people had toungen instead of tongues , namen instead of names , and if things stayed the way they were , today we would have eyen instead of eyes . so , why did n't things stay the way they were ? in a word , vikings . in the 8th century , scandinavian marauders started taking over much of england . they did n't speak english , they spoke norse . plus , they were grown-ups , and grown-ups are n't as good at learning languages as children . after the age of roughly 15 , it 's almost impossible to learn a new language without an accent and without slipping up here and there as we all know from what language classes are like . the vikings were no different , so they had a way of smoothing away the harder parts of how english worked . part of that was those crazy plurals . imagine running up against a language with eggru and gat on the one hand , and then with other words , all you have to do is add 's ' and get days and stones . would n't it make things easier to just use the 's ' for everything ? that 's how the vikings felt too . and there were so many of them , and they married so many of the english women , that pretty soon , if you grew up in england , you heard streamlined english as much as the real kind . after a while nobody remembered the real kind any more . nobody remembered that once you said doora instead of doors and handa instead of hands . plurals made a lot more sense now , except for a few hold-outs like children and teeth that get used so much that it was hard to break the habit . the lesson is that english makes a lot more sense than you think . thank the ancestors of people in copenhagen and oslo for the fact that today we do n't ask for a handful of pea-night instead of peanuts . although , would n't it be fun , if for just a week or two , we could ?
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the fact is that if you were speaking english before about a thousand years ago , beek is exactly what you would have said for more than one book . if modern english is strange , old english needed therapy . believe it or not , english used to be an even harder language to learn than it is today .
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what do modern english speakers do to words when they want to talk about more than one of something ?
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on july 26 , 1943 , los angeles was blanketed by a thick gas that stung people 's eyes and blocked out the sun . panicked residents believed their city had been attacked using chemical warfare . but the cloud was n't an act of war . it was smog . a portmanteau of smoke and fog , the word smog was coined at the beginning of the 20th century to describe the thick gray haze that covered cities such as london , glasgow , and edinburgh . this industrial smog was known to form when smoke from coal-burning home stoves and factories combined with moisture in the air . but the smog behind the la panic was different . it was yellowish with a chemical odor . since the city did n't burn much coal , its cause would remain a mystery until a chemist named arie haagen-smit identified two culprits , volatile organic compounds , or vocs , and nitrous oxides . vocs are compounds that easily become vapors and may contain elements , such as carbon , oxygen , hydrogen , chlorine , and sulfur . some are naturally produced by plants and animals , but others come from manmade sources , like solvents , paints , glues , and petroleum . meanwhile , the incomplete combustion of gas in motor vehicles releases nitrous oxide . that 's what gives this type of smog its yellowish color . vocs and nitrous oxide react with sunlight to produce secondary pollutants called pans and tropospheric , or ground level , ozone . pans and ozone cause eye irritation and damage lung tissue . both are key ingredients in photochemical smog , which is what had been plaguing la . so why does smog affect some cities but not others ? both industrial and photochemical smog combine manmade pollution with local weather and geography . london 's high humidity made it a prime location for industrial smog . photochemical smog is strongest in urban areas with calm winds and dry , warm , sunny weather . the ultraviolet radiation from sunlight provides the energy necessary to breakdown molecules that contribute to smog formation . cities surrounded by mountains , like la , or lying in a basin , like beijing , are also especially vulnerable to smog since there 's nowhere for it to dissipate . that 's also partially due to a phenomenon known as temperature inversion , where instead of warm air continuously rising upward , a pollution-filled layer of air remains trapped near the earth 's surface by a slightly warmer layer above . smog is n't just an aesthetic eyesore . both forms of smog irritate the eyes , nose , and throat , exacerbate conditions like asthma and emphysema , and increase the risk of respiratory infections like bronchitis . smog can be especially harmful to young children and older people and exposure in pregnant women has been linked to low birth weight and potential birth defects . secondary pollutants found in photochemical smog can damage and weaken crops and decrease yield , making them more susceptible to insects . yet for decades , smog was seen as the inevitable price of civilization . londoners had become accustomed to the notorious pea soup fog swirling over their streets until 1952 , when the great smog of london shut down all transportation in the city for days and caused more than 4,000 respiratory deaths . as a result , the clean air act of 1956 banned burning coal in certain areas of the city , leading to a massive reduction in smog . similarly , regulations on vehicle emissions and gas content in the us reduced the volatile compounds in the air and smog levels along with them . smog remains a major problem around the world . countries like china and poland that depend on coal for energy experience high levels of industrial smog . photochemical smog and airborne particles from vehicle emissions affect many rapidly developing cities , from mexico city and santiago to new delhi and tehran . governments have tried many methods to tackle it , such as banning cars from driving for days at a time . as more than half of the world 's population crowds into cities , considering a shift to mass transit and away from fossil fuels may allow us to breathe easier .
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a portmanteau of smoke and fog , the word smog was coined at the beginning of the 20th century to describe the thick gray haze that covered cities such as london , glasgow , and edinburgh . this industrial smog was known to form when smoke from coal-burning home stoves and factories combined with moisture in the air . but the smog behind the la panic was different .
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the burning of which fuel is the main source of industrial smog ?
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consider the classic white t-shirt . annually , we sell and buy two billion t-shirts globally , making it one of the most common garments in the world . but how and where is the average t-shirt made , and what 's its environmental impact ? clothing items can vary a lot , but a typical t-shirt begins its life on a farm in america , china , or india where cotton seeds are sown , irrigated and grown for the fluffy bolls they produce . self-driving machines carefully harvest these puffs , an industrial cotton gin mechanically separates the fluffy bolls from the seeds , and the cotton lint is pressed into 225-kilogram bales . the cotton plants require a huge quantity of water and pesticides . 2,700 liters of water are needed to produce the average t-shirt , enough to fill more than 30 bathtubs . meanwhile , cotton uses more insecticides and pesticides than any other crop in the world . these pollutants can be carcinogenic , harm the health of field workers , and damage surrounding ecosystems . some t-shirts are made of organic cotton grown without pesticides and insecticides , but organic cotton makes up less than 1 % of the 22.7 million metric tons of cotton produced worldwide . once the cotton bales leave the farm , textile mills ship them to a spinning facility , usually in china or india , where high-tech machines blend , card , comb , pull , stretch , and , finally , twist the cotton into snowy ropes of yarn called slivers . then , yarns are sent to the mill , where huge circular knitting machines weave them into sheets of rough grayish fabric treated with heat and chemicals until they turn soft and white . here , the fabric is dipped into commercial bleaches and azo dyes , which make up the vivid coloring in about 70 % of textiles . unfortunately , some of these contain cancer-causing cadmium , lead , chromium , and mercury . other harmful compounds and chemicals can cause widespread contamination when released as toxic waste water in rivers and oceans . technologies are now so advanced in some countries that the entire process of growing and producing fabric barely touches a human hand . but only up until this point . after the finished cloth travels to factories , often in bangladesh , china , india , or turkey , human labor is still required to stitch them up into t-shirts , intricate work that machines just ca n't do . this process has its own problems . bangladesh , for example , which has surpassed china as the world 's biggest exporter of cotton t-shirts , employs 4.5 million people in the t-shirt industry , but they typically face poor conditions and low wages . after manufacture , all those t-shirts travel by ship , train , and truck to be sold in high-income countries , a process that gives cotton an enormous carbon footprint . some countries produce their own clothing domestically , which cuts out this polluting stage , but generally , apparel production accounts for 10 % of global carbon emissions . and it 's escalating . cheaper garments and the public 's willingness to buy boosted global production from 1994 to 2014 by 400 % to around 80 billion garments each year . finally , in a consumer 's home , the t-shirt goes through one of the most resource-intensive phases of its lifetime . in america , for instance , the average household does nearly 400 loads of laundry per year each using about 40 gallons of water . washing machines and dryers both use energy , with dryers requiring five to six times more than washers . this dramatic shift in clothing consumption over the last 20 years , driven by large corporations and the trend of fast fashion has cost the environment , the health of farmers , and driven questionable human labor practices . it 's also turned fashion into the second largest polluter in the world after oil . but there are things we can do . consider shopping secondhand . try to look for textiles made from recycled or organic fabrics . wash clothes less and line dry to save resources . instead of throwing them away at the end of their life , donate , recycle , or reuse them as cleaning rags . and , finally , you might ask yourself , how many t-shirts and articles of clothing will you consume over your lifetime , and what will be their combined impact on the world ?
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finally , in a consumer 's home , the t-shirt goes through one of the most resource-intensive phases of its lifetime . in america , for instance , the average household does nearly 400 loads of laundry per year each using about 40 gallons of water . washing machines and dryers both use energy , with dryers requiring five to six times more than washers .
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if you decreased the amount of laundry loads in your household to 100 less than the average , how much water would you save per year ?
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water is the liquid of life . we drink it , we bathe in it , we farm , cook , and clean with it . it 's the most abundant molecule in our bodies . in fact , every life form we know of would die without it . but most importantly , without water , we would n't have iced tea . mmmm , iced tea . why do these ice cubes float ? if these were cubes of solid argon in a cup of liquid argon , they would sink . and the same goes for most other substances . but solid water , a.k.a . ice , is somehow less dense than liquid water . how 's that possible ? you already know that every water molecule is made up of two hydrogen atoms bonded to one oxygen atom . let 's look at a few of the molecules in a drop of water , and let 's say the temperature is 25 degrees celcius . the molecules are bending , stretching , spinning , and moving through space . now , let 's lower the temperature , which will reduce the amount of kinetic energy each of these molecules has so they 'll bend , stretch , spin , and move less . and that means that on average , they 'll take up less space . now , you 'd think that as the liquid water starts to freeze , the molecules would just pack together more and more closely , but that 's not what happens . water has a special kind of interaction between molecules that most other substances do n't have , and it 's called a hydrogen bond . now , remember that in a covalent bond two electrons are shared , usually unequally , between atoms . in a hydrogen bond , a hydrogen atom is shared , also unequally , between atoms . one hydrogen bond looks like this . two look like this . here 's three and four and five , six , seven , eight , nine , ten , eleven , twelve , i could go on . in a single drop of water , hydrogen bonds form extended networks between hundreds , thousands , millions , billions , trillions of molecules , and these bonds are constantly breaking and reforming . now , back to our water as it cools down . above 4 degrees celcius , the kinetic energy of the water molecules keeps their interactions with each other short . hydrogen bonds form and break like high school relationships , that is to say , quickly . but below 4 degrees , the kinetic energy of the water molecules starts to fall below the energy of the hydrogen bonds . so , hydrogen bonds form much more frequently than they break and beautiful structures start to emerge from the chaos . this is what solid water , ice , looks like on the molecular level . notice that the ordered , hexagonal structure is less dense than the disordered structure of liquid water . and you know that if an object is less dense than the fluid it 's in , it will float . so , ice floats on water , so what ? well , let 's consider a world without floating ice . the coldest part of the ocean would be the pitch-black ocean floor , once frozen , always frozen . forget lobster rolls since crustaceans would lose their habitats , or sushi since kelp forests would n't grow . what would canadian kids do in winter without pond hockey or ice fishing ? and forget james cameron 's oscar because the titanic totally would have made it . say goodbye to the white polar ice caps reflecting sunlight that would otherwise bake the planet . in fact , forget the oceans as we know them , which at over 70 % of the earth 's surface area , regulate the atmosphere of the whole planet . but worst of all , there would be no iced tea . mmmmm , iced tea .
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notice that the ordered , hexagonal structure is less dense than the disordered structure of liquid water . and you know that if an object is less dense than the fluid it 's in , it will float . so , ice floats on water , so what ? well , let 's consider a world without floating ice . the coldest part of the ocean would be the pitch-black ocean floor , once frozen , always frozen .
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at 2:44 , we show a boat floating in water and a hot-air balloon floating in air . and you know that if an object is less dense than the fluid it ’ s in , it floats . but a boat is made of steel , and a balloon is made of fabric , both of which are denser than air . how is it that both these objects float ?
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despite advances in medicine , cancer remains one of the most frightening diagnoses patients can receive . what makes it so difficult to cure is that it 's not one illness , but a family of over 100 diseases occurring in different types of cells . and one type of cancer has the unfortunate distinction of afflicting children more than any other type . this is leukemia , a cancer that begins in stem cells found in the bone marrow . a stem cell is a bit like an infant , undeveloped but possessing great potential . many stem cells specialize and become cells of organs , like the liver , brain and heart . but in some tissues , they can continue to divide into new stem cells throughout development , and into adulthood in order to frequently generate new cells and keep up with the body 's needs . one example is the bone marrow , where stem cells differentiate into many types of blood cells . that includes red blood cells , which carry oxygen from the lungs to all tissues , platelets , which help stop bleeding by sticking to damaged blood vessels , and white blood cells , which patrol the body , destroying potentially harmful invaders . every once in a while , something goes wrong during a stem cell 's specialization process and harmful mutations occur in the cell 's dna . cells with compromised dna are supposed to self-destruct , but some damaged cells ignore this order , replicating uncontrollably , even as they lose their original function . these are what we know as cancer cells . it is not yet clear why leukemia is the most common childhood cancer , but one contributing factor may be that leukemias are often caused by just one or two dna modifications , while most cancers require many of them , allowing leukemias to arise faster than other types of cancer . moreover , some dna alterations can occur in white blood cells during fetal development , further increasing the risk of early leukemia . but though it affects more children than any other cancer , adults constitute the majority of leukemia patients overall . once leukemia strikes , the damaged cells reproduce in the blood and the bone marrow until they take up all available space and resources . when the bone marrow can no longer produce the required amount of functional cells , the blood becomes depleted . the lack of red blood cells means that muscles do n't get enough oxygen , the reduced number of platelets is not sufficient to repair wounds , and the dearth of functional white blood cells impairs the immune system , increasing the risk of infections . to restore the normal function of the blood , leukemic cells have to be eliminated . but because leukemias are not solid tumors , they ca n't be removed surgically . instead , the cells are killed inside the body using various treatments that include chemotherapy , a combination of drugs that destroys quickly multiplying cells . unfortunately , this has the side effect of killing healthy cells , such as those found in hair follicles or intestines . and in some cases , the dosage required is so high that it kills all cells in the bone marrow , including stem cells . when this happens , the body is no longer able to create new blood cells on its own . fortunately , outside help can come in the form of stem cells from the bone marrow of a donor . once transplanted into the patient , they rapidly repopulate the bone marrow and the blood . however , bone marrow transplants are a complicated process requiring antigen compatibility between the donor and recipient to keep the transplanted cells from from attacking the patient 's own cells as foreign bodies . unlike with blood transplants , there are thousands of hla types , and even siblings and close relatives may not have compatible bone marrow . if this is the case , the search is expanded to a database containing the genetic makeup of millions of voluntary bone marrow donors . the more potential donors there are , the more patients lives can be saved through successful transplants . leukemia may be a frightening disease , but there is strength and hope in numbers .
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the more potential donors there are , the more patients lives can be saved through successful transplants . leukemia may be a frightening disease , but there is strength and hope in numbers .
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how does leukemia affect the body ?
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there 's a job out there with a great deal of power , pay , prestige , and near-perfect job security . and there 's only one way to be hired : get appointed to the us supreme court . if you want to become a justice on the supreme court , the highest federal court in the united states , three things have to happen . you have to be nominated by the president of the united states , your nomination needs to be approved by the senate , and finally , the president must formally appoint you to the court . because the constitution does n't specify any qualifications , in other words , that there 's no age , education , profession , or even native-born citizenship requirement , a president can nominate any individual to serve . so far , six justices have been foreign-born , at least one never graduated from high school , and another was only 32 years old when he joined the bench . most presidents nominate individuals who broadly share their ideological view , so a president with a liberal ideology will tend to appoint liberals to the court . of course , a justice 's leanings are not always so predictable . for example , when president eisenhower , a republican , nominated earl warren for chief justice , eisenhower expected him to make conservative decisions . instead , warren 's judgements have gone down as some of the most liberal in the court 's history . eisenhower later remarked on that appointment as `` the biggest damned-fool mistake '' he ever made . many other factors come up for consideration , as well , including experience , personal loyalties , ethnicity , and gender . the candidates are then thoroughly vetted down to their tax records and payments to domestic help . once the president interviews the candidate and makes a formal nomination announcement , the senate leadership traditionally turns the nomination over to hearings by the senate judiciary committee . depending on the contentiousness of the choice , that can stretch over many days . since the nixon administration , these hearings have averaged 60 days . the nominee is interviewed about their law record , if applicable , and where they stand on key issues to discern how they might vote . and especially in more recent history , the committee tries to unearth any dark secrets or past indiscretions . the judiciary committee votes to send the nomination to the full senate with a positive or negative recommendation , often reflective of political leanings , or no recommendation at all . most rejections have happened when the senate majority has been a different political party than the president . when the senate does approve , it 's by a simple majority vote , with ties broken by the vice president . with the senate 's consent , the president issues a written appointment , allowing the nominee to complete the final steps to take the constitutional and judicial oaths . in doing so , they solemnly swear to administer justice without respect to persons and do equal right to the poor and the rich and faithfully and impartially discharge and perform all the duties incumbent upon a us supreme court justice . this job is for life , barring resignation , retirement , or removal from the court by impeachment . and of the 112 justices who have held the position , not one has yet been removed from office as a result of an impeachment . one of their roles is to protect the fundamental rights of all americans , even as different parties take power . with the tremendous impact of this responsibility , it 's no wonder that a us supreme court justice is expected to be , in the words of irving r. kaufman , `` a paragon of virtue , an intellectual titan , and an administrative wizard . '' of course , not every member of the court turns out to be an exemplar of justice . each leaves behind a legacy of decisions and opinions to be debated and dissected by the ultimate judges , time and history .
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there 's a job out there with a great deal of power , pay , prestige , and near-perfect job security . and there 's only one way to be hired : get appointed to the us supreme court . if you want to become a justice on the supreme court , the highest federal court in the united states , three things have to happen .
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should the us constitution be amended to limit the number of years a us supreme court justice can serve ? today , us supreme court justices can serve for life . do you agree with this ?
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as far as we know , medieval england was never invaded by ice zombies , or terrorized by dragons , but it was shaken by a power struggle between two noble families spanning generations and involving a massive cast of characters with complex motives and shifting loyalties . if that sounds familiar , it 's because the historical conflicts known as the wars of the roses served as the basis for much of the drama in game of thrones . the real-life seeds of war were sewn by the death of king edward iii in 1377 . edward 's oldest son had died before his father , but his ten-year-old son , richard ii , succeeded to the throne ahead of edward 's three surviving sons . this skipping of an entire generation left lingering claims to the throne among their various offspring , particularly the lancasters , descended from edward 's third son , and the yorks , descended from his fourth son . the name of the ensuing wars comes from the symbols associated with the two families , the white rose of york and the red rose of lancaster . the lancasters first gained the throne when richard ii was deposed by his cousin henry iv in 1399 . despite sporadic unrest , their reign remained secure until 1422 , when henry v 's death in a military campaign left an infant henry vi as king . weak-willed and dominated by advisors , henry was eventually convinced to marry margaret of anjou to gain french support . margaret was beautiful , ambitious , and ruthless in persecuting any threat to her power , and she distrusted richard of york , most of all . york had been the king 's close advisor and loyal general , but was increasingly sidelined by the queen , who promoted her favorite supporters , like the earls of suffolk and somerset . york 's criticism of their inept handling of the war against france led to his exclusion from court and transfer to ireland . meanwhile , mounting military failures , and corrupt rule by margaret and her allies caused widespread discontent , and in the midst of this chaos , richard of york returned with an army to arrest somerset and reform the court . initially unsuccessful , he soon got his chance when he was appointed protector of the realm after henry suffered a mental breakdown . however , less than a year later , henry suddendly recovered and the queen convinced him to reverse york 's reforms . york fled and raised an army once more . though he was unable to directly seize the throne , he managed to be reinstated as protector and have himself and his heirs designated to succeed henry . but instead of a crown , york 's head acquired a pike after he was killed in battle with the queen 's loyalists . his young son took up the claim and was crowned edward iv . edward enjoyed great military success against the lancasters . henry was captured , while margaret fled into exile with their reportedly cruel son , edward of westminster . but the newly crowned king made a tragic political mistake by backing out of his arranged marriage with a french princess to secretly marry the widow of a minor noble . this alienated his most powerful ally , the earl of warwick . warwick allied with the lancasters , turned edward 's jealous younger brother , george , against him , and even briefly managed to restore henry as king , but it did n't last . edward recaptured the throne , the lancaster prince was killed in battle , and henry himself died in captivity not long after . the rest of edward iv 's reign was peaceful , but upon his death in 1483 , the bloodshed resumed . though his twelve-year-old son was due to succeed him , edward 's younger brother richard iii declared his nephews illegitimate due to their father 's secret marriage . he assumed the regency himself and threw the boys in prison . though no one knows what ultimately became of them , after a while , the princes disappeared and richard 's power seemed secure . but his downfall would come only two years later from across the narrow sea of the english channel . henry tudor was a direct descendant of the first duke of lancaster , raised in exile after his father 's death in a previous rebellion . with richard iii 's power grab causing a split in the york faction , henry won support for his royal claim . raising an army in france , he crossed the channel in 1485 and quickly defeated richard 's forces . and by marrying elizabeth of york , elder sister of the disappeared princes , the newly crowned henry vii joined the two roses , finally ending nearly a century of war . we often think of historical wars as decisive conflicts with clearly defined winners and losers . but the wars of the roses , like the fiction they inspired , show us that victories can be uncertain , alliances unstable , and even the power of kings as fleeting as the seasons .
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henry tudor was a direct descendant of the first duke of lancaster , raised in exile after his father 's death in a previous rebellion . with richard iii 's power grab causing a split in the york faction , henry won support for his royal claim . raising an army in france , he crossed the channel in 1485 and quickly defeated richard 's forces .
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why was richard of york named lord protector ?
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in the 1920 's , the german mathematician david hilbert devised a famous thought experiment to show us just how hard it is to wrap our minds around the concept of infinity . imagine a hotel with an infinite number of rooms and a very hardworking night manager . one night , the infinite hotel is completely full , totally booked up with an infinite number of guests . a man walks into the hotel and asks for a room . rather than turn him down , the night manager decides to make room for him . how ? easy , he asks the guest in room number 1 to move to room 2 , the guest in room 2 to move to room 3 , and so on . every guest moves from room number `` n '' to room number `` n+1 '' . since there are an infinite number of rooms , there is a new room for each existing guest . this leaves room 1 open for the new customer . the process can be repeated for any finite number of new guests . if , say , a tour bus unloads 40 new people looking for rooms , then every existing guest just moves from room number `` n '' to room number `` n+40 '' , thus , opening up the first 40 rooms . but now an infinitely large bus with a countably infinite number of passengers pulls up to rent rooms . countably infinite is the key . now , the infinite bus of infinite passengers perplexes the night manager at first , but he realizes there 's a way to place each new person . he asks the guest in room 1 to move to room 2 . he then asks the guest in room 2 to move to room 4 , the guest in room 3 to move to room 6 , and so on . each current guest moves from room number `` n '' to room number `` 2n '' -- filling up only the infinite even-numbered rooms . by doing this , he has now emptied all of the infinitely many odd-numbered rooms , which are then taken by the people filing off the infinite bus . everyone 's happy and the hotel 's business is booming more than ever . well , actually , it is booming exactly the same amount as ever , banking an infinite number of dollars a night . word spreads about this incredible hotel . people pour in from far and wide . one night , the unthinkable happens . the night manager looks outside and sees an infinite line of infinitely large buses , each with a countably infinite number of passengers . what can he do ? if he can not find rooms for them , the hotel will lose out on an infinite amount of money , and he will surely lose his job . luckily , he remembers that around the year 300 b.c.e. , euclid proved that there is an infinite quantity of prime numbers . so , to accomplish this seemingly impossible task of finding infinite beds for infinite buses of infinite weary travelers , the night manager assigns every current guest to the first prime number , 2 , raised to the power of their current room number . so , the current occupant of room number 7 goes to room number 2^7 , which is room 128 . the night manager then takes the people on the first of the infinite buses and assigns them to the room number of the next prime , 3 , raised to the power of their seat number on the bus . so , the person in seat number 7 on the first bus goes to room number 3^7 or room number 2,187 . this continues for all of the first bus . the passengers on the second bus are assigned powers of the next prime , 5 . the following bus , powers of 7 . each bus follows : powers of 11 , powers of 13 , powers of 17 , etc . since each of these numbers only has 1 and the natural number powers of their prime number base as factors , there are no overlapping room numbers . all the buses ' passengers fan out into rooms using unique room-assignment schemes based on unique prime numbers . in this way , the night manager can accommodate every passenger on every bus . although , there will be many rooms that go unfilled , like room 6 , since 6 is not a power of any prime number . luckily , his bosses were n't very good in math , so his job is safe . the night manager 's strategies are only possible because while the infinite hotel is certainly a logistical nightmare , it only deals with the lowest level of infinity , mainly , the countable infinity of the natural numbers , 1 , 2 , 3 , 4 , and so on . georg cantor called this level of infinity aleph-zero . we use natural numbers for the room numbers as well as the seat numbers on the buses . if we were dealing with higher orders of infinity , such as that of the real numbers , these structured strategies would no longer be possible as we have no way to systematically include every number . the real number infinite hotel has negative number rooms in the basement , fractional rooms , so the guy in room 1/2 always suspects he has less room than the guy in room 1 . square root rooms , like room radical 2 , and room pi , where the guests expect free dessert . what self-respecting night manager would ever want to work there even for an infinite salary ? but over at hilbert 's infinite hotel , where there 's never any vacancy and always room for more , the scenarios faced by the ever-diligent and maybe too hospitable night manager serve to remind us of just how hard it is for our relatively finite minds to grasp a concept as large as infinity . maybe you can help tackle these problems after a good night 's sleep . but honestly , we might need you to change rooms at 2 a.m .
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each bus follows : powers of 11 , powers of 13 , powers of 17 , etc . since each of these numbers only has 1 and the natural number powers of their prime number base as factors , there are no overlapping room numbers . all the buses ' passengers fan out into rooms using unique room-assignment schemes based on unique prime numbers .
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why are there no overlapping room numbers when we use the natural number powers of the prime numbers to assign room numbers ?
