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1iyb1z | How was construction in ancient cities prioritized? | I'm mostly interested in ancient Rome, but any insight into ancient infrastructure would be wonderful. When a new city was built, what was the general order in which people built things? In walled cities, were walls among the first things built? Did people settle in cities that were still "under construction?" Was construction in conquered/annexed cities different from those built from scratch? | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/1iyb1z/how_was_construction_in_ancient_cities_prioritized/ | {
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"Dur Sharrukin was a brand new capital city built by Sargon II from 716 BC to 706 BC. The outer walls measured 1.76 km x 1.635 km, had 157 towers and seven gates. There was a large barracks, built in the south west quarter of the city. The palace and three important temples were built on a terrace on the northern edge of the city. There was a small working class residential district near the cerimonial core of the city. However, more than eighty percent of the land inside the city wall remained undeveloped. Sargon II soon died, and the Assyrian court, which had just recently moved into Dur Sharrukin, moved to another capital city. "
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2xxynm | why do most unknown calls i receive on my home phone end up having no one on the other end? | Why would they waste their time calling? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2xxynm/eli5_why_do_most_unknown_calls_i_receive_on_my/ | {
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"They're usually from call centres where they have a machine automatically call numbers on a pre-assigned list. Then, when a voice is detected on your end, someone is connected on their end to talk to you. It saves them time, even if it does result it people going \"Huh. No one there\" and hanging up before they get a chance."
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1fl30u | Why is Zeta(0) equal to -1/2? | I am very confused.
So zeta(s) is equal to 1/(1^ s)+1/(2^ s)+1/(3^ s)+..., so if s=0 then we have 1/(1^ 0)+1/(2^ 0)+1/(3^ 0)+...=1+1+1+...= ∞, so zeta(0) should be ∞. Why is it -1/2? | askscience | http://www.reddit.com/r/askscience/comments/1fl30u/why_is_zeta0_equal_to_12/ | {
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"This is because the zeta function is not defined to be equal to that sum on the entire complex plane; it is only given by the sum you're looking at when Re(s) > 1. The Riemann Zeta function is actually defined to be the analytic continuation of the function given by the sum in the half plane Re(s) > 1.\n\nThere isn't one very easy proof of the fact that Re(0) = -1/2 without first developing some tools about the zeta function. If you're willing to assume some equations, then [Wikipedia has a clean proof](_URL_0_)."
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28ij4p | Why does the metal from meteorites have such a distinctive zig-zag pattern? | Like this: _URL_0_
or this: _URL_1_ | askscience | http://www.reddit.com/r/askscience/comments/28ij4p/why_does_the_metal_from_meteorites_have_such_a/ | {
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"That pattern, called a [Widmanstatten pattern](_URL_1_) is due to the crystallization of iron and nickel minerals in the meteorite cooling very slowly. Here, 'very slowly' means a few hundred or thousand degrees C every *million years*. This slow cooling allows for large crystals of these minerals to form. They are actually interlaced crystals of two different alloys of iron and nickel. One type basically grows within the other type. [Here's an excellent review that explains the formation](_URL_0_).\n\nThe patterns are visible when meteorites are cut, polished, and etched using nitric acid or ferric chloride. These chemicals dissolve different minerals at different rates so you can eat away at one of the alloys more than the other, giving contrast to the two regions. "
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"http://i.imgur.com/VZdMFRB.jpg"
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"http://en.wikipedia.org/wiki/Widmanst%C3%A4tten_pattern#cite_note-8"
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1m4hkw | How does parasitism between a host and a parasite of different domains work? | How can a wasp, an animal, trigger genetic changes in an oak, a plant, to form galls?
This might be a senseless question but I cannot wrap my head aroud a concept that organisms so different like an animal and a plant, or a fungus and an animal etc, are able to tinker with the genetic code af an almost completely alien life form to their advantage. | askscience | http://www.reddit.com/r/askscience/comments/1m4hkw/how_does_parasitism_between_a_host_and_a_parasite/ | {
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"They aren't really tinkering with the code so much as producing an enviornment that induces the host to do something. It's more like instigating a pearl to form using a bead than genetic engineering (though the analogy isn't perfect).",
" > This might be a senseless question but I cannot wrap my head aroud a concept that organisms so different like an animal and a plant, or a fungus and an animal etc, are able to tinker with the genetic code af an almost completely alien life form to their advantage.\n\nI have objections to two assumptions that seem implicit to that question.\n\nThe first is that animals, plants, and fungi aren't really that alien on a cellar level. All eukaryoes share the same type of ribosomes, and thus translate DNA into proteins the same way. This is even similar enough to prokaryote ribosomes that bacterial RNA can often also be transcribed.\n\nAll eukaryoes have mitochondrea that differ in little more than genetic drift.\n\nSure, there are many novel proteins in any species and the cell wall results in rather different cell division in plants, but overall plants and animals are more similar than different on a cellular level.\n\nThe second issue is that parasitism (outside of viruses) rarely involves direct modification of existing genetic code. It is usually accomplished by comparably indirect manipulation of its enzymatic expression which exploits vulnerabilities and shortcomings in cellular regulation that don't arise under normal circumstances. This is usually accomplished by the introduction of a foreign chemical substance that disrupts those regulatory processes.\n\nAn example of such a disruptive chemical would be the botulinum toxin (commonly known as botulism or botox) produced by the bacteria of the same name which degrades proteins needed for neuron functionality, leading to paralysis and sometimes death. Most parasitism similarly just prevents or perverts the functionlity of normal biological processes, rather than rewrite them entirely.",
"I don't know about wasps (and it seems like the mechanism is generally unknown), but other organisms--such as bacteria, fungi, and worms--manipulate the plant's own growth systems to induce gall formation. \n\nIn plants, growth is regulated by hormones which spread throughout the plant. Two important ones that control vertical and lateral growth are auxin and cytokinin. Invading gall-forming species often cause the plant to produce more of these hormones so that normal growth is disrupted and galls form. \n\nMany parasites don't change the genomic makeup of the plant. Some organisms produce chemicals that influence the plant to produce more hormone, and others go ahead and produce more of the hormone itself. The dramatically increased local concentration of the hormone induces gall formation. \n\nHowever, some parasitic gall-forming bacteria do change the genomic makeup of the plant host. A bacterium widely used in plant genetic engineering is named Agrobacterium. When it infects, the plant, it causes the cells to take up its bacterial DNA. Its bacterial DNA contains genes that code for increased auxin production. When the plant cell incorporates the genes, the genes are expressed and auxin is locally produced in much higher concentrations. This causes gall formation. So in short, the bacteria have genes that have a product they want the plant to produce, so they just essentially stick their genes in the plant. They don't actively change the plant cell's DNA, however. "
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pmz1a | We all used to eats boogers: what effect could/did that have? | We all used to eat them... did that have a positive effect or a negative one? Also, what, specifically, are boogers made of that made them appealing? | askscience | http://www.reddit.com/r/askscience/comments/pmz1a/we_all_used_to_eats_boogers_what_effect_coulddid/ | {
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"Unfortunately I can't find the study, but a while ago (2-3 years ago) I ran across an article suggesting that eating boogers was a pseudo-vaccination, killing whatever got caught and allowing the inert form to be ingested to create antibodies. However, due to the levels of pollution in most places, it's probably not too healthy. ",
"You swallow the mucus that holds boogers together all the time. The mucus is made in the nose and skin lining the breathing passages, and naturally drains down your throat. It has proteins in it, so they can be re-digested and used. They boogers, as you call them, are trapped particles like pollen and dust (nose hair and cilia, which are \"cell hairs\", also trap or move mucus and particles) caught up in the mucus to protect your lungs from infection. Your stomach and digestive tract are much more resistant to infection by things you breathe in, so by swallowing the mucus naturally (I'm not saying boogers here, because that's an esthetic/social issue) you pretty much neutralize its potential danger."
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4hjgas | when you jump into a cold lake (say 60°f or ~15°c) why does the water no longer feel cold after about 5 minutes? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/4hjgas/eli5_when_you_jump_into_a_cold_lake_say_60f_or/ | {
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"Your body has mechanisms in place to warm you up should you be in a cold environment. Dilated blood vessels provide a flush of warmth, and shivering also produces warmth. By doing this, your body can increase its internal temperature and keep you a bit more comfortable. Stay in too long though, and your vessels will end up constricting, because your body deems it's too cold and ends up preserving heat for your vital organs.\n\nHowever, if you're staying in that cold water for too long, it'll cool your blood and by association, the rest of your body and that's how hypothermia happens. Stay comfortable, but stay warm. Old people can die of hypothermia simply by falling onto a cold floor without getting help getting up."
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4px5ja | what's the difference between nuclear and thermonuclear? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/4px5ja/eli5_whats_the_difference_between_nuclear_and/ | {
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"Usuaully Nuclear weapons are basic uranium or plutonium based 1 stage nuclear bombs that function by triggering a single fission reaction which causes a highly radioactive material to \"break\" apart and release large ammounts of energy. \n\nThermonuclear is used to describe Fusion devices which usualy fuse Hydrogen in to helium and release energy that way, a Thermonuclear weapon uses an initial fission explosion to \"kickstart\" a 2nd stage fusion explosion. thats why Hydrogen bombs are usualy refered to as \"Thermonuclear bombs\"\n\nTL;DR\n\n- Nuclear = Fission = Breaks apart atoms to generate energy \n- Thermonuclear = Fusion = Joins Atoms from element A in to Element B to generate energy. \n",
"A nuclear fission reaction (as in a nuclear power plant and every nuclear bomb) can happen at any temperature range, since all that happens is that a neutron hits an atom of a nuclear fuel (like Pu-239), and causes a fission reaction. Nuclear bombs and powerplants work by making it more likely for neutrons to hit nuclear fuel instead of something else, and thus creating a chain reaction. A real world analogy would be a landslide or avalanche.\n\nA *thermo*nuclear fusion reaction doesn't rely on neutrons, but happens spontaneously if pressure and temperature is high enough, and the atoms are so close to one another that they can react. A thermonuclear bomb creates this condition by using a conventional nuclear bomb in a way that it squeezes the fusion fuel between two layers of uranium. It has some similarity to the way spontaneous combustion is used in a diesel engine: You expend energy to compress the air so much that it can ignite the injected diesel fuel, in the process creating far more energy than you used."
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1p7cxq | Do electric motors in cars have a limited lifespan? | The reason I'm asking is that in the near future (3/4/5+ years from now), we're going to be seeing used electric cars on the market like Teslas, Volts, etc at more reasonable price points.
Normally when we shop for internal combustion cars, drivetrain wear and engine mileage are big factors in our purchasing decisions. Electric cars on the other hand are a completely different beast. My question is: can we get away with replacing the battery pack every X amount of years and driving the car forever?
If not, what would be the expected lifespan of an electric motor used in this application? | askscience | http://www.reddit.com/r/askscience/comments/1p7cxq/do_electric_motors_in_cars_have_a_limited_lifespan/ | {
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"Not forever. Ac motors have bearings which will need periodic replacement, windings with relatively delicate insulation over many turns of thin wire, and a metal cage with a rotor. Stick all this in a bouncy box that accelerates and brakes constantly. Sure must of these issues can be minimized with good engineering but they are still issues. I've seen motors last many years but a car is a pretty tough environment with pretty harsh and variable demands. Motors will fail. I'd say ten to fifteen years of a trouble free running motor will be a good and attainable result. \n\nThis is just the motor I'm talking about all the rest of the running gear (suspension, cv's, etc) will have the same issues as a car with an internal combustion engine. \n\nSource: electrician. Been working with AC motors and speed controllers for years. \n",
"Longer lifespan costs money, in a high volume business like commercial automobiles parts are built to survive a specific age with some certainty. In my niche industry (electronics for automotive safety) the target is 20 years. Saving even a few cents per vehicle amounts to millions of dollars in mass production.\n\nThe other side of the equation is that the products usually have requirements in the form of must live for at least 20 years with less than 50% failure rate. If you use an exponential model for lifetime (common for electronics) this means that the mean time between failure is around 30 years.\n\nThe requirements and models are of course more complicated then what I describe, but that is the gist of it.",
"I don't know the details of the Tesla, or theLeaf, but most electrical motors are pretty durable, and the biggest point of failure is the bearings on the shaft. But these are usually cartridge bearings, so , replace them.\nI think the electric (pure electric) car will have a much larger lifespan than internal combustion cars.\nInternal combustion is so much more complicated. Taking a liquid fuel, mixing it with air, just right combination, and having a timed controlled explosion in a finely machined engine, made of blocks of metal, held together with gaskets in between. The fuel, the explosion, the exhaust, oil to lubricate the device, and even coolant to keep the thing under control. And most of these things can't mix, or the engine gets ruined, smokes, etc.\nSo, you don't say \"Hey, I'll just put in a new piston ring on number 3 cylinder\", because putting the machined parts together is a lot of labor. Again, not familiar with the specifics of Teslas, etc, but putting a cartridge bearing on an electric motor isn't so complicated. It's not running as hot, it doesn't have all those fluids being pumped through it like gas engines.\n"
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27stld | Were white British (and Dominion) troops' relationships with non-white troops from the colonies generally positive? | I've read a bit recently about how American segregation of troops stationed in the UK was kind of shocking and offensive to many British soldiers and civilians. I'm interested in how they got along with military personnel recruited from the empire. | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/27stld/were_white_british_and_dominion_troops/ | {
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"I've read a decent amount lately about how the UK/Dominion troops and populations didn't take too well to the American forces' practice of segregation.\n\nI am curious as to how this was reconciled with the fact that the UK maintained a far flung empire at the time that was not necessarily progressive in its treatment of the native populations of its colonies and dependencies (though, from what I understand, relatively more progressive than other European powers who had overseas territories).\n\nI'm also assuming that there had to be a decent amount of colonial troops stationed in the UK before D-Day, though I could be overestimating their presence.\n\nThis isn't meant try to force some sort of moral equivalency, just an honest inquiry.",
"Quite a few from the West Indies served as aircrew\n\n_URL_0_\n\n\nIt should be noted, that these aircrew didnt serve in segregated squadrons and they would often be the only non-white person in their crew, let alone the squadron. For example:\n\n_URL_2_\n\nOtherwise it should be noted that many colonial troops like the Indian Army, Kings African Rifles and Gurkhas had been in existance for an extended period of time and had developed their own set of loyalties and traditions. In this sense, their attitiude towards white troops (and vice versa) would have been no different to business as usual.\n\n_URL_1_\n\nActually the only major full scale mutiny by colonial troops was the Indian Rebellion of 1857 and even then substantial numbers of colonial troops remained loyal (mainly Sikhs)"
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6en6ta | the science of coffee | I love coffee but it kind of baffles me how just hot water and some ground up beans creates such a drink. What chemical process makes the drink from this? Why is it bad for my teeth if it's just hot water? Why do the grounds taste nothing like a good cup?
Thank you! | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/6en6ta/eli5_the_science_of_coffee/ | {
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"Coffee is a solution - in the same way that mixing salt with water gives you salt water, coffee is bits of coffee mixed in with water.\n\nWhen you grind a coffee bean, there are some parts of the bean that can dissolve in hot water, and other parts that can't. What you're tasting, then, is the bits that *can* dissolve into water leaving the bits that can't dissolve behind in the filter.",
"Unroasted, \"green\" coffee beans look a bit like a pale green peanut. These beans can keep for years. Once roasted, though, the clock is ticking. Flavorful compounds are fragile and decompose, they're sensitive to heat and light, or they gas out with the copious amounts of CO2 the roasted beans produce. These compounds also readily oxidize, turning into bitter compounds. You can slow down the aging by storing your roasted coffee in a vacuum container, but you can't stop it - you'll even discover your vacuum is lost as the gassing process continues. Pre-grinding coffee only accelerates the process by creating a large surface area for light, heat, and oxygen to attack.\n\nCoffee peaks at 11 hours after roasting, and is dead after a week.\n\nThe soluble compounds also oxidize at an accelerated rate when introduced to hot water, so an extended steep will start turning flavorful compounds into bitter and sour compounds. This is falsely attributed to over extraction, which is also a real thing - after all the desirable compounds are extracted, a prolonged steep will start extracting undesirable compounds. This is why a proper coffee house will brew to order instead of preparing jugs ahead of time. Even if they have something like a large coffee urn, they'll change it out after an hour.\n\nTime. Time is your enemy. Time hates your coffee, and by extension hates you. Buy your coffee from a roaster. If your roaster can't tell you when your beans were roasted, if it's not on the bag, they're too old. Get whole beans. Store them in a cool, dry, dark, air-tight container. Grind before you brew, and brew small batches. Experiment with grind sizes appropriate for the brewing method - this is why bur grinders are popular - control will lead to a consistent cup, and dialing it in will help make a better cup. Too small or too large can lead to improper extraction. If you don't like \"strong\" coffee, error on the side of using too many beans, because over-extraction from too few will lead to a bitter cup. Regardless of your brewing method, it all starts with the beans. You can buy the fanciest, most expensive whatever you want, but if you started with stale beans, you're going to end with a bad cup. And you can't make espresso at home without spending $1k for an entry level machine. There are things that make something similar to espresso, but it isn't espresso. Go to a coffee house."
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28llls | Does anyone have examples of national anthems that were later abolished/replaced? | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/28llls/does_anyone_have_examples_of_national_anthems/ | {
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"I believe the German National Anthem was during the Nazi era. \n\nThe Soviet anthem had the words replaced, but kept the rather stirring melody.\n\nS. Africa replaced \"Die Stem van Suid-Afrika\", but kept a verse of it in the new anthem.\n\nCanada stopped using God Save the Queen.\n\nCzechoslovakia's anthem was split (like everything else) right down the middle, but this is a weak example as it was originally two songs that were fused together (like everything else). "
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6ohm3e | During the Waco standoff in 1993, why did large segments of the American population rally around the leader of a doomsday cult who was sexually abusing young girls, rather than their own government? | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/6ohm3e/during_the_waco_standoff_in_1993_why_did_large/ | {
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"You said during, so I'll try to keep the focus as contemporary as possible to the siege. Nevertheless, I only found one opinion poll taken from before the lethal ending to the Waco Siege and that only polled Waco residents, a small and obviously not-representative sample of the US population. Further, in [this series of polls](_URL_0_), it's interesting to see how radically public opinion shifted against the government as the nineties progressed.\n\nTo clarify the \"large segment\" who supported David Koresh and the Branch Davidians, I found three opinion polls taken from April 1993. \n\n70% of people polled supported the government's actions at Waco, versus 27% who opposed it according to [the ABC Poll from 1993](_URL_0_). \n\n[A poll from the New York Times](_URL_3_) found 8 out of 10 Americans believed David Koresh was responsible for the deaths at Waco.\n\nAnd finally, a poll taken from the [Waco Tribune Herald (footnote 5)](_URL_1_) has only fifty percent of locals supporting government action against the Branch Davidians, though 82% supported the government's ending of the siege.\n\nAs detailed in both the CBS poll and Gore Vidal's *Decline and Fall of the American Empire* those who opposed the actions of the FBI and ATF were largely hostile to what they perceived as government overreach. They saw the Branch Davidians as harmless, \"minding their own business,\" and not doing anything that should provoke the violent repression meted out by the federal besiegers. The fact that it was families pitted against heavily armed troopers with armored personnel carriers and tanks made for pretty poor optics regardless of whose side one took. \n\nThe first, ostensible reason given by the Clinton Administration for infiltrating the BD Compound was to seize illegally held arms, a stick in the eye for Americans who hold the Second Amendment dear. When the agents assigned to this mission were repulsed and the situation began to heat up, George Stephanopoulos, the White House Communications Director changed the narrative to one of trying to save the children sequestered with their families. Against this claim, Pastor Robert McCurry points out that [this was an illegitimate use of federal force](_URL_2_) given that child protection falls under state jurisdiction. McCurry, well attuned to the limits of legitimate force, rails against what he sees as a monstrous attack by the government against its people. \n\nRemember, this is less than a year after the \"[Ruby Ridge Massacre](_URL_4_)\" during which a shootout between government agents and a family fleeing the law left a US Marshal, a mother, and a son killed. That event garnered quite a bit of sympathy for the family caught in the crossfire and among certain people, predisposed them against the kind of government \"repression\" that occurred at Waco. Both Ruby Ridge and Waco were precipitated by Firearms charges and involvement by the ATF (Bureau of Alcohol, Tobacco, and Firearms). Given the Second Amendment and the mythology of private gun ownership enabling the American Revolution and protecting \"Liberty,\" the federal government's perceived use of violence to monopolize its control of domestic firearms in these two instances rattled certain segments of the population. \n\n",
"I will attempt to explain a similar situation in a broad sense, that may illuminate why puzzling public support occurs; there are a LOT of specifics to the Waco standoff that I'm obviously not addressing; I'm just showing a related example and what was learned from it. Mods; if I'm going off the rails I will not be offended if you delete my comments.\n\nMy area of study is left-wing European terrorism of the 1970s era. The dominant group active in Europe of this time was the Red Army Faction; commonly called \"The Baader-Meinhof Group.\"\n\nTheir stated goal was to be the vanguard of a violent revolution, dedicated to retaking the German state on behalf of the people, and ushering in an era of pure socialism. Early in the history of the group they were associated with violence; the serious injury of an elderly library shot when co-leader Andreas Baader was broken out of police custody, weapons training in a Palestinian camp, shootouts with police offers.\n\nAnd while this was going on, the group was pilloried, along with most leftists, by the conservative Springer Press. Founded by ~~Lord~~ Axel Springer, the Springer Press newspapers were, far and away, the most dominant news outlets in the country, surpassing 50% newspaper readership on Sunday alone. In many ways they were the 1970s German equivalent of the Rupert Murdoch's media empire, only with a much, much larger reach.\n\nSo in June of 1971 the [Institut für Demoskopie Allensbach](_URL_1_), a very well respected market research and public opinion organization, asked Germans their thoughts on the Baader-Meinhof Group.\n\nRemember, this is a group that has injured people with guns, engaged in shootouts with German police, and spoke openly of their coming violent Revolutionary War in West Germany.\n\nThe results were remarkable. 20 percent of Germans under 30 expressed \"a certain sympathy with the group,\" and one in ten young Germans said they'd be willing to shelter a group member for the night. If you tally up all the results, 14 percent of Germans said they'd either be willing to shelter a group member or would be willing to consider it. Essentially 8 million people out of a population of 60 million were either willing to materially support a violent group with the stated goal of revolution, or were willing to consider it.\n\nNow one year later, after the group began their \"war\" in earnest, killing four US soldiers, and maiming several dozen civilians, police officers, and other soldiers over a one month period, that public support essentially ceased to exist (the entire leadership was caught over the next few weeks and imprisoned).\n\nSo what was the deal? How could so many people support this group that was so clearly embraced deadly violence? Were people truly supportive of violent revolution?\n\nMy research shows that no, people weren't necessarily supportive of violent revolution in practice. But many Germans had an extremely strong belief in Socialism. The upheavals in university campuses during the 1960s across the globe were especially notable in Germany. Students were extremely well-versed in Marxist theory. The dominant left-leaning party, the SPD, had socialist revolution a part of their party platform well into the 1950s. My point is that you had a significant part of the population where the nebulous notion of \"revolution\" was a vague end goal. So when this group comes along saying \"we will be the vanguard of this revolution,\" it was easy to express a certain support of their work, despite their occasional violence. Because this portion of the population had been primed to support the vague goal of Revolution, when asked about this group that was taking baby steps trying to fight for that revolution in the real world, it would have perhaps been more a surprise had they NOT expressed support.\n\nSo my takeaway, and how I relate this to the Waco situation (though again, this is NOT my area of study), is that at the time of the Waco standoff, it essentially was a completely unknown situation to the general public prior to the initial deadly shootings that killed several ATF agents and several Branch Davidians. Much like in Germany there was a sizable portion of the US population predisposed to opposition to the US government, the ATF, the FBI, and other agencies; particularly in light of the tragic events at Ruby Ridge the year earlier. So on the news comes word of a standoff, between a group of people, several now dead, who claim they just want to be left alone, and government agents telling stories of meth labs (later shown to be false), unlawful weapons, and stories of child sexual abuse... the people inclined to support the Davidians were just as inclined to discount any information provided by the government.\n\nAnother interesting thing happened in Germany; after the bombing campaign of May 1972--their public support completely ceased. BUT... in the coming years many of their original supporters \"returned to the fold\" to an extent. They wouldn't publicly support violence or bombings, but their support morphed into an opposition to how the government was treated the imprisoned terrorists (and the government DID treat many of the terrorists truly terribly).\n\nHow I relate this Waco is this: during the siege it was likely VERY easy to discount anything the government was saying, if you were so inclined to disbelieve them. But certainly at some point even the most hardened of these folks likely accepted that Koresh was leading a group where he and others had engaged in sexual abuse of children. But because the government had managed to kill so many of the Davidians, and because the siege was handled so poorly, it trumped any concerns they had about sexual abuse. It's not that they were dismissive of it (though likely many did feel the accusations were made up); it's just that everything else felt so much more important to them.\n\nI talked about this a bit more here: _URL_0_\n\nFurther Reading:\n\nAust, Stefan. \"The Baader-Meinhof Complex\" 1988, updated 2007\n\nEDIT: Downgraded Axel Springer from Nobleman status; thanks u/LBo87 !"
