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so you just strained a muscle and the inflammation is unbearable . you wish you had something ice-cold to dull the pain , but to use an ice pack , you would have had to put it in the freezer hours ago . fortunately , there 's another option . a cold pack can be left at room temperature until the moment you need it , then just snap it as instructed and within seconds you 'll feel the chill . but how can something go from room temperature to near freezing in such a short time ? the answer lies in chemistry . your cold pack contains water and a solid compound , usually ammonium nitrate , in different compartments separated by a barrier . when the barrier is broken , the solid dissolves causing what 's known as an endothermic reaction , one that absorbs heat from its surroundings . to understand how this works , we need to look at the two driving forces behind chemical processes : energetics and entropy . these determine whether a change occurs in a system and how energy flows if it does . in chemistry , energetics deals with the attractive and repulsive forces between particles at the molecular level . this scale is so small that there are more water molecules in a single glass than there are known stars in the universe . and all of these trillions of molecules are constantly moving , vibrating and rotating at different rates . we can think of temperature as a measurement of the average motion , or kinetic energy , of all these particles , with an increase in movement meaning an increase in temperature , and vice versa . the flow of heat in any chemical transformation depends on the relative strength of particle interactions in each of a substance 's chemical states . when particles have a strong mutual attractive force , they move rapidly towards one another , until they get so close , that repulsive forces push them away . if the initial attraction was strong enough , the particles will keep vibrating back and forth in this way . the stronger the attraction , the faster their movement , and since heat is essentially motion , when a substance changes to a state in which these interactions are stronger , the system heats up . but our cold packs do the opposite , which means that when the solid dissolves in the water , the new interactions of solid particles and water molecules with each other are weaker than the separate interactions that existed before . this makes both types of particles slow down on average , cooling the whole solution . but why would a substance change to a state where the interactions were weaker ? would n't the stronger preexisting interactions keep the solid from dissolving ? this is where entropy comes in . entropy basically describes how objects and energy are distributed based on random motion . if you think of the air in a room , there are many different possible arrangements for the trillions of particles that compose it . some of these will have all the oxygen molecules in one area , and all the nitrogen molecules in another . but far more will have them mixed together , which is why air is always found in this state . now , if there are strong attractive forces between particles , the probability of some configurations can change even to the point where the odds do n't favor certain substances mixing . oil and water not mixing is an example . but in the case of the ammonium nitrate , or other substance in your cold pack , the attractive forces are not strong enough to change the odds , and random motion makes the particles composing the solid separate by dissolving into the water and never returning to their solid state . to put it simply , your cold pack gets cold because random motion creates more configurations where the solid and water mix together and all of these have even weaker particle interaction , less overall particle movement , and less heat than there was inside the unused pack . so while the disorder that can result from entropy may have caused your injury in the first place , its also responsible for that comforting cold that soothes your pain .

but why would a substance change to a state where the interactions were weaker ? would n't the stronger preexisting interactions keep the solid from dissolving ? this is where entropy comes in . entropy basically describes how objects and energy are distributed based on random motion . if you think of the air in a room , there are many different possible arrangements for the trillions of particles that compose it .

there are some solids that do not dissolve in water despite the fact that the interactions are stronger if they are dissolved . build an explanation based on entropy for why these substances do not dissolve .

it 's the first sense you use when you 're born . one out of every fifty of your genes is dedicated to it . it must be important , right ? okay , take a deep breath through your nose . it 's your sense of smell , and it 's breathtakingly powerful . as an adult , you can distinguish about 10,000 different smells . here 's how your nose does it . smell starts when you sniff molecules from the air into your nostrils . 95 % of your nasal cavity is used just to filter that air before it hits your lungs . but at the very back of your nose is a region called the olfactory epithelium , a little patch of skin that 's key to everything you smell . the olfactory epithelium has a layer of olfactory receptor cells , special neurons that sense smells , like the taste buds of your nose . when odor molecules hit the back of your nose , they get stuck in a layer of mucus covering the olfactory epithelium . as they dissolve , they bind to the olfactory receptor cells , which fire and send signals through the olfactory tract up to your brain . as a side note , you can tell a lot about how good an animal 's sense of smell is by the size of its olfactory epithelium . a dog 's olfactory epithelium is 20 times bigger than your puny human one . but there 's still a lot we do n't know about this little patch of cells , too . for example , our olfactory epithelium is pigmented , and scientists do n't really know why . but how do you actually tell the difference between smells ? it turns out that your brain has 40 million different olfactory receptor neurons , so odor a might trigger neurons 3 , 427 , and 988 , and odor b might trigger neurons 8 , 76 , and 2,496,678 . all of these different combinations let you detect a staggeringly broad array of smells . olfactory neurons are always fresh and ready for action . they 're the only neuron in the body that gets replaced regularly , every four to eight weeks . once they are triggered , the signal travels through a bundle called the olfactory tract to destinations all over your brain , making stops in the amygdala , the thalamus , and the neocortex . this is different from how sight and sound are processed . each of those signals goes first to a relay center in the middle of the cerebral hemisphere and then out to other regions of the brain . but smell , because it evolved before most of your other senses , takes a direct route to these different regions of the brain , where it can trigger your fight-or-flight response , help you recall memories , or make your mouth water . but even though we 've all got the same physiological set-up , two nostrils and millions of olfactory neurons , not everybody smells the same things . one of the most famous examples of this is the ability to smell so-called `` asparagus pee . '' for about a quarter of the population , urinating after eating asparagus means smelling a distinct odor . the other 75 % of us do n't notice . and this is n't the only case of smells differing from nose to nose . for some people , the chemical androstenone smells like vanilla ; to others , it smells like sweaty urine , which is unfortunate because androstenone is commonly found in tasty things like pork . so with the sweaty urine smellers in mind , pork producers will castrate male pigs to stop them from making androstenone . the inability to smell a scent is called anosmia , and there are about 100 known examples . people with allicin anosmia ca n't smell garlic . those with eugenol anosmia ca n't smell cloves . and some people ca n't smell anything at all . this kind of full anosmia could have several causes . some people are born without a sense of smell . others lose it after an accident or during an illness . if the olfactory epithelium gets swollen or infected , it can hamper your sense of smell , something you might have experienced when you were sick . not being able to smell anything can mess with your other senses , too . many people who ca n't smell at all also ca n't really taste the same way the rest of us do . it turns out that how something tastes is closely related to how it smells . as you chew your food , air is pushed up your nasal passage , carrying with it the smell of your food . those scents hit your olfactory epithelium and tell your brain a lot about what you 're eating . without the ability to smell , you lose the ability to taste anything more complicated than the five tastes your taste buds can detect : sweet , salty , bitter , sour , and savory . so , the next time you smell exhaust fumes , salty sea air , or roast chicken , you 'll know exactly how you 've done it and , perhaps , be a little more thankful that you can .

as a side note , you can tell a lot about how good an animal 's sense of smell is by the size of its olfactory epithelium . a dog 's olfactory epithelium is 20 times bigger than your puny human one . but there 's still a lot we do n't know about this little patch of cells , too .

a dog 's olfactory epithelium is ________ times larger than a human 's .

we live in an age of protest . on campuses and public squares , on streets and social media , protesters around the world are challenging the status quo . protest can thrust issues onto the national or global agenda , it can force out tyrants , it can activate people who have long been on the sidelines of civic life . while protest is often necessary , is it sufficient ? consider the arab spring . all across the middle east , citizen protesters were able to topple dictators . afterwards , though , the vacuum was too often filled by the most militant and violent . protest can generate lasting positive change when it 's followed by an equally passionate effort to mobilize voters , to cast ballots , to understand government , and to make it more inclusive . so here are three core strategies for peacefully turning awareness into action and protest into durable political power . first , expand the frame of the possible , second , choose a defining fight , and third , find an early win . let 's start with expanding the frame of the possible . how often have you heard in response to a policy idea , `` that 's just never going to happen '' ? when you hear someone say that , they 're trying to define the boundaries of your civic imagination . the powerful citizen works to push those boundaries outward , to ask what if - what if it were possible ? what if enough forms of power - people power , ideas , money , social norms - were aligned to make it happen ? simply asking that question and not taken as given all the givens of conventional politics is the first step in converting protest to power . but this requires concreteness about what it would look like to have , say , a radically smaller national government , or , by contrast , a big single-payer healthcare system , a way to hold corporations accountable for their misdeeds , or , instead , a way to free them from onerous regulations . this brings us to the second strategy , choosing a defining fight . all politics is about contrasts . few of us think about civic life in the abstract . we think about things in relief compared to something else . powerful citizens set the terms of that contrast . this does n't mean being uncivil . it simply means thinking about a debate you want to have on your terms over an issue that captures the essence of the change you want . this is what the activists pushing for a $ 15 minimum wage in the u.s. have done . they do n't pretend that $ 15 by itself can fix inequality , but with this ambitious and contentious goal , which they achieved first in seattle and then beyond , they have forced a bigger debate about economic justice and prosperity . they 've expanded the frame of the possible , strategy one , and created a sharp emblematic contrast , strategy two . the third key strategy , then , is to seek and achieve an early win . an early win , even if it 's not as ambitious as the ultimate goal , creates momentum , which changes what people think is possible . the solidarity movement , which organized workers in cold war poland emerged just this way , first , with local shipyard strikes in 1980 that forced concessions , then , over the next decade , a nationwide effort that ultimately helped topple poland 's communist government . getting early wins sets in motion a positive feedback loop , a contagion , a belief , a motivation . it requires pressuring policymakers , using the media to change narrative , making arguments in public , persuading skeptical neighbors one by one by one . none of this is as sexy as a protest , but this is the history of the u.s. civil rights movement , of indian independence , of czech self-determination . not the single sudden triumph , but the long , slow slog . you do n't have to be anyone special to be part of this grind , to expand the frame of the possible , to pick a defining fight , or to secure an early win . you just have to be a participant and to live like a citizen . the spirit of protest is powerful . so is showing up after the protest . you can be the co-creator of what comes next .

but this requires concreteness about what it would look like to have , say , a radically smaller national government , or , by contrast , a big single-payer healthcare system , a way to hold corporations accountable for their misdeeds , or , instead , a way to free them from onerous regulations . this brings us to the second strategy , choosing a defining fight . all politics is about contrasts .

which of the following statements should be considered when “ choosing a defining fight ” ?

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 )

ok , i 'm going to be stumped on this . anybody knows why we vote on tuesdays ? jacob soboroff : do you happen to know ?

why do americans vote on tuesdays ?

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 .

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 .

icecube is built at the south pole because we needed a cubic kilometer of a transparent material . can you think of other places where a detector such as icecube could be built ?

translator : bedirhan cinar my wife is pregnant right now with our first child , and when people see her with her big baby bump , the first question people ask , almost without fail , is , `` is it a boy or is it a girl ? '' now , there are some assumptions behind that question that we take for granted because of our familiarity with our own human biology . for human babies , we take it for granted that there 's a 50/50 chance of either answer , boy or girl . but why is it that way ? well , the answer depends on the sex determination system that has evolved for our species . you see , for most mammals , the sex of a baby is determined genetically with the xy chromosome system . mammals have a pair of sex chromosomes , one passed down from mom , and one from dad . a pair of x 's gives us a girl , and an x and a y together gives us a boy . since females only have x 's to pass on in their egg cells , and males can give either an x or a y in their sperm cells , the sex is determined by the father and the chance of producing a male or a female is 50/50 . this system has worked well for mammals , but throughout the tree of life , we can see other systems that have worked just as well for other animals . there are other groups of animals that also have genetic sex determination , but their systems can be pretty different from ours . birds and some reptiles have their sex genetically determined , but instead of the sex being determined by dad , their sex is determined by mom . in those groups , a pair of z sex chromosomes produces a male , so these males only have z 's to give . however , in these animals , one z and one w chromosome together , as a pair , produces a female . in this system , the chance of a male or a female is still 50/50 , it just depends on whether mom puts a z or a w into her egg . certain groups have taken genetic sex determination in completely other directions . ants , for example , have one of the most interesting systems for determining sex , and because of it , if you are a male ant , you do not have a father . in an ant colony , there are dramatic divisions of labor . there are soldiers that defend the colony , there are workers that collect food , clean the nest and care for the young , and there 's a queen and a small group of male reproductives . now , the queen will mate and then store sperm from the males . and this is where the system gets really interesting . if the queen uses the stored sperm to fertilize an egg , then that egg will grow up to become female . however , if she lays an egg without fertilizing it , then that egg will still grow up to be an ant , but it will always be a male . so you see , it 's impossible for male ants to have fathers . and male ants live their life like this , with only one copy of every gene , much like a walking sex cell . this system is called a haplodiploid system , and we see it not only in ants , but also in other highly social insects like bees and wasps . since our own sex is determined by genes , and we do know of these other animals that have their sex determined by genes , it 's easy to assume that for all animals the sex of their babies still must be determined by genetics . however , for some animals , the question of whether it will be a boy or a girl has nothing to do with genes at all , and it can depend on something like the weather . these are animals like alligators and most turtles . in these animals , the sex of an embryo in a developing egg is determined by the temperature . in these species , the sex of the baby is not yet determined when the egg is laid , and it remains undetermined until sometime in the middle of the overall development period , when a critical time is reached . and during this time , the sex is completely determined by temperature in the nest . in painted turtles , for example , warm temperatures above the critical temperature will produce females within the eggs , and cool temperatures will produce a male . i 'm not sure who came up with this mnemonic , but you can remember that when it comes to painted turtles , they are all hot chicks and cool dudes . for some tropical fish , the question of will it be a boy or will it be a girl is n't settled until even later in life . you see , clownfish all start out their lives as males , however , as they mature , they become female . they also spend their lives in small groups with a strict dominance hierarchy where only the most dominant male and female reproduce . and amazingly , if the dominant female in the group dies , the largest and most dominant male will then quickly become female and take her place , and all of the other males will move up one rank in the hierarchy . in another very different ocean animal , the green spoonworm , the sex of the babies is determined by a completely different aspect of the environment . for this species , it is simply a matter of where a larva happens to randomly fall on the sea floor . if a larva lands on the open sea floor , then it will become a female . but if it lands on top of a female , then it will become a male . so for some species , the question of boy or girl is answered by genetics . for others , it 's answered by the environment . and for others still , they do n't even bother with the question at all . take whiptail lizards , for example . for those desert lizards , the answer is easy . it 's a girl . it 's always a girl . they are a nearly all-female species , and although they still lay eggs , these eggs hatch out female clones of themselves . so will it be a girl or will it be a boy ? throughout the entire animal kingdom , it does really all depend on the system of sex determination . for humans , that system is a genetic xy system . and for me and my wife , we found out it 's going to be a baby boy . ( kiss )

and during this time , the sex is completely determined by temperature in the nest . in painted turtles , for example , warm temperatures above the critical temperature will produce females within the eggs , and cool temperatures will produce a male . i 'm not sure who came up with this mnemonic , but you can remember that when it comes to painted turtles , they are all hot chicks and cool dudes .

for painted turtles , warm temperatures in the nest during the critical time of development will produce :

as the story goes , the legendary marksman william tell was forced into a cruel challenge by a corrupt lord . william 's son was to be executed unless william could shoot an apple off his head . william succeeded , but let 's imagine two variations on the tale . in the first variation , the lord hires a bandit to steal william 's trusty crossbow , so he is forced to borrow an inferior one from a peasant . however , the borrowed crossbow is n't adjusted perfectly , and william finds that his practice shots cluster in a tight spread beneath the bullseye . fortunately , he has time to correct for it before it 's too late . variation two : william begins to doubt his skills in the long hours before the challenge and his hand develops a tremor . his practice shots still cluster around the apple but in a random pattern . occasionally , he hits the apple , but with the wobble , there is no guarantee of a bullseye . he must settle his nervous hand and restore the certainty in his aim to save his son . at the heart of these variations are two terms often used interchangeably : accuracy and precision . the distinction between the two is actually critical for many scientific endeavours . accuracy involves how close you come to the correct result . your accuracy improves with tools that are calibrated correctly and that you 're well-trained on . precision , on the other hand , is how consistently you can get that result using the same method . your precision improves with more finely incremented tools that require less estimation . the story of the stolen crossbow was one of precision without accuracy . william got the same wrong result each time he fired . the variation with the shaky hand was one of accuracy without precision . william 's bolts clustered around the correct result , but without certainty of a bullseye for any given shot . you can probably get away with low accuracy or low precision in everyday tasks . but engineers and researchers often require accuracy on microscopic levels with a high certainty of being right every time . factories and labs increase precision through better equipment and more detailed procedures . these improvements can be expensive , so managers must decide what the acceptable uncertainty for each project is . however , investments in precision can take us beyond what was previously possible , even as far as mars . it may surprise you that nasa does not know exactly where their probes are going to touch down on another planet . predicting where they will land requires extensive calculations fed by measurements that do n't always have a precise answer . how does the martian atmosphere 's density change at different elevations ? what angle will the probe hit the atmosphere at ? what will be the speed of the probe upon entry ? computer simulators run thousands of different landing scenarios , mixing and matching values for all of the variables . weighing all the possibilities , the computer spits out the potential area of impact in the form of a landing ellipse . in 1976 , the landing ellipse for the mars viking lander was 62 x 174 miles , nearly the area of new jersey . with such a limitation , nasa had to ignore many interesting but risky landing areas . since then , new information about the martian atmosphere , improved spacecraft technology , and more powerful computer simulations have drastically reduced uncertainty . in 2012 , the landing ellipse for the curiosity lander was only 4 miles wide by 12 miles long , an area more than 200 times smaller than viking 's . this allowed nasa to target a specific spot in gale crater , a previously un-landable area of high scientific interest . while we ultimately strive for accuracy , precision reflects our certainty of reliably achieving it . with these two principles in mind , we can shoot for the stars and be confident of hitting them every time .

it may surprise you that nasa does not know exactly where their probes are going to touch down on another planet . predicting where they will land requires extensive calculations fed by measurements that do n't always have a precise answer . how does the martian atmosphere 's density change at different elevations ?

write your own example of a scenario that would give you imprecise but accurate measurements .

trillions of bacteria , viruses , and fungi live on or inside of us , and maintaining a good , balanced relationship with them is to our advantage . together , they form the gut microbiome , a rich ecosystem that performs a variety of functions in our bodies . the bacteria in our guts can break down food the body ca n't digest , produce important nutrients , regulate the immune system , and protect against harmful germs . we do n't yet have the blueprint for exactly which good bacteria a robust gut needs , but we do know that it 's important for a healthy microbiome to have a variety of bacterial species . many factors affect our microbiomes , including our environment , medications like antibiotics , and even whether we were delivered by c-section or not . diet , too , is emerging as one of the leading influences on the health of our guts . and while we ca n't control all these factors , we can manipulate the balance of our microbes by paying attention to what we eat . dietary fiber from foods like fruits , vegetables , nuts , legumes , and whole grains is the best fuel for gut bacteria . when bacteria digest fiber , they produce short chain fatty acids that nourish the gut barrier , improve immune function , and can help prevent inflammation , which reduces the risk of cancer . and the more fiber you ingest , the more fiber-digesting bacteria colonize your gut . in a recent study , scientists exchanged the regular high-fiber diets of a group of rural south africans with the high-fat , meat-heavy diets of a group of african-americans . after just two weeks on the high-fat , low-fiber , western-style diet , the rural african group showed increased inflammation of the colon , as well as a decrease of butyrate . that 's a short chain fatty acid thought to lower risk of colon cancer . meanwhile , the group that switched to a high-fiber , low-fat diet had the opposite result . so what goes wrong with our gut bacteria when we eat low-fiber processed foods ? lower fiber means less fuel for the gut bacteria , essentially starving them until they die off . this results in less diversity and hungry bacteria . in fact , some can even start to feed on the mucus lining . we also know that specific foods can affect gut bacteria . in one recent microbiome study , scientists found that fruits , vegetables , tea , coffee , red wine , and dark chocolate were correlated with increased bacterial diversity . these foods contain polyphenols , which are naturally occurring antioxidant compounds . on the other hand , foods high in dairy fat , like whole milk , and sugar-sweetened sodas were correlated with decreased diversity . how food is prepared also matters . minimally processed , fresh foods generally have more fiber and provide better fuel . so lightly steamed , sautéed , or raw vegetables are typically more beneficial than fried dishes . there are also ways of preparing food that can actually introduce good bacteria , also known as probiotics , into your gut . fermented foods are teeming with helpful probiotic bacteria , like lactobacillus and bifidobacteria . originally used as a way of preserving foods before the invention of refrigeration , fermentation remains a traditional practice all over the world . foods like kimchi , sauerkraut , tempeh , and kombucha provide variety and vitality to our diets . yogurt is another fermented food that can introduce helpful bacteria into our guts . that does n't necessarily mean that all yogurt is good for us , though . brands with too much sugar and not enough bacteria may not actually help . these are just general guidelines . more research is needed before we fully understand exactly how any of these foods interact with our microbiomes . we see positive correlations , but the insides of our guts are difficult places to make direct observations . for instance , we do n't currently know whether these foods are directly responsible for the changes in diversity , or if something more complicated is happening . while we 're only beginning to explore the vast wilderness inside our guts , we already have a glimpse of how crucial our microbiomes are for digestive health . the great news is we have the power to fire up the bacteria in our bellies . fill up on fibers , fresh and fermented foods , and you can trust your gut to keep you going strong .

we do n't yet have the blueprint for exactly which good bacteria a robust gut needs , but we do know that it 's important for a healthy microbiome to have a variety of bacterial species . many factors affect our microbiomes , including our environment , medications like antibiotics , and even whether we were delivered by c-section or not . diet , too , is emerging as one of the leading influences on the health of our guts .

other than food , what lifestyle factors can affect our microbiomes ?

wars are a tragic part of our history and will almost certainly be a tragic part of our future . since the establishment of the united nations , wars of aggression have been outlawed and multilateral conventions refer to armed conflict instead of war . but the wars of the future wo n't be like the wars of our past . alongside traditional warfare , our future will include cyberwarfare , remotely fighting our enemies through the use of a new class of weapons , including computer viruses and programs to alter the enemy 's ability to operate . and not only is cyberwarfare not covered by existing legal frameworks , but the question of what exactly constitutes cyberwarfare is still highly debated . so , how can we deal with cyberwarfare if we ca n't even agree on what it means ? one way forward is to envision situations where new international laws may be needed . imagine a new kind of assassin , one that could perpetrate a crime without firing a single shot or even being in the same country . for example , an individual working for the government uses a wireless device to send a signal to another foreign leader 's pacemaker . this device directs the pacemaker to malfunction , ultimately resulting in the foreign leader 's death . would this cyber assassination constitute an act of war ? as a second example , imagine an allied group of nations cooperatively infiltrating the computer systems of an enemy nation 's nuclear warship . this attack results in a nuclear-powered aircraft carrier almost melting down , which was stopped just short of killing thousands of soldiers and civilians . as a defensive measure , the enemy country responds by unleashing a defensive cyberattack that results in the allied nations ' power grids going down . hospitals can no longer treat patients , entire regions without heat or clean water , all ultimately causing tens of thousands civilian deaths . the origin of the power failure was the counterattack , but the fragile infrastructure , feeble cybersecurity , and the antiquated state of the power grid all contributed to the deaths of the civilians . could the country fight back ? who would they fight ? and would their retaliation be considered an act of war ? do they constitute war crimes against humanity ? who is to be held responsible ? the computer programmers who wrote the code ? the military project manager who oversaw the creation of the code ? the commander who hit the button , setting off the event ? the hardware engineer who created the computers , knowing that they were intended to enable an attack ? because war has been with us for so long , we have laws to deal with figuring out who should be held accountable for their actions in combat . these legal frameworks aim to contain and prevent atrocities from being more atrocious . commandeering civilian planes and using them as weapons , dropping atomic bombs , the use of gas chambers or poisonous gas in conflict , all of these actions , if committed , constitute acts of war and war crimes under customary international law and the hague conventions . again , the current legal framework stays silent on hypothetical questions and countless others because there are no easy answers , and there are only two ways to make progress on these questions : peace or new laws . so , what hypothetical but plausible scenarios can you imagine falling under the burgeoning definition of cyberwarfare , and how might you design an international legal framework to deter these activities ?

alongside traditional warfare , our future will include cyberwarfare , remotely fighting our enemies through the use of a new class of weapons , including computer viruses and programs to alter the enemy 's ability to operate . and not only is cyberwarfare not covered by existing legal frameworks , but the question of what exactly constitutes cyberwarfare is still highly debated . so , how can we deal with cyberwarfare if we ca n't even agree on what it means ? one way forward is to envision situations where new international laws may be needed .

what is the definition of cyberwarfare ?

translator : tom carter reviewer : bedirhan cinar every minute of every day , you breathe without even thinking about it . your body does it on its own , from the day you 're born until the day you die . you have muscles contract to bring oxygen , a gas , into your lungs , which is then transferred by your bloodstream to every cell in your body . gases are strange . we ca n't see them , but we know they 're there because we can feel them . what we experience as wind is really trillions and trillions of gas molecules slamming into your body . and it feels good , right ? science is based on observation . unfortunately , we can not observe gases with our eyes -- they 're too small . we have to use our other senses to make observations and draw conclusions . observations are then compiled , and we create a model . no , not that kind of model . a model is a way scientists describe the properties of physical phenomena . first , gases always move in a straight line . we do n't really have anything to demonstrate this with because gravity always pulls objects down . so imagine a bullet fired from a gun , and that bullet goes on at a constant speed in a perfectly straight line . that would be like a gas molecule . second , gases are so small , they occupy no volume on their own . as a group they do , blow up any balloon and you can see how that volume changes . but single gases have no volume compared to other forms of matter . rather than calculating such a small amount of matter , we just call it zero for simplicity . third , if gas molecules collide , and they do -- remember , these are assumptions -- their energy remains constant . an easy way to demonstrate this is by dropping a soccer ball with a tennis ball balanced on top . because the soccer ball is bigger , it has more potential energy , and the energy from the larger ball is transferred to the smaller tennis ball and it flies away when that energy is transferred . the total energy stays the same . gases work the same way . if they collide , smaller particles will speed up , larger particles will slow down . the total energy is constant . fourth , gases do not attract one another , and they do n't like to touch . but remember rule three . in reality , they do collide . finally , gases have energy that is proportional to the temperature . the higher the temperature , the higher the energy the gases have . the crazy thing is that at the same temperature , all gases have the same energy . it does n't depend on the type of gas , just the temperature that gas is at . keep in mind this is a model for the way gas particles behave , and based on our observations , gases always move in straight lines . they 're so small , that they 're not measurable on their own , and they do n't interact with one another . but if they do bump into one another , that energy is transferred from one particle to another , and the total amount never changes . temperature has a major effect , and in fact , all gases at the same temperature have the same average energy . whew ! i need to go catch my breath .

in reality , they do collide . finally , gases have energy that is proportional to the temperature . the higher the temperature , the higher the energy the gases have .

if you were given oxygen ( molecular mass = 18 amu ) and hydrogen ( molecular mass = 1 amu ) at the same temperature and pressure , which has more energy ? which gas would be moving faster ? why ? how is this different than energy ?

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 .

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 .

what principle can we use to explain why businesses cluster in groups instead of spreading evenly throughout a community ?

it can strike without warning , at any moment . you may be walking across a soft carpet and reaching for the door knob when suddenly ... zap ! to understand static electricity , we first need to know a bit about the nature of matter . all matter is made up of atoms that consist of three types of smaller particles : negatively charged electrons , positively charged protons , and neutral neutrons . normally , the electrons and protons in an atom balance out , which is why most matter you come across is electrically neutral . but electrons are tiny and almost insignificant in mass , and rubbing or friction can give loosely bound electrons enough energy to leave their atoms and attach to others , migrating between different surfaces . when this happens , the first object is left with more protons than electrons and becomes positively charged , while the one with more electrons accumulates a negative charge . this situation is called a charge imbalance , or net charge separation . but nature tends towards balance , so when one of these newly charged bodies comes into contact with another material , the mobile electrons will take the first chance they get to go where they 're most needed , either jumping off the negatively charged object , or jumping onto the positively charged one in an attempt to restore the neutral charge equilibrium . and this quick movement of electrons , called static discharge , is what we recognize as that sudden spark . this process does n't happen with just any objects . otherwise you 'd be getting zapped all the time . conductors like metals and salt water tend to have loosely bound outer electrons , which can easily flow between molecules . on the other hand , insulators like plastics , rubber and glass have tightly bound electrons that wo n't readily jump to other atoms . static build-up is most likely to occur when one of the materials involved is an insulator . when you walk across a rug , electrons from your body will rub off onto it , while the rug 's insulating wool will resist losing its own electrons . although your body and the rug together are still electrically neutral , there is now a charge polarization between the two . and when you reach to touch the door knob , zap ! the metal door knob 's loosely bound electrons hop to your hand to replace the electrons your body has lost . when it happens in your bedroom , it 's a minor nuisance . but in the great outdoors , static electricity can be a terrifying , destructive force of nature . in certain conditions , charge separation will occur in clouds . we do n't know exactly how this happens . it may have to do with the circulation of water droplets and ice particles within them . regardless , the charge imbalance is neutralized by being released towards another body , such as a building , the earth , or another cloud in a giant spark that we know as lightning . and just as your fingers can be zapped over and over in the same spot , you better believe that lightning can strike the same place more than once .

when it happens in your bedroom , it 's a minor nuisance . but in the great outdoors , static electricity can be a terrifying , destructive force of nature . in certain conditions , charge separation will occur in clouds .

which of the following will usually create static electricity ?

today lots of girls play sports . but , for a long time , girls were not encouraged to kick , throw , run , jump , shoot , slide , or hit like boys . so , why did things change ? and how much have they changed ? are girls and boys treated equally when it comes to sports ? to begin to answer these questions , we have to look back . in 1972 , congress passed a law called title ix , which protected girls and women from discrimination in schools , colleges , and universities . this included discrimination in school-sponsored sports . at that time , only 15 % of college athletes were women , and in high schools , only 7 % of athletes were girls . female athletes did n't get a lot of support either and often had to provide their own uniforms and equipment . it was title ix that forced school administrators to make sports more equal . but what does equal mean in sports ? the government developed rules to measure equality under two general categories : participation and treatment . in the early days of title ix , the number of girls playing sports was so low that it would have been very difficult for schools to suddenly provide exactly the same number of opportunities for girls and boys . instead , the government wrote rules that gave schools three options , or tests , to demonstrate fairness in opportunities for girls . the three tests are proportionality , progress , and satisfied interests . a school can pick which test to follow . proportionality means that girls should receive the same percentage of athletic opportunities as the percentage of girls in the student body . so , if 51 % of students are girls , then girls should have approximately 51 % of the opportunities to play sports . the second test , progress , requires schools to make up for the days when girls had fewer opportunities by adding new sports for girls on a regular basis . the third test asks if girls interested in athletics are satisfied . under this test , a school must regularly ask female students what sports they are interested in and also take into consideration the popularity of certain sports in the area where the school is located . it must , then , add teams according to the girls ' interests . another important part of title ix is that it does n't just look at how many athletic opportunities are available to each sex but whether those opportunities are of equal quality . specifically , title ix requires equality between boys and girls teams for things like equipment and supplies , publicity , the scheduling of games and practice times , and the quality and number of coaches . girls should also have equal access to locker rooms , practice spaces , and competitive facilities , as well as medical services . so , if the best time to play basketball is on friday nights because that 's when most parents and fans can come , then the girls and boys teams should take turns playing on friday night . if boys teams play in a stadium with lights , scoreboards , and concession stands , then girls teams must have the same opportunity , either by sharing those facilities or getting their own of equal quality . but , as we all know , just because a law exists does n't mean that everybody follows it . school officials are responsible for making sure there is fairness in sports , but you can help , too , by keeping an eye on your own school . look around . are there a lot more boys than girls who play sports ? is the boys ' soccer field better than the girls ' ? are athletic trainers available to all teams equally ? does the baseball team get new uniforms every year , while the softball team gets them every three years ? if you think there might be inequality in your schools , you can approach a school administrator , a parent , or the office of civil rights , a government agency that makes sure schools comply with title ix because equality is important for everyone , both on the field and off .

are there a lot more boys than girls who play sports ? is the boys ' soccer field better than the girls ' ? are athletic trainers available to all teams equally ?

jefferson high school decides to add a girls ’ softball team in order to demonstrate progress towards equality . yet , because there is already a football field , a baseball field , and a soccer field on high school property , there is not room to add a softball field . so jhs makes arrangements with the city for the softball team to play on a municipal field that is used by local amateur leagues . the field is two miles away from school . there is no locker room for the girls to use , and the field does not have lights or a concession stand . maintenance such as mowing and lining of the field does not occur on a regular basis . in comparison , all of the facilities at jefferson high school have locker rooms available and are well maintained . the football stadium has a concession stand and the baseball field has lights . if you were a member of the jhs softball team , would you think this is fair ? what would you do about it ?

if i were to distill the 20 years of elephant research that i 've done into one sentence , what would it be ? what could i tell you ? i would say that elephants are just like us ! and what do i mean by that ? it takes a lot of patience to be out there in the field and trying to figure out patterns of these very slow and intelligent animals . but over time , it is true they are very similar to us . and you think , `` well , how can i say that ? look , they have huge ears , they have really long noses . what do you mean they 're like us ? '' well , in fact , their families are very similar to ours . and family is extremely important to elephants . they grow up in very tight-knit families and they have extended families . and it 's just like our family reunions where you have all the aunts gathering around with all the food they 're going to bring and plan , and all the boys are thinking , `` are we going to play our video games together ? are we going to spar ? '' it 's very , very similar , and it 's jubilant , and screaming , yelling , it 's really amazing to see . but , as soon as you get that family gathering , it 's just like a wedding or anything else , all of the sudden the family politics come out , and the lower-ranking individuals in this scene , you see the arrow off to the back , the lower-ranking individuals already know their station , they 're going to drink at the muddiest part of the pan because the whole family 's here and we ca n't drink at the best water because that 's reserved for the top-ranking family . what 's also very similar is that you have elders in the group that everyone reveres . this is the matriarch , and the other female is reaching over and doing what 's called a trunk to mouth placing her trunk in the mouth , and it 's a sign of respect , it 's kind of like a handshake , but it 's also like a salute . and this salute is learned at a very young age . now , ritual and bonding within the family also facilitates coordinated activities . so , here 's a young female whose calf has fallen into the trough and she does n't know what to do and she panics . well , the older female , that 's the matriarch , she says , `` no problem here , '' she just scoops the baby out . now , that 's not true for a lot of different families , they ca n't coordinate very well , the younger females do n't really know what to do , but the older ones will just get down , kneel down together and pick the baby out . another thing that 's very similar is the coming of age of teenage boys . male elephants at the age of about 12 to 15 . the biggest elephant in this photograph here is an elephant who 's about the leave the family . he gets too big , he gets a little fresh , the adult females had enough of him , but he also is independent , he wants to go out and play with the guys . so what happens then is that you have this all male society , very ritual male society . greg is our main dominant bull here , you can see him in the middle . he 's got a huge posse , his following reveres him . and it 's very interesting how very good leaders , very good dominant individuals know how to titrate the carrot and the stick . this guy 's a master at it , and there 's other bullies out there that want to kind of want to create their own little following , but they ca n't do it because they 're too agressive . and so when he 's not around they try and sweet talk the underlings to come into their fold , and they actually become less agressive . so it 's very interesting to see how politics play out in these male and female societies . now back to the ladies here . in a core family group you 'll have a mother , maybe even a grandmother , her daughters and all of their offspring , the male and female calves . and what 's very interesting here is that how character makes a difference . so each matriarch has a very different character . these two characters are kind of curious , they 're uncertain , whereas these other two characters are really agressive . `` we 're going to charge first , ask questions later . '' but then there are also matriarchs that say , `` forget it ! i 'm going to run first and then figure it out when we 're in the bush and it 's safe . '' but the wisest matriarch , the matriarchs that succeed best in all of the studies that have been done , is the one that assesses the danger and decides is this worth running away from or is this not a big deal at all . now being social is super important for elephants and of course right at the beginning , just like early childhood development , socialization is very important . bathing together , eating together , playing together , rough housing , this is all very important for social development . and who has n't tried to beat their sibling to the head of the line coming into the water hole ? and these relationships from the beginning is just like best friends forever for real . these females are going to live together for life . now if it 's a male , female they might know each other for life , but it 's really important to develop those bonds early on . those are the relationships that are going to save you later . i 'll show you a little schoolyard scenario here . where , i think if you just focus on what 's happening here you can see that we have the bully , he 's pulling on the trunk of this baby calf , and then we have the diplomat who 's reaching over and saying , `` no , do n't do that ! stop doing that ! '' and then , of course , we have the bystander . and how do you get these three different characters within the family ? it 's kind of fascinating to think that elephants really are just like us . and so i got curious about this and i thought , `` well , what if you measure the difference in character of a dominant female 's calf versus a lower-ranking female 's calf , and see what happens in their growing up . '' and so we started doing this . and you can see this little guy with his ears out , really charging at you . the difference between that character and the character who holds back , wants to touch mom , is n't so certain about what 's going on here . but the other one 's charging ahead all confident . well , we started measuring how far away a calf will stray from mom , how often do they touch others , how often do they initiate play , and then look at the dominance of the females , of their mothers . and what we found is that socializing with the dominant calves actually socialize more significantly more than the lower-ranking calves . and what it looks like is it 's not that the lower-ranking calves do n't want to play , they 're actually not allowed to interact with the higher-ranking calves . they get swatted away from the dominant females . and so this is kind of the downside of , okay we are very much like elephants , elephants are as much like us , but it 's kind of for better or for worse because i can also see this happening in humans and maybe we should take a lesson from that . one last thing that we found is that the males will be the risk-takers , they 're more independent and they 're more likely to spend more time away from mom . and that 's very true in human societies and with other social animals . so i hope i 've convinced you that we have very similar lives to elephants and that elephants have very individual , durable characters that we 've measured across years . the bully always tends to be the bully unless there 's some kind of social upset , and he decides he better be a softy or else he 's not going to gain favor at all . and then you have the gentle giants that are always going to be gentle . the young males really need mentoring from the elders , and those gentle giants are very good at doing that , soliciting them . leaving family is a really hard things for the males , but they survive and they figure out who to hang out with . so , just to end here , i just wanted to say that since they are so similar to us , and have these characters , i hope when you see them on tv or you go out and you 're lucky enough to see them in the wild , that maybe you 'll think of them as individual characters deserving of our attention , and also deserving of our protection . thank you .

well , we started measuring how far away a calf will stray from mom , how often do they touch others , how often do they initiate play , and then look at the dominance of the females , of their mothers . and what we found is that socializing with the dominant calves actually socialize more significantly more than the lower-ranking calves . and what it looks like is it 's not that the lower-ranking calves do n't want to play , they 're actually not allowed to interact with the higher-ranking calves . they get swatted away from the dominant females .

a low ranking mother ’ s status in the family ____ transferred onto her calves .

using the word shakespeare within any classroom in the 21st century has become almost as dangerous for teachers as putting balloons in a toaster . after uttering this simple word , the common teacher is met with a mass of groans , moans , devastated looks , and the occasional chair tossed in his or her direction . but shakespearean works are not boring , confusing , long and painful plays written more than 400 years ago . they 're adventures relating to the extremities of human nature : love , hate , jealousy , zealous ambition , fear , mistrust , deception , and murder . we owe much of our own language to his invention . he invented over 2,000 words for use in his plays , which still remain in the oxford english dictionary . words like `` countless '' and `` assassination '' as well as phrases like `` one fell swoop , '' `` foul play , '' and even `` to be in a pickle '' all originated from william 's brilliant brain . and there are many echoes of shakespeare 's romantic language too . if you read < em > romeo and juliet < /em > , you 'll come across sentences like , `` she doth teach the torches to burn bright , '' and , `` so shows a snowy dove trooping with crows . '' both are quite clever metaphors , suggesting that juliet is both exceptionally beautiful and far moreso than anyone else . `` for thou art as glorious to this night , being o'er my head , as is a winged messenger of heaven , '' is a simile suggesting angelic qualities of the lady in question . this is not too different from today 's comments like , `` hey , beautiful ! '' and , `` you 're the hottest girl in the room . '' shakespeare also uses slightly more complex metaphors to describe the intentions of a mischievous man . for instance , `` this holy shrine , the gentle sin is this : my lips , two blushing pilgrims , ready stand to smooth that rough touch with a tender kiss , '' essentially means , `` i wish to kiss you . '' such male intentions were not limited to simple pecks on the cheek either . an intentional ambiguity was often used as a cheeky means to proposition marriage or a more intimate relationship . therefore , instead of viewing shakespearean works as out-dated , boring , and unhelpful , start reading today and discover the best ways to get the one you love to love you back .

words like `` countless '' and `` assassination '' as well as phrases like `` one fell swoop , '' `` foul play , '' and even `` to be in a pickle '' all originated from william 's brilliant brain . and there are many echoes of shakespeare 's romantic language too . if you read < em > romeo and juliet < /em > , you 'll come across sentences like , `` she doth teach the torches to burn bright , '' and , `` so shows a snowy dove trooping with crows . ''

which three poetic devices are used in the shakespeare animation ?