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the city sky is , frankly , rather boring . if you look up at the patches of murk between buildings , you might be able to pick out the big dipper , or perhaps , orion 's belt . but hold on . look at that murky patch again and hold our your thumb . how many stars do you think are behind it ? ten , twenty ? guess again . if you looked at that thumbnail-sized patch of sky with the hubble space telescope , instead of points of light , you 'd see smudges . these are n't stars . they 're galaxies , just like our milky way . cities of billions of stars , and more than 1,000 of them are hidden behind your thumb . the universe is bigger than you can see from the city , and even bigger than the starry sky you can see from the countryside . this is the universe as astrophysicists see it , with more stars than all the grains of sand on earth . by staring up at the stars at night , you 've taken part in the oldest science in human history . the study of the heavens is older than navigation , agriculture , perhaps even language itself . yet unlike other sciences , astronomy is purely observational . we can not control the parameters of our experiments from lab benches . our best technology can send man to the moon , and probes to the edge of the solar system . but these distances are vanishingly small compared to the yawning gulfs between stars . so how can we know so much about other galaxies , what they 're made of , how many there are , or that they 're even there at all ? well , we can start with the first thing we see when we look up at night : the stars . what we are trying to learn is their properties . what are they made of ? how hot are they ? how massive ? how old ? how far are they from earth ? and believe it or not , we can learn all of these things simply from the light shining in the sky . we can decipher one kind of stellar message by turning starlight into rainbows . when you look at a rainbow on earth , you 're really looking at light from our sun being scattered through water droplets in the atmosphere into all the different wavelengths that make it up . and we study the light from other stars , we can create rainbows on demand using not water droplets , but other specific instruments that disperse light . when we look at the scattered light from our sun , we see something strange : dark lines in our rainbow . these lines are the characteristic fingerprints of atoms . each type of atom in the solar atmosphere soaks up light at specific wavelengths , and the amount of absorption depends on how many of these atoms there are . so by observing how much light is missing at these characteristic wavelengths , we can tell not only what elements are in the sun 's atmosphere , but even their concentrations . and the same idea can be applied to study other stars . make a spectral rainbow , see what 's missing , and figure out which elements are present . bingo . now you know what stars are made of . but we are n't restricted to just the wavelengths that our eyes perceive . consider radio waves . yes , they can bring the billboard top 100 to your car , but they can also travel almost unimpeded through space . because they 've come so far , radio waves can tell us the very early history of the universe , from just a few thousand years after the big bang . we can also study the infrared light , emitted by colder objects , like the gas and dust clouds in space , and the ultraviolet light from the hot stars recently born from those clouds . studying different wavelengths not only gives us a more complete picture of any single object but also different views of the universe . for this reason , astrophysicists use several different kinds of telescopes covering the spectrum from the infrared to the ultraviolet to the x-ray , from giant radio dishes to giant silver mirrors to space satellites , detecting light that would be otherwise blocked by the earth 's atmosphere . astrophysicists do n't just see the billions of stars among the billions of galaxies in the universe . they hear , feel and sense them through many channels , each revealing a different story . but it all begins with light , the kind we can see and the kind we ca n't . want to know the secrets of the universe ? just follow the light .
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we can decipher one kind of stellar message by turning starlight into rainbows . when you look at a rainbow on earth , you 're really looking at light from our sun being scattered through water droplets in the atmosphere into all the different wavelengths that make it up . and we study the light from other stars , we can create rainbows on demand using not water droplets , but other specific instruments that disperse light .
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why have humans evolved to be sensitive only to optical light ? why might this be an advantage ? why might it be a disadvantage ? [ hint : what wavelength does the sun preferentially emit its energy ? ] if there are organisms elsewhere in the universe sensitive to the other wavelengths , what would they look like ? sketch your idea .
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the idea of human rights is that each one of us , no matter who we are or where we are born , is entitled to the same basic rights and freedoms . human rights are not privileges , and they can not be granted or revoked . they are inalienable and universal . that may sound straighforward enough , but it gets incredibly complicated as soon as anyone tries to put the idea into practice . what exactly are the basic human rights ? who gets to pick them ? who enforces them , and how ? the history behind the concept of human rights is a long one . throughout the centuries and across societies , religions , and cultures we have struggled with defining notions of rightfulness , justice , and rights . but one of the most modern affirmations of universal human rights emerged from the ruins of world war ii with the creation of the united nations . the treaty that established the un gives as one of its purposes to reaffirm faith in fundamental human rights . and with the same spirit , in 1948 , the un general assembly adopted the universal declaration of human rights . this document , written by an international committee chaired by eleanor roosevelt , lays the basis for modern international human rights law . the declaration is based on the principle that all human beings are born free and equal in dignity and rights . it lists 30 articles recognizing , among other things , the principle of nondiscrimination and the right to life and liberty . it refers to negative freedoms , like the freedom from torture or slavery , as well as positive freedoms , such as the freedom of movement and residence . it encompasses basic civil and political rights , such as freedom of expression , religion , or peaceful assembly , as well as social , economic , and cultural rights , such as the right to education and the right to freely choose one 's occupation and be paid and treated fairly . the declaration takes no sides as to which rights are more important , insisting on their universality , indivisibility , and interdependence . and in the past decades , international human rights law has grown , deepening and expanding our understanding of what human rights are , and how to better protect them . so if these principles are so well-developed , then why are human rights abused and ignored time and time again all over the world ? the problem in general is that it is not at all easy to universally enforce these rights or to punish transgressors . the udhr itself , despite being highly authoritative and respected , is a declaration , not a hard law . so when individual countries violate it , the mechanisms to address those violations are weak . for example , the main bodies within the un in charge of protecting human rights mostly monitor and investigate violations , but they can not force states to , say , change a policy or compensate a victim . that 's why some critics say it 's naive to consider human rights a given in a world where state interests wield so much power . critics also question the universality of human rights and emphasize that their development has been heavily guided by a small number of mostly western nations to the detriment of inclusiveness . the result ? a general bias in favor of civil policital liberties over sociopolitical rights and of individual over collective or groups rights . others defend universal human rights laws and point at the positive role they have on setting international standards and helping activists in their campaigns . they also point out that not all international human rights instruments are powerless . for example , the european convention on human rights establishes a court where the 47 member countries and their citizens can bring cases . the court issues binding decisions that each member state must comply with . human rights law is constantly evolving as are our views and definitions of what the basic human rights should be . for example , how basic or important is the right to democracy or to development ? and as our lives are increasingly digital , should there be a right to access the internet ? a right to digital privacy ? what do you think ?
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the treaty that established the un gives as one of its purposes to reaffirm faith in fundamental human rights . and with the same spirit , in 1948 , the un general assembly adopted the universal declaration of human rights . this document , written by an international committee chaired by eleanor roosevelt , lays the basis for modern international human rights law .
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explain the role , content and impact of the un universal declaration of human rights .
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you 've probably seen an email or an internet post about how weird and random english spelling seems to be . but what if i told you that it actually makes perfect sense ? in fact , that 's spelling 's job : making sense . think of spelling a word as peeling back the layers of an onion . the first layer is a word 's sense and meaning . often there are multiple layers of meaning . another layer is the word 's structure . think of the center of the onion as a word 's base element , its essential kernel of meaning . a free-base element , like o-n-e , or t-w-o , can stand on its own as a word , like one , or two . a bound base , like the r-u-p-t of `` erupt '' or `` rupture '' needs another element in order to surface in a word . two or more bases give us compounds , like `` twofold '' or `` someone '' or `` bankrupt . '' once we figure out a word 's meaningful elements , we can peel back its history to shed a little more light on why it 's spelled as it is . the word `` two , '' for example , needs its `` w '' in order to mark its connection to words like `` twice , '' `` twelve , '' `` twenty , '' `` twin '' and `` between . '' a word 's history is another layer of the onion . with that understanding , let 's investigate the word `` one . '' first we need to check in with what it means . unique , single , solitary . `` one 's '' historical layers include its relatives `` only , '' `` once , '' `` eleven , '' and even `` a , '' `` an '' and `` any . '' but it 's the morphological relatives - the ones that share the base o-n-e - that are really astonishing . there are the familiar ones , like `` anyone , '' and `` one-track '' and `` oneself '' - those are obvious . but let 's take a look at some unexpected derivations of the word `` one . '' the word `` alone '' is built from the prefix a-l plus the base o-n-e . it 's the same a-l prefix that we see in `` always , '' `` already , '' `` almighty '' and `` almost . '' it means `` all . '' the word `` alone '' means `` all one . '' it was misanalysed in the middle ages as having the prefix `` a , '' like in `` asleep '' and `` awake '' and `` around , '' and a new base was born : l-o-n-e , which then developed into its own family . in the word `` atone , '' we find the familiar preposition `` at '' compounded with the base o-n-e. see , when we atone for something we 've done wrong , we attempt to make things whole again , to fix what 's broken , to be at one again with whomever we hurt . but here 's perhaps the best one of all : the word `` onion , '' which is also frequently derided as irregular or crazy , for its spelling of `` uh '' with an o . but again , if we look into the word 's structure , and its history , it 's a mystery no more . when we look at the roots of an onion , we learn that it is written as o-n-e plus i-o-n , the same suffix we find in `` tension , '' `` action , '' `` union '' and thousands of other words in english . unlike the many cloves in a head of garlic , an onion has a single bulb . it is marked by the state or condition of oneness . like an onion , english is one - one single writing system shared across time and space . its structure and its history have many layers , and peeling them apart can really add flavor to our language and spice up our understanding . see , spelling is never just about spelling , but about how written words make sense . it 's almost enough to make you want to cry .
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its structure and its history have many layers , and peeling them apart can really add flavor to our language and spice up our understanding . see , spelling is never just about spelling , but about how written words make sense . it 's almost enough to make you want to cry .
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many people misunderstand how spelling works and what its purpose is . what is the primary purpose -- the first consideration -- of the english spelling system ?
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translator : andrea mcdonough reviewer : bedirhan cinar you believe that the sun is much larger than the earth , that the earth is a roughly spherical planet that rotates on its axis every 24 hours and it revolves around the sun once every 365 days . you believe that you were born on a particular date , that you were born to two human parents and that each of your human parents was born on an earlier date . you believe that other human beings have thoughts and feelings like you do and that you are not surrounded by humanoid robots . you believe all of these things and many more , not on the basis of direct observation , which ca n't , by itself , tell you very much about the relative size and motion of the sun and the earth , or about your own family history , or about what goes on in the minds of other humans . instead , these beliefs are mostly based on what you 've been told . without spoken and written testimonies , human beings could not pass on knowledge from one person to another , let alone from one generation to another . we would know much , much less about the world around us . so learning about a topic by asking an expert on that topic , or appealing to authority , helps us gain knowledge , but , it does n't always . even the most highly respected authorities can turn out to be wrong . occasionally this happens because a highly respected authority is dishonest and claims to know something that she or he really does n't know . sometimes it happens just because they make a mistake . they think they know when they do n't know . for example , a number of respected economists did not expect the financial collapse of 2008 . they turned out to be wrong . maybe they were wrong because they were overlooking some important evidence . maybe they were wrong because they were misinterpreting some of the evidence they had noticed . or maybe they were wrong simply because they were reasoning carelessly from the total body of their evidence . but whatever the reason , they turned out to be wrong and many people who trusted their authority ended up losing lots of money , losing lots of other people 's money , on account of that misplaced trust . so while appealing to authority can sometimes provide us with valuable knowledge , it also can sometimes be the cause of monumental errors . it 's important to all of us to be able to distinguish those occasions on which we can safely and reasonably trust authority from those occasions on which we ca n't . but how do we do that ? in order to do that , nothing is more useful than an authority 's track record on a particular topic . if someone turns out to perform well in a given situation much of the time , then it 's likely that he or she will continue to perform well in that same situation , at least in the near term . and this generalization holds true of the testimony of authorities as much as of anything else . if someone can consistently pick winners in both politics and baseball , then we should probably trust him or her to keep on picking winners in both politics or baseball , though maybe not in other things where his or her track record may be less stellar . if other forecasters have a poorer track record on those same two topics , then we should n't trust them as much . so whenever you 're considering whether to trust the testimony of some authority , the first question to ask yourself is , `` what 's their track record on this topic ? '' and notice that you can apply the very same lesson to yourself . your instincts tell you that you 've just met mr . right , but what sort of track record do your instincts have on topics like this one ? have your instincts proven themselves to be worthy of your trust ? just as we judge other people 's testimony by their track record , so , too , we can judge our own instincts by their track record . and this brings us one step closer to an objective view of ourselves and our relation to the world around us .
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your instincts tell you that you 've just met mr . right , but what sort of track record do your instincts have on topics like this one ? have your instincts proven themselves to be worthy of your trust ?
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nate has been forecasting the results of horse races , and makes a correct prediction 85 % of the time . today , nate predicts that silverado will win the horse race . today ’ s horse race ( like most of the others that nate has considered ) is a race among 10 horses . there is nothing that specially distinguishes today ’ s horse race from others or that distinguishes silverado from other horses that nate has predicted to win . how confident should you be that silverado will win ?
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how many times does the chorus repeat in your favorite song ? and , take a moment to think , how many times have you listened to it ? chances are you 've heard that chorus repeated dozens , if not hundreds , of times , and it 's not just popular songs in the west that repeat a lot . repetition is a feature that music from cultures around the world tends to share . so , why does music rely so heavily on repetition ? one part of the answer come from what psychologists call the mere-exposure effect . in short , people tend to prefer things they 've been exposed to before . for example , a song comes on the radio that we do n't particularly like , but then we hear the song at the grocery store , at the movie theater and again on the street corner . soon , we are tapping to the beat , singing the words , even downloading the track . this mere-exposure effect does n't just work for songs . it also works for everything from shapes to super bowl ads . so , what makes repetition so uniquely prevalent in music ? to investigate , psychologists asked people to listen to musical compositions that avoided exact repetition . they heard excerpts from these pieces in either their original form , or in a version that had been digitally altered to include repetition . although the original versions had been composed by some of the most respected 20th century composers , and the repetitive versions had been assembled by brute force audio editing , people rated the repetitive versions as more enjoyable , more interesting and more likely to have been composed by a human artist . musical repetition is deeply compelling . think about the muppets classic , `` mahna mahna . '' if you 've heard it before , it 's almost impossible after i sing , `` mahna mahna , '' not to respond , `` do doo do do do . '' repetition connects each bit of music irresistibly to the next bit of music that follows it . so when you hear a few notes , you 're already imagining what 's coming next . your mind is unconsciously singing along , and without noticing , you might start humming out loud . recent studies have shown that when people hear a segment of music repeated , they are more likely to move or tap along to it . repetition invites us into music as imagined participants , rather than as passive listeners . research has also shown that listeners shift their attention across musical repetitions , focusing on different aspects of the sound on each new listen . you might notice the melody of a phrase the first time , but when it 's repeated , your attention shifts to how the guitarist bends a pitch . this also occurs in language , with something called semantic satiation . repeating a word like atlas ad nauseam can make you stop thinking about what the word means , and instead focus on the sounds : the odd way the `` l '' follows the `` t. '' in this way , repetition can open up new worlds of sound not accessible on first hearing . the `` l '' following the `` t '' might not be aesthetically relevant to `` atlas , '' but the guitarist pitch bending might be of critical expressive importance . the speech to song illusion captures how simply repeating a sentence a number of times shifts listeners attention to the pitch and temporal aspects of the sound , so that the repeated spoken language actually begins to sound like it is being sung . a similar effect happens with random sequences of sound . people will rate random sequences they 've heard on repeated loop as more musical than a random sequence they 've only heard once . repetition gives rise to a kind of orientation to sound that we think of as distinctively musical , where we 're listening along with the sound , engaging imaginatively with the note about to happen . this mode of listening ties in with our susceptibility to musical ear worms , where segments of music burrow into our head , and play again and again , as if stuck on repeat . critics are often embarrassed by music 's repetitiveness , finding it childish or regressive , but repetition , far from an embarrassment , is actually a key feature that gives rise to the kind of experience we think about as musical .
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you might notice the melody of a phrase the first time , but when it 's repeated , your attention shifts to how the guitarist bends a pitch . this also occurs in language , with something called semantic satiation . repeating a word like atlas ad nauseam can make you stop thinking about what the word means , and instead focus on the sounds : the odd way the `` l '' follows the `` t. '' in this way , repetition can open up new worlds of sound not accessible on first hearing .
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the semantic satiation effect refers to :
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far beneath the palace of the treacherous king minos , in the damp darkness of an inescapable labryinth , a horrific beast stalks the endless corridors of its prison , enraged with a bloodlust so intense that its deafening roar shakes the earth . it is easy to see why the minotaur myth has a long history of being disregarded as pure fiction . however , there 's a good chance that the minotaur and other monsters and gods were created by our early ancestors to rationalize the terrifying things that they saw in the natural world but did not understand . and while we ca n't explain every aspect of their stories , there may be some actual science that reveals itself when we dissect them for clues . so , as far as we know , there have never been human-bull hybrids . but the earliest material written about the minotaur does n't even mention its physical form . so that 's probably not the key part of the story . what the different tellings do agree upon , however , is that the beast lives underground , and when it bellows , it causes tremendous problems . the various myths are also specific in stating that genius inventor daedalus , carved out the labyrinth beneath the island of crete . archeological attempts to find the fabled maze have come up empty handed . but crete itself has yielded the most valuable clue of all in the form of seismic activity . crete sits on a piece of continental crust called the aegean block , and has a bit of oceanic crust known as the nubian block sliding right beneath it . this sort of geologic feature , called a subduction zone , is common all over the world and results in lots of earthquakes . however , in crete the situation is particularly volatile as the nubian block is attached to the massive buoyant continental crust that is africa . when the nubian block moves , it does not go down nearly as easily or as steeply as oceanic crust does in most other subduction zones . instead , it violently and abruptly forces sections of the mediterranean upwards in an event called uplift , and crete is in uplift central . in the year 2014 , crete had more than 1300 earthquakes of magnitude 2.0 or higher . by comparison , in the same period of time , southern california , a much larger area , experienced a mere 255 earthquakes . of course , we do n't have detailed seismic records from the days of king minos , but we do know from fossil records and geologic evidence that crete has experienced serious uplift events that sometimes exceeded 30 feet in a single moment . contrast this for a moment with the island of hawaii , where earthquakes and volcanic activity were tightly woven to legends surrounding pele , a goddess both fiery and fair . like the minotaur , her myths included tales of destruction , but they also contained elements of dance and creation . so why did hawaii end up with pele and crete end up with the minotaur ? the difference likely comes down to the lava that followed many of hawaii 's worst earthquakes . the lava on hawaii is made of basalt , which once cooled , is highly fertile . within a couple of decades of terrible eruptions , islanders would have seen vibrant green life thriving on new peninsulas made of lava . so it makes sense that the mythology captured this by portraying pele as creator as well as a destroyer . as for the people of crete , their earthquakes brought only destruction and barren lands , so perhaps for them the unnatural and deadly minotaur was born . the connections between mythical stories and the geology of the regions where they originated teach us that mythology and science are actually two sides of the same coin . both are rooted in explaining and understanding the world . the key difference is that where mythology uses gods , monsters and magic , science uses measurements , records and experiments .
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so why did hawaii end up with pele and crete end up with the minotaur ? the difference likely comes down to the lava that followed many of hawaii 's worst earthquakes . the lava on hawaii is made of basalt , which once cooled , is highly fertile . within a couple of decades of terrible eruptions , islanders would have seen vibrant green life thriving on new peninsulas made of lava .
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why is basalt lava likely important to pele 's status as a creator goddess ?
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without a doubt , the most exciting scientific observation of 2012 was the discovery of a new particle at the cern laboratory that could be the higgs boson , a particle named after physicist peter higgs . the higgs field is thought to give mass to fundamental , subatomic particles like the quarks and leptons that make up ordinary matter . the higgs bosons are wiggles in the field , like the bump you see when you twitch a rope . but how does this field give mass to particles ? if this sounds confusing to you , you 're not alone . in 1993 , the british science minister challenged physicists to invent a simple way to understand all this higgs stuff . the prize was a bottle of quality champagne . the winning explanation went something like this : suppose there 's a large cocktail party at the cern laboratory filled with particle physics researchers . this crowd of physicists represents the higgs field . if a tax collector entered the party , nobody would want to talk to them , and they could very easily cross the room to get to the bar . the tax collector would n't interact with the crowd in much the same way that some particles do n't interact with the higgs field . the particles that do n't interact , like photons for example , are called massless . now , suppose that peter higgs entered the same room , perhaps in search of a pint . in this case , the physicists will immediately crowd around higgs to discuss with him their efforts to measure the properties of his namesake boson . because he interacts strongly with the crowd , higgs will move slowly across the room . continuing our analogy , higgs has become a massive particle through his interactions with the field . so , if that 's the higgs field , how does the higgs boson fit into all of this ? let 's pretend our crowd of party goers is uniformly spread across the room . now suppose someone pops their head in the door to report a rumor of a discovery at some distant , rival laboratory . people near the door will hear the rumor , but people far away wo n't , so they 'll move closer to the door to ask . this will create a clump in the crowd . as people have heard the rumor , they will return to their original positions to discuss its implications , but people further away will then ask what 's going on . the result will be a clump in the crowd that moves across the room . this clump is analogous to the higgs boson . it is important to remember that it is not that massive particles interact more with the higgs field . in our analogy of the party , all particles are equal until they enter the room . both peter higgs and the tax collector have zero mass . it is the interaction with the crowd that causes them to gain mass . i 'll say that again . mass comes from interactions with a field . so , let 's recap . a particle gets more or less mass depending on how it interacts with a field , just like different people will move through the crowd at different speeds depending on their popularity . and the higgs boson is just a clump in the field , like a rumor crossing the room . of course , this analogy is just that -- an analogy , but it 's the best analogy anyone has come up with so far . so , that 's it . that 's what the higgs field and the higgs boson is all about . continuing research will tell us if we found it , and the reward will probably be more than just a bottle of champagne .
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because he interacts strongly with the crowd , higgs will move slowly across the room . continuing our analogy , higgs has become a massive particle through his interactions with the field . so , if that 's the higgs field , how does the higgs boson fit into all of this ?
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the analogy likens a tax collector to a massless particle , as she doesn ’ t interact much with the field and peter higgs as a massive particle , as higgs interacts a great deal with the field . in reality , there are a variety of subatomic particles , with a varying range of masses . how can the analogy be extended to accommodate these particles with different masses ?
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that 's what we like to see ... haha have this one handy as well ... . so zinc again is an abundant metal but it 's a metal that we all need for life , it 's part of enzymes and it 's part of of many many biologically mediated processes . i do n't know what else to say about zinc it 's a pretty boring metal . it really is a boring metal . - now i understand what my collegue said thinks bit boring . this is n't always the case and when you combine it with some other elements , it can get quite frisky , as you 'll see in a bit . - zinc is a really soft metal , it 's sort of greyish in colour , it reacts very easily with acids to produce hydrogen . in fact it 's the way that people make hydrogen in the lab , or used to . now they usually buy it in cylinders . - zinc is often found on things like roofs as well , very very high quality roofing material , very slow to oxidise . - zinc is used very widely as a coating on iron . so called galvanizing . you put a thin layer of zinc and the zinc then corrodes instead of the iron , so that it stops the iron rusting , at least for quite a long time . you can see it on corrugated iron roofs , metal gates in the countryside and so on . so this is diethylzinc , so it 's c4h10zn . - zinc is quite important biologically , and there are all sorts of enzymes in our bodies that use zinc . and particularly one called carbonic anhydrase that catalyse at the reaction of co2 and water and so without zinc , none of us could survive . the delivery of the statement that zinc is boring were greatly under anticipating the result of this experiment . really , you 've built it up now . that 's what we like to see . have this one handy as well . let 's give this a go . - i told you to fix the stuff . so who says zinc 's boring ? shall we do it again ? wow ... no i do n't think zinc is in the least bit boring . i do n't think that most elements are interesting , but zinc is interesting because it 's in the same group as cadmium and mercury and cadmium and mercury are both pretty poisonous . but zinc is essential to life . if you do n't have enough zinc you ca n't smell things . there are all sorts of enzymes in your body and those of other creatures , that wo n't work without zinc . so it 's really good . you may be bored about it , but if you did n't have zinc , you would n't even be able to be bored . www.periodicvideos.com . . . . . . . . . . . . captions by www.subply.com
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wow ... no i do n't think zinc is in the least bit boring . i do n't think that most elements are interesting , but zinc is interesting because it 's in the same group as cadmium and mercury and cadmium and mercury are both pretty poisonous . but zinc is essential to life .
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the professor noted a big difference between zinc and the other two metals of this group , cadmium and mercury ... what is it ?
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these are the first five elements of a number sequence . can you figure out what comes next ? pause here if you want to figure it out for yourself . answer in : 3 answer in : 2 answer in : 1 there is a pattern here , but it may not be the kind of pattern you think it is . look at the sequence again and try reading it aloud . now , look at the next number in the sequence . 3 , 1 , 2 , 2 , 1 , 1 . pause again if you 'd like to think about it some more . answer in : 3 answer in : 2 answer in : 1 this is what 's known as a look and say sequence . unlike many number sequences , this relies not on some mathematical property of the numbers themselves , but on their notation . start with the left-most digit of the initial number . now , read out how many times it repeats in succession followed by the name of the digit itself . then move on to the next distinct digit and repeat until you reach the end . so the number 1 is read as `` one one '' written down the same way we write eleven . of course , as part of this sequence , it 's not actually the number eleven , but 2 ones , which we then write as 2 1 . that number is then read out as 1 2 1 1 , which written out we 'd read as one one , one two , two ones , and so on . these kinds of sequences were first analyzed by mathematician john conway , who noted they have some interesting properties . for instance , starting with the number 22 , yields an infinite loop of two twos . but when seeded with any other number , the sequence grows in some very specific ways . notice that although the number of digits keeps increasing , the increase does n't seem to be either linear or random . in fact , if you extend the sequence infinitely , a pattern emerges . the ratio between the amount of digits in two consecutive terms gradually converges to a single number known as conway 's constant . this is equal to a little over 1.3 , meaning that the amount of digits increases by about 30 % with every step in the sequence . what about the numbers themselves ? that gets even more interesting . except for the repeating sequence of 22 , every possible sequence eventually breaks down into distinct strings of digits . no matter what order these strings show up in , each appears unbroken in its entirety every time it occurs . conway identified 92 of these elements , all composed only of digits 1 , 2 , and 3 , as well as two additional elements whose variations can end with any digit of 4 or greater . no matter what number the sequence is seeded with , eventually , it 'll just consist of these combinations , with digits 4 or higher only appearing at the end of the two extra elements , if at all . beyond being a neat puzzle , the look and say sequence has some practical applications . for example , run-length encoding , a data compression that was once used for television signals and digital graphics , is based on a similar concept . the amount of times a data value repeats within the code is recorded as a data value itself . sequences like this are a good example of how numbers and other symbols can convey meaning on multiple levels .