]
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"http://www.cbsnews.com/news/poll-govt-covered-up-waco/",
"http://www.stateofformation.org/2012/06/“not-the-jesus-i-love-waco-residents-perception-of-the-branch-davidian-conflict-by-janet-jensen",
"http://www.islandone.org/Politics/Waco.McCurry.html",
"http://www.nytimes.com/1993/04/22/us/death-in-waco-washington-memo-a-strategy-of-openness-aims-to-avert-backlash.html?mcubz=2",
"https://en.wikipedia.org/wiki/Ruby_Ridge?oldformat=true"
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"http://www.ifd-allensbach.de/service/english/summary.html"
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1upe0s | How did calibers in uneven numbers come about? Like 152mm, 37mm and 76mm? | Wouldnt it be easier to just use even numbers like 150, 40 and 75mm? | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/1upe0s/how_did_calibers_in_uneven_numbers_come_about/ | {
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"The general reason for these odd numbers is that they are conversions from before the metric system. 37mm is about 1.5 inches, 76mm is about 3 inches, 88mm is about 3.5 inches, 152mm is about 6 inches. Early tank and anti-tank guns are particularly prone because many were adopted from naval guns like the [US WWII 76mm] (_URL_0_). However, every country has a different specific reason for specific weapons keeping the old non-metric calibers, and I don't know enough to explain why the Soviets or Germans, for example, kept the odd calibers.",
"I'm unclear about the question. Of the two examples you give, two of them *are* even numbers. Only 37 is odd. And the examples you give of *even* numbers include one odd number...\n\nAs near as I can tell, what you mean by \"odd\" is number that are strange, and not rounded off to the nearest five or ten? Is that correct?"
]
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4if0lg | if the majority of people are right handed, why does the fork go on the left when setting a table? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/4if0lg/eli5_if_the_majority_of_people_are_right_handed/ | {
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"What are the origins of that being the case?",
"The knife requires more dexterity compares to the fork which works an anchor.",
"Because you want to be manipulating the sharp, dangerous, pointy knife with your dominant hand. Which is why the dinner knife is on the right, and that leaves the fork to be on the left. ",
"Because you are expected to pick up the fork with your left and the knife (to the right of the plate, edge in) in your right; you then pierce/hold the food with the fork while you cut with the knife.\n\nTraditions then divert depending on where you are from.\n\nSome countries you then simply place the cut morsel in your mouth with the left hand, while other countries you put down the knife, shift the fork to your right hand, then put the food in your mouth. The fork then is used further in the right hand for non-cut-needing food or is shifted back to the left for more cutting work.",
"The fork is held in the left hand when you're cutting with the knife. You cut with your right hand for a couple of reasons:\n\n1. if you're righty, then you'd embarrass the hell out of yourself when cutting with the knife using your left hand.\n\n2. someone long ago thought we ought create social rules to help people from embarrassing themselves, but really were concerned about being embarrassed _by you_. \n\nSo..after you cut using the fork to steady the food you're cutting and the knife to actually cut it, you then put your knife down, transfer the fork to your right hand and eat.",
"As a left-handed person, I find it generally inconsequential whether I use my fork in my left or right hand. I pretty much always use my left hand for knives though, because I'd prefer not to cut myself trying to use a sharp object in my non-dominant hand and risk seasoning my food with my own blood.",
"[The last two threads](_URL_0_) seem to agree with most of the replies."
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4l4wn6 | why do some people leak pee when they sneeze? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/4l4wn6/eli5_why_do_some_people_leak_pee_when_they_sneeze/ | {
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"The release of your bladder is controlled by muscles. Those muscles can, for a variety of reasons, be weakened. If those muscles are weak, a sudden jolt like a sneeze can dislodge them for a moment, releasing a small amount of pee."
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1c1ug0 | I'd want to understand how and why Scandinavia became Christianized. | It seems that Norse mythology and practices are more of a fit for the living conditions in Scandinavia at the time of conversion. Generalizing for the sake of brevity, but it seems like the Old Gods were all about strength, cunning, tenacity, fatalism, and therefore perfectly suited to the hard, dangerous, and cruel conditions of the time.
How did the missionaries manage to convince people to stop worshipping their badass gods and adopt Christianity, which idealizes traits that would be considered weak?
How do you go up to a bunch of dudes that worship Thor and Odin and convince them they're wrong and they should follow a Jewish carpenter's ideas instead?
Did the rulers convert for purely political reasons and then forced their populations to convert, or was everyone actually convinced? | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/1c1ug0/id_want_to_understand_how_and_why_scandinavia/ | {
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"I'll yield to better historians, but my understanding was that it had more to do with trade and politics than natural spiritual inclinations. By the time it happened, Scandinavia had been increasingly in contact with Christian Europe and needed commercial contacts. The era of plunder and conquest was ending as more of the Christian kingdoms became better defended from attack. It became more politically expedient to join them than beat them. \n\nIt's not as if this has no precedent in history. Christianity and Islam were sprung from pagan converts. ",
"Many very powerful kingdoms in Europe was Christian. The Scandinavians especially the magnates probably saw with envy on the Frankish kingdoms and Constantinople. I don't think they saw the good of Constantinople as \"weak\". \nIf you are polytheist it is usually easier to add one more god than it is for a monotheist. Maybe they saw it as they allied them self with yet another powerful god when they became Christians. "
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93r4g2 | I discovered this seemingly well-researched video on Christopher Columbus, and why he wasn't as bad as everyone thinks he was. How accurate is it? | _URL_0_
He makes many bold claims and contradicts to many statements I have been told numerous times. His sources seem solid, though, but I'm no historian. What do you all think? | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/93r4g2/i_discovered_this_seemingly_wellresearched_video/ | {
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"I suspect everyone who watches this will see different things. I'll defer to experts on Columbus regarding the content in the first 2/3 but can point to some red flags in the last third related to how he talks about the people indigenous to North America that make me deeply suspicious of his work. When assessing the accuracy of someone's historical claims, it's helpful to start with how they frame issues. \n\nHow he talks about \"genocide\" is an indicator that his work may be not accurate or trustworthy. His suggestion that it's a simple linguistic issue regarding intent, and not a complicated matter that speaks to power, colonization, and patterns, ignores volumes of writing, especially by Indigenous authors and historians. [Parenthetical note that Zimmerman wasn't found \"innocent.\" The jury returned not guilty verdicts on all counts.] [This](_URL_0_) explores the different arguments about the use of the word and despite 6 minutes of earnest talking-into-the-camera by what appears to be a Columbus truther, cannot be simplified it into a yes/no question. That said, the creator of the term \"genocide\" cited European interactions with North American Indigenous people as an example of the term. From the piece linked above: \n\n > Lemkin applied the term to a wide range of cases including many involving European colonial projects in Africa, New Zealand, Australia, and the Americas. A recent investigation of an unfinished manuscript for a global history of genocide Lemkin was writing in the late 1940s and early 1950s reveals an expansive view of what Lemkin termed a “Spanish colonial genocide.” He never began work on a projected chapter on “The Indians of North America,” though his notes indicate that he was researching Indian removal, treaties, the California gold rush, and the Plains wars.\n\nThe second red flag is how he presents the words and images of Native Americans. Saying it's \"weird\" to hate on Columbus immediately after showing images of Native Americans expressing their opinions about the man is troublesome. More to the point, I feel confident in concluding he did little or no research on the history of renaming the holiday, or if he did, elected to ignore what he found in order to advance his central claim. Given he establishes his ancestors didn't immigrant to America until the 20th century, he's clearly not speaking as an Indigenous person. (Which isn't required for writing about Native American history, but double-checking and researching statements when writing about historically marginalized groups is basic decency and good scholarship. And his statements wouldn't be less troublesome were he Indigenous, but a native identity would shed a different light on how he uses Native Americans' words.) Had he researched the movement, he would have easily discovered the efforts to rename the holiday came from Indigenous people and that they explicitly picked the date as a way to draw attention to their [actions](_URL_1_). He also would have discovered there is an [International Day of the World’s Indigenous People](_URL_2_) on August 9th. In effect, the Indigenous activists working to rename the date are using Columbus as a proxy for the colonization of their ancestral lands by Europeans. None of the other \"worse\" men that he mentioned have a day that's recognized as a federal holiday.\n\nFinally, Columbus didn't \"discover\" America. Every time he repeats that, even when saying it's untrue, he's undercutting any historical bona fides he may have earned earlier in the video. And no. We don't need to talk about how \"primitive or not primitive\" Native Americans were.\n\nNote: I just watched about ten minutes of the video he cites as his source for \"Native American Genocide\" which contains not only terrible history practices but straight up racism. Which doesn't bode well for the rest of the history in his video."
]
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ehqnmn | topology/topological manifold | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/ehqnmn/eli5_topologytopological_manifold/ | {
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"Topology: the study of the geometric properties of a space/surface and which properties are affected by changing that shape/space through a continuous deformation (i.e. no rips/tears and no gluing); or the rules governing a specific topological space or manifold. \n\nTopological Manifold: A surface (or group of surfaces) with given properties (such as a metric, a specific number of holes/openings, etc.) \n\nFor example, a doughnut and a coffee mug belong to the same manifold (a solid with a single hole) which can be deformed from one to the other without changing some properties. A topologist would then look at what happens during the transformation to things like distance between points and any changes to a circle (does it get bigger smaller etc.)"
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3sus9d | When did the concept of "refugees" arise? It seems that in the past if your country was at war and you were a male of fighting age you would stay. When did men start leaving their country's conflicts? Is this a modern concept or are there examples of this happening throughout history? | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/3sus9d/when_did_the_concept_of_refugees_arise_it_seems/ | {
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"This depends on your definition of 'refugees'.\n\nIn 1951, a convention was held in Geneva to give an official definition to the term, and from henceforth it was possible to declare whether a person was a refugee or not. [source: [UNHCR official site](_URL_0_) ]\n\nHowever, before that there were already large population movements caused by war, famine and other forms of destruction which would cause the peoples' homeland to be inhospitable to them.\n\nIn China, one of the earliest records of such a wide scale immigration would be during the spring autumn period, when the Yue 越 king Gou Jian 勾践 destroyed the Wu 吴 kingdom. Due to the demeaning treatment that he had suffered under the Wu king previously, Gou Jian was determined to eliminate Wu utterly. Therefore the Wu people were forced to cross the sea to the Eastern islands, which is now modern day Japan. Future contact between the Han dynasty and the Japanese islands state that the Wa 倭 people claimed direct descent from king Taibo 泰伯 of Wu, and often spoke with a Wu accent and adhered to Wu customs, further supporting the theory of them being former refugees of the Chinese Wu. [source: *the Book of Han* 汉书, *Discourse on Balance* 论衡]",
"Although the term refug*ee* isn't used, there are a number of places where peoples 'seeking cities / lands of refuge' are referenced in the Bible - whether that has merit as a historically accurate source or not, it is still a historic text in terms of age, and definitely alludes to the concept of refugees.\n\nHere is one example (to fit more in with the common modern concept of refugee, I have selected an example of *mass* movement of peoples due to war / civil instability):\n\n > Exodus 12:37-39\n > \"Now the sons of Israel journeyed from Rameses to Succoth, about six hundred thousand men on foot, aside from children. A mixed multitude also went up with them, along with flocks and herds, a very large number of livestock. They baked the dough which they had brought out of Egypt into cakes of unleavened bread. For it had not become leavened, since they were driven out of Egypt and could not delay, nor had they prepared any provisions for themselves.\"\n\nI think this qualifies, since your question is phrased to the *concept* of refugee, and not 'the first historically bulletproof accounts of actual refugee events'. :)"
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2umaj6 | In the US Civil War, how realistic is the idea that if the south had won a decisive military victory like capturing Washington, Britain and France could have been tempted to intervene on the side of the south, possibly causing a peace settlement? | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/2umaj6/in_the_us_civil_war_how_realistic_is_the_idea/ | {
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"Well, the idea that the Confederacy could ever have successfully captured Washington by storm or siege is utterly unrealistic. By 1862 Washington was likely one of the most heavily defended cities in the world, by 1864 it was the most heavily fortified city in the world. Any attempt to take it by storm would have resulted in wholesale slaughter akin to Grant's Cold Harbor battle, but in reverse, and likely much more one sided. Besieging it would have been impossible since it can be resupplied by sea if absolutely necessary and the Confederates have no way of stopping such an avenue of resupply even assuming they could encircle the city.\n\nBut I digress, your main point is about the idea of foreign intervention and assuming a hypothetical southern victory on northern soil. This would greatly depend on what year your talking. If 1862, it's possible, France did want to intervene on the side of the Confederates and intimated as much to the diplomats Davis sent. However, they were unwilling to act without a British declaration of war, and it is difficult to gauge how likely such an intervention ever was. Had they won Antietam, it is possible, but following that defeat they never had a realistic chance of achieving foreign support until victory for the Confederacy was certain and by that point what need would they have for such support. \n\nYou might be wondering why I don't include Gettysburg or anything following 1862 in my belief and that's rather simple. Had the Confederacy won at Gettysburg consider the situation on July 4, yes you've just won a \"victory\", but you've also lost 25,000 men, you're still outnumbered, and you can't possibly assail northern cities. To the north you're blocked by a river and the difficulties of crossing such a river. To the south you have only Washington and if you couldn't besiege it when you had 75,000 men you certainly can't now. You've lost a 1/3 of your army and remain deep in enemy territory, now what. Wait, hope the Union after 2 1/2 years just gives in, cause Lincoln wouldn't have and he was still president no matter public opinion. Oh, and about that, you're victory is about to be tempered by the fact that on the same day you won Vicksburg and some 35,000 Confederates just surrendered and the South out in the West is in full retreat. So the situation from your perspective, or even Union newspapers, hysterical at the loss and the mystique of Lee may not change. But in the eyes of the world you won a major battle and then lost a major battle and in doing so lost 60,000 men that you could not afford to lose. The public opinion in England was never high, why would it change now that you just went 1-1 in major battles, from their perspective all you did was just offset by what Grant just did and from a purely strategical sense to the military minds of England, Grant's victory was far more significant. Everyone in the South knew it too and Lee's loss, far from being the injury was merely the salt in the wound. It's also uncertain whether immediate intervention by the British or French would have caused an immediate peace settlement. It takes time to mobilize your forces and get ready for a war, the U.S. even after a loss at Gettysburg would have had a 6 month window before having to worry about British or French troops. In that time the South's fortunes out west got worse not better. Ultimately even as early as 62 such an idea was relatively unlikely, by 63 it was far fetched, and by 64 it was bordering on delusional."
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jubj4 | Violations of the equivalence principle? | _URL_1_
_URL_0_
Is this credible? What does it mean if the equivalence principle really is violated? Does it mean something to unification like the Ars Technica article claims? Why does the spam filter not like me? | askscience | http://www.reddit.com/r/askscience/comments/jubj4/violations_of_the_equivalence_principle/ | {
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"Spammy is a grumpy old man who has a taste for good submissions. He eats them up. ",
" > Is this credible?\n\nYes, quite. It's a nice paper.\n\n > What does it mean if the equivalence principle really is violated?\n\nAbsolutely nothing. The equivalence principle rests on the principle of locality, and it holds whenever that principle is in effect. But the principle of locality is an approximation; it's violated by certain phenomena in both ordinary \"first quantisation\" mechanics and in \"second quantisation\" field theory. If locality doesn't hold, the equivalence principle doesn't either … which is less a *violation* of equivalence as it is a demonstration of the fact that equivalence depends on locality, which we knew already.\n\nNo, the interesting thing about this paper isn't that equivalence is violated when locality is violated. The interesting thing is that it's possible to *restore equivalence* even without locality. As the gravitational field gets stronger — that is, as you get closer to the event horizon of a black hole *that's only present in the paper to be the source of a gravitational field of arbitrary strength so please let's not turn this into another godawful black hole party* — the apparent violation of equivalence vanishes. *That's* interesting, and serves as yet more evidence in favour of the notion that quantum field theory and general relativity already, separately, comprise a compete quantum theory of gravity; we just have to work out the details.\n\nInsultingly condescending summary: The violation of equivalence is expected. The *restoration* of equivalence in the strong-field limit isn't expected, and comes as a pleasant surprise.",
"Only minimally coupled **scalar** matter falls along geodesics, which is what the equivalence principle claims. Even fermions which were minimally coupled would not follow geodesics, because they \"feel\" the curvature (technically: they couple to the spin connection and end up moving according to the Papapetrou equation, which includes spin). Same story for vector fields.\n\nNon-minimally coupled matter definitely doesn't satisfy the equivalence principle.\n\nNow, think about what unification means: gravity is part of something bigger. That bigger thing must symmetry-break to yield gravity and particles/fields. Therefore you expect some direct coupling between gravity and some of those particles/fields. That's what happens in electroweak symmetry breaking: the W bosons are coupled to the photon. So unification naturally suggests that there are non-minimally coupled matter fields.\n\nSo we expect equivalence principle violation.",
"Spammy is a grumpy old man who has a taste for good submissions. He eats them up. ",
" > Is this credible?\n\nYes, quite. It's a nice paper.\n\n > What does it mean if the equivalence principle really is violated?\n\nAbsolutely nothing. The equivalence principle rests on the principle of locality, and it holds whenever that principle is in effect. But the principle of locality is an approximation; it's violated by certain phenomena in both ordinary \"first quantisation\" mechanics and in \"second quantisation\" field theory. If locality doesn't hold, the equivalence principle doesn't either … which is less a *violation* of equivalence as it is a demonstration of the fact that equivalence depends on locality, which we knew already.\n\nNo, the interesting thing about this paper isn't that equivalence is violated when locality is violated. The interesting thing is that it's possible to *restore equivalence* even without locality. As the gravitational field gets stronger — that is, as you get closer to the event horizon of a black hole *that's only present in the paper to be the source of a gravitational field of arbitrary strength so please let's not turn this into another godawful black hole party* — the apparent violation of equivalence vanishes. *That's* interesting, and serves as yet more evidence in favour of the notion that quantum field theory and general relativity already, separately, comprise a compete quantum theory of gravity; we just have to work out the details.\n\nInsultingly condescending summary: The violation of equivalence is expected. The *restoration* of equivalence in the strong-field limit isn't expected, and comes as a pleasant surprise.",
"Only minimally coupled **scalar** matter falls along geodesics, which is what the equivalence principle claims. Even fermions which were minimally coupled would not follow geodesics, because they \"feel\" the curvature (technically: they couple to the spin connection and end up moving according to the Papapetrou equation, which includes spin). Same story for vector fields.\n\nNon-minimally coupled matter definitely doesn't satisfy the equivalence principle.\n\nNow, think about what unification means: gravity is part of something bigger. That bigger thing must symmetry-break to yield gravity and particles/fields. Therefore you expect some direct coupling between gravity and some of those particles/fields. That's what happens in electroweak symmetry breaking: the W bosons are coupled to the photon. So unification naturally suggests that there are non-minimally coupled matter fields.\n\nSo we expect equivalence principle violation."