[ 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 ]

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 .

`` the water 's one thing . but you take a step back and you look at what 's going on in the community , it 's heartbreaking , '' said the football coach in the film . explain what he means by this statement . why might it be heartbreaking for him ?

on august 21 , 2017 the shadow of the moon will pass from the west coast to the east coast of the u.s. our blue sky will turn black as night and fill with stars , and there will be a hole in the sky where the sun used to be , surrounded by the fiery ring of the sun 's corona , a total eclipse of the sun . this will truly be a historic event . accounts of solar eclipses date way back on the written record . the early mesopotamians wrote that the sun was put to shame during the solar eclipse of the 14th century b.c.e . and it may have started the sun worship of the egyptian pharaoh akhenaten . ancient chinese astrologers paid with their lives if they failed to predict the solar eclipse and portend the fate of their emperors whose symbol was the sun . the earliest date of a specific event in human history , a battle between the armies of lydia and media , occurred on may 28 , 535 b.c.e . when a solar eclipse caused the soldiers to lay down their arms and declare a truce . so how does it happen ? during a total solar eclipse , the moon moves between the earth and the sun . when this happens , the disc of the moon appears to perfectly cover the disc of the sun even though the sun is much larger than the moon . but how is this possible ? the sun is 400 times bigger than the moon , but by sheer coincidence , the moon is 390 times closer to earth . size and distance cancel each other out so that the moon and sun appear to be almost the exactly same size . every time the moon orbits the earth , once every 27.3 days , it has to pass between the earth and the sun , a stage called the new moon phase . and every time it passes , the new moon has a chance to block out the sun . most of the time , the moon passes a little above or a little below the sun , but if they align perfectly , the shadow of the moon will make a narrow path across earth and those in the shadows will see a total solar eclipse . just like on night side of the earth , the sky during a total eclipse is black and filled with stars . but while the moon perfectly covers the surface of the sun , it does n't block out the sun 's outer atmosphere , its corona , which appears as a fiery ring around the dark disc of the moon . solar eclipses occur several times a year , but most often they are partial eclipses where the moon does n't quite line up with the sun . and , when the moon and sun are perfectly aligned , the moon is usually too far from earth in its orbit to completely cover the sun , creating an annular eclipse . during an annular or partial eclipse , the sky remains bright . even on those rare occasions of a total eclipse , the moon 's shadow is most likely to fall on the 70 % of earth that is covered by water , and few people , if any , will see it . the eclipse of 2017 will be remarkable on a larger scale because the moon is slowly moving away from earth . if a furry ancestor of ours had bothered to look up during a solar eclipse a hundred million years ago , it would n't have seen the fiery corona of the sun . it would have just been dark . eventually , the moon will have moved too far from earth to completely cover the disc of the sun . it is only during our little wink of earth 's history that the moon is at just the right distance to cause a total solar eclipse yet not block the sun 's corona . so on august 21 , 2017 , when the moon exactly lines up with the sun and the moon is close enough to the earth , its shadow will cross the u.s. and , if you happen to be in its narrow path , you will witness one of the most awe-inspiring sights in the universe . but , as incredible as this event will be , total eclipses are one of the most dangerous as well . only specially tinted filters , specifically designed to observe the sun , should be used . the eclipse might put the sun to shame , but even a shamed sun can seriously damage your eyes .

solar eclipses occur several times a year , but most often they are partial eclipses where the moon does n't quite line up with the sun . and , when the moon and sun are perfectly aligned , the moon is usually too far from earth in its orbit to completely cover the sun , creating an annular eclipse . during an annular or partial eclipse , the sky remains bright .

what type of eclipse occurs when the moon aligns with the sun but is too far from earth to block the sun completely ?

translator : ido dekkers reviewer : emma gon ( music ) every movie you 've ever seen , every tv show , every magazine , every time you surf the internet , you 're absorbing information , a bit like a sponge absorbs water . the words on the screen , the images , the colors , the sounds , the angle of the camera , every detail is designed to make you think , act or feel a certain way . your brain is subconsciously decoding images and sounds , and just by being alive today , by interacting with and reading all these different types of media , you 're already an expert at decoding and understanding these hidden messages . a set of codes and conventions that work together to make you feel happy , angry , afraid , excited . to make you want to buy a particular product -- a refreshing drink , a new phone . to style your hair a certain way . to cheer for the hero or boo the villain . welcome to the family tree of technical codes . so what constitutes a code ? first of all , it has to be recognized by all who read it . imagine a busy city where motorists do n't know how to read the traffic signals . we all have to know red equals stop , green means go , for the system to work . otherwise it would be chaos . secondly , codes are made meaningful by their context . we ca n't fully interpret or decipher a code until we see how it relates to other signs and symbols . look at these two intersecting lines . without any context , things around the code to help you understand or make meaning from it , it 's hard to know exactly what these lines represent . they could be a cross , symbolizing religion , an add sign , symbolizing a mathematical concept , the letter t from the alphabet , or they could just be two lines intersecting . if we add a crescent moon shape , and a circle with a line on it in front , the two lines now have a context , a relationship to their surroundings , and are magically revealed as the letter t. by adding additional information around the code , we 've changed its context , and therefore given it a concrete meaning . let 's meet the family . technical codes , senior has three sons : symbolic codes , written codes and technical codes , junior . symbolic codes has three sons : symbolic color , symbolic objects and symbolic animals . this branch of the family is all about representation . red represents hot or stop or danger , depending on its context . so if you see a red light above a yellow and a green light on a pole above the road , you know by this context that the light represents stop . written codes has three sons : you and only you , buzzwords and catchphrase . these guys are all about saying a lot with a little , or planting a word in your subconscious that triggers a response whenever you hear or read it . have you noticed how many times i 've said the word `` you ? '' you should feel like it 's directed specifically at you , and only you , that it 's addressing your needs and desire to learn about your world . if i tell you that all the cool , fresh and hip people are buying a new drink or wearing a particular brand , the buzzwords `` new , '' `` fresh '' or `` free '' make the product seem more interesting and appealing . if i wrap that product or idea in a simple phrase that 's easy to remember and becomes part of your everyday speech , then every time you hear or say those few words , your brain connects them to the product . so just do it , think different , and enjoy the power of the catchphrase . and technical codes , junior has three sons : camera angles , framing and lighting . for these boys , it 's all about how the camera is placed , how objects , people and places are shot , and what we see on screen -- or just as importantly , what we do n't see . when the camera is placed high above the subject , it makes you look small , insignificant and powerless . and the reverse is also true , when the camera is below . so is this video trying to manipulate you to buy something ? yes , an idea . the idea that understanding the relationship between technical codes and the role they play in shaping your understanding of the world around us through the media we consume is fun and interesting . is it trying to make you feel a certain way ? absolutely . every image , every word , has been carefully crafted to work together to make you feel positive about the idea that you need to be educated to engage with what you read , watch and listen to in movies , tv shows , magazines and on the internet . by understanding these codes , and how they work together to subconsciously change the way you think , feel and act towards products and ideas , you 'll be aware of these techniques and able to identify their impact on you . one of the most powerful advertising mediums in the world is word of mouth . if you 've ever recommended a product or movie , a service , or even a video online , then you 've played your part in passing the message . so soak all this information up . recognize how the family tree of technical codes works on you , and those around you , to make an impact find excellent examples , and spread the word .

if i wrap that product or idea in a simple phrase that 's easy to remember and becomes part of your everyday speech , then every time you hear or say those few words , your brain connects them to the product . so just do it , think different , and enjoy the power of the catchphrase . and technical codes , junior has three sons : camera angles , framing and lighting .

what are ways you have noticed different types of media shaping the way you think about the world ? do you think this is positive or negative ?

welcome to the ted-ed beta website tour . i 'm logan smalley , i 'm bedirhan cinar , i 'm jordan reeves , and i 'm stephanie lo . we represent the ted-ed team . we 're going to tell you about how the website is organized , about the lessons that surround each video , how you can customize or flip your own lesson , and how you can measure the lesson 's effect on your class or the world . towards the end of the tour , we 'll reveal one more major feature that directly affects every person viewing this video . let 's get started with the home page . on the home page , you 'll find original ted-ed videos , each is a lesson recorded by an actual educator that 's visualized by a professional animator . you can nominate educators and animators in the `` get involved '' section of the site . the ted-ed library can be browsed through two different lenses . learners can use the `` series '' view to browse videos thematically and based on their own curiosity . and teachers can use the browse by `` subject '' view to find the perfect short video to show in class or to assign as homework . every video on ted-ed is accompanied by a lesson . these lessons do n't replace good teaching , but they can be supplementary resources for students and teachers around the world . let 's look at this one , created by a teacher in the us and an animator in the uk . when you arrive on the lesson page , simply click play ; the video will continue to play as you navigate the lesson 's sections that surround it . in the `` quick quiz '' section , you 'll find multiple-choice questions that check for basic comprehension of the video . you get real-time feedback on your answers and if you get one wrong , you can use the video hint . you 'll find open-answer questions in the `` think '' section . and in the `` dig deeper '' section , you 'll find additional resources for exploring the topic . you can complete the lessons anonymously , but if you log in , you can track your own learning across the site . just visit the `` recent activity '' feed , and you 'll find answers you 've saved to lessons that you 've already started or completed . and now to one of the most powerful features of the ted-ed website : flipping a lesson . flipping a featured lesson allows you to edit each of the lesson 's sections . you can edit the title as it relates to your class . you can use the `` let 's begin '' section to provide instructions or context for the lesson . you can select or deselect any `` quick quiz '' question . in the `` think '' section , you can add your own open-answer questions . and in the `` dig deeper '' section , you can use the resources provided or add your own . when you finish flipping a lesson , it 'll publish to a new and unique url . and because the link is unique , it can measure the progress of any learner you share it with . you can use it to measure participation and accuracy of any individual student 's answers . so that 's how you flip a featured ted-ed video , we 've got one more major feature to tell you about . using the ted-ed platform , you can flip any video from youtube . that means you can create a lesson around any ted talk , any tedx talk , but also any of the other thousands of great educational videos on youtube , including the ones that you yourself could record , upload and flip . and through flipping these lessons , together we 'll create a free and remarkable library of lessons worth sharing .

so that 's how you flip a featured ted-ed video , we 've got one more major feature to tell you about . using the ted-ed platform , you can flip any video from youtube . that means you can create a lesson around any ted talk , any tedx talk , but also any of the other thousands of great educational videos on youtube , including the ones that you yourself could record , upload and flip .

what type of videos can you flip into a lesson using the ted-ed website ?

if you line up the entire text of `` moby dick , '' which was published in 1851 , into a giant rectangle , you may notice some peculiar patterns , like these words , which seem to predict the assassination of martin luther king , or these references to the 1997 death of princess di . so , was herman melville a secret prophet ? the answer is no , and we know that thanks to a mathematical principle called ramsey theory . it 's the reason we can find geometric shapes in the night sky , it 's why we can know without checking that at least two people in london have exactly the same number of hairs on their head , and it explains why patterns can be found in just about any text , even vanilla ice lyrics . so what is ramsey theory ? simply put , it states that given enough elements in a set or structure , some particular interesting pattern among them is guaranteed to emerge . as a simple example , let 's look at what 's called the party problem , a classic illustration of ramsey theory . suppose there are at least six people at a party . amazingly enough , we can say for sure that some group of three of them either all know each other , or have never met before , without knowing a single thing about them . we can demonstrate that by graphing out all the possibilities . each point represents a person , and a line indicates that the pair know each other . every pair only has two possibilities : they either know each other or they do n't . there are a lot of possibilities , but every single one has the property that we 're looking for . six is the lowest number of guests where that 's guaranteed to be the case , which we can express like this . ramsey theory gives us a guarantee that such a minimum number exists for certain patterns , but no easy way to find it . in this case , as the total number of guests grows higher , the combinations get out of control . for instance , say you 're trying to find out the minimum size of a party where there 's a group of five people who all know each other or all do n't . despite five being a small number , the answer is virtually impossible to discover through an exhaustive search like this . that 's because of the sheer volume of possibilities . a party with 48 guests has 2^ ( 1128 ) possible configurations , more than the number of atoms in the universe . even with the help of computers , the best we know is that the answer to this question is somewhere between 43 and 49 guests . what this shows us is that specific patterns with seemingly astronomical odds can emerge from a relatively small set . and with a very large set , the possibilities are almost endless . any four stars where no three lie in a straight line will form some quadrilateral shape . expand that to the thousands of stars we can see in the sky , and it 's no surprise that we can find all sorts of familiar shapes , and even creatures if we look for them . so what are the chances of a text concealing a prophecy ? well , when you factor in the number of letters , the variety of possible related words , and all their abbreviations and alternate spellings , they 're pretty high . you can try it yourself . just pick a favorite text , arrange the letters in a grid , and see what you can find . the mathematician t.s . motzkin once remarked that , `` while disorder is more probable in general , complete disorder is impossible . '' the sheer size of the universe guarantees that some of its random elements will fall into specific arrangements , and because we evolved to notice patterns and pick out signals among the noise , we are often tempted to find intentional meaning where there may not be any . so while we may be awed by hidden messages in everything from books , to pieces of toast , to the night sky , their real origin is usually our own minds .

just pick a favorite text , arrange the letters in a grid , and see what you can find . the mathematician t.s . motzkin once remarked that , `` while disorder is more probable in general , complete disorder is impossible . ''

the mathematician t.s . mazkin stated that :

i 'll begin today by sharing a poem written by my friend from malawi , eileen piri . eileen is only 13 years old , but when we were going through the collection of poetry that we wrote , i found her poem so interesting , so motivating . so i 'll read it to you . she entitled her poem `` i 'll marry when i want . '' ( laughter ) `` i 'll marry when i want . my mother ca n't force me to marry . my father can not force me to marry . my uncle , my aunt , my brother or sister , can not force me to marry . no one in the world can force me to marry . i 'll marry when i want . even if you beat me , even if you chase me away , even if you do anything bad to me , i 'll marry when i want . i 'll marry when i want , but not before i am well educated , and not before i am all grown up . i 'll marry when i want . '' this poem might seem odd , written by a 13-year-old girl , but where i and eileen come from , this poem , which i have just read to you , is a warrior 's cry . i am from malawi . malawi is one of the poorest countries , very poor , where gender equality is questionable . growing up in that country , i could n't make my own choices in life . i could n't even explore personal opportunities in life . i will tell you a story of two different girls , two beautiful girls . these girls grew up under the same roof . they were eating the same food . sometimes , they would share clothes , and even shoes . but their lives ended up differently , in two different paths . the other girl is my little sister . my little sister was only 11 years old when she got pregnant . it 's a hurtful thing . not only did it hurt her , even me . i was going through a hard time as well . as it is in my culture , once you reach puberty stage , you are supposed to go to initiation camps . in these initiation camps , you are taught how to sexually please a man . there is this special day , which they call `` very special day '' where a man who is hired by the community comes to the camp and sleeps with the little girls . imagine the trauma that these young girls go through every day . most girls end up pregnant . they even contract hiv and aids and other sexually transmitted diseases . for my little sister , she ended up being pregnant . today , she 's only 16 years old and she has three children . her first marriage did not survive , nor did her second marriage . on the other side , there is this girl . she 's amazing . ( laughter ) ( applause ) i call her amazing because she is . she 's very fabulous . that girl is me . ( laughter ) when i was 13 years old , i was told , you are grown up , you have now reached of age , you 're supposed to go to the initiation camp . i was like , `` what ? i 'm not going to go to the initiation camps . '' you know what the women said to me ? `` you are a stupid girl . stubborn . you do not respect the traditions of our society , of our community . '' i said no because i knew where i was going . i knew what i wanted in life . i had a lot of dreams as a young girl . i wanted to get well educated , to find a decent job in the future . i was imagining myself as a lawyer , seated on that big chair . those were the imaginations that were going through my mind every day . and i knew that one day , i would contribute something , a little something to my community . but every day after refusing , women would tell me , `` look at you , you 're all grown up . your little sister has a baby . what about you ? '' that was the music that i was hearing every day , and that is the music that girls hear every day when they do n't do something that the community needs them to do . when i compared the two stories between me and my sister , i said , `` why ca n't i do something ? why ca n't i change something that has happened for a long time in our community ? '' that was when i called other girls just like my sister , who have children , who have been in class but they have forgotten how to read and write . i said , `` come on , we can remind each other how to read and write again , how to hold the pen , how to read , to hold the book . '' it was a great time i had with them . nor did i just learn a little about them , but they were able to tell me their personal stories , what they were facing every day as young mothers . that was when i was like , 'why ca n't we take all these things that are happening to us and present them and tell our mothers , our traditional leaders , that these are the wrong things ? '' it was a scary thing to do , because these traditional leaders , they are already accustomed to the things that have been there for ages . a hard thing to change , but a good thing to try . so we tried . it was very hard , but we pushed . and i 'm here to say that in my community , it was the first community after girls pushed so hard to our traditional leader , and our leader stood up for us and said no girl has to be married before the age of 18 . ( applause ) in my community , that was the first time a community , they had to call the bylaws , the first bylaw that protected girls in our community . we did not stop there . we forged ahead . we were determined to fight for girls not just in my community , but even in other communities . when the child marriage bill was being presented in february , we were there at the parliament house . every day , when the members of parliament were entering , we were telling them , `` would you please support the bill ? '' and we do n't have much technology like here , but we have our small phones . so we said , `` why ca n't we get their numbers and text them ? '' so we did that . it was a good thing . ( applause ) so when the bill passed , we texted them back , `` thank you for supporting the bill . '' ( laughter ) and when the bill was signed by the president , making it into law , it was a plus . now , in malawi , 18 is the legal marriage age , from 15 to 18 . ( applause ) it 's a good thing to know that the bill passed , but let me tell you this : there are countries where 18 is the legal marriage age , but do n't we hear cries of women and girls every day ? every day , girls ' lives are being wasted away . this is high time for leaders to honor their commitment . in honoring this commitment , it means keeping girls ' issues at heart every time . we do n't have to be subjected as second , but they have to know that women , as we are in this room , we are not just women , we are not just girls , we are extraordinary . we can do more . and another thing for malawi , and not just malawi but other countries : the laws which are there , you know how a law is not a law until it is enforced ? the law which has just recently passed and the laws that in other countries have been there , they need to be publicized at the local level , at the community level , where girls ' issues are very striking . girls face issues , difficult issues , at the community level every day . so if these young girls know that there are laws that protect them , they will be able to stand up and defend themselves because they will know that there is a law that protects them . and another thing i would say is that girls ' voices and women 's voices are beautiful , they are there , but we can not do this alone . male advocates , they have to jump in , to step in and work together . it 's a collective work . what we need is what girls elsewhere need : good education , and above all , not to marry whilst 11 . and furthermore , i know that together , we can transform the legal , the cultural and political framework that denies girls of their rights . i am standing here today and declaring that we can end child marriage in a generation . this is the moment where a girl and a girl , and millions of girls worldwide , will be able to say , `` i will marry when i want . '' ( applause ) thank you . ( applause )

i was like , `` what ? i 'm not going to go to the initiation camps . '' you know what the women said to me ?

why did memory refuse to participate in the orientation camps ?

translator : tom carter reviewer : bedirhan cinar optics , or the enhancement of our natural vision , has been one of the biggest catalysts for science over the past 500 years , interestingly , it was n't scientific interest , but more practical matters that led to the initial advancements in optics , starting around 1440 when johannes gutenberg invented his printing press . in short order , books , which had been a rarity , were now becoming a widespread phenomenon . all that new reading material meant more knowledge was circulating , but it also meant that more people were straining their eyes , likely as they read by candlelight . and while spectacles had been invented in italy around 1286 , the need for reading glasses increased substantially . now that people could use lenses to see things more clearly , they started wondering if vision could be enhanced to see things the human eye could n't perceive by its own devices . robert hooke pursued microscopy , and 1665 he published his findings of worlds inside worlds , which he called `` cells '' in the book `` micrographia . '' at the other end of the spectrum , galileo innovated with telescopic lenses , and in 1609 , he had refined a telescope until he had an instrument powerful enough to see distant objects in the sky with an accuracy no one had before him . he found that the moon had craters and mountains , that jupiter had moons of its own , and the whole system governing the earth and space was brought into question . not everyone was thrilled with all the things galileo saw though . for instance , it was taught at the time that the moon was a perfectly smooth sphere . yet here was visual proof that was awfully hard to discount . upon finding moons around jupiter , he also verified what johannes kepler had surmised : that the earth was not the center of the universe , dispelling another central dogma of galileo 's day . then almost exactly a year after galileo died , isaac newton was born . a lot that had been unknown was visible by now , but much of it was simply the foundation for further questions . what was light anyway ? and color , for that matter ? what were the laws that governed the earth , and the heavens ? and could we capture them through keen observation ? newton experimented extensively with optics , and came to understand light as something of substance , and colors as components of light at different frequencies . before newton , people widely believed that the color was due to different amounts of light , with red being lots of light , and blue being mostly dark . newton 's prism experiments showed that white light could not only be broken into its component colors with one prism , but that a second lens could recompose those colors back into white light again , thus showing that color was a matter of light 's refraction rather than how light or dark it was . newton 's studies of optics led to the development of the reflecting telescope . this , together with his study of planetary motion , led to his theory of gravitation , one of the world 's greatest examples of learning to see something invisible by observing its effect on things that are visible . so fast forward a few hundred years , and here we stand . we 've evolved from a single lens to optics that reveal the birth of a star in another galaxy , or a child developing in the womb , or an electron whirling around an atom . at a time when so much is visible , how we see the world around us matters even more than what we see . will we see a world where everything important has already been discovered ? or will we see one in which yesterday 's discoveries are but a doorway to the breakthroughs of tomorrow ?

newton 's prism experiments showed that white light could not only be broken into its component colors with one prism , but that a second lens could recompose those colors back into white light again , thus showing that color was a matter of light 's refraction rather than how light or dark it was . newton 's studies of optics led to the development of the reflecting telescope . this , together with his study of planetary motion , led to his theory of gravitation , one of the world 's greatest examples of learning to see something invisible by observing its effect on things that are visible .

according to timothy , what is optics ?

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 .

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 .

in many stories , the hero must cross a physical barrier that separates the ordinary world from the special world , but the two worlds aren ’ t always physical places . can you think of a story that follows a hero ’ s journey through a “ special world ” of unfamiliar emotional territory ?

we live in a three-dimensional world where everything has length , width , and height . but what if our world were two-dimensional ? we would be squashed down to occupy a single plane of existence , geometrically speaking , of course . and what would that world look and feel like ? this is the premise of edwin abbott 's 1884 novella , flatland . flatland is a fun , mathematical thought experiment that follows the trials and tribulations of a square exposed to the third dimension . but what is a dimension , anyway ? for our purposes , a dimension is a direction , which we can picture as a line . for our direction to be a dimension , it has to be at right angles to all other dimensions . so , a one-dimensional space is just a line . a two-dimensional space is defined by two perpendicular lines , which describe a flat plane like a piece of paper . and a three-dimensional space adds a third perpendicular line , which gives us height and the world we 're familiar with . so , what about four dimensions ? and five ? and eleven ? where do we put these new perpendicular lines ? this is where flatland can help us . let 's look at our square protagonist 's world . flatland is populated by geometric shapes , ranging from isosceles trianges to equilateral triangles to squares , pentagons , hexagons , all the way up to circles . these shapes are all scurrying around a flat world , living their flat lives . they have a single eye on the front of their faces , and let 's see what the world looks like from their perspective . what they see is essentially one dimension , a line . but in abbott 's flatland , closer objects are brighter , and that 's how they see depth . so a triangle looks different from a square , looks different a circle , and so on . their brains can not comprehend the third dimension . in fact , they vehemently deny its existence because it 's simply not part of their world or experience . but all they need , as it turns out , is a little boost . one day a sphere shows up in flatland to visit our square hero . here 's what it looks like when the sphere passes through flatland from the square 's perspective , and this blows his little square mind . then the sphere lifts the square into the third dimension , the height direction where no flatlander has gone before and shows him his world . from up here , the square can see everything : the shapes of buildings , all the precious gems hidden in the earth , and even the insides of his friends , which is probably pretty awkward . once the hapless square comes to terms with the third dimension , he begs his host to help him visit the fourth and higher dimensions , but the sphere bristles at the mere suggestion of dimensions higher than three and exiles the square back to flatland . now , the sphere 's indignation is understandable . a fourth dimension is very difficult to reconcile with our experience of the world . short of being lifted into the fourth dimension by visiting hypercube , we ca n't experience it , but we can get close . you 'll recall that when the sphere first visited the second dimension , he looked like a series of circles that started as a point when he touched flatland , grew bigger until he was halfway through , and then shrank smaller again . we can think of this visit as a series of 2d cross-sections of a 3d object . well , we can do the same thing in the third dimension with a four-dimensional object . let 's say that a hypersphere is the 4d equivalent of a 3d sphere . when the 4d object passes through the third dimension , it 'll look something like this . let 's look at one more way of representing a four-dimensional object . let 's say we have a point , a zero-dimensional shape . now we extend it out one inch and we have a one-dimensional line segment . extend the whole line segment by an inch , and we get a 2d square . take the whole square and extend it out one inch , and we get a 3d cube . you can see where we 're going with this . take the whole cube and extend it out one inch , this time perpendicular to all three existing directions , and we get a 4d hypercube , also called a tesseract . for all we know , there could be four-dimensional lifeforms somewhere out there , occasionally poking their heads into our bustling 3d world and wondering what all the fuss is about . in fact , there could be whole other four-dimensional worlds beyond our detection , hidden from us forever by the nature of our perception . does n't that blow your little spherical mind ?

what they see is essentially one dimension , a line . but in abbott 's flatland , closer objects are brighter , and that 's how they see depth . so a triangle looks different from a square , looks different a circle , and so on .

how do shapes in flatland perceive depth ?

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

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

in which state does the “ zone of death ” belong ?

it 's so obvious that it 's practically proverbial . you ca n't unboil an egg . well , it turns out you can , sort of . what thermal energy does to the eggs ' molecules , mechanical energy can undo . eggs are mostly made of water and proteins . the proteins start off folded up into intricate shapes , held together by weak chemical bonds . adding heat disrupts those bonds , allowing the proteins to unfold , uncoil , unwind and wiggle freely . this process is called denaturing . the newly liberated proteins bump up against their neighbors and start to form new bonds with each other , more and more as the heat increases , until finally , they 're so entangled that they gel into a solid mass , a boiled egg . that entanglement might look permanent , but it 's not . according to a chemical idea called the principle of microscopic reversibility , anything that happens , like egg proteins seizing up , can theoretically unhappen if you retrace your steps . but adding more heat will tangle the proteins further , and cooling them down will only freeze them , so here 's the trick : spin them around ridiculously fast . i 'm not kidding . here 's how it works . first , scientists dissolve boiled egg whites in water with a chemical called urea , a small molecule that acts as a lubricant , coating the proteins ' long strands and making it easier for them to glide past each other . then , they spin that solution in a glass tube at a breakneck 5000 rotations per minute , making the solution spread out into a thin film . here 's the key part . the solution nearest the wall spins faster than the solution closer to the middle . that difference in velocity creates sheer stresses that repeatedly stretch and contract the proteins until eventually they snap back into their native shapes and stay there . by the time the centrifuge stops spinning , the egg white is back in its original unboiled state . this technique works with all sorts of proteins . bigger , messier proteins can be more resistant to being pulled apart , so scientists attach a plastic bead to one end that adds extra stress and encourages it to fold up first . this unboiling method wo n't work with a whole egg in its shell since the solution has to spread throughout a cylindrical chamber . but the applications go way beyond uncooking your breakfast , anyhow . many pharmaceuticals consist of proteins that are extremely expensive to produce , partly because they get stuck in tangled up aggregates , just like cooked egg whites and have to be untangled and refolded before they can do their jobs . this spinning technique has the potential to be an easier , cheaper and quicker method than other ways to refold proteins , so it may allow new drugs to be made available to more people faster . and there 's one more thing you need to keep in mind before trying to uncook all of your food . boiling an egg is actually an unusual cooking process because even though it changes the way proteins are shaped and bound together , it does n't actually change their chemical identity . most types of cooking are more like the famous maillard reaction , which makes chemical changes that turn sugars and proteins into delicious caramel crunchiness and are a lot harder to undo . so you might be able to unboil your egg , but i 'm sorry to say you ca n't unfry it ... yet .

here 's how it works . first , scientists dissolve boiled egg whites in water with a chemical called urea , a small molecule that acts as a lubricant , coating the proteins ' long strands and making it easier for them to glide past each other . then , they spin that solution in a glass tube at a breakneck 5000 rotations per minute , making the solution spread out into a thin film .

when the egg goes from raw to boiled , the egg whites ' proteins start _____ and end up _____ .

in 1796 , thomas jefferson received a box of bones he could n't identify . a long , sharp claw reminded him of a lion , but the arm bones suggested a larger animal , one about three meters long . thinking it might be huge unknown species of north american lion , jefferson warned explorers lewis and clark to keep an eye out for this mysterious predator . but jefferson 's box of bones did n't come from a lion . they came from an extinct giant sloth . prehistoric ground sloths first appeared around 35 million years ago . dozens of species lived across north , central and south america , alongside other ancient creatures like mastodons and giant armadillos . some ground sloths , like the megalonychid , were cat-sized , but many were massive . jefferson 's sloth , megalonyx , weighed about a ton , and that was small compared to megatherium , which could reach six metric tons , as much as an elephant . they ambled through the forests and savannas using their strong arms and sharp claws to uproot plants and climb trees , grazing on grasses , leaves , and prehistoric avocados . in fact , we might not have avocados today if not for the giant sloths . smaller animals could n't swallow the avocado 's huge seed , but the sloths could , and they spread avocado trees far and wide . ground sloths flourished for millions of years , but around 10,000 years ago , they started disappearing along with the western hemisphere 's other giant mammals . researchers think that ground sloths could have been pushed out by an oncoming ice age , or competition with other species , maybe humans , who arrived in the region around the time most of the sloths went extinct . some of the smaller sloths did survive and migrated to the treetops . today , there are six species left living in the rainforest canopies of central and south america . hanging out in the trees is a good way to avoid predators , and there are plenty of leaves to eat . but this diet has its drawbacks . animals extract energy from food and use that energy to move around , maintain their body temperature , keep their organs working , and all the other activities necessary for survival . but leaves do n't contain much energy , and that which they do have is tough to extract . most herbivores supplement a leafy diet with higher energy foods like fruit and seeds . but sloths , especially three-toed sloths , rely on leaves almost exclusively . they 've evolved finely tuned strategies for coping with this restricted diet . first , they extract as much energy from their food as possible . sloths have a multi-chambered stomach that takes up a third of their body , and depending on the species , they can spend five to seven days , or even weeks , processing a meal . the other piece of the puzzle is to use as little energy as possible . one way sloths do this is , of course , by not moving very much . they spend most of their time eating , resting , or sleeping . they descend from the canopy just once a week for a bathroom break . when sloths do move , it 's not very fast . it would take a sloth about five minutes to cross an average neighborhood street . this unhurried approach to life means that sloths do n't need very much muscle . in fact , they have about 30 % less muscle mass than other animals their size . sloths also use less energy to keep themselves warm because their body temperature can fluctuate by about five degrees celsius , less than a cold-blooded reptile , but more than most mammals . these physical and behavioral adaptations minimize the sloth 's energy expenditure , or metabolic rate . three-toed sloths have the slowest metabolism of any mammal . the giant panda is second slowest , and two-toed sloths come in third . moving slowly has allowed sloths to thrive in their treetop habitat . but it 's also made the sloths themselves a great habitat for other organisms , including algae , which provides a little extra camouflage , and maybe even a snack . sloths may not be giant anymore , but that does n't make them any less remarkable .

but jefferson 's box of bones did n't come from a lion . they came from an extinct giant sloth . prehistoric ground sloths first appeared around 35 million years ago .

since sloths move so slowly , algae grow on their fur . in addition to algae , sloth fur is home to beetles , cockroaches , fungi , and moths . how does a sloth ’ s body act as an ecosystem ? what forms of symbiosis occur ?

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 .