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that gets even more interesting . except for the repeating sequence of 22 , every possible sequence eventually breaks down into distinct strings of digits . no matter what order these strings show up in , each appears unbroken in its entirety every time it occurs .
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which mathematician invented the sequence ?
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a 13,000 mile dragon of earth and stone winds its way through the countryside of china with a history almost as long and serpentine as the structure . the great wall began as multiple walls of rammed earth built by individual feudal states during the chunqiu period to protect against nomadic raiders north of china and each other . when emperor qin shi huang unified the states in 221 bce , the tibetan plateau and pacific ocean became natural barriers , but the mountains in the north remained vulnerable to mongol , turkish , and xiongnu invasions . to defend against them , the emperor expanded the small walls built by his predecessors , connecting some and fortifying others . as the structures grew from lintao in the west to liaodong in the east , they collectively became known as the long wall . to accomplish this task , the emperor enlisted soldiers and commoners , not always voluntarily . of the hundreds of thousands of builders recorded during the qin dynasty , many were forcibly conscripted peasants and others were criminals serving out sentences . under the han dynasty , the wall grew longer still , reaching 3700 miles , and spanning from dunhuang to the bohai sea . forced labor continued under the han emperor han-wudi , and the walls reputation grew into a notorious place of suffering . poems and legends of the time told of laborers buried in nearby mass graves , or even within the wall itself . and while no human remains have been found inside , grave pits do indicate that many workers died from accidents , hunger and exhaustion . the wall was formidable but not invincible . both genghis and his son khublai khan managed to surmount the wall during the mongol invasion of the 13th century . after the ming dynasty gained control in 1368 , they began to refortify and further consolidate the wall using bricks and stones from local kilns . averaging 23 feet high and 21 feet wide , the walls 5500 miles were punctuated by watchtowers . when raiders were sighted , fire and smoke signals traveled between towers until reinforcements arrived . small openings along the wall let archers fire on invaders , while larger ones were used to drop stones and more . but even this new and improved wall was not enough . in 1644 , northern manchu clans overthrew the ming to establish the qing dynasty , incorporating mongolia as well , thus , for the second time , china was ruled by the very people the wall had tried to keep out . with the empire 's borders now extending beyond the great wall , the fortifications lost their purpose . and without regular reinforcement , the wall fell into disrepair , rammed earth eroded , while brick and stone were plundered for building materials . but its job was n't finished . during world war ii , china used sections for defense against japanese invasion , and some parts are still rumored to be used for military training . but the wall 's main purpose today is cultural . as one of the largest man-made structures on earth , it was granted unesco world heritage status in 1987 . originally built to keep people out of china , the great wall now welcomes millions of visitors each year . in fact , the influx of tourists has caused the wall to deteriorate , leading the chinese government to launch preservation initiatives . it 's also often acclaimed as the only man-made structure visible from space . unfortunately , that 's not at all true . in low earth orbit , all sorts of structures , like bridges , highways and airports are visible , and the great wall is only barely discernible . from the moon , it does n't stand a chance . but regardless , it 's the earth we should be studying it from because new sections are still discovered every few years , branching off from the main body and expanding this remarkable monument to human achievement .
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in fact , the influx of tourists has caused the wall to deteriorate , leading the chinese government to launch preservation initiatives . it 's also often acclaimed as the only man-made structure visible from space . unfortunately , that 's not at all true .
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true or false : the great wall is the only visible man-made structure in space .
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( music ) i want everyone to put their hands on top of their head . yeah , yeah , yeah . put your hands on top of your head . just relax . just stay calm . everything will be nice and smooth if you just participate and just relax , okay ? yeah . all right , now put your hands down . do n't be no hero . put your hands down . okay ? all right . now . cool . good . i want you to run all that financial aid . yeah , sucka , put the scholarships in the bag , yeah , yeah . put the scholarships in the bag . yeah , you too , yeah , yeah , yeah . yeah , you . yeah , yeah . you over there , go put the pell grants in the bag . put the pell grants in there too . yeah , you . go . yeah , yeah , yeah . you , go over to that booth and get me some of them subsidized , some of them subsidized loans . it ai n't a game no more . i know you 're hiding the money somewhere here . with all this tuition you got me and my homies payin ' -- woo ! -- i 'm about to get gangster-scholar up in here . up in here . i 'm about to go n.w.a . meets beastie boys if i do n't see the cash , man . cause we 're not gon na take it . ♪ oh ... oh , you thought i was playing . oh , you thought this was a game . back up , back up . mind your business , that 's all . what do you , think this is a game ? what ? huh ? you do n't even know me . i 'll say something else . do n't call me crazy . do not call me -- rives , tell 'em do n't call me crazy before i go crazy . i 'm telling you , now i 'm about to go crazy . i 'm about to go tupac thug life in here . like , `` i ai n't a killer but do n't push me . revenge is like the sweetest joy -- '' woo ! i 'm about to go biggie smalls brooklyn type , like , `` super nintendo , sega genesis . when i was dead broke -- '' woo ! i 'm about to go krs-one cuckoo for cocoa puffs-type wild . like , `` wa da da dang , wa da da da dang , listen to my nine millimeter go bang . '' you know what ? you are dumb . you are really dumb . hide your kids , hide your wife , 'cause we gettin ' financial aid all up and in and around here . you think this is a game ? you think i want to be out here doing this ? do you know how hard it was to find these guns ? all right , i 'm sorry . you understand ? i 'm just trying to get my education . you know what i mean ? i 'm just trying to fight for the opportunity that my great-great-great-grandfather died for , you know what i 'm saying ? you know how my ancestors did sit-ins , just so i can sit in a classroom . and all these years , all y'all been doing is strangling the life out of my bank statement , leaving my pockets as vacant as parking lots . professor willie lynch taught you well , huh ? keep the body , take the money . force feed my people deception and failure . condition our brains to malfunction at the sight of success . just keep the cycle going . make us pay for an education that will end up failing us . put us in debt so we 're giving back the money we earned from our back-breaking work . this seems all too familiar . sounds like the rust of shackles locking their way onto my degree . sounds like the thirteenth amendment in reverse . lecture halls should n't feel like cotton fields , should n't sound like muffled freedom songs trapped in the jaws of a generation 's dreams . oho ! oh , it all makes sense . give us enough to get by but not enough to provide for ourselves . keep us psychologically feeble so we lose our purpose in the process . stop thieving our aspirations out of our sleep . do n't call it financial aid if you 're not helping anyone with it . we have fought . we have fought way too hard to let green paper build a barricade in front of our futures . i will not let you potentially rob food out of my children 's stomach . best believe i 'm going out blasting . i ai n't no killer , but do n't push me . i wish it did n't come to this , but i have to for my cousins in haiti who do n't even know what a college looks like , for my best friend raymond sitting in cell block nine instead of a university , for the nooses hanging my gpa by its neck . there is no other option . there is no other way . just , please , put the money in the bag . put the money in the bag . i just want to go to school , man . i just want to get my education . i just want to learn . i just want to grow . put the money in the bag , please . just put the money in the bag .
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( music ) i want everyone to put their hands on top of their head . yeah , yeah , yeah .
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in doing so , lissaint is careful to appropriate the language of an actual robbery , as in
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cadmium ? yes ok oh yeah , that ’ s some ! that is cool man ! so cadmium is an element which is really quite similar to mercury and the way that most people have seen cadmium is that cadmium sulphide has a very strong orange colour and it is therefore used for dying things yellow or orange . if you look round your house or your parents ’ house , you may easily find a cast iron pot which has , a cooking pot , which has nice orange sides and orange lid and this is using cadmium sulphide as a glaze . so this is a sample which was generated or which was used by some of our researchers in the school of chemistry many years ago and this is a sample of cadmium metal . now it ’ s very interesting because it is stored in this really quite nice box which was perhaps a medication that somebody had bought , but if we open it… it 's also i believe , to colour the plastic pipe that you see in the street for gas pipes and so on . i think it is coloured with a cadmium compound . now in both these applications , even though that cadmium is quite poisonous , that they are so strongly fixed into the materials that it isn ’ t a threat to people . and we can see the lumps of the metallic cadmium . now i am not going to touch the cadmium because we know of some of the issues with toxicity . but it is used very often in batteries , or it was traditionally used in batteries . it is really important that we dispose of our batteries in a correct way .
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cadmium ? yes ok oh yeah , that ’ s some !
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as the professor explained , cadmium compounds can be used as pigments . what color is cadmium sulfide ( cds ) , the most used pigment of this element ?
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while touring the remains of ancient alexandria , egypt , there are a few things that present-day explorers should look for . first , as you travel along the great harbor , keep your eyes open for large columns and statues . across the bay to your left is the island where the great lighthouse once stood . and as you make your way through the palaces of the royal quarter and reach the area where the library of alexandria once stood , keep your eyes open for sharks . because if you visit this section of alexandria , you 'll be fifteen feet deep in the mediterranean sea . though people are most familiar with plato 's fictional atlantis , many real underwater cities actually exist . places like alexandria , port royal , jamaica , and pavlopetri , greece . sunken cities are studied by scientists to help us understand the lives of our ancestors , the dynamic nature of our planet , and the impact of each on the other . water is essential for life , food sources , and transport , so many cities have been built along coast lines and river banks . however , these benefits also come with risks because natural forces that can sink a city are at their doorstep . take , for instance , an earthquake . june 7 , 1692 seemed like a normal morning in port royal , jamaica , then one of the richest ports in the world , but when a massive earthquake struck , two-thirds of port royal immediately sank to its rooftops . today , many buildings and elements of everyday life remain surprisingly intact on the sea floor , frozen in time . that includes a 300-year-old pocket watch that stopped at 11:43 , the moment port royal slipped beneath the carribean . and during the winter of 373 bce , the greek city of helike was struck by an earthquake so strong that it liquefied the sandy ground upon which the city was built . minutes later , a tsunami struck the city , and helike and its inhabitants sunk downwards into the mediterranean sea . centuries later , roman tourists would sail on the lagoon that formed and peer down at the city 's remains . earthquakes are sudden , unpredictable disasters that have drowned cities in an instant . luckily , however , throughout history , the majority of sunken cities were not submerged by a single cataclysmic event , but by a combination of more gradual processes . for instance , pavlopetri , the oldest known sunken city , was built on the southern coastline of greece 5,000 years ago . it 's an example of a city that was submerged due to what is called isostatic sea level change . 18,000 years ago when the ice age ended , glaciers began melting and the sea level rose globally until about 5,000 years ago . isostatic sea level change is n't caused by that melt water , but rather the earth 's crust slowly springing back from the released weight of the glaciers , making some places rise , and others sink . the ground around pavlopetri is still sinking at an average rate of a millimeter per year . but the ancient inhabitants were able to move gradually inland over several generations before they finally abandoned the city about 3,000 years ago . today , divers swim over the streets of pavlopetri and peer through ancient door jams into the foundations of houses and community buildings . they learn about the people who lived there by observing what they left behind . natural geological events , such as earthquakes and tsunamis , will continue to shape our continents , just as they have for millions of years . as increased global warming melts our polar ice caps at accelerated rates and sea levels rise , we will be forced to adapt , like pavlopetri 's inhabitants . undoubtedly , over the coming centuries , some of the coastal areas that we live in today will eventually be claimed by the water , too - cities like venice , new orleans , amsterdam , miami , and tokyo . imagine what future civilizations will learn about us as they swim around the ancient ruins of the cities that we live in today .
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undoubtedly , over the coming centuries , some of the coastal areas that we live in today will eventually be claimed by the water , too - cities like venice , new orleans , amsterdam , miami , and tokyo . imagine what future civilizations will learn about us as they swim around the ancient ruins of the cities that we live in today .
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what can sunken cities teach us about our cities today ?
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it 's a hot day , and you 've just downed several glasses of water , one after the other . behind the sudden urge that follows are two bean-shaped organs that work as fine-tuned internal sensors . they balance the amount of fluid in your body , detect waste in your blood , and know when to release the vitamins , minerals , and hormones you need to stay alive . say hello to your kidneys . the main role of these organs is to dispose of waste products and to turn them into urine . the body 's eight liters of blood pass through the kidneys between 20 and 25 times each day , meaning that , together , these organs filter about 180 liters every 24 hours . the ingredients in your blood are constantly changing as you ingest food and drink , which explains why the kidneys need to be on permanent duty . blood enters each kidney through arteries that branch and branch , until they form tiny vessels that entwine with special internal modules , called nephrons . in each kidney , 1 million of these nephrons form a powerful array of filters and sensors that carefully sift through the blood . this is where we see just how refined and accurate this internal sensing system is . to filter the blood , each nephron uses two powerful pieces of equipment : a blob-like structure called a glomerulus , and a long , stringy , straw-like tubule . the glomerulus works like a sieve , allowing only certain ingredients , such as vitamins and minerals , to pass into the tubule . then , this vessel 's job is to detect whether any of those ingredients are needed in the body . if so , they 're reabsorbed in amounts that the body needs , so they can circulate in the blood again . but the blood does n't only carry useful ingredients . it contains waste products , too . and the nephrons have to figure out what to do with them . the tubules sense compounds the body does n't need , like urea , left over from the breakdown of proteins , and redirects them as urine out of the kidneys and through two long sewers called ureters . the tubes empty their contents into the bladder to be discharged , ridding your body of that waste once and for all . there 's water in that urine , too . if the kidney detects too much of it in your blood , for instance , when you 've chugged several glasses at once , it sends the extra liquid to the bladder to be removed . on the other hand , low water levels in the blood prompt the kidney to release some back into the blood stream , meaning that less water makes it into the urine . this is why urine appears yellower when you 're less hydrated . by controlling water , your kidneys stabilize the body 's fluid levels . but this fine balancing act is n't the kidney 's only skill . these organs have the power to activate vitamin d to secrete a hormone called renin that raises blood pressure , and another hormone called erythropoietin , which increases red blood cell production . without the kidneys , our bodily fluids would spiral out of control . every time we ate , our blood would receive another load of unsifted ingredients . soon , the buildup of waste would overload our systems and we 'd expire . so each kidney not only keeps things running smoothly . it also keeps us alive . lucky then that we have two of these magical beans .
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they balance the amount of fluid in your body , detect waste in your blood , and know when to release the vitamins , minerals , and hormones you need to stay alive . say hello to your kidneys . the main role of these organs is to dispose of waste products and to turn them into urine .
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what do your kidneys do for you ?
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how old is the earth ? well , by counting the number of isotopes in a sample of rock that 's undergone radioactive decay , geologists have estimated the earth 's birthday , when it first formed from a solar nebula , to be 4.6 billion years ago . but just how long is that really ? here 's some analogies that might help you understand . for example , let 's imagine the entire history of earth until the present day as a single calendar year . on january 1st , the earth begins to form . by march 3rd , there 's the first evidence of single-celled bacteria . life remains amazingly unicellular until november 11th when the first multicellular organisms , known as the ediacaran fauna , come along . shortly thereafter , on november 16th at 6:08 p.m. is the cambrian explosion of life , a major milestone , when all of the modern phyla started to appear . on december 10th at 1:26 p.m. , the dinosaurs first evolve but are wiped out by an asteroid just two weeks later . on december 31st , the mighty roman empire rises and falls in just under four seconds . and columbus sets sail for what he thinks is india at three seconds to midnight . if you try to write the history of the earth using just one page per year , your book would be 145 miles thick , more than half the distance to the international space station . the story of the 3.2 million year-old australopithecine fossil known as lucy would be found on the 144th mile , just over 500 feet from the end of the book . the united states of america 's declaration of independence would be signed in the last half-inch . or if we compared geologic time to a woman stretching her arms to a span of six feet , the simple act of filing her nails would wipe away all of recorded human history . finally , let 's imagine the history of the earth as your life : from the moment you 're born to your first day of high school . your first word , first time sitting up , and first time walking would all take place while life on earth was comprised of single-celled organisms . in fact , the first multicellular organism would n't evolve until you were 12 years old and starting 7th grade , right around the time your science teacher is telling the class how fossils are formed . the dinosaurs do n't appear until three months into 8th grade and are soon wiped out right around spring break . three days before 9th grade begins , when you realize summer is over and you need new school supplies , lucy , the australopithecine , is walking around africa . as you finish breakfast and head outside to catch your bus 44 minutes before school , the neanderthals are going extinct throughout europe . the most recent glacial period ends as your bus drops you off 16 minutes before class . columbus sets sail 50 seconds before class as you 're still trying to find the right classroom . the declaration of independence is signed 28 seconds later as you look for an empty seat . and you were born 1.3 seconds before the bell rings . so , you see , the earth is extremely , unbelievably old compared to us humans with a fossil record hiding incredible stories to tell us about the past and possibly the future as well . but in the short time we 've been here , we 've learned so much and will surely learn more over the next decades and centuries , near moments in geological time .
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how old is the earth ? well , by counting the number of isotopes in a sample of rock that 's undergone radioactive decay , geologists have estimated the earth 's birthday , when it first formed from a solar nebula , to be 4.6 billion years ago .
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the earth has an incredibly long history . how does understanding geologic time and the significant geologic events of the past impact your understanding of humans ’ unique responsibility and place on earth ?
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i want to tell you all about a piece of american history that is so secret , that nobody has done anything about it for 167 years , until right now . and the way that we 're going to uncover this vestigial organ of america past is by asking this question : why ? as we all know -- ( laughter ) we are in the middle of another presidential election , hotly contested , as you can see . ( laughter ) but what you may not know is that american voter turnout ranks near the bottom of all countries in the entire world , 138th of 172 nations . this is the world 's most famous democracy . so ... why do we vote on tuesday ? does anybody know ? and as a matter of fact , michigan and arizona are voting today . here 's the answer : absolutely no good reason whatsoever . ( laughter ) i 'm not joking . you will not find the answer in the declaration of independence , nor will you find it in the constitution . it is just a stupid law from 1845 . ( laughter ) in 1845 , americans traveled by horse and buggy . as did i , evidently . it took a day to get to the county seat to vote , a day to get back , and you could n't travel on the sabbath , so , tuesday it was . i do n't often travel by horse and buggy , i would imagine most of you do n't , so when i found out about this , i was fascinated . i linked up with a group called , what else -- `` why tuesday ? '' to go and ask our nation 's most prominent elected leaders if they knew the answer to the question , `` why do we vote on tuesday ? '' ( video ) rick santorum : anybody knows ? ok , i 'm going to be stumped on this . anybody knows why we vote on tuesdays ? jacob soboroff : do you happen to know ? ron paul : on tuesdays ? js : the day after the first monday in november . rp : i do n't know how that originated . js : do you know why we do vote on tuesday ? newt gingrich : no . dick lugar : no , i do n't . ( laughter ) dianne feinstein : i do n't . darrell issa : no . john kerry : in truth , really , i 'm not sure why . js : ok , thanks very much . ( laughter ) js : these are people that live for election day , yet they do n't know why we vote on that very day . ( laughter ) chris rock said , `` they do n't want you to vote . if they did , we would n't vote on a tuesday in november . have you ever thrown a party on a tuesday ? ( laughter ) no , of course not . nobody would show up . '' ( laughter ) here 's the cool part . because we asked this question , `` why tuesday ? '' there is now this bill , the weekend voting act in the congress of the united states of america . it would move election day from tuesday to the weekend , so that -- duh -- more people can vote . ( applause ) it has only taken 167 years , but finally , we are on the verge of changing american history . thank you very much . ( applause ) thanks a lot . ( applause )
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because we asked this question , `` why tuesday ? '' there is now this bill , the weekend voting act in the congress of the united states of america . it would move election day from tuesday to the weekend , so that -- duh -- more people can vote . ( applause ) it has only taken 167 years , but finally , we are on the verge of changing american history .
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read more about other electoral systems . how does america ’ s election system compare and contrast to other systems ?
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many modern musical instruments are cumbersome or have a lot of parts . some need a stand or a stool . but the cajon is a drum , a stand and a seat all in one convenient box . and this simplicity may be key to its journey across continents and cultures to become one of the most popular percussion instruments in the world today . the cajon 's story begins in west africa , whose indigenousness people had rich musical traditions centered on drumming and dancing . when many of them were captured and brought to the americas as slaves , they brought this culture with them , but without their native instruments , they had to improvise . african slaves in coastal peru did n't have the materials or the opportunity to craft one of their traditional drums such as a djembe or a djun djun . but what they did have were plenty of shipping crates . not only were these readily accessible , but their inconspicuous appearance may have helped get around laws prohibiting slaves from playing music . early peruvian cajons consisted of a simple box with five thick wooden sides . the sixth side , made of a thinner sheet of wood , would be used as the striking surface , or more commonly known as the tapa . a sound hole was also cut into the back to allow the sound to escape . as an afro-peruvian culture developed , and new forms of music and dance , such as zamacueca , festejo and landó were born , the cajon became a dedicated musical instrument in its own right . early modifications involved simply bending the planks of the box to tweak the sound , and when abolition of slavery introduced the cajon to a broader population , more improvisation and experimentation soon followed . perhaps the person most responsible for introducing the cajon to european audiences was spanish flamenco guitarist paco de lucía . when touring in peru in 1977 , he and his percussionist rubem dantas discovered the cajon and brought it back to spain , recognizing its potential for use in flamenco music . by stretching guitar strings along the inside of the tapa , the flamenco musicians were able to create a buzz-like snare sound . combined with the regular base tone , this gave the cajon a sound close to a basic drum set . the cajon quickly caught on , not only becoming standard in flamenco , but being used in genres like folk , jazz , blues and rock . today , many specialized cajons are manufactured , some with adjustable strings , some with multiple playing surfaces , and some with a snare mechansim . but the basic concept remains the same , and the story of the cajon shows that the simplest things can have the most amazing potential when you think outside and inside the box .
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and this simplicity may be key to its journey across continents and cultures to become one of the most popular percussion instruments in the world today . the cajon 's story begins in west africa , whose indigenousness people had rich musical traditions centered on drumming and dancing . when many of them were captured and brought to the americas as slaves , they brought this culture with them , but without their native instruments , they had to improvise .
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where does the cajon 's story begin ?
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this is a map of yellowstone national park for the most part the park is in wyoming but it extends a bit into montana and idaho this little 50 square miles section in idaho is what concerns us it 's called the zone of death because of a loophole that exists in the constitution of the united states if someone were to exploit that loophole they might be able to get away with murder yellowstone was established in 1872 before wyoming idaho and montana join the union it 's federal land and always has been but federal land across the u.s. is split up and divided into its corresponding state district courts except for yellowstone and this is where the loophole begins law professor brian c. kalt points out in his 2005 paper the perfect crime that yellowstone national park was assigned fully to wyoming 's district court even though small portions fall into montana and idaho unlike every other district the district of wyoming includes land in other state so kalt asks the question what happens if you 're caught for a crime you committed in that 50 square mile idea who region of the park the first thing law enforcement would do is bring you to cheyenne the hub of the district court of wyoming because the crime technically happened within wyoming 's jurisdiction but article 3 section 2 of the united states constitution says that the trial should happen in the state where you committed the crime if you 're a savvy murderer you invoke your right to a trial in idaho so they bring you back to idaho no big deal in the sixth amendment they said that they would require local juries and the language they use is that the jury has to be from the state and district where the crime was committed this is called the vicinage clause that leaves you with a sort of venn diagram you have the right to demand jury from that middle area where the state in which you committed the crime that 's idaho overlaps with the judicial jurisdiction where you committed the crime the wyoming district that has jurisdiction over yellowstone national park and here 's the problem nobody lives there there 's there 's no way for them to give you a trial and so i argue they should have to let you go this could also happen in the montana portion of the park except a few dozen people do live there so a jury could theoretically be called kalt has proposed numerous solutions to congress to fix the loophole but they have yet to act all they have to do is redraw the district line so that the district of wyoming is wyoming the district of idaho is in idaho and the district of montana in montana and if they do that it all goes away so if you 're planning a gathering of your adversaries exes and debtors maybe try yosemite
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this is a map of yellowstone national park for the most part the park is in wyoming but it extends a bit into montana and idaho this little 50 square miles section in idaho is what concerns us it 's called the zone of death because of a loophole that exists in the constitution of the united states if someone were to exploit that loophole they might be able to get away with murder yellowstone was established in 1872 before wyoming idaho and montana join the union it 's federal land and always has been but federal land across the u.s. is split up and divided into its corresponding state district courts except for yellowstone and this is where the loophole begins law professor brian c. kalt points out in his 2005 paper the perfect crime that yellowstone national park was assigned fully to wyoming 's district court even though small portions fall into montana and idaho unlike every other district the district of wyoming includes land in other state so kalt asks the question what happens if you 're caught for a crime you committed in that 50 square mile idea who region of the park the first thing law enforcement would do is bring you to cheyenne the hub of the district court of wyoming because the crime technically happened within wyoming 's jurisdiction but article 3 section 2 of the united states constitution says that the trial should happen in the state where you committed the crime if you 're a savvy murderer you invoke your right to a trial in idaho so they bring you back to idaho no big deal in the sixth amendment they said that they would require local juries and the language they use is that the jury has to be from the state and district where the crime was committed this is called the vicinage clause that leaves you with a sort of venn diagram you have the right to demand jury from that middle area where the state in which you committed the crime that 's idaho overlaps with the judicial jurisdiction where you committed the crime the wyoming district that has jurisdiction over yellowstone national park and here 's the problem nobody lives there there 's there 's no way for them to give you a trial and so i argue they should have to let you go this could also happen in the montana portion of the park except a few dozen people do live there so a jury could theoretically be called kalt has proposed numerous solutions to congress to fix the loophole but they have yet to act all they have to do is redraw the district line so that the district of wyoming is wyoming the district of idaho is in idaho and the district of montana in montana and if they do that it all goes away so if you 're planning a gathering of your adversaries exes and debtors maybe try yosemite
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what would happen if you committed a crime in the “ zone of death ” ?