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3osfy2 | how come most 3d games render at 60 fps while it takes a few seconds to render a textureless cube in blender? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/3osfy2/eli5_how_come_most_3d_games_render_at_60_fps/ | {
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"The answer depends on what you're doing in Blender. Most likely, it's because you are using a different kind of rendering. When rendering a scene, there are a bunch of computations that *can* be done. 3D games have a (mostly) fixed set of computations they perform, and they're tuned for efficiency. Graphics software like Blender allows you to do a lot of other computations - and the defaults are usually tuned for resulting image quality, not efficiency.\n\nYou won't notice much difference in the quality of the output when you're looking at a textureless cube, but that doesn't mean that Blender can skip all of the computations (though it can certainly skip some).\n\nAnother part of the delay can be in startup time. 3D games load a bunch of resources before you get to play. Blender may be doing similar loading when you tell it to render the scene.\n\nThere are a lot of \"may\" answers here because software is complex, and it depends on what games you're comparing to - and on the current implementation details of Blender.",
"There are two ways to render graphics on the screen. \n\n[Rasterization](_URL_0_) - Which is used in video games. The very simple version of this is the world is made up of triangles and all you have to do is figure out if a triangle is visible and if a pixel is in the triangle or not. Many graphics cards have electronics deigned to do this over and over again very quickly. Compare this with...\n\n[Ray Tracing](_URL_3_) - Which is used for static 3D rendering. This **calculates the path light travels for every pixel on your screen** back to the light source. The objects don't have to be triangles and are often expressed as mathematical solids. This gives you, for all intents an purposes, unlimited resolution and detail depending on how much time and CPU power you want to throw at it. Because ray tracers use complex math, the CPU brute-forces the tracing calculations. In fact, with bender, when doing ray tracing, you don't use any of the 3D capability of your graphics card at all. \n\nUpshot:\n\nRasterizer: \"Hey 3D card, draw and fill 532 triangles the make that make up this [isohedron](_URL_2_) and texture it to make it look like sphere \n\nRay Tracer: \"Hey CPU calculate how light will reflect on a [sphere](_URL_1_) of a volume of 4/3*πr^3\"\n\nOne take much more time then the other, but it also make it much more realistic at infinite scales.",
"I have very limited knowledge in this but I know a thing or two. I have used blender for 3 years and read up on articles. Think about it. If you looked at renders vs how games look, you can see that renders have better quality where as games tend to be faster. The game engine was built more for speed while the rendering engine was built more for quality. Games are pre-calculated while renders have much, much, much more things to put into the scene, such as lighting, global illumination, if animation, then physics. Also, games, instead of having more hi-detailed models, they \"bake\" the extra details to textures to make it faster but it has lower quality. \nHere are some good articles: _URL_1_\n\n_URL_2_\n\nSo in conclusion, games render more faster because of pre-calculated geometry and use techniques to achieve faster and mediocre render while 3D rendering software uses an engine that renders everything and doesn't have these techniques since it gives lower quality, thus the quality is better but longer in 3D rendering software. \n\n**Edit**:This is also why renders look SOOOOOOOOOOOOOOOOOO much better!!!!!!!!! Seriously search up 3d Renders. Also, when you talk about a texture-less cube, that's simply due to lighting, reflection and you graphics card. Even though you graphics card is good at rendering games, it may not be good at rendering 3D objects in 3D modelling software. Another article on graphics card for games vs render: _URL_0_ \n\n*Note: I would highly recommend reading the article links instead of taking my word for it :)",
"While others have answered, I'll simplify it a bit more for Eli5.\n\nVideogames take a LOT of shortcuts in lighting, use a lot smaller and simpler textures and filters and models. A lot of textures are pre-shaded for ambient occlusion, for example. Ambient occlusion is not so much a shadow, but when things are closer together and without a direct light source(eg a cloudy day) they're darker, this is very resource heavy and you don't typically see much actual occlusion in video games, and when you do it is quite rough or simple.\n\nIf you want to make a comparison to music, it would be a kazoo vs a symphony.\n\nIn the case of the blank cube and blender, you're also dealing with what is likely a much older render technique that puts a lot of effort into an accurate shadow cast upon a different object. Your shadows are going to be born of light sources in a way that more closely resembles reality by quite a bit.\n\nA lot of what video games do is just enough to deliver the impression, and the difference between them and a good 3d render really show up under scrutiny."
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[],
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"https://en.wikipedia.org/wiki/Rasterisation",
"https://en.wikipedia.org/wiki/Ray_tracing_%28graphics%29#/media/File:Recursive_raytrace_of_a_sphere.png",
"http://mft-dev.dk/wp-content/uploads/2014/05/icosahedron_frame_sub3.gif",
"https://en.wikipedia.org/wiki/Ray_tracing_%28graphics%29"
],
[
"https://www.reddit.com/r/techsupport/comments/zs1ct/can_someone_explain_the_real_difference_between/",
"https://www.quora.com/Why-does-it-take-minutes-to-render-a-scene-in-3ds-Max-or-Maya-etc-but-games-seem-to-render-seemingly-on-the-fly",
"http://gamedev.stackexchange.com/questions/82816/why-are-gaming-graphics-not-as-beautiful-as-animated-movies"
],
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6ajfcq | how do lithium ion batteries work? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/6ajfcq/eli5how_do_lithium_ion_batteries_work/ | {
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"A lithium ion battery uses charged lithium particles (ions) to move electricity from one end of the battery to another. As energy leaves the battery, these lithium ions move from the negative side of the battery to the positive side, forming a conductive lithium layer that releases electricity. When all the ions are on the positive side of the battery, the battery is spent and no longer releases electricity. When the battery is put in a charger, the sides flip temporarily, and the addition of electrical energy to the lithium causes the ions to move back to the negative side of the battery, making the battery ready for use again.\n\nBecause of these properties, lithium ion batteries are among the more common rechargeable batteries for home electronic use. "
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22hkqx | i turned on my old guitar amp with nothing plugged in and it started playing a radio station. how is this happening? | It's an old Crate guitar amplifier. Could it be a loose wire somehow acting as an antenna? Any ideas? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/22hkqx/eli5_i_turned_on_my_old_guitar_amp_with_nothing/ | {
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"Radio waves are stupid easy to pick up on any basic consumer amplifier. I've picked up radio stations on PC speakers before. Somewhere along the lines, the radio signal is inadvertently translated to an electrical signal that your system can amplify. You don't need a loose wire; just an unshielded system.\n\nAdding to that, I think the FCC mandates that consumer electronics must accept radio interference.",
"Radios have amplifiers as part of how they convert radio waves to sound via a speaker. Unshielded amplifiers can be excited (made to produce a signal) due to a strong RF signal passing through them. wires leading to an amplifier stage or even the amp circuitry itself can act as the antenna in this case. What has likely happened is either you have moved to a location closer to a transmitter (radio tower) or a transmitter near to your location has either upped its power since last you used this unit or perhaps it is operating on a new frequency. Any cheap AM/FM radio in a house near a transmitter will play the signal of a nearby powerful transmitter. As will cordless phones and other items with amplifiers. ",
"OP, your question makes me want to build a radio. I haven't played with a soldering iron in six or seven years.",
"Interference, My father had (has?) a very cheap clock radio that picked aeroplane radio traffic as it flew overhead.",
"To convert high frequency Radio Waves to frequencies that you can hear, you need a \"Detector\". \n\nThe simplest Detector is a Diode of some kind. Years ago people built Crystal sets that used a piece of Galena and a fine wire (called a Cat's Whisker) as a Detector.\n\nAny well designed electronic equipment is relatively immune to radio waves, but some cheap gear can pick it up because it is poorly shielded and something inside is acting as a Detector.\n\nWhen CB radio first came out, Radio Interference was a nightmare because there was so much rubbish electronic gear around, especially early TV sets. These days the manufactures are much more aware of the problem and tend to not cut corners so much."
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d1eos8 | what happens with the intellectual properties of a company when they close down? | Let's say The Walt Disney Company somehow went bankrupt and closed down and all movies, plushies and toys stop being made.
& nbsp;
What happens with the things that already exist? Will the ideas enter the public domain or will they be given to someone? Could they be used and distributed freely? If not, who will manage them? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/d1eos8/eli5_what_happens_with_the_intellectual/ | {
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"It gets sold off/liquidated, like physical assets (to take your example further, Disneylands, corporate headquarters, and other things like that).",
"Rights, like intellectual property rights, only really matter if there is someone to assert them. If no one purchases the rights, then they might as well be in the public domain, as no one will have any standing to file lawsuits or other actions against any infringers."
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51crhp | why do you see so many saabs and other out of production cars in movies? | Maybe it's because I've owned one before but, I just see an inordinate amount of Saabs, Pontiacs, and Saturns in movies. Is this a cost cutting thing or is there something else behind it? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/51crhp/eli5_why_do_you_see_so_many_saabs_and_other_out/ | {
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"Those brands are/were all owned by GM, and GM has made it a point of pride that their vehicles have been showcased in many motion pictures. What you're seeing is product placement coupled with favorable rental rates for fleet vehicles to achieve that effect."
]
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ahsaz5 | how does a bike stay up when at faster speeds but will fall over when not going fast enough? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/ahsaz5/eli5_how_does_a_bike_stay_up_when_at_faster/ | {
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"The gyroscopic forces created by the wheels mass cause the wheel to fix itself on a plane in turn overcoming to forces of gravity stopping it just falling over",
"Generally bikes have handlebars which have a centre of mass infront of their pivot. Meaning if you lean the bike to the left the handlebars will turn left. This has the effect of making the bike turn left and when it turns left the body of the bike is thrown outside of the turn just like in a car when going round a corner. Then it leans to the right and the cycle repeats. Then your brain helps a bit too. If you push your bike fast with no one on it will go upright for a while however if you tie the handle bars so they can't turn it will fall over just as fast as if you just let it go stationary. \n\n\nAnother interesting fact is this causes your steering to be inverted when going at speed. If you can cycle with no hands you can try this by cycling with no hands and using one finger to push your handlebars to the left you'll find the bike will lean over to the right and turn right."
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698zak | what is infrasound and how can it cause panic attacks in humans? | I'm reading about the Dylatov Pass Incident and the theory of infrasound is interesting to me but I don't understand what it is. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/698zak/eli5_what_is_infrasound_and_how_can_it_cause/ | {
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"Human hearing works for tones in the frequency range of 20hz-20000hz. Everything below that is called infrasound, everything above is called ultrasound. \n\nThe resonant frequencies of a lot of human organs happen to be in the infrasound range, so a loud/powerful enough tone can cause them to vibrate strongly, resulting in discomfort and nausea. "
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dxl1yc | what would happen to a person when they cannot afford payment to a loan/debt. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/dxl1yc/eli5_what_would_happen_to_a_person_when_they/ | {
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"In the US, they may be able to file for bankruptcy protection, discharging the debt if the person has no way of paying the debt (except for selling off essential assets).",
"This varies widely by what state you live in and what kind of debt.. Business debt, mortgages and other standard loans can usually be handled through bankruptcy. Student loans will haunt you until you die and then dig you up and demand payment. Go murica.",
"They default on a loan which means they can't pay it back, they may have to declare bankruptcy. Their credit gets ruined and for most loans the credit bereau is told to basically just forget about the loan and take the loss. This is worst case\n\n\nIf you just miss a payment on a loan then you get a ding to your credit for non-payment however a single non-payment from a late payment won't be too damaging and can even potentially removed from your credit history in some circumstances.\n\n\nIn general, credit bereaus will try to work with people to have lower payments that they can afford because they would rather have a loan take longer to be repaid than to take the loss."
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60r3vt | how can a tiny amount of toxic chemical affect a person's entire body? | [deleted] | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/60r3vt/eli5_how_can_a_tiny_amount_of_toxic_chemical/ | {
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"Toxicity is determined by the dose and the rout of administration. Some substances are highly toxic in small quantities (like ricin and cyanide) while others take large quantities to have negative physiological effects (like table salt or even water). A substance doesn't need to be toxic to all tissues in the body, just enough tissues to cause problems. Cyanide, for example, interrupts cellular respiration (basically the creation of ATP, or the energy cells use to function). By blocking this, the cells deplete their energy quickly and die off. \n\n",
"Let's do some math. Methanol is lethal at a dose of 1-2 mL/kg. So for an 80kg person, say 2mL/kg dose to be on the safe side (or dangerous, as it were) and that gives a dose of 160mL or 5.4 oz. This dose contains 2.38 x 10^24 molecules of methanol. If you have millions of cells, that's still on the order of 10^18 molecules per cell or billions of billions.\n\nEDIT: There are roughly 3.72 trillion (human) cells in the body, so that bumps it down from billions of billions to only trillions of molecules per cell."
]
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fhbspc | why the rear wheel in buses and trucks is close to centre? | [deleted] | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/fhbspc/eli5_why_the_rear_wheel_in_buses_and_trucks_is/ | {
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"It's to increase manouverability. The further back the rear wheels are, the longer the wheelbase of the vehicle is, and therefore the wider any turns it will make will be. \n\nIf you move the rear wheels towards the front of the bus, then the bus can swing into tighter turns. The tradeoff is the back end of the bus can swing out now, whereas if the wheels are at the back, that can't happen.",
"The longer the wheelbase, the wider the turning circle. A wider turning circle makes negotiating corners harder."
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1uqhjs | how do first responders or hospital personnel know who to contact if you have had an accident and are unconscious? | For example, say you've been in a car accident and are rushed to the hospital. What methods are used to find your emergency contact? Obviously your driver's license would be a start, but what about having an ICE number programmed into your phone? Does anyone ever look for that? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1uqhjs/eli5_how_do_first_responders_or_hospital/ | {
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"I believe this generally sorted out only after you get to the hospital.",
"Well, in my case when I was involved in a battery and knocked unconscious; someone found my phone and got my dad's number out of my contacts and called him. \n*Edited*",
"I worked in an ER and to find contact info for patients who were unable to provide it, we would look in wallets and cell phones for listed emergency contacts (ICE is recognized by hospital staff). If none were listed, we would look through \"recent calls\" to get in touch with someone who might know who we should call, or through the contact list for \"mom,\" \"dad,\" etc. \n\nIt's worth mentioning that if you have a passcode on your cell phone, hospital staff can't find contact numbers in an emergency. I suggest putting a small piece of paper with emergency contact info in your wallet or purse, and including your passcode on that too. ",
"Cop here. \n\nI can't speak for all Police and Fire, but the first thing I do is check the driver's license. If they don't have an ID, I'll run the license plate on my computer and see who it comes back to (assuming it's a car accident). From there I'll find a name and start looking for contact information. \n\nIf it's not a car accident, and there is no identification on their person. Start checking cellular phones. Last numbers called and start calling and asking questions. Sometimes tattoos give a last name, or at least an identifying mark. Worst case scenario, you can't identify them and you wait for them to wake up, or if they're dead, fingerprints/DNA sometimes can help.\n\nOdds are someone is going to notice they're missing and/or had lack of contact for a while and will come forward looking for the person. It's very rare to be able to be completely anonymous these days. Another resort is putting the picture of the person on the local news for someone to identify them.\n\nAs a suggestion. A good practice is to leave your cell phone unlocked, and program all your contacts in with their first AND last name. That way if something catastrophic does happen, responders can go through the phone and see a lot of family members and know where to start with contacts. For example, if my last name is Smith. There will be a lot of Smiths in my phone. If your mother's name is Linda Smith. Program it as Linda Smith (Mom). Or just Mom.\n\nHope this helped."
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49vlan | what ever happened to the sequestration? | So I remember sequestration happening but there was never really the fallout everyone was talking about. So I googled and looked for some news articles and just never found one that sufficiently answered my question. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/49vlan/eli5_what_ever_happened_to_the_sequestration/ | {
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"The simple answer is it happened and almost nothing has come of it. The people that said the sky would fall were wrong, and the people who said it would fix our deficit were wrong. That's it.\n\nSequestration is the exact prime example of why you cannot just listen to the news and \"experts\" to determine what is going on. People lie and exaggerate to get more attention. ",
"Oh there was fallout... it just affected a small portion of the population. Basically what happened was this: a wide swath of federal employees were deemed \"essential\" by various cabinets. So *a lot* federal employees continued working, but were unpaid. This is why you didn't notice a huge shut down of services. There were a few exceptions, but not many. At the end of sequestration both parties agreed to go back and pay federal employees who weren't deemed \"essential\" even though they hadn't worked. Federal employees who did work through sequestration were eventually paid as well.\n\nI worked for the federal government at that time and they gave us letters to give to our landlords, credit card companies, etc explaining why we were being paid. Everyone at the time worked with me and I wasn't charged a late fee for anything. So basically I diverted all my funds to necessities like food and gas. When I got my sequestration check I paid all my bills. Everything worked out fine. I am still a little sour about federal employees who *didn't* work getting paid... that wasn't really fair to those of us who worked through it. Basically they ended up with a paid vacation and we didn't get jack shit for showing up like good little government drones."
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zaf6x | What effect does machine generated wind (i.e. a fan) have on sound waves? | When my fan is facing into my apartment and wind is being blown in to keep it cool, does it have an effect on the sound waves coming from my speakers? With the fan turned off, would more of the sound waves reach the outside (and further annoy my neighbors)? | askscience | http://www.reddit.com/r/askscience/comments/zaf6x/what_effect_does_machine_generated_wind_ie_a_fan/ | {
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"Sound travels at a speed relative to the medium it's in (the air). For example, in the cockpit of a fighter jet, no matter how fast you're going, sound will always travel away from you when you speak at about 340m/s (depending on air temperature/pressure etc) because the air is moving with the jet, but the sound that the jet creates from its engines and emits out into the atmosphere can only travel at about 340m/s relative to the stationary air the jet is flying through, and so the plane zooms passed the sound as soon as its emitted. So all the sound piles up and makes a shock wave and a sonic boom, but that's a different story.\n\nSo when you have sound travelling through air that's being blown by your fan, it will be travelling a little bit faster/slower relative to the room (depending on which direction the fan was pointing) than if the fan was turned off.\n\nHowever, the speed of sound is huge compared to the speed of the air blown by your fan, so the difference is pretty much negligible.",
"The human hearing system detects individual sounds based on energy in focused frequency bands. Sources of broad band noise (like a fan) mask other sound sources by masking and blurring the frequency bands of other sounds. Despite the overall amplitude being higher, the sound of the music is less likely to be registered, and thus less likely to be a nuisance, when masked by broad band noise. So yes, a fan (or running water, or other white noise source) will usually make your noise less irritating to your neighbors."
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64dj5x | why does 101 mean the basics of something rather than just 1 or 001? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/64dj5x/eli5_why_does_101_mean_the_basics_of_something/ | {
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"It's based on a standard for how college classes are numbered. All the first-level classes are 1XX, second level are 2XX, etc. \nBased on that model, the basic beginner class on any subject would be *Subject 101*",
"In a college curriculum, courses are numbered to indicate both the level (100-level courses are more basic than 200-level courses) and, frequently but not always, the sequence of courses (you have to take Biology 101 before you can take Biology 102). \n\nA course with a number of 101 is typically the first introductory-level course offered in a discipline. \n\nWhy isn't it 100, though? Well, first, it's the sequency. If you have to take 101 before 102, it's easier to understand and remember that 10***1*** is *1st* and 10***2*** is **2nd** that it would be to remember that 100 is 1st and 101 is 2nd. \n\nAlso, at some institutions, the number 100 is reserved for remedial courses. So as a typical first-year student at a US university, you would be likely to take English 101 in the fall and English 102 in the spring ... but that assumes that you have the basic skills in reading and writing from high school. If testing shows that you aren't quite ready for the college-level English courses, you might have to take an English 100 class to brush up those skills before moving on to 101 and 102. That's only at some institutions, though, and not as consistent as the 101, 102 style numbering. ",
"In college, within a department, first year courses start with a 1, second year with a 2, third year with a 3, etc.\n\nThe *first* first year course you take often *ends* with a 1. A new freshman in their first semester might be taking Psychology 101, Chemistry 101, and Economics 101. The second semester general courses would be 102, and a second year course would be 201. As courses get more specific and electives become involved, the courses are no longer sequential. Child Psychology might be 335, while Abnormal Psychology might be 470.\n\nNote that this system is not universal, and most colleges today use 4 digit class codes.\n\n",
"It's the same reason hotel rooms often start at 101, because it's helpful to attach 1 to the number to indicate first (floor/year) so as to not later mess it up later. If the rooms on the Hotel's first floor were 1, 2, 3, the second floor would be 101, 102, 103 (or even worse, 45, 46, 47 if we just straight up count). Similarly by attaching 1 to the beginning to indicate first year courses as \"101\" we can indicate that they're first year courses and \"201\" or \"250\" are second year courses and \"301\" and \"375\" are advanced/third year courses.\n\n100 is usually reserved as a pre-101 course that is somewhat remedial in nature (e.g, for a person who is capable but for whatever reason isn't familiar, like a returning student who hasn't taken math in 20 years), with numbers from 95-100 being *really* remedial (I had a friend who had to take Math 97 their first semester of college, which was like high school freshman-level algebra)"
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5d217t | I've read that in the 1800's, US military officers were drawn from the upper class. If so, was it possible that a lower class citizen could perform well in school, go to college and be commissioned regardless of his prior social status? | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/5d217t/ive_read_that_in_the_1800s_us_military_officers/ | {
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"Yes, it was possible. The prototypical example would be Andrew Jackson, the son of recent Irish immigrants (his older siblings were actually born in Ireland - that's how recent his parents had immigrated before his birth). Jackson rose to the rank of Major General in the Army and, of course, eventually reached the highest office in the land in 1828 (inaugurated 1829). ",
"It was certainly possible... Take a look at the lists of graduates of the United States Military Academy at West Point. Though many of the cadets were of course from the upper classes, they included among their ranks many from less well-to-do backgrounds, including that of Henry Ossian Flipper, who was the first black to graduate from the Academy and be commissioned-- he was born a slave.\n"
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3106yu | Did the discovery of the Higgs particle actually prove or disprove either Super-symmetry or the Multiverse theories? | Watching Particle Fever, there was all this excitement that the Higgs would decide between one or the other; and conveyed a very different picture of the universe between the two; but seemed to indicate the results were inconclusive? | askscience | http://www.reddit.com/r/askscience/comments/3106yu/did_the_discovery_of_the_higgs_particle_actually/ | {
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"Nope. It confirmed a prediction of the [Standard Model of Particle Physics](_URL_0_).\n\nThe Standard Model doesn't say anything about supersymmetry (often abbreviated to SuSy) or the multiverse.\n\nSuSy is a hypothetical extension to the Standard Model. It's a pretty extension, but to date there is absolutely no experimental evidence for it. In fact, the Large Hadron Collider has substantially constrained the properties of SuSy - but has not disproved it.\n\nThe multiverse is a prediction of string theory, which is currently so far beyond the realm of detection by any imaginable experiment as to place it almost outside the bounds of science."
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2iszqc | why are arabs and people from north africa (egypt, libya, morocco, tunisia, etc.) labeled as "white" or "caucasian" in the us census? | I did some research before posting but I couldn't find a legitimate answer so I come to Reddit in hopes that someone can shed some light on the matter.
I am Egyptian and on my papers it says I am white. Whenever I fill out anything is official I label myself as white. I even had an instance when I was younger where I labeled myself as "other" and wrote "middle eastern" for a survey and the surveyor handed back the form and asked that I put down white.
I have nothing against being white. The only reason I ask is because... well... I am not really white. I am fair skinned but still. When I go to my white friends whose parents or grandparents or great grandparents are from Ireland, or Germany, or Italy, or any other white country and tell them that I am white they always give me a funny look.
So why are Arabs labeled as "white" or "caucasian" even though socially we are not viewed that way at all? Why aren't we a separate race or group? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2iszqc/eli5_why_are_arabs_and_people_from_north_africa/ | {
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"Race is a construct. There was a time when Russians, Irish and Italians weren't considered white themselves. ",
"Though race is a social construct, and colloquial speech generally equates \"Caucasian\" with \"white\", Caucasian includes people from Europe, North Africa, the Middle East, and the Indian sub-continent. Since race doesn't really mean anything genetically, it really doesn't matter if you're \"Caucasian\" versus \"sub-Saharan African\". As for why you're not viewed as \"white\" even if you are \"Caucasian\", that goes into the historical and social matter of whiteness, institutionalized racism, immigration, and much more. For a while, \"white people\" were only a very small portion of Europeans, excluding many people we'd now considered white like the Irish, Italians and Russians, (and possibly Ashkenazi Jews), but they were over time, subsumed into the \"white\" race. But racists in the US and Europe still didn't consider people from the Mideast and North Africa to be white. This racism still informs our culture, even if we are not ourselves racists, and that's why you, as an Arab Egyptian, are not socially viewed as \"white.\" \n"
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2ilran | why do older tvs have a weird screen effect while being viewed on another camera? | The kind of effect you can see when you're family is recording you as a child while you're smacking the TV in the 90's. | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2ilran/eli5_why_do_older_tvs_have_a_weird_screen_effect/ | {
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"because the refresh rate of the TV screen collides with the frame rate of the video resulting in an \"animation\" of said refresh rate - the line moving up or down the screen. It's similar to the way rims on a car often look like they are going on the wrong direction on film, or how in a strobe environment water droplets look like they are travelling up instead of down."