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 .

which organism first dominated earth ?

are you afraid of black cats ? would you open an umbrella indoors ? and how do you feel about the number thirteen ? whether or not you believe in them , you 're probably familiar with a few of these superstitions . so how did it happen that people all over the world knock on wood , or avoid stepping on sidewalk cracks ? well , although they have no basis in science , many of these weirdly specific beliefs and practices do have equally weird and specific origins . because they involve supernatural causes , it 's no surprise that many superstitions are based in religion . for example . the number thirteen was associated with the biblical last supper , where jesus christ dined with his twelve disciples just before being arrested and crucified . the resulting idea that having thirteen people at a table was bad luck eventually expanded into thirteen being an unlucky number in general . now , this fear of the number thirteen , called triskaidekaphobia , is so common that many buildings around the world skip the thirteenth floor , with the numbers going straight from twelve to fourteen . of course , many people consider the story of the last supper to be true but other superstitions come from religious traditions that few people believe in or even remember . knocking on wood is thought to come from the folklore of the ancient indo-europeans or possibly people who predated them who believed that trees were home to various spirits . touching a tree would invoke the protection or blessing of the spirit within . and somehow , this tradition survived long after belief in these spirits had faded away . many superstitions common today in countries from russia to ireland are thought to be remnants of the pagan religions that christianity replaced . but not all superstitions are religious . some are just based on unfortunate coincidences and associations . for example , many italians fear the number 17 because the roman numeral xvii can be rearranged to form the word vixi , meaning my life had ended . similarly , the word for the number four sounds almost identical to the word for death in cantonese , as well as languages like japanese and korean that have borrowed chinese numerals . and since the number one also sounds like the word for must , the number fourteen sounds like the phrase must die . that 's a lot of numbers for elevators and international hotels to avoid . and believe it or not , some superstitions actually make sense , or at least they did until we forgot their original purpose . for example , theater scenery used to consist of large painted backdrops , raised and lowered by stagehands who would whistle to signal each other . absentminded whistles from other people could cause an accident . but the taboo against whistling backstage still exists today , long after the stagehands started using radio headsets . along the same lines , lighting three cigarettes from the same match really could cause bad luck if you were a soldier in a foxhole where keeping a match lit too long could draw attention from an enemy sniper . most smokers no longer have to worry about snipers , but the superstition lives on . so why do people cling to these bits of forgotten religions , coincidences , and outdated advice ? are n't they being totally irrational ? well , yes , but for many people , superstitions are based more on cultural habit than conscious belief . after all , no one is born knowing to avoid walking under ladders or whistling indoors , but if you grow up being told by your family to avoid these things , chances are they 'll make you uncomfortable , even after you logically understand that nothing bad will happen . and since doing something like knocking on wood does n't require much effort , following the superstition is often easier than consciously resisting it . besides , superstitions often do seem to work . maybe you remember hitting a home run while wearing your lucky socks . this is just our psychological bias at work . you 're far less likely to remember all the times you struck out while wearing the same socks . but believing that they work could actually make you play better by giving you the illusion of having greater control over events . so in situations where that confidence can make a difference , like sports , those crazy superstitions might not be so crazy after all .

many superstitions common today in countries from russia to ireland are thought to be remnants of the pagan religions that christianity replaced . but not all superstitions are religious . some are just based on unfortunate coincidences and associations .

which of the following superstitions was once good advice ?

this is a kindergarten we designed in 2007 . we made this kindergarten to be a circle . it 's a kind of endless circulation on top of the roof . if you are a parent , you know that kids love to keep making circles . this is how the rooftop looks . and why did we design this ? the principal of this kindergarten said , `` no , i do n't want a handrail . '' i said , `` it 's impossible . '' but he insisted : `` how about having a net sticking out from the edge of the roof ? so that it can catch the children falling off ? '' ( laughter ) i said , `` it 's impossible . '' and of course , the government official said , `` of course you have to have a handrail . '' but we could keep that idea around the trees . there are three trees popping through . and we were allowed to call this rope as a handrail . but of course , rope has nothing to do with them . they fall into the net . and you get more , and more , more . ( laughter ) sometimes 40 children are around a tree . the boy on the branch , he loves the tree so he is eating the tree . ( laughter ) and at the time of an event , they sit on the edge . it looks so nice from underneath . monkeys in the zoo . ( laughter ) feeding time . ( laughter ) ( applause ) and we made the roof as low as possible , because we wanted to see children on top of the roof , not only underneath the roof . and if the roof is too high , you see only the ceiling . and the leg washing place -- there are many kinds of water taps . you see with the flexible tubes , you want to spray water to your friends , and the shower , and the one in front is quite normal . but if you look at this , the boy is not washing his boots , he 's putting water into his boots . ( laughter ) this kindergarten is completely open , most of the year . and there is no boundary between inside and outside . so it means basically this architecture is a roof . and also there is no boundary between classrooms . so there is no acoustic barrier at all . when you put many children in a quiet box , some of them get really nervous . but in this kindergarten , there is no reason they get nervous . because there is no boundary . and the principal says if the boy in the corner does n't want to stay in the room , we let him go . he will come back eventually , because it 's a circle , it comes back . ( laughter ) but the point is , in that kind of occasion , usually children try to hide somewhere . but here , just they leave and come back . it 's a natural process . and secondly , we consider noise very important . you know that children sleep better in noise . they do n't sleep in a quiet space . and in this kindergarten , these children show amazing concentration in class . and you know , our kind grew up in the jungle with noise . they need noise . and you know , you can talk to your friends in a noisy bar . you are not supposed to be in silence . and you know , these days we are trying to make everything under control . you know , it 's completely open . and you should know that we can go skiing in -20 degrees in winter . in summer you go swimming . the sand is 50 degrees . and also , you should know that you are waterproof . you never melt in rain . so , children are supposed to be outside . so that is how we should treat them . this is how they divide classrooms . they are supposed to help teachers . they do n't . ( laughter ) i did n't put him in . a classroom . and a washbasin . they talk to each other around the well . and there are always some trees in the classroom . a monkey trying to fish another monkey from above . ( laughter ) monkeys . ( laughter ) and each classroom has at least one skylight . and this is where santa claus comes down at the time of christmas . this is the annex building , right next to that oval-shaped kindergarten . the building is only five meters tall with seven floors . and of course , the ceiling height is very low . so you have to consider safety . so , we put our children , a daughter and a son . they tried to go in . he hit his head . he 's okay . his skull is quite strong . he is resilient . it 's my son . ( laughter ) and he is trying to see if it is safe to jump off . and then we put other children . the traffic jam is awful in tokyo , as you know . ( laughter ) the driver in front , she needs to learn how to drive . now these days , kids need a small dosage of danger . and in this kind of occasion , they learn to help each other . this is society . this is the kind of opportunity we are losing these days . now , this drawing is showing the movement of a boy between 9:10 and 9:30 . and the circumference of this building is 183 meters . so it 's not exactly small at all . and this boy did 6,000 meters in the morning . but the surprise is yet to come . the children in this kindergarten do 4,000 meters on average . and these children have the highest athletic abilities among many kindergartens . the principal says , `` i do n't train them . we leave them on top of the roof . just like sheep . '' ( laughter ) they keep running . ( laughter ) my point is do n't control them , do n't protect them too much , and they need to tumble sometimes . they need to get some injury . and that makes them learn how to live in this world . i think architecture is capable of changing this world , and people 's lives . and this is one of the attempts to change the lives of children . thank you very much . ( applause )

this is a kindergarten we designed in 2007 . we made this kindergarten to be a circle .

when takaharu tezuka designed the kindergarten in 2007 , why did he and his team choose a circular formation for the building ?

translator : andrea mcdonough reviewer : bedirhan cinar what do horror movies and comedies have in common ? the two genres might seem totally different , but the reason they 're both so popular is perhaps because what they have in common : their use of dramatic irony . first , let 's clarify . there are three types of irony out there . situational irony is when you expect one thing , but get the opposite . verbal irony is when someone says something , but truly means the opposite . dramatic irony , though , is what we will be looking at right now . dramatic irony is when the audience seems to know more about an event , a situation , or a conversation than the characters in the movie , on the show , or in the book do . the audience is in on a secret that the characters have missed . this is a great story-telling device that creates tremendous emotion within that text . think about it for a moment . how does it feel when , in a horror film , you know that the scary villain is hiding behind that door in the darkened room . the music becomes eerie , the lighting creates complete shadows , this has to be bad for the hero ! of course , though , that hero must enter the room to find the villain . you feel tremendous tension and the suspense of knowing that someone will jump out and be scary , but you just do n't know when . that tension is dramatic irony : you know something more than the characters in the film . now , take the typical comedy . there will probably be some type of `` misunderstanding '' . again , we know more of what is going on than the characters do . picture two characters making a plan for a birthday surprise for their roommate while that roommate overhears the entire conversation from the hallway . from there , confusion and misunderstanding occur , and the tension builds . this is n't the same tension as the horror film since it is probably pretty funny as the character tries to figure out the whos and the whats , but it serves as a great example of the tension and suspense of dramatic irony . this tension or suspense in both genres drives the story and keeps the plot progressing . the audience wants , no , needs , to see the tension of the dramatic irony broken either by the scary person jumping out of the shadows or by someone finally revealing someone 's true identity and clearing up the confusion . so , when you feel like you are in on a secret , that is dramatic irony , a hallmark of all the great writers , from shakespeare to hitchcock .

you feel tremendous tension and the suspense of knowing that someone will jump out and be scary , but you just do n't know when . that tension is dramatic irony : you know something more than the characters in the film . now , take the typical comedy .

in a horror movie , suspense is often built by the use of music . the viewers often know that something is going to happen because of the music that they can hear -- and , of course , the characters can not hear this music . what are other devices that writers or filmmakers may use to build tension ( aka dramatic irony ) ?

it 's 4 a.m. , and the big test is in eight hours , followed by a piano recital . you 've been studying and playing for days , but you still do n't feel ready for either . so , what can you do ? well , you can drink another cup of coffee and spend the next few hours cramming and practicing , but believe it or not , you might be better off closing the books , putting away the music , and going to sleep . sleep occupies nearly a third of our lives , but many of us give surprisingly little attention and care to it . this neglect is often the result of a major misunderstanding . sleep is n't lost time , or just a way to rest when all our important work is done . instead , it 's a critical function , during which your body balances and regulates its vital systems , affecting respiration and regulating everything from circulation to growth and immune response . that 's great , but you can worry about all those things after this test , right ? well , not so fast . it turns out that sleep is also crucial for your brain , with a fifth of your body 's circulatory blood being channeled to it as you drift off . and what goes on in your brain while you sleep is an intensely active period of restructuring that 's crucial for how our memory works . at first glance , our ability to remember things does n't seem very impressive at all . 19th century psychologist herman ebbinghaus demonstrated that we normally forget 40 % of new material within the first twenty minutes , a phenomenon known as the forgetting curve . but this loss can be prevented through memory consolidation , the process by which information is moved from our fleeting short-term memory to our more durable long-term memory . this consolidation occurs with the help of a major part of the brain , known as the hippocampus . its role in long-term memory formation was demonstrated in the 1950s by brenda milner in her research with a patient known as h.m. after having his hippocampus removed , h.m. 's ability to form new short-term memories was damaged , but he was able to learn physical tasks through repetition . due to the removal of his hippocampus , h.m. 's ability to form long-term memories was also damaged . what this case revealed , among other things , was that the hippocampus was specifically involved in the consolidation of long-term declarative memory , such as the facts and concepts you need to remember for that test , rather than procedural memory , such as the finger movements you need to master for that recital . milner 's findings , along with work by eric kandel in the 90 's , have given us our current model of how this consolidation process works . sensory data is initially transcribed and temporarily recorded in the neurons as short-term memory . from there , it travels to the hippocampus , which strengthens and enhances the neurons in that cortical area . thanks to the phenomenon of neuroplasticity , new synaptic buds are formed , allowing new connections between neurons , and strengthening the neural network where the information will be returned as long-term memory . so why do we remember some things and not others ? well , there are a few ways to influence the extent and effectiveness of memory retention . for example , memories that are formed in times of heightened feeling , or even stress , will be better recorded due to the hippocampus ' link with emotion . but one of the major factors contributing to memory consolidation is , you guessed it , a good night 's sleep . sleep is composed of four stages , the deepest of which are known as slow-wave sleep and rapid eye movement . eeg machines monitoring people during these stages have shown electrical impulses moving between the brainstem , hippocampus , thalamus , and cortex , which serve as relay stations of memory formation . and the different stages of sleep have been shown to help consolidate different types of memories . during the non-rem slow-wave sleep , declarative memory is encoded into a temporary store in the anterior part of the hippocampus . through a continuing dialogue between the cortex and hippocampus , it is then repeatedly reactivated , driving its gradual redistribution to long-term storage in the cortex . rem sleep , on the other hand , with its similarity to waking brain activity , is associated with the consolidation of procedural memory . so based on the studies , going to sleep three hours after memorizing your formulas and one hour after practicing your scales would be the most ideal . so hopefully you can see now that skimping on sleep not only harms your long-term health , but actually makes it less likely that you 'll retain all that knowledge and practice from the previous night , all of which just goes to affirm the wisdom of the phrase , `` sleep on it . '' when you think about all the internal restructuring and forming of new connections that occurs while you slumber , you could even say that proper sleep will have you waking up every morning with a new and improved brain , ready to face the challenges ahead .

19th century psychologist herman ebbinghaus demonstrated that we normally forget 40 % of new material within the first twenty minutes , a phenomenon known as the forgetting curve . but this loss can be prevented through memory consolidation , the process by which information is moved from our fleeting short-term memory to our more durable long-term memory . this consolidation occurs with the help of a major part of the brain , known as the hippocampus .

using the same lists of tasks you stated in the previous question , determine which stage of sleep most likely encoded and consolidated the tasks as long-term memory .

if you line up the entire text of `` moby dick , '' which was published in 1851 , into a giant rectangle , you may notice some peculiar patterns , like these words , which seem to predict the assassination of martin luther king , or these references to the 1997 death of princess di . so , was herman melville a secret prophet ? the answer is no , and we know that thanks to a mathematical principle called ramsey theory . it 's the reason we can find geometric shapes in the night sky , it 's why we can know without checking that at least two people in london have exactly the same number of hairs on their head , and it explains why patterns can be found in just about any text , even vanilla ice lyrics . so what is ramsey theory ? simply put , it states that given enough elements in a set or structure , some particular interesting pattern among them is guaranteed to emerge . as a simple example , let 's look at what 's called the party problem , a classic illustration of ramsey theory . suppose there are at least six people at a party . amazingly enough , we can say for sure that some group of three of them either all know each other , or have never met before , without knowing a single thing about them . we can demonstrate that by graphing out all the possibilities . each point represents a person , and a line indicates that the pair know each other . every pair only has two possibilities : they either know each other or they do n't . there are a lot of possibilities , but every single one has the property that we 're looking for . six is the lowest number of guests where that 's guaranteed to be the case , which we can express like this . ramsey theory gives us a guarantee that such a minimum number exists for certain patterns , but no easy way to find it . in this case , as the total number of guests grows higher , the combinations get out of control . for instance , say you 're trying to find out the minimum size of a party where there 's a group of five people who all know each other or all do n't . despite five being a small number , the answer is virtually impossible to discover through an exhaustive search like this . that 's because of the sheer volume of possibilities . a party with 48 guests has 2^ ( 1128 ) possible configurations , more than the number of atoms in the universe . even with the help of computers , the best we know is that the answer to this question is somewhere between 43 and 49 guests . what this shows us is that specific patterns with seemingly astronomical odds can emerge from a relatively small set . and with a very large set , the possibilities are almost endless . any four stars where no three lie in a straight line will form some quadrilateral shape . expand that to the thousands of stars we can see in the sky , and it 's no surprise that we can find all sorts of familiar shapes , and even creatures if we look for them . so what are the chances of a text concealing a prophecy ? well , when you factor in the number of letters , the variety of possible related words , and all their abbreviations and alternate spellings , they 're pretty high . you can try it yourself . just pick a favorite text , arrange the letters in a grid , and see what you can find . the mathematician t.s . motzkin once remarked that , `` while disorder is more probable in general , complete disorder is impossible . '' the sheer size of the universe guarantees that some of its random elements will fall into specific arrangements , and because we evolved to notice patterns and pick out signals among the noise , we are often tempted to find intentional meaning where there may not be any . so while we may be awed by hidden messages in everything from books , to pieces of toast , to the night sky , their real origin is usually our own minds .

simply put , it states that given enough elements in a set or structure , some particular interesting pattern among them is guaranteed to emerge . as a simple example , let 's look at what 's called the party problem , a classic illustration of ramsey theory . suppose there are at least six people at a party .

according to the ramsey theory and the “ party problem , ” in a group of six party goers which statement is true ?

one of the most remarkable aspects of the human brain is its ability to recognize patterns and describe them . among the hardest patterns we 've tried to understand is the concept of turbulent flow in fluid dynamics . the german physicist werner heisenberg said , `` when i meet god , i 'm going to ask him two questions : why relativity and why turbulence ? i really believe he will have an answer for the first . '' as difficult as turbulence is to understand mathematically , we can use art to depict the way it looks . in june 1889 , vincent van gogh painted the view just before sunrise from the window of his room at the saint-paul-de-mausole asylum in saint-rémy-de-provence , where he 'd admitted himself after mutilating his own ear in a psychotic episode . in `` the starry night , '' his circular brushstrokes create a night sky filled with swirling clouds and eddies of stars . van gogh and other impressionists represented light in a different way than their predecessors , seeming to capture its motion , for instance , across sun-dappled waters , or here in star light that twinkles and melts through milky waves of blue night sky . the effect is caused by luminance , the intensity of the light in the colors on the canvas . the more primitive part of our visual cortex , which sees light contrast and motion , but not color , will blend two differently colored areas together if they have the same luminance . but our brains ' primate subdivision will see the contrasting colors without blending . with these two interpretations happening at once , the light in many impressionist works seems to pulse , flicker and radiate oddly . that 's how this and other impressionist works use quickly executed prominent brushstrokes to capture something strikingly real about how light moves . 60 years later , russian mathematician andrey kolmogorov furthered our mathematical understanding of turbulence when he proposed that energy in a turbulent fluid at length r varies in proportion to the 5/3rds power of r. experimental measurements show kolmogorov was remarkably close to the way turbulent flow works , although a complete description of turbulence remains one of the unsolved problems in physics . a turbulent flow is self-similar if there is an energy cascade . in other words , big eddies transfer their energy to smaller eddies , which do likewise at other scales . examples of this include jupiter 's great red spot , cloud formations and interstellar dust particles . in 2004 , using the hubble space telescope , scientists saw the eddies of a distant cloud of dust and gas around a star , and it reminded them of van gogh 's `` starry night . '' this motivated scientists from mexico , spain and england to study the luminance in van gogh 's paintings in detail . they discovered that there is a distinct pattern of turbulent fluid structures close to kolmogorov 's equation hidden in many of van gogh 's paintings . the researchers digitized the paintings , and measured how brightness varies between any two pixels . from the curves measured for pixel separations , they concluded that paintings from van gogh 's period of psychotic agitation behave remarkably similar to fluid turbulence . his self-portrait with a pipe , from a calmer period in van gogh 's life , showed no sign of this correspondence . and neither did other artists ' work that seemed equally turbulent at first glance , like munch 's `` the scream . '' while it 's too easy to say van gogh 's turbulent genius enabled him to depict turbulence , it 's also far too difficult to accurately express the rousing beauty of the fact that in a period of intense suffering , van gogh was somehow able to perceive and represent one of the most supremely difficult concepts nature has ever brought before mankind , and to unite his unique mind 's eye with the deepest mysteries of movement , fluid and light .

that 's how this and other impressionist works use quickly executed prominent brushstrokes to capture something strikingly real about how light moves . 60 years later , russian mathematician andrey kolmogorov furthered our mathematical understanding of turbulence when he proposed that energy in a turbulent fluid at length r varies in proportion to the 5/3rds power of r. experimental measurements show kolmogorov was remarkably close to the way turbulent flow works , although a complete description of turbulence remains one of the unsolved problems in physics . a turbulent flow is self-similar if there is an energy cascade . in other words , big eddies transfer their energy to smaller eddies , which do likewise at other scales .

research the idea of statistical self-similarity . what are some examples of turbulence that are not shown in the video ?

imagine setting sail from hawaii in a canoe . your target is a small island thousands of kilometers away in the middle of the pacific ocean . that 's a body of water that covers more than 160 million square kilometers , greater than all the landmasses on earth combined . for thousands of years , polynesian navigators managed voyages like this without the help of modern navigational aids . ancient polynesians used the sun , moon , stars , planets , ocean currents , and clouds as guides that allowed them to see the ocean as a series of pathways rather than an obstacle . their voyages began around 1500 b.c . when the people who would settle polynesia first set sail from southeast asia . early polynesians eventually settled a vast area of islands spread over 40 million square kilometers of the pacific ocean . some historians believe the voyagers moved from place to place to avoid overpopulation . others , that they were driven by war . voyages became less frequent by around 1300 a.d. as polynesian societies became more rooted in specific locations . during the voyaging period , successful journeys depended on a number of factors : well-built canoes , the skill of navigators , and weather being some of the biggest . voyages relied on sturdy wa'a kaulua , or double-hulled canoes , which were powered by sails and steered with a single large oar . canoe building involved the whole community , bringing together the navigators , canoe builders , priests , chanters , and hula dancers . navigators were keen observers of the natural world . they were abundantly familiar with trade wind-generated ocean swells , which typically flow northeast or southeast . by day , navigators could identify direction by the rocking motion of their canoes caused by these swells . but sunrise and sunset were even more useful . the sun 's position indicated east and west and created low light on the ocean that made it possible to see swells directly . at night , navigators used something called a star compass , which was n't a physical object , but rather a sort of mental map . they memorized the rising and setting points of stars and constellations at different times of the year . they used those to divide the sky into four quadrants , subdivided into 32 houses , with the canoe in the middle . so , for example , when they saw the star pira ‘ atea rising from the ocean , they knew that to be northeast . they had some other tricks , too . the earth 's axis points towards hokupa'a , or the north star , so called because it 's the one fixed point in the sky as the earth rotates and always indicates north . however , it 's not visible south of the equator , so navigators there could use a constellation called newe , or the southern cross , and some mental tricks to estimate where south is . for instance , draw a line through these two stars , extend it 4.5 times , and draw another line from there to the horizon . that 's south . but the sky also contains navigational aids much closer to earth , the clouds . besides being useful weather cues , under the right conditions , they can indicate landmasses . for instance , the lagoons of pacific atolls can actually be seen reflected on the underside of clouds , if you know what to look for . and high masses of clouds can indicate mountainous islands . once navigators neared their destination , other clues , such as the flight patterns of birds , floating debris or vegetation , and types of fish in the area helped determine the proximity of land . for example , the manu-o-ku had a known flight range of 190 kilometers , and could be followed back to shore . so how do we know all of this ? partially through evidence in petroglyphs , written observations of european explorers , and polynesian oral traditions . but also by trying them out for ourselves . in 2017 , a voyaging canoe called hokulea completed a worldwide voyage using only these techniques . if that seems remarkable , remember the ancient polynesians , who through close study and kinship with nature , were able to forge these paths across an unfathomably vast , vibrant living ocean .

imagine setting sail from hawaii in a canoe . your target is a small island thousands of kilometers away in the middle of the pacific ocean .

some voyages lasted up to 30 days . what would be some things to consider before setting sail ?

when french mathematician laurent schwartz was in high school , he started to worry that he was n't smart enough to solve math problems . maybe you know a similar feeling . you sit down to take a math test , and you feel your heart beat faster and your palms start to sweat . you get butterflies in your stomach , and you ca n't concentrate . this phenomenon is called math anxiety , and if it happens to you , you 're not alone . researchers think about 20 % of the population suffers from it . some psychologists even consider it a diagnosable condition . but having mathematical anxiety does n't necessarily mean you 're bad at math - not even close . laurent schwartz went on to win the fields medal , the highest award in mathematics . people might think that they 're anxious about math because they 're bad at it , but it 's often the other way around . they 're doing poorly in math because they 're anxious about it . some psychologists think that 's because math anxiety decreases a cognitive resource called working memory . that 's the short-term memory system that helps you organize the information you need to complete a task . worrying about being able to solve math problems , or not doing well on a test , eats up working memory , leaving less of it available to tackle the math itself . people can suddenly struggle with even basic math skills , like arithmetic , that they 've otherwise mastered . academic anxiety certainly is n't limited to math , but it does seem to happen much more frequently , and cause more harm in that subject . so why would that be ? researchers are n't yet sure , but some studies suggest that the way children are exposed to math by their parents and teachers play a large part . if parents talk about math like something challenging and unfamiliar , children can internalize that . teachers with math anxiety are also likely to spread it to their students . pressure to solve problems quickly dials up stress even more . and in some cultures , being good at math is a sign of being smart in general . when the stakes are that high , it 's not surprising that students are anxious . even maryam mirzakhani , an influential mathematician who was the first woman to win the fields medal , felt unconfident and lost interest in mathematics because her math teacher in middle school did n't think she was talented . so if you experience mathematical anxiety , what can you do ? relaxation techniques , like short breathing exercises , have improved test performance in students with math anxiety . writing down your worries can also help . this strategy may give you a chance to reevaluate a stressful experience , freeing up working memory . and if you have the chance , physical activity , like a brisk walk , deepens breathing and helps relieve muscle tension , preventing anxiety from building . you can also use your knowledge about the brain to change your mindset . the brain is flexible , and the areas involved in math skills can always grow and develop . this is a psychological principle called the growth mindset . thinking of yourself as someone who can grow and improve can actually help you grow and improve . if you 're a teacher or parent of young children , try being playful with math and focusing on the creative aspects . that can build the numerical skills that help students approach math with confidence later on . importantly , you should give children the time and space to work through their answers . and if you 're an administrator , make sure your teachers have the positive attitudes and mathematical confidence necessary to inspire confidence in all of their students . also , do n't let anyone spread the myth that boys are innately better than girls at math . that is completely false . if you experience math anxiety , it may not help to just know that math anxiety exists . or perhaps it 's reassuring to put a name to the problem . regardless , if you take a look around yourself , the odds are good that you 'll see someone experiencing the same thing as you . just remember that the anxiety is not a reflection of your ability , but it is something you can conquer with time and awareness .

that is completely false . if you experience math anxiety , it may not help to just know that math anxiety exists . or perhaps it 's reassuring to put a name to the problem .

math anxiety may hinder mathematical achievements since :

just now , somewhere in the universe , a star exploded . there goes another one . in fact , a supernova occurs every second or so in the observable universe , and there is one on average every 25 to 50 years in a galaxy the size and age of the milky way . yet we 've never actually been able to watch one happen from its first violent moments . of course , how would we ? there are hundreds of billions of stars close enough that we could watch the supernova explosion break through the surface of the star . but we 'd have to have our best telescopes focused on the right one at precisely the right time to get meaningful data . suffice it to say , the odds of that happening are astronomically low . but what if we could anticipate a supernova before its light reached us ? that may seem impossible . after all , nothing travels faster than the speed of light , right ? as far as we know , yes . but in a race , fast does n't matter if you take a detour while someone else beelines it for the finish line . for exactly that reason , photons do n't win the supernova race to earth . neutrinos do . here 's why . there are two types of supernova . type 1 is when a star accumulates so much matter from a neighboring star , that a runaway nuclear reaction ignites and causes it to explode . in type 2 , the star runs out of nuclear fuel , so the gravitational forces pulling in overwhelm the quantum mechanical forces pushing out , and the stellar core collapses under its own weight in a hundredth of a second . while the outer reaches of the star are unaffected by the collapsed core , the inner edges accelerate through the void , smash into the core , and rebound to launch the explosion . in both of these scenarios , the star expels an unparalleled amount of energy , as well as a great deal of matter . in fact , all atoms heavier than nickel , including elements like gold and silver , only form in supernova reactions . in type 2 supernovae , about 1 % of the energy consists of photons , which we know of as light , while 99 % radiates out as neutrinos , the elementary particles that are known for rarely interacting with anything . starting from the center of the star , the exploding matter takes tens of minutes , or even hours , or in rare cases , several days , to reach and break through the surface of the star . however , the neutrinos , thanks to their non-interactivity , take a much more direct route . by the time there is any visible change in the star 's suface , the neutrinos typically have a several hour head start over the photons . that 's why astronomers and physicists have been able to set up a project called snews , the supernova early warning system . when detectors around the world pick up bursts of neutrinos , they send messages to a central computer in new york . if multiple detectors receive similar signals within ten seconds , snews will trigger an alert warning that a supernova is imminent . aided by some distance and direction information from the neutrino detectors , the amateur astronomers and scientists alike will scan the skies and share information to quickly identify the new galactic supernova and turn the world 's major telescopes in that direction . the last supernova that sent detectable neutrinos to earth was in 1987 on the edge of the tarantula nebula in the large magellanic cloud , a nearby galaxy . its neutrinos reached earth about three hours ahead of the visible light . we 're due for another one any day now , and when that happens , snews should give you the opportunity to be among the first to witness something that no human has ever seen before .

in both of these scenarios , the star expels an unparalleled amount of energy , as well as a great deal of matter . in fact , all atoms heavier than nickel , including elements like gold and silver , only form in supernova reactions . in type 2 supernovae , about 1 % of the energy consists of photons , which we know of as light , while 99 % radiates out as neutrinos , the elementary particles that are known for rarely interacting with anything . starting from the center of the star , the exploding matter takes tens of minutes , or even hours , or in rare cases , several days , to reach and break through the surface of the star .

what is the main difference between type 1 and a type 2 supernova ?

you 're looking at a woman who was publicly silent for a decade . obviously , that 's changed , but only recently . it was several months ago that i gave my very first major public talk at the forbes 30 under 30 summit : 1,500 brilliant people , all under the age of 30 . that meant that in 1998 , the oldest among the group were only 14 , and the youngest , just four . i joked with them that some might only have heard of me from rap songs . yes , i 'm in rap songs . almost 40 rap songs . ( laughter ) but the night of my speech , a surprising thing happened . at the age of 41 , i was hit on by a 27-year-old guy . i know , right ? he was charming and i was flattered , and i declined . you know what his unsuccessful pickup line was ? he could make me feel 22 again . ( laughter ) ( applause ) i realized later that night , i 'm probably the only person over 40 who does not want to be 22 again . ( laughter ) ( applause ) at the age of 22 , i fell in love with my boss , and at the age of 24 , i learned the devastating consequences . can i see a show of hands of anyone here who did n't make a mistake or do something they regretted at 22 ? yep . that 's what i thought . so like me , at 22 , a few of you may have also taken wrong turns and fallen in love with the wrong person , maybe even your boss . unlike me , though , your boss probably was n't the president of the united states of america . of course , life is full of surprises . not a day goes by that i 'm not reminded of my mistake , and i regret that mistake deeply . in 1998 , after having been swept up into an improbable romance , i was then swept up into the eye of a political , legal and media maelstrom like we had never seen before . remember , just a few years earlier , news was consumed from just three places : reading a newspaper or magazine , listening to the radio , or watching television . that was it . but that was n't my fate . instead , this scandal was brought to you by the digital revolution . that meant we could access all the information we wanted , when we wanted it , anytime , anywhere , and when the story broke in january 1998 , it broke online . it was the first time the traditional news was usurped by the internet for a major news story , a click that reverberated around the world . what that meant for me personally was that overnight i went from being a completely private figure to a publicly humiliated one worldwide . i was patient zero of losing a personal reputation on a global scale almost instantaneously . this rush to judgment , enabled by technology , led to mobs of virtual stone-throwers . granted , it was before social media , but people could still comment online , email stories , and , of course , email cruel jokes . news sources plastered photos of me all over to sell newspapers , banner ads online , and to keep people tuned to the tv . do you recall a particular image of me , say , wearing a beret ? now , i admit i made mistakes , especially wearing that beret . but the attention and judgment that i received , not the story , but that i personally received , was unprecedented . i was branded as a tramp , tart , slut , whore , bimbo , and , of course , that woman . i was seen by many but actually known by few . and i get it : it was easy to forget that that woman was dimensional , had a soul , and was once unbroken . when this happened to me 17 years ago , there was no name for it . now we call it cyberbullying and online harassment . today , i want to share some of my experience with you , talk about how that experience has helped shape my cultural observations , and how i hope my past experience can lead to a change that results in less suffering for others . in 1998 , i lost my reputation and my dignity . i lost almost everything , and i almost lost my life . let me paint a picture for you . it is september of 1998 . i 'm sitting in a windowless office room inside the office of the independent counsel underneath humming fluorescent lights . i 'm listening to the sound of my voice , my voice on surreptitiously taped phone calls that a supposed friend had made the year before . i 'm here because i 've been legally required to personally authenticate all 20 hours of taped conversation . for the past eight months , the mysterious content of these tapes has hung like the sword of damocles over my head . i mean , who can remember what they said a year ago ? scared and mortified , i listen , listen as i prattle on about the flotsam and jetsam of the day ; listen as i confess my love for the president , and , of course , my heartbreak ; listen to my sometimes catty , sometimes churlish , sometimes silly self being cruel , unforgiving , uncouth ; listen , deeply , deeply ashamed , to the worst version of myself , a self i do n't even recognize . a few days later , the starr report is released to congress , and all of those tapes and transcripts , those stolen words , form a part of it . that people can read the transcripts is horrific enough , but a few weeks later , the audio tapes are aired on tv , and significant portions made available online . the public humiliation was excruciating . life was almost unbearable . this was not something that happened with regularity back then in 1998 , and by this , i mean the stealing of people 's private words , actions , conversations or photos , and then making them public -- public without consent , public without context , and public without compassion . fast forward 12 years to 2010 , and now social media has been born . the landscape has sadly become much more populated with instances like mine , whether or not someone actually make a mistake , and now it 's for both public and private people . the consequences for some have become dire , very dire . i was on the phone with my mom in september of 2010 , and we were talking about the news of a young college freshman from rutgers university named tyler clementi . sweet , sensitive , creative tyler was secretly webcammed by his roommate while being intimate with another man . when the online world learned of this incident , the ridicule and cyberbullying ignited . a few days later , tyler jumped from the george washington bridge to his death . he was 18 . my mom was beside herself about what happened to tyler and his family , and she was gutted with pain in a way that i just could n't quite understand , and then eventually i realized she was reliving 1998 , reliving a time when she sat by my bed every night , reliving a time when she made me shower with the bathroom door open , and reliving a time when both of my parents feared that i would be humiliated to death , literally . today , too many parents have n't had the chance to step in and rescue their loved ones . too many have learned of their child 's suffering and humiliation after it was too late . tyler 's tragic , senseless death was a turning point for me . it served to recontextualize my experiences , and i then began to look at the world of humiliation and bullying around me and see something different . in 1998 , we had no way of knowing where this brave new technology called the internet would take us . since then , it has connected people in unimaginable ways , joining lost siblings , saving lives , launching revolutions , but the darkness , cyberbullying , and slut-shaming that i experienced had mushroomed . every day online , people , especially young people who are not developmentally equipped to handle this , are so abused and humiliated that they ca n't imagine living to the next day , and some , tragically , do n't , and there 's nothing virtual about that . childline , a u.k. nonprofit that 's focused on helping young people on various issues , released a staggering statistic late last year : from 2012 to 2013 , there was an 87 percent increase in calls and emails related to cyberbullying . a meta-analysis done out of the netherlands showed that for the first time , cyberbullying was leading to suicidal ideations more significantly than offline bullying . and you know what shocked me , although it should n't have , was other research last year that determined humiliation was a more intensely felt emotion than either happiness or even anger . cruelty to others is nothing new , but online , technologically enhanced shaming is amplified , uncontained , and permanently accessible . the echo of embarrassment used to extend only as far as your family , village , school or community , but now it 's the online community too . millions of people , often anonymously , can stab you with their words , and that 's a lot of pain , and there are no perimeters around how many people can publicly observe you and put you in a public stockade . there is a very personal price to public humiliation , and the growth of the internet has jacked up that price . for nearly two decades now , we have slowly been sowing the seeds of shame and public humiliation in our cultural soil , both on- and offline . gossip websites , paparazzi , reality programming , politics , news outlets and sometimes hackers all traffic in shame . it 's led to desensitization and a permissive environment online which lends itself to trolling , invasion of privacy , and cyberbullying . this shift has created what professor nicolaus mills calls a culture of humiliation . consider a few prominent examples just from the past six months alone . snapchat , the service which is used mainly by younger generations and claims that its messages only have the lifespan of a few seconds . you can imagine the range of content that that gets . a third-party app which snapchatters use to preserve the lifespan of the messages was hacked , and 100,000 personal conversations , photos , and videos were leaked online to now have a lifespan of forever . jennifer lawrence and several other actors had their icloud accounts hacked , and private , intimate , nude photos were plastered across the internet without their permission . one gossip website had over five million hits for this one story . and what about the sony pictures cyberhacking ? the documents which received the most attention were private emails that had maximum public embarrassment value . but in this culture of humiliation , there is another kind of price tag attached to public shaming . the price does not measure the cost to the victim , which tyler and too many others , notably women , minorities , and members of the lgbtq community have paid , but the price measures the profit of those who prey on them . this invasion of others is a raw material , efficiently and ruthlessly mined , packaged and sold at a profit . a marketplace has emerged where public humiliation is a commodity and shame is an industry . how is the money made ? clicks . the more shame , the more clicks . the more clicks , the more advertising dollars . we 're in a dangerous cycle . the more we click on this kind of gossip , the more numb we get to the human lives behind it , and the more numb we get , the more we click . all the while , someone is making money off of the back of someone else 's suffering . with every click , we make a choice . the more we saturate our culture with public shaming , the more accepted it is , the more we will see behavior like cyberbullying , trolling , some forms of hacking , and online harassment . why ? because they all have humiliation at their cores . this behavior is a symptom of the culture we 've created . just think about it . changing behavior begins with evolving beliefs . we 've seen that to be true with racism , homophobia , and plenty of other biases , today and in the past . as we 've changed beliefs about same-sex marriage , more people have been offered equal freedoms . when we began valuing sustainability , more people began to recycle . so as far as our culture of humiliation goes , what we need is a cultural revolution . public shaming as a blood sport has to stop , and it 's time for an intervention on the internet and in our culture . the shift begins with something simple , but it 's not easy . we need to return to a long-held value of compassion -- compassion and empathy . online , we 've got a compassion deficit , an empathy crisis . researcher brené brown said , and i quote , `` shame ca n't survive empathy . '' shame can not survive empathy . i 've seen some very dark days in my life , and it was the compassion and empathy from my family , friends , professionals , and sometimes even strangers that saved me . even empathy from one person can make a difference . the theory of minority influence , proposed by social psychologist serge moscovici , says that even in small numbers , when there 's consistency over time , change can happen . in the online world , we can foster minority influence by becoming upstanders . to become an upstander means instead of bystander apathy , we can post a positive comment for someone or report a bullying situation . trust me , compassionate comments help abate the negativity . we can also counteract the culture by supporting organizations that deal with these kinds of issues , like the tyler clementi foundation in the u.s. , in the u.k. , there 's anti-bullying pro , and in australia , there 's project rockit . we talk a lot about our right to freedom of expression , but we need to talk more about our responsibility to freedom of expression . we all want to be heard , but let 's acknowledge the difference between speaking up with intention and speaking up for attention . the internet is the superhighway for the id , but online , showing empathy to others benefits us all and helps create a safer and better world . we need to communicate online with compassion , consume news with compassion , and click with compassion . just imagine walking a mile in someone else 's headline . i 'd like to end on a personal note . in the past nine months , the question i 've been asked the most is why . why now ? why was i sticking my head above the parapet ? you can read between the lines in those questions , and the answer has nothing to do with politics . the top note answer was and is because it 's time : time to stop tip-toeing around my past ; time to stop living a life of opprobrium ; and time to take back my narrative . it 's also not just about saving myself . anyone who is suffering from shame and public humiliation needs to know one thing : you can survive it . i know it 's hard . it may not be painless , quick or easy , but you can insist on a different ending to your story . have compassion for yourself . we all deserve compassion , and to live both online and off in a more compassionate world . thank you for listening . ( applause )

at the age of 41 , i was hit on by a 27-year-old guy . i know , right ? he was charming and i was flattered , and i declined .

how is the internet impacting an individual 's right to privacy ?

here at scishow hq we have a little food area for the employees - sometimes there are donuts . sometimes there are nuts . sometimes dried mango . but the one thing that never sticks around and is gone as soon as we can buy it is the wonderful , beautiful , noble banana . unfortunately for us , they may not be around forever . [ intro music ] first , the good : bananas are healthy , packed with nutrition and energy , they fit in your hand and give nice little cues when they 're perfectly ripe , and are easy to peel and eat ; shocking statistic , the banana is wal-mart 's number one selling item . not the potato chip , not coca-cola , not fifty shades of grey , bananas . they appear to be so perfect for human consumption that kirk cameron attempted to use them to prove the existence of god . of course this banana was not created by god , or really even nature . bananas , at least the ones that you see at the store , were created by people . do n't get me wrong , there are wild banana plants - lots of them - they 're native to south and southeast asia , and there are dozens of species and thousands of varieties . they 're just not the ones we eat . some those species , as you might suspect , have seeds , 'cause that 's what fruits are , they 're fleshy bodies containing seeds . so you might wonder , why have you never eaten a banana seed ? well , you have ... kinda . in cultivated bananas the seeds have pretty much stopped existing . if you look closely you can see tiny black specks . those are all that 's left , and they 're not fertile seeds . if you plant them , nothing grows . today 's bananas are sterile mutants . i 'm not trying to be mean , that 's just the truth . unless you were alive in the 1960 's ( hats off to all those older scishow viewers out there ) every banana you have ever eaten was pretty much genetically identical . this is a cavendish , the virtually seedless variety that we all eat today , but it was n't always our banana of choice . until the 1960s , everyone was eating the same banana , it was just a different banana - the gros michel , a bigger , sweeter fruit with thicker skin . you might notice that banana flavored things do n't really taste like bananas . well they do - they taste like the gros michel . the genetic monotony of the gros michel crop was its undoing . a fungicide resistant pathogen called the panama disease began infecting gros michel crop . by the time growers understood how vulnerable their crops were , the gros michel variety was all but extinct . the entire banana industry had to be retooled for the cavendish . since they 're seedless , the only way to reproduce them is to transplant part of the plant stem , and for the last 50 years we 've been good with the cavendish , 'cause it 's more resistant to the panama disease . however somewhat terrifyingly a strain of panama disease that affects the cavendish strain that we all eat has been identified . a global monoculture of genetically identical individuals is a beautiful sight to a pathogen . the fungus only has to figure out how to infect and destroy a single individual , and suddenly there is no diversity to stop it , or even slow it down . that 's led to a lot of scientists worrying about or even predicting the outright demise of the cavendish . this wonderful most popular of fruits might completely cease existence . the good news is we now have a much better understanding of genetics , epidemics , fungi , and pathology . scientists and growers have already taken steps to protect the cavendish . some growers are creating genetically different bananas that might replace the cavendish crop if it fails , while scientists are attempting to genetically engineer cavendish plants with immunity to panama disease . plus we learned a lot from the gros michel debacle . infected fields are quickly being destroyed and new crops are grown from pathogen-free lab-grown plant stock . so thanks to the people who work tirelessly to grow and harvest bananas and bring them to us so that we can offer them inexpensively to our employees , and thanks to the growers and scientists working tirelessly to make sure that they do n't go the way of the gros michel . thanks for watching this episode of scishow , if you have any questions , comments or suggestions for us , you can find us on facebook , twitter or in the comments below , and if you want to continue getting smarter this year at scishow , you can go to youtube.com/scishow and subscribe . [ banana eating noises ] [ music ]

scientists and growers have already taken steps to protect the cavendish . some growers are creating genetically different bananas that might replace the cavendish crop if it fails , while scientists are attempting to genetically engineer cavendish plants with immunity to panama disease . plus we learned a lot from the gros michel debacle .