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is there a disease that makes us love cats , and do you have it ? maybe , and it 's more likely than you 'd think . we 're talking about toxoplasmosis , a disease caused by toxoplasma gondii . like all parasites , toxoplasma lives at the expense of its host , and needs its host to produce offspring . to do that , toxo orchestrates a brain manipulation scheme involving cats , their rodent prey , and virtually all other birds and mammals , including humans . documented human infections go as far back as ancient egypt . we found samples in mummies . today , about a third of the world 's population is infected , and most of them never even know it . in healthy people , symptoms often do n't show up at all . when they do , they 're mild and flu-like . but those are just the physical symptoms . toxoplasma also nestles into our brains and meddles with our behavior behind the scenes . to understand why , let 's take a look at the parasite 's life cycle . while the parasite can multiply in practically any host , it can only reproduce sexually in the intestines of cats . the offspring , called oocysts , are shed in the cat 's feces . a single cat can shed up to a hundred million oocysts . if another animal , like a mouse , accidentally ingests them , they 'll invade the mouse 's tissues and mature to form tissue cysts . if the mouse gets eaten by a cat , the tissue cysts become active and release offspring that mate to form new oocysts , completing the cycle . but there 's a problem . a mouse 's natural desire to avoid a cat makes it tough to close this loop . toxoplasma has a solution for that . the parasites invade white blood cells to hitch a ride to the brain where they seem to override the innate fear of predators . infected rodents are more reckless and have slower reaction times . strangest of all , they 're actually attracted to feline urine , which probably makes them more likely to cross paths with a cat and help the parasite complete its life cycle . how does the parasite pull this off ? although the exact mechanism is n't known , toxo appears to increase dopamine , a brain neurotransmitter that is involved in novelty-seeking behavior . thus , one idea is that toxo tinkers with neurotransmitters , the chemical signals that modulate emotions . the result ? fatal attraction . but mice are n't the only animals that end up with these parasites , and that 's where humans , and all of toxo 's other hosts , come in . we can accidentally ingest oocysts in contaminated water , or unwashed produce , or from playing in sandboxes , or cleaning out litter boxes . this is behind the common recommendation that pregnant women not change cat litter . toxo can cause serious birth defects . we can also get toxo from eating undercooked meat from other animals that picked up some oocysts . and it turns out that toxo can mess with our brains , too . studies have found connections between toxo and schizophrenia , biopolar disorder , obsessive compulsive disorder , and aggression . it also slows reactions and decreases concentration , which may be why one study found that people involved in traffic accidents were almost three times more likely to have toxoplasma . so is toxo manipulating our brains as an evolutionary strategy to get predatory cats to eat us ? or are our brains just similar enough to a rodent 's that the same neurological tricks that lure them in catch us in the net , too ? and is toxo the reason so many people love cats and keep them as pets ? well , the jury 's still out on that one . some recent studies even contradict the idea . regardless , toxoplasma has definitely benefited from humans to become one of the world 's most successful parasites . it 's not just our willingness to let cats on our dining room tables or in our beds . raising livestock and building cities which attract rodents has provided billions of new hosts , and you and your cat may be two of them .
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studies have found connections between toxo and schizophrenia , biopolar disorder , obsessive compulsive disorder , and aggression . it also slows reactions and decreases concentration , which may be why one study found that people involved in traffic accidents were almost three times more likely to have toxoplasma . so is toxo manipulating our brains as an evolutionary strategy to get predatory cats to eat us ?
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infection with toxoplasma is associated with an increased risk of traffic accidents . this could be due to the parasite causing a lack of concentration and increased reaction times . can you think of an experiment to confirm whether infection with toxoplasma truly increases the risk of accidents ?
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about 66 million years ago , something terrible happened to life on our planet . ecosystems were hit with a double blow as massive volcanic eruptions filled the atmosphere with carbon dioxide and an asteroid roughly the size of manhattan struck the earth . the dust from the impact reduced or stopped photosynthesis from many plants , starving herbivores and the carnivores that preyed on them . within a short time span , three-quarters of the world 's species disappeared forever , and the giant dinosaurs , flying pterosaurs , shelled squids , and marine reptiles that had flourished for ages faded into prehistory . it may seem like the dinosaurs were especially unlucky , but extinctions of various severities have occurred throughout the earth 's history , and are still happening all around us today . environments change , pushing some species out of their comfort zones while creating new opportunities for others . invasive species arrive in new habitats , outcompeting the natives . and in some cases , entire species are wiped out as a result of activity by better adapted organisms . sometimes , however , massive changes in the environment occur too quickly for most living creatures to adapt , causing thousands of species to die off in a geological instant . we call this a mass extinction event , and although such events may be rare , paleontologists have been able to identify several of them through dramatic changes in the fossil record , where lineages that persisted through several geological layers suddenly disappear . in fact , these mass extinctions are used to divide the earth 's history into distinct periods . although the disappearance of the dinosaurs is the best known mass extinction event , the largest occurred long before dinosaurs ever existed . 252 million years ago , between the permian and triassic periods , the earth 's land masses gathered together into the single supercontinent pangaea . as it coalesced , its interior was filled with deserts , while the single coastline eliminated many of the shallow tropical seas where biodiversity thrived . huge volcanic eruptions occurred across siberia , coinciding with very high temperatures , suggesting a massive greenhouse effect . these catastrophes contributed to the extinction of 95 % of species in the ocean , and on land , the strange reptiles of the permian gave way to the ancestors of the far more familiar dinosaurs we know today . but mass extinctions are not just a thing of the distant past . over the last few million years , the fluctuation of massive ice sheets at our planet 's poles has caused sea levels to rise and fall , changing weather patterns and ocean currents along the way . as the ice sheets spread , retreated , and returned , some animals were either able to adapt to the changes , or migrate to a more suitable environment . others , however , such as giant ground sloths , giant hyenas , and mammoths went extinct . the extinction of these large mammals coincides with changes in the climate and ecosystem due to the melting ice caps . but there is also an uncomfortable overlap with the rise of a certain hominid species originating in africa 150,000 years ago . in the course of their adaptation to the new environment , creating new tools and methods for gathering food and hunting prey , humans may not have single-handedly caused the extinction of these large animals , as some were able to coexist with us for thousands of years . but it 's clear that today , our tools and methods have become so effective that humans are no longer reacting to the environment , but are actively changing it . the extinction of species is a normal occurrence in the background of ecosystems . but studies suggest that rates of extinction today for many organisms are hundreds to thousands of times higher than the normal background . but the same unique ability that makes humans capable of driving mass extinctions can also enable us to prevent them . by learning about past extinction events , recognizing what is happening today as environments change , and using this knowledge to lessen our effect on other species , we can transform humanity 's impact on the world from something as destructive as a massive asteroid into a collaborative part of a biologically diverse future .
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these catastrophes contributed to the extinction of 95 % of species in the ocean , and on land , the strange reptiles of the permian gave way to the ancestors of the far more familiar dinosaurs we know today . but mass extinctions are not just a thing of the distant past . over the last few million years , the fluctuation of massive ice sheets at our planet 's poles has caused sea levels to rise and fall , changing weather patterns and ocean currents along the way .
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paleontologists have identified many possible causes of mass extinctions . which of these has not been identified by paleontologists as an agent of mass extinction ?
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berkelium which , i assume was named after the place of its discovery , which was berkeley and they made 3 billionths of a gram of it , which was just enough to record some spectroscopic data on it and prove that they had actually made it .
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berkelium which , i assume was named after the place of its discovery , which was berkeley and they made 3 billionths of a gram of it , which was just enough to record some spectroscopic data on it and prove that they had actually made it .
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berkelium was made the first time by bombarding 7 mg of pure americium-241 with helium . can you write the chemical equation for this reaction ?
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a famous ancient greek once said , `` give me a place to stand , and i shall move the earth . '' but this was n't some wizard claiming to perform impossible feats . it was the mathematician archimedes describing the fundamental principle behind the lever . the idea of a person moving such a huge mass on their own might sound like magic , but chances are you 've seen it in your everyday life . one of the best examples is something you might recognize from a childhood playground : a teeter-totter , or seesaw . let 's say you and a friend decide to hop on . if you both weigh about the same , you can totter back and forth pretty easily . but what happens if your friend weighs more ? suddenly , you 're stuck up in the air . fortunately , you probably know what to do . just move back on the seesaw , and down you go . this may seem simple and intuitive , but what you 're actually doing is using a lever to lift a weight that would otherwise be too heavy . this lever is one type of what we call simple machines , basic devices that reduce the amount of energy required for a task by cleverly applying the basic laws of physics . let 's take a look at how it works . every lever consists of three main components : the effort arm , the resistance arm , and the fulcrum . in this case , your weight is the effort force , while your friend 's weight provides the resistance force . what archimedes learned was that there is an important relationship between the magnitudes of these forces and their distances from the fulcrum . the lever is balanced when the product of the effort force and the length of the effort arm equals the product of the resistance force and the length of the resistance arm . this relies on one of the basic laws of physics , which states that work measured in joules is equal to force applied over a distance . a lever ca n't reduce the amount of work needed to lift something , but it does give you a trade-off . increase the distance and you can apply less force . rather than trying to lift an object directly , the lever makes the job easier by dispersing its weight across the entire length of the effort and resistance arms . so if your friend weighs twice as much as you , you 'd need to sit twice as far from the center as him in order to lift him . by the same token , his little sister , whose weight is only a quarter of yours , could lift you by sitting four times as far as you . seesaws may be fun , but the implications and possible uses of levers get much more impressive than that . with a big enough lever , you can lift some pretty heavy things . a person weighing 150 pounds , or 68 kilograms , could use a lever just 3.7 meters long to balance a smart car , or a ten meter lever to lift a 2.5 ton stone block , like the ones used to build the pyramids . if you wanted to lift the eiffel tower , your lever would have to be a bit longer , about 40.6 kilometers . and what about archimedes ' famous boast ? sure , it 's hypothetically possible . the earth weighs 6 x 10^24 kilograms , and the moon that 's about 384,400 kilometers away would make a great fulcrum . so all you 'd need to lift the earth is a lever with a length of about a quadrillion light years , 1.5 billion times the distance to the andromeda galaxy . and of course a place to stand so you can use it . so for such a simple machine , the lever is capable of some pretty amazing things . and the basic elements of levers and other simple machines are found all around us in the various instruments and tools that we , and even some other animals , use to increase our chances of survival , or just make our lives easier . after all , it 's the mathematical principles behind these devices that make the world go round .
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the idea of a person moving such a huge mass on their own might sound like magic , but chances are you 've seen it in your everyday life . one of the best examples is something you might recognize from a childhood playground : a teeter-totter , or seesaw . let 's say you and a friend decide to hop on .
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on a teeter-totter , unequal weights at equal distances will _____ .
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where does bread get its fluffiness ? swiss cheese its holes ? and what makes vinegar so sour ? these foods may taste completely different , but all of these phenomena come from tiny organisms chowing down on sugar and belching up some culinary byproducts . let 's start with yeast . yeast are single-celled fungi used to make bread , beer , and wine , among other products . yeast break down carbohydrates , like sugar , to get energy and the molecules they need to function . they have two different ways to do this : the oxygen-dependent , or aerobic , pathway , and the oxygen-independent , anaerobic pathway , which is also called fermentation . when you bake bread , yeast can use both pathways , but they normally prefer to start with the anaerobic process of fermentation . in this process , ethanol is produced in addition to co2 . no , bread is n't alcoholic . small amounts of alcohol that are secreted evaporate during baking . in the aerobic , or oxygen-dependent pathway , the yeast consume some of the sugar and produce carbon dioxide gas , or co2 , and water . in both processes , the co2 accumulates and creates tiny bubbles . these bubbles get trapped by gluten and create a sponge-like structure that gives the bread its soft texture . wine also relies on yeast . but a wine-making set-up keeps the oxygen levels low so that yeast consume sugar using fermentation , the anaerobic pathway . the process often starts with wild yeasts already hanging out on the grapes . but to get consistent results , most winemakers also add carefully selected strains of yeast that can tolerate high levels of alcohol . the yeast consume the sugar in the grape juice , and as the sugar level drops , the alcohol level rises . this does n't necessarily mean that sweeter wines have less alcohol . different types of grapes start with different amounts of sugar , and sugar can also be added . what happens to the carbon dioxide ? it just bubbles away through a vent . in carbonated alcoholic beverages , like champagne and beer , sealed containers are used in primary or secondary fermentation to keep the carbon dioxide in the bottle . wine also introduces us to our second type of food-producing microorganism : bacteria . a special strain of bacteria turns a tart compound in grape juice into softer tasting ones that are responsible for some of the flavors in red wines and chardonnays . another type of bacteria , called acetic acid bacteria , is n't so desirable in wine , but they have their function , too . if there 's oxygen around , these bacteria convert the ethanol in wine into , well , acetic acid . let this process continue and you 'll eventually get vinegar . bacteria are the key for cheese , too . to make cheese , milk is inoculated with bacteria . the bacteria gobble up the lactose , a kind of sugar , and produce lactic acid , along with many other chemicals . as the milk gets more and more acidic , its proteins start to aggregate and curdle . that 's why spoiled milk is clumpy . cheesemakers usually add an enzyme called rennet , naturally found inside of cows , goats , and some other mammals to help this process along . eventually , those little curdles turn into bigger curds , which are pressed to squeeze out the water , and create a firm cheese . different strains of bacteria make different kinds of cheese . for example , a species of bacteria that emits carbon dioxide is what gives swiss cheese its characteristic holes . some cheeses , brie and camembert , use another kind of microorganism , too : mold . so your kitchen functions as a sort of biotechnology lab manned by microorganisms that culture your cuisine . yogurt , soy sauce , sour cream , sauerkraut , kefir , kimchi , kombucha , cheddar , challah , pita , and naan . but maybe not all at the same dinner .
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in the aerobic , or oxygen-dependent pathway , the yeast consume some of the sugar and produce carbon dioxide gas , or co2 , and water . in both processes , the co2 accumulates and creates tiny bubbles . these bubbles get trapped by gluten and create a sponge-like structure that gives the bread its soft texture .
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all these dishes have a general concept behind them -- applying biological processes in order to make a product . can you think of everyday products outside the kitchen being made using biological processes ?
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every year , about 1,000 new words are added to the oxford english dictionary . where do they come from , and how do they make it into our everyday lives ? with over 170,000 words currently in use in the english language , it might seem we already have plenty . yet , as our world changes , new ideas and inventions spring forth , and science progresses , our existing words leave gaps in what we want to express and we fill those gaps in several ingenious , practical , and occasionally peculiar ways . one way is to absorb a word from another language . english has borrowed so many words over its history that nearly half of its vocabulary comes directly from other languages . sometimes , this is simply because the thing the word describes was borrowed itself . rome and france brought legal and religious concepts , like altar and jury , to medieval england , while trade brought crops and cuisine , like arabic coffee , italian spaghetti , and indian curry . but sometimes , another language has just the right word for a complex idea or emotion , like naïveté machismo , or schadenfreude . scientists also use classical languages to name new concepts . clone , for example , was derived from the ancient greek word for twig to describe creating a new plant from a piece of the old . and today , the process works both ways , with english lending words like software to languages all over the world . another popular way to fill a vocabulary gap is by combining existing words that each convey part of the new concept . this can be done by combining two whole words into a compound word , like airport or starfish , or by clipping and blending parts of words together , like spork , brunch , or internet . and unlike borrowings from other languages , these can often be understood the first time you hear them . and sometimes a new word is n't new at all . obsolete words gain new life by adopting new meanings . villain originally meant a peasant farmer , but in a twist of aristocratic snobbery came to mean someone not bound by the knightly code of chivalry and , therefore , a bad person . a geek went from being a carnival performer to any strange person to a specific type of awkward genius . and other times , words come to mean their opposite through irony , metaphor , or misuse , like when sick or wicked are used to describe something literally amazing . but if words can be formed in all these ways , why do some become mainstream while others fall out of use or never catch on in the first place ? sometimes , the answer is simple , as when scientists or companies give an official name to a new discovery or technology . and some countries have language academies to make the decisions . but for the most part , official sources like dictionaries only document current usage . new words do n't originate from above , but from ordinary people spreading words that hit the right combination of useful and catchy . take the word meme , coined in the 1970s by sociobiologist richard dawkins from the ancient greek for imitation . he used it to describe how ideas and symbols propagate through a culture like genes through a population . with the advent of the internet , the process became directly observable in how jokes and images were popularized at lightning speed . and soon , the word came to refer to a certain kind of image . so meme not only describes how words become part of language , the word is a meme itself . and there 's a word for this phenomenon of words that describe themselves : autological . not all new words are created equal . some stick around for millennia , some adapt to changing times , and others die off . some relay information , some interpret it , but the way these words are created and the journey they take to become part of our speech tells us a lot about our world and how we communicate within it .
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with the advent of the internet , the process became directly observable in how jokes and images were popularized at lightning speed . and soon , the word came to refer to a certain kind of image . so meme not only describes how words become part of language , the word is a meme itself . and there 's a word for this phenomenon of words that describe themselves : autological .
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the word meme came about through :
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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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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 ?
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in representing the binary system on fingers , a raised first digit has the value 1 , a raised second digit the value 2 , a raised third digit the value 4 , all the way up to a raised tenth digit having the value 512. what number is represented by raising the first , third , fifth , and sixth fingers together ?
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thousands of years in the making , what began as part of a religious festival honoring the greek god zeus in the rural greek town of olympia has today become the greatest show of sporting excellence on earth . the inception date in 776 bc became the basis for the greek 's earliest calendar , where time was marked in four-year increments called olympiads . what could it be ? why , it 's the olympic games , of course . competition fosters excellence , or so thought the ancient greeks . in addition to sporting events , contests were held for music , singing , and poetry . you can read about them all yourself in classical literary works , like homer 's `` iliad '' and virgil 's `` aeneid . '' even mythical heroes appreciate a good contest every now and then , would n't you say ? for the first thirteen games , the ancient greek olympics featured just one event , the two hundred yard dash . but over time , new exciting contests , like boxing , chariot and mule racing , and even a footrace where the competitors wore a full suit of armor enticed many hopeful champions into the olympic stadium . the combined running , jumping , wrestling , javelin throwing , and hurling the discus events known as the pentathlon inspired world-class competition , and the pankration , a no holds barred fight where only biting and eye-gouging were prohibited , ensured the toughest men were victorious . and victorious they were . nobody tops the local baker coroebus , who 776 bc became the very first olympic champion . and we 'll never forget orsippus of megara , the 720 bc olympic victor tore away his loincloth so he could race unimpeded , inaugurating the ancient greek tradition of competing in the nude . now there 's a winning streak , if ever we 've seen one . but all good things must end . in 391 ad , the christian roman emperor theodosius banned pagan practices , so the world soon bid a fond farewell to the olympic games . but just like those early pankration athletes , you ca n't keep a good one down , and 1500 years later in 1896 , the modern olympic games kicked off in athens , greece . today , the summer and winter olympics bring international world-class athletes together by the thousands , uniting fans by the billions for the world 's foremost sporting competition . citius , altius , fortius . three cheers for the olympics .
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even mythical heroes appreciate a good contest every now and then , would n't you say ? for the first thirteen games , the ancient greek olympics featured just one event , the two hundred yard dash . but over time , new exciting contests , like boxing , chariot and mule racing , and even a footrace where the competitors wore a full suit of armor enticed many hopeful champions into the olympic stadium .
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what was the profession of the first winner of the ancient olympics ?
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as 1905 dawned , the soon-to-be 26-year-old albert einstein faced life as a failed academic . most physicists of the time would have scoffed at the idea that this minor civil servant could have much to contribute to science . yet within the following year , einstein would publish not one , not two , not three , but four extraordinary papers , each on a different topic , that were destined to radically transform our understanding of the universe . the myth that einstein had failed math is just that . he had mastered calculus on his own by the age of 15 and done well at both his munich secondary school and at the swiss polytechnic , where he studied for a math and physics teaching diploma . but skipping classes to spend more time in the lab and neglecting to show proper deference to his professors had derailed his intended career path . passed over even for a lab assistant position , he had to settle for a job at the swiss patent office , obtained with the help of a friend 's father . working six days a week as a patent clerk , einstein still managed to make some time for physics , discussing the latest work with a few close friends , and publishing a couple of minor papers . it came as a major surprise when in march 1905 he submitted a paper with a shocking hypothesis . despite decades of evidence that light was a wave , einstein proposed that it could , in fact , be a particle , showing that mysterious phenomena , such as the photoelectric effect , could be explained by his hypothesis . the idea was derided for years to come , but einstein was simply twenty years ahead of his time . wave-particle duality was slated to become a cornerstone of the quantum revolution . two months later in may , einstein submitted a second paper , this time tackling the centuries old question of whether atoms actually exist . though certain theories were built on the idea of invisible atoms , some prominent scientists still believed them to be a useful fiction , rather than actual physical objects . but einstein used an ingenious argument , showing that the behavior of small particles randomly moving around in a liquid , known as brownian motion , could be precisely predicted by the collisions of millions of invisible atoms . experiments soon confirmed einstein 's model , and atomic skeptics threw in the towel . the third paper came in june . for a long time , einstein had been troubled by an inconsistency between two fundamental principles of physics . the well established principle of relativity , going all the way back to galileo , stated that absolute motion could not be defined . yet electromagnetic theory , also well established , asserted that absolute motion did exist . the discrepancy , and his inability to resolve it , left einstein in what he described as a state of psychic tension . but one day in may , after he had mulled over the puzzle with his friend michele besso , the clouds parted . einstein realized that the contradiction could be resolved if it was the speed of light that remained constant , regardless of reference frame , while both time and space were relative to the observer . it took einstein only a few weeks to work out the details and formulate what came to be known as special relativity . the theory not only shattered our previous understanding of reality but would also pave the way for technologies , ranging from particle accelerators , to the global positioning system . one might think that this was enough , but in september , a fourth paper arrived as a `` by the way '' follow-up to the special relativity paper . einstein had thought a little bit more about his theory , and realized it also implied that mass and energy , one apparently solid and the other supposedly ethereal , were actually equivalent . and their relationship could be expressed in what was to become the most famous and consequential equation in history : e=mc^2 . einstein would not become a world famous icon for nearly another fifteen years . it was only after his later general theory of relativity was confirmed in 1919 by measuring the bending of starlight during a solar eclipse that the press would turn him into a celebrity . but even if he had disappeared back into the patent office and accomplished nothing else after 1905 , those four papers of his miracle year would have remained the gold standard of startling unexpected genius .
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most physicists of the time would have scoffed at the idea that this minor civil servant could have much to contribute to science . yet within the following year , einstein would publish not one , not two , not three , but four extraordinary papers , each on a different topic , that were destined to radically transform our understanding of the universe . the myth that einstein had failed math is just that .
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of einstein ’ s four “ miracle year ” papers , which do you find most interesting and why ? which topic would you like to learn more about ?
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who does n't like birthday cakes ? and what i 'm going to show you today is that there are good ways and there are bad ways of cutting a cake . and the classic way , the bad way , is like this , which would be normal . you put the knife in the center . one bit of a slice , other bit of a slice ... [ laughter ] < i > brady haran : it 's like the classic . alex bellos : it is the classic . is n't it ? < /i > it 's almost like a pie chart . you know , one thing about the word pie chart . in france they call them camembert , which is like a cheese . it 's actually like a cheese chart in france . interesting cultural differences in math speak . so this is what you would do . you take this , you would put this over here , you eat it , and then you leave this in the fridge overnight . and the reason why this is a really bad way of cutting a cake is that these bits here are just going to get dry . so when you come the following day to have your cake , you know , you do another one , another slice like this this side here , hmm , lovely and soft this will be dry and horrible . you know , maximizing the amount of gastronomic pleasure that you can make out of this cake . there is a better way , a way that is more than a hundred years old and was discovered or invented by one of britain 's most famous and brilliant mathematical scientists . this is a copy of nature , the famous science magazine , from december the 20th 1906 . and in the letters to the editor here it says : the headline : cutting a round cake on scientific principles . `` the ordinary method of cutting out a wedge '' , he writes , `` is very faulty '' . what he suggests is , and he gives an illustration for it , the proper way , the scientific way , the mathematically perfect way of cutting a round cake and it is as follows . so we have another cake the first slice will be like this . breaking all the rules of a cake etiquette . perfect . ok ? so this is the first one , and then i need to find a way of ... taking it out ... ok. we can stick that there . and that is got to be the prime steak of that cake . is n't it ? it 's the t-bone cut . here 's what we need to do ... we need to close the cake together , like this . and it 's going to come apart , so look what i 've got here ... i have got some rubber bands to make sure it stays together . the following day ... all the flesh , the sponge is going to be nice and soft . so , how do we do the second slice ? the second slice ... i guess it 's not your birthday anymore , so you 're not going to have one quite as big ... it will be interesting to work out the actual proportions . this is ... you get a lovely break in the elastic bands too , which is exciting . this is slice two . or , it actually is slice two which has two slices , two parts . so you put this back together . and we can keep on going . obviously , i 'm going to want to use the elastic band to put the cake ... yeah , that is perfect . that is going to stay so fresh for day three . day three . brady haran : actually do day three , gab . alex bellos : let 's turn it around . i think this is going to be the slice for day three . again , the satisfying snap of the elastic bands ... and ... i do n't know if you thought about if before , but these triangular slices are really annoying anyway , because ... it 's not very satisfying . having a nice uniform slice like that is a lot better . so , here we go again ... at the end of day three ... this is for ... and this is going to be perfect . and gradually we are slicing it , keep on going . i think for the mathematical loners who do n't want to share their cakes it could be useful . brady haran : for a bit more of this interview including more about the guy that came up with this cake cutting method have a look at the extra footage over numberphile 2 . and if you just like to hear more great stories from alex , he 's got a new book out just recently : `` alex through the looking glass - how life reflects numbers and numbers reflect life '' . it 's really good . it 's also just out in the us , but it has a different name in the us . it 's called `` the grapes of math '' . i 'll put links to it in the video description .
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and what i 'm going to show you today is that there are good ways and there are bad ways of cutting a cake . and the classic way , the bad way , is like this , which would be normal . you put the knife in the center .
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why is the classic way of cutting a cake a bad way to cut a cake ?