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9e4h4l | why do some offices have a pc connected to a virtual machine? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/9e4h4l/eli5why_do_some_offices_have_a_pc_connected_to_a/ | {
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"In my organization, we dealt with a large amount of sensitive data. SSNs, DOBs, Names, Addresses etc. We are laptop heavy and our rules stated that we were never allowed to work with that type of data on our local machine, and must be signed into a remote server.\n\nThe idea behind that is to ensure that no sensitive material is stored on the actual machine in case of theft or breach. The remote server machine is much more secure.\n\nAdditionally, it's two step credentialing. One log in for the local machine, a separate username and pw for the remote machine.",
"For my firm, working from a virtual server means that updates are significantly easier. Having to update a program individually on 600+ computers would be an IT nightmare (for obvious security reasons, workers do not have the rights to install programs themselves). Working on a virtual machine allows IT to update much more quickly and smoothly.",
"We have a certain number of licenses for very expensive software that only exist on virtual machines. We are a global company so folks on one side of the world are using the very expensive software while the other side of the world sleeps and then vice versa. We don't have to buy a license for everyone in the company to have this software locally, just enough to support the folks working at any given time.",
"When the user connects a VM is spun up using a copy of IT's VM template. IT can control the VM template, to patch it or whatever, without any pesky users. If something goes wrong, or some malware gets in the VM - poof it gets blown away when the user logs out and a new VM is made from the template when they log in again. This ends persistent malware.",
"Because you can use **any** PC to connect to that **same** VM.\n\nYou get the same desktop whether you are in your office, at home or at a remote worksite. If you spill coffee on your laptop, you don't have to worry about the last time you backed up, everything is backed up at once on the VM server. The *real* machines are locked up in a data center and babysat by experts, so you don't have to care so much about the other ones. You can also get away with giving everyone cheaper, less powerful hardware. \n\nThere are security and support advantages as well. Laptop get stolen? Stupid employees put malware on their machines? Need to install a crucial security patch **right now**? The VM acts as a firewall, giving the company complete control of the important parts will leaving the employees with a lot of flexibility."
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48jkk7 | how can a state be projected to be won by a candidate with only 1% of the polling reporting in? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/48jkk7/eli5how_can_a_state_be_projected_to_be_won_by_a/ | {
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3ggbvt | why is democracy the go to political system despite its inherent instability with every election. what made it a better choice than something else? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/3ggbvt/eli5_why_is_democracy_the_go_to_political_system/ | {
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"I'm probably paraphrasing here, but I always dug The old saying that \"Democracy is the worst form of government, followed by everything else.\"",
"It is better to have a bit of instability every few years and the ability to peacefully replace the current douche with a turd than to be stuck with a nutjob that cannot be changed at all. ",
"The instability of every election is the strength of a democratic process. It means that, at least in theory, one person or group of people can't entrench themselves and turn the government into their own machine and the country into their own kingdom.\n\nThe people gets a mandatory opportunity to replace those in power every few years, again in theory meaning that if we are dissatisfied with them, we can replace them.\n\nOf course over time people who crave that kind of enduring power have created all sorts of different ways to remain in power despite the rules, either by coup or by election fraud or simply by having a dual party system where both parties talk very differently, but act very similarly, and we get to pick a different figurehead every few years.",
"Actually, it is not. We are a Republic. Most 'democracies' are actually republics. The difference is that we elect people to represent us and make decisions for us. This is flawed in that the person elected gets to pick and choose which things he/she does to represent the electorate and which things he/she does to represent anyone or anything that helps get reelection.\n\nBut.....the reason why this is a good thing is this: In a pure democracy, it is strict rule of the 51%. The 49% get absolutely no say in governing. Meanwhile, other forms of government tend to encourage totalitarianism and rule of an elite few at the expense of the many. A Republic lets the masses get representation in the government without having to make the lame day-to-day decisions of government and also has some safeguards in place to protect minorities from the rule of the majority.",
"My political professor put it in the best way: \"Democracy is inefficient and slower in putting into action compared to other governments but its the government system with the best track record in terms of longevity and stability.\" \n\nMost monarchs today turned into democracy. My opinion, is that democracy is the only form of government which citizens have a say in their government. \n\nEverything above is assuming it is actual democracy and not democracy in name. ",
"1. Stability isn't the only important consideration. It's a pretty commonly-held idea that governance is only moral with the consent of the governed, and this makes democracy the most legitimate form of government.\n\n1. Autocrats are thoroughly capable of being crazy, incompetent, paranoid and/or unstable. In a mature democracy with strong institutions and checks and balances, demonstrating these traits is likely to make you unelectable.",
"submitting to ANY form of government requires a citizen to give up a particular degree of individual freedom in exchange for the perks that one can better obtain from a government..these perks includes social safety and security, healthcare, industry and technology, and the sense of belonging to something greater than yourself..\n\nthe best thing about democracy is it allows the people to enjoy the remaining freedoms that they have without really making them feel like they are completely rules..\nthey are still ruled by certain men/group of men, but they have the tools in their hands to dictate who those men/group of men ruling them are..\n\nthe problem with any other form of government is that\nFirst: it is predictable who gets to rule the people and the people doesnt really have a say on who that person/group of people to rule them are\nSecondly: individual freedoms are much more restricted in order for the ruling individual/party to secure their continued foothold into power\n\n(while that may sound completely bullcrap from a western democratic citizen's purview, consider viewing it from the perspective of a citizen of a third world \"democratic\" country..consider the Philippines for example..since nationhood during WW2, they have adopted democracy as their form of government..however, it is an illusion since the highest and middle levels of government is monopolized by elite families, passing on political office from parent to offspring..a lot of people have become demoralized by it over time that there have been several mutinies in the past to overthrow the system, and when it was clear nothing is going to change no matter how much blood is spilled, those who can, started fleeing the country instead, touching off an event called \"the brain drain\", where the first to flee are the educated professionals, leaving a massive shortage of skilled labour in the country..)",
"I disagree with the premise. Maybe I have a different definition of instability, but at least in my experience in the US, even when the outcome of the election for our highest office, President, took a significantly longer time to resolve and was surrounded by controversy, there was no governmental instability. The country still functioned the way it was supposed to. There was no confusion about who was in power. No violence. No calamity. Government services were still performed as usual. What part of that, or any other election in the US has been unstable?\n\n"
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nen8m | How many calories does the human brain consume in a day? | askscience | http://www.reddit.com/r/askscience/comments/nen8m/how_many_calories_does_the_human_brain_consume_in/ | {
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"Your brain requires a tenth of a calorie a minute. That's 6 calories an hour. A person thinking harder will burn up to 50% more calories. Although this is not a lot, you have to think about the relative mass of the brain compared to the rest of the body. \n\n_URL_0_\n_URL_1_",
"If you consume 2000 calories a day, then about 400 of that goes to the brain. I have no idea if that scales or not though. _URL_0_",
"Your brain runs around ~~10 Watts~~. 10 Watts = 10 Joules per sec. There are 4.184 Joules in a calorie (little c, not Calorie, which is 1000 calories). That's 2.39 calories per second. There are 86400 seconds in a day. 86400 x 2.39 = 206496 calories, or ~~**206.5 Calories per day.**~~\n\nEDIT: I was going off of some research that I had done about a week ago, namely [#30 in this list](_URL_0_). Being lazy as I am, I didn't read into it and just remembered the 10 watts. As several people in the comments are saying, the power is closer to 20 watts. [WolframAlpha](_URL_1_) is one source of this other wattage. So double my original estimate = 413 Calories.\n**tl;dr: 413 Cal, not 206.5**",
"When we're discussing biochemistry, it's important to distinguish between calories and Calories.\n\n1 Calorie = 1000 calories\n\nHopefully that will avoid some confusion. :)",
"Part of the original question wasn't answered, and something I've always wondered. In general does thinking more/harder change the amount of energy your brain uses? I'm sure I would have heard about it before, but is there anything you can do to make your brain burn more? (I know the question is dumb, but I also know there are plenty of five year olds asking their mommies and daddies this same question... or it's just me)",
"Rule of thumb is that the human brain uses 20-25% of your daily calories assuming not over eating etc. This is a big piece of conversation in evolutionary biology as such a high calorie use in a brain is pretty unique to humans due to how expensive it is when you could just be an automaton and bite shit.\n\n_URL_0_",
"Where does the brain get calories if you're starving?",
"In Robert Sapolsky's (the Stanford neurobiologist) TED talk [here](_URL_0_), he says this:\n\n > You have two humans, and they are taking part in some human ritual. They are sitting there silently at a table. They make no eye contact; they’re still, except every now and then one of them does nothing more taxing than lifting an arm and pushing a little piece of wood. And if it’s the right wood and **the right chess grand masters in the middle of a tournament, they are going through 6,000 to 7,000 calories a day thinking**, turning on a massive physiological stress response simply with thought and doing the same thing with their bodies as if they were some baboon who has just ripped open the stomach of their worst rival, and it’s all with thought, and memories and emotions. And suddenly we’re in the realm of taking just plain old nuts and bolts physiology and using it in ways that are unrecognizable.\n\nCan someone explain or verify this for me? Seriously mindblowing, if true.",
"This high rate of metabolism is remarkably constant despite widely varying mental and motoric activity [(2).](_URL_0_)",
"Your brain uses about 20% of your body's energy, so if you eat 2,000 calories a day, about 400 are going to your brain.\n\n_URL_0_",
"Your brain requires a tenth of a calorie a minute. That's 6 calories an hour. A person thinking harder will burn up to 50% more calories. Although this is not a lot, you have to think about the relative mass of the brain compared to the rest of the body. \n\n_URL_0_\n_URL_1_",
"If you consume 2000 calories a day, then about 400 of that goes to the brain. I have no idea if that scales or not though. _URL_0_",
"Your brain runs around ~~10 Watts~~. 10 Watts = 10 Joules per sec. There are 4.184 Joules in a calorie (little c, not Calorie, which is 1000 calories). That's 2.39 calories per second. There are 86400 seconds in a day. 86400 x 2.39 = 206496 calories, or ~~**206.5 Calories per day.**~~\n\nEDIT: I was going off of some research that I had done about a week ago, namely [#30 in this list](_URL_0_). Being lazy as I am, I didn't read into it and just remembered the 10 watts. As several people in the comments are saying, the power is closer to 20 watts. [WolframAlpha](_URL_1_) is one source of this other wattage. So double my original estimate = 413 Calories.\n**tl;dr: 413 Cal, not 206.5**",
"When we're discussing biochemistry, it's important to distinguish between calories and Calories.\n\n1 Calorie = 1000 calories\n\nHopefully that will avoid some confusion. :)",
"Part of the original question wasn't answered, and something I've always wondered. In general does thinking more/harder change the amount of energy your brain uses? I'm sure I would have heard about it before, but is there anything you can do to make your brain burn more? (I know the question is dumb, but I also know there are plenty of five year olds asking their mommies and daddies this same question... or it's just me)",
"Rule of thumb is that the human brain uses 20-25% of your daily calories assuming not over eating etc. This is a big piece of conversation in evolutionary biology as such a high calorie use in a brain is pretty unique to humans due to how expensive it is when you could just be an automaton and bite shit.\n\n_URL_0_",
"Where does the brain get calories if you're starving?",
"In Robert Sapolsky's (the Stanford neurobiologist) TED talk [here](_URL_0_), he says this:\n\n > You have two humans, and they are taking part in some human ritual. They are sitting there silently at a table. They make no eye contact; they’re still, except every now and then one of them does nothing more taxing than lifting an arm and pushing a little piece of wood. And if it’s the right wood and **the right chess grand masters in the middle of a tournament, they are going through 6,000 to 7,000 calories a day thinking**, turning on a massive physiological stress response simply with thought and doing the same thing with their bodies as if they were some baboon who has just ripped open the stomach of their worst rival, and it’s all with thought, and memories and emotions. And suddenly we’re in the realm of taking just plain old nuts and bolts physiology and using it in ways that are unrecognizable.\n\nCan someone explain or verify this for me? Seriously mindblowing, if true.",
"This high rate of metabolism is remarkably constant despite widely varying mental and motoric activity [(2).](_URL_0_)",
"Your brain uses about 20% of your body's energy, so if you eat 2,000 calories a day, about 400 are going to your brain.\n\n_URL_0_"
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"http://www.livestrong.com/article/304577-calories-burned-by-brain-activity/"
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5cobkg | Can a computer simulation create itself inside itself? | You know, that whole "this is all computer simulation" idea? I was wondering, are there already self replicating simulations? Specifically ones that would run themselves inside... themselves? And if not, would it be theoretically possible? I tried to look it up and I'm only getting conspiracy stuff. | askscience | https://www.reddit.com/r/askscience/comments/5cobkg/can_a_computer_simulation_create_itself_inside/ | {
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"A cellular automaton can simulate the rules of its own world with some slowdown. [Here's an example with Conway's Game of Life](_URL_0_). (If you aren't familiar with Conway's Game of Life, you can read [this](_URL_1_) for an intro.)\n\nA program written in a Turing-complete programming language like C is capable of interpreting itself. If you wrote a C program that implemented a C interpreter that interpreted its own source code, it would run forever with an ever-growing number of recursive levels.",
"It depends on what exactly you mean. You can't directly have each bit of a computer mapped out by bits in the computer with a computer of finite size, but you could have it compress the data. For example, there's something called a [Quine](_URL_0_) that's a computer program that prints its own source code. Actually doing computations with it using limited space would be much more difficult, but not impossible.",
"A computer can emulate another computer (check [this](_URL_0_) out!). A computer can, in fact, emulate a simplified version of itself. The only problem is, as the usage of the emulated computer (or CPU) approaches the maximum speed/usage of the *real* computer, the number of states that can be simulated approaches one. \n\nEventually, with the emulated computer under 100% load, the emulation will halt - unable to continue because it will require more memory and power than the *real* computer is able to provide it. /u/Begging4Bacon explained it very well:\n\n > The computer would have to be able to simulate itself in a random state. The random state would take up all the memory, leaving none for the hardware itself.",
" > Specifically ones that would run themselves inside... themselves?\n\nHave you seen programs like VMWare and other virtual machines, that let us run a normal PC, and then have many \"virtual\" machine inside that?\n\nServer hosting companies have used it for a few years now, and once logged into one its very hard to tell you're actually running on a machine inside a machine. And although it gets slower and slower to do so, you can evening run a virtual machine inside a virtual machine, inside a virtual machine, and so on.\n\nIf we're in such a simulation I'd like to think the designers are well ahead of us, where we're doing it already for web servers and similar.",
"What you're talking about is the Simulation Hypothesis (_URL_0_), the idea of which is that if technology continues to progress the logical conclusion is that it's impossible for reality to *not* be a simulation.\n\nIt makes a few assumptions. A) Some sentient life out there is \"post human\" technology and capable of simulating the universe and B) that sentient life has ever had the desire to run ancestry simulations and C) we're the only people exactly like us.\n\nCalled a \"trilemma\", you're basically saying that \"somebody out there can make a simulation of the universe, so they do\". Well, if they can do that, then the simulation eventually can, and that simulation eventually can, and that simulation eventually can, etc etc.\n\nYou end up with this kind of infinite loop where there's definitely a point where the loop began, but there isn't an end point. And because the simulation exactly replicates reality, it's impossible to determine whether we (current humans as we know them) are the start point.\n\nWelcome to the simulation.",
"Any Turing-complete computer can perform any computing operation possible on any other Turing-complete computer. And as far as we know, no other computing operations exist.\n\nSince most computers are Turing-complete, this implies that a computer can in principle perform any simulation (assuming that enough memory and enough time is available). Since we are not aware of any computational operations (phenomena) in the physical world that cannot *in principle* be simulated, this means that the answer to your question is yes. \n\nAccording to our current understanding, physical reality could in principle be simulated on a computer. It would require an unfanthomably powerful computer which might not be possible to build in our universe, but as far as I know, we are not aware of any theory that precludes this.\n\nThe question of whether any organism in such a simulated universe would be conscious is currently in the realm of philosophy; our current scientific understanding cannot answer this question.",
"No. \n \nIf a computer has limited resources i.e. limited memory, it would not be able to store a *fully* functional simulation (with the same amount of resources) of itself in it's memory. \n \nThe simulation could compress some of the parent computer's data to fit into the reduced memory resource but it would lose some functionality because some data (high entropy data ie random noise) cannot be compressed. Therefore the simulation would not be possible if the original computer's memory was full of noise.",
"To answer this question meaningfully, we have to specify what a _computer_ first is.\n\n# Cellular automata\n---\nThe 2D block cellular automaton with two states, in which a cell becomes \"live\" only when its four predecessors have exactly two adjacent live cells, _can simulate itself_ with a factor of two slowdown and a factor of two size blowup, but is not known to be Turing complete. See The B36/S125 “2x2” Life-Like Cellular Automaton by Nathaniel Johnston.\n\n# Modern programming languages\n---\nIt is very common to write an X-in-X compiler. The process is called [bootstrapping](_URL_0_).\n\nThis is not a simulation, however. Interpreting an X-in-X compiler as it is fed into itself would need infinite input in order to not halt (technically, stuck waiting for input).\n\n# Turing machines\n---\nA Turing machine that can simulate an arbitrary Turing machine on arbitrary input is called a _universal Turing machine_. The question how \"simple\" does a TM have to be to still be a UTM is an open problem in CS.\n\nReal computers like the one I'm typing this on and the ones you're reading this on are not Turing machines - they are decidedly finite in nature. We call them _linear bounded automata_. Turing machines formalise and model (all) aspects of those.\n\nNow let's answer the question.\n\nNo, a computer cannot perfectly simulate itself in addition to something else without violating basic information theory: there exist strings which are not compressible.\n\nHere's the simplest possible proof: suppose the computer has a total of _N_ possible states, and suppose there is something outside of the computer in the universe, so the universe has at least _N+1_ possible distinct states. With zero overhead, each state of the computer can correspond to a state of the universe, but since the universe has more states than the computer, by the pigeonhole principle, some states of the universe will map to the same state of the computer, in which case the simulation will not be able to distinguish between them. QED.\n\nNext hypothesis: a computer cannot perfectly simulate itself.\n\n(not very formal) Proof: Assume the computer can simulate itself. This means the computer is running a program P which is simulating the computer running P, which is simulating the computer running P, and so on _ad infinitum_. We have reached an infinite regression, which means the computer cannot be simulating itself. QED.\n\n---\n_Addendum_ We can actually prove a computer cannot simulate itself pretty easily, like so:\n\nLet C be a linear bounded automaton, and let C take another LBA M as its input and decides whether it halts or not. It does so by simulating M, then do the opposite: C halts if M does not, and loops forever if M halts. Then C(C) demonstrates a contradiction:\n\n* if C halts, C(C) loops forever, which cannot be true\n* if C does not halt, C(C) halts, which is false\n\nQED.\n\n\nPS. I'm not saying a computer is exclusively one of these 3 things. Attribute lack of other notions of a computer to my ignorance and boredom. :-)",
"In terms of computer science, anything that's Turing Complete can simulate anything that is Turing Complete. Since modern computers are effectively Turing Complete, it means any computer can do anything any other computer can, ignoring time and memory constraints. So if we can write an algorithm/program that simulates a computer down to the atomic level completely accurately, it can in theory simulate its own physics. \n\nOf course, Turing Machines have infinite memory and currently our computers have finite memory. With a computer that has a finite amount of memory from when it starts running the program, and depending on what level of detail you use, it's possible for adding X amount of memory to the computer requiring some Y amount of additional memory used where Y > X, which would make it impossible to ever have enough memory to store all the relevant data about the system.\n\nGiven a computer that could extend its memory bank on demand, such a system could fully simulate itself, because the primary version could have more memory than the simulated version, and by the time the simulated version expands its memory and takes more memory to represent, the primary version could have expanded further. ",
"This may not be what you're talking about, but you may be interested to know that in the event that we were able to simulate a universe, the odds that we ourselves are in a simulation go up to being almost fact, because the odds that we are the \"base\" universe are less likely than being one of many simulations.",
"When I read what you wrote you kind of reminded me about season 3 episode 2 of the Black Mirror series. It's a pretty good and scary episode of what could happen when running a computer simulation in your mind. Obviously it's science fiction at the moment but still worth a watch. It's on Netflix. ",
"Although there are several solid answers already, I'd like to take a crack at this since coming up with a simple explanation is a good way to check me own understanding.\n\nConsider your mind; it's a computer. It can simulate other minds by imagining what they would do in a given situation. You can easily imagine what someone slower than you would do in a given situation, and given enough time you likely could imagine what someone more intelligent would do. In fact, writers do this all the time. But what if you were to simulate yourself?\n\nNow, for the sake of argument, you could exactly simulate yourself by simply being yourself. But let's say you want to go through the trouble of imagining an exact clone of yourself, with your exact same memories, thoughts, and mental abilities.\n\nLet's try it. Imagine yourself. Think about what you're doing right now, and imagine what you would do next, then do it. Now imagine what you would do next, now do it. It's definitely more difficult to imagine how you would react before doing things rather than simply reacting. You could probably keep this up for a while, at least until you encountered a situation where you needed to use all of your brainpower. You could handle such a situation of course, but you would take noticeably longer than normal to do so.\n\nNow there's another problem with exact simulations. That is, that they cannot fully store themselves. For this discussion, let's now imagine a box representing a computer. The volume of the box represents how much data it can store. Let's fill the box with water until it's about a third of the way full. The water represents data filling up the computer's storage. Now, imagine an identical box, equally full of water sitting next to it. The second box, being exactly the same dimensions as the first box, cannot fit into it. A given volume of storage cannot hold more than itself.\n\nBut let's imagine we work around this by squishing the second box until it fits in the first box. By decreasing the volume of the second box to only encompass the used portion of the box, we can get it to fit within the first. This is fine, unless the water in the first and second box exceeds the capacity of the first box, in which case the second box will not within the first unless we start removing water from at least one of the boxes.\n\nOverall, what we see from these thought experiments is that a given computer's ability to simulate another computer is limited. First: It is possible for the simulator to simulate a slower computer that runs as quickly as the original, but it must simulate computers that are equal in speed or faster than itself at a speed slower than the original. Second: A computer cannot store an exact copy of it's own storage space in itself, but it can store an exact copy of it's own data as long as the data occupies equal to or less than half it's storage space.\n\nThere's also an argument to be made that a computer exactly simulating itself would never run, since it would need to simulate itself simulating itself, simulating itself, and so on endlessly. This means that to figure out the first thing it would do would take an infinitely long period of time as each simulation would need to start by starting a simulation and waiting for that simulation to start its simulation, and so on.",
"What I wonder, is how many layers deep we have gone. I guess the idea of what qualifies as a simulation may be a little bit grey. Like if we have 5 layers of computer simulations, maybe it's all still just 1 simulation on the computer and it's only our interpretation that these layers represent simulations. Like, it's hard to say any of it is a simulation at all because there are still basic laws that govern the entire thing without being broken.",
"None of that stuff makes any sense, at all, to apply to our shared reality. Occam's Razor. Just because a person who spent his entire life working on AI and computers and simulations, thinks that all of life might, totally without evidence, be a simulation inside a computer ... might want to give that a second thought.\n\nWhen you spend your life with the chariot as the pinnacle of your technology, suddenly the explanation for the movement of the Sun is, it's pulled through the sky on a chariot. Well of course it is.",
"Just as an aside to some of the excellent answers above, most if not all of the actual parts inside your computer have been simulated on a computer. The CPU, GPU, motherboard et al are designed in hardware-targeting programming languages like VHDL or Verilog, and simulated in software by their designers prior to hardware fabrication. This can include not just the logic itself but a simulation of the material properties of the circuit. In a piecemeal kind of way, what you're suggesting is going on all the time as the next generation of computers are being designed.",
"Thats exactly the theory. We play video games. The games get more advanced. We create games like the sims. \n\nSoon the game characters will have ai so advanced they believe theyre real.\n\nThe theory is that if a simulation so real is created within our existence what are the odds that we are the first to create a simulation. What are the odds that we are a simulation.\n\n Odds favor we are not real creating the first simulation but that we are a simulation which creates simulations.",
"[Gödel's Incompleteness Theorem](_URL_0_) almost certainly applies here. Computer programs are \"formal systems\" in the mathematical sense. Which basically demands that the simulation must be simpler than the original so it can't completely simulate itself to 100% degree.\n\nThis probably is a form of restatement of the 2nd law of thermodynamics as well.\n\nMost common applications of Gödel are not correct but this case probably is.",
"If a computer simulation can emulate itself, then it can emulate itself, emulating itself, and so on, up to a any arbitrary number of nested simulations. Somehow it has to contain knowledge how many nested simulations are currently running. We have no way to represent a number that can be any value and be unbounded. If you use an atom to store 1 bit of information (or any finite number of bits per atom, or per some particle) you will eventually run out of atoms. There is a limit to how big of a number you can represent.\n\nTherefore, a computer simulation cannot keep track of how many nested simulations of itself are running, so it cannot completely represent itself.",
"Ever heard of a [virtual machine?](_URL_0_)\n\nIt's not self-replicating by default, but you might be able to tweak one to create a VM that would endlessly create similar VMs inside of another VM running inside the master VM, etc.",
"There are a lot of technically correct responses here. But I can read between the lines - you want a fun answer. I'll keep it as non-technical as possible while still being as accurate as I can be.\n\nIn our real world, we can build hardware to support multiple software layers. After decades of developing these software layers, we have made designing games and simulations extremely accessible. In some games, the player can build computer hardware using the game rules. \n\nA perfect example would be the [redstone computers](_URL_1_) in Minecraft. Those have very basic functions, however. About as advanced as an old adding machine, though it looks like some can run stuff like Tetris (though it's ROM-only, no new games can be \"installed\" because the hardware itself must be altered to change I/O.) Nowhere near as complex as the IRL computer running the game itself. Still, it's a first step. [Moore's Law](_URL_0_) says it's not a pipe dream, but it's just a matter of time. \n\nHopefully that was a bit more \"fun\" than the correct answers about virtual machines and emulators.",
"Create a virtual box machine of Ubuntu, download an Ubuntu iso to the virtual box machine, install virtual box to the virtual box machine, run Ubuntu in virtual box in the virtual box machine.\nUbuntu in Ubuntu in (Windows/Linux/whatever you use to host the original virtual box).",
"Within the computer game Minecraft, it is possible to build computers that are programmable using combinations of Red Stone equipment. Say that a fully programmable computer is built within the Minecraft game, and that this computer has been programmed to run a game of Minecraft. So, on your desktop you have the 1st (original) Minecraft running, and within the 1st Minecraft there is a 2nd game of Minecraft running on that Red Stone computer. \"Level\" is used to describe the depth of the game, so that the 2nd game would be said to be the 2nd level simulation.\n\nSay we replicated this action of building Red Stone computers within each game so that the example goes from 2 levels to 3 levels deep, or 6, 10, up to infinity. \n\nIs this possible? What sort of speeds are we looking at? What kind of power is needed to run a game that has 3 levels to it? ",
"This makes me think of the rick and Morey episode where he has a miniverse society running his spaceship engine. They go inside it to find out that that society created a miniverse to run their society, and that society was on the verge of creating one too!",
"This is like asking if you can fit a copy of a room inside that room itself. Well, that room has walls, a roof, a floor, and other things - for a computer, there are always a number of resources available. \n\nFor simplicity's sake, let's say there's memory (storage space, or GB) and computing power (calculating speed, or MFLOPS - million floating operations per second). Disregard that I put G and M on those units, it doesn't really matter for the example.\n\nLet's say A is trying to simulate a copy of itself, A'. A has 10 GB of space and can do 10 MFLOPS. However, A needs to store its own code, and it needs to store some things in memory as well. Let's say that takes up 1 GB. But A' needs to have 10 GB of space available, so now we can't simulate A'.\n\nSimilarly, A can do 10 MFLOPS, but the program to run A' takes up some FLOPS just to run the simulation, say 1 MFLOPS. Well, now we only have 9 MFLOPS left for the A' simulation, so we can only run A' at 90% speed, so the simulation doesn't work - we could run it slower, but we can't get around the space requirement, and running slower than the world around it would potentially make A' not function properly.",
"If the universe itself is a simulation then whatever is simulating our universe may not be bound by the laws of physics as we know them and could in theory implement infinitely recursive emulations.\n\nIf it's like the computers we know and love though, it's not possible to run a perfect simulation of the simulator itself. The space of all possible states inside the simulation would have to be accounted for alongside the code to implement the simulator, meaning that by definition such a simulator would need to have enough memory to store itself PLUS more."