8. why is it important to create genetically different bananas in case the cavendish crop fails ? why is genetic diversity so important ?

every day , a sea of decisions stretches before us . some are small and unimportant , but others have a larger impact on our lives . for example , which politician should i vote for ? should i try the latest diet craze ? or will email make me a millionaire ? we 're bombarded with so many decisions that it 's impossible to make a perfect choice every time . but there are many ways to improve our chances , and one particularly effective technique is critical thinking . this is a way of approaching a question that allows us to carefully deconstruct a situation , reveal its hidden issues , such as bias and manipulation , and make the best decision . if the critical part sounds negative that 's because in a way it is . rather than choosing an answer because it feels right , a person who uses critical thinking subjects all available options to scrutiny and skepticism . using the tools at their disposal , they 'll eliminate everything but the most useful and reliable information . there are many different ways of approaching critical thinking , but here 's one five-step process that may help you solve any number of problems . one : formulate your question . in other words , know what you 're looking for . this is n't always as straightforward as it sounds . for example , if you 're deciding whether to try out the newest diet craze , your reasons for doing so may be obscured by other factors , like claims that you 'll see results in just two weeks . but if you approach the situation with a clear view of what you 're actually trying to accomplish by dieting , whether that 's weight loss , better nutrition , or having more energy , that 'll equip you to sift through this information critically , find what you 're looking for , and decide whether the new fad really suits your needs . two : gather your information . there 's lots of it out there , so having a clear idea of your question will help you determine what 's relevant . if you 're trying to decide on a diet to improve your nutrition , you may ask an expert for their advice , or seek other people 's testimonies . information gathering helps you weigh different options , moving you closer to a decision that meets your goal . three : apply the information , something you do by asking critical questions . facing a decision , ask yourself , `` what concepts are at work ? '' `` what assumptions exist ? '' `` is my interpretation of the information logically sound ? '' for example , in an email that promises you millions , you should consider , `` what is shaping my approach to this situation ? '' `` do i assume the sender is telling the truth ? '' `` based on the evidence , is it logical to assume i 'll win any money ? '' four : consider the implications . imagine it 's election time , and you 've selected a political candidate based on their promise to make it cheaper for drivers to fill up on gas . at first glance , that seems great . but what about the long-term environmental effects ? if gasoline use is less restricted by cost , this could also cause a huge surge in air pollution , an unintended consequence that 's important to think about . five : explore other points of view . ask yourself why so many people are drawn to the policies of the opposing political candidate . even if you disagree with everything that candidate says , exploring the full spectrum of viewpoints might explain why some policies that do n't seem valid to you appeal to others . this will allow you to explore alternatives , evaluate your own choices , and ultimately help you make more informed decisions . this five-step process is just one tool , and it certainly wo n't eradicate difficult decisions from our lives . but it can help us increase the number of positive choices we make . critical thinking can give us the tools to sift through a sea of information and find what we 're looking for . and if enough of us use it , it has the power to make the world a more reasonable place .

using the tools at their disposal , they 'll eliminate everything but the most useful and reliable information . there are many different ways of approaching critical thinking , but here 's one five-step process that may help you solve any number of problems . one : formulate your question .

what is the first step ( of five ) in the critical thinking process ?

an estimated 20 million cases of blindness worldwide are caused by cataracts , a curable condition affecting the lens that focuses images onto the eye 's retina . a cataract occurs when proteins in the lens lose their normal arrangement , clumping together in a way that causes discoloration or clouding , and eventually blocks most vision . cataracts can be caused by eye injury , certain medications , ultraviolet radiation , diabetes , smoking , or some genetic disorders . but the most common cause is aging . in the united states , more than 50 % of people over the age of 80 develop them . cataracts were treated over 2,500 years ago in india , though similar procedures may have existed even earlier in ancient egypt and babylon . the most common procedure , called couching , involved pressing a sharp instrument into the eye to loosen and push the clouded lens out of the way . although this could increase the amount of light entering the eye , the lack of a lens would leave the patient 's vision out of focus . despite its low success rate , and high risk of infection or injury , couching is still performed in some parts of the world . later procedures would also focus on removing the cloudy lens , for example , by making an opening in the cornea to pull out the lens along with the membrane capsule surrounding it . while the invention of eyeglasses allowed for some restoration of focus , they had to be extremely thick to help . furthermore , such techniques still caused complications , like damaging the retina , or leaving the eye with uncomfortable stitches . but in the 20th century , something unexpected happened . eye surgeon sir harold ridley was treating world war ii casualties when he noticed that acrylic plastic from a shattered aircraft cockpit had become lodged in a pilot 's eyes without triggering an adverse reaction . this led him to propose surgically implanting artificial lenses into the eye to replace cataracts . and despite initial resistance , the method became standard practice by the 1980s . since ridley 's discovery , the intraocular lens has undergone several improvements . modern lenses can fit into the membrane capsule that the cataract is extracted from , leaving more of the eye 's natural anatomy intact . and the ability to fine-tune the lens curvature allows the surgery to restore a patient 's normal vision without the need for glasses . of course , surgical techniques have also progressed . microscopic procedures use small instruments or lasers to make precise incisions of one or two millimeters in the cornea , while an ultrasound probe breaks up and removes the cataracted lens with minimal trauma to the eye . low-tech versions of this operation have made the surgery quick and inexpensive , helping it spread across the developing world . places like aravind eye hospital in india have pioneered high-volume , low-cost cataract surgery for as little as six dollars . why then , with all these advances , are there still so many blind people in the world ? the main issue is access to health care , with poor infrastructure and a shortage of doctors being a major barrier in many regions . but this is not the only problem . in many rural areas with poor education , blindness is often accepted as an inevitable part of aging , for which someone might not think to seek treatment . this is why information is crucial . increased community awareness programs and the spread of mobile phones mean that many of those who might have remained blind for the rest of their lives due to cataracts are now reachable . and for them , a brighter future is in sight .

microscopic procedures use small instruments or lasers to make precise incisions of one or two millimeters in the cornea , while an ultrasound probe breaks up and removes the cataracted lens with minimal trauma to the eye . low-tech versions of this operation have made the surgery quick and inexpensive , helping it spread across the developing world . places like aravind eye hospital in india have pioneered high-volume , low-cost cataract surgery for as little as six dollars . why then , with all these advances , are there still so many blind people in the world ?

having a high-quality operation available for cataract surgery in low-income countries is part of the solution to reducing cataract blindness . however , despite the availability of these procedures , many people remain blind . what other barriers exist to cataract blind individuals actually receiving their required surgery ?

translator : andrea mcdonough reviewer : jessica ruby the world we live in is made of things , billions and billions of different things , like pickles and pianos and dump trucks and octopi . and even though these things seem totally different , they 're all made of the same stuff , just combined in different ways . to give you an idea of how this combining works , let 's take something apart . let 's start with this bowl of macaroni salad . if you were to reverse a recipe for macaroni salad , you 'll see it 's made by mixing together a bunch of ingredients , like macaroni , mayo , vinegar , vegetables , and mustard . this type of combining is called a mixture . when you make a mixture , you 're combining two or more things together without actually changing the chemical identity of those things . like mud , for example . the soil and water in mud have n't actually changed . they 're still soil and water , you 've just created a mixture of soil and water -- mud . it turns out that macaroni salad is actually a mixture of mixtures because many of the ingredients , like mayo and mustard , are already mixtures themselves , which is nice for us because if we look closely , we 'll the see the three main types of mixtures that exist . the size of the particles in a mixture determines the type of mixture . on one end of the scale is a suspension , like our muddy water example . you get this if you take big chunks of something and mix it with something else so those chunks are just floating around . take runny mustard for example . you 'll see a bunch of little particles like mustard seeds , pepper , allspice , and minced shallots all floating around in a liquid , in this case vinegar with water . this is called a suspension because you 've got particles of one thing suspended in another . now , on the other end of the spectrum is a solution . the particles in this mixture are so small , they are the actual molecules . a solution is sort of like a suspension of molecules where one type of molecule is blended or dissolved with another . vinegar is an example of a solution where the molecules of acetic acid are blended with molecules of water . the chemical properties of the molecules have n't changed , they 're just evenly mixed together now . saltwater and carbonated soda are both examples of solutions where other molecules are dissolved in water . the last type of mixture is called a colloid , which is somewhere between a suspension and a solution . it 's when you take two materials that do n't dissolve and you make the particles so small that they ca n't separate . mayo is what happens when you take oil and water , which do n't mix , and you bind them together , usually with the help of another substance called an emulsifier . in the case of mayo , it 's lecithin , found in eggs . and now you are left with really small globs of oil hanging out with really small droplets of water . whipped cream , hairspray , styrofoam , and jello are all other examples of colloids . so , let 's get back to macaroni salad . you 've call colloids like mayo , suspensions like mustard , and solutions like vinegar , but you 've also got celery , shallots , and all other vegetable chunks that are also part of the salad . these are n't mixtures , really , but we can break them up , just like a tv can be broken up into smaller and smaller complex component parts . in the case of vegetables , if you keep breaking things up , they 'll eventually end with thousands of complex organic molecules , things like atp synthase and rna transcriptase and water . so now , once we 've unblended all the solutions , unmixed all the colloids , separated all the suspensions and taken apart all of our vegetables , we 've reached the end of what we can unmix physically . what we 're left with is a whole bunch of molecules , and these molecules remain chemically the same whether they are by themselves or thrown together in a salad . if you want to separate these guys even further , we need to unmix things chemically , which means we need to start breaking some bonds .

they 're still soil and water , you 've just created a mixture of soil and water -- mud . it turns out that macaroni salad is actually a mixture of mixtures because many of the ingredients , like mayo and mustard , are already mixtures themselves , which is nice for us because if we look closely , we 'll the see the three main types of mixtures that exist . the size of the particles in a mixture determines the type of mixture .

what are examples of other mixtures that you can break down physically ?

what is proof ? and why is it so important in mathematics ? proofs provide a solid foundation for mathematicians logicians , statisticians , economists , architects , engineers , and many others to build and test their theories on . and they 're just plain awesome ! let me start at the beginning . i 'll introduce you to a fellow named euclid . as in , `` here 's looking at you , clid . '' he lived in greece about 2,300 years ago , and he 's considered by many to be the father of geometry . so if you 've been wondering where to send your geometry fan mail , euclid of alexandria is the guy to thank for proofs . euclid is not really known for inventing or discovering a lot of mathematics but he revolutionized the way in which it is written , presented , and thought about . euclid set out to formalize mathematics by establishing the rules of the game . these rules of the game are called axioms . once you have the rules , euclid says you have to use them to prove what you think is true . if you ca n't , then your theorem or idea might be false . and if your theorem is false , then any theorems that come after it and use it might be false too . like how one misplaced beam can bring down the whole house . so that 's all that proofs are : using well-established rules to prove beyond a doubt that some theorem is true . then you use those theorems like blocks to build mathematics . let 's check out an example . say i want to prove that these two triangles are the same size and shape . in other words , they are congruent . well , one way to do that is to write a proof that shows that all three sides of one triangle are congruent to all three sides of the other triangle . so how do we prove it ? first , i 'll write down what we know . we know that point m is the midpoint of ab . we also know that sides ac and bc are already congruent . now let 's see . what does the midpoint tell us ? luckily , i know the definition of midpoint . it is basically the point in the middle . what this means is that am and bm are the same length , since m is the exact middle of ab . in other words , the bottom side of each of our triangles are congruent . i 'll put that as step two . great ! so far i have two pairs of sides that are congruent . the last one is easy . the third side of the left triangle is cm , and the third side of the right triangle is - well , also cm . they share the same side . of course it 's congruent to itself ! this is called the reflexive property . everything is congruent to itself . i 'll put this as step three . ta dah ! you 've just proven that all three sides of the left triangle are congruent to all three sides of the right triangle . plus , the two triangles are congruent because of the side-side-side congruence theorem for triangles . when finished with a proof , i like to do what euclid did . he marked the end of a proof with the letters qed . it 's latin for `` quod erat demonstrandum , '' which translates literally to `` what was to be proven . '' but i just think of it as `` look what i just did ! '' i can hear what you 're thinking : why should i study proofs ? one reason is that they could allow you to win any argument . abraham lincoln , one of our nation 's greatest leaders of all time used to keep a copy of euclid 's elements on his bedside table to keep his mind in shape . another reason is you can make a million dollars . you heard me . one million dollars . that 's the price that the clay mathematics institute in massachusetts is willing to pay anyone who proves one of the many unproven theories that it calls `` the millenium problems . '' a couple of these have been solved in the 90s and 2000s . but beyond money and arguments , proofs are everywhere . they underly architecture , art , computer programming , and internet security . if no one understood or could generate a proof , we could not advance these essential parts of our world . finally , we all know that the proof is in the pudding . and pudding is delicious . qed .

they share the same side . of course it 's congruent to itself ! this is called the reflexive property . everything is congruent to itself .

the property that anything is congruent to itself is called

in this short video , we 're going to show you how we used animation to make custom playing cards to do magical tricks in ted-ed 's lesson on synesthesia . synesthesia is a neurological condition in which two or more senses are paired together to create a completely new experience . for example , many synesthetes see letters and numbers in colors , even when they are printed in black . or they can taste certain words . for instance , jail tastes like bacon . because synesthesia generally involves the brain pairing up two or more senses , we paired up playing cards with unique , colorful , and visceral symbols . we then used an animation technique called stop motion to manipulate the cards in ways that would be otherwise physically impossible . and as the cards were flipping , shuffling , and sliding , we used a mixture of animation and reality to ensure that the symbols on the cards did their part to explain the nuances of synesthesia . this type of animation is very difficult to pull off without some planning first . a storyboard is a series of still images that basically serve as a road map for an animation from beginning to end . an animatic is a storyboard in motion . by making the animatic , we were able to review the digital motion for each shot , which allowed us to progressively work out timing , camera positioning , and , most importantly , any challenges we anticipated in the final animation process . how many hands do you need to shuffle a deck of cards ? here , we wanted to emphasize each nucleotide in the dna sequence and stop motion allows for more control . by shuffling between individual frames , we could ensure that each card had a controlled amount of screen time , in this case , three frames , and that the card 's placement was consistent . but sometimes four hands just is n't enough . we use this trick a lot in this lesson , all thanks to one secret ingredient : play-doh ! by molding the play-doh into different sized pyramids , the cards can be held in different positions , always keeping the pyramid big enough to support the card , but small enough to not be seen and to not cast its own revealing shadow . making an animated movie is like making a delicious layer cake . it 's up to the animators to create the many planes , or layers . the use of green screen enables us to shoot individual elements moving , and to later assemble those layers one on top of the other . using software , we key out the green color , both on the background and play-doh . layer the cards , add the hands , insert a background , and if you planned your ingredients carefully , everything should come together just right . so , grab some fishing wire , glue , masking tape , chopsticks , and whatever else you can find . we 'd love to see you make some of your own animated illusions .

in this short video , we 're going to show you how we used animation to make custom playing cards to do magical tricks in ted-ed 's lesson on synesthesia . synesthesia is a neurological condition in which two or more senses are paired together to create a completely new experience .

what is the special ingredient the animators used to make this lesson ?

it may sound like a paradox , or some cruel joke , but whatever it is , it 's true . beethoven , the composer of some of the most celebrated music in history , spent most of his career going deaf . so how was he still able to create such intricate and moving compositions ? the answer lies in the patterns hidden beneath the beautiful sounds . let 's take a look at the famous `` moonlight sonata , '' which opens with a slow , steady stream of notes grouped into triplets : one-and-a-two-and-a-three-and-a . but though they sound deceptively simple , each triplet contains an elegant melodic structure , revealing the fascinating relationship between music and math . beethoven once said , `` i always have a picture in my mind when composing and follow its lines . '' similarly , we can picture a standard piano octave consisting of thirteen keys , each separated by a half step . a standard major or minor scale uses eight of these keys , with five whole step intervals and two half step ones . and the first half of measure 50 , for example , consists of three notes in d major , separated by intervals called thirds , that skip over the next note in the scale . by stacking the scale 's first , third and fifth notes , d , f-sharp and a , we get a harmonic pattern known as a triad . but these are n't just arbitrary magic numbers . rather , they represent the mathematical relationship between the pitch frequencies of different notes which form a geometric series . if we begin with the note a3 at 220 hertz , the series can be expressed with this equation , where `` n '' corresponds to successive notes on the keyboard . the d major triplet from the moonlight sonata uses `` n '' values five , nine , and twelve . and by plugging these into the function , we can graph the sine wave for each note , allowing us to see the patterns that beethoven could not hear . when all three of the sine waves are graphed , they intersect at their starting point of 0,0 and again at 0,0.042 . within this span , the d goes through two full cycles , f-sharp through two and a half , and a goes through three . this pattern is known as consonance , which sounds naturally pleasant to our ears . but perhaps equally captivating is beethoven 's use of dissonance . take a look at measures 52 through 54 , which feature triplets containing the notes b and c. as their sine graphs show , the waves are largely out of sync , matching up rarely , if at all . and it is by contrasting this dissonance with the consonance of the d major triad in the preceding measures that beethoven adds the unquantifiable elements of emotion and creativity to the certainty of mathematics , creating what hector berlioz described as `` one of those poems that human language does not know how to qualify . '' so although we can investigate the underlying mathematical patterns of musical pieces , it is yet to be discovered why certain sequences of these patterns strike the hearts of listeners in certain ways . and beethoven 's true genius lay not only in his ability to see the patterns without hearing the music , but to feel their effect . as james sylvester wrote , `` may not music be described as the mathematics of the sense , mathematics as music of the reason ? '' the musician feels mathematics . the mathematician thinks music . music , the dream . mathematics , the working life .

as james sylvester wrote , `` may not music be described as the mathematics of the sense , mathematics as music of the reason ? '' the musician feels mathematics . the mathematician thinks music .

describe the chromatic scale on a piano keyboard and how it relates to patterns in mathematics .

one of the most amazing facts in physics is this : everything in the universe , from light to electrons to atoms , behaves like both a particle and a wave at the same time . all of the other weird stuff you might have heard about quantum physics , schrodinger 's cat , god playing dice , spooky action at a distance , all of it follows directly from the fact that everything has both particle and wave nature . this might sound crazy . if you look around , you 'll see waves in water and particles of rock , and they 're nothing alike . so why would you think to combine them ? physicists did n't just decide to mash these things together out of no where . rather , they were led to the dual nature of the universe through a process of small steps , fitting together lots of bits of evidence , like pieces in a puzzle . the first person to seriously suggest the dual nature of light was albert einstein in 1905 , but he was picking up an earlier idea from max planck . planck explained the colors of light emitted by hot objects , like the filament in a light bulb , but to do it , he needed a desperate trick : he said the object was made up of oscillators that could only emit light in discrete chunks , units of energy that depend on the frequency of the light . planck was never really happy with this , but einstein picked it up and ran with it . he applied planck 's idea to light itself , saying that light , which everybody knew was a wave , is really a stream of photons , each with a discrete amount of energy . einstein himself called this the only truly revolutionary thing he did , but it explains the way light shining on a metal surface knocks loose electrons . even people who hated the idea had to agree that it works brilliantly . the next puzzle piece came from ernest rutherford in england . in 1909 , ernest marsden and hans geiger , working for rutherford , shot alpha particles at gold atoms and were stunned to find that some bounced straight backwards . this showed that most of the mass of the atom is concentrated in a tiny nucleus . the cartoon atom you learn in grade school , with electrons orbiting like a miniature solar system , that 's rutherford 's . there 's one little problem with rutherford 's atom : it ca n't work . classical physics tells us that an electron whipping around in a circle emits light , and we use this all the time to generate radio waves and x-rays . rutherford 's atoms should spray x-rays in all directions for a brief instant before the electron spirals in to crash into the nucleus . but niels bohr , a danish theoretical physicist working with rutherford , pointed out that atoms obviously exist , so maybe the rules of physics needed to change . bohr proposed that an electron in certain special orbits does n't emit any light at all . atoms absorb and emit light only when electrons change orbits , and the frequency of the light depends on the energy difference in just the way planck and einstein introduced . bohr 's atom fixes rutherford 's problem and explains why atoms emit only very specific colors of light . each element has its own special orbits , and thus its own unique set of frequencies . the bohr model has one tiny problem : there 's no reason for those orbits to be special . but louis de broglie , a french phd student , brought everything full circle . he pointed out that if light , which everyone knew is a wave , behaves like a particle , maybe the electron , which everyone knew is a particle , behaves like a wave . and if electrons are waves , it 's easy to explain bohr 's rule for picking out the special orbits . once you have the idea that electrons behave like waves , you can go look for it . and within a few years , scientists in the us and uk had observed wave behavior from electrons . these days we have a wonderfully clear demonstration of this : shooting single electrons at a barrier with slits cut in it . each electron is detected at a specific place at a specific time , like a particle . but when you repeat the experiment many times , all the individual electrons trace out a pattern of stripes , characteristic of wave behavior . the idea that particles behave like waves , and vice versa , is one of the strangest and most powerful in physics . richard feynman famously said that this illustrates the central mystery of quantum mechanics . everything else follows from this , like pieces of a puzzle falling into place .

but when you repeat the experiment many times , all the individual electrons trace out a pattern of stripes , characteristic of wave behavior . the idea that particles behave like waves , and vice versa , is one of the strangest and most powerful in physics . richard feynman famously said that this illustrates the central mystery of quantum mechanics .

quantum mechanics tells us that everything in the universe has some characteristics of waves , and some characteristics of particles . can you think of any other examples ( in physics or another subject ) of things that turn out to be described not as purely one thing or another , but a mix of two different models ?

translator : tom carter reviewer : bedirhan cinar it 's march the 17th in a.d. 73 . we 're visiting ancient rome to watch the liberalia , an annual festival that celebrates the liberty of rome 's citizens . we 're looking in at a 17-year-old named lucius popidius secundus . he 's not from a poor family , but he lives in the region known as the subura , a poorer neighborhood in rome , yet close to the center of the city . ( gong ) the tenants of these apartments are crammed in , ( grunting ) which poses considerable risk . fires are frequent and the smell of ash and smoke in the morning is not uncommon . lucius , who awoke at dawn , has family duties to perform today . ( cheering ) his 15-year-old brother is coming of age . half the children in ancient rome die before they reach adulthood , so this is a particularly important milestone . lucius watches his brother stand in his new toga before the household shrine with its protective deities , as he places his bulla , a protective amulet , in the shrine with a prayer of thanks . the bulla had worked . it had protected him . unlike many others , he had survived to become an adult . at 17 , lucius has almost completed his education . he has learned to speak well , make public speeches , and how to read and write both latin and greek . his father has taught him the types of things you ca n't learn in the classroom : how to run , how to swim , and how to fight . lucius could choose , at 17 , to become a military tribune and command soldiers on the edge of the empire . but in other ways , lucius is still a child . he 's not trusted to arrange business deals . his father will take care of that until he is 25 . and dad will arrange lucius ' marriage to a girl 10 years younger . his dad has his eye on a family with a 7-year-old daughter . back to the liberalia . as lucius leaves with his family , the shops are open as the population goes about its business . the streets are full of itinerant traders selling trinkets and people bustling from place to place . large wagons are not allowed in the city until after the ninth hour but the streets are still crowded . fathers and uncles take the kids to the forum augustus to see statues of rome 's famous warriors like aeneas , who led rome 's ancestors , the trojans , to italy . and romulus , rome 's founder . and all the great generals of the republic from more than 100 years earlier . lovingly , we can imagine fathers and guardians with their now adult children remembering stories of rome 's glory and re-telling the good deeds and sayings of the great men of the past : lessons on how to live well , and to overcome the follies of youth . there is a sense of history in this place , relevant to their present . romans made an empire without end in time and space . ( thump ) rome was destined to be eternal through warfare . wars were a fact of life , even in a.d. 73 . there are campaigns in the north of england and into scotland , to the north of the river danube into romania , and on the frontier between syria and iraq to the east . it 's now the eighth hour -- time to head for the baths . lucius and his family head up the via lata , the wide street , to the campus martius , and the enormous baths of agrippa . the family members leave the clients and freedmen outside , and enter the baths with their peer group . baths would change from dark , steamy rooms to light ones . the romans had perfected window glass . everyone moves from the cold room to the tepid room and to the very hot room . ( man ) oops ! more than an hour later , the bathers leave massaged , oiled , ( whistling ) and have been scraped down with a strigil to remove the remaining dirt . at the ninth hour , seven hours after they left home , the men return for a celebratory dinner . dinner is an intimate affair , with nine people reclining around the low table . slaves attend to their every need if the diners , through gestures , demand more food and wine . as the day closes , we can hear the rumble of wagons outside . the clients and freedmen , with a meal of robust -- if inferior -- food inside them , shuffle off to the now tepid baths before returning to their apartment blocks . back at lucius ' house , the drinking continues into the night . lucius and his stepbrother do n't look too well . a slave stands by in case either of them needs to vomit . with hindsight , we know lucius ' future . in 20 years ' time , the emperor vespasian 's youngest son , domitian , as emperor , will enact a reign of terror . will lucius survive ? ( drums )

there are campaigns in the north of england and into scotland , to the north of the river danube into romania , and on the frontier between syria and iraq to the east . it 's now the eighth hour -- time to head for the baths . lucius and his family head up the via lata , the wide street , to the campus martius , and the enormous baths of agrippa .

at the baths , bathers participate in a more-than-an-hour long event that includes all of the following except :

so actinium : it ’ s often said about radioactivity that you might be glowing in the dark if you work with radioactive elements . by-and-large it ’ s not true . however , actinium is one of them which might do that because the element itself glows blue in the dark . and actinium is actually more dangerous than plutonium , and plutonium was once described as the most deadly and toxic substance known to man . so it ’ s pretty dangerous . i ’ ll avoid it ! have you had anything to do with it at all ? no , because it ’ s so dangerous . when i was an undergraduate i saw this book here , which was written by seaborg , and i really liked the cover because i think it looked really nice and i was also quite interested about the transuranium elements because i didn ’ t really know much about them . and he , probably more than anybody else , discovered more of these elements than any other scientist , probably more elements than most if not all scientists . and he wrote in this book about the chemistry of the different elements and , although we consider that these are pretty radioactive and so on , they at least managed to isolate enough material so you could see it in the bottom of a small glass tube . it may not have been bigger than the tip of a pin or something like that , but it ’ s a huge amount compared to the one or two atoms that were formed of some of these elements very near the end of the periodic table .

by-and-large it ’ s not true . however , actinium is one of them which might do that because the element itself glows blue in the dark . and actinium is actually more dangerous than plutonium , and plutonium was once described as the most deadly and toxic substance known to man .

actinium glows in the dark , but with which color ?

every day of your life , you move through systems of power that other people made . do you sense them ? do you understand power ? do you realize why it matters ? power is something we are often uncomfortable talking about . that 's especially true in civic life , how we live together in community . in a democracy , power is supposed to reside with the people , period . any further talk about power and who really has it seems a little dirty , maybe even evil . but power is no more inherently good or evil than fire or physics . it just is . it governs how any form of government works . it determines who gets to determine the rules of the game . so learning how power operates is key to being effective , being taken seriously , and not being taken advantage of . in this lesson , we 'll look at where power comes from , how it 's exercised and what you can do to become more powerful in public life . let 's start with a basic definition . power is the ability to make others do what you would have them do . of course , this plays out in all arenas of life , from family to the workplace to our relationships . our focus is on the civic arena , where power means getting a community to make the choices and to take the actions that you want . there are six main sources of civic power . first , there 's physical force and a capacity for violence . control of the means of force , whether in the police or a militia , is power at its most primal . a second core source of power is wealth . money creates the ability to buy results and to buy almost any other kind of power . the third form of power is state action , government . this is the use of law and bureaucracy to compel people to do or not do certain things . in a democracy , for example , we the people , theoretically , give government its power through elections . in a dictatorship , state power emerges from the threat of force , not the consent of the governed . the fourth type of power is social norms or what other people think is okay . norms do n't have the centralized machinery of government . they operate in a softer way , peer to peer . they can certainly make people change behavior and even change laws . think about how norms around marriage equality today are evolving . the fifth form of power is ideas . an idea , individual liberties , say , or racial equality , can generate boundless amounts of power if it motivates enough people to change their thinking and actions . and so the sixth source of power is numbers , lots of humans . a vocal mass of people creates power by expressing collective intensity of interest and by asserting legitimacy . think of the arab spring or the rise of the tea party . crowds count . these are the six main sources of power , what power is . so now , let 's think about how power operates . there are three laws of power worth examining . law number one : power is never static . it 's always either accumulating or decaying in a civic arena . so if you are n't taking action , you 're being acted upon . law number two : power is like water . it flows like a current through everyday life . politics is the work of harnessing that flow in a direction you prefer . policymaking is an effort to freeze and perpetuate a particular flow of power . policy is power frozen . law number three : power compounds . power begets more power , and so does powerlessness . the only thing that keeps law number three from leading to a situation where only one person has all the power is how we apply laws one and two . what rules do we set up so that a few people do n't accumulate too much power , and so that they ca n't enshrine their privilege in policy ? that 's the question of democracy , and you can see each of these laws at work in any news story . low wage workers organize to get higher pay . oil companies push to get a big pipeline approved . gay and lesbian couples seek the legal right to marry . urban parents demand school vouchers . you may support these efforts or not . whether you get what you want depends on how adept you are with power , which brings us finally to what you can do to become more powerful in public life . here , it 's useful to think in terms of literacy . your challenge is to learn how to read power and write power . to read power means to pay attention to as many texts of power as you can . i do n't mean books only . i mean seeing society as a set of texts . do n't like how things are in your campus or city or country ? map out who has what kind of power , arrayed in what systems . understand why it turned out this way , who 's made it so , and who wants to keep it so . study the strategies others in such situations used : frontal attack or indirection , coalitions or charismatic authority . read so you may write . to write power requires first that you believe you have the right to write , to be an author of change . you do . as with any kind of writing , you learn to express yourself , speak up in a voice that 's authentic . organize your ideas , then organize other people . practice consensus building . practice conflict . as with writing , it 's all about practice . every day you have a chance to practice , in your neighborhood and beyond . set objectives , then bigger ones . watch the patterns , see what works . adapt , repeat . this is citizenship . in this short lesson , we 've explored where civic power comes from , how it works and what you can do to exercise it . one big question remaining is the `` why '' of power . do you want power to benefit everyone or only you ? are your purposes pro-social or anti-social ? this question is n't about strategy . it 's about character , and that 's another set of lessons . but remember this : power plus character equals a great citizen , and you have the power to be one .

you do . as with any kind of writing , you learn to express yourself , speak up in a voice that 's authentic . organize your ideas , then organize other people . practice consensus building . practice conflict . as with writing , it 's all about practice .

speaking up in an authentic voice , organizing your ideas and people , practicing consensus and conflict skills , and adapting are all part of _____ .

on october 4 , 1957 , the world watched in awe and fear as the soviet union launched sputnik , the world 's first man-made satellite , into space . this little metal ball , smaller than two feet in diameter , launched a space race between the u.s. and u.s.s.r. that would last for eighteen years and change the world as we know it . sputnik was actually not the first piece of human technology to enter space . that superlative goes to the v-2 rocket used by germany in missile attacks against allied cities as a last-ditch effort in the final years of world war ii . it was n't very effective , but , at the end of the war , both the u.s. and u.s.s.r. had captured the technology and the scientists that had developed it and began using them for their own projects . and by august 1957 , the soviet 's successfully tested the first intercontinental ballistic missile , the r-7 , the same rocket that would be used to launch sputnik two months later . so , the scary thing about sputnik was not the orbiting ball itself , but the fact that the same technology could be used to launch a nuclear warhead at any city . not wanting to fall too far behind , president eisenhower ordered the navy to speed up its own project and launch a satellite as soon as possible . so , on december 6 , 1957 , excited people across the nation tuned in to watch the live broadcast as the vanguard tv3 satellite took off and crashed to the ground two seconds later . the vanguard failure was a huge embarassment for the united states . newspapers printed headlines like , `` flopnik '' and `` kaputnik . '' and a soviet delegate at the u.n. mockingly suggested that the u.s. should receive foreign aid for developing nations . fortunately , the army had been working on their own parallel project , the explorer , which was successfully launched in january 1958 , but the u.s. had barely managed to catch up before they were surpassed again as yuri gargarin became the first man in space in april 1961 . almost a year passed and several more soviet astronauts completed their missions before project mercury succeeded in making john glenn the first american in orbit in february 1962 . by this time , president kennedy had realized that simply catching up to each soviet advance a few months later was n't going to cut it . the u.s. had to do something first , and in may 1961 , a month after gargarin 's flight , he announced the goal of putting a man on the moon by the end of the 1960s . they succeeded in this through the apollo program with neil armstrong taking his famous step on july 20 , 1969 . with both countries ' next turning their attention to orbital space stations , there 's no telling how much longer the space race could have gone on . but because of improving relations negotiated by soviet premier leonid breshnev and u.s. president nixon , the u.s.s.r. and u.s. moved toward cooperation rather than competition . the successful joint mission , known as apollo-soyuz , in which an american apollo spacecraft docked with a soviet soyuz craft and the two crews met , shook hands , and exchanged gifts , marked the end of the space race in 1975 . so , in the end , what was the point of this whole space race ? was it just a massive waste of time ? two major superpowers trying to outdo each other by pursuing symbolic projects that were both dangerous and expensive , using resources that could have been better spent elsewhere ? well , sure , sort of , but the biggest benefits of the space program had nothing to do with one country beating another . during the space race , funding for research and education , in general , increased dramatically , leading to many advances that may not have otherwise been made . many nasa technologies developed for space are now widely used in civilian life , from memory foam in mattresses to freeze-dried food , to leds in cancer treatment . and , of course , the satellites that we rely on for our gps and mobile phone signals would not have been there without the space program . all of which goes to show that the rewards of scientific research and advancement are often far more vast than even the people pursuing them can imagine .

sputnik was actually not the first piece of human technology to enter space . that superlative goes to the v-2 rocket used by germany in missile attacks against allied cities as a last-ditch effort in the final years of world war ii . it was n't very effective , but , at the end of the war , both the u.s. and u.s.s.r. had captured the technology and the scientists that had developed it and began using them for their own projects .

what materials do you need to construct a rocket ? describe why you need these materials .

sunken relics , ghostly shipwrecks , and lost cities . these are n't just wonders found in fictional adventures . beneath the ocean 's surface , there are ruins where people once roamed and shipwrecks loaded with artifacts from another time . this is the domain of underwater archaeology , where researchers discover and study human artifacts that slipped into the sea . they 're not on a treasure hunt . underwater archaeology reveals important information about ancient climates and coastlines , it tells us how humans sailed the seas , and what life was like millennia ago . so what exactly can we find ? at shallow depths mingled in with modern-day items , we 've discovered all sorts of ancient artifacts . this zone contains evidence of how our ancestors fished , how they repaired their ships , disposed of their trash , and even their convicted pirates , who were buried below the tide line . and it 's not just our recent history . 800,000-year old footprints were found along the shore in norfolk , britain . in these shallow depths , the remains of sunken cities also loom up from the sea floor , deposited there by earthquakes , tsunamis , and earth 's sinking plates . almost every sunken city can be found at these shallow depths because the sea level has changed little in the several thousand years that city-building civilizations have existed . for instance , in shallow waters off the coast of italy lies baia , a roman seaside town over 2,000 years old . there , it 's possible to swim among the ruins of structures built by rome 's great families , senators , and emperors . and then there are shipwrecks . as ships grow too old for use , they 're usually abandoned near shore in out-of-the-way places like estuaries , rivers , and shallow bays . archaeologists use these like a timeline to map a harbor 's peaks and declines , and to get clues about the historic art of shipbuiding . at roskilde in denmark , for example , five purposefully sunken vessels reveal how vikings crafted their fearsome long ships 1,000 years ago . when we descend a bit further , we reach the zone where the deepest human structures lie , like ancient harbor walls and quays . we also see more shipwrecks sunk by storms , war , and collisions . we 're still excavating many of these wrecks today , like blackbeard 's ship , which is revealing secrets about life as an 18th century pirate . but past 50 feet , there are even deeper , better preserved shipwrecks , like the wreck at antikythera , which sank during the 1st century bc . when it was discovered , it contained statues , trade cargo , and also the earliest known computer , a mysterious device called the antikythera mechanism that kept track of astronomical changes and eclipses . today , it gives archaeologists vital information about the knowledge possessed by the ancient greeks . it is in this zone that we also begin to find aircraft and submarines , such as those from the world wars . plunging as deep as 200 feet , we can find some of the earliest and rarest signs of human history . prior to 5,000 years ago , there was a lot more dry land because glaciers trapped much of the water that now forms the sea . our ancestors spread across these lands , and so on the sea floor , we find their camps , stone tools , and the bones of animals they hunted . these sites give us invaluable knowledge about our ancestor 's migration patterns , hunting methods , and technologies . in the deepest zone , no human has ever walked . this area has been submerged since well before mankind evolved . the only artifacts we find are those that have drifted down from above , like nasa 's saturn v rocket engines at 14,000 feet , and the deepest shipwrecks . the ocean is like a huge underwater museum that constantly adds to our knowledge about humanity . with only a fraction of it explored , discoveries are sure to continue long into the future .

we 're still excavating many of these wrecks today , like blackbeard 's ship , which is revealing secrets about life as an 18th century pirate . but past 50 feet , there are even deeper , better preserved shipwrecks , like the wreck at antikythera , which sank during the 1st century bc . when it was discovered , it contained statues , trade cargo , and also the earliest known computer , a mysterious device called the antikythera mechanism that kept track of astronomical changes and eclipses .

what is the benefit of shipwrecks deeper than 50 feet to understanding the past , as opposed to those in shallow waters ?

translator : andrea mcdonough reviewer : bedirhan cinar at birth , our bodies are roughly 75 % water . we remain mostly water for the rest of our lives . we can not survive even a week without fresh water . there 's no life without it for ecosystems , societies , and individuals . so , how much usable water is there on earth ? most of the water on earth is ocean , a salty 97.5 % , to be precise , and the remaining 2.5 % is fresh water . that little sliver of liquid sustains human life on earth , it literally holds up civilizations . 2.5 % is a small proportion to be sure , and even that is broken down into smaller parts : surface water , water in ice caps and polar regions , and ground water . first , surface water . all the liquid water above ground is surface water and it is a tiny blip of an amount . 0.3 % of all fresh water is surface water . it may seem counterintuitive , but it accounts for little streams all over the planet . all rivers , including the nile , the jordan , and the mississippi , and lakes , large to small , like victoria , the great lakes , and baikal . second , ice caps and polar regions freeze up to 70 % of the planet 's fresh water . this water is significant , but it is n't available for human use in a regular way . finally , nearly 30 % of all water on earth is ground water . as the name suggests , that 's water in the ground . it can rest still and deep in huge caverns , or it can snuggle in the little crevices of rock and pebble . the upshot - thank goodness for ground water ! it 's invisible to us , but it is much more plentiful than surface water . it is much more reliable and easier to obtain than frozen water . without ground water , our societies would be parched . so , how are we using that water ? as a result of industrialization and population growth , demand for fresh water skyrocketed in the last century . where is all that water going ? first , we have to remember that fresh water is a global concern , but it is always local . context matters . the sahara is not seattle . still , some general information can help us get a handle on major trends . who consumes the most fresh water ? and , what sectors consume the most fresh water ? first , who . well , the united states consumes the most water per capita of any country in the entire world , followed by parts of europe and large industrializing nations like china . but , this does n't tell us what water is being used for . so let 's look at it another way . if we ask what kinds of uses water is going towards , we see a different picture . agriculture accounts for roughly 70 % of global fresh water consumption . again , remember the numbers vary by region , but still , it 's a staggering amount . and , this makes a certain kind of sense : we need to eat , we need water to grow food ; the bigger the population , the more food we need ; and , the wealthier we get , the more meat we eat , and the more water is required to produce our food . furthermore , 22 % of all fresh water worldwide goes to industrial uses . this includes the production of electricity , the extraction of fossil fuels , and the manufacturing of all manner of goods , from microchips , to paper , to blimps . 70 % to agriculture , 22 % to industrial uses , what 's left ? 8 % all those domestic uses - cooking , cleaning , bathing , drinking - it 's a drop in the bucket of overall water use .

without ground water , our societies would be parched . so , how are we using that water ? as a result of industrialization and population growth , demand for fresh water skyrocketed in the last century . where is all that water going ?

list three factors that increase demand for fresh water . give examples of how we are meeting that demand .