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have you ever walked into a grocery store and wondered where all those variety of apples came from ? you might find snapdragon , pixie crunch , cosmic crisp , jazz , or ambrosia next to the more familiar red delicious and granny smith . these delightfully descriptive names belong to just a handful of the over 7,500 apple varieties in the world . this huge diversity exists largely because of humanity 's efforts to bear new fruit . fruit breeding is a way to fulfill the expectations of farmers and consumers who seek specific qualities in an apple . on the one hand , farmers may want them to be disease-resistant and to store well . on the other , consumers are swayed by appearance , taste , and novelty . so , breeders have to consider everything from how well apples grow in certain climates to their color , taste , and size . and sometimes finding the perfect fit means breeding something new . to create apples with desirable characteristics , breeders first need to find parent apples that carry those characteristics . once the parents have been selected , they have to wait until the trees bloom in the spring . the breeder takes the pollen from one bloom , called the father , and transfers it by hand to the other parent bloom , called the mother , through a process called cross-pollination . once the mother bloom turns into an apple , the seeds are collected and then planted . it takes about five years for these seeds to grow into trees that produce apples , but because of the way traits are inherited , all of the seedlings produced will have different sets of genes and characteristics . this means that to achieve a desired quality , it takes a lot of offspring , not to mention patience on the breeder 's part . when a seedling does bear fruit with the desired qualities , it 's selected for further evaluation . of the original crossed seedlings , about one in every 5,000 makes it to this prestigious stage . they 're then sent to new farms where breeders can assess how various climates and soil types affect the plant 's growth . the fruit of the seedling and its many clones must then be collected and sampled to ensure consistency . breeders study about 45 traits in an apple , like the texture and firmness of the flesh , when it ripens , how sugary its juice is , and how long it stays fresh . over several years , they weed out all the bad apples , selecting only those whose fruits are the best . these exclusive plants officially form the cultivar , or new apple variety . to ensure an exact copy of this cultivar , all apple trees must be grafted from the original seedling . branches , called scion wood , are cut from the original tree and grown to generate more scion wood . segments of these trees are then grafted onto root stalk - that 's the lower section of another tree that 's been chosen from a different cultivar for its superior roots and growing ability . finally , this fusion creates a new apple tree with the desired qualities . each new plant takes up to four years before it starts producing the fruit we eat . apple breeding may be a difficult art , but it 's accessible to all : universities , companies , and even individuals can create new cultivars . but to fully own an apple , the breeder faces a final challenge - naming the fruit . after a cultivar is patented , a breeder chooses a name for its trademark . that final step grants them long-lasting rights over the apple and its clones . that name must be completely original , and the catchier , the better , of course . with over 7,500 varieties and counting , that 's why we have apples called pink lady , sweet tango , kiku , and evercrisp . the more we work with nature 's bounty to breed new cultivars , the more creative and delectable these names will become .
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segments of these trees are then grafted onto root stalk - that 's the lower section of another tree that 's been chosen from a different cultivar for its superior roots and growing ability . finally , this fusion creates a new apple tree with the desired qualities . each new plant takes up to four years before it starts producing the fruit we eat .
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the way to create a copy of a desired apple tree is to :
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one day the universe will die . but why ? and how ? and will the universe be dead forever ? and how do we know that ? first of all , the universe is expanding . and not only that , the rate of its expansion is accelerating . the reason : dark energy . dark energy is a strange phenomenon that scientists believe permeates the universe . until 1998 we thought that the universe must work a bit like a ball that you throw into the sky . the ball moves up , but at some point it has to come down again . but the expansion of the universe is actually speeding up . that ’ s like throwing a ball up and watching it fly away faster and faster and faster . where is this acceleration coming from ? well , we don ’ t know , but we call it “ dark energy ” . einstein thought of it first and then decided it was stupid . now , astrophysicists have decided it is plausible . trouble is , this is all very theoretical , and we don ’ t actually know what the properties of dark energy are . but there are various theories and they lead us to three scenarios for the end of the universe . one : the big rip . since its birth , the universe has been expanding . for unknown reasons new spaces created everywhere equally . the space between galaxies expands , so they move apart . the space inside galaxies also expands , but here , gravity is strong enough to keep them together . in the big rip scenario , the expansion accelerates up to a point where space expands so fast that gravity can ’ t compensate for this effect anymore . the result is a big rip . at first , only large structures like galaxies are torn apart , since space between the single objects expands very fast . next , big bodies like black holes , stars , and planets die . their gravity isn ’ t strong enough to keep them together , so they dissolve into their components . in the end , space would expand faster than the speed of light . atoms would now be affected , and they would just disband . once space is expanding faster than light , no particle in the universe can interact with any other particle anymore . the universe would dissolve into countless lonely particles that won ’ t be able to touch anything else in a strange , timeless universe . hmm , and you thought you felt lonely ! two : heat death or a big freeze . in a nutshell , the difference between the big rip and heat death is that in a heat death scenario matter stays intact and is converted over an incredibly long but finite period of time into radiation , while the universe expands forever . but how does this work ? let ’ s talk about entropy . every system tends towards the state of highest entropy , like when we have a latte macchiato . initially , it has different regions , but over time , they will cool down and disintegrate , until it ’ s uniform . and this also applies to the universe . so , while the universe gets bigger and bigger , matters slowly decays and spreads out . at some point , after lots of generations of stars , all the gas clouds necessary to form stars will be exhausted , so the universe will turn dark . the remaining suns will die ; black holes will slowly degenerate and evaporate over trillions of years due to what ’ s known as hawking radiation . when this process is complete , only a dilute gas of photons and light particles remains , until even this decays . all activity in the universe ceases at this point ; entropy is at its maximum and the universe is dead forever . unless… theoretically , it might be possible that after an incredibly long amount of time , there might be a spontaneous entropy decrease as a result of something called “ quantum tunneling ” , leading to a new big bang . three : big crunch and big bounce . this is the most uplifting scenario . if there is less dark energy than we think or it decreases over time , gravity will be the dominating force in the universe one day . in a few trillion years , the rate of expansion of the universe will slow down and stop . after that , it reverses . galaxies will race at each other , merging as the universe becomes smaller and smaller . since a smaller universe also means a hotter universe , temperatures rise everywhere all at once . one hundred thousand years before the big crunch , background radiation would be hotter than the surfaces of the most stars , which means that they would be cooked from the outside . minutes before the big crunch happens , atom cores are ripped apart , before supermassive black holes devour everything . finally , all black holes would emerge into a supermassive mega-black hole that contains the entire mass of the universe , and in the last moment before the big crunch it would devour the universe , including itself . the big bounce theory states that this has happened a lot of times and that the universe goes through an infinite cycle of expansion and contraction . well , wouldn ’ t that be nice ? so what will actually happen to the universe in the end ? at the moment , heat death seems the most likely , but we at kurzgesagt hope that this “ dead forever ” stuff is wrong and the universe will start over and over again . we do n't know for sure either way , so let ’ s just assume the most uplifting theory is true . by the way , we have a twitter account . subtitles by the amara.org community
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well , wouldn ’ t that be nice ? so what will actually happen to the universe in the end ? at the moment , heat death seems the most likely , but we at kurzgesagt hope that this “ dead forever ” stuff is wrong and the universe will start over and over again .
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which is the most promising end of the universe scenario ?
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do you remember when you first realized that your computer was more than just a monitor and keyboard ? that between the mouse click and the video playing , there was something that captured your intention , understood it , and made it real ? what is that something ? is it gremlins ? let 's imagine that we can shrink down to the size of an electron and inject ourselves into a click of a mouse . if you took your mouse apart , you 'd see that it 's really a very simple machine . it has a couple buttons and a system for detecting motion and distance . you might have an optical mouse that makes these measurements with lights and sensors , but older ones did this with a hard rubber ball and some plastic wheels . same concept . when you click the button on your mouse , it sends a message to the computer with information about its position . when your mouse click is received , it 's handled by the basic input/output subsystem . this subsystem acts like the eyes and ears and mouth and hands of the computer . basically , it provides a way for the computer to interact with its environment . but it also acts like a buffer to keep the cpu from being overwhelmed by distractions . in this case , the i/o subsystem decides that your mouse click is pretty important so it generates an interrupt to the cpu . `` hey , cpu ! got a click here . '' the cpu , or central processing unit , is the brains of the whole computer . just like your brain does n't take up your whole body , the cpu does n't take up the whole computer , but it runs the show all the same . and the cpu 's job , its whole job , is fetching instructions from memory and executing them . so , while you 're typing , typing , typing , maybe really fast , like 60 words a minute , the cpu is fetching and executing billions of instructions a second . yes , billions every second : instructions to move your mouse around on the screen , to run that clock widget on your desktop , play your internet radio , manage the files you 're editing on the hard drive , and much , much more . your computer 's cpu is one heck of a multitasker ! `` but oh my gosh there 's a very important mouse click coming through now ! let 's drop everything now and deal with that ! '' there are programs for everything that the cpu does . a special program for the mouse , for the clock widget , for the internet radio , and for dealing with letters sent by the keyboard . each program was initially written by a human in a human-readable programming language , like java , c++ , or python . but human programs take up a lot of space and contain a lot of unnecessary information to a computer , so they are compiled and made smaller and stored in bits of ones and zeros in memory . the cpu realizes that it needs instructions for how to deal with this mouse click , so it looks up the address for the mouse program and sends a request to the memory subsystem for instructions stored there . each instruction in the mouse device driver is duly fetched and executed . and that 's not nearly the end of the story ! because the cpu learns that the mouse was clicked when the cursor was over a picture of a button on the monitor screen , and so , the cpu asks memory for the monitor program to find out what that button is . and then the cpu has to ask memory for the program for the button , which means that the cpu needs the monitor program again to show the video associated with the button , and so it goes . and let 's just say there are a lot of programs involved before you even see the button on the screen light up when you clicked it . so , just the simple task of clicking your mouse means visiting all of the critical components of your computer 's architecture : peripherals , the basic input-output system , the cpu , programs , and memory , and not one gremlin .
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each program was initially written by a human in a human-readable programming language , like java , c++ , or python . but human programs take up a lot of space and contain a lot of unnecessary information to a computer , so they are compiled and made smaller and stored in bits of ones and zeros in memory . the cpu realizes that it needs instructions for how to deal with this mouse click , so it looks up the address for the mouse program and sends a request to the memory subsystem for instructions stored there .
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programs are encoded and stored in memory as
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did you know that every time musicians pick up their instruments , there are fireworks going off all over their brain ? on the outside , they may look calm and focused , reading the music and making the precise and practiced movements required . but inside their brains , there 's a party going on . how do we know this ? well , in the last few decades , neuroscientists have made enormous breakthroughs in understanding how our brains work by monitoring them in real time with instruments like fmri and pet scanners . when people are hooked up to these machines , tasks , such as reading or doing math problems , each have corresponding areas of the brain where activity can be observed . but when researchers got the participants to listen to music , they saw fireworks . multiple areas of their brains were lighting up at once , as they processed the sound , took it apart to understand elements like melody and rhythm , and then put it all back together into unified musical experience . and our brains do all this work in the split second between when we first hear the music and when our foot starts to tap along . but when scientists turned from observing the brains of music listeners to those of musicians , the little backyard fireworks became a jubilee . it turns out that while listening to music engages the brain in some pretty interesting activities , playing music is the brain 's equivalent of a full-body workout . the neuroscientists saw multiple areas of the brain light up , simultaneously processing different information in intricate , interrelated , and astonishingly fast sequences . but what is it about making music that sets the brain alight ? the research is still fairly new , but neuroscientists have a pretty good idea . playing a musical instrument engages practically every area of the brain at once , especially the visual , auditory , and motor cortices . as with any other workout , disciplined , structured practice in playing music strengthens those brain functions , allowing us to apply that strength to other activities . the most obvious difference between listening to music and playing it is that the latter requires fine motor skills , which are controlled in both hemispheres of the brain . it also combines the linguistic and mathematical precision , in which the left hemisphere is more involved , with the novel and creative content that the right excels in . for these reasons , playing music has been found to increase the volume and activity in the brain 's corpus callosum , the bridge between the two hemispheres , allowing messages to get across the brain faster and through more diverse routes . this may allow musicians to solve problems more effectively and creatively , in both academic and social settings . because making music also involves crafting and understanding its emotional content and message , musicians often have higher levels of executive function , a category of interlinked tasks that includes planning , strategizing , and attention to detail and requires simultaneous analysis of both cognitive and emotional aspects . this ability also has an impact on how our memory systems work . and , indeed , musicians exhibit enhanced memory functions , creating , storing , and retrieving memories more quickly and efficiently . studies have found that musicians appear to use their highly connected brains to give each memory multiple tags , such as a conceptual tag , an emotional tag , an audio tag , and a contextual tag , like a good internet search engine . how do we know that all these benefits are unique to music , as opposed to , say , sports or painting ? or could it be that people who go into music were already smarter to begin with ? neuroscientists have explored these issues , but so far , they have found that the artistic and aesthetic aspects of learning to play a musical instrument are different from any other activity studied , including other arts . and several randomized studies of participants , who showed the same levels of cognitive function and neural processing at the start , found that those who were exposed to a period of music learning showed enhancement in multiple brain areas , compared to the others . this recent research about the mental benefits of playing music has advanced our understanding of mental function , revealing the inner rhythms and complex interplay that make up the amazing orchestra of our brain .
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did you know that every time musicians pick up their instruments , there are fireworks going off all over their brain ? on the outside , they may look calm and focused , reading the music and making the precise and practiced movements required .
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neuroscientists get excited about watching the brain functions of musicians because ?
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there 's a play so powerful that an old superstition says its name should never even be uttered in a theater , a play that begins with witchcraft and ends with a bloody severed head , a play filled with riddles , prophesies , nightmare visions , and lots of brutal murder , a play by william shakespeare sometimes referred to as the `` scottish play '' or the `` tragedy of macbeth . '' first performed at the globe theater in london in 1606 , `` macbeth '' is shakespeare 's shortest tragedy . it is also one of his most action-packed . in five acts , he recounts a story of a scottish nobleman who steals the throne , presides over a reign of terror , and then meets a bloody end . along the way , it asks important questions about ambition , power , and violence that spoke directly to the politics of shakespeare 's time and continue to echo in our own . england in the early 17th century was politically precarious . queen elizabeth i died in 1603 without producing an heir , and in a surprise move , her advisors passed the crown to james stewart , king of scotland . two years later , james was subject to an assassination attempt called the gunpowder plot . questions of what made for a legitimate king were on everyone 's lips . so shakespeare must have known he had potent material when he conflated and adapted the stories of a murderous 11th century scottish king named macbeth and those of several other scottish nobles . he found their annals in hollinshed 's `` chronicles , '' a popular 16th century history of britain and ireland . shakespeare would also have known he needed to tell his story in a way that would immediately grab the attention of his diverse and rowdy audience . the globe welcomed all sections of society . wealthier patrons watched the stage from covered balconies while poorer people paid a penny to take in the show from an open-air section called the pit . talking , jeering , and cheering was common during performances . there are even accounts of audiences throwing furniture when plays were flops . so `` macbeth '' opens with a literal bang . thunder cracks and three witches appear . they announce they 're searching for a scottish nobleman and war hero named macbeth , then fly off while chanting a curse that predicts a world gone mad . `` fair is foul and foul is fair . hover through the fog and filthy air . '' as seen later , they find macbeth and his fellow nobleman banquo . `` all hail macbeth , '' they prophesize , `` that shalt be king hereafter ! '' `` king ? '' macbeth wonders . just what would he have to do to gain the crown ? macbeth and his wife lady macbeth soon chart a course of murder , lies , and betrayal . in the ensuing bloodbath , shakespeare provides viewers with some of the most memorable passages in english literature . `` out , damned spot ! out , i say ! '' lady macbeth cries when she believes she ca n't wipe her victim 's blood off her hands . her obsession with guilt is one of many themes that runs through the play , along with the universal tendency to abuse power , the endless cycles of violence and betrayal , the defying political conflict . as is typical with shakespeare 's language , a number of phrases that got their start in the play have been repeated so many times that they now feel commonplace . they include `` the milk of human kindness , '' `` what 's done is done , '' and the famous witches ' spell , `` double , double toil and trouble ; fire burn , and caldron bubble . '' but shakespeare saves the juiciest bit of all for macbeth himself . towards the end of the play , macbeth reflects on the universality of death and the futility of life . `` out , out , brief candle ! '' he laments . `` life 's but a walking shadow , a poor player that struts and frets his hour upon the stage and then is heard no more . it is a tale told by an idiot , full of sound and fury signifying nothing . '' life may be a tale told my an idiot , but `` macbeth '' is not . shakespeare 's language and characters have entered our cultural consciousness to a rare extent . directors often use the story to shed light on abuses of power , ranging from the american mafia to dictators across the globe . the play has been adapted to film many times , including akira kurosawa 's `` throne of blood , '' which takes place in feudal japan , and a modernized version called `` scotland , pa , '' in which macbeth and his rivals are managers of competing fast food restaurants . no matter the presentation , questions of morality , politics , and power are still relevant today , and so , it seems , is shakespeare 's `` macbeth . ''
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`` king ? '' macbeth wonders . just what would he have to do to gain the crown ?
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what are some ways director throughout history have adapted `` macbeth '' ?
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we 've all seen the movies where a monster , created by a scientist in a laboratory , escapes to wreak havoc on the outside world . but what if the monster was not some giant rampaging beast , destroying a city , but just a tiny amount of seaweed with the potential to disrupt entire coastal ecosystems ? this is the story of caulerpa taxifolia , originally a naturally occurring seaweed native to tropical waters . in the 1980s , one strain was found to thrive in colder environments . this trait , combined with its beautiful , bright green color and ability to grow quickly without maintenance made it ideal for aquariums , which it helped keep clean by consuming nutrients and chemicals in the water . further selective breeding made it even heartier , and soon it was used in aquariums around the world . but it was not long before a sample of this aquarium-developed super algae turned up in the mediterranean sea near the famed oceanographic museum of monaco . the marine biologist who found it believed that the museum had accidentally realeased it into the ocean along with aquarium waters , while museum directors claimed it had be carried into the area by ocean currents . regardless of how it ended up there , the non-native caulerpa multiplied rapidly , having no natural predators due to releasing a toxin that keeps fish away . and like some mythical monster , even a tiny piece that broke off could grow into a whole new colony . through water currents and contact with boat anchors and fishing lines , it fragmented and spread throughout mediterranean coastal cities covering coral reefs . so what was the result of this invasion ? well , it depends on who you ask . many scientists warned that the spread of caulerpa reduces biodiversity by crowding out native species of seaweed that are eaten by fish , with the biologist who first discovered its presence dubbing it killer algae . other studies instead claim that the algae actually had a beneficial effect by consuming chemical pollutants -- one reason the aquariums strain was developed . but the disruption of a natural ecosystem by an introduced foreign species can have unpredictable and uncontrollable effects that may not be immediately visible . so when culerpa taxifolia was discovered at carlsbad 's agua hedionda lagoon , near san diego in the year 2000 , having most likely come from the dumping of home aquarium water into a connecting storm drain , it was decided to stop it before it spread . tarps were placed over the culerpa colonies and chlorine injected inside . although this method killed all other marine life trapped under the tarps , it did succeed in eradicating the algae and native eelgrass was able to emerge in its place . by responding quickly , authorities in california were able to prevent culerpa from propagating . but another occurrence of the strain , in the coastal wetlands of southeast australia , was left unchecked and allowed to spread . and unfortunately , a tarp can not cover the mediterranean sea or the australian coast . invasive species are not a new problem , and can indeed occur naturally . but when such species are the results of human directed selective breeding or genetic modification and then released into the natural environment , their effect on ecosystems can be far more radical and irreversible . with the proliferation of new technologies and multiple threats to the environment , it is more important than ever for scientists to monitor and evaluate the risks and dangers , and for the rest of us to remember that what starts in our backyard can effect ecosystems half a world away .
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the marine biologist who found it believed that the museum had accidentally realeased it into the ocean along with aquarium waters , while museum directors claimed it had be carried into the area by ocean currents . regardless of how it ended up there , the non-native caulerpa multiplied rapidly , having no natural predators due to releasing a toxin that keeps fish away . and like some mythical monster , even a tiny piece that broke off could grow into a whole new colony .
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the native version of caulerpa grows in tropical waters around the world , and fish eat it to keep environmental balance ; the aquarium strain releases a toxin that keeps fish away . the strain of caulerpa that was developed in a laboratory though genetic modification and selective breeding was done to use it as :
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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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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 .
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what mathematician incorrectly boasted that none of his work would ever serve a useful purpose ?
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they 're everywhere , but you will never see one . trillions of them are flying through you right this second , but you ca n't feel them . these ghost particles are called neutrinos and if we can catch them , they can tell us about the furthest reaches and most extreme environments of the universe . neutrinos are elementary particles , meaning that they ca n't be subdivided into other particles the way atoms can . elementary particles are the smallest known building blocks of everything in the universe , and the neutrino is one of the smallest of the small . a million times less massive than an electron , neutrinos fly easily through matter , unaffected by magnetic fields . in fact , they hardly ever interact with anything . that means that they can travel through the universe in a straight line for millions , or even billions , of years , safely carrying information about where they came from . so where do they come from ? pretty much everywhere . they 're produced in your body from the radioactive decay of potassium . cosmic rays hitting atoms in the earth 's atmosphere create showers of them . they 're produced by nuclear reactions inside the sun and by radioactive decay inside the earth . and we can generate them in nuclear reactors and particle accelerators . but the highest energy neutrinos are born far out in space in environments that we know very little about . something out there , maybe supermassive black holes , or maybe some cosmic dynamo we 've yet to discover , accelerates cosmic rays to energies over a million times greater than anything human-built accelerators have achieved . these cosmic rays , most of which are protons , interact violently with the matter and radiation around them , producing high-energy neutrinos , which propagate out like cosmic breadcrumbs that can tell us about the locations and interiors of the universe 's most powerful cosmic engines . that is , if we can catch them . neutrinos ' limited interactions with other matter might make them great messengers , but it also makes them extremely hard to detect . one way to do so is to put a huge volume of pure transparent material in their path and wait for a neutrino to reveal itself by colliding with the nucleus of an atom . that 's what 's happening in antarctica at icecube , the world 's largest neutrino telescope . it 's set up within a cubic kilometer of ice that has been purified by the pressure of thousands of years of accumulated ice and snow , to the point where it 's one of the clearest solids on earth . and even though it 's shot through with boreholes holding over 5,000 detectors , most of the cosmic neutrinos racing through icecube will never leave a trace . but about ten times a year , a single high-energy neutrino collides with a molecule of ice , shooting off sparks of charged subatomic particles that travel faster through the ice than light does . in a similar way to how a jet that exceeds the speed of sound produces a sonic boom , these superluminal charged particles leave behind a cone of blue light , kind of a photonic boom . this light spreads through icecube , hitting some of its detectors located over a mile beneath the surface . photomultiplier tubes amplify the signal , which contains information about the charged particles ' paths and energies . the data are beamed to astrophysicists around the world who look at the patterns of light for clues about the neutrinos that produced them . these super energetic collisions are so rare that icecube 's scientists give each neutrino nicknames , like big bird and dr. strangepork . icecube has already observed the highest energy cosmic neutrinos ever seen . the neutrinos it detects should finally tell us where cosmic rays come from and how they reached such extreme energies . light , from infrared , to x-rays , to gamma rays , has given us increasingly energetic and continuously surprising views of the universe . we are now at the dawn of the age of neutrino astronomy , and we have no idea what revelations icecube and other neutrino telescopes may bring us about the universe 's most violent , most energetic phenomena .
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that is , if we can catch them . neutrinos ' limited interactions with other matter might make them great messengers , but it also makes them extremely hard to detect . one way to do so is to put a huge volume of pure transparent material in their path and wait for a neutrino to reveal itself by colliding with the nucleus of an atom .
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why do you think neutrinos are so hard to detect ?
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what is love ? seriously , though , what is it ? what is love ? a verb ? a noun ? a universal truth ? an ideal ? a common thread of all religions ? a cult ? a neurological phenomenon ? there 's no shortage of answers . some are all-encompassing . it conquers all . it 's all you need . it 's all there is . these are all comparisons , though , ways of defining it by contrast , by saying it 's more important than all other things , but is it ? sure , love matters more than your standard turkey sandwich , but does it matter more than shelter ? or sanity ? or an exceptional turkey sandwich ? no matter your answer , you 're just ranking it , not defining it . another challenge to defining love is we often try to do so while falling into it or out of it . would you trust someone who just won the lottery to accurately define the concept of currency ? or , i do n't know , ask a guy to define bears while he 's fending them off ? or is romance not like winning the lottery ? are break ups not like bear attacks ? bad comparisons ? that 's my point . i 'm not thinking right because i 'm in love , so ha ! taking a step back , or taking a cold shower , whatever , love is potentially the most intensely thought about thing in all of human history . and despite centuries upon centuries of obsession , it still overwhelms us . some say it 's a feeling , a magical emotion , a feeling for someone like you 've never felt before . but feelings are fluid , not very concrete foundation for a definition . sometimes you hate the person you love . plus , come on , you 've felt feelings like it before , sort of in miniature . your relationships with your family shape your relationships with partners . and your love for your partner may be in its own dynamic relationship , healthy or totally weird , with the love of your parents and siblings . love is also a set of behaviors we associate with the feeling : holding hands , kissing , hugging , public displays of affection , dating , marriage , having kids , or just sex . but these loving actions can be subjective or culturally relative . you may love or be someone who ca n't have kids or does n't want to , who believes in marriage but also in divorce , who 's from a culture where people do n't really date the way we think of dating , or who just does n't want to make out on the bus . but if love is a thing that we can define , then how can it mean opposite things for so many people ? so , maybe love 's just all in your head , a personal mystery winding through your neural pathways and lighting up pleasing , natural rewards in your nervous system . perhaps these rewards are addictive . perhaps love is a temporary or permanent addiction to a person , just like a person can be addicted to a drug . i do n't mean to be edgy like some pop song . evidence shows that chemicals in your brain stimulated by another person can make you develop a habit for that person . the person comes to satisfy a physiological craving , and you want more . but then sometimes , slowly or suddenly , you do n't . you 've fallen out of love , become unaddicted , for a spell . what happened ? does one develop a tolerance or hit a limit ? why do some lovers stay addicted to each other their entire lives ? perhaps to create new lives , to proliferate their species ? maybe love is just human dna 's optimal method for bringing about its own replication . there are evolutionary arguments regarding every human mating behavior , from how we display ourselves to potential mates , to how we treat each other in relationships , to how we raise kids . thus , some argue that the feeling you think you feel in your soul is just biology 's way to make you continue our species . nature has selected you to have crushes on hotties , just like it makes monkeys have crushes on hot monkeys , and biology marches on . but is that all love is ? or , perhaps worse , is it just a construct , some fake concept we all convince each other to try to live up to for a fake sense of purpose ? maybe it is a construct , but let 's be more precise about what a construct is because love is constructed from reality : our experiences , feelings , brain chemistry , cultural expectations , our lives . and this edifice can be viewed through countless dimensions : scientific , emotional , historical , spiritual , legal , or just personal . if no two people are the same , no two people 's love is the same either . so , in every loving relationship , there 's a lot to talk about and partners should be open to that , or the relationship probably wo n't last . love is always up for discussion and , sure , under construction . so , if we ca n't define it , that 's a good sign . it means we 're all still making it . wait , i did n't mean , you know what i meant .