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1a9nab | Why does a curling rock turn the same direction the rock is spinning? Why does sweeping reduce the curl? | [This wikipedia article](_URL_0_) suggest that friction increases at sliding speed of skating increases. If that is the case, the rock should turn the opposite direction, as a glass on a table does. I have had a hard time finding information on the mechanism of things sliding on ice, and there seems to be some disagreement as to why ice is slippery. Perhaps some help with that would be useful? | askscience | http://www.reddit.com/r/askscience/comments/1a9nab/why_does_a_curling_rock_turn_the_same_direction/ | {
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" > Why does a curling rock turn the same direction the rock is spinning?\n\nI could not find any conclusive evidence either. However, I will point out that the section in Wikipedia article mentioned several alternate explanations of increased friction as skating speed increases, including different skating techniques. I will also point out the surface of a curling sheet is not a smooth surface - it is roughened by the introduction of pebbles. This makes it behave very differently than on ice (in fact, you can't throw a stone very far on smooth ice because the stone forms a nice seal on the ice, and that has a suction effect that drastically slows down the stone).\n\nThe explanations I'm familiar with is that the quasi-liquid layer is mainly responsible for reducing friction, and this layer affects the front of the stone more than the back, because the contact pressure of a 42 pound stone will increase the thickness of that layer. This makes any friction at the back dominate over that of the front. For a clockwise curl, the back of the stone is pushing _left_ on the ice, which makes the stone curl right.\n\n > Why does sweeping reduce the curl?\n\nThe answer to this is more certain. The friction from the broom heats up and softens the pebbles on the ice, and this reduces the friction of the ice. This has the effect of extending the distance of the stone, and also reduces the curl as there is less friction on the stone.",
"First, some facts:\n\n* Curling rocks have a circular running surface that makes contact with the ice. \n* The running surface of curling rocks are sanded, but not completely smooth. \n* Curling ice isn't smooth, it's \"pebbled\" by sprinkling water onto it. This creates what you can think of as a mountain range of various-sized bumps on the ice. These bumps are then \"nipped\" by a blade, so they're all at roughly even height. \n* In curling, the rocks are generally not spun very fast; they usually only spin a few complete circles the entire way down the ice. \n\nLet's say the rock is curling to the left, so the right side is spinning \"forward,\" and the left side is spinning \"backward\" as the rock moves down the ice. This means that the right side of the rock's running surface is moving forward faster than the left side is as the rock moves forward (in other words, the relative velocity is faster on the right than it is on the left). \n\nAs the rock moves, it glides over the edges created by the nipped pebbles. The friction of the ice creates a force against the rock, slowing it down. The rock also creates a force of friction on the ice, changing it's state to be smoother and softer (and therefore less friction for the parts of the rock behind it). \n\nThe fast right side of the rock imparts more friction on the ice, changing its state and making it more slippery, as well as having an easier time just gliding right over the edges of the nipped pebbles. The left side is moving forward a lot slower (relatively), which means that the rock affects the ice less, but the rough ice pebbles are able to \"snag\" a bit more on the rock, slowing it. All in all, the left side is slowed more than the right side. Think of it like the fast side kind of swinging around in front of the slow side as it gets snagged by the ice and held back. \n\nSweeping the ice in front of the rock generates friction and makes the pebbles nice and smooth for the rock to glide over. This reduces the overall friction of the ice on the rock. It still curls, it just curls slower because the force of friction is lower on the rock. \n\nAlso, if you were to spin the rock very fast, it would curl very very little, since the relative velocities of the rock would be very similar, and therefore the friction on each side would also be close (until the rock slows down).\n\n**TL;DR:** The side that's spinning \"backwards\" is moving slower down the ice, so the ice has an easier time \"grabbing\" the rock on that side to slow it down as the \"forward\" moving side swings around it by gliding easily over the ice. Sweeping reduces the overall friction of the ice, making the rock snag on it less. \n\nSources: I graduated with a minor in research physics and I've been curling for three years."
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6qp47b | Is damage of radiation linearly dependent of radiation exposure? | Two questions: Is staying out in the sun for 10 hours straight the same in terms of risk of cancer as ten hours spread out over a larger timeframe? A simalir is wether a single, large dose of radiation has the same effect as several smaller ones? | askscience | https://www.reddit.com/r/askscience/comments/6qp47b/is_damage_of_radiation_linearly_dependent_of/ | {
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"No 10 hours today =/= 10 hours a month.\nIt's not the dose of radiation that would cause harm but the build up. \nThere is a limit to how much radiation our bodies can take before damage occurs.\n\nThat said 10 hours today will cause a significant level and can cause cell damage to chances of cancer(I put alot of stress on chances looking at you mom).\n\n10 hours over a month is not going to have the same level of radiation due to the fact your old cells would have been replaced and your body would have gotten rid of the radiation by now.\n\nso lets say 10 hours today is 10 units, 10 hours over a month is 1 unit per hour - 1 unit per day without exposure.\nso if both end today the 10 hours today will have 10 units while the sparce exposure will be 0~1 units.",
"It's a difficult question to answer, but for the purposes of radiation protection, cancer risk is considered proportional to dose and is not time dependent, in accordance with the [Linear No-Threshold model](_URL_0_). Now that is certainly not true with biological damage in general. For instance, the spreading out of the UV dose will prevent you from getting sunburned. Radiation-based cancer treatments are usually spread out over the course of multiple days or weeks to allow for normal (non-tumor) tissue recovery. But for *cancer risk specifically*, yes, with caveats you can look up in the Wikipedia entry.\n\nInterestingly, some folks think that very small doses of radiation may actually REDUCE your cancer risk (hormesis). But there's not enough evidence to support that at this point, so we still use the linear no-threshold to predict excess cancer risk from radiation. And excessively high doses, well, that will kill you, so I guess at that point it's not really linear anymore...",
"No, these exposures are not at all the same. \n\nThe key is that cells have a tremendous capacity to repair DNA in the hours just after exposure. If it has a chance to repair damage after a small exposure before more piles on, the success rate will be higher."
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17qijj | Flat or disc-shaped planet | Would a flat or disc-shaped planet (at least the size of Earth) be able to hold orbit around the sun or is the globe shape needed to maintain "aerodynamics"? | askscience | http://www.reddit.com/r/askscience/comments/17qijj/flat_or_discshaped_planet/ | {
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"The shape of the object doesn't matter. There's no aerodynamics in space because there's no air. However, a naturally formed planet can't be any other shape due to the laws of gravity.",
"Shape makes absolutely no difference in space. There's no air to push against anything in space. Have you seen the lunar lander? Would you call that aerodynamic? Either way a planet shaped any way other than a sphere would be unstable and pull itself into a sphere eventually."
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1oi99s | why more recently than ever do webpages refresh and not actually go back when you hit the back button? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1oi99s/eli5why_more_recently_than_ever_do_webpages/ | {
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"It is more and more common mispractice to include a 0 second redirect in a site, which as soon as you load a page, redirects you to a slightly different page they actually want you to see. So far, this isn't a bad thing, it helps site design. The problem is, if you hit the back button on most browsers, it will take you back to the page with the instant redirect instead of back PAST that page to the page you came from. It is bad design, and SHOULD be easy to avoid, but some web designers are idiots.\n\nSource: I'm a web developer.",
"Some common elements can be stored on your computer depending on your cache size. But there are alot with dynamic content that is constantly changing such as posts on an image board or forum that need to be updated every couple of minutes.",
"I also have this issue. I use chrome, and also adblock and adblock plus. I read the other day that it's something to do with adblock that is the problem. If you don't use any of these, then I have no idea\n [Source] (_URL_0_)"
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2y5o1b | why do people tie shoe laces and toss them over power lines? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2y5o1b/eli5_why_do_people_tie_shoe_laces_and_toss_them/ | {
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"Three reasons:\n\n1. Gang members do it to mark their territory ([supposedly](_URL_0_)).\n\n2. Bullies steal someone's sneakers and throw them over power lines to taunt their victim.\n\n3. People take their old sneakers and throw them over power lines because they are inspired by (1.) or just think it's cool, funny, or exciting to do.",
"From my personal experience it is a subtle way of showing that there is a drug dealer in the general vicinity. ",
"As others have said, usually drug dealers. Also done by skateboarders/hikers as a form of 'burying' shoes that are too beat up to keep wearing.",
"My dad said that private school kids used to do it on the last day of school since they wouldn't need them all summer and would then get new ones next school year. ",
"There is a video called \"The Mystery of Flying Kicks\" that looks at possible answers to this very question. _URL_0_",
"i work on the university of oregon campus. the kids here do it just because. idiots.",
"The drug dealer theory has always seemed dumb to me, at least as far as it still being true today. Maybe it was a under the radar the first few times people did it, but now that the rumor is widely known (to even police), wouldn't near those shoes be be the last place an actual drug dealer would want hang out?",
"I always thought it was a symbol for leaving the hood",
"Because its funny, and fuck that guy. The stuff about drugs and gangs is nonsense.\n\nSource: lived in the hood most of my life.",
"This is like asking \"why do people draw dicks and write shitty poetry on bathroom walls?\"",
"Regardless of how it originated, it has become so common now that the meaning behind it could be anything. ",
"It's mostly has r.i.p on them a sign of respect for a Fallin friends",
"According to Big Fish, it's to keep you in the paradise of Spectre.",
"When I lived on an Air Force Base, it was a superstition to throw a pair of combat boots up into a specific tree. If the boots never came down, you would never be stationed at that base again.",
"i think Crab Man said it best...\"spontaneous combustion happens all the time. how do you think shoes get caught up in power lines?\" ",
"We used to do it just because it was something to do with your old shoes. We had a shoe tree going.",
"I find it extremely fascinating that so far no one has mentioned the reason I have heard (time and time again): This is something you do when you lose your virginity.",
"I always assumed this was a really awful prank. ",
"It is supposed to be symbolic of you leaving an area for a better place or life. This is why you typically see this in poorer area's.",
"Tofino BC, hundreds of pairs of shoes on wires beside skate park!\n\n_URL_0_",
"I don't buy into the 'shoes over the lines' being crime related because even in the worst parts of Philly it's just kids throwing their shoes over the lines because it's fun. No one needs to advertise where to buy drugs or who's corner it is, it's always pretty obvious.",
"Not sure if this is accurate but someone told me its to signify leaving the hood",
"I found this last year and I'm still waiting for an answer. \nNSFW\n_URL_0_",
"I once saw a a pair of skates over a power line. It's Canada. It's what we do."
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3hz57m | What is the difference between Enthalpy (H) and Heat (Q)? | askscience | http://www.reddit.com/r/askscience/comments/3hz57m/what_is_the_difference_between_enthalpy_h_and/ | {
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"Enthalpy is a Legendre transform of internal energy. It's a state function, so the change in enthalpy between two states doesn't depend on the path you take between those two steps (in fancy words, it's an *exact differential*).\n\nHeat is not a state function; a system doesn't \"have\" a certain amount of heat in it (whereas a system *does* have a certain amount of enthalpy). Furthermore, the heat added or removed from a system between some initial and final state **does** depend on the path you take between those states (it's an *inexact differential*).\n\nFor a reversible process at constant pressure (like a lot of the things you do in chemistry), the differential enthalpy during some process is the same as the heat transferred into or out of the system during that process.\n\nSo that's why in chemistry you often hear terms like \"latent heat of fusion\" and \"enthalpy of fusion\" being used as if they're interchangeable, because they often *are* in chemistry.\n\nThe first law of thermodynamics says:\n\ndU = ~~d~~Q + ~~d~~W, where the strikethroughs indicate inexact differentials.\n\nAnd the (pressure-volume) work can be written as ~~d~~W = - p dV.\n\nBut maybe you want to think about energy as a function of pressure rather than volume. That way if you can keep the pressure constant (like in a laboratory environment), it'll simplify things.\n\nIf you replace the internal energy U with the enthalpy H = U + pV, you find that dH = dU + p dV + V dp.\n\nNow replacing dU with what we have above, dH = ~~d~~Q - p dV + p dV + V dp.\n\nThe two terms in the middle cancel, and all that remains is dH = ~~d~~Q + V dp. At constant pressure (dp = 0), this says that dH = ~~d~~Q.",
"The simplest way to put it is this: heat (and work) are energy in transit, while enthalpy (and internal energy, and Gibbs energy, etc) are measures of stored energy in the system. You probably know the advantage of enthalpy is it's a state function, so enthalpy changes between two given states are always equal regardless of how the change is effected, unlike the heat or work which may vary depending on the process used."
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2i2qzn | Would the water pressure be the same at 100 metres under the surface, even if the water was located in a water tank on land? | askscience | http://www.reddit.com/r/askscience/comments/2i2qzn/would_the_water_pressure_be_the_same_at_100/ | {
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"Yes.\nThe pressure at any point in the water body depends on three things given negligible air pressure changes. Density of liquid , gravitational constant and height below the surface. Given same g and density , at same depths no matter where kept, the pressure will be same.\n",
"Almost, but not quite, yes. If you built an above-ground tank with 200m of water in it and took the pressure at the bottom, it would be marginally different than going 200m straight down into the ocean. \n\n\nThe first reason for this is air pressure: though a 200m column of air doesn't exert nearly as much force as 200m of water it's still a difference. You've got 200m more air on top of the ocean.\n\n\nThe second is gravity anomaly: if you change the location of any gravity rig you'll get some variations, can't say if it'll be a positive or negative change and by how much unless we know which two points we're talking about (except for the free air anomaly: we're definitely going to a higher elevation so that correction is easy enough).\n\n\nThere are additional complications, but each are enlightening and allow you to learn useful things about what's affecting the point of interest."
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1rzgfd | what's the possibility of puerto rico becoming the 51st state of the us? | edit: these are great answers, thanks guys | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1rzgfd/eli5_whats_the_possibility_of_puerto_rico/ | {
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"This is a complex issue so I failed miserably at ELI5 so I did an ELI15 instead. I hope that you're OK with this.\n\n---\n\nIn order for Puerto Rico to become a state two things would need to happen.\n\n1 - Puerto Ricans would need to reach a consensus. \n\nPresidential elections are periodic events where things remain pretty much the same. Because of this the best strategy for the losing party is to wait 4 years and try again. A change in status, however, is a life changing and potentially irreversible permanent event. And if a Puerto Rican group felt that an illegitimate status definition had been imposed on them a cascade of events that would mirror the [assault on the house of representatives](_URL_0_) and the [Ponce massacre](_URL_1_) could unravel. And no American politician would want to risk that.\n\nAnd you have to keep in mind that in Puerto Rico the main political parties are tied to status definitions. (That's why Puerto Rican politicians make some noise on the subject every once in a while. They're just pandering to their voters.) In the island there is no Democratic or Republican party but a status quo political party (PPD), a statehood political party (PNP), and a minority independence political party (PIP). The status quo party and the statehood party have rougly the same number of supporters so they switch seats in the government once every few years and as a result the status of the island is in a permanent political stalemate.\n\n2 - The US government would need to reach a consensus. \n\nThe political status of Puerto Rico is a very risky political issue for any American politician. However, the US government knows about the island's political stalemate so they don't have to take any meaningful actions. But in the unlikely event that Puerto Ricans reached consensus every relevant politician would have to ask himself the two following questions:\n\na - Would a Puerto Rican state add more votes to my political party or would it benefit the competition? Keep in mind that in Puerto Rico there are no Republicans vs. Democrats although the local politicians do affiliate themselves loosely to some extent with those political parties. Republican politicians would reject a new Democratic state and vice versa.\n\nb - Would my constituents approve of adding Puerto Rico as a new state? Keep in mind that although many Americans consider Puerto Ricans to be marginalized and underrepresented American citizens others consider them to be a culturally incompatible burden for the American taxpayers.\n\nSo, even if Puerto Rico could reach a consensus the issue could remain in a stalemate in the US government forever.\n\nThere's a third option but it is very unlikely so I didn't mention it as a plausible path to statehood. The US could just force a status definition on the island like it has done many times before with many territories. But the political repercussions would be too great in this age of ubiquitous communications so unless a very dramatic series of events occurred this won't happen.\n\ntl;dr: It is very unlikely but it makes good news so you'll continue to hear about it regularly.\n\n// Disclaimer: I am a Puerto Rican",
"It's highly unlikely. Congress would need to approve it, and the Republicans would never support the addition of a state whose electoral votes would almost certainly go to the democrats in every presidential election.\n\nThen there's time money issue. If admitted to the US, Puerto Rico would be the poorest state in the us. Not a lot of US politicians want to take that on.\n\nAlso, just over half of Puerto Ricans approved of statehood in a 2012 vote. If the us approved statehood, you'd have quite a few Puerto Ricans actively working against it.\n\nIt might happen someday, but not anytime soon."