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 )

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 .

in 1845 , how did americans travel ?

picture warm , gooey cookies , crunchy candies , velvety cakes , waffle cones piled high with ice cream . is your mouth watering ? are you craving dessert ? why ? what happens in the brain that makes sugary foods so hard to resist ? sugar is a general term used to describe a class of molecules called carbohydrates , and it 's found in a wide variety of food and drink . just check the labels on sweet products you buy . glucose , fructose , sucrose , maltose , lactose , dextrose , and starch are all forms of sugar . so are high-fructose corn syrup , fruit juice , raw sugar , and honey . and sugar is n't just in candies and desserts , it 's also added to tomato sauce , yogurt , dried fruit , flavored waters , or granola bars . since sugar is everywhere , it 's important to understand how it affects the brain . what happens when sugar hits your tongue ? and does eating a little bit of sugar make you crave more ? you take a bite of cereal . the sugars it contains activate the sweet-taste receptors , part of the taste buds on the tongue . these receptors send a signal up to the brain stem , and from there , it forks off into many areas of the forebrain , one of which is the cerebral cortex . different sections of the cerebral cortex process different tastes : bitter , salty , umami , and , in our case , sweet . from here , the signal activates the brain 's reward system . this reward system is a series of electrical and chemical pathways across several different regions of the brain . it 's a complicated network , but it helps answer a single , subconscious question : should i do that again ? that warm , fuzzy feeling you get when you taste grandma 's chocolate cake ? that 's your reward system saying , `` mmm , yes ! '' and it 's not just activated by food . socializing , sexual behavior , and drugs are just a few examples of things and experiences that also activate the reward system . but overactivating this reward system kickstarts a series of unfortunate events : loss of control , craving , and increased tolerance to sugar . let 's get back to our bite of cereal . it travels down into your stomach and eventually into your gut . and guess what ? there are sugar receptors here , too . they are not taste buds , but they do send signals telling your brain that you 're full or that your body should produce more insulin to deal with the extra sugar you 're eating . the major currency of our reward system is dopamine , an important chemical or neurotransmitter . there are many dopamine receptors in the forebrain , but they 're not evenly distributed . certain areas contain dense clusters of receptors , and these dopamine hot spots are a part of our reward system . drugs like alcohol , nicotine , or heroin send dopamine into overdrive , leading some people to constantly seek that high , in other words , to be addicted . sugar also causes dopamine to be released , though not as violently as drugs . and sugar is rare among dopamine-inducing foods . broccoli , for example , has no effect , which probably explains why it 's so hard to get kids to eat their veggies . speaking of healthy foods , let 's say you 're hungry and decide to eat a balanced meal . you do , and dopamine levels spike in the reward system hot spots . but if you eat that same dish many days in a row , dopamine levels will spike less and less , eventually leveling out . that 's because when it comes to food , the brain evolved to pay special attention to new or different tastes . why ? two reasons : first , to detect food that 's gone bad . and second , because the more variety we have in our diet , the more likely we are to get all the nutrients we need . to keep that variety up , we need to be able to recognize a new food , and more importantly , we need to want to keep eating new foods . and that 's why the dopamine levels off when a food becomes boring . now , back to that meal . what happens if in place of the healthy , balanced dish , you eat sugar-rich food instead ? if you rarely eat sugar or do n't eat much at a time , the effect is similar to that of the balanced meal . but if you eat too much , the dopamine response does not level out . in other words , eating lots of sugar will continue to feel rewarding . in this way , sugar behaves a little bit like a drug . it 's one reason people seem to be hooked on sugary foods . so , think back to all those different kinds of sugar . each one is unique , but every time any sugar is consumed , it kickstarts a domino effect in the brain that sparks a rewarding feeling . too much , too often , and things can go into overdrive . so , yes , overconsumption of sugar can have addictive effects on the brain , but a wedge of cake once in a while wo n't hurt you .

and sugar is n't just in candies and desserts , it 's also added to tomato sauce , yogurt , dried fruit , flavored waters , or granola bars . since sugar is everywhere , it 's important to understand how it affects the brain . what happens when sugar hits your tongue ?

what important chemical in the brain is changed in response to sugar ingestion ?

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 .

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 .

seasonal change is a result of :

conventional wisdom about diets , including government health recommendations , seems to change all the time . and yet , ads routinely come about claiming to have the answer about what we should eat . so how do we distinguish what 's actually healthy from what advertisers just want us to believe is good for us ? marketing takes advantage of the desire to drop weight fast , and be stronger , slimmer , and brighter . and in the big picture , diet plans promising dramatic results , known as fad diets , are just what they seem : too good to be true . so where do diet fads even come from ? while the ancient greeks and romans rallied behind large-scale health regimens centuries earlier , this phenomenon began in earnest in the victorian era with crazes like the vinegar diet and the banting diet . since then , diets have advised us all sorts of things : to excessively chew , to not chew at all , to swallow a grapefruit per meal , non-stop cabbage soup , even consumption of arsenic , or tapeworms . if the idea of diet crazes has withstood history , could this mean that they work ? in the short term , the answer is often yes . low-carbohydrate plans , like the popular atkins or south beach diets , have an initial diuretic effect . sodium is lost until the body can balance itself out , and temporary fluid weight loss may occur . with other high-protein diets , you might lose weight at first since by restricting your food choices , you are dropping your overall calorie intake . but your body then lowers its metabolic rate to adjust to the shift , lessening the diet 's effect over time and resulting in a quick reversal if the diet is abandoned . so while these diets may be alluring early on , they do n't guarantee long-term benefits for your health and weight . a few simple guidelines , though , can help differentiate between a diet that is beneficial in maintaining long-term health , and one that only offers temporary weight changes . here 's the first tipoff : if a diet focuses on intensely cutting back calories or on cutting out entire food groups , like fat , sugar , or carbohydrates , chances are it 's a fad diet . and another red flag is ritual , when the diet in question instructs you to only eat specific foods , prescribed combinations , or to opt for particular food substitutes , like drinks , bars , or powders . the truth is shedding pounds in the long run simply does n't have a quick-fix solution . not all diet crazes tout weight loss . what about claims of superfoods , cleanses , and other body-boosting solutions ? marketing emphasizes the allure of products associated with ancient and remote cultures to create a sense of mysticism for consumers . while so-called superfoods , like blueberries or açaí , do add a powerful punch of nutrients , their super transformative qualities are largely exaggeration . they are healthy additions to a balanced diet , yet often , they 're marketed as part of sugary drinks or cereals , in which case the negative properties outweight the benefits . cleanses , too , may be great in moderation since they can assist with jumpstarting weight loss and can increase the number of fresh fruits and vegetables consumed daily . scientifically speaking , though , they 've not yet been shown to have either a long-term benefit or to detox the body any better than the natural mechanisms already in place . everywhere we look , we 're offered solutions to how we can look better , feel fitter , and generally get ahead . food is no exception , but advice on what we should eat is best left to the doctors and nutritionists who are aware of our individual circumstances . diets and food fads are n't inherently wrong . circumstantially , they might even be right , just not for everyone all of the time .

a few simple guidelines , though , can help differentiate between a diet that is beneficial in maintaining long-term health , and one that only offers temporary weight changes . here 's the first tipoff : if a diet focuses on intensely cutting back calories or on cutting out entire food groups , like fat , sugar , or carbohydrates , chances are it 's a fad diet . and another red flag is ritual , when the diet in question instructs you to only eat specific foods , prescribed combinations , or to opt for particular food substitutes , like drinks , bars , or powders .

give an example of a fad diet . what characteristic ( s ) of this diet let us know that it is a fad diet ?

translator : joseph geni reviewer : morton bast growing up in taiwan as the daughter of a calligrapher , one of my most treasured memories was my mother showing me the beauty , the shape and the form of chinese characters . ever since then , i was fascinated by this incredible language . but to an outsider , it seems to be as impenetrable as the great wall of china . over the past few years , i 've been wondering if i can break down this wall , so anyone who wants to understand and appreciate the beauty of this sophisticated language could do so . i started thinking about how a new , fast method of learning chinese might be useful . since the age of five , i started to learn how to draw every single stroke for each character in the correct sequence . i learned new characters every day during the course of the next 15 years . since we only have five minutes , it 's better that we have a fast and simpler way . a chinese scholar would understand 20,000 characters . you only need 1,000 to understand the basic literacy . the top 200 will allow you to comprehend 40 percent of basic literature -- enough to read road signs , restaurant menus , to understand the basic idea of the web pages or the newspapers . today i 'm going to start with eight to show you how the method works . you are ready ? open your mouth as wide as possible until it 's square . you get a mouth . this is a person going for a walk . person . if the shape of the fire is a person with two arms on both sides , as if she was yelling frantically , `` help ! i 'm on fire ! '' -- this symbol actually is originally from the shape of the flame , but i like to think that way . whichever works for you . this is a tree . tree . this is a mountain . the sun . the moon . the symbol of the door looks like a pair of saloon doors in the wild west . i call these eight characters radicals . they are the building blocks for you to create lots more characters . a person . if someone walks behind , that is `` to follow . '' as the old saying goes , two is company , three is a crowd . if a person stretched their arms wide , this person is saying , `` it was this big . '' the person inside the mouth , the person is trapped . he 's a prisoner , just like jonah inside the whale . one tree is a tree . two trees together , we have the woods . three trees together , we create the forest . put a plank underneath the tree , we have the foundation . put a mouth on the top of the tree , that 's `` idiot . '' ( laughter ) easy to remember , since a talking tree is pretty idiotic . remember fire ? two fires together , i get really hot . three fires together , that 's a lot of flames . set the fire underneath the two trees , it 's burning . for us , the sun is the source of prosperity . two suns together , prosperous . three together , that 's sparkles . put the sun and the moon shining together , it 's brightness . it also means tomorrow , after a day and a night . the sun is coming up above the horizon . sunrise . a door . put a plank inside the door , it 's a door bolt . put a mouth inside the door , asking questions . knock knock . is anyone home ? this person is sneaking out of a door , escaping , evading . on the left , we have a woman . two women together , they have an argument . ( laughter ) three women together , be careful , it 's adultery . so we have gone through almost 30 characters . by using this method , the first eight radicals will allow you to build 32 . the next group of eight characters will build an extra 32 . so with very little effort , you will be able to learn a couple hundred characters , which is the same as a chinese eight-year-old . so after we know the characters , we start building phrases . for example , the mountain and the fire together , we have fire mountain . it 's a volcano . we know japan is the land of the rising sun . this is a sun placed with the origin , because japan lies to the east of china . so a sun , origin together , we build japan . a person behind japan , what do we get ? a japanese person . the character on the left is two mountains stacked on top of each other . in ancient china , that means in exile , because chinese emperors , they put their political enemies in exile beyond mountains . nowadays , exile has turned into getting out . a mouth which tells you where to get out is an exit . this is a slide to remind me that i should stop talking and get off of the stage . thank you . ( applause )

so we have gone through almost 30 characters . by using this method , the first eight radicals will allow you to build 32 . the next group of eight characters will build an extra 32 . so with very little effort , you will be able to learn a couple hundred characters , which is the same as a chinese eight-year-old .

the first eight radicals will allow you to build how many characters ?

ok , so we take the top off . we add a match . the barking dog experiment was one of the most famous experiments and favourite experiments that was done by my former colleague , colonel b.d . shaw . so neil and i are preparing for one of my favourite reactions . itís called the barking dog reaction . this is a reaction which actually makes an element and weíre going to make some sulphur today . so the reactionís quite cool . in the barking dog experiment you have a mixture of the molecule carbon disulphide , cs2 . itís just like carbon dioxide butöwait a minute iímö so this is a test tube , a rather large test tube , of laughing gas , n2o , and weíre going to use this to make some sulphur . so i have a model here . so itís cs2 which has a carbon in the middle and sulphurs at either end . so it looks just like , in a model , as a molecule of co2 , but it has sulphur there and there . and this molecule , cs2 , will react with laughing gas , n2o . so where are we going to do this now ? in the dark somewhere . so essentially you are just using the laughing gas as a sort of oxygen to burn this molecule . what we are actually going to do is generate a lot of light . it used to be used as a flash , for cameras and for photography . what happens is you get a very bright emission of a sort of bluish purple light , which in the old days was used for taking photographs before people had flash-lamps on their cameras . they would set this off and it would give a great flash of light which could be used to take photographs . but because itís much slower than a flash it makes people really have quite a surprised look and this may well be why , in old photographs , people look so surprised because `` my god , this thing has gone off , whoosh ! '' so weíre on the hunt for a very dark place . in the tube , as the reaction takes place it generates heat . ok , so into the small lecture theatre which is vacant now . itís quite nice because we can turn all the lights off and make it a bit darker and see this reaction in its , sort of , best . so weíve managed to create a darker environment so we can really see the benefits from this chemistry , and neilís put some water in the bottom of the tube . and weíre going to put about 6-8 millilitres of carbon disulphide into this tube , and a good mix so you can be sure that we get all of that carbon disulphide going into the later phase so that itíll react really quite quickly with all of that oxygen , the n2o . as the flame goes down the tube it accelerates because the reactionís going faster and faster so it gives this great sort of ëwhoopí noise . now then , that was a really , really energetic reaction because the organic and the oxygen were all in the same phase and the reaction got a lot faster . the noise it made got a lot louder as it went down because of pressure . so what you can see in the tube here is actually the result or the aim of our chemical reaction today because we wanted to make some sulphur . so what weíve got here , coated on the inside of this tube , is a thin layer of polymeric sulphur . so you can see all this really quite nice sulphur coating the inside of the glass flask itself . now iím really fortunate because iím just going to go back to my office and prepare a lecture and leave neil to clean this . thanks . what are you doing mate ? well iíve just filled up my vessel with some oxygen . so this is liquid oxygen which we made for an earlier demonstration , and weíve just used it to drive off all of the non-combustible nitrogen form inside this glass vessel . well look at all that oxygen floating around inside the bottom of that flask , thatís really cool . all oscillating - a really nice experiment . yeah this is a really quite crazy jar . itís a small amount of sulphur , or ësuphurí , that weíve decanted out and unfortunately when we decanted it out we spelt the name wrong soö whoís responsible for that ? err , itís aövery old friend of mine and i couldnít possiblyögive you his identity as he would be really , really angry . wouldnít he , neil ? yeah iím saying nothing . and it wasnít neil . it wasnít me . so here weíve got a small amount of sulphur that we are going to put on the tip of this spoon . so you can see itís starting to melt . now with the top , so itís on fire and then weíll just drop it into the flask . and you can see that that sulphurís burning really intensely now , with a really quite beautiful flame . itís generating a lot of so2 , really smelly , which is why we are doing it inside this fume cupboard and you can see this really rich intense blue flame as that sulphur is burning in that excess oxygen in that atmosphere . ok so this is actually a sort of geological sample of sulphur . so you can see itís actually on the bottom , weíve actually got a rock and the sulphur crystals have actually formed on top of it . so actually , sulphur does occur naturally . i think itís been known since ancient times so , you know , when sermons are being delivered , fire and brimstone , was because hell is supposed to smell like sulphur , which is brimstone . but actually sulphur itself doesnít actually smell , but what you are smelling , the ësulphuryí smell , is actually oxidised material and hydrogen sulphide . well itís actually a mixture of sulphur and sand that was picked up by one of my colleagues on his honeymoon , though you see he was actually thinking about chemistry even on his honeymoon , though i donít think he told his wife that . i have a feeling but i could wrong that i bought this sample in oxfordshire where i used to live and i think itís actually from brazil , though i could be wrong . so as we are using up all the sulphur now the flame will die down until eventually it will go out . cool , there you go .

they would set this off and it would give a great flash of light which could be used to take photographs . but because itís much slower than a flash it makes people really have quite a surprised look and this may well be why , in old photographs , people look so surprised because `` my god , this thing has gone off , whoosh ! '' so weíre on the hunt for a very dark place .

have you ever seen a very old photograph where the people have a surprised look ? the professor explained the reason . can you remember it ?

sharks have been celebrated as powerful gods by some native cultures . for example , fijians believe the shark god dakuwaqa , could protect fisherman from the dangers at sea . and today , sharks are recognized as apex predators of the world 's ocean and include some of the earth 's longest living vertebrates . what is it that makes these fish worthy of our ancient legends and so successful in the seas ? much of their hunting prowess stems from a unique set of biological traits honed for more than 400 million years . their cartilaginous skeletons are less dense than bony ones and require less energy to move . large oily livers lend buoyancy to their streamlined bodies , and while trunk muscles of bony fishes attach directly to their skeletons , those of sharks also join to their skin . this special design transforms them into pressurized tubes whose springy skin can efficiently transmit muscular forces to the tail . shark skin has additional remarkable features . despite its smooth external appearance , at the micro level , it has a coarse texture thanks to thousands of tiny teeth-like scales called dermal denticles . each denticle is coated in a substance called enameloid , which turns the skin into a tough shield . plus the structure of denticles varies across the body in such a way as to reduce noise and drag when the shark moves through water . as for the teeth in their mouths , sharks can produce up to 50,000 in a lifetime . on average , they can lose one tooth a week , and each time that happens , it 's rapidly replaced . thanks to a layer of fluoride coating their teeth , sharks also avoid cavities . but teeth are n't the same in all sharks . they can vary across species and by diet . some are dense and flattened , useful for crushing mollusks . others are needle-like for gripping fish . the mouths of great whites contain pointy lower teeth for holding prey and triangular serrated upper teeth for slicing . this variety enables sharks to target prey in a diversity of ocean environments . many species also have another peculiar trait - the ability to launch their jaws out of their mouths , open them extra wide , and grab prey by surprise . over the course of evolution , shark brains have expanded , coupled with the growth of their sensory organs . modern-day sharks can smell a few drops of blood and hear sounds underwater from 800 meters away . they 're particularly well-tuned to low frequencies , including those emitted by dying fish . and like cats , they have reflective membranes called tapeta lucida at the backs of their eyes that dramatically improve their vision in low light . as if these heightened abilities were n't enough , sharks have even honed a sixth sense . they 're able to hunt using a network of electrosensory cells called ampullae of lorenzini . these cells are filled with hypersensitive jelly which allows them to detect electrical signals from prey , including the slightest twitch of a muscle . some of the most iconic shark species , like great whites , makos , porbeagles , and salmon sharks owe their success to another surprising trait : warm blood inside a cold-blooded creature . inside their bodies , they have bundles of arteries and veins called rete mirabile . here , venous blood warmed up by the shark 's working muscles passes right next to arteries carrying cold , oxygen-rich blood from the gills . this arrangement transfers heat to the blood that gets cycled back to the body 's vital organs . warmer muscles enable faster , more powerful swimming , while warmer bellies aid digestion , and the more rapid development of young in utero . and warmer eyes and brains keep the sharks alert in cold waters . with these amazing adaptations , there 's more to revere than fear from the 500 shark species roaming our oceans . unfortunately , one-third of these species are threatened due to overfishing . after millions of years in the making , these apex predators may be meeting their greatest challenge yet .

sharks have been celebrated as powerful gods by some native cultures . for example , fijians believe the shark god dakuwaqa , could protect fisherman from the dangers at sea .

which statement is false ?

watch the center of this disk . you are getting sleepy . no , just kidding . i 'm not going to hypnotize you . but are you starting to see colors in the rings ? if so , your eyes are playing tricks on you . the disk was only ever black and white . you see , your eyes do n't always capture the world as a video camera would . in fact , there are quite a few differences , owing to the anatomy of your eye and the processing that takes place in your brain and its outgrowth , the retina . let 's start with some similarities . both have lenses to focus light and sensors to capture it , but even those things behave differently . the lens in a camera moves to stay focused on an object hurtling towards it , while the one in your eye responds by changing shape . most camera lenses are also achromatic , meaning they focus both red and blue light to the same point . your eye is different . when red light from an object is in focus , the blue light is out of focus . so why do n't things look partially out of focus all the time ? to answer that question , we first need to look at how your eye and the camera capture light : photoreceptors . the light-sensitive surface in a camera only has one kind of photoreceptor that is evenly distributed throughout the focusing surface . an array of red , green and blue filters on top of these photoreceptors causes them to respond selectively to long , medium and short wavelength light . your eye 's retinas , on the other hand , have several types of photoreceptors , usually three for normal light conditions , and only one type for lowlight , which is why we 're color blind in the dark . in normal light , unlike the camera , we have no need for a color filter because our photoreceptors already respond selectively to different wavelengths of light . also in contrast to a camera , your photoreceptors are unevenly distributed , with no receptors for dim light in the very center . this is why faint stars seem to disappear when you look directly at them . the center also has very few receptors that can detect blue light , which is why you do n't notice the blurred blue image from earlier . however , you still perceive blue there because your brain fills it in from context . also , the edges of our retinas have relatively few receptors for any wavelength light . so our visual acuity and ability to see color falls off rapidly from the center of our vision . there is also an area in our eyes called the blind spot where there are no photoreceptors of any kind . we do n't notice a lack of vision there because once again , our brain fills in the gaps . in a very real sense , we see with our brains , not our eyes . and because our brains , including the retinas , are so involved in the process , we are susceptible to visual illusions . here 's another illusion caused by the eye itself . does the center of this image look like it 's jittering around ? that 's because your eye actually jiggles most of the time . if it did n't , your vision would eventually shut down because the nerves on the retina stop responding to a stationary image of constant intensity . and unlike a camera , you briefly stop seeing whenever you make a larger movement with your eyes . that 's why you ca n't see your own eyes shift as you look from one to the other in a mirror . video cameras can capture details our eyes miss , magnify distant objects and accurately record what they see . but our eyes are remarkably efficient adaptations , the result of hundreds of millions of years of coevolution with our brains . and so what if we do n't always see the world exactly as it is . there 's a certain joy to be found watching stationary leaves waving on an illusive breeze , and maybe even an evolutionary advantage . but that 's a lesson for another day .

also in contrast to a camera , your photoreceptors are unevenly distributed , with no receptors for dim light in the very center . this is why faint stars seem to disappear when you look directly at them . the center also has very few receptors that can detect blue light , which is why you do n't notice the blurred blue image from earlier .

when we look directly at a dim star , it can disappear from view because _____ .

there 's a concept that 's crucial to chemistry and physics . it helps explain why physical processes go one way and not the other : why ice melts , why cream spreads in coffee , why air leaks out of a punctured tire . it 's entropy , and it 's notoriously difficult to wrap our heads around . entropy is often described as a measurement of disorder . that 's a convenient image , but it 's unfortunately misleading . for example , which is more disordered - a cup of crushed ice or a glass of room temperature water ? most people would say the ice , but that actually has lower entropy . so here 's another way of thinking about it through probability . this may be trickier to understand , but take the time to internalize it and you 'll have a much better understanding of entropy . consider two small solids which are comprised of six atomic bonds each . in this model , the energy in each solid is stored in the bonds . those can be thought of as simple containers , which can hold indivisible units of energy known as quanta . the more energy a solid has , the hotter it is . it turns out that there are numerous ways that the energy can be distributed in the two solids and still have the same total energy in each . each of these options is called a microstate . for six quanta of energy in solid a and two in solid b , there are 9,702 microstates . of course , there are other ways our eight quanta of energy can be arranged . for example , all of the energy could be in solid a and none in b , or half in a and half in b . if we assume that each microstate is equally likely , we can see that some of the energy configurations have a higher probability of occurring than others . that 's due to their greater number of microstates . entropy is a direct measure of each energy configuration 's probability . what we see is that the energy configuration in which the energy is most spread out between the solids has the highest entropy . so in a general sense , entropy can be thought of as a measurement of this energy spread . low entropy means the energy is concentrated . high entropy means it 's spread out . to see why entropy is useful for explaining spontaneous processes , like hot objects cooling down , we need to look at a dynamic system where the energy moves . in reality , energy does n't stay put . it continuously moves between neighboring bonds . as the energy moves , the energy configuration can change . because of the distribution of microstates , there 's a 21 % chance that the system will later be in the configuration in which the energy is maximally spread out , there 's a 13 % chance that it will return to its starting point , and an 8 % chance that a will actually gain energy . again , we see that because there are more ways to have dispersed energy and high entropy than concentrated energy , the energy tends to spread out . that 's why if you put a hot object next to a cold one , the cold one will warm up and the hot one will cool down . but even in that example , there is an 8 % chance that the hot object would get hotter . why does n't this ever happen in real life ? it 's all about the size of the system . our hypothetical solids only had six bonds each . let 's scale the solids up to 6,000 bonds and 8,000 units of energy , and again start the system with three-quarters of the energy in a and one-quarter in b . now we find that chance of a spontaneously acquiring more energy is this tiny number . familiar , everyday objects have many , many times more particles than this . the chance of a hot object in the real world getting hotter is so absurdly small , it just never happens . ice melts , cream mixes in , and tires deflate because these states have more dispersed energy than the originals . there 's no mysterious force nudging the system towards higher entropy . it 's just that higher entropy is always statistically more likely . that 's why entropy has been called time 's arrow . if energy has the opportunity to spread out , it will .

it continuously moves between neighboring bonds . as the energy moves , the energy configuration can change . because of the distribution of microstates , there 's a 21 % chance that the system will later be in the configuration in which the energy is maximally spread out , there 's a 13 % chance that it will return to its starting point , and an 8 % chance that a will actually gain energy .

systems move toward thermal equilibrium because , they move toward the energy configuration :

norman mclaren , the great 20th century pioneer of animation technique , once said , `` animation is not the art of drawings that move , but the art of movements that are drawn . what happens between each frame is more important than what exists on each frame . '' what did he mean ? well , for an object to appear in motion , it necessarily has to change in position over time . if time passes and no change in position occurs , the object will appear to be still . this relationship between the passage of time and the amount of change that occurs in that time is at the heart of every time-based art form , be it music , dance , or motion pictures . manipulating the speed and amount of change between the frames is the secret alchemy that gives animation the ability to convey the illusion of life . in animation , there are two fundamental principles we use to do this : timing and spacing . to illustrate the relationship between them , we 'll use a timeless example : the bouncing ball . one way to think about timing is that it 's the speed , or tempo , at which an action takes place . we determine the speed of an action by how many pictures , or frames , it takes to happen . the more frames something takes to happen , the more time it spends on screen , so the slower the action will be . the fewer frames something takes to happen , the less screen time it takes , which gives us faster action . the timing is about more than just speed , it 's also about rhythm . like a drumbeat or melody only exists when a song is being played , the timing of an action only exists while it 's happening . you can describe it in words , say , something will take 6 frames , 18 frames , or so on . but to really get a sense of it , you need to act it out or experience it as it would happen in , well , real time . now , the timing of an action all depends on the context of the scene and what you 're trying to communicate . what is doing the acting , and why ? let 's take our example . what makes a ball bounce ? the action we 're talking about here is a result of interacting physical forces , a moving ball 's tendency to stay in motion , or its force of momentum vs. the constant force of gravity bringing it back down earth . the degree to which these invisible forces apply , and the reason why the ball behaves the way it does , all depends on the physical properties of the ball . a golf ball is small , hard and light . a rubber ball is small , soft and lighter . a beach ball is large , soft and light . and a bowling ball is large , hard and heavy . so , each ball behaves very differently , according to its properties . let 's get a sense of the visual rhythm of each . each ball plays its own beat and tells us something about itself and the time it takes to travel across the screen . the visual rhythm of these hits is the timing . okay , let 's start animating our ball , bouncing up and down with a simple cycle of drawings . we 'll draw a circle here , call it point a , our starting point . we 'll have it hit the ground here , point b . let 's say it takes about a second to hit the ground and come back up again . this is our timing . our spacing is where we position the circle in the frames between point a and point b . if we were to move our ball in evenly-spaced increments , we 'd get something like this . it 's not really telling us anything about itself . is it a bouncing ball or a circle on an elevator ? let 's look at our footage again and think about what 's going on as each ball bounces . following each impact with the ground , the ball 's upward momentum is eventually overcome by gravity . this happens at the peak of each arc . as things change direction , the motion is slowest . we see here the successive positions of the ball are close together . the ball then speeds up as it falls , and is at its fastest when it 's approaching and hitting the ground . we can see here each position is further apart . the change in position between frames is the spacing . the smaller the change , the slower the action will appear . the greater the change , the faster it will appear . for an action to decelerate , each change in position must be less than the change before it . likewise , for an action to speed up , or accelerate , each successive change must be greater . let 's change the mechanical spacing of our animated bounce to reflect what we observed in the footage . slow at the top , fast when it 's hitting the ground . simply by adjusting the spacing , we 've succeeded in suggesting the forces of momentum and gravity at play and achieved a much more realistic motion . same timing but different spacing gives us vastly different results . and in reality , as a ball bounces , the physics of gravity eventually defeat the tendency of the ball to stay in motion . you can see this here in the decreasing height of each successive bounce . however , again , this decrease varies according to the properties of the ball . even though these circles are the same size here , they 're each telling us a different story about themselves , purely in how they move . the relationship between these principles of timing and spacing can be applied in countless ways and used to animate all types of action : a yo-yo , a punch , a gentle tap , a push , a saw , the sun traveling across the sky , a pendulum . animation is a time-based art form . it may incorporate the aesthetic elements of other graphic arts , like illustration or painting , but what sets animation apart is that , here , what you see is less important that what you do n't see . an object 's superficial appearance only tells us so much about itself . it 's only when it 's in motion that we really understand its nature .

one way to think about timing is that it 's the speed , or tempo , at which an action takes place . we determine the speed of an action by how many pictures , or frames , it takes to happen . the more frames something takes to happen , the more time it spends on screen , so the slower the action will be .

we determine the speed of an action by how many ________ it takes to happen .

it was a night like any other night , except here i was climbing the platonic peaks like romeo on a second date . ( ugh ) i was there for the dame . she had eyes like imaginary numbers and curves that went on forever . said she wanted to go home . said i could help . said the pay was good . did n't say anything about climbing a ... voice : `` who 's there ? '' manny brot : `` manny brot , private eye . '' voice : `` what are you doing here ? '' `` a pretty number sent me to find a stolen dingus . '' voice : `` well , to enter the cave , you must answer my riddles three . '' what was it with riddles , and why do they always come in threes ? `` is it an egg ? '' `` no . why would it be an egg ? '' `` it 's usually an egg . '' `` what can i hold in my hand , but has zero area ? '' `` is it a dodo egg ? '' `` it 's not an egg ! '' i took out the rock that had nearly brained me before and gave it a hard ponder . the size of the rising bump on my conk said to me that this thing had area , and a lot of it . but what if i carved out a triangle from this side here ? as any mook could see , this triangle had a quarter of the area of the full triangle . i did the same thing again with each of the smaller triangles . again , a quarter of the remaining area -- gone . and i just kept going . after an infinite number of cuts , i was satisfied that my triangle had zero area . a bounded shape with zero area . now , it 's not often that i surprise myself , but my own two mitts had created something crazy , and new . `` very good . ( ahem ) now , show me a shape with finite area , but an infinitely long perimeter . '' `` let me get this straight . if i want to make a snip in the border of this shape , smooth it out , and lay it on the ground ... `` `` it would go on for ... `` `` wait 'til i 'm through , and then you can talk . it would go on forever . '' `` are you through ? '' `` yeah . '' `` so show me that shape then . '' mmm ... i had n't been this stuck since the rubik 's cube fiasco of '58 . all the shapes i knew had perimeters . circles : 2πr . triangles : sum of their sides . what 's this ? an angle . an angle from heaven . what if i were to pinch each side , like so . a third of the way through , just so . and do it again , and again , and again . after each pinch , the perimeter got a third longer because where there had been three line segments , now there were four . as for the area , every pinch made more triangles , that 's true . but those triangles were getting smaller and smaller . you could say that the area was converging , approaching a fixed number , while the perimeter was just getting bigger and bigger , uncontrollably ballooning like an overindulgent birthday clown . after infinity pinches , flimflam , there it was : finite area , but infinite perimeter . now that is a piece of work . `` oh , you 're good . ( ahem ) riddle three : show me a picture that if i magnify it under my microscope , i 'll keep seeing the original picture , no matter how much i zoom in . '' `` you 're a strange little man . '' `` thank you . '' i was out of ideas , so i looked at my muse , my complex dora . voice : `` who 's the dame ? '' and then it hit me . `` she 's a heart breaker , my fractal femme fatale . will she do ? '' `` yes , she 'll do just fine . '' ( lightning ) it was dark , and at first i thought the cave was empty , but then i noticed : the box . the dame had played me like a triangle . she had told me she wanted to go home . ( lightning ) what she really wanted was to bring her home here . the fractals spread everywhere . most of them the same no matter how deep you looked at them , like dora 's mugshot . some had infinitely long perimeters , others were objects with no area or volume , all of them created through infinite repetition . so , you wanted to know what fractals are ? well , kid , they 're the stuff that dreams are made of . ( music )

it was a night like any other night , except here i was climbing the platonic peaks like romeo on a second date . ( ugh ) i was there for the dame .

which of these is most like a fractal ?

once upon a time , south america lived harmoniously alongside africa until a crack in the earth drove the two continents apart . this breakup began about 200 million years ago during the separation of the supercontinent known as pangaea . their proximity back then explains why the same plant fossils and reptile fossils , like the mesosaurus , can be found on the south american east coast and african west coast . however , this evidence does not account for how the continents moved apart . for that , we 'll need to take a close look at the earth below our feet . though you may not realize it , the ground below you is traveling across the earth at a rate of about 10 cm/year , or the speed at which your fingernails grow . this is due to plate tectonics , or the large-scale movement of earth 's continents . the motion occurs within the top two layers of the earth 's mantle , the lithosphere and asthenosphere . the lithosphere , which includes the crust and uppermost mantle , comprises the land around you . beneath the lithosphere is the asthenosphere the highly viscous but solid rock portion of the upper mantle . it 's between 80 and 200 km below the earth 's surface . while the asthenosphere wraps around the earth 's core as one connected region , the lithosphere is separated on top into tectonic plates . there are seven primary tectonic plates that compose the shape of the planet we know today . like the other smaller tectonic plates , the primary plates are about 100 km thick and are composed of one or two layers : continental crust and oceanic crust . continental crust forms the continents and areas of shallow water close to their shores , whereas oceanic crust forms the ocean basins . the transition from the granitic continental crust to the basaltic oceanic crust occurs beyond the continentel shelf , in which the shore suddenly slopes down towards the ocean floor . the south american plate is an example of a tectonic plate made of two crusts : the continent we know from today 's map and a large region of the atlantic ocean around it . collectively comprising the lithosphere , these plates are brittler and stiffer than the heated , malleable layer of the asthenosphere below . because of this , the tectonic plates float on top of this layer , independently of one another . the speed and direction in which these tectonic plates move depends on the temperature and pressure of the asthenosphere below . scientists are still trying to nail down the driving forces behind this movement , with some theories pointing towards mantle convection , while others are examining the influence of the earth 's rotation and gravitational pull . though the mechanics have not been sorted out , the scientific community agrees that our tectonic plates are moving and have been for billions of years . because these plates move independently , a fair amount of pushing and pulling between the plates occurs . the first type of interaction is a divergent boundary , in which two plates move away from one another . we see this in the mid-atlantic ridge between south america and africa . the next interaction is when two plates collide , known as a convergent boundary . in this instance , the land is pushed upward to form large mountain ranges , like the himalayas . in fact , the indian plate is still colliding with the eurasian plate , which is why mount everest grows one cm/year . finally , there 's the transform boundaries , where two plates scrape past one another . the grinding of the transform boundary leads to many earthquakes , which is what happens in the 810 mile-long san andreas fault . the moving earth is unstoppable , and , while a shift of 10 cm/year may not seem like a lot , over millions of years our planet will continue to dramatically change . mountains will rise , shorelines will recede , islands will pop up . in fact , one projected map shows the cities of los angeles and san francisco on top of each other . maybe south america and africa will come together again , too . only time will tell .

it 's between 80 and 200 km below the earth 's surface . while the asthenosphere wraps around the earth 's core as one connected region , the lithosphere is separated on top into tectonic plates . there are seven primary tectonic plates that compose the shape of the planet we know today . like the other smaller tectonic plates , the primary plates are about 100 km thick and are composed of one or two layers : continental crust and oceanic crust . continental crust forms the continents and areas of shallow water close to their shores , whereas oceanic crust forms the ocean basins .

how many tectonic plates are there ?