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what is love ? seriously , though , what is it ?
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how would you explain the concept of love to a 2nd grader ?
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translator : andrea mcdonough reviewer : bedirhan cinar by now , i 'm sure you know that in just about anything you do in life , you need numbers . in particular , though , some fields do n't just need a few numbers , they need lots of them . how do you keep track of all those numbers ? well , mathematicians dating back as early as ancient china came up with a way to represent arrays of many numbers at once . nowadays we call such an array a `` matrix , '' and many of them hanging out together , `` matrices '' . matrices are everywhere . they are all around us , even now in this very room . sorry , let 's get back on track . matrices really are everywhere , though . they are used in business , economics , cryptography , physics , electronics , and computer graphics . one reason matrices are so cool is that we can pack so much information into them and then turn a huge series of different problems into one single problem . so , to use matrices , we need to learn how they work . it turns out , you can treat matrices just like regular numbers . you can add them , subtract them , even multiply them . you ca n't divide them , but that 's a rabbit hole of its own . adding matrices is pretty simple . all you have to do is add the corresponding entries in the order they come . so the first entries get added together , the second entries , the third , all the way down . of course , your matrices have to be the same size , but that 's pretty intuitive anyway . you can also multiply the whole matrix by a number , called a scalar . just multiply every entry by that number . but wait , there 's more ! you can actually multiply one matrix by another matrix . it 's not like adding them , though , where you do it entry by entry . it 's more unique and pretty cool once you get the hang of it . here 's how it works . let 's say you have two matrices . let 's make them both two by two , meaning two rows by two columns . write the first matrix to the left and the second matrix goes next to it and translated up a bit , kind of like we are making a table . the product we get when we multiply the matrices together will go right between them . we 'll also draw some gridlines to help us along . now , look at the first row of the first matrix and the first column of the second matrix . see how there 's two numbers in each ? multiply the first number in the row by the first number in the column : 1 times 2 is 2 . now do the next ones : 3 times 3 is 9 . now add them up : 2 plus 9 is 11 . let 's put that number in the top-left position so that it matches up with the rows and columns we used to get it . see how that works ? you can do the same thing to get the other entries . -4 plus 0 is -4 . 4 plus -3 is 1 . -8 plus 0 is -8 . so , here 's your answer . not all that bad , is it ? there 's one catch , though . just like with addition , your matrices have to be the right size . look at these two matrices . 2 times 8 is 16 . 3 times 4 is 12 . 3 times wait a minute , there are no more rows in the second matrix . we ran out of room . so , these matrices ca n't be multiplied . the number of columns in the first matrix has to be the same as the number of rows in the second matrix . as long as you 're careful to match up your dimensions right , though , it 's pretty easy . understanding matrix multiplication is just the beginning , by the way . there 's so much you can do with them . for example , let 's say you want to encrypt a secret message . let 's say it 's `` math rules '' . though , why anybody would want to keep this a secret is beyond me . letting numbers stand for letters , you can put the numbers in a matrix and then an encryption key in another . multiply them together and you 've got a new encoded matrix . the only way to decode the new matrix and read the message is to have the key , that second matrix . there 's even a branch of mathematics that uses matrices constantly , called linear algebra . if you ever get a chance to study linear algebra , do it , it 's pretty awesome . but just remember , once you know how to use matrices , you can do pretty much anything .
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of course , your matrices have to be the same size , but that 's pretty intuitive anyway . you can also multiply the whole matrix by a number , called a scalar . just multiply every entry by that number . but wait , there 's more !
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what 's the number called that 's used to multiply each entry in a matrix ?
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translator : tom carter reviewer : bedirhan cinar it is the spring of 1787 . the revolutionary war has been over for only six years , and the young united states is still struggling in its infancy . uprisings , boundary disputes and the lack of a common vision all plague the newborn country . in an effort to steady this precarious ship , the confederation congress calls on states to send delegates to the grand convention , to begin on may 14 in philadelphia . the delegates must draft revisions to the articles of confederation , which would then be considered by the congress and approved by the states . under the terms of the articles , all 13 states had to agree to any changes . since the purpose of the convention is just to make recommendations , not everyone is excited about attending , and frankly , some think it 's a waste of time . as men from different parts of the country began to travel down dusty , rugged roads on the way to philadelphia , not all states send delegates . in fact , rhode island never even shows up . on may 14th , only 8 delegates -- not states , but individual delegates -- are present , so they wait . finally , on may 25th , the necessary quorum of seven states is acheived . in all , 55 delegates arrive in philadelphia over the course of the convention . they are all white males , property owners , and the average age is about 44 . some are slaveholders , some had signed the declaration of independence , [ james madison , roger sherman ] and almost all are well-educated . [ benjamin franklin ] picture the delegates , james madison and george washington among them , sitting in independence hall in hot , humid philadelphia . they 're all wearing the dress of the day : frock coats , high collars and thick pants . they vote to keep their discussions secret to encourage honest debate . but that means the windows are closed , and there is no air conditioning in 1787 , not even an electric fan . and they 'll sit in that sweltering heat , in those heavy clothes , for three months . shockingly , they all keep their vow of secrecy . that could never happen today , not even for an hour-long meeting . someone would share `` james madison thinks he 's so smart . keyword : articles are dead '' via social media , and the whole thing would be a disaster . but in 1787 , there are no leaks . not even a drip that hints at what they are doing . and what they are doing is nothing short of overthrowing the very government that sent them there . within a few days , with only a seven-state quorum , and only six of those states agreeing , a handful of men change the course of history . they vote to get rid of the articles of confederation , and write a new , more nationalistic document that becomes our constitution . the risk is immense . everyone on the outside assumes they were working on recommended revisions to the articles . it 's an incredible gamble , and even when the convention presents the signed constitution on september 17th , not all delegates endorse it . the country will argue and debate for two more years before the document is adopted by the required nine out of 13 states . but instead of punishing them for their deception , today we celebrate the wisdom and vision of those men in philadelphia .
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under the terms of the articles , all 13 states had to agree to any changes . since the purpose of the convention is just to make recommendations , not everyone is excited about attending , and frankly , some think it 's a waste of time . as men from different parts of the country began to travel down dusty , rugged roads on the way to philadelphia , not all states send delegates .
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the stated purpose of the grand convention was to
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-there are 10 types of people in the world . those who understand binary , and those who do n't . matt parker : ok , it does n't really work when it 's said . but written down , the joke kind of holds . because if i do a 1 and then a 0 , that looks like the number 10 . because you expect it to be a normal base 10 number . however , if this is in binary , then this is our units column . that 's our twos column . and so this actually equals 2 in base 10 . and so you expect it to be 10 , but it 's not . it 's 2 , and that 's the joke . there are actually two types of people . those who knew this was binary , and those who did n't . -there are 10 types of people in the world . those who understand binary , those who do n't , and those who did n't expect this joke to be in base 3 . matt parker : ok , good point , because i guess you -- ok , so it depends on the base . so if you 've got 10 , but this time it 's in base 3 , then now you 've got a units column , and then a threes column , and then nines , and so on . and so that in normal numbers would be 3 in base 10 . and so the same 1 and 0 in a different base mean 3 . hence the three categories . -there are 10 types of people in the world . those who understand binary , those who do n't , and -- matt parker : look , you can generalize it to any base , ok ? 10 in base b is going to equal b in base 10 , ok ? there 's an infinite set of these jokes . cut it out . -there are 10 types of people in the world . those who understand hexadecimal , and f the rest . matt parker : ok , i give it to you , that one is actually quite funny . because now in hexadecimal , which is base 16 -- 10 in base 16 still does mean there are 16 types of people . and so there 's the one category of people who understand hexadecimal , base 16 . but then the remaining 15 in hexadecimal -- 15 is just the letter f. and so when they say f the rest , they 're saying 15 are the rest . or i guess the joke is the double meaning , where if you just say f in a sentence , it means you 're implying -- uh , fools . you 're saying they 're very foolish , all the people who do n't understand hexadecimal . -why do mathematicians confuse halloween and christmas ? because oct 31 equals dec 25 . matt parker : ok , so the joke here is that oct 31 equals dec 25 . and the surface reading is that this stands for october , and this stands for december . but it does n't . oct can stand for the eighth thing , because october is the eighth month in the -- it was until julius caesar messed with it . and dec used to be the 10th month , blah , blah , blah . so anyway , instead of using these as months , you can use oct to mean base 8 . so instead of 31 being in our normal base 10 setup , if we put it into base 8 , you have a units column . you have an eights column . and so you 've now got one unit and three 8 's . and three 8 's is 24 , plus a single unit equals 25 . and so 31 in base 8 equals 25 in base 10 , which is why one equals the other , and why a mathematician would confuse them . brady haran : this video was supported by audible.com . and if you 'd like to download one of their 100,000 titles for free , go to audible.com/numberphile . i actually sampled the product myself in the last few weeks . i downloaded a couple of mountaineering books while i was holidaying in nepal . i love books about mountains . these are the two i chose . they were both excellent . and it was actually really good fun to be walking through the mountains while listening to the book , having it sort of inside my head . so i recommend those two as possible ones when you download your free one . that 's audible.com/numberphile , and thanks to them for supporting our videos . [ laughter ]
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-there are 10 types of people in the world . those who understand binary , those who do n't , and those who did n't expect this joke to be in base 3 . matt parker : ok , good point , because i guess you -- ok , so it depends on the base .
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why does the binary joke ( the first joke ) work for binary through base 9 ?
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how fast are you moving right now ? that seems like an easy question . the first tempting answer is , `` i 'm not moving . '' upon further reflection , you realize that maybe the earth 's motion counts . so , a second tempting answer is , `` 19 miles/second around the sun . '' but then you recall learning that the sun moves around the center of the milky way galaxy , and the milky way moves within the local group of galaxies , and the local group moves within the virgo cluster , and the virgo cluster moves within ... `` how fast are you moving ? '' is not an easy question . when mission control tells astronauts how fast they 're going , there 's always an assumed standard of rest . at the start of the voyage , speeds are given relative to the launchpad . but later , when the launchpad is just one more arbritrary place down there on earth 's spinning surface , speeds are given relative to the idealized , non-spinning pinpoint center of earth . on their way to the moon , apollo astronauts had a hard time answering the question , `` how fast are you moving ? '' speed away from earth was one thing , and speed toward the moon was quite another . that 's because the earth and the moon move relative to one another . ah , of course ! speed is a relative quantity . when captain kirk ask lieutenant sulu if the starship enterprise has reached a speed of warp 7 , sulu should reply , `` relative to what , captain ? '' such a sassy reply may get subordinate starfleet officers in trouble , but it is the only good answer to the question , `` how fast are you moving ? '' this is basic relatively talking . not fancy einsteinian relativity , but good old fashioned ( and still correct ) galilean relativity . galileo seems to have been the first person to realize that there is no such thing as an absolute speed . speeds are relative . this means that speeds only have meaning when they are referred to a reference frame . presumably that reference frame is itself at rest . but then we have to ask again , `` at rest relative to what ? '' because even the concept of rest has lost any hint of absolute meaning . speed is relative , and rest is relative . earth 's speed is 19 miles/second relative to the sun . the enterprise 's speed is warp 7 relative to the center of the milky way galaxy . your speed is zero relative to your easy chair . but depending on where you sit , it is hundreds of miles/hour relative to earth 's center . when we furrow a brow and ask , `` but how fast is earth really moving ? '' we imagine spaceship earth plowing through the ocean of space as it orbits the sun . but space is not an ocean . it has no substance as water does . space is not a thing ; space is nothing . space is no thing . you can move between two points in space , say between earth and mars , but you ca n't move through space . there 's nothing to move through . it 's like trying to say how much a hole weighs . a hole weighs exactly nothing because a hole is nothing . it 's a void , and so is space . to move relative to nothing is meaningless . the concepts of speed and of rest have only relative meaning . they are absolutely meaningless . they mean something only with respect to arbitrarily chosen , artificial frames of reference . if , someday , you are buckled into your spaceship , and you see from the side window , say , a space station whizz by at constant speed , there is no way to know which of you is really moving . neither of you is really moving because there is no deep reality about constant speed . constant speed in a straight line has only relative meaning , a kind of relative reality . does this mean that all motion is relative ? no ! some motions have only relative meaning , but some motions have absolute meaning , are absolutely real . for example , constant speed is relative , but change in speed is absolute . calling something absolute in science means that arbitrary standards are not used in its measurement . it is unambiguously measurable . when your spaceship fires its engines , your change in speed is beyond doubt . you feel it in your stomach , and your ship 's sensors can measure it . outside your window , the passing space station may seem to be changing speed , but the beings inside the station will not feel it . and no sensors can measure it . you are really changing speed , and they are really are not . there 's something absolutely real about changes in speed . the same goes for rotation . if your spaceship is spinning , you can feel it , and your ship 's sensors can measure it . the space station outside may seem to be going around you , but it is you who feels queasy , not the folks in the space station . you are really spinning , and they really are not . there 's something absolutely real about rotation . so , some motions are relative , and some are not . there is no deep reality about constant speed , but changes in speed are deeply real , and so are rotations . we have to be thoughtful in our analysis of everyday experience in order to identify what is deeply real . since we can be fooled by perceptions as basic as speed , maybe every perception deserves careful scrutiny . this is what inspired einstein to his incredible insights about the speed of light and forward time travel . knowing how to identify what is deeply real is tough and important work . if a police officer ever pulls you over for speeding and asks , & amp ; amp ; quot ; do you know how fast you were going ? & amp ; amp ; quot ; an insightful , though perhaps unwise , reply would be , `` relative to what ? '' and then , as you sit in the backseat of the police car and feel it accelerate toward jail , you can add , & amp ; amp ; quot ; but some things are absolute ! & amp ; amp ; quot ;
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it has no substance as water does . space is not a thing ; space is nothing . space is no thing .
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empty space is nothing— “ no thing ” —in the same way as what else ?
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translator : andrea mcdonough reviewer : jessica ruby mysteries of vernacular : sarcophagus , a stone coffin typically adorned with decorative carvings or inscriptions . the history of the word sarcophagus is so skin-crawlingly grotesque , it seems to come right out of a low-budget horror film . rather than having a b-movie origin , however , its roots can be traced back to the early roman empire where the greek word sarkophagus was used to describe the limestone that a coffin was made of , not the coffin itself . according to the roman scholar pliny the elder , citizens of the empire believed that limestone from a quarry near troy would dissolve flesh . for this reason , it was quite desireable in the construction of coffins . though it 's unclear if the belief was widespread or even accurately reported by pliny , what is certain is that sarkophagus came from the greek words sark , meaning flesh , and phagein , a verb meaning to eat . from flesh-eating stone to stone coffin , it 's a fitting etymology for the final resting place of the deceased .
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rather than having a b-movie origin , however , its roots can be traced back to the early roman empire where the greek word sarkophagus was used to describe the limestone that a coffin was made of , not the coffin itself . according to the roman scholar pliny the elder , citizens of the empire believed that limestone from a quarry near troy would dissolve flesh . for this reason , it was quite desireable in the construction of coffins .
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ancient roman sarcophagi were often decorated with ornate reliefs . what kinds of scenes do you think you would find on a sarcophagus from this time period ?
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i am in the coffee room where element 109 , meitnerium was named . in here , imagine it : 20 people sitting round arguing “ what are we going to call this new element ? ” writing the names on the blackboard…they rubbed it off ! but there , they had the whole choice of what the elements were called . like many others of these very heavy elements , meitnerium was made by taking a nucleus of a heavy element and banging into it a lighter element . in the case of this one you have lead with atomic number 82 and bang into it cobalt , or alternatively you can have bismuth which has atomic number 83 and bang in iron which has atomic number one less than cobalt so you have 2 different ways of making the same element . i was just told by sigurd hofmann , one of the discoverers , they chose the name , mietnerium because lisa mietner who was the co-discoverer of fission of atoms never got the nobel prize , her collaborator otto hahn got the nobel prize she didn ’ t . now she has got an element named after her , and he hasn ’ t , so her name will live longer than his . i think it would be really exciting to choose the name of an element . well professor , you are sitting next to a man who does get to name elements , this is your one chance to tell him what you think he should call any future elements that he might get to have a say in , let ’ s see what you are going to suggest to him . i think , i still think that it would be nice to honour max planck and i also think that planckium is a nice name it rolls off the tongue . what do you think ? planckium , will you bear that one in mind for us next time you have to name an element ? i think now , planckium , we can write in bold letters because he already was on our list . ok there you go ! planckium might be in the running next time , are you happy ? yes , thankyou . ok. lisa mietner was the first woman ever to get a phd , a doctorate in physics , in austria and then she moved to berlin . during the first world war she worked on a mobile x-ray unit for x-raying wounded soldiers and then she worked in berlin with max planck . and there is a very nice story that rutherford sent radioactive samples to them by post from cambridge and she could tell when a parcel was coming to her from cambridge before looking at it , while the postman was still holding it , because her geiger-counter started detecting radioactivity coming out of the parcel . people were not quite so careful when they sent radioactive samples in those days as they are now .
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i am in the coffee room where element 109 , meitnerium was named . in here , imagine it : 20 people sitting round arguing “ what are we going to call this new element ? ” writing the names on the blackboard…they rubbed it off !
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where was the proposed name for element 109 decided after a discussion between 20 scientists ?
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hi i ’ m john green , this is crash course us history , and today we 're going to tell the story of how a group of plucky english people struck a blow for religious freedom , and founded the greatest , freest and fattest nation the world has ever seen . [ libertage ] these brits entered a barren land containing no people , and quickly invented the automobile , baseball and star trek and we all lived happily ever after . mr. green , mr. green , if it is really that simple , i am so getting an a in this class . oh , me from the past , you 're just a delight . [ theme music ] so most americans grew up hearing that the united states was founded by pasty english people who came here to escape religious persecution . and that 's true of the small proportion of people who settled in the massachusetts bay and created what we now know is new england . but these pilgrims and puritans , there 's a difference , weren ’ t the first people or even the first europeans to come to the only part of the globe we did n't paint over . in fact they weren ’ t the first english people . the first english people came to virginia . off topic but how weird is it that the first permanent english colony in the americas was named not for queen elizabeth ’ s epicness but for her supposed chastity . right anyway , those first english settlers were n't looking for religious freedom , they wanted to get rich . so the first successful english colony in america was founded in jamestown , virginia in 1607 . i say `` successful '' because there were two previous attempts to colonize the region . they were both epic failures . the more famous of which was the colony of roanoke island set up by sir walter raleigh , which is famous because all the colonists disappeared leaving only the word `` croatoan '' on carved into a tree . jamestown was a project of the virginia company , which existed to make money for its investors , something it never did . the hope was that they would find gold in the chesapeake region like the spanish had in south america , so there were a disproportionate number of goldsmiths and jewelers there to fancy up that gold which of course did not exist . anyway , it turns out that jewelers dislike farming -- so much so , that captain john smith who soon took over control of the island once said that they would rather starve than farm . so in the first year , half of the colonists died . 400 replacements came , but , by 1610 , after a gruesome winter called `` the starving time , '' the number of colonists had dwindled to 65 . and eventually word got out that the new world ’ s 1 year survival rate was like 20 % and it became harder to find new colonists . but 1618 , a virginia company hit upon a recruiting strategy called the headright system which offered 50 acres of land for each person that a settler paid to bring over . and this enabled the creation of a number of large estates , which were mostly worked on and populated by indentured servants . indentured servants were n't quite slaves , but they were kind of temporary slaves . like they could be bought and sold and they had to do what their masters commanded . but after seven to ten years of that , if they were n't dead , they were paid their freedom dues which they hoped would allow them to buy farms of their own . sometimes that worked out , but often either the money was n't enough to buy a farm , or else they were too dead to collect it . even more ominously in 1619 , just 12 years after the founding of jamestown , the first shipment of african slaves arrived in virginia . so the colony probably would have continued to struggle along , if they had n't found something that people really loved : tobacco . tobacco had been grown in mexico since at least 1000 bce , but the europeans had never seen it and it proved to be kind of a `` thank you for the small pox ; here 's some lung cancer ” gift from the natives . interestingly king james hated smoking . he called it “ a custom loathsome to the eye and hateful to the nose '' but he loved him some tax revenue , and nothing sells like drugs . by 1624 virginia was producing more than 200,000 pounds of tobacco per year . by the 1680s , more than 30 million pounds per year . tobacco was so profitable the colonists created huge plantations with very little in the way of towns or infrastructure to hold the social order together , a strategy that always works out brilliantly . the industry also structured virginian society . first off , most of the people who came in the 17th century , three-quarters of them , were servants . so virginia became a microcosm of england : a small class of wealthy landowners sitting atop a mass of servants . that sounds kind of dirty but it was mostly just sad . the society was also overwhelmingly male , because male servants were more useful in the tobacco fields , they were the greatest proportion of immigrants . in fact they outnumbered women 5 to 1 . the women who did come over were mostly indentured servants , and if they were to marry , which they often did because they were in great demand , they had to wait until their term of service was up . this meant delayed marriage which meant fewer children which further reduced the number of females . life was pretty tough for these women , but on the upside virginia was kind of a swamp of pestilence , so their husbands often died , and that created a small class of widows or even unmarried women who , because of their special status , could make contracts and own property , so that was good , sort of . ok. a quick word about maryland . maryland was the second chesapeake colony , founded in 1632 , and by now there was no messing around with joint stock companies . maryland was a proprietorship : a massive land grant to a single individual named cecilius calvert . calvert wanted to turn maryland into like a medieval feudal kingdom to benefit himself and his family , and he was no fan of the representational institutions that were developing in virginia . also calvert was catholic , and catholics were welcome in maryland which was n't always the case elsewhere . speaking of which , let 's talk about massachusetts . so jamestown might have been the first english colony , but massachusetts bay is probably better known . this is largely because the colonists who came there were so recognizable for their beliefs and also for their hats . that ’ s right . i ’ m talking about the pilgrims and the puritans . and no , i will not be talking about thanksgiving ... is a lie . i can ’ t help myself . but only to clear up the difference between pilgrims and puritans and also to talk about squanto . god i love me some squanto . let 's go to the thought bubble . most of the english men and women who settled in new england were uber-protestant puritans who believed the protestant church of england was still too catholic-y with its kneeling and incense and extravagantly-hatted archbishops . the particular puritans who , by the way did not call themselves that -- other people did , who settled in new england were called congregationalists because they thought congregations should determine leadership and worship structures , not bishops . the pilgrims were even more extreme . they wanted to separate more or less completely from the church of england . so first they fled to the netherlands , but the dutch were apparently too corrupt for them , so they rounded up investors and financed a new colony in 1620 . they were supposed to land in virginia , but in what perhaps should have been taken as an omen , they were blown wildly off course and ended up in what 's now massachusetts , founding a colony called plymouth . while still on board their ship the mayflower , 41 of the 150 or so colonists wrote and signed an agreement called the mayflower compact , in which they all bound themselves to follow `` just and equal laws '' that their chosen representatives would write-up . since this was the first written framework for government in the us , it 's kind of a big deal . but anyway , the pilgrims had the excellent fortune of landing in massachusetts with 6 weeks before winter , and they had the good sense not to bring very much food with them or any farm animals . half of them died before winter was out . the only reason they did n't all die was that local indians led by squanto gave them food and saved them . a year later , grateful that they had survived mainly due to the help of an alliance with the local chief massasoit , and because the indians had taught them how to plant corn and where to catch fish , the pilgrims held a big feast : the first thanksgiving . thanks thought bubble ! and by the way , that feast was on the fourth thursday in november , not mid-october as is celebrated in some of these green areas we call not america . anyway squanto was a pretty amazing character and not only because he helped save the pilgrims . he found that almost all of his tribe , the patuxet had been wiped out by disease and eventually settled with the pilgrims on the site of his former village and then died ... of disease because it is always ruining everything . so the pilgrims struggled on until 1691 when their colony was subsumed by the larger and much more successful massachusetts bay colony . the massachusetts bay colony was chartered in 1629 by london merchants who , like the founders of the virginia company , hoped to make money . but unlike virginia , the board of directors relocated from england to america , which meant that in massachusetts they had a greater degree of autonomy and self-government than they did in virginia . social unity was also much more important in massachusetts than it was in virginia . the puritans ' religious mission meant that the common good was , at least at first , put above the needs or the rights of the individual . those different ideas in the north and south about the role of government would continue ... until now . oh god . it 's time for the mystery document ? the rules are simple . i read the mystery document which i have not seen before . if i get it right , then i do not get shocked with the shock pen , and if i get it wrong i do . all right . `` we must be knit together in this work as one man , we must entertain each other in brotherly affection , we must be willing to abridge ourselves of our superfluities ( su-per-fluities ? i do n't know ) , for the supply of others necessities , we must uphold a familiar commerce together in all meekness , gentleness , patience and liberality , ... for we must consider that we shall be as a city upon a hill , the eyes of all people are upon us ; so that if we shall deal falsely with our god in this work we have undertaken and so cause him to withdraw his present help from us , we shall be made a story and a byword through the world . '' alright , first thing i noticed : the author of this document is a terrible speller or possibly wrote this before english was standardized . also , a pretty religious individual . and the community in question seems to embrace something near socialism : abridging the superfluous for others ' necessities . also it says that the community should be like a city upon a hill , like a model for everybody . and because of that metaphor , i know exactly where it comes from : the sermon `` a model of christian charity '' by john winthrop . yes ! yes ! no punishment ! this is one of the most important sermons in american history . it shows us just how religious the puritans were , but it also shows us that their religious mission was n't really one of individualism but of collective effort . in other words , the needs of the many outweigh the needs of the few or the one . but this city on a hill metaphor is the basis for one kind of american exceptionalism : the idea that we are so special and so godly that we will be a model to other nations , at least as long , according to winthrop , as we act together . lest you think winthrop ’ s words were forgotten , they did become the centerpiece of ronald reagan ’ s 1989 farewell address . okay so new england towns were governed democratically , but that does n't mean that the puritans were big on equality or that everybody was able to participate in government because no . the only people who could vote or hold office were church members , and to be a full church member you had to be a “ visible saint '' , so really , power stayed in the hands of the church elite . the same went for equality . while it was better than in the chesapeake colonies or england , as equality went ... eh , pretty unequal . as john winthrop declared , `` some must be rich , and some poor . some high , an eminent in power , and dignity ; others mean and in subjection . '' or as historian eric foner put it `` inequality was considered an expression of god 's will and while some liberties applied to all inhabitants , there were separate lists of rights for freemen , women , children and servants . '' there was also slavery in massachusetts . the first slaves were recorded in the colony in 1640 . however , puritans really did foster equality in one sense . they wanted everyone to be able to read the bible . in fact , parents could be punished by the town councils for not properly instructing their children in making them literate . but when roger williams called for citizens to be able to practice any religion they chose , he was banished from the colonies . so was ann hutchinson who argued the church membership should be based on inner grace and not on outward manifestations like church attendance . williams went on to found rhode island , so that worked out fine for him , but hutchinson , who was doubly threatening to massachusetts because she was a woman preaching unorthodox ideas , was too radical and was further banished to westchester , new york where she and her family were killed by indians . finally , somebody who does n't die of disease or starvation . so americans like to think of their country as being founded by pioneers of religious freedom who were seeking liberty from the oppressive english . we 've already seen that 's only partly true . for one thing , puritan ideas of equality and representation were n't particularly equitable or representational . in truth , america was also founded by indigenous people and by spanish settlers , and the earliest english colonies were n't about religion ; they were about money . we 'll see this tension between american mythology and american history again next week and also every week . thanks for watching ; i ’ ll see you next time . crash course is produced and directed by stan muller , our script supervisor is meredith danko , the associate producer is danica johnson , the show is written by my high school history teacher , raoul meyer and myself , and our graphics team is thought bubble . if you have questions about today 's video or really about anything about american history , ask them in comments ; the entire crash course team and many history professionals are there to help you . thanks for watching crash course . please make sure you are subscribed and , as we say in my home town , `` do n't forget to be awesome . ''
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oh , me from the past , you 're just a delight . [ theme music ] so most americans grew up hearing that the united states was founded by pasty english people who came here to escape religious persecution . and that 's true of the small proportion of people who settled in the massachusetts bay and created what we now know is new england .