]
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"http://en.wikipedia.org/wiki/Ponce_massacre"
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53q1r4 | would it be possible to replace all of your bones with some sort of metal replica? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/53q1r4/eli5_would_it_be_possible_to_replace_all_of_your/ | {
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"Short answer: no. For a couple reasons.\n\nFirstly, there's all the biological functions bone has in the body - as a store of calcium, a site for red and white blood cell production, a fat storage location, and probably more I'm forgetting.\n\nSecondly, there's the material reasons - bone is an amazing natural composite, a living material. It's constantly breaking itself down and rebuilding in response to your needs, which is what makes replace parts with metal so complex. With bone, it's rare to have to deal with fatigue fractures, from years of constant cyclic loading (your leg joints take multiples of your bodyweight in load each time you take a step), as your body rebuilds the bone constantly. Metal isn't doing that, so it can eventually crack.\n\nThere's also the ways it would be held - our body knows what to do with bone, how to attach soft tissues to it, how not to attack it with the immune system - with metal (or any other material really) these things have to be taken into consideration. "
]
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5y4l89 | who's in charge of coming up with street names and is there any approval by a committee? also, if you were someone that decided street names how did you come up with them? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/5y4l89/eli5_whos_in_charge_of_coming_up_with_street/ | {
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"In private developments in Ohio, it's up to the discretion of the developer. For example, the development I live in AND the street I live ON are both named after the developer's grandson... who lived in the development. The development I used to live in was interesting because every street was named after a winner of the Kentucky Derby. I would guess that the county commissioners name the public streets. This is probably different in all fifty states and I'm sure it's different in other countries. ",
"In my hometown streets named by developers, but town planners can veto. Once development is done, town is responsible for maintenance. \n\nAs a rule they never permit common first or last names (\"Katie Drive\") because the street signs would just get stolen.",
"I am not sure how heavily it's enforced anymore, but I believe that here in New Zealand the type of road (Street, Avenue, Road, Lane etc) used to be (may still be?) dictated by features of the location, while the unique part at the start was up to the land owner.\n\nI've always wanted to see a place called Lois Lane"
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2qz1dm | what happens to our mind when you spin around? | Why do we get dizzy when we spin around a lot and why is everything out of balance? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2qz1dm/eli5_what_happens_to_our_mind_when_you_spin_around/ | {
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"Nothing happens to your brain. You have fluid in your ear that helps your brain recognize what is up and what is down. When you spin the fluid has to re-equilibrate and while this is happening your brain is confused and the result is nausea, vertigo, and that weird effect where your eyes continue to follow whatever direction you were spinning in."
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263kwo | why is there two ways of writing "4" and "a" ? | Why is there two ways to write the lowercase "a" and why is there two ways to write the number "4" ? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/263kwo/eli5why_is_there_two_ways_of_writing_4_and_a/ | {
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"The '4' and 'a' you see on your screen right now (unless you're using an odd font) are the technically correct glyphs, which is why they appear that way in most typefaces unless it's specifically mimicking handwriting. The \"open 4\" is use in handwriting because it's easier to distinguish from a 9. When writing quickly, those two digits can often look similar. The other way of writing 'a' is more because it's easier and faster.",
"There are multiple ways to write any character. Just look at different fonts. It just so happens that in the case of a and 4, there are two popular main styles used in print which are very obviously different.\n\nOther equally obvious examples include 1, 7, g, w, l and z.\n\nIf you look at handwriting, the differences are way bigger.",
"The \"closed 4\" comes from the arabian formation of numerals where each numeral has the [number of angles as the number](_URL_0_), the \"open 4\", as far as I can tell, comes from the [lcd display](_URL_2_).\n \nAs for *a*s you have [double-story and single story](_URL_1_) the double story is more correct and used for cursive, but the single story was easier to make for printing presses."
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"http://upload.wikimedia.org/wikipedia/commons/thumb/f/ff/LowercaseA.svg/220px-LowercaseA.svg.png",
"http://www.solargauge.com/4kR4DClr.png"
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4ou24s | how are movies that were recorded in a lower definition able to be released in higher definitions? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/4ou24s/eli5_how_are_movies_that_were_recorded_in_a_lower/ | {
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"They were recorded on film, which isn't limited to an amount of pixels- for the most part.\n\nRemember that they were broadcast on a huge screen.\n\nAs long as you can get the original print you can re-release the movie as HD.",
"There are two reasons. One is that most movies are recorded on higher definition then they are released on. A lot of movies are recorded on film which have very high resolution. Even those scenes that are not as high resolution are still higher then the VHS and DVD releases because the movies use higher resolution film and the editing process might also reduce quality of the picture.\n\nSecondly a lot of the HD releases get a pass of post processing to artificially sharpen the picture and improve effects that could be done better with modern technology and higher standards for quality. Technicians will usually go through the movie frame by frame and add details and texture to make it look better. Sometimes entire scenes are redone if possible.",
"There is a lot of confusion here because \"high definition\" is a *television* standard, and movies are mostly on film. And as technology has progressed, we've been able to make television transmissions higher and higher definition.\n\nThat said: a movie camera 60 years ago produced a higher resolution product than any television you can buy today. Film has *very* high resolution.",
"They were recorded on film and then remastered with modern techniques. A lot of people think of film and think it is low quality, but film is actually incredible when it comes to quality, standard 35mm film being better than most digital sensors today. So when a film is rereleased, it is actually being rescanned at a much higher resolution than originally, because there never used to be a need for film to be scanned at say, 4K. So it is scanned, touched up to remove any scratches and often denoised to reduce bad film grain (a lot of which is left in, but sometimes it's too much and needs cleaned up). Now you're left with a very high quality digital file, more than capable of being watched in HD. ",
"I'll try to give a simpler answer. They weren't recorded in low definition, they were actually recorded in hi-defintion, they were just transferred to a low definition format because old televions and vhs technology had low resolution. So they just go back and re-transfer those movies to high definition for modern tvs and blu ray players."
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4oapyx | why does the us armed forces have an army, navy, marines, and coast guard, instead of just an army and navy. | It seems unnecessary to have all these branches when the Navy can just absorb the Coast Guard and the Army can absorb the Marines. To me it seems counter-intuitive for these specialized branches to exist when in reality they are essentially the same branch.
For example, Marines are supposed to specialize in invasion and ground combat, but so are Army Rangers. The Navy reigns in international waters but both the coast guard and the navy perform the same tasks with the same equipment.
To me, it seems expensive and overly complicated to keep 4 branches instead of 2. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/4oapyx/eli5why_does_the_us_armed_forces_have_an_army/ | {
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"Coast guard is department of homeland security. It has a shit ton of missions... Search and rescue, aids to navigation, drug and migrant interdiction, waterways management, pollution response and prevention port security etc etc etc... The navy does their thing and the coast guard does theirs.",
"The Marines (mostly) separated from the Navy when they started to be used as shock troops, and first engagement troops on mainland more often. They still operate as guards and boarding party combatants on naval ships though which is their historic role and specialization. \n\nThe Coast Guard was formed because the military is not allowed to operate on US soil or territorial waters outside of emergency or invasion. They cannot legally function as police for our water borders. They also do not have the same equipments, the coast guard does not have war vessels or nukes. \n\nThe Air Force split from the Army after the importance of air power was determined to be growing. They specialize in air defense, long distance strikes, and our missile systems. ",
"Back when they first started making militaries, there were two kinds of fighting people:\n\n* People who fought on land. When they got around to inventing the English Language, they called them *Armies*.\n\n* People who fought on water, from ships. We call them *Navies*.\n\nNow around the time of the American Revolutionary War (late 1770s), navies fought using wooden sailing ships with lots of cannons firing solid iron balls. These guns were pretty powerful, but they were pretty inaccurate unless you got really close, and unless you got really lucky and blew up the enemy's gunpowder magazine, they couldn't really do enough damage to sink another ship quickly. \n\nSo if you were willing to sail through cannonball fire for a little bit, it was possible to get close enough to the enemy ship to board it with your own men. However, most sailors were good at sailing, and not as good at shooting or hand-to-hand fighting, so they decided to create groups of soldiers who specifically trained to fight from ships. These are called *Marines*. \n\nSome countries kept them as part of their armies or navies, but in the US, they put them specifically under the authority of the Department of the Navy, and slowly over time they gained more and various responsibilities- Presidential guard, Embassy guard, etc. Also, because they were on Navy ships all the time, they were usually the first ground troops to show up when the government was trying to flex its power overseas, so they also started doing amphibious warfare (invading beaches from ships), which is their primary mission today.\n\nAround the same time, many countries saw a need for a nautical police force. Using the Navy for that was in most cases overkill; you want to enforce tariffs and catch criminals, not blow merchant ships out of the water. So *Coast Guards* started becoming a thing, tasked with seagoing law enforcement and search and rescue. In the US, it was put under the authority of the Department of Transportation in peactime, and the department of the Navy in wartime. (there was no Department of Defense then). Recently they've been put under the Department of Homeland Security.\n\nSo, finally, years later, airplanes were invented. Immediately all the armed forces saw a use for them; mainly spotting for big guns at first (Navy battleships and Army artillery), but later they started carrying guns and bombs and torpedoes and missiles. In some countries, they managed to create a separate *Air Force* right away (the UK did this with the RAF), but in the US, the Army and Navy each handled their own aviation, arguing (accurately enough) their needs were different. So it wasn't until after World War II that the Air Force was split off from the Army into a final branch. The Army still maintains its helicopters for transport and close air support, and the Navy argues that aircraft carrier operations are too different from the land flying that Air Force personnel are used to, so they each have their own aircraft. The Coast Guard needs aircraft for long-range search and rescue. And the Marines have their own aircraft because they're supposed to be a self-contained, independent and fast-moving fighting force once the Navy drops them on the beach.\n\nAs for why they haven't merged them back? Politics, money, and tradition. There have been several attempts made--the Air Force argued in the 50's that nuclear weapons made all surface forces obsolete; the Army has tried to absorb the Marines several times; the Air Force has tried to take the Navy's planes, etc. But it seems unlikely in the near future."
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d0enst | What happens to bones when a big animal like a shark or an orca eats and swallows another whole animal? | I've seen several times how an orca eats a whole seal with one bite and then swallows it completly.
But how does it digest the whole animal including all the bones? | askscience | https://www.reddit.com/r/askscience/comments/d0enst/what_happens_to_bones_when_a_big_animal_like_a/ | {
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"Sharks have a digestive system that's designed to primarily digest meat and fat, so larger bones, chunks of sea turtle shells, things like that are usually vomited back out. \n\n\nAnd orcas have a three-chambered stomach, so the food takes more times to pass through, and gives the stomach acid more time to digest everything, including bone"
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e1txf4 | how do hooves make animals better at climbing mountains? | Wondering how mountain goats are so good a climbing. How to hooves help them? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/e1txf4/eli5_how_do_hooves_make_animals_better_at/ | {
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"Mountain goats have special hooves that are like a pirate's hook with soft padding to help adjust. They suck at running long distance running but are great at scaling verticle surfaces because of this.",
"From what I’ve read the two hooves in the front of each foot has a hard edge able to grip the rocks and a soft center pad. A sort of combo of a cats claw (gripping with sharp edge) and horse hoof (soft bottom for traction) the hooves can move independently to help it climb. _URL_0_",
"If climbing and you stand on a small edge (a bit of rock sticking out that's anything from a couple of inches wide down to a few millimetres), when you put weight on it in bare feet or trainers the sole will bend as its flaubert and your weight is distributed across the whole area, most of which is unsupported.\n\nClimbing shoes And, more relevant to hooves, mountaineering boots, have much more inflexible and solid soles. Mountaineering and walking boots even have a scale of hardness/inflexibility - b1 to b3 with b3 being totally inflexible. These allow you to put a tiny area of the boot on an edge and put your weight on it.\n\nHooves are the same as in they are far more solid and inflexible than eg paws."
]
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[],
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"https://www.core77.com/posts/18851/biomimetic-designers-take-note-goat-hooves-confer-ninja-like-climbing-abilities-18851"
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gbpm4 | Would phlegm be digested if swallowed? | Our stomach is lined with mucus that protects out stomach wall from digesting itself. So, the stomach mucus must not digestible. Does this mean that if I were to swallow my nasal mucus, it would just sit there until I poop it out? | askscience | http://www.reddit.com/r/askscience/comments/gbpm4/would_phlegm_be_digested_if_swallowed/ | {
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"text": [
"The mucous is digested further down in the gut by enzymes in the small bowel and bacteria in the large bowel. "
]
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8k7ok2 | Have there been periods of greater or lesser volcanic activity on earth, and if so, what causes this variation? | askscience | https://www.reddit.com/r/askscience/comments/8k7ok2/have_there_been_periods_of_greater_or_lesser/ | {
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"In the past there have been more volcanic activities since the Earth was much hotter after accretion. The whole surface would have been a barely cooled crust covered in volcanic pustules. \n\nIt was much hotter and we have evidence of it from komatiiates which only form at higher temperatures than we see today (1). \n\nSo during the early Earth was more volcanically active but different from the volcanoes we see today. \n\nAnother thing that continues to influence volcanic activity is thought to be glacier cover. The increased pressure on the volcano from meters worth of ice can depress eruptions (2). \n\nReferences: \n1. _URL_0_\n\n2. _URL_1_",
"Yes, with important implications for both global tectonics and the climate system. To talk about volcanism, let's start with heat, seeing as that's what drives it all. \n\n\nAssuming that the composition of the bulk Earth is similar to that of chondritic meteorites (a standard assumption, though geochemists like to argue over the finer details), exponential decay of the heat producing isotopes of potassium, uranium and thorium suggests that total heat production was significantly greater in the early Earth. \n\n\nThe greatest uncertainties are the contribution of ⁴⁰K, because some potassium may have been lost at the time of Moon formation and the amount of heat retained from that event, as well as from initial accretion and core formation. These factors all contribute to estimating the variation of heat flow over geological time. Another important factor is the occasional contribution of heat by very high-powered impacts in the past, the largest such extraterrestrial heat delivery having been between 4100 and 3800 million years ago (the late heavy bombardment).\n\n\nDespite the difficulties in quantifying all of the above, estimates put the Earth's early heat flow between 10 and 4 times greater than at present when the first continental rocks formed 4000 Ma ago and at the end of the Archean (2500 Ma) respectively. \n\n\nArchean lavas erupted at unusually high temperatures by today's standards then, promoting a larger degree of partial melt and thus a larger volume overall. This is the time during which the 'cratons' formed - the stable interiors of the continents, which are thought to have grown rather rapidly compared to the sluggish production of continental crust today. \n\n\nBut the Archaen overall spans 2.5 billion years. If you're looking for something a bit more localised in time, then we should talk about flood basalts. \n\nAccumulations of lava flows with basaltic composition cover large parts of the Earth. Some of the statistics are impressive: India’s 66 million year old Deccan Traps cover 0.5 million km² and may have covered 1.5 million km² when first erupted. They have an average thickness of at least one kilometre. Most of their huge volume may have been erupted in less than 0.5 million years (although this is controversial) and they may consist of many hundreds of individual lava flows. On erosion, they acquire a distinctive topography resembling [flights of steps.](_URL_0_)\n\n\nIn northwestern USA, the Columbia River Province consists of 240,000 km³ of flood basalts erupted between 17 and 12 million years ago, in individual flows 20–50 m thick, covering an area of more than 200,000 km². Approximately 90% of the total volume of the province might have been erupted during a period of less than 1.5 million years between 16.5 and 15 million years ago. Work on individual eruptive units of basalt lava in the Columbia River Province has shown that > 1000 km³ could have been erupted in continuous, individual eruptions lasting a decade or longer. \n\n\nAt any given time in Earth history, the amount of carbon dioxide in the atmosphere is the result of the balance of fluxes between sources and sinks in the carbon cycle. If the average global flux of carbon dioxide to the atmosphere from volcanoes should increase for some reason, and if that increased flux is sustained, then the carbon cycle will settle into a new equilibrium with a warmer climate. ",
"Well, we have some pretty good answers. If you want a discussion on glaciers and impact volcanoes post another question! It is a relatively new avenue of research.\n\nAs others have mentioned the Earth (internally) was hotter in the past and hence was more active volcanically. \n\nThe rest is a little harder to piece together. There is evidence for a series of mantle plumes shortly after Pangea broke up, deccan traps, Yellowstone hot spot, Hawaiian-emperor hotspot, Icelandic hot spot to name a few. The new oceanic crust displaced sea water on to the continents creating epeiric seas. It was definitely a time of more volcanic activity. \n\nI have not studied this directly but one theory is the super continent Pangea acted as an insulator causing heat anomalies beneath it which helped to bring about these mantle plumes. All are a similar in age. "
]
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| []
| [
[
"https://www.nature.com/articles/1779",
"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5654763/"
],
[
"https://i.imgur.com/6OOMP1E.jpg"
],
[]
]
|
||
3vf6ts | Have there ever been memes similar to the modern memes? | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/3vf6ts/have_there_ever_been_memes_similar_to_the_modern/ | {
"a_id": [
"cxmzwjy"
],
"score": [
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],
"text": [
"\"Kilroy was here\" is the only thing I can remember. Basically, during ww2 American soldiers would leave these marks on beaches they stormed, places they visited, etc."
]
} | []
| []
| [
[]
]
|
||
5jzy0n | nuclear arms race | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/5jzy0n/eli5_nuclear_arms_race/ | {
"a_id": [
"dbk8xls",
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"text": [
"they dont just stockpile the same type of nuke, with time other nations can come up with newer and better delivery methods that cant be stopped or intercepted or your older nukes become incapable of delivering/entering the target area so they make more nukes with better technology.\n\nsometimes they upgrade previous systems , other times its complete new systems.\n\nsince those weapons dont ever get used they stock pile into the thousands.",
" > So if X amount of nuclear weapons are enough to completely wipe a country off the map, then what changes if you get more? Nothing, right? It's redundant?\n\nRedundancy is important. The goal of a theoretical \"first strike\" is to knock out the capability of your opponent to return fire. This means a lot of nuclear weapons are targeting the launch silos of other nuclear weapons. More nuclear weapons then makes it harder for an enemy to reduce your weaponry below the threshold of acceptable losses. If you only have precisely enough weapons to destroy an enemy then anything they can destroy before they reach their target is a reduced impact, but overkill means it doesn't matter.\n\nAlso, what if a nuclear war breaks out and you \"win\"? Now all your nukes are expended and you are defenseless! There *are* other nuclear powers out there you know. You want enough nukes to destroy your enemy even if you lose a portion to unknown defenses or surprise first strikes, plus enough to protect yourself after a conflict presuming you succeed."
]
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| [
[],
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|
||
utknx | Can any scientists comment on the debate in /r/science regarding a new Alzheimer's vaccine? | Basically, some people think that this article means a new vaccine has been found, while others are saying that all the trial shows is that people didn't die from the vaccine. I now have friend's posting the story on their facebook, so I'd just like to know if its legit or not before people get their hopes up too much. A lot of us have loved one's who are or were afflicted by this terrible disease :(
reddit thread: _URL_0_
story: _URL_1_ | askscience | http://www.reddit.com/r/askscience/comments/utknx/can_any_scientists_comment_on_the_debate_in/ | {
"a_id": [
"c4yew06"
],
"score": [
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"text": [
"Based on the abstract (for some reason my institution doesn't have access to the full paper) of the [Lancet Neurology paper](_URL_2_), I'm not too impressed. This was an extremely preliminary study establishing the side effect profile, as well as determining whether the vaccine actually induces an antibody response. According the abstract, they didn't even look at efficacy in their outcomes. Their overall conclusion was that 1) this vaccine does induce some sort of immune response and 2) it doesn't seem to have serious adverse effects. They listed \"Immune response, cognitive and functional assessments\" as one of their secondary outcomes on their [_URL_1_ page](_URL_0_), but don't report on it in the abstract.\n\nAs this was merely a phase I trial, the n is also very small (58 total). I think it's quite a number of steps from anything clinically useful.\n\nedited to add: the principle that they're working with is inducing antibodies against the Aβ-amyloid. I'm not convinced that this would actually be effective. Aβ-amyloid makes up the 'senile plaques' that is so characteristic, but I don't think it's very indicative of cognitive defects. I think the tau proteins (that make up the neurofibrillary tangles) are much more prognostic. I'm also not convinced that an antibody response against these plaques would be helpful, since they would have to penetrate the blood-brain barrier to reach the amyloid. Once there, it's not like the antibodies magically make them go away, since there would still need to be some mechanism of clearing them (possibly via microglia). So I guess my point is that this is an important step towards eventually possibly developing a vaccine or treatment, but there's so much that we don't know yet that it's hard to see it happening in the near future."
]
} | []
| [
"http://www.reddit.com/r/science/comments/usr9l/alzheimers_vaccine_trial_a_success/",
"http://ki.se/ki/jsp/polopoly.jsp?l=en&d=130&a=145109&newsdep=130"
]
| [
[
"http://clinicaltrials.gov/ct2/show/NCT00411580",
"clinicaltrials.gov",
"http://www.lancet.com/journals/laneur/article/PIIS1474-4422%2812%2970140-0/fulltext"
]
]
|
|
1s9e2l | how are people/groups of people legally allowed to place "bounties" on others? | For example the NYC Jewish community offering bounties for people involved in the knockout game or the Black Panthers offering a bounty for George Zimmerman. How is that legal?? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1s9e2l/eli5_how_are_peoplegroups_of_people_legally/ | {
"a_id": [
"cdv837c"
],
"score": [
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"text": [
"They're not \"bounties\" like in the Boba Fett sense. They're rewards to turn over information which would lead to arrest/prosecution. Boba Fett bounties (\"Capture and/or kill this person\") are illegal."
]
} | []
| []
| [
[]
]
|
|
4306vm | lots of people barely eat vegetables and never take multivitamins, and still seem to be in good health. how is the daily recommended amount of micronutrients calculated, and why do people seem just fine even if they don't get it? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/4306vm/eli5_lots_of_people_barely_eat_vegetables_and/ | {
"a_id": [
"czefph9",
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"text": [
"Pretty much everyone in a developed country gets enough nutrients to stay reasonably healthy unless they are on some kind of super restrictive diet.\n\nThe RDA's are *very* conservative and you have to be *very* deficient for a long time before you'll start seeing serious health effects.",
"One big thing is that we have a lot of vitamin enriched foods. Rice, pasta, flour & bread - pretty much anything coming from grains - are almost always fortified with nutrients. Milk is widely fortified with vitamins A & D.",
"Holy fucking shit. Great minds think alike. Dude I was just gonna ask this same question TODAY I kid you not. "
]
} | []
| []
| [
[],
[],
[]
]
|
||
dkmtri | If gravitons exist, then is it possible for anti-gravitons to exist and would that mean that the matter they interact with will gain negative gravity? | askscience | https://www.reddit.com/r/askscience/comments/dkmtri/if_gravitons_exist_then_is_it_possible_for/ | {
"a_id": [
"f4iar2p"
],
"score": [
31
],
"text": [
"The graviton would be its own antiparticle in the same way that the photon is also its own antiparticle. No negative gravity needed."
]
} | []
| []
| [
[]
]
|
||
rbr9i | How does a globe storm glass barometer work? | I know that the water level changes when the air pressure changes, but how the water level change within the globe that is not exposed to the atmosphere? I don't understand how the water in the globe changes if there is no air going in or out of the globe.