humans have done a pretty good job of exploring the earth thus far , climbing mountains and crossing continents and planting our flags all over the place in the name of science . but one part of the world that has remained pretty mysterious to us also happens to cover more than 70 % of its surface : the ocean . yes , we ’ ve sailed across it plenty of times . and drilled for oil in it . and managed to create reality shows about fishing in it . but , from glowing oceans to massive deep-sea creatures , and underwater ecosystems with thousands of undiscovered , basically-alien species -- we still have a lot to learn about it . probably more than any place on earth , the ocean is full of fascinating stuff that we just don ’ t know . not yet . [ music playing ] number one : what ’ s the ocean floor like ? fact is , we still don ’ t know exactly what the ocean floor looks like in most places . the national oceanic and atmospheric administration says that 95 % of the ocean 's bottom remains unseen by humans . as a result , we have a way better picture of the surfaces of other planets than we do of most of the seafloor . in 2014 , a team of scientists created a map of the seafloor using data from satellites equipped with special sensors called radar altimeters . these instruments could precisely measure the distance from the satellite to the surface of the ocean below . essentially , any large mountains or canyons on the ocean floor have a slight gravitational effect on the ocean surface , creating bumps and dips , respectively . these variations are of course too subtle to be detected by human eyes , but they can be measured by these ultra-precise satellite altimeters -- and , after adjusting for the effect of waves and tides , tell scientists what ’ s on the seafloor . this map spans the entire ocean floor , which is awesome , and we ’ re all glad that it exists , but it only has a resolution of about 5 kilometers , which is pretty low . by comparison , most of the surface of mars , venus , and the moon have been mapped to resolutions of 100 meters or less . so , if we want to know what ’ s going on down there and really explore the ocean , detecting life , specific mineral formations , or wrecks , we ’ re gon na need a better map . number two : what ’ s under the seafloor ? ok , probably thinking that you know what ’ s down there : rock . yes . but not just rock . in 2015 , scientists reported that they had drilled down about 2 and a half kilometers below the seafloor off the coast of japan , and discovered living microbes . there were only about 10 to 10,000 microorganisms in a cubic centimeter of sediment that they studied , compared to like billions that you ’ d find in the same amount of dirt from your garden . but still : there 's life down there , even in the intense heat and pressure many kilometers below where the ocean stops . and the genomes of these under-sea microbes showed that they were actually more similar to the kind you ’ d find in forest soil , rather than the ones in seafloor sediments . so it ’ s possible that these microbes are descendants of terrestrial ones from 20 million years ago , that just adapted when their habitat began to get buried way beneath the ocean . so , who knows what other kinds of life could exist in deep marine sediments , or what they could tell us about what life on earth used to be like ? number three : brine pools . we ’ ve all seen lakes and rivers on land , but what about lakes that are … underwater ? sounds a little bit unreal , like maybe it ’ s from a sponge bob episode but these features actually exist -- pockets of seawater that have a different composition than the surrounding ocean : because they ’ re super salty . they ’ re known as brine pools , and they seem to have formed when layers of salt from evaporated oceans millions of years ago got buried under layers of sediment . seawater can reach these deposits and mix with the salt , forming a dense brine that flows out of the seafloor , sometimes filled with oils or methane gas . some brine pools , like those found deep in the gulf of mexico , are four times as salty as the ocean water around it . and the brine is so dense that submersibles can even “ float ” on top of it , like a boat on a lake . all of this salt makes brine pools lethal to larger animals . but colonies of halophilic -- or salt-loving -- microorganisms can flourish there , usually in much higher concentrations than the nearby normal seawater . some pools are even lined with mussels that have symbiotic bacteria in their gills , which use the methane in the brine to make energy for the mussels . but there ’ s a ton that we don ’ t know about these weird underwater salt lakes -- like how brine pools can be so different from each other -- and why some have mussels and others don ’ t -- and even how many there are ! number four : milky seas . also known as mareel , this is a phenomenon in which thousands of square kilometers of the ocean ’ s surface glow a brilliant whitish-blue . it lasts for such a short time , and there have been so few recorded sightings , that these glowing seas were thought to be a myth made up by crazy sailors… … until 2005 -- when a group of researchers was studying satellite pictures of a swath of the indian ocean from 1995 . these pictures showed an area of about 15,000 kilometers-square , around the size of connecticut , glowing for 3 nights . it was the first scientific evidence of the phenomenon , but the glowing waters are still not very well understood . some have suggested that the glow is caused by a mass of tiny dinoflagellates called noctiluca scintillans known as “ sea sparkles ” for the way they glow when disturbed . these protists are what cause the picturesque glittering waves along coastlines in some parts of the world . but the 2005 study found that it was “ unlikely , if not impossible ” that the short-lived glowing of dinoflagellates was what scientists had been seeing from space . the prevailing theory these days is that milky seas are caused by massive colonies of bioluminescent bacteria that are growing on top of an algal bloom . but we ’ re still not sure how or why these ephemeral masses of bacteria gather , glow , and disappear . number five : the 52 hertz whale . you ’ d think we would know a lot about whales . i mean , they ’ re big , and we have their skeletons , and we can observe their migratory patterns . but one thing we still have a lot more to learn about is their songs -- from why some whales make them , to how an animal without vocal cords … or lips … manages to make song-like sounds . and then there ’ s this question -- what whale is producing the 52 hertz song , and why ? this whale song was first noted by a technician on december 7th , 1992 in the northeast pacific ocean . it sounded like a blue whale , but blue whale cries usually are somewhere between 15 and 20 hertz in pitch . so , blue whales in the pacific typically sound like this : [ blue whale cry playing ] but this whale song , played at the same speed , sounded like this : [ 52 hertz song playing ] this high-pitch noise seemed to be unique to one animal -- a whale that became known as 52 blue . this raises a lot of questions , and we have to know more about whales to be able to answer some of them , like , why does this one whale sound different ? and can others even hear it ? and if they can hear it , do they understand ? some people latched onto to the idea that 52 blue is a lonely whale crying out to others that might not hear it or wouldn ’ t call back . but several scientists have rejected this lonely narrative , and think that other whales may be able to understand its call , even if they can ’ t make that call themselves . also , 52 blue seems to migrate independently from any other whales . but its migratory patterns do look kind of like those of blue whales -- scientists have been tracking it up and down the north pacific from alaska to mexico for years now . so some researchers think it might have some malformation that has changed how it sings , or maybe it ’ s even a hybrid between a blue whale and another species . whether or not it ’ s a lonely whale , 52 blue is an oddity that people seem to love . number six : upsweep . now , ocean sounds are practically their own field of study , noaa has been monitoring acoustics in the ocean for decades now . instead of microphones , which are used to collect sound in air , noaa uses hydrophones to record underwater sounds . mostly , these hydrophones are used to listen to the ambient sound of the ocean , to see how humans might interfere with it , and to listen for things like earthquakes and whale calls . and sometimes , they record things that are hard to explain , at least for a while . in 1997 , for example , there was what was known as the bloop , an extremely loud , low-frequency sound heard by hydrophones some 5,000 kilometers apart . oceanographers recently determined that it was the result of an icequake -- the cracking and collapse of glaciers into the ocean , in this case on the coast of antarctica . but there ’ s another mystery sound from the ocean , known as upsweep . recorded in august 1991 , it sounds like a repeating “ boop ” that picks up at the end -- sweeping up -- kind of like the “ red alert ” sound effect you hear on spaceships in sci-fi movies . but instead of trying to describe it , i could just play it for you . [ boop playing ] since 1991 , this sound has been heard regularly in the pacific ocean , and it seems to be seasonal , usually becoming more common in spring and fall . researchers have tracked the sound to a part of the pacific that has lots of volcanic and seismic activity , which seem to be important clues . but according to noaa , “ the origin of the sound is unresolved. ” number seven : why are deep-sea creatures so huge ? from the kraken to sea dragons , all of our favorite mythical sea monsters are gigantic . and the fact is , in real life , many deep-sea creatures are unusually huge . this phenomenon is called deep-sea gigantism . but what drives it is … you guessed it ! … unknown ! in the deep sea , and especially near the polar oceans , some animals seem to get really huge -- like colossal squids , giant isopods , and japanese spider crabs . scientists aren ’ t sure why , but they do have some guesses . there ’ s bergmann ’ s rule , for example , which suggests that temperature may influence gigantism . this might be because larger animals have less surface area relative to volume , so they radiate less heat based on their mass and stay warmer in colder climates . and then there ’ s klieber ’ s law , which states that more massive animals generally have lower metabolic rates -- and therefore need less high-quality food -- - to survive . still other theories suggest that gigantism may help organisms resist increased pressure of the deep sea . but we don ’ t really have conclusive biological reasons why these giant creatures exist . so , the ocean is just full o ’ mysteries , maybe because it ’ s so huge and dark and deep . but just so you know that we ’ re not hyping you -- we ’ re not saying that these 7 topics are things that science can ’ t explain . instead , you should just think of them as reminders of how much we still have to learn about the ocean . as our technology improves , and our access to the ocean takes us to new depths , we ’ ll be able to see and hear and sample more stuff than we ever have before . so in time , these puzzles will be solved , and new creatures will be discovered , and our understanding of our planet , and the life on it , will be that much … deeper . thank you for watching this scishow list show , and thanks especially to all of our patrons on patreon who make this show possible . if you want to help us keep making shows like this , you can go to patreon.com/scishow­ . and don ’ t forget to go to youtube.com/scishow and subscribe !

this whale song was first noted by a technician on december 7th , 1992 in the northeast pacific ocean . it sounded like a blue whale , but blue whale cries usually are somewhere between 15 and 20 hertz in pitch . so , blue whales in the pacific typically sound like this : [ blue whale cry playing ] but this whale song , played at the same speed , sounded like this : [ 52 hertz song playing ] this high-pitch noise seemed to be unique to one animal -- a whale that became known as 52 blue .

blue whale calls are normally somewhere between ________ hertz in pitch .

take a look out your window , put on your glasses if you wear them . you might want to grab a pair of binoculars , too , or a magnifying lens . now , what do you see ? well , whatever it is , it 's not the multiple layers of glass right in front of you . but have you ever wondered how something so solid can be so invisible ? to understand that , we have to understand what glass actually is , and where it comes from . it all begins in the earth 's crust , where the two most common elements are silicon and oxygen . these react together to form silicon dioxide , whose molecules arrange themselves into a regular crystalline form known as quartz . quartz is commonly found in sand , where it often makes up most of the grains and is the main ingredient in most type of glass . of course , you probably noticed that glass is n't made of multiple tiny bits of quartz , and for good reason . for one thing , the edges of the rigidly formed grains and smaller defects within the crystal structure reflect and disperse light that hits them . but when the quartz is heated high enough the extra energy makes the molecules vibrate until they break the bonds holding them together and become a flowing liquid , the same way that ice melts into water . unlike water , though , liquid silicon dioxide does not reform into a crystal solid when it cools . instead , as the molecules lose energy , they are less and less able to move into an ordered position , and the result is what is called an amorphous solid . a solid material with the chaotic structure of a liquid , which allows the molecules to freely fill in any gaps . this makes the surface of glass uniform on a microscopic level , allowing light to strike it without being scattered in different directions . but this still does n't explain why light is able to pass through glass rather than being absorbed as with most solids . for that , we need to go all the way down to the subatomic level . you may know that an atom consists of a nucleus with electrons orbiting around it , but you may be surprised to know that it 's mostly empty space . in fact , if an atom were the size of a sports stadium , the nucleus would be like a single pea in the center , while the electrons would be like grains of sand in the outer seats . that should leave plenty of space for light to pass through without hitting any of these particles . so the real question is not why is glass transparent , but why are n't all materials transparent ? the answer has to do with the different energy levels that electrons in an atom can have . think of these as different rows of seats in the stadium stands . an electron is initially assigned to sit in a certain row , but it could jump to a better row , if it only had the energy . as luck would have it , absorbing one of those light photons passing through the atom can provide just the energy the electron needs . but there 's a catch . the energy from the photon has to be the right amount to get an electron to the next row . otherwise , it will just let the photon pass by , and it just so happens that in glass , the rows are so far apart that a photon of visible light ca n't provide enough energy for an electron to jump between them . photons from ultraviolet light , on the other hand , give just the right amount of energy , and are absorbed , which is why you ca n't get a suntan through glass . this amazing property of being both solid and transparent has given glass many uses throughout the centuries . from windows that let in light while keeping out the elements , to lenses that allow us to see both the vast worlds beyond our planet , and the tiny ones right around us . it is hard to imagine modern civilization without glass . and yet for such an important material we rarely think about glass and its impact . it is precisely because the most important and useful quality of glass is being featureless and invisible that we often forget that it 's even there .

but when the quartz is heated high enough the extra energy makes the molecules vibrate until they break the bonds holding them together and become a flowing liquid , the same way that ice melts into water . unlike water , though , liquid silicon dioxide does not reform into a crystal solid when it cools . instead , as the molecules lose energy , they are less and less able to move into an ordered position , and the result is what is called an amorphous solid .

when liquid silicon dioxide forms , it results in an ________ .

mastering any physical skill , be it performing a pirouette , playing an instrument , or throwing a baseball , takes practice . practice is the repetition of an action with the goal of improvement , and it helps us perform with more ease , speed , and confidence . so what does practice do in our brains to make us better at things ? our brains have two kinds of neural tissue : grey matter and white matter . the grey matter processes information in the brain , directing signals and sensory stimuli to nerve cells , while white matter is mostly made up of fatty tissue and nerve fibers . in order for our bodies to move , information needs to travel from the brain 's grey matter , down the spinal cord , through a chain of nerve fibers called axons to our muscles . so how does practice or repetition affect the inner workings of our brains ? the axons that exist in the white matter are wrapped with a fatty substance called myelin . and it 's this myelin covering , or sheath , that seems to change with practice . myelin is similar to insulation on electrical cables . it prevents energy loss from electrical signals that the brain uses , moving them more efficiently along neural pathways . some recent studies in mice suggest that the repetition of a physical motion increases the layers of myelin sheath that insulates the axons . and the more layers , the greater the insulation around the axon chains , forming a sort of superhighway for information connecting your brain to your muscles . so while many athletes and performers attribute their successes to muscle memory , muscles themselves do n't really have memory . rather , it may be the myelination of neural pathways that gives these athletes and performers their edge with faster and more efficient neural pathways . there are many theories that attempt to quantify the number of hours , days , and even years of practice that it takes to master a skill . while we do n't yet have a magic number , we do know that mastery is n't simply about the amount of hours of practice . it 's also the quality and effectiveness of that practice . effective practice is consistent , intensely focused , and targets content or weaknesses that lie at the edge of one 's current abilities . so if effective practice is the key , how can we get the most out of our practice time ? try these tips . focus on the task at hand . minimize potential distractions by turning off the computer or tv and putting your cell phone on airplane mode . in one study , researchers observed 260 students studying . on average , those students were able to stay on task for only six minutes at a time . laptops , smartphones , and particularly facebook were the root of most distractions . start out slowly or in slow-motion . coordination is built with repetitions , whether correct or incorrect . if you gradually increase the speed of the quality repetitons , you have a better chance of doing them correctly . next , frequent repetitions with allotted breaks are common practice habits of elite performers . studies have shown that many top athletes , musicians , and dancers spend 50-60 hours per week on activities related to their craft . many divide their time used for effective practice into multiple daily practice sessions of limited duration . and finally , practice in your brain in vivid detail . it 's a bit surprising , but a number of studies suggest that once a physical motion has been established , it can be reinforced just by imagining it . in one study , 144 basketball players were divided into two groups . group a physically practiced one-handed free throws while group b only mentally practiced them . when they were tested at the end of the two week experiment , the intermediate and experienced players in both groups had improved by nearly the same amount . as scientists get closer to unraveling the secrets of our brains , our understanding of effective practice will only improve . in the meantime , effective practice is the best way we have of pushing our individual limits , achieving new heights , and maximizing our potential .

so how does practice or repetition affect the inner workings of our brains ? the axons that exist in the white matter are wrapped with a fatty substance called myelin . and it 's this myelin covering , or sheath , that seems to change with practice . myelin is similar to insulation on electrical cables . it prevents energy loss from electrical signals that the brain uses , moving them more efficiently along neural pathways .

what is myelin ?

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 .

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 .

what is the cajon 's striking surface more commonly known as ?

translator : andrea mcdonough reviewer : bedirhan cinar 9th of january , 2007 joshua bell , one of the greatest violinist in the world , played to a packed audience at boston 's stately symphony hall of 1,000 people where most seats went for more than $ 100 . he was used to full , sell-out shows . he was at the peak of his abilities and fame . three days later , joshua bell played to an audience of nobody ! well , maybe six people paused for a moment , and one child stopped for a while looking , as if he understood that something special was happening . joshua said of the experience , `` it was a strange feeling that people were actually ignoring me . '' joshua bell was playing violin in a subway station . `` at a music hall , i 'll get upset if someone coughs or if someone 's cell phone goes off , but here my expectations quickly diminished . i was oddly grateful when somebody threw in a dollar . '' what changed ? same music , on the same violin , played with the same passion and by the same man . why did people listen and then not listen ? aristotle would be able to explain . what does it take to persuade people ? 2,300 years ago , aristotle wrote the single most important work on persuasion , < i > rhetoric < /i > , the 3 means of persuasion : logos , ethos , and pathos . logos is that the idea makes sense from the audience 's point of view . this is usually different from the speaker 's point of view , so work needs to be done to make the idea relevant to the world view , the pains and the challenges of the listeners . a good argument is like good music . good music follows some rules of composition ; good arguments follow some rules of logic . it makes sense to the audience . ethos is reputation , what are you known for ; credibility , do you look and act professional ; trustworthy , are your motives clear , do you show the listener that you care about them as much as yourself ? authority is confidence plus a concise message , a clear , strong voice . pathos is the emotional connection . stories are an effective human tool for creating an emotional connection . there are moments where an audience is not ready to hear the message . a speaker must create the right emotional environment for their message . what changed ? why did people travel for miles to hear him play one night , and not even pause for moment to listen the next morning ? the answer is that ethos and pathos were missing . ethos the fact that the great concert hall hosts joshua 's concert transfers its trust to joshua . we trust the institution , we now trust joshua . the subway does not have our trust for musical talent , we do not expect to find great art , great music , or great ideas , so it confers no trust to joshua . pathos the concert hall is designed for an emotional bond between an audience and an artist , a subway platform is not . the hustle and movement and stress is just not conducive to the emotional connection needed between performer and listener . logos , ethos , pathos , the idea is nothing without the rest . this is what joshua bell learned on that cold , january day in 2007 . if you have a great idea , how do you build credibility and emotional connection ?

joshua said of the experience , `` it was a strange feeling that people were actually ignoring me . '' joshua bell was playing violin in a subway station . `` at a music hall , i 'll get upset if someone coughs or if someone 's cell phone goes off , but here my expectations quickly diminished .

according to neill , why did people refuse to listen to joshua bell when he was n't playing in the symphony hall ?

so you see a few cubes sitting in an art gallery , and you think to yourself , `` this is the greatest hoax that anyone has ever pulled off . '' you immediately walk away , discouraged by the wide gulf between what you hope for when you walk into a museum and what they 've presented to you . how did we get here ? how could these cubes that the artist did n't even make with their own hands be important ? this is the case for minimalism . first off , we 're not talking about minimalism as a general sensibility or the life-changing magic of tidying up . we 're talking about the art of a particular moment in time . namely , the 1960s , when all of a sudden , there was a lot of geometric , abstract art . some of it was painting by artists like frank stella and ellsworth kelly , but most of it was sculpture by artists like donald judd , carl andre , dan flavin , anne truitt , robert morris , tony smith , ronald bladen , and sol lewitt . art critics called it abc art , object art , primary structures , and cool art , but the term minimalism prevailed . these artists never called their art minimalist , by the way , nor did they like the term , or the implication that the work was so reductive that it was minimally art . but minimalism was a rejection of what came before . specifically , abstract expressionism , which dominated the art market in the 1950s . these new artists wanted to remove expression completely , remove emotion , empty the work of idiosyncratic gesture , make it resistant to biographical reading . their hard-edged , basic shapes and forms avoided allusion , metaphor , and overt symbolism . the forms were often repeated , one thing after another in regular , non-hierarchical arrangements , rejecting compositional balancing . no artist hemming and hawing over the canvas here . the objects were impersonal , many of them machine-made , fabricated from new and industrial materials . sometimes this entailed ready-made units , like andre 's bricks , or flavin 's fluorescent tubes . they did n't want you to ooh and ah , or admire the handling of paint . as lewitt once said , `` it is best that the basic unit `` be deliberately uninteresting . '' robert morris wrote that he could hear a resounding no at the time . `` no to transcendence and spiritual values , `` heroic scale , anguished decisions , `` historicizing narrative , valuable artifact , `` intelligent structure , interesting visual experience . '' but what they were saying yes to was a new and startling realness . abandoning the pedestal to dismantle the separation between you and the art . judd claimed these works are neither painting nor sculpture , but instead specific objects occupying real space . these objects are n't pointing to anything or referencing anything . andre called his work a kind of plastic poetry , in which elements are combined to produce space . so there is no illusion of space , it just is space . minimalism had its haters from the start . in 1967 , art critic michael fried attacked the work for being theatrical . for him it was an object in a room that had presence before a viewer , but it did not have what good art has , which is presentness , or , `` an instant of aesthetic experience `` which occurs in no real space or time at all . '' but fried really just ended up affirming exactly what the artists were trying to do : proving how radical it really was . despite its detractors , minimalism became all the rage . this geometric , unadorned style flowed throughout the worlds of fashion , theater , and design . in short , it was cool . and then because these artists were never trying to be minimalist to begin with , they moved on to other things and other kinds of art had its day . but minimalism changed things . for centuries , art had been trying to trick you , convince you that the hunk of rock was something other than a hunk of rock . but not this . you feel like there 's got ta be some secret to it , but there is n't . there 's nothing to interpret . this is what it is . it was n't supposed to look like art of the past , and it was n't supposed to function like it either . with minimalism , meaning does n't rest inside the object , waiting to be unlocked . the meaning is in the context , and exists in your interaction with it . but minimalism is a resistant lover . it 's just not that into you . it encourages observation , but does n't draw you in , and it was never trying to . remember , these objects were supposed to be emptied of prevention , of mastery , of the usual seduction between art and viewer , and of the grand , glorious traditions that preceded them . but the fetishization and commodification of minimalist art has complicated and polluted these ideas . what 's less real than million-dollar plywood boxes ? and yet , for me at least , minimalist art can still impart a strong feeling , a feeling for space , light , for presence and absence . you 're aware of your own body in the gallery as you 've never been before . you notice that your position in the room shapes your perception of the thing . you appreciate the architecture and the spareness , and in a world filled with complexity and information and lots and lots of stuff , this is a balm . this is a world more simplified than the actual world is , and that i can appreciate .

some of it was painting by artists like frank stella and ellsworth kelly , but most of it was sculpture by artists like donald judd , carl andre , dan flavin , anne truitt , robert morris , tony smith , ronald bladen , and sol lewitt . art critics called it abc art , object art , primary structures , and cool art , but the term minimalism prevailed . these artists never called their art minimalist , by the way , nor did they like the term , or the implication that the work was so reductive that it was minimally art .

what are other cultural sectors that have been influenced by the abstract minimalist art movement ? please give examples .

can you imagine a party where every movement , from the slightest gesture to walking across the room , and every visual detail , from furniture to hemline length , were governed by a complex system of rules and procedures ? for centuries , such rituals were commonplace for european nobility . and while they 've gone out of fashion , we recognize the components under a familiar label : ballet . ballet , from italian `` balletto , '' or little dance , originated in renaissance italy as a combination of social dance and choreographed display at aristocratic gatherings . in many aspects , it was a way of controlling people in court with acceptable forms of behavior , such as the manner in which people stepped , bowed , or took someone 's hand . it also involved rules governing everything from attire to where one could walk or sit in relation to the king . over time , the study of ballet became a central element of court life , and proper grasp of the etiquette could make or break one 's success as a courtier . many of these court gestures can still be seen in modern ballet techniques . ballet was brought to france in the 16th century by catherine de ' medici , the italian wife of king henry ii . as celebrations became more lavish , so did the dance , with dancing masters teaching elaborate steps to young nobles and story elements providing a unifying theme . the focus shifted from participation to performance , and the form acquired more theatrical trappings , such as professionally designed sets and a slightly raised platform or stage with curtains and wings . but it was in the 17th century court of louis xiv that ballet was refined into the art we know today . louis himself had been trained in ballet from childhood . his early role as the sun god apollo at age fifteen cemented the central role ballet would play during his reign . it also earned him the title of sun king , with his splendid golden costume and choreography that promoted the idea of the king as a divinely ordained ruler . louis would go on to perform 80 roles in 40 major ballets , either as a majestic lead , or sometimes playing minor or comedic parts before emerging in the lead role as the end . he trained daily in ballet , as well as fencing and riding , and through his example , dancing became an essential skill for all gentlemen of the era . but louis xiv 's main contribution to ballet was not as a performer . his founding of the royal academy of dance in 1661 shifted control of ballet from local guilds to the royal court . as director , he appointed his personal ballet master and frequent performance partner pierre beauchamp , who codified the five main positions of the body still used today . through is collaborations with jean-baptiste lully , the director of the royal music academy , and famed playwright molière , beauchamp helped establish ballet as a grand spectacle . and in 1669 , a separate ballet academy was founded . the paris opera ballet survives today as the oldest ballet company in the world . ballet moved away from the royal court to the theater and survived the democratic revolutions and reforms that followed over the next century . with the advent of the romantic movement , fantasy and folklore themes became common motifs . and though the influence of ballet in france would decline , other countries , such as russia , would play a major role in its further development . fortunately , today most of us do n't have to learn a complicated set of steps just to socialize at a wedding . instead , we can go to the theater to see professionals who spend their lives training rigorously to perform feats that would have been unimagineable in louis xiv 's day .

the focus shifted from participation to performance , and the form acquired more theatrical trappings , such as professionally designed sets and a slightly raised platform or stage with curtains and wings . but it was in the 17th century court of louis xiv that ballet was refined into the art we know today . louis himself had been trained in ballet from childhood .

louis xiv greatly influenced ballet as we know it today . what elements did he introduce that we would still recognize ?

hi , i 'm medium invader from the classic video game space invaders , and i want to tell you a little bit about where video games came from . a video game is an electronic game that has an interface designed for human interaction on a video device . simple . video games are used by scientists , the military , and people like you , and their evolution has spread across arcades , consoles , computers , smart phones , and all kinds of other electronics . these days video games are everywhere , but they were actually made in science labs . in fact , the earliest u.s. video game patent on record was in 1948 , and at the time it was referred to as a cathode-ray tube amusement device . that 's a mouthful ! some of the earliest video games include the nimrod computer , oxo , tennis for two , and my personal favorite , spacewar ! but none of these early video games were ever sold to the public because they were either too huge or too expensive to get out of the lab . this all changed when a man named ralph baer looked at his television screen and wondered how else it might be used . in 1972 , baer 's idea to get video games out of the science lab and into the living room led to the release of a game console called odyssey . odyssey allowed you to play a game on your tv . at about the same time , two other people , nolan bushnell and ted dabney , were working on something similar in a little company called atari . you might have heard of it , and even if you have n't , i 'm sure that your dad has . atari 's first major game release was in 1972 , an arcade game called pong . it was an immediate hit , and it 's credited as the first commercially successful video game . atari then released a home version of pong in 1974 . by 1978 , competition between atari and another game company called midway was heating up . midway had licensed an arcade game for the japanese company , taito , that put them on the map . the game : space invaders . it featured iconic actors , like me , and it went on to become the second highest selling arcade game of all time . space invaders also helped kick off what is known as the golden age of arcade games . in response , atari followed with the release of the arcade game asteroids , which ranked sixth on the list of highest selling arcade games . it was a good game , but it 's no space invaders . by 1980 , color came to arcade games , and this was also the year that another video gaming milestone was born . pac-man , created by the japanese company namco , was brought to the u.s. by midway . important to the spread of video games into popular culture , pac-man was a character that could be licensed . it was n't long before it had a song on the charts , a saturday morning television show , and all sorts of other products . in just a year , pac-man arcade games made over one billion dollars in quarters . then , in 1981 , a company called nintendo started making waves in the u.s. video game market with their release of donkey kong . it was the earliest video game to have a story line . the story went a bit like this : donkey kong is the pet of a carpenter named jumpman . jumpman mistreats his pet ape , so the ape steals his girlfriend , leaving the game player to assume the role of jumpman and rescue the girl . jumpman was eventually renamed to mario . other iconic arcade games from the early 80s include frogger , dragon 's lair , and mario brothers . perhaps the last iconic game considered to be part of the golden age of arcade games is double dragon . it was the first really successful example of the beat-them-up genre . it was released in 1987 , and , like donkey kong , it featured a damsel in distress storyline , a storyline common in many video games . by the mid-90s , the golden age of arcade games was coming to an end , and the home game console was gaining in popularity . while arcade games continued to decline in sales over the years , the popularity of video games was merely beginning , and we 'll talk about that and a lot more in part two of a brief history of video games .

by the mid-90s , the golden age of arcade games was coming to an end , and the home game console was gaining in popularity . while arcade games continued to decline in sales over the years , the popularity of video games was merely beginning , and we 'll talk about that and a lot more in part two of a brief history of video games .

it took a while for video games to catch on . what factors do you think contribute to whether or not a new technology catches on ?

during the warmer months , especially at night during the full moon , horseshoe crabs emerge from the sea to spawn . waiting for them are teams of lab workers who capture the horseshoe crabs by the hundreds of thousands , take them to labs , harvest their cerulean blood , then return them to the sea . oddly enough , we capture horseshoe crabs on the beach because that 's the only place we know we can find them . a female horseshoe crab lays as many as 20 batches of up to 4,000 eggs on her annual visit to the beach . when the eggs hatch , the juvenile horseshoe crabs often stay near shore , periodically shedding their shells as they grow . once they leave these shallow waters , they do n't return until they reach sexual maturity ten years later . despite our best efforts , we do n't know where they spend those years . though we 've spotted the occasional horseshoe crab as deep as 200 meters below the ocean 's surface , we only see large groups of adults when they come ashore to spawn . horseshoe crab blood contains cells called amebocytes that protect them from infection by viruses , fungi , and bacteria . amebocytes form gels around these invaders to prevent them from spreading infections . this is n't unusual . all animals have protective immune systems . but horseshoe crab amebocytes are exceptionally sensitive to bacterial endotoxins . endotoxins are molecules from the cell walls of certain bacteria , including e. coli . large amounts of them are released when bacterial cells die , and they can make us sick if they enter the blood stream . many of the medicines and medical devices we rely on can become contaminated , so we have to test them before they touch our blood . we do have tests called gram stains that detect bacteria , but they ca n't recognize endotoxins which can be there even when bacteria are n't present . so scientists use an extract called lal produced from harvested horseshoe crab blood to test for endotoxins . they add lal to a medicine sample , and if gels form , bacterial endotoxins are present . today , the lal test is used so widely that millions of people who 've never seen a horseshoe crab have been protected by their blood . if you 've ever had an injection , that probably includes you . how did horseshoe crabs end up with such special blood ? like other invertebrates , the horseshoe crab has an open circulatory system . this means their blood is n't contained in blood vessels , like ours . instead , horseshoe crab blood flows freely through the body cavity and comes in direct contact with tissues . if bacteria enters their blood , it can quickly spread over a large area . pair this vulnerability with the horseshoe crab 's bacteria-filled ocean and shoreline habitats , and it 's easy to see why they need such a sensitive immune response . horseshoe crabs survived mass extinction events that wiped out over 90 % of life on earth and killed off the dinosaurs , but they 're not invincible . and the biggest disruptions they 've faced in millions of years come from us . studies have shown that up to 15 % of horseshoe crabs die in the process of having their blood harvested . and recent research suggests this number may be even higher . researchers have also observed fewer females returning to spawn at some of the most harvested areas . our impact on horseshoe crabs extends beyond the biomedical industry , too . coastal development destroys spawning sites , and horseshoe crabs are also killed for fishing bait . there 's ample evidence that their populations are shrinking . some researchers have started working to synthesize horseshoe crab blood in the lab . for now , we 're unlikely to stop our beach trips , but hopefully , a synthetic alternative will someday eliminate our reliance on the blood of these ancient creatures .

if you 've ever had an injection , that probably includes you . how did horseshoe crabs end up with such special blood ? like other invertebrates , the horseshoe crab has an open circulatory system .

where do adult horseshoe crabs live ?

you might think you know a lot about native americans through popular movies , books , and classes in school , but it turns out that a lot of what we think we know about famous native american figures is n't quite right . take sacajawea for example . you probably remember her as a beautiful indian woman who lived an exotic life serving as the all-knowing guide for lewis and clark 's famous expedition , right ? well , that 's not exactly how it happened . not much is known about sacajawea 's early childhood , but we do know that she was born in 1788 into the agaidika tribe of the lemhi shoshone in what is now idaho . in 1800 , when she was about 12 years old , sacajawea and several other girls were kidnapped by a group of hidatsa indians . she was taken as a captive to a hidatsa village in present-day north dakota . then , she was sold to a french canadian fur trapper named toussaint charbonneau . within a year or so , she was pregnant with her first child . soon after she became pregnant , the corps of discovery arrived near the hidatsa villages . captains meriwether lewis and william clark built fort mandan there , and then started interviewing people to help guide them on their perilous expedition . they agreed to hire sacajawea 's husband , charbonneau , with the understanding that his lovely wife would also come along as an interpreter . they figured her very presence would help any encounters with native tribes along the way . as clark noted in his journal , `` a woman with a party of men is a token of peace . '' shortly thereafter , sacajawea gave birth to a little boy named jean baptiste charbonneau . clark called him pompy . she carried pompy on a board strapped to her back as the corps of discovery forged on . besides interpreting the language when lewis and clark encountered indians , sacajawea 's activities as a member of the corps included digging for roots , collecting edible plants , and picking berries . in 1805 , the boat they were riding in was capsized . she dove into the water , recovering all the important papers and supplies that would otherwise have been lost , including the journals and records of lewis and clark . later that year , captain lewis and three men scouted 75 miles ahead of the expedition 's main party , crossing the continental divide . the next day they encountered a group of shishones . not only did they prove to be sacajawea 's band , but their leader , chief cameahwait , turned out to be her very own brother . after five years of separation since her kidnapping as a young girl , sacajawea and cameahwait had an emotional reunion . unfortunately , she quickly had to bid farewell to her beloved brother and continue on with the journey . at one point , the expedition became so difficult and freezing , the group was reduced to eating candles to survive . when temperatures finally became more bearable , sacajawea found , dug , and cooked roots to help the group regain their strength . on the return trip , they encountered an indian wearing a beautiful fur robe . lewis and clark wanted to bring the robe to thomas jefferson as a gift but had nothing to trade for it . so , sacajawea agreed to trade her most precious possession , her beaded belt , for the fur . a little over two years after the expedition began , it was finally over , ending in st. louis . today , we learn about sacajawea in school as a heroic guide , but her life , like most everyone 's , was much more complicated than history books sometimes give her credit for .

soon after she became pregnant , the corps of discovery arrived near the hidatsa villages . captains meriwether lewis and william clark built fort mandan there , and then started interviewing people to help guide them on their perilous expedition . they agreed to hire sacajawea 's husband , charbonneau , with the understanding that his lovely wife would also come along as an interpreter .

the president during the lewis and clark expedition was :

what do charles darwin , michael jordan , and yoda have in common ? they , like many other historical and fictive individuals , are bald , in some cases by their own choice . for centuries , a shining dome has been a symbol of intelligence , but despite this , many balding people still wish their hair would return . scientists have long pondered , `` why do some people lose their hair , and how can we bring it back ? '' the full-headed among us have about 100,000 to 150,000 hairs on our scalps , and scientists have discovered two things about this dense thicket . firstly , the sprouting hair we see is mostly made up of keratin , the protein leftover from dead cells that are forced upwards as new cells grow beneath them . secondly , the structures that drive hair growth are called hair follicles , a network of complex organs that forms before we 're born , and grows hair in an everlasting cycle . this cycle has three main phases . the first is anagen , the growth phase , which up to 90 % of your hair follicles are experiencing right now , causing them to push up hair at a rate of one centimeter per month . anagen can last for two to seven years , depending on your genes . after this productive period , signals within the skin instruct some follicles to enter a new phase known as catagen , or the regressing stage , causing hair follicles to shrink to a fraction of their original length . catagen lasts for about two to three weeks and cuts blood supply to the follicle , creating a club hair , meaning it 's ready to be shed . finally , hairs enter telogen , the resting phase , which lasts for ten to twelve weeks , and affects about 5-15 % of your scalp follicles . during telogen , up to 200 club hairs can be shed in a day , which is quite normal . then , the growth cycle begins anew . but not all heads are hairy , and , in fact , some of them grow increasingly patchy over time in response to bodily changes . 95 % of baldness in men can be attributed to male pattern baldness . baldness is inherited , and in people with this condition , follicles become incredibly sensitive to the effects of dihydrotestosterone , a hormonal product made from testosterone . dht causes shrinkage in these overly sensitive follicles , making hair shorter and wispier . but loss is n't sudden . it happens gradually , along a metric known as the norwood scale , which describes the severity of hair loss . first , hair recedes along the temples , then hair on the crown begins to thin in a circular pattern . at the highest rating on the scale , these balding areas meet and expand dramatically , eventually leaving only a ring of sparse hair around the temples and the back of the head . genetics is n't all that drives hair loss . long periods of stress can release signals that shock follicles and force them into the resting phase prematurely . some women experience this after childbirth . follicles might also lose the ability to go into anagen , the growth phase . people going through chemotherapy treatment temporarily experience this . but while balding may look permanent , scientific investigation has revealed the opposite . below the skin 's surface , the roots that give rise to our hair actually remain alive . using this knowledge , scientists have developed drugs that shorten the resting phase , and force follicles into anagen . other drugs combat male pattern baldness by blocking the conversion of testosterone to dht so that it does n't affect those sensitive follicles . stem cells also play a role in regulating the growth cycle , and so scientists are investigating whether they can manipulate the activity of these cells to encourage follicles to start producing hair again . and in the meantime , while scientists hone their hair-reviving methods , anyone going bald , or considering baldness , can remember that they 're in great company .

at the highest rating on the scale , these balding areas meet and expand dramatically , eventually leaving only a ring of sparse hair around the temples and the back of the head . genetics is n't all that drives hair loss . long periods of stress can release signals that shock follicles and force them into the resting phase prematurely .

imbalance of hormones is linked with hair loss . researchers are investigating hormone replacement therapy ( hrt ) by using estrogen and progesterone to reverse this . what could be the risks in adopting such approach ?

translator : andrea mcdonough reviewer : jessica ruby so two guys walk into a bar . really ? no , seriously . two guys walk into a bar , an ice cream bar : dave , a physicist working on the large hadron collider at cern , the european laboratory for particle physics , and steve , a blues singer . `` dave , how 's it going ? '' `` steve , good to see you ! '' `` two scoops of chocolate almond for me . '' `` vanilla shake . '' `` hey , i just saw something about the lhc on tv . you guys found bozo in your detector ? '' `` well , not exactly . we found a boson , probably the higgs boson . '' `` what 's that ? '' `` it 's a particle . '' `` do n't you find particles all the time ? '' `` yes , but this one means that the higgs field might really exist . '' `` field ? what field ? '' `` the higgs field . it 's named after peter higgs , although many others contributed to the idea . it is n't a field , like where you grow corn , but a hypothetical , invisible kind of force field that pervades the whole universe . '' `` hmmmm , okay . if it pervades the whole universe , how come i 've never seen it ? that 's a bit strange . '' `` well , actually , it 's not that strange . think of the air around us . we ca n't see it or smell it . well , perhaps in some places we can . but we can detect its presence with sophisticated equipment , like our own bodies . so the fact that we ca n't see something just makes it a bit harder to determine whether its really there or not . '' `` alright , go on . '' `` so , we believe this higgs field is all around us , everywhere in the universe . and what it does is rather special - it gives mass to elementary particles . '' `` what 's an elementary particle ? '' `` an elementary particle is what we call particles that have no structure , they ca n't be divided , they 're the basic building blocks of the universe . '' `` i thought those were atoms . '' `` well , atoms are actually made of smaller components , protons , neutrons , and electrons . while electrons are fundamental particles , neutrons and protons are not . they are made up of other fundamental particles called quarks . '' `` sounds like russian dolls . does it ever end ? '' `` actually , we do n't really know . but our current understanding is called the standard model . in it , there are two types of fundamental particles : the fermions , that make up matter , and the bosons , that carry forces . we often order these particles according to their properties , such as mass . we can measure the masses of the particles , but we never really knew where this mass came from or why they have the masses they do . '' `` so how does this higgs field thing explain mass ? '' `` well , when a particle passes through the higgs field , it interacts and gets mass . the more it interacts , the more mass it has . '' `` ok , i kind of get that , but is it really that important ? i mean , what if there were no higgs field ? '' `` if there were no higgs field , the world would n't exist at all . there would be no stars , no planets , no air , no anything , not even that spoon or the ice cream you 're eating . '' `` oh , that would be bad . okay , but where does this higgs boson fit into things ? '' `` alright , now , you see the cherry in my shake ? '' `` can i have it ? '' `` no , not yet . we have to use it as an analogy first . '' `` oh , right , the cherry 's the higgs boson . '' `` no , not quite . the cherry is a particle moving through the higgs field , the shake . the shake gives the cherry its mass . '' `` i get it . okay , so the molecules of the shake are the higgs bosons ! '' `` well , you 're getting closer . it takes an excitation of the higgs field to produce the higgs boson . so , for example , if i were to add energy by , say , dropping this cherry in the shake , '' `` ah , then the drops that spill on the bar are the higgs bosons . '' `` almost ! the splash itself is the higgs boson . '' `` are you serious ? '' `` well , that 's what quantum mechanics teaches us . in fact , all particles are excitations of fields . '' `` okay , right . well , i kind of see why you like particle physics , it 's quite cool , strange , but cool . '' `` yeah , you could call it a bit strange , it 's not like everyday life . the higgs boson is an excitation of the higgs field . by finding the higgs boson , we know that the higgs field exists . '' `` right . so now you found it , we know this higgs field exists . you must be done . is there anything left of particle physics ? '' `` actually , we 've just begun . it 's a bit like , you know , when columbus thought he had found a new route to india . he 'd , indeed , found something new , but not quite what he was expecting . so , first , we need to make sure that the boson we found is actually the higgs boson . it seems to fit , but we need to measure its properties to be sure . '' `` how 'd you do that ? '' `` take a lot more data . this new boson lives for only a very short time before it breaks down or decays into lighter , more stable particles . by measuring these particles , you learn about the properties of the boson . '' `` and what exactly are you looking for ? '' `` well , the standard model predicts how often and in what ways the higgs boson would decay to the various , lighter particles . so we want to see if the particle we have found is the one predicted by the standard model or if it fits into other possible theoretical models . '' `` and if it fits a different model ? '' `` that would be even more exciting ! in fact , that 's how science advances . we replace old models with new ones if they better explain our observations . '' `` right , so it seems like finding this higgs boson gives a direction for exploration , a bit like that columbus guy heading west . '' `` exactly ! and this is really just the beginning . ''

what field ? '' `` the higgs field . it 's named after peter higgs , although many others contributed to the idea .