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the united states of america was originally founded by white men and their families who traveled to a new land to escape religious persecution .
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in the early days of organic chemistry , chemists understood that molecules were made of atoms connected through chemical bonds . however , the three-dimensional shapes of molecules were utterly unclear , since they could n't be observed directly . molecules were represented using simple connectivity graphs like the one you see here . it was clear to savvy chemists of the mid-19th century that these flat representations could n't explain many of their observations . but chemical theory had n't provided a satisfactory explanation for the three-dimensional structures of molecules . in 1874 , the chemist va n't hoff published a remarkable hypothesis : the four bonds of a saturated carbon atom point to the corners of a tetrahedron . it would take over 25 years for the quantum revolution to theoretically validate his hypothesis . but va n't hoff supported his theory using optical rotation . va n't hoff noticed that only compounds containing a central carbon bound to four different atoms or groups rotated plane-polarized light . clearly there 's something unique about this class of compounds . take a look at the two molecules you see here . each one is characterized by a central , tetrahedral carbon atom bound to four different atoms : bromine , chlorine , fluorine , and hydrogen . we might be tempted to conclude that the two molecules are the same , if we just concern ourselves with what they 're made of . however , let 's see if we can overlay the two molecules perfectly to really prove that they 're the same . we have free license to rotate and translate both of the molecules as we wish . remarkably though , no matter how we move the molecules , we find that perfect superposition is impossible to achieve . now take a look at your hands . notice that your two hands have all the same parts : a thumb , fingers , a palm , etc . like our two molecules under study , both of your hands are made of the same stuff . furthermore , the distances between stuff in both of your hands are the same . the index finger is next to the middle finger , which is next to the ring finger , etc . the same is true of our hypothetical molecules . all of their internal distances are the same . despite the similarities between them , your hands , and our molecules , are certainly not the same . try superimposing your hands on one another . just like our molecules from before , you 'll find that it ca n't be done perfectly . now , point your palms toward one another . wiggle both of your index fingers . notice that your left hand looks as if it 's looking in a mirror at your right . in other words , your hands are mirror images . the same can be said of our molecules . we can turn them so that one looks at the other as in a mirror . your hands - and our molecules - possess a spatial property in common called chirality , or handedness . chirality means exactly what we 've just described : a chiral object is not the same as its mirror image . chiral objects are very special in both chemistry and everyday life . screws , for example , are also chiral . that 's why we need the terms right-handed and left-handed screws . and believe it or not , certain types of light can behave like chiral screws . packed into every linear , plane-polarized beam of light are right-handed and left-handed parts that rotate together to produce plane polarization . chiral molecules , placed in a beam of such light , interact differently with the two chiral components . as a result , one component of the light gets temporarily slowed down relative to the other . the effect on the light beam is a rotation of its plane from the original one , otherwise known as optical rotation . va n't hoff and later chemists realized that the chiral nature of tetrahedral carbons can explain this fascinating phenomenon . chirality is responsible for all kinds of other fascinating effects in chemistry , and everyday life . humans tend to love symmetry and so if you look around you , you 'll find that chiral objects made by humans are rare . but chiral molecules are absolutely everywhere . phenomena as separate as optical rotation , screwing together furniture , and clapping your hands all involve this intriguing spatial property .
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we can turn them so that one looks at the other as in a mirror . your hands - and our molecules - possess a spatial property in common called chirality , or handedness . chirality means exactly what we 've just described : a chiral object is not the same as its mirror image .
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chirality is a property that concerns the relationship between a molecule and its :
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imagine if half the people in your neighborhood , your city , or even your whole country were wiped out . it might sound like something out of an apocalyptic horror film , but it actually happened in the 14th century during a disease outbreak known as the black death . spreading from china through asia , the middle east , africa and europe , the devastating epidemic destroyed as much as 1/5 of the world 's population , killing nearly 50 % of europeans in just four years . one of the most fascinating and puzzling things abut the black death is that the illness itself was not a new phenomenon but one that has affected humans for centuries . dna analysis of bone and tooth samples from this period , as well as an earlier epidemic known as the plague of justinian in 541 ce , has revealed that both were caused by yersinia pestis , the same bacterium that causes bubonic plague today . what this means is that the same disease caused by the same pathogen can behave and spread very differently throughout history . even before the use of antibiotics , the deadliest oubreaks in modern times , such as the ones that occurred in early 20th century india , killed no more than 3 % of the population . modern instances of plague also tend to remain localized , or travel slowly , as they are spread by rodent fleas . but the medieval black death , which spread like wildfire , was most likely communicated directly from one person to another . and because genetic comparisons of ancient to modern strains of yersinia pestis have not revealed any significantly functional genetic differences , the key to why the earlier outbreak was so much deadlier must lie not in the parasite but the host . for about 300 years during the high middle ages , a warmer climate and agricultural improvements had led to explosive population growth throughout europe . but with so many new mouths to feed , the end of this warm period spelled disaster . high fertility rates combined with reduced harvest , meant the land could no longer support its population , while the abundant supply of labor kept wages low . as a result , most europeans in the early 14th century experienced a steady decline in living standards , marked by famine , poverty and poor health , leaving them vulnerable to infection . and indeed , the skeletal remains of black death victims found in london show telltale signs of malnutrition and prior illness . the destruction caused by the black death changed humanity in two important ways . on a societal level , the rapid loss of population led to important changes in europe 's economic conditions . with more food to go around , as well as more land and better pay for the surviving farmers and workers , people began to eat better and live longer as studies of london cemeteries have shown . higher living standards also brought an increase in social mobility , weakening feudalism , and eventually leading to political reforms . but the plague also had an important biological impact . the sudden death of so many of the most frail and vulnerable people left behind a population with a significantly different gene pool , including genes that may have helped survivors resist the disease . and because such mutations often confer immunities to multiple pathogens that work in similar ways , research to discover the genetic consequences of the black death has the potential to be hugely beneficial . today , the threat of an epidemic on the scale of the black death has been largely eliminated thanks to antibiotics . but the bubonic plague continues to kill a few thousand people worldwide every year , and the recent emergence of a drug-resistant strain threatens the return of darker times . learning more about the causes and effects of the black death is important , not just for understanding how our world has been shaped by the past . it may also help save us from a similar nightmare in the future .
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as a result , most europeans in the early 14th century experienced a steady decline in living standards , marked by famine , poverty and poor health , leaving them vulnerable to infection . and indeed , the skeletal remains of black death victims found in london show telltale signs of malnutrition and prior illness . the destruction caused by the black death changed humanity in two important ways . on a societal level , the rapid loss of population led to important changes in europe 's economic conditions .
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what has dna analysis revealed about the black death ?
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imagine you 're walking through a forest . everything might seem quiet ... but beneath your feet is a flurry of conversation . all the plants around you are actually talking to each other . the trees and the shrubs and the flowers are passing information back and forth , with serious life and death consequences . so , how are they communicating ? they ’ re using a giant network of fungi—one so pervasive and powerful that some scientists have started comparing it to the internet . they ’ re calling it the “ wood wide web. ” i ’ m anna , and this is gross science . the so-called wood wide web is made up of what are called “ mycorrhizal fungi. ” there are many different types of mycorrhizal fungi , but generally these little guys will grow on the roots of plants and provide them with water and nutrients—like nitrogen and phosphorus—in exchange for sugars from the plant . while they ’ re incredibly thin , the threads of the fungi can be up to 1000 times the length of a tree root . this allows the fungi to connect together many different plants . once connections are made , the fungi can act almost like the neurons in our brain , transporting signals from plant to plant . and these networks are everywhere . it ’ s estimated that around 90 % of land plants are connected to some kind of mycorrhizal network . so , how can plants use these networks ? well , to begin with , they can help each other out in times of stress . for example , during the fall months , when paper birch trees lose their leaves and can ’ t produce sugar , douglas-fir trees may shuttle them nutrients through the fungal network . and in the summer , when paper birch trees have lots of leaves , they send sugars to young douglas-fir saplings growing in their shadows . plants can also warn each other of danger . douglas-fir trees connected by a fungal network can alert their ponderosa pine neighbors if they ’ re attacked by budworms . in response , the neighboring ponderosa pine trees will produce insect-repelling chemicals—even though they haven ’ t been directly exposed to the insects themselves . mycorrhizal fungi can also enable parental care of among plants . some adult trees will help out their younger relatives by sending those seedlings more nutrients through the fungal network than they send to strangers . the adults may even make more room for them in the soil by reducing the number of their own roots . but not everyone is so generous . much like our internet , things can sometimes get a little nasty on the wood wide web . take black walnut trees , for example . they can spread poison through the network , hindering the growth of their neighbors . and the fungi making up the network can be just as tricky . mycorrhizal fungi tend to pick favorites . they may share resources with one species of tree , but bleed another species dry without giving anything back in return . the fungi may also judge a plant 's health . if they think it ’ s too weak or sick , they may not allow it to receive nutrients or danger signals from the network . now , we ’ re only beginning to understand how complex these relationships get . but imagine the possibilities for agriculture and forestry . if we find out certain species share well across the network , maybe we can plant them near each other to yield better harvests , or grow healthier forests . so next time you ’ re walking through the woods or the park don ’ t forget to thank the fungal web beneath your feet . ew .
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now , we ’ re only beginning to understand how complex these relationships get . but imagine the possibilities for agriculture and forestry . if we find out certain species share well across the network , maybe we can plant them near each other to yield better harvests , or grow healthier forests .
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how could we potentially use an understanding of the mycorrhizal network to assist in agriculture or forestry ?
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what if electricity could travel forever without being diminished ? what if a computer could run exponentially faster with perfect accuracy ? what technology could those abilities build ? we may be able to find out thanks to the work of the three scientists who won the nobel prize in physics in 2016 . david thouless , duncan haldane , and michael kosterlitz won the award for discovering that even microscopic matter at the smallest scale can exhibit macroscopic properties and phases that are topological . but what does that mean ? first of all , topology is a branch of mathematics that focuses on fundamental properties of objects . topological properties do n't change when an object is gradually stretched or bent . the object has to be torn or attached in new places . a donut and a coffee cup look the same to a topologist because they both have one hole . you could reshape a donut into a coffee cup and it would still have just one . that topological property is stable . on the other hand , a pretzel has three holes . there are no smooth incremental changes that will turn a donut into a pretzel . you 'd have to tear two new holes . for a long time , it was n't clear whether topology was useful for describing the behaviors of subatomic particles . that 's because particles , like electrons and photons , are subject to the strange laws of quantum physics , which involve a great deal of uncertainty that we do n't see at the scale of coffee cups . but the nobel laureates discovered that topological properties do exist at the quantum level . and that discovery may revolutionize materials science , electronic engineering , and computer science . that 's because these properties lend surprising stability and remarkable characteristics to some exotic phases of matter in the delicate quantum world . one example is called a topological insulator . imagine a film of electrons . if a strong enough magnetic field passes through them , each electron will start traveling in a circle , which is called a closed orbit . because the electrons are stuck in these loops , they 're not conducting electricity . but at the edge of the material , the orbits become open , connected , and they all point in the same direction . so electrons can jump from one orbit to the next and travel all the way around the edge . this means that the material conducts electricity around the edge but not in the middle . here 's where topology comes in . this conductivity is n't affected by small changes in the material , like impurities or imperfections . that 's just like how the hole in the coffee cup is n't changed by stretching it out . the edge of such a topological insulator has perfect electron transport : no electrons travel backward , no energy is lost as heat , and the number of conducting pathways can even be controlled . the electronics of the future could be built to use this perfectly efficient electron highway . the topological properties of subatomic particles could also transform quantum computing . quantum computers take advantage of the fact that subatomic particles can be in different states at the same time to store information in something called qubits . these qubits can solve problems exponentially faster than classical digital computers . the problem is that this data is so delicate that interaction with the environment can destroy it . but in some exotic topological phases , the subatomic particles can become protected . in other words , the qubits formed by them ca n't be changed by small or local disturbances . these topological qubits would be more stable , leading to more accurate computation and a better quantum computer . topology was originally studied as a branch of purely abstract mathematics . thanks to the pioneering work of thouless , haldane , and kosterlitz , we now know it can be used to understand the riddles of nature and to revolutionize the future of technologies .
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first of all , topology is a branch of mathematics that focuses on fundamental properties of objects . topological properties do n't change when an object is gradually stretched or bent . the object has to be torn or attached in new places .
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topological properties don ’ t change when an object is :
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have you ever heard the sound of frogs calling at night ? for hundreds of millions of years , this croaking lullaby has filled the nighttime air . but recent studies suggest that these frogs are in danger of playing their final note . over the past few decades , amphibian populations have been rapidly disappearing worldwide . nearly one-third of the world 's amphibian species are endanger of extinction , and over 100 species have already disappeared . but do n't worry , there 's still hope . before we get into how to save the frogs , let 's start by taking a look at why they 're disappearing and why it 's important to keep them around . habitat destruction is the number one problem for frog populations around the world . there are seven billion humans on the planet , and we compete with frogs for habitat . we build cities , suburbs , and farms on top of frog habitat and chop forests and drain the wetlands that serve as home for numerous amphibian populations . climate change alters precipitation levels , drying up ponds , streams , and cloud forests . as the earth 's human population continues to grow , so will the threats amphibians face . there are a variety of other factors contributing to the frogs ' decline . over-harvesting for the pet and food trade results in millions of frogs being taken out of the wild each year . invasive species , such as non-native trout and crawfish , eat native frogs . humans are facilitating the spread of infectious diseases by shipping over 100 million amphibians around the world each year for use as food , pets , bait , and in laboratories and zoos , with few regulations or quarantines . one of these diseases , chytridiomycosis , has driven stream-dwelling amphibian populations to extinction in africa , australia , europe , and north , central , and south america . on top of all these problems , we add hundreds of millions of kilograms of pesticides to our ecosystems each year . and these chemicals are easily absorbed through amphibians ' permeable skin , causing immunosuppression , or a weakened immune system , and developmental deformities . okay , so why are these little green guys worth keeping around ? frogs are important for a multitude of reasons . they 're an integral part of the food web , eating flies , ticks , mosquitoes , and other disease vectors , thus , protecting us against malaria , dengue fever , and other illnesses . tadpoles keep waterways clean by feeding on algae , reducing the demand on our community 's filtration systems and keeping our cost of water low . frogs serve as a source of food for birds , fish , snakes , dragonflies , and even monkeys . when frogs disappear , the food web is disturbed , and other animals can disappear as well . amphibians are also extremely important in human medicine . over ten percent of the nobel prizes in physiology and medicine have gone to researchers whose work depended on amphibians . some of the antimicrobial peptides on frog skin can kill hiv , some act as pain killers , and others serve as natural mosquito repellents . many discoveries await us if we can save the frogs , but when a frog species disappears , so does any promise it holds for improving human health . fortunately , there are lots of ways you can help , and the best place to start is by improving your ecological footprint and day-to-day actions . the next time you listen to that nighttime lullaby , do n't think of it as just another background noise , hear it as a call for help , sung in perfect croaking harmony .
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okay , so why are these little green guys worth keeping around ? frogs are important for a multitude of reasons . they 're an integral part of the food web , eating flies , ticks , mosquitoes , and other disease vectors , thus , protecting us against malaria , dengue fever , and other illnesses .
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pesticides can harm frogs by _____ .
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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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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 .
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the four differing nucleotide parts , called bases , are made of a few :
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[ go project films ] [ when a town runs dry ] [ ♪ music ♪ ] my grandfather started the farm . and we 've been farming here ever since . for the last couple years , we have n't had the crop production that we 're used to when we have adequate water . we 're struggling . i 've had to sell some property to try to keep in business . the little bit of land that we did sell was a very emotional thing to do because that 's land that i worked with my dad and it 's gone . growing up in stratford was a wonderful thing as a child . [ children talking ] the canals were always filled with water . we could spend a whole day at the canal trying to catch crawdads , hunting for frogs , fishing . we 'd ride our bikes off into the river . and we would swim in it . nowadays , there 's no water there . i grew up in yemen . living over there was really hard . so that is why we came to the united states . first we moved to oakland but i did n't feel like home there . i wanted to move to a smaller city . that 's when i found stratford . i really like living here but sometimes it gets hard with the work . since the drought has started we lost half the business . most of the people that come to my store they work for the farmers . most of the farmers they get broke , the workers they go somewhere else to find work . i really feel bad about the people . they have a rough time . this makes me sad because we were welcomed by all the people here . being able to work with the ground and with nature has been very satisfying . but of late when the water has become scarce we do n't get a lot of help from the people who want the food that we grow . this year probably two-thirds to half of our farm has not been put into cultivation because of lack of water . without food production , there 's no jobs out in the rural communities . when you have the commodity we tend to not plan for the future . otherwise we should have been planning years ago . you do n't start thinking about reality until you start seeing the writing on the wall . water is one thing , but you take a step back and you look at what 's going on in the community , and it 's heartbreaking . you 've got to be grateful for the people that are there from dusk to dawn or even later than that . when those stores close their doors , we 're really going to be hurting in that little community . you know , where are our kids going to be able to go to go get a snack ? when people do n't have the money i start to run a tab with them . some people they pay me back , some people they ca n't because no work . okay kenny , thank you . - you have a good day . - we 'll see you next time . when you know the people when they ca n't make no money , no work , it 's hard to say `` you know '' pay me my money back and you know they do n't have it . we lost a lot . sometimes you think i do n't know what to do anymore and we just keep going . anything helps , you know , anything helps . any time someone puts a little bit more effort into the community , [ whistle ] the community stands stronger . and you just hope that it grasps and it keeps moving forward . i would like my kids to take over the farm and keep it going but if it continues to deteriorate then the future is not bright in agriculture . [ cheering ] the only thing we can do is sell more land and that 's like selling part of yourself . [ screams ] there 's no better life . it 's not fast . there 's not a lot of money in it , but it 's a fair living . so it would really be sad for me to see this lifestyle come to an end . i hope the water is coming back . when the rain comes back i hope a lot of work and a lot of people come back . i really like living in this town . i do n't want to leave this town . [ credits ] [ ©2016 go project films ]
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when the rain comes back i hope a lot of work and a lot of people come back . i really like living in this town . i do n't want to leave this town .
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what is the name of the town highlighted in the film ?
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translator : andrea mcdonough reviewer : bedirhan cinar what do harry potter , katniss everdeen , and frodo all have in common with the heroes of ancient myths ? ( roar ) what if i told you they are all variants of the same hero ? do you believe that ? joseph campbell did . he studied myths from all over the world and published a book called `` the hero with a thousand faces , '' retelling dozens of stories and explaining how each represents the mono-myth , or hero 's journey . so , what is the `` hero 's journey '' ? think of it as a cycle . the journey begins and ends in a hero 's ordinary world , but the quest passes through an unfamiliar , special world . along the way , there are some key events . think about your favorite book or movie . does it follow this pattern ? status quo , that 's where we start . 1:00 : call to adventure . the hero receives a mysterious message . an invitation , a challenge ? 2:00 : assistance the hero needs some help , probably from someone older , wiser . 3:00 : departure the hero crosses the threshold from his normal , safe home , and enters the special world and adventure . we 're not in kansas anymore . 4:00 : trials being a hero is hard work : our hero solves a riddle , slays a monster , escapes from a trap . 5:00 : approach it 's time to face the biggest ordeal , the hero 's worst fear . ( roar ) 6:00 : crisis this is the hero 's darkest hour . he faces death and possibly even dies , only to be reborn . 7:00 : treasure ( roar ) as a result , the hero claims some treasure , special recognition , or power . 8:00 : result this can vary between stories . do the monsters bow down before the hero , or do they chase him as he flees from the special world ? 9:00 : return after all that adventure , the hero returns to his ordinary world . 10:00 : new life this quest has changed the hero ; he has outgrown his old life . 11:00 : resolution all the tangled plot lines get straightened out . 12:00 : status quo , but upgraded to a new level . nothing is quite the same once you are a hero . many popular books and movies follow this ancient formula pretty closely . but let 's see how well `` the hunger games '' fits the hero 's journey template . when does katniss everdeen hear her call to adventure that gets the story moving ? when her sister 's name is called from the lottery . how about assistance ? is anyone going to help her on her adventure ? haymitch . what about departure ? does she leave her ordinary world ? she gets on a train to the capital . ok , so you get the idea . what do you have in common with harry potter , katniss everdeen , and frodo ? well , you 're human , just like them . the hero 's journey myth exists in all human cultures and keeps getting updated , because we humans reflect on our world through symbolic stories of our own lives . you leave your comfort zone , have an experience that transforms you , and then you recover and do it again . you do n't literally slay dragons or fight voldemort , but you face problems just as scary . joseph campbell said , `` in the cave you fear to enter lies the treasure you seek . '' what is the symbolic cave you fear to enter ? auditions for the school play ? baseball tryouts ? love ? watch for this formula in books , movies , and tv shows you come across . you will certainly see it again . but also be sensitive to it in your own life . listen for your call to adventure . accept the challenge . conquer your fear and claim the treasure you seek . and then , do it all over again .
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along the way , there are some key events . think about your favorite book or movie . does it follow this pattern ?
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think of your favorite book or movie . does it follow ( parts of ) the hero ’ s journey pattern ? explain .
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translator : andrea mcdonough reviewer : bedirhan cinar every cell in your body is separated from those around it by its outermost layer , its membrane . a cell membrane must be both sturdy and flexible . imagine a membrane made of metal - great at keeping the cell 's guts inside , but horrible at letting materials flow in and out . but a membrane made of fishnet stocking would go too far in the opposite direction - leaky , but easily torn . so , the ideal membrane falls somewhere in the middle . over the past few centuries , we 've learned a lot about the way membranes work . the tale starts in the late 1800 's when , according to legend , a german woman named agnes pockels was doing dishes . her observation , that not all detergents dissolve grease in the same way , piqued her curiosity , so she made careful measurements of the size of soapy films that formed on the surface of a metal tray filled with water . later , in the 1920 's , ge scientists irving langmuir and katharine blodgett reexamined the problem with a more elaborate contraption and found that those tiny slicks were in fact a single layer of oil molecules . each oil molecule has one side that loves water and floats on the surface , and one side that loathes water and protrudes into the air . so what does it have to do with cell membranes ? well , at the turn of the 20th century , chemists charles overton and hans meyer demonstrated that the cell membrane is composed of substances that , like oil , have a water-loving part and a water-loathing part . we now call these substances lipids . in 1925 , two scientists , evert gorter and francois grendel , pushed our understanding further . they designed an experiment meant to test whether cell membranes are made of only one layer of lipids , a monolayer , or two layers stacked on top of one another , called a bilayer . gorter and grendel drew blood from a dog , a sheep , a rabbit , a goat , a guinea pig , and human volunteers . from each of these samples , they extracted all the lipids from all the red blood cells and placed a few drops of this extract on a tray of water . true to form , the lipids , like oil , spread out into a monolayer , whose size gorter and grendel could measure . if they compared the surface area of that monolayer to the surface area to the intact red blood cells , they 'd be able to tell whether the red blood cell membrane is one or two layers thick . to understand the design of their experiment , imagine looking down at a sandwich . if you measure the surface area of what you see , you 'll get the dimensions of a single slice of bread even though there are two slices , one stacked perfectly atop the other . but , if you open the sandwich and place the two slices side by side , you get twice the surface area . the gorter and grendel experiment is basically the same idea . the open sandwich is the monolayer formed by extracted cellular lipids spreading out into a sheet . the closed sandwich is the intact red blood cell membrane . low and behold , they observed a two-to-one ratio , proving beyond the shadow of a doubt that a cell membrane is a bilayer , which when unstacked , yields a monolayer twice its size . so almost 30 years before the double-helix structure of dna was elucidated , a single experiment involving fancy versions of household materials enabled deep insight into the basic architecture of the cell .
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well , at the turn of the 20th century , chemists charles overton and hans meyer demonstrated that the cell membrane is composed of substances that , like oil , have a water-loving part and a water-loathing part . we now call these substances lipids . in 1925 , two scientists , evert gorter and francois grendel , pushed our understanding further .
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what do we call molecules that have a hydrophilic head and a hydrophobic tail ?