My [storm globe](_URL_0_) | askscience | http://www.reddit.com/r/askscience/comments/rbr9i/how_does_a_globe_storm_glass_barometer_work/ | {
"a_id": [
"c44iy3a"
],
"score": [
8
],
"text": [
"It is open to the atmosphere! That glass pipe off to the side is open, and when the air pressure increases it pushes down on the fluid in the pipe. Through the wonderful nature of hydraulics, the water in the globe then rises. "
]
} | []
| [
"http://i.imgur.com/uNXmS.jpg"
]
| [
[]
]
|
|
vpfgg | What happens to a morbidly obese individual during hydrated starvation? | And how long could a morbidly obese individual survive without food, and with only minimal amount of water? | askscience | http://www.reddit.com/r/askscience/comments/vpfgg/what_happens_to_a_morbidly_obese_individual/ | {
"a_id": [
"c56hicf"
],
"score": [
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"text": [
"Similar - and I emphasize SIMILAR things have been done, although I frankly don't know where to find the study. Googling might pull up something for you. \n\nThey took a fat dude, kept him supplied with fluids and vitamins and the like, and successfully kept him alive and relatively well. Think he lost a totally insane amount of weight, too."
]
} | []
| []
| [
[]
]
|
|
v9aqs | Is it possible for a planet to exist in our SS that we have yet to discover? | With technology the way that it is, I'm assuming we know without a shadow of a doubt exactly what's within our solar system. So my question is if its even possible for us to have missed something? Maybe a planet that is on the same (or a very similar) orbit as the earth, but constantly on the opposite side of the sun, rendering it invisible? | askscience | http://www.reddit.com/r/askscience/comments/v9aqs/is_it_possible_for_a_planet_to_exist_in_our_ss/ | {
"a_id": [
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"score": [
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"text": [
"No, any body large enough to be a real planet would leave a gravitational footprint that could be observed. ",
"There was actually an idea that there might be a planet on the opposite side of the sun from the Earth, the estimated effects it would have on Mars and Venus were not observed. Various images of the sun from different angle from Earth have also given no evidence to a \"hidden planet\".",
"It is likely we will discover more [Trans-Neptunian](_URL_0_) dwarf planets."
]
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| []
| [
[],
[],
[
"http://en.wikipedia.org/wiki/Trans-Neptunian_object"
]
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|
|
2emmi2 | why do radio stations sometimes have two frequencies playing the same thing? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2emmi2/eli5_why_do_radio_stations_sometimes_have_two/ | {
"a_id": [
"ck0zz9e"
],
"score": [
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"text": [
"They would probably be broadcasting from different locations, giving the station a wider range."
]
} | []
| []
| [
[]
]
|
||
s5nyd | Is there any known species that can see other parts of the electro magnetic spectrum? | askscience | http://www.reddit.com/r/askscience/comments/s5nyd/is_there_any_known_species_that_can_see_other/ | {
"a_id": [
"c4baqqw"
],
"score": [
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"text": [
"Tarsiers and Chameleons can see in the Ultraviolet. Dragonflies can see polarized light (Not a different part of the spectrum, but still cool). The Mantis shrimp is my favorite though. It has the most complex eyes known in the animal kingdom. Like many flies the mantis shrimp has compound eyes, but each row of ommatidia have specific functions (i.e. one for light intensity, one for color, etc) Their eyes have twelve different types of color receptors (humans only have three) as well as Ultraviolet, Infrared, and polarized light. Let me also say that it doesn't necessarily help to see light in other parts of the E/M spectrum except infrared because although stars emit light from ultraviolet to radio, about 50% of the light is in the visible range and about 20% is infrared."
]
} | []
| []
| [
[]
]
|
||
a9p29l | why do your lips peel when you’re sick? | Currently sick and pissed because my lips hurt | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/a9p29l/eli5_why_do_your_lips_peel_when_youre_sick/ | {
"a_id": [
"ecl74a2",
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],
"score": [
3,
3
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"text": [
"lip skin is different than regular sin & doesn't make it's own lipid.\n\nIt comes from the skin around your lips & those pores could be clogged. As an experiment you could try AHA cream on that skin, or just get good chapstick.",
"I think it may be a combo of dehydration and breathing more through your mouth if your nose is stuffy. \n\nDo you have a good chap stick? Burts Bees or something similar can be a game changer. Olive oil could also help."
]
} | []
| []
| [
[],
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]
|
|
yac4f | Japan was separated from their Axis allies by numerous Allied countries. How did they communicate with other Axis powers? | Map [here](_URL_0_)
Also, anyone know what that little country to the northwest of Mongolia is? I know today that would be part of Russia. | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/yac4f/japan_was_separated_from_their_axis_allies_by/ | {
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"text": [
"The little country is Tuva.\n_URL_0_",
"I read somewhere that Germany gave them an Enigma machine.",
"For the most part, they didn't. Top axis and allied leaders met and hammered out agreements at conferences. The Axis leaders often didn't even tell each other which countries they were going to invade, much less had joint strategy sessions.",
"There were plans to fly long-range versions of the Junkers JU290 to Japan. By starting in northern Finland the Junkers would just be able to reach Japanese occupied China without re-fueling.\n\nThere are some secondary sources that claim these flights did take place, both to carry messages and VIP passengers. Certainly not enough evidence to be conclusive.",
"- Shortwave radio. The Japanese embassy in Berlin had a \"Purple\" cipher machine, believed to be unbreakable throughout the war (this is the code that was broken by American cryptanalists helping the US prepare for the Battle of Midway). Even the Germans knew that it was probably exploited as early as 1940. They also used a cipher called \"RED\", also broken by WWII. The Japanese military (army and navy - the Navy had its own code named JN-25) did not trust the foreign office all that much and subsequently didn't tell them a lot. The Japanese also used an Enigma machine model 'T' ('Tirpitz'), as well as Enigma-C (commercial) variants. I am not sure whether these were broken. There was also a rarely used Enigma variant called \"GREEN\". The Germans used various Enigma models, as well as a cipher called \"Floradora\" (broken 1941-1942). I am not sure whether they used any Lorenz machines.\n- VLF (also frequently used to communicate with submarines at sea). [Here is an example of a Japanese transmitter](_URL_6_) that is still standing. I am unsure whether that was still used during the war.\n- Long-range cargo submarines, both Japanese and German. The Japanese [I-8](_URL_3_) and [I-52](_URL_5_), and German [U=234](_URL_4_) and [U-864](_URL_0_) were examples of these; of this list, only I-8 was successful (the wikipedia page lists others). There were several others, for example the Italian [Commandante Capellini](_URL_1_). In Japan, these missions were known as \"Yanagi\" (Willow). \n- Diplomatic staff already on location. For example, a major economic cooperation agreement was signed in 1943, fixing things like the Yen-Reichsmark exchange rate. Due to the difficulty in transporting large, bulky supplies (like steel, which the Germans were loth to part with anyway), transports were limited mainly to high-tech components, technical plans, and rare materials. [Wikipedia also mentions rising deception](_URL_2_) as each participants' war fortunes ebbed. These staff obviously had to communicate with their home country (see the other points in this list), but had a fair amount of leeway in terms of procedure and negotiations.\n- Land lines over neutral countries. Remember that Japan and the USSR only went to war in late 1945. As such, the Japanese had access to the same infrastructure used to communicate with their Moscow embassy. From there, via Turkey (the Soviet-Turkish border was never taken by the Germans, and the Soviets continued to communicate via Turkey.)\n"
]
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"http://en.wikipedia.org/wiki/File:WWII.png"
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| [
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"http://en.wikipedia.org/wiki/Tuva"
],
[],
[],
[],
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"http://en.wikipedia.org/wiki/German_submarine_U-864",
"http://en.wikipedia.org/wiki/Italian_submarine_Comandante_Cappellini",
"http://en.wikipedia.org/wiki/Germany%E2%80%93Japan_relations#Japan_enters_World_War_II",
"http://en.wikipedia.org/wiki/Japanese_submarine_I-8",
"http://en.wikipedia.org/wiki/German_submarine_U-234",
"http://en.wikipedia.org/wiki/Japanese_submarine_I-52_%281943%29",
"http://yosami-radio-ts.sakura.ne.jp/english/contents/memory_yosami.html"
]
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|
|
22hj74 | what is the purpose of so much pollen everywhere? | I get that the more pollen the more likely fertilization will happen, but not every place has the same pollen levels...and also most places don't seem to have anymore plants than others with more or less pollen. So why do plants give off so much pollen? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/22hj74/eli5_what_is_the_purpose_of_so_much_pollen/ | {
"a_id": [
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" > So why do plants give off so much pollen?\n\nTo make sure they have enough. Way out on the edges of the most distant spread of the pollen there may be just enough for fertilization, and the ground covered increases greatly as they put more and more out there. It isn't a group effort; each tree is trying to spread its genes individually. It doesn't matter if other trees have \"enough\" pollen, it matters if they have the pollen of a given tree."
]
} | []
| []
| [
[]
]
|
|
4rg48u | How can a counterexample to the Collatz(3n+1) conjecture be for a sequence to go towards infinity? | According to this video _URL_0_ and other people, one way that the Collatz conjecture could be disproved is by finding a number that creates a loop such as 4 - > 2 - > 1 - > 4 - > 2 - > 1 ... or by finding a number that wanders off to infinity. What I don't understand is how it's even possible for any sequence to keep growing, given how the conjecture works. It states that every even number is divided by 2, and every odd is multiplied by 3, and then added by 1. So if you take any number, there's a 50% chance of it being even, and a 50% chance of it being odd. For every even number, there's a 50% chance that you can only divide by 2 one time. (2,6,10,14,18,22...) So every even number (after division by 2) has a 50% chance of becoming even, and a 50% chance of becoming odd. As for the 3n+1 part, that has a 100% chance of becoming an even number when n is odd. If evens have a 50% chance to become even again, and odds will always become even, it would seem that no matter what, you're always going to end up dividing by 2 more than you're going to be doing 3n+1. Would that not be a 2/3 chance to become even? Which would then mean it can't keep increasing forever?
If this post made you facepalm in any way, I apologize, I'm no mathematician. | askscience | https://www.reddit.com/r/askscience/comments/4rg48u/how_can_a_counterexample_to_the_collatz3n1/ | {
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"You can't use statistics on math. For example, half of numbers are even, but there's only one odd power of two, and only one even prime. Similarly, you might end up getting (3n+1)/2 as being odd over and over again even though it statistically shouldn't happen.",
"Your argument is an example of a \"heuristic\": you reason what happens on average and that suggests what *should* happen in general. A lot of times you use a heuristic to guess at a result, but then you need a proof to make sure it really works.\n\nThe Collatz conjecture is interesting because, while it seems obvious you should always get 1 at then end, no one's been able to prove it.\n\nI'm also not sure if your probabilities are right, but I need to eat something before I write any more.",
"Have you ever looked at the Collatz sequence when the starting number is 27 ? Here it is :\n\n27, 82, 41, 124, 62, 31, 94, 47, 142, 71, 214, 107, 322, 161, 484, 242, 121, 364, 182, 91, 274, 137, 412, 206, 103, 310, 155, 466, 233, 700, 350, 175, 526, 263, 790, 395, 1186, 593, 1780, 890, 445, 1336, 668, 334, 167, 502, 251, 754, 377, 1132, 566, 283, 850, 425, 1276, 638, 319, 958, 479, 1438, 719, 2158, 1079, 3238, 1619, 4858, 2429, 7288, 3644, 1822, 911, 2734, 1367, 4102, 2051, 6154, 3077, 9232, 4616, 2308, 1154, 577, 1732, 866, 433, 1300, 650, 325, 976, 488, 244, 122, 61, 184, 92, 46, 23, 70, 35, 106, 53, 160, 80, 40, 20, 10, 5, 16, 8, 4, 2, 1\n\nAs you can see, even if eventually it goes back to 1, the sequence grows for a pretty long time. There is no known obstruction that would rule out a sequence that would grow forever. \n\nYou could perhaps make your argument with probability more precise to try to prove something like \"most numbers go back to 1\". But the probability statement is not enough to prove that it's true for ALL numbers. "
]
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"https://youtu.be/K0yMyUn--0s?t=413"
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7n08xw | What did Vikings do with all their loot? Was the loot divided equally among the raiders, given to one man, or somewhere in between? | If it was brought back to Scandinavia, did the influx of loot have any impact on the economy of the region? Perhaps encouraging more trade? | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/7n08xw/what_did_vikings_do_with_all_their_loot_was_the/ | {
"a_id": [
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"text": [
"It certainly did. I recently finished my masters on these lovely individuals and while I do not have all the sources handy with me, hopefully, someone else here will. \n\nTo give you a brief, non-cited explanation, there were several places that the loot from Viking raids/expeditions had a serious effect. Towns like Dublin were completely established by Viking raiders and therefore would have been affected greatly by the influx of coinage. In addition to that, those Vikings that served in the Varangian Guard and returned to Iceland often did so as rich men. I believe there is a man named Bolli Bollason (or something similar), who serves for a time in the Varangian guard, then returns and is so wealthy he is known as Bolli the Grand. \n\nAs far as the division of loot goes that is a much harder and less studied question. There are no primary sources that give us a percentage break-down of what a raiding band would receive. Often, all we have is that the entire force was paid x pounds of silver and other such goods. In order to really find out something about how much the average Viking warrior took home would require examining graves. Even then though, it would only be a rough estimate of how much a raider could obtain over time and not be an accurate reflection of how much a particular raid earned them. \n\nI can promise you though, it is *very* unlikely that only one man received the loot, and even if he did, he soon split it up amongst his men or else paid the price. Gift giving was extremely important and played a massive role in keeping together raiding parties. \n\ntldr: very much yes. "
]
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61qxca | we have a huge sea which is evapourating all the time which comes back to us in the form of rains. we can create artificial rains. why do we worry about water shortage in future? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/61qxca/eli5we_have_a_huge_sea_which_is_evapourating_all/ | {
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"We can not create rain from nothing. We are able to seed rain clouds so that the water falls down before it normally would. The problem is that farms require water over a large area which increases evaporation before the rivers are able to get to the sea. If you were to create artificial rain over the farms to water the crops instead of using the rivers that supplies water to the downstream areas there would be less rain upstream and the rivers would still dry out.",
"First of all, I'm not sure what you mean by creating \"artificial rains.\" It's possible to seed clouds and make them rain, but it costs money, and only works if there's sufficient moisture available. We can desalinate saltwater, but it's expensive and time consuming. Personally, I think that it's a really important scientific pursuit and more people should be working on the problem of how to do it cheaply, but as it stands, turning saltwater into freshwater is not easy or cheap to do at volume.\n\nSo, what we're left with, you may be surprised to hear, is 2.5% of the earth's water. That's what percentage is NOT saltwater. Of that, less than half is easily accessible (from lakes, rivers, or aquifers close enough to the surface for wells). We're talking 1% of the planet's water is not salt and available for people to reach. Now, if we let industry dump waste products into that water, we have less and less potable water for future generations, and we have to invest more and more money into cleaning up the freshwater that's available to us. \n\nNow, we're looking at a population that continues to expand. Many people are already at a disadvantage when it comes to acquiring water. They either live in arid regions where there is little freshwater to start with (that's another problem with desalinating saltwater--it's terribly expensive to ship it to people who don't have access to water) or else in places where there is little water regulation, and the \"fresh\" water available to them is dangerous to drink. \n\nEvery year, the planet's water usage increases. There are more people, more factory farms, more industry. This all decreases our available freshwater, as do the increased pollution that comes with an increased population. Now we have situations where places that already experience drought/water shortage find that industry has more right to the water than people do. We have companies like Nestle pumping water out of drinking sources, bottling it in plastic (and I'm pretty sure the plastic industry uses a lot of water, too), and selling it back to people. \n\nIf you have a good idea for taking large quantities of saltwater and purifying it quickly and inexpensively, you should get on that right away, because you will save lives and probably get rich. But don't believe, right now, that humanity has an unlimited supply of drinking water at its fingertips, because we don't. It's limited and shrinking and if corporations like Nestle have their way, water won't be a human right anymore. It will be an expensive privilege. ",
"We cannot create artificial rain. Why do you think we can? \n\nWater shortages are about droughts at specific local levels, or consumption being higher than supply of fresh water. "
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1n3odz | is artificial photosynthesis not viable? | Quick search on ELI5 gave nothing, Google gave me a few results about recent successes, but no reason why it isn't used. Getting rid of carbon dioxide would generally seem to be a pretty good thing right? Oxygen and glucose are also *fairly* useful things.
Have we simply not yet figured out how plants do the thing? Does it use too much energy or take too much time?
| explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1n3odz/eli5_is_artificial_photosynthesis_not_viable/ | {
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"Photosynthesis (PS) involves harnessing light (photons) from the sun for energy to drive chemical reactions. Here's an abridged version of the process:\n\n1. A photon strikes an electron that is chilling in chlorophyll (or some other pigment depending on the wavelength of light the organism harvests)\n2. The electron absorbs the photon\n3. The electron gains the energy of the photon, becoming 'excited'\n4. The excited electron is chemical reactions that require a lot of energy (called 'energetically unfavorable reactions')\n5. The cool part: light is used to split water into oxygen and hydrogen and build carbohydrates from CO2\n\nWhen the excited electron forms a new chemical bond, that chemical bond stores the energy of the excited electron. That stored energy can be used to drive other energetically unfavorable reactions, many of which happen at night. These are aptly called the dark reactions (the reactions involved in harvesting light for energy are called the light reactions).\n\nWe know pretty well how PS works, but we're nowhere near technologically advanced enough to replicate the process artificially. There are tons of steps involved in harnessing that light energy - sort of like taking the stairs from the top floor instead of jumping off the roof. Each step is a separate chemical reaction facilitated by a unique protein. It's hard to build that from scratch.\n\nHere's a simple breakdown of the process: _URL_0_\n\nOne last thing: the majority of carbon fixation (utilizing atmospheric CO2) is done by microorganisms, especially marine microorganisms. Scientists are trying to genetically modify photosynthetic microorganisms so they'll take atmospheric CO2 and convert it into useful organic compounds like ethanol and other biofuels.\n\nI lied, here's the last thing:\n > Chlorophyll? More like BOREophyll!\n\n > Right?",
"Plants (and others) are extremely efficient!! (as are all living things/enzymes) We have a general understanding of how this process works, but have yet to do this synthetically.\n\nWe have been able to make photoactive catalysts that assist in the splitting of water, but there is still an overpotential necessary for the reaction. (overpotential: additional energy/electrical current needed)\n\nWe have also started working on catalysts that will take CO2 from the air and convert these into methane, methanol, ethanol, etc. The problem here is that catalysts that do this get \"poisoned\" by intermediates or product. \n\nMy general understanding is certain metal surfaces (Cu, Au, etc) can catalyze CO2 into hydrocarbons. But the one intermediate carbonmonoxide (CO) can bind so strongly that forward reactivity is halted, or it binds so weakly that it falls off before further reactivity can occur. And we don't want to make a bunch of CO!\n\nThere is fundamental research currently ongoing that is looking at alloys of metals and non-crystaline metals for this catalysis. The hypothesis is that certain metal surfaces are good at breaking CO2 into CO and others are good at taking CO and making it H2CO or even more complex (and useful) chemicals.\n\nHope this helps a little.",
"to your point about getting rid of carbon dioxide being a generally good thing:\n\nnot really. the less co2 there is in the athmosphere the slower plants grow and the less co2 they get out of the athmosphere themselves because of this. it's like trying to evaporate all the water in the sea, it would just rain more."
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rjvhh | Would a handful of marbles released in empty space exert enough gravity on each other to clump together or even orbit one another? | askscience | http://www.reddit.com/r/askscience/comments/rjvhh/would_a_handful_of_marbles_released_in_empty/ | {
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"If they were released in a perfect vacuum infinitely far from any other gravitational force, so that the only force any of them experienced was from the other marbles, then yes they would clump together. Depending on their distance it may take an obscene amount of time, but lacking any resistive forces they would very slowly accelerate towards one another. Whether they'd make contact before the universe decided to end would be another matter.",
"If you started them off stationary with respect to one another, they would move together and end up in a clump, because their only acceleration would be towards one another. Of course, the accelerations would be very small, and the time to clumping very large.\n\nIf you started them with velocities with respect to one another, they could enter orbit, clump together (or at least hit each other, with behaviour depending on the elasticity of the collision), or move apart forever depending on what those velocities were. My quick calculation suggests that escape velocity for a 5g marble at a distance of 5cm is about 4 microns per second.\n\nEdit: I confirmed my escape velocity calculation using [Wolfram Alpha](_URL_0_). At a distance of 5cm from a relatively heavy 5g marble, it's about 4x10^-6 metres per second. So each marble wouldn't need much velocity to escape the others."
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4btgkp | how can most low-end phone have a better processor speed than higher-end laptops? | My younger brother is looking at buying a new smartphone so I've been looking at some possibilities for him. What has amazed me is the sort of processor speeds that most low-end (£100-200) smartphones have compared to a higher-end computers.
For example, I have looked at the Huawei P8 Lite:
1.3 GHz Octa-Core (£99 at Carphone Warehouse)
Sony Xperia M4 Aqua:
1.5 GHz Quad-Core + 1.0 GHz Quad-Core
I understand that these will not reach the potential combined speed of the cores (about 10-11 GHz) due to the lack of 4/8 Core multitasking functionality in mobile apps but still, that potential speed is massive.
Compare this to the processor of my laptop (Toshiba S50-B-15P):
2.40 (3.00 Turbo) GHz Dual-Core
How can my computer run so much faster and cost so much more yet only have a potential maximum speed of 4.8/6 GHz, almost half that of these low-end phones? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/4btgkp/eli5_how_can_most_lowend_phone_have_a_better/ | {
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"let me make this music analogy when comparing cpu's of vastly different architectures.\n\n1. cpu speed (aka mhz) is only used to synchronize the various components within a cpu. it is essentially a metronome. a faster or a slower metronome doesn't tell you anything except the beat of the music aka bpm (beats per minute)\n\n2. more cores means more people playing in the band. it doesn't mean they would get more work done or do the work faster. it only tells you how many people there are. what is important here is how skilled the people (cores) are. and that is determined by the cpu architecture. which we don't know.\n\n3. so in order to determine which is the better cpu. we have to have them perform music (aka use a benchmark). in a musical performance, not all members of the band are playing all the time, just like in a benchmark. \n\nso when you go to judge whether a band is good or not, you don't look at their music's bpm, and you don't look at how many people there are. you have them play and you listen (aka running a benchmark). ",
"They are different architectures and run different types of operating systems, they don't compare at all.",
"number of cores and clock speed (GHz) do not necessarily indicate raw processor power. You also cannot add the GHz of multiple cores to get a number that means anything.",
"Previous answers are correct.\n\nThe gigantic cores in a laptop CPU do much more work per GHz, and per core, than the modest cores in a phone CPU. They do this using a range of tricks to ensure that at least one operation -- sometimes two or more -- will be completed nearly every time the clock ticks.",
"There is A LOT of things that are wrong with your statement, but Ill tackle the cores myth:\n\nmore cores =/= more power\n\nyou have one pregnant women, assign that task to 8 women...will they deliver the baby faster? No.\n\n**Lets deliver that baby!**\n\nIn your scenario since you have 1.3GHz(assume 8 cores), we would only use one... one super slow core.\n\nIn your laptop we will use one 2.4GHz(3.0 turbo) core, in this scenario the laptop will be faster.\n\nNot everything is coded to be divided into multiple cores. In reality most programs are run in only one, sometimes 2 cores. (2 is becoming more standard nowadays, while 4 is quite rare)",
"A full explanation is very complicated, but basically GHz is *not* a good way to compare processor speeds unless all kinds of other things are kept constant, and between cell phones and laptops they're *not*.\n\nFirst of all, more cores are not as good as one faster core, so your simple addition is fallacious. They're of some help (which is why they're included at all), in some situations, but it's not linear. As the joke goes \"it takes 9 months to make a baby, no matter how many women are assigned to the the task\". Likewise, more cars won't shorten your daily commute; it's only if you have to transport a lot of people that additional cars are useful.\n\nSecondly, the memory subsystem of the laptop is vastly better than the cell phone. The cell phone's processor is like a race car in city traffic; it can barely get started before it has to stop and wait for something."