where is the higgs field located ?

imagine something small enough to float on a particle of dust that holds the keys to understanding cancer , virology , and genetics . luckily for us , such a thing exists in the form of trillions upon trillions of human lab-grown cells called hela . let 's take a step back for a second . scientists grow human cells in the lab to study how they function , understand how diseases develop , and test new treatments without endangering patients . to make sure that they can repeat these experiments over and over , and compare the results with other scientists , they need huge populations of identical cells that can duplicate themselves faithfully for years , but until 1951 , all human cell lines that researchers tried to grow had died after a few days . then a john hopkins scientist named george gey received a sample of a strange looking tumor : dark purple , shiny , jelly-like . this sample was special . some of its cells just kept dividing , and dividing , and dividing . when individual cells died , generations of copies took their place and thrived . the result was an endless source of identical cells that 's still around today . the very first immortal human cell line . gey labeled it `` hela '' after the patient with the unusual tumor , henrietta lacks . born on a tobacco farm in virginia , she lived in baltimore with her husband and five children . she died of aggressive cervical cancer a few months after her tumorous cells were harvested , and she never knew about them . so what 's so special about the cells from henrietta lacks that lets them survive when other cell lines die ? the short answer is we do n't entirely know . normal human cells have built-in control mechanisms . they can divide about 50 times before they self destruct in a process called apoptosis . this prevents the propagation of genetic errors that creep in after repeated rounds of division . but cancer cells ignore these signals , dividing indefinitely and crowding out normal cells . still , most cell lines eventually die off , especially outside the human body . not hela , though , and that 's the part we ca n't yet explain . regardless , when dr. gey realized he had the first immortal line of human cells , he sent samples to labs all over the world . soon the world 's first cell production facility was churning out 6 trillion hela cells a week , and scientists put them to work in an ethically problematic way , building careers and fortunes off of henrietta 's cells without her or her family 's consent , or even knowledge until decades later . the polio epidemic was at its peak in the early 50s . hela cells , which easily took up and replicated the virus , allowed jonas salk to test his vaccine . they 've been used to study diseases , including measles , mumps , hiv , and ebola . we know that human cells have 46 chromosomes because a scientist working with hela discovered a chemcial that makes chromosomes visible . hela cells themselves actually have around 80 highly mutated chromosomes . hela cells were the first to be cloned . they 've traveled to outer space . telomerase , an enzyme that helps cancer cells evade destruction by repairing their dna , was discovered first in hela cells . in an interesting turn of fate , thanks to hela , we know that cervical cancer can be caused by a virus called hpv and now there 's a vaccine . hela-fueled discoveries have filled thousands of scientific papers , and that number is probably even higher than anyone knows . hela cells are so resilient that they can travel on almost any surface : a lab worker 's hand , a piece of dust , invading cultures of other cells and taking over like weeds , countless cures , patents and discoveries all made thanks to henrieta lacks .

let 's take a step back for a second . scientists grow human cells in the lab to study how they function , understand how diseases develop , and test new treatments without endangering patients . to make sure that they can repeat these experiments over and over , and compare the results with other scientists , they need huge populations of identical cells that can duplicate themselves faithfully for years , but until 1951 , all human cell lines that researchers tried to grow had died after a few days .

why is it so important for scientists to have a tool like hela cells in order to study human disease ?

many elements of traditional japanese culture , such as cuisine and martial arts , are well-known throughout the world . kabuki , a form of classical theater performance , may not be as well understood in the west but has evolved over 400 years to still maintain influence and popularity to this day . the word kabuki is derived from the japanese verb kabuku , meaning out of the ordinary or bizarre . its history began in early 17th century kyoto , where a shrine maiden named izumo no okuni would use the city 's dry kamo riverbed as a stage to perform unusual dances for passerby , who found her daring parodies of buddhist prayers both entertaining and mesmerizing . soon other troops began performing in the same style , and kabuki made history as japan 's first dramatic performance form catering to the common people . by relying on makeup , or keshou , and facial expressions instead of masks and focusing on historical events and everyday life rather than folk tales , kabuki set itself apart from the upper-class dance theater form known as noh and provided a unique commentary on society during the edo period . at first , the dance was practiced only by females and commonly referred to as onna-kabuki . it soon evolved to an ensemble performance and became a regular attraction at tea houses , drawing audiences from all social classes . at this point , onna-kabuki was often risque as geishas performed not only to show off their singing and dancing abilities but also to advertise their bodies to potential clients . a ban by the conservative tokugawa shogunate in 1629 led to the emergence of wakashu-kabuki with young boys as actors . but when this was also banned for similar reasons , there was a transition to yaro-kabuki , performed by men , necessitating elaborate costumes and makeup for those playing female roles , or onnagata . attempts by the government to control kabuki did n't end with bans on the gender or age of performers . the tokugawa military group , or bakufu , was fueled by confucian ideals and often enacted sanctions on costume fabrics , stage weaponry , and the subject matter of the plot . at the same time , kabuki became closely associated with and influenced by bunraku , an elaborate form of puppet theater . due to these influences , the once spontaneous , one-act dance evolved into a structured , five-act play often based on the tenets of confucian philosophy . before 1868 , when the tokugawa shogunate fell and emperor meiji was restored to power , japan had practiced isolation from other countries , or sakoku . and thus , the development of kabuki had mostly been shaped by domestic influences . but even before this period , european artists , such as claude monet , had become interested in and inspired by japanese art , such as woodblock prints , as well as live performance . after 1868 , others such as vincent van gogh and composer claude debussy began to incorporate kabuki influences in their work , while kabuki itself underwent much change and experimentation to adapt to the new modern era . like other traditional art forms , kabuki suffered in popularity in the wake of world war ii . but innovation by artists such as director tetsuji takechi led to a resurgence shortly after . indeed , kabuki was even considered a popular form of entertainment amongst american troops stationed in japan despite initial u.s. censorship of japanese traditions . today , kabuki still lives on as an integral part of japan 's rich cultural heritage , extending its influence beyond the stage to television , film , and anime . the art form pioneered by okuni continues to delight audiences with the actors ' elaborate makeup , extravagant and delicately embroidered costumes , and the unmistakable melodrama of the stories told on stage .

before 1868 , when the tokugawa shogunate fell and emperor meiji was restored to power , japan had practiced isolation from other countries , or sakoku . and thus , the development of kabuki had mostly been shaped by domestic influences . but even before this period , european artists , such as claude monet , had become interested in and inspired by japanese art , such as woodblock prints , as well as live performance .

two eastern philosophies shaped the early development of kabuki . the first , buddhism , was used by izumo no okuni to create unique dances , which were originally used for prayers . what was the second , and in what ways did kabuki change due to its implementation ?

can you grow a human bone outside the human body ? the answer may soon be yes , but before we can understand how that 's possible , we need to look at how bones grow naturally inside the body . most bones start in a growing fetus as a soft , flexible cartilage . bone-forming cells replace the cartilage with a spongy mineral lattice made of elements like calcium and phosphate . this lattice gets harder , as osteoblasts , which are specialized bone-forming cells , deposit more mineral , giving bones their strength . while the lattice itself is not made of living cells , networks of blood vessels , nerves and other living tissues grow through special channels and passages . and over the course of development , a legion of osteoblasts reinforce the skeleton that protects our organs , allows us to move , produces blood cells and more . but this initial building process alone is not enough to make bones strong and functional . if you took a bone built this way , attached muscles to it , and tried to use it to lift a heavy weight , the bone would probably snap under the strain . this does n't usually happen to us because our cells are constantly reinforcing and building bone wherever they 're used , a principle we refer to as wolff 's law . however , bone materials are a limited resource and this new , reinforcing bone can be formed only if there is enough material present . fortunately , osteoblasts , the builders , have a counterpart called osteoclasts , the recyclers . osteoclasts break down the unneeded mineral lattice using acids and enzymes so that osteoblasts can then add more material . one of the main reasons astronauts must exercise constantly in orbit is due to the lack of skeletal strain in free fall . as projected by wolff 's law , that makes osteoclasts more active than osteoblasts , resulting in a loss of bone mass and strength . when bones do break , your body has an amazing ability to reconstruct the injured bone as if the break had never happened . certain situations , like cancer removal , traumatic accidents , and genetic defects exceed the body 's natural ability for repair . historical solutions have included filling in the resulting holes with metal , animal bones , or pieces of bone from human donors , but none of these are optimal as they can cause infections or be rejected by the immune system , and they ca n't carry out most of the functions of healthy bones . an ideal solution would be to grow a bone made from the patient 's own cells that 's customized to the exact shape of the hole , and that 's exactly what scientists are currently trying to do . here 's how it works . first , doctors extract stem cells from a patient 's fat tissue and take ct scans to determine the exact dimensions of the missing bone . they then model the exact shape of the hole , either with 3d printers , or by carving decellularized cow bones . those are the bones where all of the cells have been stripped away , leaving only the sponge-like mineral lattice . they then add the patient 's stem cells to this lattice and place it in a bioreactor , a device that will simulate all of the conditions found inside the body . temperature , humidity , acidity and nutrient composition all need to be just right for the stem cells to differentiate into osteoblasts and other cells , colonize the mineral lattice , and remodel it with living tissue . but there 's one thing missing . remember wolff 's law ? an artificial bone needs to experience real stress , or else it will come out weak and brittle , so the bioreactor constantly pumps fluids around the bone , and the pressure tells the osteoblasts to add bone density . put all of this together , and within three weeks , the now living bone is ready to come out of the bioreactor and to be implanted into the patient 's body . while it is n't yet certain that this method will work for humans , lab grown bones have already been successfully implanted in pigs and other animals , and human trials may begin as early as 2016 .

one of the main reasons astronauts must exercise constantly in orbit is due to the lack of skeletal strain in free fall . as projected by wolff 's law , that makes osteoclasts more active than osteoblasts , resulting in a loss of bone mass and strength . when bones do break , your body has an amazing ability to reconstruct the injured bone as if the break had never happened . certain situations , like cancer removal , traumatic accidents , and genetic defects exceed the body 's natural ability for repair .

why are osteoclasts , cells that break down bones , actually important in bone growth ?

[ music ] a tetrad of lunar eclipses – presented by science @ nasa for people in the united states , an extraordinary series of lunar eclipses is about to begin . the action starts on april 15th when the full moon passes through the amber shadow of earth , producing a midnight eclipse visible across north america . that night marks the beginning of a lunar eclipse tetrad a series of 4 consecutive total eclipses occurring at six month intervals . the total eclipse of april 15 , 2014 , will be followed by another on oct. 8 , 2014 , and another on april 4 , 2015 , and another on sept. 28 2015 . 'the most unique thing about the 2014-2015 tetrad is that all of them are visible for all or parts of the usa , ' says longtime nasa eclipse expert fred espenak . on average , lunar eclipses occur about twice a year , but not all of them are total . there are three types : a penumbral eclipse is when the moon passes through the pale outskirts of earth 's shadow . it 's so subtle , sky watchers often do n't notice an eclipse is underway . a partial eclipse is more dramatic . the moon dips into the core of earth 's shadow , but not all the way , so only a fraction of moon is darkened . a total eclipse , when the entire moon is shadowed , is best of all . the face of the moon turns sunset-red for up to an hour or more as the eclipse slowly unfolds . usually , lunar eclipses come in no particular order . a partial can be followed by a total , followed by a penumbral , and so on . anything goes . occasionally , though , the sequence is more orderly . when four consecutive lunar eclipses are all total , the series is called a tetrad . 'during the 21st century , there are 9 sets of tetrads , so i would describe tetrads as a frequent occurrence in the current pattern of lunar eclipses , ' says espenak . 'but this has not always been the case . during the three hundred year interval from 1600 to 1900 , for instance , there were no tetrads at all . ' the april 15th eclipse begins at 2 am eastern time when the edge of the moon first enters the amber core of earth 's shadow . totality occurs during a 78 minute interval beginning around 3 o'clock in the morning on the east coast , midnight on the west coast . weather permitting , the red moon will be easy to see across the entirety of north america . why red ? a quick trip to the moon provides the answer : imagine yourself standing on a dusty lunar plain looking up at the sky . overhead hangs earth , nightside down , completely hiding the sun behind it . the eclipse is underway . you might expect earth seen in this way to be utterly dark , but it 's not . the rim of the planet seems to be on fire ! as you scan your eye around earth 's circumference , you 're seeing every sunrise and every sunset in the world , all of them , all at once . this incredible light beams into the heart of earth 's shadow , filling it with a coppery glow and transforming the moon into a great red orb . mark your calendar for april 15th , and let the tetrad begin ! for more rare occurrences in the night 's sky , stay tuned to science.nasa.gov

'the most unique thing about the 2014-2015 tetrad is that all of them are visible for all or parts of the usa , ' says longtime nasa eclipse expert fred espenak . on average , lunar eclipses occur about twice a year , but not all of them are total . there are three types : a penumbral eclipse is when the moon passes through the pale outskirts of earth 's shadow .

on average , lunar eclipses occur how many times a year ?

to survive in this high pressured , crazy world most of us have to become highly adept at self-criticism . we learn how to tell ourselves off for our failures and for not working hard or smart enough . but so good are we at this that we 're sometimes in danger of falling prey to an excessive form of self-criticism what we might call self-flagellation a rather dangerous state which just ushers in depression and under-performance . we might simply lose the will to get out of bed . for those moments , we need a corrective . we need to carve out time for an emotional state of which many of us are profoundly suspicious . self-compassion . we 're suspicious because that sounds horribly close to self-pity but because depression and self-hatred are serious enemies of a good life , we need to appreciate the role of self-care in a good , ambitious and fruitful life . to this end we can perform what we 've called a , `` self-compassion exercise '' a structured meditation , lasting 15 minutes or so lying in bed , or perhaps a bath turn over a sequence of thoughts that interrupt and correct the flow of your worse self-accusations . for a time adopt an entire kindly perspective on your setbacks the self compassion exercise goes like this : we 're so in love with success we fail to notice the scale of the challenges we routinely set ourselves . there is nothing remotely normal about what we 've tried to achieve . we 've failed , but given the mountain we were trying to climb , the conclusion does n't have to be that we 're simply flawless . we have tricky family histories , we all do . there were things which happened to us at the hands of others which can help to explain some of our current troubles . we 're not entirely sane or well , but none of us are . we were n't well set up to carry out certain tasks it is n't wholly our fault in the here and now . from the media , you 'd think everyone was rich and famous and successful . but in reality , undramatic , quiet failure is by a huge margin the statistical norm . we should n't tear ourselves apart for not managing to be to what were in truth , awesome odds . tough , self-critical people do n't allow themselves the indulgence of believing in luck . they take responsibility for everything . they think winners make their own luck but they do n't for the most part . luck is a genuine feature of existence we 're robbing ourselves of fair concilation by believing that we 're entirely in control , and therefore entirely to blame when we crash . you are not only your achievements . status and material success are one bit of you . but there are others as well , those who loved you in childhood knew this , and in their best moments helped you to feel it . rehearse the internalized voices of all those who have been kind to you . bathe in the memory of a laugh independent of achievement . it seems it will never end that 's not the truth it 's just how a crisis feels . you need to reduce expectations to zero for a time . take each new hour as it comes , and without being banal , what you need most of all , is some rest .

we should n't tear ourselves apart for not managing to be to what were in truth , awesome odds . tough , self-critical people do n't allow themselves the indulgence of believing in luck . they take responsibility for everything .

tough , self-critical people often think that believing in luck is self-indulgent . why ? and can you give an example of how luck may play a role in a person 's ability to achieve their goals ?

on a december afternoon in chicago during the middle of world war ii , scientists cracked open the nucleus at the center of the uranium atom and turned nuclear mass into energy over and over again . they did this by creating for the first time a chain reaction inside a new engineering marvel : the nuclear reactor . since then , the ability to mine great amounts of energy from uranium nuclei has led some to bill nuclear power as a plentiful utopian source of electricity . a modern nuclear reactor generates enough electricity from one kilogram of fuel to power an average american household for nearly 34 years . but rather than dominate the global electricity market , nuclear power has declined from an all-time high of 18 % in 1996 to 11 % today . and it 's expected to drop further in the coming decades . what happened to the great promise of this technology ? it turns out nuclear power faces many hurdles , including high construction costs and public opposition . and behind these problems lie a series of unique engineering challenges . nuclear power relies on the fission of uranium nuclei and a controlled chain reaction that reproduces this splitting in many more nuclei . the atomic nucleus is densely packed with protons and neutrons bound by a powerful nuclear force . most uranium atoms have a total of 238 protons and neutrons , but roughly one in every 140 lacks three neutrons , and this lighter isotope is less tightly bound . compared to its more abundant cousin , a strike by a neutron easily splits the u-235 nuclei into lighter , radioactive elements called fission products , in addition to two to three neutrons , gamma rays , and a few neutrinos . during fission , some nuclear mass transforms into energy . a fraction of the newfound energy powers the fast-moving neutrons , and if some of them strike uranium nuclei , fission results in a second larger generation of neutrons . if this second generation of neutrons strike more uranium nuclei , more fission results in an even larger third generation , and so on . but inside a nuclear reactor , this spiraling chain reaction is tamed using control rods made of elements that capture excess neutrons and keep their number in check . with a controlled chain reaction , a reactor draws power steadily and stably for years . the neutron-led chain reaction is a potent process driving nuclear power , but there 's a catch that can result in unique demands on the production of its fuel . it turns out , most of the neutrons emitted from fission have too much kinetic energy to be captured by uranium nuclei . the fission rate is too low and the chain reaction fizzles out . the first nuclear reactor built in chicago used graphite as a moderator to scatter and slow down neutrons just enough to increase their capture by uranium and raise the rate of fission . modern reactors commonly use purified water as a moderator , but the scattered neutrons are still a little too fast . to compensate and keep up the chain reaction , the concentration of u-235 is enriched to four to seven times its natural abundance . today , enrichment is often done by passing a gaseous uranium compound through centrifuges to separate lighter u-235 from heavier u-238 . but the same process can be continued to highly enrich u-235 up to 130 times its natural abundance and create an explosive chain reaction in a bomb . methods like centrifuge processing must be carefully regulated to limit the spread of bomb-grade fuel . remember , only a fraction of the released fission energy goes into speeding up neutrons . most of the nuclear power goes into the kinetic energy of the fission products . those are captured inside the reactor as heat by a coolant , usually purified water . this heat is eventually used to drive an electric turbine generator by steam just outside the reactor . water flow is critical not only to create electricity , but also to guard against the most dreaded type of reactor accident , the meltdown . if water flow stops because a pipe carrying it breaks , or the pumps that push it fail , the uranium heats up very quickly and melts . during a nuclear meltdown , radioactive vapors escape into the reactor , and if the reactor fails to hold them , a steel and concrete containment building is the last line of defense . but if the radioactive gas pressure is too high , containment fails and the gasses escape into the air , spreading as far and wide as the wind blows . the radioactive fission products in these vapors eventually decay into stable elements . while some decay in a few seconds , others take hundreds of thousands of years . the greatest challenge for a nuclear reactor is to safely contain these products and keep them from harming humans or the environment . containment does n't stop mattering once the fuel is used up . in fact , it becomes an even greater storage problem . every one to two years , some spent fuel is removed from reactors and stored in pools of water that cool the waste and block its radioactive emissions . the irradiated fuel is a mix of uranium that failed to fission , fission products , and plutonium , a radioactive material not found in nature . this mix must be isolated from the environment until it has all safely decayed . many countries propose deep time storage in tunnels drilled far underground , but none have been built , and there 's great uncertainty about their long-term security . how can a nation that has existed for only a few hundred years plan to guard plutonium through its radioactive half-life of 24,000 years ? today , many nuclear power plants sit on their waste , instead , storing them indefinitely on site . apart from radioactivity , there 's an even greater danger with spent fuel . plutonium can sustain a chain reaction and can be mined from the waste to make bombs . storing spent fuel is thus not only a safety risk for the environment , but also a security risk for nations . who should be the watchmen to guard it ? visionary scientists from the early years of the nuclear age pioneered how to reliably tap the tremendous amount of energy inside an atom - as an explosive bomb and as a controlled power source with incredible potential . but their successors have learned humbling insights about the technology 's not-so-utopian industrial limits . mining the subatomic realm makes for complex , expensive , and risky engineering .

compared to its more abundant cousin , a strike by a neutron easily splits the u-235 nuclei into lighter , radioactive elements called fission products , in addition to two to three neutrons , gamma rays , and a few neutrinos . during fission , some nuclear mass transforms into energy . a fraction of the newfound energy powers the fast-moving neutrons , and if some of them strike uranium nuclei , fission results in a second larger generation of neutrons .

nuclear power plants benefit those people and nations who utilize the electricity they produce . however , they can also harm a larger group of people exposed to the radioactive materials they produce . the people who benefit are often not the same as the people who are at risk . what does this trade-off tell you about the desirability of nuclear energy ?

sugar is playing hide and seek with you . you 'd think it would be pretty easy for you to win , considering all the sugar in sodas , ice cream , candy , and big white bags labeled sugar . people get about half of their added sugars from those drinks and treats , so it might seem like sugar is hiding in plain sight , but like someone in the witness protection program , the other half is hidden in places you 'd least suspect . check the ingredients on ketchup , bologna , spaghetti sauce , soy milk , sports drinks , fish sticks , and peanut butter . you 'll find sugar hiding in most of those products . in fact , you 'll find added sugars in three-quarters of the more than 600,000 items available in grocery stores . but how is sugar hiding ? ca n't you just look on food labels ? it 's not that easy . just like your friend robert might go by bob , robby , rob , bobby , or roberto , added sugar has a lot of aliases . and by a lot , we do n't mean five or six , try fifty-six . there 's brown rice syrup , barley malt , demerara , florida crystals , muscovado , and , of course , high fructose corn syrup , sometimes called hfcs , or corn sugar . even sugar 's tricky nicknames have nicknames . grape or apple concentrate has the same effects on your body as its 55 sugary twins . and even though organic evaporated cane juice sounds healthy , when you evaporate it , you get sugar ! chemically speaking , it 's all the same . and even trickier , when multiple added types of sugars are used in one type of product , they get buried down in a long list of ingredients , so the sugar content might appear to be okay , but when you add them all together , sugar can be the single biggest ingredient . currently , the fda does n't suggest a recommended daily limit for sugar , so it 's hard to tell if this 65 grams in a bottle of soda is a little or a lot . but the world health organization recommends limiting sugar to just 5 % of your total calories , or about 25 grams per day . so , 65 grams is well over twice that amount . but just what is sugar ? what 's the difference between glucose and fructose ? well , both are carbohydrates with the same chemical composition of carbon , hydrogen , and oxygen . but they have very different structures and behave quite differently in our bodies . glucose is the best source of energy for nearly all organisms on earth . it can be metabolized by all organs in the body . fructose , on the other hand , is metabolized primarily in the liver , and when your liver gets overloaded with sweet , sweet fructose , the excess is metabolized to fat . fresh fruits actually contain fructose , but it 's naturally occurring and does n't cause an overload because the fiber in fruit slows its absorption . this gives your liver the time it needs to do its job . it 's sugar that makes cookies chewy and candy crunchy . it even turns bread crust a beautiful , golden brown . it 's also a great preservative ; it does n't spoil or evaporate , so the foods it 's added to are easier to store and ship long distances and tend to be cheaper . that 's why sugar is hiding everywhere . actually , it might be easier to list the foods that added sugar is n't hiding in , things like : vegetables , eggs , meats , fish , fruit , raw nuts , even your kitchen sink . simply choosing water over soda , juices , and sports drinks is a great way to avoid hidden added sugar . at the very least , try to pay attention to food labels , so you can keep your sugar intake at a healthy level . because in this game of hide and seek , every time you do n't find added sugar , you win !

people get about half of their added sugars from those drinks and treats , so it might seem like sugar is hiding in plain sight , but like someone in the witness protection program , the other half is hidden in places you 'd least suspect . check the ingredients on ketchup , bologna , spaghetti sauce , soy milk , sports drinks , fish sticks , and peanut butter . you 'll find sugar hiding in most of those products .

which has more calories and which is better for you ? an 8 ounce glass of whole milk ? or an 8 ounce glass of 1 % chocolate milk ?

how do schools of fish swim in harmony ? and how do the tiny cells in your brain give rise to the complex thoughts , memories , and consciousness that are you ? oddly enough , those questions have the same general answer : emergence , or the spontaneous creation of sophisticated behaviors and functions from large groups of simple elements . like many animals , fish stick together in groups , but that 's not just because they enjoy each other 's company . it 's a matter of survival . schools of fish exhibit complex swarming behaviors that help them evade hungry predators , while a lone fish is quickly singled out as easy prey . so which brilliant fish leader is the one in charge ? actually , no one is , and everyone is . so what does that mean ? while the school of fish is elegantly twisting , turning , and dodging sharks in what looks like deliberate coordination , each individual fish is actually just following two basic rules that have nothing to do with the shark : one , stay close , but not too close to your neighbor , and two , keep swimmming . as individuals , the fish are focused on the minutiae of these local interactions , but if enough fish join the group , something remarkable happens . the movement of individual fish is eclipsed by an entirely new entity : the school , which has its own unique set of behaviors . the school is n't controlled by any single fish . it simply emerges if you have enough fish following the right set of local rules . it 's like an accident that happens over and over again , allowing fish all across the ocean to reliably avoid predation . and it 's not just fish . emergence is a basic property of many complex systems of interacting elements . for example , the specific way in which millions of grains of sand collide and tumble over each other almost always produces the same basic pattern of ripples . and when moisture freezes in the atmosphere , the specific binding properties of water molecules reliably produce radiating lattices that form into beautiful snowflakes . what makes emergence so complex is that you ca n't understand it by simply taking it apart , like the engine of a car . taking things apart is a good first step to understanding a complex system . but if you reduce a school of fish to individuals , it loses the ability to evade predators , and there 's nothing left to study . and if you reduce the brain to individual neurons , you 're left with something that is notoriously unreliable , and nothing like how we think and behave , at least most of the time . regardless , whatever you 're thinking about right now is n't reliant on a single neuron lodged in the corner of your brain . rather , the mind emerges from the collective activities of many , many neurons . there are billions of neurons in the human brain , and trillions of connections between all those neurons . when you turn such a complicated system like that on , it could behave in all sorts of weird ways , but it does n't . the neurons in our brain follow simple rules , just like the fish , so that as a group , their activity self-organizes into reliable patterns that let you do things like recognize faces , successfully repeat the same task over and over again , and keep all those silly little habits that everyone likes about you . so , what are the simple rules when it comes to the brain ? the basic function of each neuron in the brain is to either excite or inhibit other neurons . if you connect a few neurons together into a simple circuit , you can generate rhythmic patterns of activity , feedback loops that ramp up or shut down a signal , coincidence detectors , and disinhibition , where two inhibitory neurons can actually activate another neuron by removing inhibitory brakes . as more and more neurons are connected , increasingly complex patterns of activity emerge from the network . soon , so many neurons are interacting in so many different ways at once that the system becomes chaotic . the trajectory of the network 's activity can not be easily explained by the simple local circuits described earlier . and yet , from this chaos , patterns can emerge , and then emerge again and again in a reproducible manner . at some point , these emergent patterns of activity become sufficiently complex , and curious to begin studying their own biological origins , not to mention emergence . and what we found in emergent phenomena at vastly different scales is that same remarkable characteristic as the fish displayed : that emergence does n't require someone or something to be in charge . if the right rules are in place , and some basic conditions are met , a complex system will fall into the same habits over and over again , turning chaos into order . that 's true in the molecular pandemonium that lets your cells function , the tangled thicket of neurons that produces your thoughts and identity , your network of friends and family , all the way up to the structures and economies of our cities across the planet .

the movement of individual fish is eclipsed by an entirely new entity : the school , which has its own unique set of behaviors . the school is n't controlled by any single fish . it simply emerges if you have enough fish following the right set of local rules .

what about a school of fish does emergence describe ?

in a time-lapse video , it looks like a monster coming alive . for a moment , it sits there innocuously . then , ripples move across its surface . it bulges outwards , bursting with weird boils . it triples in volume . its color darkens ominously , and its surface hardens into an alien topography of peaks and craters . then , the kitchen timer dings . your cookie is ready . what happened inside that oven ? do n't let the apron deceive you ! bakers are mad scientists . when you slide the pan into the oven , you 're setting off a series of chemical reactions that transform one substance , dough , into another , cookies . when the dough reaches 92 degrees fahrenheit , the butter inside melts , causing the dough to start spreading out . butter is an emulsion , or mixture of two substances that do n't want to stay together , in this case , water and fat , along with some dairy solids that help hold them together . as the butter melts , its trapped water is released . and as the cookie gets hotter , the water expands into steam . it pushes against the dough from the inside , trying to escape through the cookie walls like ridley scott 's chest-bursting alien . your eggs may have been home to squirming salmonella bacteria . an estimated 142,000 americans are infected this way each year . though salmonella can live for weeks outside a living body and even survive freezing , 136 degrees is too hot for them . when your dough reaches that temperature , they die off . you 'll live to test your fate with a bite of raw dough you sneak from your next batch . at 144 degrees , changes begin in the proteins , which come mostly from the eggs in your dough . eggs are composed of dozens of different kinds of proteins , each sensitive to a different temperature . in an egg fresh from the hen , these proteins look like coiled up balls of string . when they 're exposed to heat energy , the protein strings unfold and get tangled up with their neighbors . this linked structure makes the runny egg nearly solid , giving substance to squishy dough . water boils away at 212 degrees , so like mud baking in the sun , your cookie gets dried out and it stiffens . cracks spread across its surface . the steam that was bubbling inside evaporates , leaving behind airy pockets that make the cookie light and flaky . helping this along is your leavening agent , sodium bicarbonate , or baking soda . the sodium bicarbonate reacts with acids in the dough to create carbon dioxide gas , which makes airy pockets in your cookie . now , it 's nearly ready for a refreshing dunk in a cool glass of milk . one of science 's tastiest reactions occurs at 310 degrees . this is the temperature for maillard reactions . maillard reactions result when proteins and sugars break down and rearrange themselves , forming ring-like structures , which reflect light in a way that gives foods like thanksgiving turkey and hamburgers their distinctive , rich brown color . as this reaction occurs , it produces a range of flavor and aroma compounds , which also react with each other , forming even more complex tastes and smells . caramelization is the last reaction to take place inside your cookie . caramelization is what happens when sugar molecules break down under high heat , forming the sweet , nutty , and slightly bitter flavor compounds that define , well , caramel . and , in fact , if your recipe calls for a 350 degree oven , it 'll never happen , since caramelization starts at 356 degrees . if your ideal cookie is barely browned , like a northeasterner on a beach vacation , you could have set your oven to 310 degrees . if you like your cookies to have a nice tan , crank up the heat . caramelization continues up to 390 degrees . and here 's another trick : you do n't need that kitchen timer ; your nose is a sensitive scientific instrument . when you smell the nutty , toasty aromas of the maillard reaction and caramelization , your cookies are ready . grab your glass of milk , put your feet up , and reflect that science can be pretty sweet .

if you like your cookies to have a nice tan , crank up the heat . caramelization continues up to 390 degrees . and here 's another trick : you do n't need that kitchen timer ; your nose is a sensitive scientific instrument .

at what temperature does caramelization begin ?

almost 2000 years ago , the roman philosopher seneca peered at his book through a glass of water . suddenly , the text below was transformed . the words magically became clear . but it was n't until a millennium later that that same principle would be used to create the earliest glasses . today , glasses can help millions of people with poor vision due to uncorrected refractive errors . the key to understanding what that means lies with the term refraction , the ability of a transparent medium , like glass , water , or the eye to change the direction of light passing through it . the eye has two main refractive surfaces : the cornea and the lens . ideally , these surfaces work together to refract light in a way that accurately focuses light onto the retina , the layer of light-sensitive tissue at the back of the eye that works with the brain to give rise to vision . but many people develop refractive errors , either during childhood as their eyes are growing , or in later life as their eyes age . imperfections in the cornea and lens cause refracted light to be focused in front of or behind the retina , making images appear blurry . people with refractive errors can still see color , movement , and light , but the details of what they 're looking at are out of focus . people experience refractive errors in different ways , owing to differences in their eyes . in some , light refracts too much , and in others , too little . eyes with a focal point in front of the retina are called myopic , or short-sighted . they can see close objects clearly , but those far away are out of focus . but when the focus point is behind the retina , people are hyperopic , or long-sighted . for them , objects close up are unfocused , but distant objects are crystal clear . finally , some people have a cornea with a non-spherical shape that causes astigmatism , a form of out-of-focus vision that makes all objects seem blurred , whether close or far . as we age , our eyes face new challenges . when we 're young , the lens of the eye is flexible and can change shape to bring images into focus , something called accommodation . this keeps objects in focus when we shift our gaze from far to near . but as we get older , the lens becomes less flexible , and ca n't change shape when we want to look at near objects . this is called presbyopia , and it affects adults starting around the age of 40 years . myopia , hyperopia , astigmatism , and presbyopia . each of these is a refractive error . nowadays we can fix them all with glasses or contact lenses , which work by refocusing light so it strikes the retina precisely . it 's even possible to correct vision with surgery using lasers that change the shape of the cornea and alter its refractive properties . but glasses remain the most popular . by using carefully crafted lenses to steer light to exactly the right spot on the retina , a person 's clear vision can be restored . we 've come a long way since seneca 's discovery and the crude glasses of yesteryear . in 1727 , a british optician named edward scarlett developed the modern style of glasses which are kept in place with arms which hook over each ear . today 's glasses take their inspiration from that design , but they 're also much more precise and personal . each pair is tailored for an individual to bring out their unique powers of sight . so if you 're one of the 500 million people with a problem with close or far vision , or both , there 's a pair of glasses out there waiting to reveal a whole new world that 's hiding in plain view .

but it was n't until a millennium later that that same principle would be used to create the earliest glasses . today , glasses can help millions of people with poor vision due to uncorrected refractive errors . the key to understanding what that means lies with the term refraction , the ability of a transparent medium , like glass , water , or the eye to change the direction of light passing through it .

at what age do people typically start to need reading glasses ( presbyopia ) ?

in 1845 , ireland 's vast potato fields were struck by an invasive fungal disease that rapidly infested this staple crop . the effect was devastating . one million people died of famine , and over a million more were forced to leave ireland . nowadays , we avoid such agricultural catastrophes with the help of pesticides . those are a range of manmade chemicals that control insects , unwanted weeds , funguses , rodents , and bacteria that may threaten our food supply . they 've become an essential part of our food system . as populations have grown , monoculture , single crop farming , has helped us feed people efficiently . but it 's also left our food vulnerable to extensive attack by pests . in turn , we 've become more dependent on pesticides . today , we annually shower over 5 billion pounds of pesticides across the earth to control these unwanted visitors . the battle against pests , especially insects , has marked agriculture 's long history . records from thousands of years ago suggest that humans actively burned some of their crops after harvest to rid them of pests . there 's even evidence from ancient times that we recruited other insects to help . in 300 a.d. , chinese farmers specially bred ferocious predatory ants in orange orchards to protect the trees from other bugs . later , as large-scale farming spread , we began sprinkling arsenic , lead , and copper treatments on crops . but these were incredibly toxic to humans as well . as our demand for more , safer produce increased , so did the need for effective chemicals that could control pests on a grander scale . this ushered in the era of chemical pesticides . in 1948 , a swiss chemist named paul hermann müller was awarded a nobel prize for his discovery of dichlorodiphenyltrichloroethane , also known as ddt . this new molecule had unparalleled power to control many insect species until the 1950s , when insects became resistant to it . worse , the chemical actually drove dramatic declines in bird populations , poisoned water sources , and was eventually found to cause long-term health problems in humans . by 1972 , ddt had been banned in the united states , and yet traces still linger in the environment today . since then , chemists have been searching for alternatives . with each new wave of inventions , they 've encountered the same obstacle - rapid species evolution . as pesticides destroy pest populations , they leave behind only the most resistant individuals . they then pass on their pesticide-resisting genes to the next generation . that 's lead to the rise of super bugs , such as the colorado potato beetle , which is resistant to over 50 different insecticides . another downside is that other bugs get caught in the crossfire . some of these are helpful predators of plant pests or vital pollinators , so erasing them from agriculture wipes out their benefits , too . pesticides have improved over time and are currently regulated by strict safety standards , but they still have the potential to pollute soil and water , impact wildlife , and even harm us . so considering all these risks , why do we continue using pesticides ? although they 're imperfect , they currently may be our best bet against major agricultural disasters , not to mention mosquito-born diseases . today , scientists are on a quest for alternative pest control strategies that balance the demands of food production with environmental concerns . nature has become a major source of inspiration , from natural plant and fungal chemicals that can repel or attract insects , to recruiting other insects as crop bodyguards . we 're also turning to high-tech solutions , like drones . programmed to fly over crops , these machines can use their sensors and gps to carry out more targeted sprays that limit a pesticide 's wider environmental impact . with a combination of biological understanding , environmental awareness , and improved technologies , we have a better chance of finding a holistic solution to pests . chemical pesticides may never shake their controversial reputation , but with their help , we can ensure that agricultural catastrophes stay firmly in our past .

this ushered in the era of chemical pesticides . in 1948 , a swiss chemist named paul hermann müller was awarded a nobel prize for his discovery of dichlorodiphenyltrichloroethane , also known as ddt . this new molecule had unparalleled power to control many insect species until the 1950s , when insects became resistant to it .

nobel prizes are awarded for outstanding academic , cultural or scientific advances . why would the discovery of a pesticide be granted a nobel prize ?