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( music ) esteemed members of the jury , i submit the following words for immediate and violent execution and extraction from our vocabularies , to be locked away forever , if you would prefer . these words i present to you are `` good '' and `` bad . '' these words have served as treacherous liars for eternity . these two words have worked in tandem to produce vague and bland sentences that have crippled the creativity of humanity . these two deceptively tiny words stifle real description and honest communication . look at them , just sitting there on this page , all smug and satisfied with their work . how dare they ? you serve no purpose in our world , and we must rid ourselves of your influence . we must replace these two words with the truth , with phrases that include adequate and sincere adjectives . i 'll offer you `` radiant , '' `` stupefying , '' `` awful , '' `` gut-wrenching . '' these choices create clarity and depth . `` good '' and `` bad '' only provide gray vagueness . we must demand color ! we should even use winding similes and metaphors , where appropriate . we have to do whatever we can and should to make our real sentiments known . `` good '' and `` bad '' will no longer be our go-to words that we rely on when we are too afraid or too languid to express our real thoughts . ladies and gentlemen of the jury , i implore you to deliver a verdict of guilty and send these words to their rightful fate . now imagine a world without these two words . imagine a world where real description is required , digging further into our vocabulary than just a monosyllabic effort to get away with not being honest , impactful , creative . how does my hair look ? good . what is that ? a dull attempt not to be honest ? perhaps my hair looks like a hideous mess of tangles and bald spots . yet someone does not want to be honest , and offers the quick fix `` good , '' to try and mask the truth and send me hurling into the evening with a plop of disorganized tresses . this will not do . perhaps my hair looks like an amazing glossy sculpture that frames my face perfectly , and lends an air of magic to the night . well , `` good '' just does n't cut it . i wo n't take any more of this formless , lifeless description . i will not take these lies , and neither should you . a doctor asks you how you feel . `` i feel bad . '' heresy ! the doctor , based on this paltry report , could conclude that you have brain cancer or the flu or rabies . you owe it to yourself and the possible misdiagnosis of your life to be honest about exactly how you feel . `` i feel like a herd of wombats has taken up in my chest . '' a-ha ! there we have it . an accurate description . now the doctor has some real evidence to work with in order to assist you . we have become addicted to the numbness that `` good '' and `` bad '' have created . we have become linguistic slobs , churning out `` good '' and `` bad '' wherever we are too lazy to allow our minds to communicate with creativity and specification . you look good , you sound bad , this tastes good , the weather looks bad . lie after lie , repeating this verbal gray , this sloshy mush , this fuzzy picture that reflects no real truth . replace them with grittier , exact terms that have been buried in our lexis , waiting to see daylight . no longer does the weather look good or bad , the weather looks ominous or exhilarating . nothing tastes good or bad . it tastes like pillows of sparkles or old shoe and dung . no more of sounding good or bad . you sound like lilting baby laughter or ogres marching to war . dear god , you do not look good or bad . you look like a feathery angel or a morose faun . today , you look at these two words , `` good '' and `` bad , '' examine them closely . because behind their seemingly unassuming visages reside two deceitful offerings that smother the truth . these words are liars . these words must be stopped . remove them from our language so that honesty can return to our communication . ladies and gentlemen , if i say to you that you have been a good jury , you will take the compliment , make your decision and go on about your day . but if i say to you that you are an honorable jury , and that i hope your unshakeable determination to better the vocabulary of humanity will result in finding `` good '' and `` bad '' guilty , you will recognize the ingenuity of this argument and find `` good '' and `` bad '' guilty . ( music )
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a doctor asks you how you feel . `` i feel bad . '' heresy !
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instead of `` i feel bad , '' what does neel suggest one say to the doctor to describe exactly how he/she feels ?
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when you think of archimedes ' `` eureka ! '' moment , you probably think of this . as it turns out , it may have been more like this . in the third century bc , hieron , king of the sicilian city of syracuse , chose archimedes to supervise an engineering project of unprecedented scale . hieron commissioned a sailing vessel 50 times bigger than a standard ancient warship , named the syracusia after his city . hieron wanted to construct the largest ship ever , which was destined to be given as a present for egypt 's ruler , ptolemy . but could a boat the size of a palace possibly float ? in archimedes 's day , no one had attempted anything like this . it was like asking , `` can a mountain fly ? '' king hieron had a lot riding on that question . hundreds of workmen were to labor for years on constructing the syracusia out of beams of pine and fir from mount etna , ropes from hemp grown in spain , and pitch from france . the top deck , on which eight watchtowers were to stand , was to be supported not by columns , but by vast wooden images of atlas holding the world on his shoulders . on the ship 's bow , a massive catapult would be able to fire 180 pound stone missiles . for the enjoyment of its passengers , the ship was to feature a flower-lined promenade , a sheltered swimming pool , and bathhouse with heated water , a library filled with books and statues , a temple to the goddess aphrodite , and a gymnasium . and just to make things more difficult for archimedes , hieron intended to pack the vessel full of cargo : 400 tons of grain , 10,000 jars of pickled fish , 74 tons of drinking water , and 600 tons of wool . it would have carried well over a thousand people on board , including 600 soldiers . and it housed 20 horses in separate stalls . to build something of this scale , only for that to sink on its maiden voyage ? well , let 's just say that failure would n't have been a pleasant option for archimedes . so he took on the problem : will it sink ? perhaps he was sitting in the bathhouse one day , wondering how a heavy bathtub can float , when inspiration came to him . an object partially immersed in a fluid is buoyed up by a force equal to the weight of the fluid displaced by the object . in other words , if a 2,000 ton syracusia displaced exactly 2,000 tons of water , it would just barely float . if it displaced 4,000 tons of water , it would float with no problem . of course , if it only displaced 1,000 tons of water , well , hieron would n't be too happy . this is the law of buoyancy , and engineers still call it archimedes ' principle . it explains why a steel supertanker can float as easily as a wooden rowboat or a bathtub . if the weight of water displaced by the vessel below the keel is equivalent to the vessel 's weight , whatever is above the keel will remain afloat above the waterline . this sounds a lot like another story involving archimedes and a bathtub , and it 's possible that 's because they 're actually the same story , twisted by the vagaries of history . the classical story of archimedes ' eureka ! and subsequent streak through the streets centers around a crown , or corona in latin . at the core of the syracusia story is a keel , or korone in greek . could one have been mixed up for the other ? we may never know . on the day the syracusia arrived in egypt on its first and only voyage , we can only imagine how residents of alexandria thronged the harbor to marvel at the arrival of this majestic , floating castle . this extraordinary vessel was the titanic of the ancient world , except without the sinking , thanks to our pal , archimedes .
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when you think of archimedes ' `` eureka ! '' moment , you probably think of this .
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does the design of a huge ship explain archimedes ’ eureka moment better than the measurement of a crown ’ s density ?
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today we 're talking about weird materials that we use in space , in robots and in your mouth . i 'm talking about shape memory alloys . like the name says , these are metals that remember different shapes . to understand how these metals work , we 've got to talk about atoms and organizing . let 's talk about atoms first . atoms are tiny bits of matter that you can not see with your eye yet they make up everything in our world , from the chair that you 're sitting on to your cell phone . atoms have some surprising ways of behaving too . we 'll talk about that shortly . now , how big is an atom ? well , imagine pulling one of your hairs out of your head and whittling it like a stick 100,000 times . one of those shavings would be the width of an atom . they 're that small . now let 's talk about atoms and organizing . you may not know this , but atoms arrange themselves similar to the way we humans arrange ourselves . sometimes they sit in rows , like we do on a bus or an airplane . we call that seating arrangement a phase . other times they sit diagonal from each other , sort of like seats in a movie theater or sports stadium . this is another phase . when atoms move from one seating to another this is called a phase change . phase changes are all around us . you may already know about water 's phases : solid , liquid and gas . many other materials have phases like that too . some of them have several solid phases . ok. back to those shape memory alloys we mentioned before . when we say that the metals remember their different shapes , what we 're really saying is they remember different seating arrangements of atoms . when the atoms rearrange , the metal moves from one shape to another . let 's look at a phase change in action . here i have a metal wire that is made out of nickel and titanium . this metal wire is a shape memory alloy , and i 'm going to make it switch between its different shapes using heat from a lighter . watch this . i 'm going to wrap this wire around my finger and then heat it . amazing ! that wire returns to a straight line , when i heat it . let 's try that again . i 'm going to wrap it around my finger , and heat it . yep , that 's still amazing . not only is it amazing , this is weird , because metals generally do n't do that . here 's a paper clip . when i heat it , i get nothing . what we 're seeing is the shape memory wire changing phases when it gets hot . when the wire is cold , atoms are in a diagonal arrangement , like the movie theater seating , we talked about before . we call this a monoclinic arrangement , and scientists will call this phase martensite . when i heated up the wire , the atoms moved into columns like airplane seating . this is a cubic arrangement . scientists will call this phase austenite . so when we added the heat , the atoms shifted positions seamlessly , and they 'll do this forever . they have this coordinated motion , just like members of a tireless marching band . each makes a small shift , but all together those small shifts create a totally different pattern . so that 's pretty cool , but where do we use these materials ? well , if you look in the sky tonight , shape memory alloys are at work - on mars . they 're used to move panels on the mars rover , so that it can study the environment . like our metal straightened when it was heated , the metals holding the panels will move when electrically heated . when we stop heating the shape memory metal , the panel will return back , due to an opposing spring . back on earth , shape memory alloys are used to open up clogged arteries as stents , which are small collapsible springs that force open passages . shape memory alloys are also used to move robots , toy butterflies , teeth in braces , and for a perfect fit every time , shape memory wires are used as underwires in bras . now you know victoria 's secret . by popping a bra into the dryer , it 'll be brand new every time . so whether it 's on mars or in your mouth , small atomic movements can create huge changes , and understanding the way atoms behave allows us to make materials that make our world a better place .
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when i heat it , i get nothing . what we 're seeing is the shape memory wire changing phases when it gets hot . when the wire is cold , atoms are in a diagonal arrangement , like the movie theater seating , we talked about before .
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what kind of invention would you make with shape memory materials if you could get it in any form you wanted ( like wire , sheets , big chunks , or any other way ) ?
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for some , it 's a serious sport . for others , just a way to let loose . but despite its casual association with fun and sun , surfing has a richer and deeper history than many realize . what we today call surfing originated in the polynesian islands of the pacific ocean . we know from various accounts that wave riding was done throughout the polynesian pacific , as well as in west africa and peru . but it was in the hawaiian archipelago in particular that surfing advanced the most , was best documented , and , unlike elsewhere in polynesia , persisted . and for the people of hawaii , wave sliding was not just a recreational activity , but one with spiritual and social significance . like much of hawaiian society , nearly every aspect of surfing was governed by a code of rules and taboos known as kapu . hawaiians made offerings when selecting a tree to carve , prayed for waves with the help of a kahuna , or an expert priest , and gave thanks after surviving a perilous wipeout . certain surf breaks were strickly reserved for the elite . but it was n't just a solemn affair . surfers competed and wagered on who could ride the farthest , the fastest , or catch the biggest wave with superior skill , granting respect , social status , and romantic success . though it was later called the sport of kings , hawaiian men and women of all ages and social classes participated , riding surfboards shaped from koa , breadfruit , or wiliwili trees . many hawaiians road alaia boards , which were thin , midsized , and somewhat resemble today 's shortboards . some mounted paipo boards , short , round-nosed boards on which riders typically lay on their stomachs . but only chieftains could ride the massive olo boards , twice as long as today 's longboards . unlike most modern surfboards , all boards were finless , requiring surfers to drag their hands or feet to turn . we do n't know exactly when wave sliding was invented , but we know that it had already been practiced in polynesia for centuries by the time it was described in 1777 by william anderson , a surgeon on captain cook 's ship `` resolution . '' although anderson was in awe , most of the american christian missionaries who arrived in hawaii several decades later regarded surfing as sinful , and they discouraged it , along with other aspects of native culture . the biggest threat to surfing , however , was the threat to the natives themselves . by 1890 , new illnesses introduced by europeans and americans had decimated the hawaiian people , leaving fewer than 40,000 from a pre-contact population that may have exceeded 800,000 . at the same time , foreign influence grew with white settlers overthrowing the native monarchy in 1893 , and the u.s. annexing the islands five years later . the end of hawaii 's independence coincided with surfing 's native-led revival , a revival soon exploited by the american colonizers . but first , some hawaiians took surfing overseas . in 1907 , george freeth , the so-called hawaiian wonder , traveled to the west coast and gave surfing demonstrations in southern california . then in 1914 , olympic swimmer duke kahanamoku made his way to australia and new zealand , gliding across the southern pacific waves and attracting rapt audiences wherever he went . shortly before freeth went to california , a south carolinian named alexander hume ford moved to hawaii . after learning to surf , he became a champion of the pastime . but ford may have had unsavory reasons for his enthusiastic efforts to boost the sport . like many settlers , he wanted hawaii to become a u.s. state but was worried about its non-white majority of natives and asian workers . ford thus promoted surfing to attract white americans to hawaii , first as tourists , then as residents . he was helped by numerous writers and filmmakers . ford 's demographic plan would fail miserably . hawaii became a state in 1959 and remains the most racially diverse state in the country . but the promotion of surfing was a far greater success . today , surfing is a multi-billion dollar global industry , with tens of millions of enthusiasts worldwide . and though relatively few of these surfers are aware of the once-crucial wave chants or board carving rituals , hawaiians continue to preserve these traditions nearly washed away by history 's waves .
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the biggest threat to surfing , however , was the threat to the natives themselves . by 1890 , new illnesses introduced by europeans and americans had decimated the hawaiian people , leaving fewer than 40,000 from a pre-contact population that may have exceeded 800,000 . at the same time , foreign influence grew with white settlers overthrowing the native monarchy in 1893 , and the u.s. annexing the islands five years later .
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by 1890 , illnesses introduced by foreigners had killed so many hawaiians that , out of a pre-contact population that may have exceeded 800,000 , approximately _____________ hawaiians remained .
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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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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 .
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stress can increase your risk of a heart attack or stroke by all of the following except :
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more than a century after first emerging into the fog-bound , gas-lit streets of victorian london , sherlock holmes is universally recognizable . even his wardrobe and accessories are iconic : the inverness cape , deerstalker hat , and calabash pipe , and figures such as his best friend and housemate doctor watson , arch-nemesis moriarty , and housekeeper mrs. hudson have become part of the popular consciousness , as have his extraordinary , infallible powers of deduction utilized in the name of the law , his notorious drug use , and his popular catchphrase , `` elementary , my dear watson . '' and yet many of these most recognizable features of holmes do n't appear in arthur conan doyle 's original stories . doyle 's great detective solves crimes in all sorts of ways , not just using deduction . he speculates , and at times even guesses , and regularly makes false assumptions . furthermore , mrs. hudson is barely mentioned , no one says , `` elementary , my dear watson , '' and the detective and his sidekick live apart for much of the time . moriarty , the grand villain , only appears in two stories , the detective 's drug use is infrequent after the first two novels , and holmes is rarely enthralled to the english legal system ; he much prefers enacting his own form of natural justice to sticking to the letter of the law . finally , many of the most iconic elements of the holmesian legend are n't doyle 's either . the deerstalker cap and cape were first imagined by sidney paget , the story 's initial illustrator . the curved pipe was chosen by american actor william gillette so that audiences could more clearly see his face on stage , and the phrase , `` elementary , my dear watson , '' was coined by author and humorist p.g . wodehouse . so who exactly is sherlock holmes ? who 's the real great detective , and where do we find him ? purists might answer that the original sherlock inspired by arthur conan doyle 's university mentor dr. joseph bell is the real one . but the fact remains that that version of sherlock has been largely eclipsed by the sheer volume of interpretation , leaving doyle 's detective largely unrecognizable . so there 's another , more complex , but perhaps more satisfying answer to the question , but to get there , we must first consider the vast body of interpretations of the great detective . since conan doyle 's first story in 1887 , there have been thousands of adaptations of holmes , making him perhaps the most adapted fictional character in the world . that process began with victorian stage adaptations , and accelerated with the emergence of film . there were more than 100 film adaptations of holmes in the first two decades of the 20th century alone . and since then , there have many thousands more in print , and on film , television , stage , and radio . holmes has been reinterpreted by people everywhere , in remarkably different , and often contradictory ways . these adaptations demonstrate both holmes 's popularity and his malleability . for instance , he featured in a number of allied anti-nazi propaganda films during world war ii . and both winston churchill and franklin delano roosevelt were avid enthusiasts , the latter even joining the baker street irregulars , a holmesian appreciation society , and nicknaming one secret service hideout baker street . and yet , at the very same time , holmes also appeared in various german-language film adaptations , some of which were said to have been much-loved favorites of adolf hitler . so let 's return to our question . would the real sherlock holmes please stand up ? the truth is that this world of adaptation has made him into a palimpsest . sherlock is a cultural text , repeatedly altered over time as each new interpretation becomes superimposed over those that proceed it . this means that sherlock continually evolves , embodying ideas and values often far removed from those found in conan doyle . and after each particular story ends , sherlock rises again , a little changed , perhaps , with a new face and fresh mannerisms or turns of phrase , but still essentially sherlock , our sherlock .
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wodehouse . so who exactly is sherlock holmes ? who 's the real great detective , and where do we find him ?
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who was sherlock holmes ’ s best friend and working partner ?
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have you ever sat in a doctor 's office for hours despite having an appointment at a specific time ? has a hotel turned down your reservation because it 's full ? or have you been bumped off a flight that you paid for ? these are all symptoms of overbooking , a practice where businesses and institutions sell or book more than their full capacity . while often infuriating for the customer , overbooking happens because it increases profits while also letting businesses optimize their resources . they know that not everyone will show up to their appointments , reservations , and flights , so they make more available than they actually have to offer . airlines are the classical example , partially because it happens so often . about 50,000 people get bumped off their flights each year . that figure comes at little surprise to the airlines themselves , which use statistics to determine exactly how many tickets to sell . it 's a delicate operation . sell too few , and they 're wasting seats . sell too many , and they pay penalties - money , free flights , hotel stays , and annoyed customers . so here 's a simplified version of how their calculations work . airlines have collected years worth of information about who does and does n't show up for certain flights . they know , for example , that on a particular route , the probability that each individual customer will show up on time is 90 % . for the sake of simplicity , we 'll assume that every customer is traveling individually rather than as families or groups . then , if there are 180 seats on the plane and they sell 180 tickets , the most likely result is that 162 passengers will board . but , of course , you could also end up with more passengers , or fewer . the probability for each value is given by what 's called a binomial distribution , which peaks at the most likely outcome . now let 's look at the revenue . the airline makes money from each ticket buyer and loses money for each person who gets bumped . let 's say a ticket costs $ 250 and is n't exchangeable for a later flight . and the cost of bumping a passenger is $ 800 . these numbers are just for the sake of example . actual amounts vary considerably . so here , if you do n't sell any extra tickets , you make $ 45,000 . if you sell 15 extras and at least 15 people are no shows , you make $ 48,750 . that 's the best case . in the worst case , everyone shows up . 15 unlucky passengers get bumped , and the revenue will only be $ 36,750 , even less than if you only sold 180 tickets in the first place . but what matters is n't just how good or bad a scenario is financially , but how likely it is to happen . so how likely is each scenario ? we can find out by using the binomial distribution . in this example , the probability of exactly 195 passengers boarding is almost 0 % . the probability of exactly 184 passengers boarding is 1.11 % , and so on . multiply these probabilities by the revenue for each case , add them all up , and subtract the sum from the earnings by 195 sold tickets , and you get the expected revenue for selling 195 tickets . by repeating this calculation for various numbers of extra tickets , the airline can find the one likely to yield the highest revenue . in this example , that 's 198 tickets , from which the airline will probably make $ 48,774 , almost 4,000 more than without overbooking . and that 's just for one flight . multiply that by a million flights per airline per year , and overbooking adds up fast . of course , the actual calculation is much more complicated . airlines apply many factors to create even more accurate models . but should they ? some argue that overbooking is unethical . you 're charging two people for the same resource . of course , if you 're 100 % sure someone wo n't show up , it 's fine to sell their seat . but what if you 're only 95 % sure ? 75 % ? is there a number that separates being unethical from being practical ?
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but should they ? some argue that overbooking is unethical . you 're charging two people for the same resource .
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overbooking is :
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packed inside every cell in your body is a set of genetic instructions , 3.2 billion base pairs long . deciphering these directions would be a monumental task but could offer unprecedented insight about the human body . in 1990 , a consortium of 20 international research centers embarked on the world 's largest biological collaboration to accomplish this mission . the human genome project proposed to sequence the entire human genome over 15 years with $ 3 billion of public funds . then , seven years before its scheduled completion , a private company called celera announced that they could accomplish the same goal in just three years and at a fraction of the cost . the two camps discussed a joint venture , but talks quickly fell apart as disagreements arose over legal and ethical issues of genetic property . and so the race began . though both teams used the same technology to sequence the entire human genome , it was their strategies that made all the difference . their paths diverged in the most critical of steps : the first one . in the human genome project 's approach , the genome was first divided into smaller , more manageable chunks about 150,000 base pairs long that overlapped each other a little bit on both ends . each of these fragments of dna was inserted inside a bacterial artificial chromosome where they were cloned and fingerprinted . the fingerprints showed scientists where the fragments overlapped without knowing the actual sequence . using the overlapping bits as a guide , the researchers marked each fragment 's place in the genome to create a contiguous map , a process that took about six years . the cloned fragments were sequenced in labs around the world following one of the project 's two major principles : that collaboration on our shared heritage was open to all nations . in each case , the fragments were arbitrarily broken up into small , overlapping pieces about 1,000 base pairs long . then , using a technology called the sanger method , each piece was sequenced letter by letter . this rigorous map-based approach called hierarchical shotgun sequencing minimized the risk of misassembly , a huge hazard of sequencing genomes with many repetitive portions , like the human genome . the consortium 's `` better safe than sorry '' approach contrasted starkly with celera 's strategy called whole genome shotgun sequencing . it hinged on skipping the mapping phase entirely , a faster , though foolhardy , approach according to some . the entire genome was directly chopped up into a giant heap of small , overlapping bits . once these bits were sequenced via the sanger method , celera would take the formidable risk of reconstructing the genome using just the overlaps . but perhaps their decision was n't such a gamble because guess whose freshly completed map was available online for free ? the human genome consortium , in accordance with the project 's second major principle which held that all of the project 's data would be shared publicly within 24 hours of collection . so in 1998 , scientists around the world were furiously sequencing lines of genetic code using the tried and true , yet laborious , sanger method . finally , after three exhausting years of continuous sequencing and assembling , the verdict was in . in february 2001 , both groups simultaneously published working drafts of more than 90 % of the human genome , several years ahead of the consortium 's schedule . the race ended in a tie . the human genome project 's practice of immediately sharing its data was an unusual one . it is more typical for scientists to closely guard their data until they are able to analyze it and publish their conclusions . instead , the human genome project accelerated the pace of research and created an international collaboration on an unprecedented scale . since then , robust investment in both the public and private sector has led to the identification of many disease related genes and remarkable advances in sequencing technology . today , a person 's genome can be sequenced in just a few days . however , reading the genome is only the first step . we 're a long way away from understanding what most of our genes do and how they are controlled . those are some of the challenges for the next generation of ambitious research initiatives .
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their paths diverged in the most critical of steps : the first one . in the human genome project 's approach , the genome was first divided into smaller , more manageable chunks about 150,000 base pairs long that overlapped each other a little bit on both ends . each of these fragments of dna was inserted inside a bacterial artificial chromosome where they were cloned and fingerprinted .
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a single human genome is approximately _____ base pairs long .
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back in new york , i am the head of development for a non-profit called robin hood . when i 'm not fighting poverty , i 'm fighting fires as the assistant captain of a volunteer fire company . now in our town , where the volunteers supplement a highly skilled career staff , you have to get to the fire scene pretty early to get in on any action . i remember my first fire . i was the second volunteer on the scene , so there was a pretty good chance i was going to get in . but still it was a real footrace against the other volunteers to get to the captain in charge to find out what our assignments would be . when i found the captain , he was having a very engaging conversation with the homeowner , who was surely having one of the worst days of her life . here it was , the middle of the night , she was standing outside in the pouring rain , under an umbrella , in her pajamas , barefoot , while her house was in flames . the other volunteer who had arrived just before me -- let 's call him lex luther -- ( laughter ) got to the captain first and was asked to go inside and save the homeowner 's dog . the dog ! i was stunned with jealousy . here was some lawyer or money manager who , for the rest of his life , gets to tell people that he went into a burning building to save a living creature , just because he beat me by five seconds . well , i was next . the captain waved me over . he said , `` bezos , i need you to go into the house . i need you to go upstairs , past the fire , and i need you to get this woman a pair of shoes . '' ( laughter ) i swear . so , not exactly what i was hoping for , but off i went -- up the stairs , down the hall , past the 'real ' firefighters , who were pretty much done putting out the fire at this point , into the master bedroom to get a pair of shoes . now i know what you 're thinking , but i 'm no hero . ( laughter ) i carried my payload back downstairs where i met my nemesis and the precious dog by the front door . we took our treasures outside to the homeowner , where , not surprisingly , his received much more attention than did mine . a few weeks later , the department received a letter from the homeowner thanking us for the valiant effort displayed in saving her home . the act of kindness she noted above all others : someone had even gotten her a pair of shoes . ( laughter ) in both my vocation at robin hood and my avocation as a volunteer firefighter , i am witness to acts of generosity and kindness on a monumental scale , but i 'm also witness to acts of grace and courage on an individual basis . and you know what i 've learned ? they all matter . so as i look around this room at people who either have achieved , or are on their way to achieving , remarkable levels of success , i would offer this reminder : do n't wait . do n't wait until you make your first million to make a difference in somebody 's life . if you have something to give , give it now . serve food at a soup kitchen . clean up a neighborhood park . be a mentor . not every day is going to offer us a chance to save somebody 's life , but every day offers us an opportunity to affect one . so get in the game . save the shoes . thank you . ( applause ) bruno giussani : mark , mark , come back . ( applause ) mark bezos : thank you .
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do n't wait until you make your first million to make a difference in somebody 's life . if you have something to give , give it now . serve food at a soup kitchen .
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the mission statement of the oklahoma state firefighters association looks something like this : `` we protect lives , property , and the environment , with compassion , vigilance , and dedication to excellence . '' why do heroes often share similar character traits ?
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