in 1800 , the explorer alexander von humboldt witnessed a swarm of electric eels leap out of the water to defend themselves against oncoming horses . most people thought the story so unusual that humboldt made it up . but fish using electricity is more common than you might think ; and yes , electric eels are a type of fish . underwater , where light is scarce , electrical signals offer ways to communicate , navigate , and find—plus , in rare cases , stun—prey . nearly 350 species of fish have specialized anatomical structures that generate and detect electrical signals . these fish are divided into two groups , depending on how much electricity they produce . scientists call the first group the weakly electric fish . structures near their tails called electric organs produce up to a volt of electricity , about two-thirds as much as a aa battery . how does this work ? the fish 's brain sends a signal through its nervous system to the electric organ , which is filled with stacks of hundreds or thousands of disc-shaped cells called electrocytes . normally , electrocytes pump out sodium and potassium ions to maintain a positive charge outside and negative charge inside . but when the nerve signal arrives at the electrocyte , it prompts the ion gates to open . positively charged ions flow back in . now , one face of the electrocyte is negatively charged outside and positively charged inside . but the far side has the opposite charge pattern . these alternating charges can drive a current , turning the electrocyte into a biological battery . the key to these fish 's powers is that nerve signals are coordinated to arrive at each cell at exactly the same time . that makes the stacks of electrocytes act like thousands of batteries in series . the tiny charges from each one add up to an electrical field that can travel several meters . cells called electroreceptors buried in the skin allow the fish to constantly sense this field and the changes to it caused by the surroundings or other fish . the peter ’ s elephantnose fish , for example , has an elongated chin called a schnauzenorgan that 's riddled in electroreceptors . that allows it to intercept signals from other fish , judge distances , detect the shape and size of nearby objects , and even determine whether a buried insect is dead or alive . but the elephantnose and other weakly electric fish do n't produce enough electricity to attack their prey . that ability belongs to the strongly electric fish , of which there are only a handful of species . the most powerful strongly electric fish is the electric knife fish , more commonly known as the electric eel . three electric organs span almost its entire two-meter body . like the weakly electric fish , the electric eel uses its signals to navigate and communicate , but it reserves its strongest electric discharges for hunting using a two-phased attack that susses out and then incapacitates its prey . first , it emits two or three strong pulses , as much as 600 volts . these stimulate the prey 's muscles , sending it into spasms and generating waves that reveal its hiding place . then , a volley of fast , high-voltage discharges causes even more intense muscle contractions . the electric eel can also curl up so that the electric fields generated at each end of the electric organ overlap . the electrical storm eventually exhausts and immobilizes the prey , and the electric eel can swallow its meal alive . the other two strongly electric fish are the electric catfish , which can unleash 350 volts with an electric organ that occupies most of its torso , and the electric ray , with kidney-shaped electric organs on either side of its head that produce as much as 220 volts . there is one mystery in the world of electric fish : why do n't they electrocute themselves ? it may be that the size of strongly electric fish allows them to withstand their own shocks , or that the current passes out of their bodies too quickly . some scientists think that special proteins may shield the electric organs , but the truth is , this is one mystery science still has n't illuminated .

but the elephantnose and other weakly electric fish do n't produce enough electricity to attack their prey . that ability belongs to the strongly electric fish , of which there are only a handful of species . the most powerful strongly electric fish is the electric knife fish , more commonly known as the electric eel . three electric organs span almost its entire two-meter body .

which of these species is classified as a strongly electric fish ?

tattoos have often been presented in popular media as either marks of the dangerous and deviant or trendy youth fads . but while tattoo styles come and go , and their meaning has differed greatly across cultures , the practice is as old as civilization itself . decorative skin markings have been discovered in human remains all over the world , with the oldest found on a peruvian mummy dating back to 6,000 bce . but have you ever wondered how tattooing really works ? you may know that we shed our skin , losing about 30-40,000 skin cells per hour . that 's about 1,000,000 per day . so , how come the tattoo does n't gradually flake off along with them ? the simple answer is that tattooing involves getting pigment deeper into the skin than the outermost layer that gets shed . throughout history , different cultures have used various methods to accomplish this . but the first modern tattooing machine was modeled after thomas edison 's engraving machine and ran on electricity . tattooing machines used today insert tiny needles , loaded with dye , into the skin at a frequency of 50 to 3,000 times per minute . the needles punch through the epidermis , allowing ink to seep deep into the dermis , which is composed of collagen fibers , nerves , glands , blood vessels and more . every time a needle penetrates , it causes a wound that alerts the body to begin the inflammatory process , calling immune system cells to the wound site to begin repairing the skin . and it is this very process that makes tattoos permanent . first , specialized cells called macrophages eat the invading material in an attempt to clean up the inflammatory mess . as these cells travel through the lymphatic system , some of them are carried back with a belly full of dye into the lymph nodes while others remain in the dermis . with no way to dispose of the pigment , the dyes inside them remain visible through the skin . some of the ink particles are also suspended in the gel-like matrix of the dermis , while others are engulfed by dermal cells called fibroblasts . initially , ink is deposited into the epidermis as well , but as the skin heals , the damaged epidermal cells are shed and replaced by new , dye-free cells with the topmost layer peeling off like a heeling sunburn . blistering or crusting is not typically seen with professional tattoos and complete epidermal regeneration requires 2-4 weeks , during which excess sun exposure and swimming should be avoided to prevent fading . dermal cells , however , remain in place until they die . when they do , they are taken up , ink and all , by younger cells nearby , so the ink stays where it is . but with time , tattoos do fade naturally as the body reacts to the alien pigment particles , slowly breaking them down to be carried off by the immune system 's macrophages . ultraviolet radiation can also contribute to this pigment breakdown , though it can be mitigated by the use of sunblock . but since the dermal cells are relatively stable , much of the ink will remain deep in the skin for a person 's whole life . but if tattoos are embedded in your skin for life , is there any way to erase them ? technically , yes . today , a laser is used to penetrate the epidermis and blast apart underlying pigment colors of various wavelengths , black being the easiest to target . the laser beam breaks the ink globules into smaller particles that can then be cleared away by the macrophages . but some color inks are harder to remove than others , and there could be complications . for this reason , removing a tattoo is still more difficult than getting one , but not impossible . so a single tattoo may not truly last forever , but tattoos have been around longer than any existing culture . and their continuing popularity means that the art of tattooing is here to stay .

tattooing machines used today insert tiny needles , loaded with dye , into the skin at a frequency of 50 to 3,000 times per minute . the needles punch through the epidermis , allowing ink to seep deep into the dermis , which is composed of collagen fibers , nerves , glands , blood vessels and more . every time a needle penetrates , it causes a wound that alerts the body to begin the inflammatory process , calling immune system cells to the wound site to begin repairing the skin .

what structures can you find in the dermis ?

translator : andrea mcdonough reviewer : bedirhan cinar you 've probably heard of the boston tea party , something about a bunch of angry colonists dressed as native americans throwing chests of tea into the water . but the story is far more complicated , filled with imperial intrigue , corporate crisis , smuggling , and the grassroots origins of the american revolution . the first thing you need to know about tea in the 1700 's is that it was really , really popular . in england , each man , woman , and child consumed almost 300 cups of this stuff every year . and , since the english colonized america , americans were crazy about tea too . by the 1760 's , they were drinking over a million pounds of tea every year . so , when britain wanted to increase taxes on tea in america , people were not happy , mostly because they had no say in tax decisions made in london . remember that famous phrase , `` no taxation without representation '' ? the american colonists had long believed that they were not subject to taxes imposed by legislature in which they lacked representation . in fact , rather than paying the taxes , they simply dodged the tax collectors . since the east coast of america is hundreds of miles long and british enforcement was lax , about 3/4 of the tea americans were drinking was smuggled in , usually from holland . but the british insisted that parliament did have the authority to tax the colonists , especially after britain went deeply into debt fighting the french in the seven years ' war . to close the budget gap , london looked to americans , and in 1767 imposed new taxes on a variety of imports , including the american 's beloved tea . america 's response : no thanks ! they boycotted the importation of tea from britain , and instead , brewed their own . after a new bunch of british customs commissioners cried to london for troops to help with tax enforcement , things got so heated that the red coats fired on a mob in boston , killing several people , in what was soon called the boston massacre . out of the terms of the 1773 tea act , parliament cooked up a new strategy . now the east india company would sell the surplus tea directly through hand-picked consignees in america . this would lower the price to consumers , making british tea competitive with the smuggled variety while retaining some of the taxes . but the colonists saw through the british ploy and cried , `` monopoly ! '' now it 's a cold and rainy december 16 , 1773 . about 5,000 bostonians are crowded into the old south meeting house , waiting to hear whether new shipments of tea that have arrived down the harbor will be unloaded for sale . when the captain of one of those ships reported that he could not leave with his cargo on board , sam adams rose to shout , `` this meeting can do no more to save the country ! '' cries of `` boston harbor a teapot tonight ! '' rang out from the crowd , and about 50 men , some apparently dressed as native americans , marched down to griffin 's wharf , stormed aboard three ships , and threw 340 tea chests overboard . an infuriated british government responsded with the so-called coercive acts of 1774 , which , among other things , closed the port of boston until the locals compensated the east india company for the tea . that never happened . representatives of the colonies gathered at philadelphia to consider how best to respond to continued british oppression . this first continental congress supported destruction of the tea , pledged to support a continued boycott , and went home in late october 1774 even more united in their determination to protect their rights and liberties . the boston tea party began a chain reaction that led with little pause to the declaration of independence and a bloody rebellion , after which the new nation was free to drink its tea , more or less , in peace .

remember that famous phrase , `` no taxation without representation '' ? the american colonists had long believed that they were not subject to taxes imposed by legislature in which they lacked representation . in fact , rather than paying the taxes , they simply dodged the tax collectors .

why did parliament impose new taxes on the american colonists after the mid-1700s ?

fu manchu was one of the most notorious escape artists at the omaha zoo in the 1960s . but he was n't a performer , he was an orangutan . the keepers who locked his enclosure every night were baffled to find him outside the next day hanging out with friends in a tree , or sunning on the roof . only after installing cameras did they realize fu manchu had been picking the lock with a metal wire that he kept hidden under his cheek pouch . the keepers should n't have been surprised at fu manchu 's cunningness . along with our other great ape cousins , the gorillas , chimps , and bonobos , they belong to our hominidae family tree , which stretches back 14 million years . but it 's not just their striking red hair that makes orangutans unique among our cousins . as the only great apes from asia , orangutans have adapted to a life high in the rain forest canopies . many of the skills they learn are transmitted through the special bond they have with their mothers , the most extended in the animal kingdom next to humans . orangutan mothers usually give birth to one baby at a time , waiting up to eight years before having another . this gives the young , who begin as fully dependent infants , plenty of time to learn how to climb and distinguish the hundreds of plants and fruits that make up their diet . female orangutans even stay with their mothers into their teen years to learn child-rearing . as they grow up , orangutans also develop a complex set of cooperative social skills by interacting with their peers and siblings . much like ourselves , young orangutans involuntarily mimic the facial expressions and emotions of their playmates , with behaviors that closely parallel human smiling and laughter . once they finally venture out on their own , orangutans continue to develop their resourcefulness , putting the skills they 've learned into practice . adults build a new nest each night by carefully weaving twigs together , topping them with soft leaves , pillows , and blankets . this process requires dexterity , coordination , and an eye for design . orangutans also use a variety of tools to make their lives in the jungle easier . they turn branches into fly swatters and back scratchers , construct umbrellas when it rains , make gloves from leafy pads , and even use leaves as bandages to dress their wounds . but orangutan intelligence goes far beyond jungle survival . research in controlled environments has shown that orangutans are self-aware , being one of the few species to recognize their own reflections . they also display remarkable foresight , planning , and cognition . in one experiment , researchers taught an orangutan to use a straw to extract his favorite fruit soup from a box . that orangutan was later given the choice between the straw or a grape that could be eaten right away , and he chose the straw just in case he was given another box of soup . in another experiment , orangutans figured out how to reach peanuts at the bottom of long tubes by spitting water into them . while orangutans are able to pass cognitive tests with flying colors , there are certain problems that they need our help to solve . indonesia has the world 's highest rate of deforestation , and millions of acres of rain forest are burned annually to support the logging and palm oil industries . deforestation exposes the 30,000 orangutans remaining in the wild to poachers . they kill mothers so that baby orangutans can be sold as exotic pets . but fortunately , the story often does n't end here . orphans can be confiscated and given a second chance . at special forest schools , they recover from emotional trauma and continue to develop essential life skills . against all odds , these orphans demonstrate incredible resilience and readiness to learn . in malay , the word orangutan translates literally to `` the person of the forest , '' a reminder of our common lineage . and despite orangutans being some of the smartest animals on earth , outsmarting their extinction requires the creativity , empathy , and foresight that our species share .

along with our other great ape cousins , the gorillas , chimps , and bonobos , they belong to our hominidae family tree , which stretches back 14 million years . but it 's not just their striking red hair that makes orangutans unique among our cousins . as the only great apes from asia , orangutans have adapted to a life high in the rain forest canopies .

when contrasted with our other ape cousins , what is a unique feature of orangutans ?

in mythological ancient greece , soaring above crete on wings made from wax and feathers , icarus , the son of daedalus , defied the laws of both man and nature . ignoring the warnings of his father , he rose higher and higher . to witnesses on the ground , he looked like a god , and as he peered down from above , he felt like one , too . but , in mythological ancient greece , the line that separated god from man was absolute and the punishment for mortals who attempted to cross it was severe . such was the case for icarus and daedalus . years before icarus was born , his father daedalus was highly regarded as a genius inventor , craftsman , and sculptor in his homeland of athens . he invented carpentry and all the tools used for it . he designed the first bathhouse and the first dance floor . he made sculptures so lifelike that hercules mistook them for actual men . though skilled and celebrated , daedalus was egotistical and jealous . worried that his nephew was a more skillful craftsman , daedalus murdered him . as punishment , daedalus was banished from athens and made his way to crete . preceded by his storied reputation , daedalus was welcomed with open arms by crete 's king minos . there , acting as the palace technical advisor , daedalus continued to push the boundaries . for the king 's children , he made mechanically animated toys that seemed alive . he invented the ship 's sail and mast , which gave humans control over the wind . with every creation , daedalus challenged human limitations that had so far kept mortals separate from gods , until finally , he broke right through . king minos 's wife , pasiphaë , had been cursed by the god poseidon to fall in love with the king 's prized bull . under this spell , she asked daedalus to help her seduce it . with characteristic audacity , he agreed . daedalus constructed a hollow wooden cow so realistic that it fooled the bull . with pasiphaë hiding inside daedalus 's creation , she conceived and gave birth to the half-human half-bull minotaur . this , of course , enraged the king who blamed daedalus for enabling such a horrible perversion of natural law . as punishment , daedalus was forced to construct an inescapable labyrinth beneath the palace for the minotaur . when it was finished , minos then imprisoned daedalus and his only son icarus within the top of the tallest tower on the island where they were to remain for the rest of their lives . but daedalus was still a genius inventor . while observing the birds that circled his prison , the means for escape became clear . he and icarus would fly away from their prison as only birds or gods could do . using feathers from the flocks that perched on the tower , and the wax from candles , daedalus constructed two pairs of giant wings . as he strapped the wings to his son icarus , he gave a warning : flying too near the ocean would dampen the wings and make them too heavy to use . flying too near the sun , the heat would melt the wax and the wings would disintegrate . in either case , they surely would die . therefore , the key to their escape would be in keeping to the middle . with the instructions clear , both men leapt from the tower . they were the first mortals ever to fly . while daedalus stayed carefully to the midway course , icarus was overwhelmed with the ecstasy of flight and overcome with the feeling of divine power that came with it . daedalus could only watch in horror as icarus ascended higher and higher , powerless to change his son 's dire fate . when the heat from the sun melted the wax on his wings , icarus fell from the sky . just as daedalus had many times ignored the consequences of defying the natural laws of mortal men in the service of his ego , icarus was also carried away by his own hubris . in the end , both men paid for their departure from the path of moderation dearly , icarus with his life and daedalus with his regret .

when it was finished , minos then imprisoned daedalus and his only son icarus within the top of the tallest tower on the island where they were to remain for the rest of their lives . but daedalus was still a genius inventor . while observing the birds that circled his prison , the means for escape became clear .

what are some character traits that daedalus possessed ? describe how they affected his life .

acids and bases are everywhere . they 're used to make foods , soaps and detergents , fertilizers , explosives , dyes , plastics , pesticides , even paper . our stomachs are very acidic . our blood is slightly basic . our proteins are made up of amino acids , and the letters in our genetic code , those as , ts , cs , and gs , are all bases . you were probably taught how acids and bases behave on the molecular level . you were probably never taught that a long time ago , like ancient greek ago , before anyone knew about atoms or molecules , acids and bases were defined by how they behaved . acids tasted sour and corroded metal . bases felt slippery and could somehow counteract acids . when molecules dissolved in water interact , they are exchanging two main currencies with their surroundings : protons , also known as hydrogen ions , and electrons . depending on how a molecule is composed or shaped , it may be willing to donate or accept either protons or electrons with some other community member . and some molecules are far more aggressive than others when it comes to donating or accepting either currency . remember that protons are positively charged and electrons are negatively charged . so , if a molecule is willing to give up a proton , that 's not too different from it being willing to accept an electron -- either way it 's becoming more negatively charged . other molecules are willing to accept a proton or give up an electron . these are becoming more positively charged . some substances are so aggressive about donating their protons that when they get a chance , all of the molecules in a sample will dump a proton , sometimes more than one , to the surrounding water molecules . we call these strong acids . meanwhile , some compounds are so ready to accept a proton that they wo n't wait around , they 'll just rip one off water , which usually has two protons but is generous enough to hang out with just one . we call these strong bases . other acids and bases are not so strong . they may donate just a few of their protons to water or accept just a few protons from water , but most of their molecules stay exactly the same . if left alone in water , they 'll reach some equilibrium point where maybe only one out of a hundred or one out of ten thousand of their molecules has exchanged currency with water . as you might guess , we label these acids and bases weak , but in the common sense of the word , they 're not weak . the vinegar in your salad dressing that you can smell from across the room , that is a weak acid . the ammonia you spray on glass for a streak-free shine , that is a weak base . so , it does n't take much to be an active player in the chemical economy . most acid-base chemistry takes place in water , which can act as either an acid or a base , accepting deposits and enabling withdrawals like a 24-hour molecular atm . and when a proton-deposit customer , that 's an acid , and a proton-withdrawal customer , the base , shop at the same time , their net effect on water 's account may cancel out , and we call this neutralization . now , certain molecules can behave as acids or bases without water , but that 's another story . let 's end by saluting water as the resilient and fair banker for acids and bases . it 's always open for business , does n't charge interest , and will never foreclose on your molecules , which is more than i can say for [ bleep ] . waah-waah .

most acid-base chemistry takes place in water , which can act as either an acid or a base , accepting deposits and enabling withdrawals like a 24-hour molecular atm . and when a proton-deposit customer , that 's an acid , and a proton-withdrawal customer , the base , shop at the same time , their net effect on water 's account may cancel out , and we call this neutralization . now , certain molecules can behave as acids or bases without water , but that 's another story .

a proton deposit customer ( an acid ) is most similar to ________ .

[ go project films ] [ wind sounds ] [ a film by emmanuel vaughan-lee ] [ wind sounds ] [ engine sounds ] [ yukon river , alaska ] [ engine sounds ] [ engine sounds continue ] [ i 'm hungry . where 's the fish ? ] [ the yup'ik peoples have lived off king salmon for centuries . ] [ since 1998 the king salmon have been disappearing . ] [ ♪ music ♪ ] [ male speaker ] i 've been fishing all my life . in fact i used to fish with my dad . [ scraping sounds ] [ ♪ music ♪ ] i do n't know . [ ♪ music ♪ ] [ ♪ music continues ♪ ] [ ♪ music continues ♪ ] we have nine kids , thirty-three grandchildren . we 've been blessed by our children . they help us out . warm gear , life jackets , do n't forget . [ footsteps sounds ] every one of my grandkids , since they were small , they 've been with me in the camp . do n't forget your rubber gloves . but they all work , even the littlest ones . [ rustling sounds ] [ boat horn sounds ] [ ♪ music ♪ ] [ water and engine sounds ] when i was young , average fish was like thirty pounds . [ ♪ music ♪ ] but now you 're lucky if you get eighteen pounder , fifteen pound king . nobody can explain that . but they can guess . they can talk . [ ♪ music ♪ ] [ ♪ music continues ♪ ] [ fire crackling sounds ] right now for subsistence , average person can take maybe ten kings and they 're satisfied . [ fire crackling sounds ] salmon is a way of our life . i hope it does n't go away . [ ♪ music ♪ ] i remember when i was growing up , i used to hear— elders will talk . they said , `` people will change , the weather will change . '' it 's true , i see it now . there 's no stopping it . [ ♪ music ♪ ] [ ♪ music continues ♪ ] [ seagull sounds ] it 's hard . for our younger people , it 's very hard . they got ta have that money to pay for the gas . got ta have gas to go out and try to get your subsistence . if there 's no more salmon , there will be no more work , i know . [ ♪ music ♪ ] [ seagull sounds ] [ ♪ music continues ♪ ] [ seagull sounds continue ] [ ♪ music ♪ ] [ water sounds ] yeah , i take my grandchildren out fishing . i teach them how to check net and how to set net and how to use the current . [ ♪ music ♪ ] [ ♪ music continues ♪ ] [ ♪ music continues ♪ ] [ ♪ music continues ♪ ] [ ♪ music continues ♪ ] i feel good when i teach them something they can remember . [ ♪ music ♪ ] [ ♪ music continues ♪ ] because we 're not going to be around forever . we 'll be gone . [ rustling and rattling sounds ] this is how they used , long time ago , no cooking pot , they cooked it out on open fire . it sure beats cup of noodles . so far they 're okay , the grandchildren . [ ♪ music ♪ ] but we 're not there all the time to watch them . [ ♪ music ♪ ] [ ♪ music continues ♪ ] i know my grandchildren will teach their kids how to fish . they will . i know they will . [ ♪ music ♪ ] [ ♪ music continues ♪ ] [ ♪ music continues ♪ ] [ yukon kings ] [ kuigpiim taryaquii ] [ ♪ music ♪ ] [ directed by emmanuel vaughan-lee ] [ produced by dorothée royal-hedinger ] [ emmanuel vaughan-lee ] [ edited by adam loften ] [ director of photography ] [ andrew david watson ] [ music by h. scott salinas ] [ guitars : h. scott salinas ] [ matthew atticus berger ] [ cello : artyom manukyan ] [ sound design/mix by d. chris smith ] [ assistant camera : elias koch ] [ color grading : leo hallal ] [ special thanks : the waska family ] [ kwik'pak fisheries ] [ ©2012 goprojectfilms.com ]

[ since 1998 the king salmon have been disappearing . ] [ ♪ music ♪ ] [ male speaker ] i 've been fishing all my life . in fact i used to fish with my dad .

ray waska teaches his grandchildren through his words and actions not only about fishing , but about living . what lessons about life have you learned from elders in your family or community ?

what rights do people have , and where do they come from ? who gets to make decisions for others and on what authority ? and how can we organize society to meet people 's needs ? these questions challenged an entire nation during the upheaval of the french revolution . by the end of the 18th century , europe had undergone a profound intellectual and cultural shift known as the enlightenment . philosophers and artists promoted reason and human freedom over tradition and religion . the rise of a middle class and printed materials encouraged political awareness , and the american revolution had turned a former english colony into an independent republic . yet france , one of the largest and richest countries in europe was still governed by an ancient regime of three rigid social classes called estates . the monarch king louis xvi based his authority on divine right and granted special privileges to the first and second estates , the catholic clergy , and the nobles . the third estate , middle class merchants and craftsmen , as well as over 20 million peasants , had far less power and they were the only ones who paid taxes , not just to the king , but to the other estates as well . in bad harvest years , taxation could leave peasants with almost nothing while the king and nobles lived lavishly on their extracted wealth . but as france sank into debt due to its support of the american revolution and its long-running war with england , change was needed . king louis appointed finance minister jacques necker , who pushed for tax reforms and won public support by openly publishing the government 's finances . but the king 's advisors strongly opposed these initiatives . desperate for a solution , the king called a meeting of the estates-general , an assembly of representatives from the three estates , for the first time in 175 years . although the third estate represented 98 % of the french population , its vote was equal to each of the other estates . and unsurprisingly , both of the upper classes favored keeping their privileges . realizing they could n't get fair representation , the third estate broke off , declared themselves the national assembly , and pledged to draft a new constitution with or without the other estates . king louis ordered the first and second estates to meet with the national assembly , but he also dismissed necker , his popular finance minister . in response , thousands of outraged parisians joined with sympathetic soldiers to storm the bastille prison , a symbol of royal power and a large storehouse of weapons . the revolution had begun . as rebellion spread throughout the country , the feudal system was abolished . the assembly 's declaration of the rights of man and citizen proclaimed a radical idea for the time -- that individual rights and freedoms were fundamental to human nature and government existed only to protect them . their privileges gone , many nobles fled abroad , begging foreign rulers to invade france and restore order . and while louis remained as the figurehead of the constitutional monarchy , he feared for his future . in 1791 , he tried to flee the country but was caught . the attempted escape shattered people 's faith in the king . the royal family was arrested and the king charged with treason . after a trial , the once-revered king was publicly beheaded , signaling the end of one thousand years of monarchy and finalizing the september 21st declaration of the first french republic , governed by the motto `` liberté , égalité , fraternité . '' nine months later , queen marie antoinette , a foreigner long-mocked as `` madame déficit '' for her extravagant reputation , was executed as well . but the revolution would not end there . some leaders , not content with just changing the government , sought to completely transform french society -- its religion , its street names , even its calendar . as multiple factions formed , the extremist jacobins lead by maximilien robespierre launched a reign of terror to suppress the slightest dissent , executing over 20,000 people before the jacobin 's own downfall . meanwhile , france found itself at war with neighboring monarchs seeking to strangle the revolution before it spread . amidst the chaos , a general named napoleon bonaparte took charge , becoming emperor as he claimed to defend the revolution 's democratic values . all in all , the revolution saw three constitutions and five governments within ten years , followed by decades alternating between monarchy and revolt before the next republic formed in 1871 . and while we celebrate the french revolution 's ideals , we still struggle with many of the same basic questions raised over two centuries ago .

king louis appointed finance minister jacques necker , who pushed for tax reforms and won public support by openly publishing the government 's finances . but the king 's advisors strongly opposed these initiatives . desperate for a solution , the king called a meeting of the estates-general , an assembly of representatives from the three estates , for the first time in 175 years .

parisians showed their anger towards the king by :

everybody loves fireworks -- the lights , the colors , and , of course , the big boom . but the history of fireworks is n't all hugs and celebrations . long before epic fireworks displays , chemists in china invented the key ingredient that propels those bright lights into the sky . that invention was what we now call gunpowder . our story begins back in ancient china in the mid-ninth century where early chinese alchemists were trying to create a potion for immortality . instead , what they created was a flammable powder that burned down many of their homes . they quickly realized that this black powder , which they called fire medicine , was precisely the opposite of something that would make you live forever . in these early days , the chinese had n't yet figured out how to make the powder explode ; it was simply very flammable , and their armies used it to make flaming arrows and even a flamethrower . but once they figured out the right proportions of ingredients to create a blast , they began using the powder even more , creating fireworks to keep evil spirits away and bombs to defend themselves against mongol invaders . it was these mongols , most likely , who spread the invention of gunpowder across the world . after fielding chinese attacks , they learned how to produce the powder themselves and brought it with them on their conquests in persia and india . william of rubruck , a european ambassador to the mongols , was likely responsible for bringing gunpowder back to europe around 1254 . from there , engineers and military inventors created all kinds of destructive weapons . from bombs to guns to cannons , gunpowder left its mark on the world in some pretty terrible ways , in contrast to the beautiful marks it can leave in the air . so , how does black powder propel fireworks into the sky ? you might have seen old westerns or cartoons where a trail of gunpowder is lit and it leads to a large and obviously explosive barrel . once the fire gets to the barrel , a large boom occurs . but why does n't the trail itself explode ? the reason is that burning the powder releases energy and gases . while the trail is burning , these are easily released into the surrounding air . but when the gunpowder is contained within the barrel , the energy and gases can not easily escape and build up until boom ! firework canisters provide a single , upward-facing outlet to channel this explosive energy . the wick ignites the gunpowder and the energy takes the easiest exit from the canister , launching the firework high into the sky . the flame then makes its way through the firework 's encasing and the same reaction occurs high above our heads . so , while the chinese alchemists never found the compound for eternal life , they did find something that would go on to shape all of civilization , something that has caused many tragic moments in human history , and yet still gives us hope when we look up in celebration at the colorful night sky .

long before epic fireworks displays , chemists in china invented the key ingredient that propels those bright lights into the sky . that invention was what we now call gunpowder . our story begins back in ancient china in the mid-ninth century where early chinese alchemists were trying to create a potion for immortality .

which of these is not a component of gunpowder ?

remember the time you fell off your bike or bumped your head on a sharp corner ? childhood injuries are things we 'd often like to forget , but our bodies often carry the memories in the form of scars . so what are these unwanted souvenirs and why do we keep them for so long after that unintended vacation to the emergency room ? the most common place we see scars are on our skin , a patch that looks slightly different from the normal skin around it . often , this is considered an unfortunate disfigurement , while other times , deliberate scarification has been used in both traditional and modern cultures , to mark a rite of passage or simply for aesthetic decoration . but the difference is n't only cosmetic . when we look at healthy skin tissue under a microscope , we see the cells that perform various functions connected by an extracellular matrix , or ecm . this is composed of structural proteins , like collagen , secreted by specialized fibroblast cells . well-arranged ecm allows for transportation of nutrients , cell-to-cell communication , and cell adhesion . but when a deep wound occurs , this arrangement is disrupted . during the process of wound healing , collagen is redeposited at the wound site , but instead of the basket-weave formation found in healthy tissue , the new ecm is aligned in a single direction , impeding inter-cell processes , and reducing durability and elasticity . to make matters worse , the healed tissue contains a higher proportion of ecm than before , reducing its overall function . in the skin , the overabundance of collagen interferes with its original functions , like producing sweat , controlling body temperature and even growing hair . the scar tissue is fragile , sensitive to changes in temperature and sensation , and should be kept in moist environments to maximize healing . this presence of excessive fibrous connective tissue in an organ is known as fibrosis , and if that term sounds familiar , it 's because our skin is not the only organ vulnerable to scarring . cystic fibrosis is a genetic disorder that causes scarring of the pancreas , while pulmonary fibrosis is a scarring of the lungs , resulting in shortness of breath . scarring of the heart and the buildup of ecm following a heart attack can inhibit its beating , leading to further heart problems . what 's common to all these conditions is that although it retains some of the original functions , the scar tissue formed after a wound is inferior to the native tissue it replaces . however , there is hope . medical researchers are now studying what causes fibroblast cells to secrete excessive amounts of collagen and how we can recruit the body 's other cells in regenerating and repopulating the damaged tissue . by learning how to better control wound healing and the formation of scar tissue , we can utilize the multi-billion-dollar budgets currently used to address the aftermath of wounding in a much more efficient manner , and help millions of people live better and healthier lives . but until then , at least some of our scars can help us remember to avoid the sorts of things that cause them .

medical researchers are now studying what causes fibroblast cells to secrete excessive amounts of collagen and how we can recruit the body 's other cells in regenerating and repopulating the damaged tissue . by learning how to better control wound healing and the formation of scar tissue , we can utilize the multi-billion-dollar budgets currently used to address the aftermath of wounding in a much more efficient manner , and help millions of people live better and healthier lives . but until then , at least some of our scars can help us remember to avoid the sorts of things that cause them .

which of the following is not an outcome of scar formation in humans ?

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 .

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 ?

david j. thouless , f. duncan m. haldane , and j. michael kosterlitz were awarded the nobel prize in ____ 2016 “ for theoretical discoveries of topological phase transitions and topological phases of matter . ”

you probably already know everything is made up of little tiny things called atoms or even that each atom is made up of even smaller particles called protons , neutrons and electrons . and you 've probably heard that atoms are small . but i bet you have n't ever thought about how small atoms really are . well , the answer is that they are really , really small . so you ask , just how small are atoms ? to understand this , let 's ask this question : how many atoms are in a grapefruit ? well , let 's assume that the grapefruit is made up of only nitrogen atoms , which is n't at all true , but there are nitrogen atoms in a grapefruit . to help you visualize this , let 's blow up each of the atoms to the size of a blueberry . and then how big would the grapefruit have to be ? it would have to be the same size of -- well , actually , the earth . that 's crazy ! you mean to say that if i filled the earth with blueberries , i would have the same number of nitrogen atoms as a grapefruit ? that 's right ! so how big is the atom ? well , it 's really , really small ! and you know what ? it gets even more crazy . let 's now look inside of each atom -- and thus the blueberry , right ? -- what do you see there ? in the center of the atom is something called the nucleus , which contains protons and neutrons , and on the outside , you 'd see electrons . so how big is the nucleus ? if atoms are like blueberries in the earth , how big would the nucleus be ? you might remember the old pictures of the atom from science class , where you saw this tiny dot on the page with an arrow pointing to the nucleus . well , those pictures , they 're not drawn to scale , so they 're kind of wrong . so how big is the nucleus ? so if you popped open the blueberry and were searching for the nucleus ... you know what ? it would be invisible . it 's too small to see ! ok. let 's blow up the atom -- the blueberry -- to the size of a house . so imagine a ball that is as tall as a two-story house . let 's look for the nucleus in the center of the atom . and do you know what ? it would just barely be visible . so to get our minds wrapped around how big the nucleus is , we need to blow up the blueberry , up to the size of a football stadium . so imagine a ball the size of a football stadium , and right smack dab in the center of the atom , you would find the nucleus , and you could see it ! and it would be the size of a small marble . and there 's more , if i have n't blown your mind by now . let 's consider the atom some more . it contains protons , neutrons and electrons . the protons and neutrons live inside of the nucleus , and contain almost all of the mass of the atom . way on the edge are the electrons . so if an atom is like a ball the size of a football stadium , with the nucleus in the center , and the electrons on the edge , what is in between the nucleus and the electrons ? surprisingly , the answer is empty space . ( wind noise ) that 's right . empty ! between the nucleus and the electrons , there are vast regions of empty space . now , technically there are some electromagnetic fields , but in terms of stuff , matter , it is empty . remember this vast region of empty space is inside the blueberry , which is inside the earth , which really are the atoms in the grapefruit . ok , one more thing , if i can even get more bizarre . since virtually all the mass of an atom is in the nucleus -- now , there is some amount of mass in the electrons , but most of it is in the nucleus -- how dense is the nucleus ? well , the answer is crazy . the density of a typical nucleus is four times 10 to the 17th kilograms per meter cubed . but that 's hard to visualize . ok , i 'll put it in english units . 2.5 times 10 to the 16th pounds per cubic feet . ok , that 's still kind of hard to figure . ok , here 's what i want you to do . make a box that is one foot by one foot by one foot . now let 's go and grab all of the nuclei from a typical car . now , cars on average weigh two tons . how many cars ' nuclei would you have to put into the box to have your one-foot-box have the same density of the nucleus ? is it one car ? two ? how about 100 ? nope , nope and nope . the answer is much bigger . it is 6.2 billion . that is almost equal to the number of people in the earth . so if everyone in the earth owned their own car -- and they do n't -- ( cars honking ) and we put all of those cars into your box ... that would be about the density of a nucleus . so i 'm saying that if you took every car in the world and put it into your one-foot box , you would have the density of one nucleus . ok , let 's review . the atom is really , really , really small . think atoms in a grapefruit like blueberries in the earth . the nucleus is crazy small . now look inside the blueberry , and blow it up to the size of a football stadium , and now the nucleus is a marble in the middle . the atom is made up of vast regions of empty space . that 's weird . the nucleus has a crazy-high density . think of putting all those cars in your one-foot box . i think i 'm tired .

that 's crazy ! you mean to say that if i filled the earth with blueberries , i would have the same number of nitrogen atoms as a grapefruit ? that 's right !

the number of atoms in a grapefruit would be equivalent to

the sun is shining . the birds are singing . it looks like the start of another lovely day . you 're walking happily in the park , when , `` ah-choo ! '' a passing stranger has expelled mucus and saliva from their mouth and nose . you can feel the droplets of moisture land on your skin , but what you ca n't feel are the thousands , or even millions , of microscopic germs that have covertly traveled through the air and onto your clothing , hands and face . as gross as this scenario sounds , it 's actually very common for our bodies to be exposed to disease-causing germs , and most of the time , it 's not nearly as obvious . germs are found on almost every surface we come into contact with . when we talk about germs , we 're actually referring to many different kinds of microscopic organisms , including bacteria , fungi , protozoa and viruses . but what our germs all have in common is the ability to interact with our bodies and change how we feel and function . scientists who study infectious diseases have wondered for decades why it is that some of these germs are relatively harmless , while others cause devastating effects and can sometimes be fatal . we still have n't solved the entire puzzle , but what we do know is that the harmfulness , or virulence , of a germ is a result of evolution . how can it be that the same evolutionary process can produce germs that cause very different levels of harm ? the answer starts to become clear if we think about a germ 's mode of transmission , which is the strategy it uses to get from one host to the next . a common mode of transmission occurs through the air , like the sneeze you just witnessed , and one germ that uses this method is the rhinovirus , which replicates in our upper airways , and is responsible for up to half of all common colds . now , imagine that after the sneeze , one of three hypothetical varieties of rhinovirus , let 's call them `` too much , '' `` too little , '' and `` just right , '' has been lucky enough to land on you . these viruses are hardwired to replicate , but because of genetic differences , they will do so at different rates . `` too much '' multiplies very often , making it very successful in the short run . however , this success comes at a cost to you , the host . a quickly replicating virus can cause more damage to your body , making cold symptoms more severe . if you 're too sick to leave your home , you do n't give the virus any opportunities to jump to a new host . and if the disease should kill you , the virus ' own life cycle will end along with yours . `` too little , '' on the other hand , multiplies rarely and causes you little harm in the process . although this leaves you healthy enough to interact with other potential hosts , the lack of symptoms means you may not sneeze at all , or if you do , there may be too few viruses in your mucus to infect anyone else . meanwhile , `` just right '' has been replicating quickly enough to ensure that you 're carrying sufficient amounts of the virus to spread but not so often that you 're too sick to get out of bed . and in the end , it 's the one that will be most successful at transmitting itself to new hosts and giving rise to the next generation . this describes what scientists call trade-off hypothesis . first developed in the early 1980s , it predicts that germs will evolve to maximize their overall success by achieving a balance between replicating within a host , which causes virulence , and transmission to a new host . in the case of the rhinovirus , the hypothesis predicts that its evolution will favor less virulent forms because it relies on close contact to get to its next victim . for the rhinovirus , a mobile host is a good host , and indeed , that is what we see . while most people experience a runny nose , coughing and sneezing , the common cold is generally mild and only lasts about a week . it would be great if the story ended there , but germs use many other modes of transmission . for example , the malaria parasite , plasmodium , is transmitted by mosquitoes . unlike the rhinovirus , it does n't need us to be up and about , and may even benefit from harming us since a sick and immobile person is easier for mosquitoes to bite . we would expect germs that depend less on host mobility , like those transmitted by insects , water or food , to cause more severe symptoms . so , what can we do to reduce the harmfulness of infectious diseases ? evolutionary biologist dr. paul ewald has suggested that we can actually direct their evolution through simple disease-control methods . by mosquito-proofing houses , establishing clean water systems , or staying home when we get a cold , we can obstruct the transmission strategies of harmful germs while creating a greater dependence on host mobility . so , while traditional methods of trying to eradicate germs may only breed stronger ones in the long run , this innovative approach of encouraging them to evolve milder forms could be a win-win situation . ( cough ) well , for the most part .

however , this success comes at a cost to you , the host . a quickly replicating virus can cause more damage to your body , making cold symptoms more severe . if you 're too sick to leave your home , you do n't give the virus any opportunities to jump to a new host .

you have been exposed to a virus that benefits from a mobile host . make a chart describing in detail the effects of having too much , too little and just the right amount of this virus in your body . include the amount of replication , symptoms of each type , and chance of transmission .