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2etedt | what's happening in my head when sound gets drowned out while falling asleep and then a minor disturbance "opens" up my ears? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2etedt/eli5_whats_happening_in_my_head_when_sound_gets/ | {
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"I think your mind slowly blocks out all common noise perceived as safe, and you wake when something unusual is heard",
"Your brain differentiates between expected and unexpected noises. So the hum from the fridge or the music you left on is expected, but broken glass or some other noise is unexpected and your brain wakes you up.",
"No expert but I've read about this before. As your body goes through the 4 stages of sleep (there used to be 5 but two stages were combined recently), you become less aware of your surroundings. The first three stages are part of the NREM sleep (non- rapid eye movement), while the last stage is part of the REM sleep.\n\nNormally, your brain produces fast 'beta' waves, but as you're falling asleep, these waves become 'alpha' waves that are much slower. During this period you can feel strange and vivid sensations. This is when you might experience the feeling of falling, for example. I believe that this particular feeling stems from your organ of balance receiving less/no stimuli.\n\nThen stage 1 begins, during which the brain produces theta waves. These are extremely slow. Stage 1 lasts for about 10 minutes.\n\nStage 2 takes ~20 minutes while your brain has bursts of brain wave activity. These bursts are called 'sleep spindles'.\n\nStage three involves super slow 'delta' waves. During this stage your body is the least responsive of all stages. This is because your senses are very weak in this stage.\n\nThe last stage is the REM stage. This stage involves high brain activity but low muscle activity. This is when dreaming might occur.\n\nThen you wake up. Gotta go now so maybe someone else can further clarify.\n\n**Tl;dr:** A decrease in sensory stimuly weakens your senses. I believe that your hearing is least affected by this.\n\nEdit: alpha < > beta waves",
"What people seem to be saying about unexpected noises is probably a more accurate answer to your question, but I remember learning once that, in terms of words (as opposed to sounds), every word has a \"threshold\" for being noticed. You hear everything within earshot, but your mind filters out sounds that it thinks are unnecessary/irrelevant to the task at hand. This is what happens when you \"tune out\" what people are saying around you. Depending on the threshold of a word, some words get through the filter more easily. It's different for every person, but some examples of low-threshold words are \"fire,\" your own name, or other high risk/high importance words. That means that if you're tuning out everything around you, but someone shouts \"fire,\" then it is much more likely for you to hear it than if someone said \"dog\" (unless dogs are particularly important to you for whatever reason). This effect likely continues during sleep, because if someone is sleeping, they'll wake up faster if you say their name than if you just say normal words. (Fun fact: it is [supposedly] impossible to fall asleep when someone is saying your name repeatedly.)\n\nNot sure if that answered your question at all."
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7w1dua | why is e85 85% ethanol? | What makes that ratio so special? Why not a 50/50 ethanol blend? In fact, why don't they just sell pure ethanol and remove the reliance on petroleum all together? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/7w1dua/eli5_why_is_e85_85_ethanol/ | {
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" > What makes that ratio so special?\n\nIt is about as much as every passenger vehicles can take without damaging the engine.\n\n > In fact, why don't they just sell pure ethanol and remove the reliance on petroleum all together?\n\nIn the winter you wouldn't be able to start your car. There are no passenger vehicles designed to take 100% ethanol and the utility of a fuel consumers can't use is pretty low. ",
"E85 has between 51 and 83% ethanol, by law (in the U.S.). Outside of the US it has 85%, and you can get 100% ethanol in some places too, mostly in warm areas.\n\nYou have to mix it because it won't ignite in cold weather without some gasoline - the exact mix of ethanol and gas is often changed depending on where you are (the weather!).",
"Many reasons:\n\n* The higher the ethanol content, the harder the car is to start in the winter.\n\n* Ethanol makes the engine run hotter, which decreases engine life. 85% is a reasonable compromize.\n\n* Ethanol is problematic, in that it dissolves gaskets.\n\n* Ethanol also dissolves oil residue gunk in places where it isn't a problem and deposits it in places where it can be a problem. I lost a petrol engine to that (they also mix some ethanol into the petrol in Sweded), as the oil ducts clogged up and the top seized. I've heard from mechanic friends that this is starting to become a common problem.\n\n* Ethanol is extremely flammable. Petrol, while it burns spectacularly when ignited, is pretty hard to ignite, as it is picky about air/fuel mixture. Not so with ethanol. Ethanol wants nothing more than to go fireball, and will do so even from a tiny spark with a much wider range of air/fuel mixtures. Petrol tames it a bit. This, by the way, is why you can lock the trigger on the handle of a petrol or diesel pump, but not an ethanol pump. If you let go of the handle, static electricity might build up and produce a spark.\n\n* 100% ethanol would be possible to dilute with water and drink, providing a cheap and uncontrolled source of alcohol. Ethanol is the type of alcohol we drink."
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cg6jsu | why are nitrites toxic to tank fish, but nitrates are okay? | I understand my ammonia is toxic to fish, ammonia is toxic to a lot of living things, but what makes nitrite and nitrate so different? The only thing separating them is one oxygen atom. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/cg6jsu/eli5_why_are_nitrites_toxic_to_tank_fish_but/ | {
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"That one oxygen atom changes the shape, structure, and function.\n\nFor example Nitrates are used in many fertilizers and explosives. Nitrites are used in food preservation.\n\nNitrates form strong acids and nitrates form weaker acids.\n\nThat one extra oxygen atom in Nitrates makes a huge difference.",
"Kinda of an add on to [Fourtires3rims](_URL_0_):\n\nCO2 is not toxic but CO is toxic. Though there is only one oxygen missing. Well that oxygen changes the shape of the compound and/or its behavior.\n\nSCN is not toxic but CN is why because of the shape. Its shape allows to bond to protein (forgot, sorry) in ETC and thus does not allow your cell to use O2.\n\nThe same applies to NO2 and NO3 also another thing to note is that the charge on NO2 is 2- and NO3 is 3- and this charge difference changes what each of anions bond to."
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2s4ml7 | why is cancer the most common disease associated with dna mutations? | Is such a large part of DNA devoted to guiding cell reproduction that mutations always seem to lead to cancer? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2s4ml7/eli5why_is_cancer_the_most_common_disease/ | {
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"Of all the things that mutations cause (that is, mutations that happen *after* a person has been born), most of them probably just end up with the mutated DNA getting repaired or removed, or the cell that contains it being destroyed through programmed cell death. Cancer is the result of a mutation that removes the cell's ability to repair or quarantine mutations. It isn't that so much of DNA is devoted to reproduction that any one mutation is likely to damage that section of the DNA. It's that, of all the mutations that happen, the ones that can survive and reproduce are necessarily the ones that alter the normal reproduction/cell death processes (and these are the mutations that cause cancer.)",
"Other mutations exist, but one cell having some odd mutation doesn't do much. Mutations that lead to uncontrolled cell division cause that one cell to become exponentially more cells. ",
"So, with cancer, what is actually happening is a few things.\n\nFirst of all its not just one mutation. Your body mutates constantly, DNA is always messed up, and even then your RNA gets spliced up and you are making faulty proteins all the time. Mutation is actually how things evolve partly.\n\nThe concept with cancer is actually different than just mutation.\n\nThink of a car. If you cut the gas, well it won't move. Sometimes DNA will mutate and your body will find it and won't make it duplicate or be transcribed during transcription.\n\nNow DNA also can actually not be picked up by \"scanners\" when it mutates sometimes. We can call this cutting the breaks. So during transcription lots of crap happens that's not supposed to, and so we just let it go inside the cell and push everything that has been made out of the nucleus to get eaten up by lysosomses (cell stomachs).\n\nNow normally for actually cancer to happen, we need about 5 breaks cut and 10 gas pedals broken. It takes a lot of DNA fuckup to actually cause cancer.\n\nAnd if it does happen, we have this awesome enzyme called p53, which Is actually one GIGANTIC and I mean FUCKING HUGE protein made to just deal with cancer. An about 5000 different enzymes to detect it and stop it.\n\nCells also realize there is cancerous cells and go about trying to kill it, but then if we cut another 5 break lines and another 4 gas pedals in that cancerous cell, it won't tell other cells its cancerous.\n\nAfter that theres a tint threshold were the cell will try to kill itself, but one more break line cut, and that's it.\n\nIts pretty hard for this process to occur. But realize mutations happen like a thousand times a minute, and the \"gas pedals\" and \"break lines\" of DNA replication, transcription, and translation, are happening all the time."
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dbk0mw | why are some drink powders white but then turn a bright/deep shade after adding water | I noticed this happens with a lot or drink mixes mostly red ones. I'm curious how that works. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/dbk0mw/eli5_why_are_some_drink_powders_white_but_then/ | {
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"Artificial food coloring is extremely concentrated. A couple of granules, hidden among the white granules that make up most of the drink mix, are all it takes."
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6de844 | how and why are books like the great gatsby and of mice and men chosen for reading in english classes? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/6de844/eli5_how_and_why_are_books_like_the_great_gatsby/ | {
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"Considered part of the canon of English literature (heavily read, written about, and esteemed) and are also both accessible, easy, and short compared to many classics.",
"*Finally, my degree is useful for something!*\n\nSo educators are usually really *bad* at explaining why you read the things you read for school. The core concept to grasp here is the *literary canon*: that is, the body of works that are the foundation of [Western] literature. They are the most historically and culturally significant pieces of literature being studied currently. But how do works get added to the canon?\n\nThe surface layer is that they get into the canon because old stuffy [usually white, usually male] scholars *want* to study them, so they do, so it's expected that their students study them, so they do, so it's expected that to prepare for college you have to study them, so you do. It's not like a few Ivy League professors sat down in a dark, smokey room and discussed the future of the literary canon...but also it kind of is like that? Keep in mind, there are multiple \"sub-canons\". There is the American literature canon (featuring Anne Bradstreet, Thoreau, Emerson, Faulkner, Hemingway, Whitman, etc.); the British literature canon (Shakespeare, Geoffrey Chaucer, John Donne, Jane Austen, etc.), the poetry canon (Frost, Emerson, Whitman, Donne, Herbert, Shakespeare, etc.), the historical foundational canon (Homer, Virgil, *Beowulf*, *Gilgamesh*, etc.), the science fiction canon (Mary Shelley, Frank Herbert, Robert Heinlein, etc.). I know I'm throwing a lot of names at you; the point is that there is *the canon* and then there is \"I'm studying English poetry in the late 1800s, *these* are the people I should be reading\".\n\nWhich then **raises** the question, why do those scholars want to study those works? We have the benefit of hindsight, so *today* we might read Hemingway and [rightly] think he's boring and dry. But at the time his writing style was revolutionary. Before Hemingway, prose was all very *eloquent* and had propensity for verbosity. Hemingway wrote in a short, clean, *different* style. You may not like it, but he made it ok to *not* write in the old, stuffy way that everyone had been writing before him. That's not to say Hemingway was the first, or the best, but he was *good* and he was famous and he showed everyone that you could write in a different fashion. Suddenly everyone was writing in this new minimalist style, which in turn led to other changes in literature that allowed for the kinds of books we read today for fun. Without Hemingway, our literature today would look *very* different. Walt Whitman and Emily Dickinson did the same thing for poetry. Those are some very specific examples, but I hope they can demonstrate how authors can influence literature, and sometimes they're a part of the canon for those reasons.\n\nThe very old part of the canon is in there for much the same reason, but more in the sense of *inventing literature at all*. Homer's Odyssey is the foundational work for *so much* of western literature. Literally everything you've ever read, **ever**, was influenced by the Odyssey. And Epic of Gilgamesh is the oldest great work of literature - the oldest version of That Movie That Everyone Saw. It's the first ever example of real literature, which is kind of a big deal. Studying them can help you understand how storytelling evolved, by showing you how it started. I won't go into too much detail here about what, exactly, you would learn (narrative structure, framing devices...) because I don't need to give you an English lesson, eh? Suffice it to say, there's a lot there to unpack.\n\nSome works are a part of the canon because they're just easy to digest. F. Scott Fitzgerald is fairly easy to analyze and understand on a more abstract level, mostly because all of his symbolism is the same (that is, everything represents the \"unobtainable American Dream\"). It wouldn't do any good to say, \"Here kids, learn how to analyze literature by *analyzing the most difficult literature possible*\". Of course, unfortunately that's often *exactly* what English classes do. It's akin to saying, \"Here kids, let's learn how to do math. Shall we start with calculus? No? Trigonometry then...\" Which is unfortunate, because literature is awesome and there's some really cool stuff to learn...once you learn the tools you need to do it. But I digress.\n\nBut most of the canon boils down to be cultural icons of the time when they were published, or sometimes later when people rediscovered them. They can be both a window into the culture surrounding the person that wrote the works, why they wrote what they did, what symbolism they were using at the time, how they thought and viewed the world; and also a window into how that one piece of literature or author or movement changed the culture they were in, which trickled down to influence our own culture. They can also be ways to understand ourselves by analyzing our own reactions to what we're reading, and the literature in the canon often elicits strong reactions in its readers.\n\nNone of that is to say that the canon is perfect; far from it! I studied English and I hate huge chunks of the canon ([don't even get me started on *Catcher in the Rye*](_URL_0_)). But that's the idea of it: important literature that had a powerful influence on people and the times they were from, which encourages others to study that literature, which is itself a strong reaction that encourages others to study why the first people studied it, etc., so that it continues to have influence and continues to be important literature worth studying. TL;DR: The literary canon is literature that is \"worth studying\".\n\nEDIT: Important thing I totally missed. The literary canon is also supposed to be an introduction to your own national identity. When you so much as watch cartoons you'll be getting [references to cultural icons](_URL_2_). Seriously, as an adult go back and watch Animaniacs (it's on Netflix!) and see how many references you *didn't* get when you were a kid. When you read the American literary canon it's in part teaching you what it means to be an American. It helps build a unifying web of understanding, because when you make a joke about how painting a fence is \"fun\" and someone else laughs, you think *This guy also read Tom Sawyer* and you feel a connection with that person. Enough of those cultural connections help form the glue that is our national identity. It kind of sounds like indoctrination...and it kind of is. And that's not *bad* because it's teaching you about your country and how to be a citizen of that country, which is perfectly fine as long as it doesn't get out of control.\n\nEDIT: Hemingway has one m. I derped *so hard*. Thanks for the guys that caught it. EDIT: and Emerson, dammnit. I am a derp, sorry for the typos. Eventually I'll run out of names to misspell.\n\nEDIT: for the pedants: ~~begs~~ raises\n\nEDIT: Obligatory Thanks for the Gold, but [I think they misspelled Emmerson](_URL_3_). ^^/s\n\nBecause people have been asking: [This is my scifi reviews/essay blog](_URL_1_). The responses have really been really encouraging, so I'm going to try to revitalize it and get to posting there again. If you're into aquariums, [I also have a blog about aquariums](_URL_4_). I do most of my writing on Reddit, though - right here in ELI5!\n\nI have been convinced to reread *Catcher in the Rye* to see if age will give me a better perspective. I stand by my dislike of Hemingway, but if you enjoy him don't let me stop you.\n\n**TL;DR - Like the rest of this comment, the books you are assigned to read in class are probably worth reading for reasons that will be made clear if you read the rest of that book/this comment.**",
"They are easy to teach. \n\nOf Mice and Men is packed full of figurative language and writing tools (metaphors, similes, foreshadowing, imagery, idioms and personification), which is necessary for teaching English and writing. \n\nIt is relatively short so not unreasonable to expect students to be able to read it in full in a short period of time and not expensive to print, relatively speaking. \n\nThere are lots of classic and canon books out there, but they can be too long, or the symbolism is absent or too obscure & complex for high-school teaching. \n\nAlso I love John Steinbeck so don't mind adding that it is genuinely an enjoyable and unpretentious book to read as well. \n\n(I haven't read Gatsby so no idea on that one)",
"Most curriculum cover brit lit, or american lit, which explains certain titles of literature chosen from that time,but most always they choose from classics, specifically from what's called the \"western canon\", a selection thought to heavily shape western civilization.\n\n_URL_0_",
"They choose the books based of Historical/cultural significance and writing quality. Basically all the books you study should be chosen based on some important theme in them - of Mice and Men is about the depression, Gatsby is about the Roaring Twenties and To Kill a Mockingbird is about racism and the Great Depression. This can inform the students about important context (especially Mockingbird) and a 'real connection' often makes books more attractive to study. \n\nThe other reason is that these books are easy to analyse. They are full of symbolism, foreshadowing and the historical context. Books like Frankenstein might be a dry read but it is a goldmine for analysis, and the deeper themes present (social commentary, (possible) homosexuality) means you can go to town on them. It is far easier to study that (and will benefit your skills more) than to go for something more enjoyable and (often) newer - which are often more readable but less deep (or restrictively long). \n\nOf Mice and Men is a really easy text to do analysis in, it's short and full of foreshadowing. Gatsby also has foreshadowing, but also themes of wealth, inequality etc. And some books can be 'read into' easily - that Nick is gay is not specific in the text but many student pick that up and believe it, it gives chances to develop skills simpler books don't have. \n\nThese make then qualify for the studying 'cannon', books like Gatsby and Of Mice and Men are chosen a lot because of the wealth of secondary literature on them, making critical opinion easy to find. ",
"I have taught in South Central LA and I now teach in Urban Indonesia. I have yet to have one student not connect personally to Of Mice and Men. Whether they are in a gang or a billionaire (I've taught both) there is something in there for them. Part of literature and story-telling is that it unites us all. Good stories can transcend time and culture. The mythical Canon is usually made up of books that teachers believe do these things. ",
"First off, my credentials: B.A. in English from UC Santa Barbara, M.A. in Modern Literature from Queen Mary University of London.\n\nJohn Steinbeck and F. Scott Fitzgerald are canonical American authors. Period. Full stop. Why? They were best sellers. Why? Because they captured what is known as the \"zeitgeist\" or the 'spirit of the era,' to paraphrase. They also happened to be masters of the novel form. Don't believe me? Read \"East of Eden\" and \"Tender Is the Night.\" Disagree? Go ahead. Write something better. These men wrote what is known as \"the great American novel.\" Who will be next?\n\nYou?\n\nHer?\n\nMe? \n\nWho knows?\n\nBye.",
"They live in the sweet spot for the reading comprehension level in high school. Easy themes, short, secular,\n\nPlus they teach you valuable life lessons. Like wearing a glove full of vaseline to keep your hand soft for your fiance. ",
"Any combination of these:\n\n(a) They're considered classics because people still enjoy them (or find value in them) long after they were published;\n\n(b) They're considered edifying, in that typically they have a strong moral message;\n\n(c) They present a full smorgasbord of things that can be studied, such as strong narrative themes, characterisation, cultural properties, historical interest, and so on. \n\n",
"Books such as Gatsby and OMAM are chosen because they are arguably the most accurate representations of the literary philosophies of their respective time periods. Perhaps the very reason that English classes study books at all is to gain an understanding of the author and his/her perspective, but these so-called classic books give insight to the opinions and values of the masses at the time. For example, Gatsby was written by one of the prime modernist writers, F. Scott Fitzgerald, who was able to really capture the essence of early 20th century America in the novel. Because of this, students can go back and study Gatsby to gain some kind of understanding of what life may have been like during that era and possibly garner some new perspective that can be applied to their own belief systems. ",
"Ooh ooh I got one more for this one. How are graphic stories like \"The Lottery\" allowed for children to read in English/ELA classes? I read that and the lesson was \"somethings were deemed too inappropriate\" and that was it. Had to write a book report on a stoning which could still be very possible just because of the wow factor of the story at the time of its original release, nothing of value was learned from it.",
"When I took an Access to University course I learned so much. We studied a variety of subjects; history, psychology, English literature were my main three; and I found that they all went hand in hand.\n\nWe studied One Flew Over the Cuckoos Nest by Ken Kesey, Trumpet by Jackie Kay, the poetry of Maya Angelou, , A Passageway to India and The God of Small Things by Arundhati Roy. We did some Shakespeare and short stories by Roahl Dahl, The Vendetta by Guy de Maupassant, The Veldt by Ray Bradbury, Town and Country Lovers by Nadine Gordimer and poetry by the Brontë sisters.\n\nThis literature is like a snapshot of the time in which it is written. Not only do you learn about the style of writing a great deal, you also pick up knowledge of important events and themes that made me feel more well rounded as an adult. \n\nI wasn't a feminist until I was introduced to the idea through history and literature. I learned about the Suffragettes in History, read literature that illustrated examples of prejudice in action in English Lit, and studied the psychology of discrimination and prejudice in Psychology. \n\nThey expanded my knowledge of Apartheid, mental health before the 60s and how this tied in to women and the idea that both the mentally ill and women were discriminated against and locked away. \n\nI learned about Slavery and Racism, and how that tied in to feminism. And society and class, again showing the oppression of minorities and looking really at the different ways we identify ourselves and others, and how that can make us feel, both good and bad.\n\nAs I learned I realised that not only was this studying helping prepare me to learn at a higher level, I was becoming more well rounded as a person. Knowledge was not the only thing imparted, it shaped me and the way I thought. I learned more about myself on that course than in the whole of my life before it, it showed me ideas that I had never considered before, taught me how to think critically and how to express myself. \n\nWhen I looked back at the literature I studied in high school, I had a much deeper understanding of why I was taught these things. Literature was a vehicle for so much more than words on a page. It helped me to see why I studied, who I was inside, what my values were, what direction I wanted my life to go in and broadened my horizons in life. I wanted to know more about everything. \n\nI've not done my degree yet and it's been a while since I studied so forgive me if I am not entirely clear or have gotten any authors or titles wrong.",
"There are two reasons we read these books: \n\n1. The books are part of a group of well-respected books called \"the canon.\" These are books that over the years scholars have studied again and again until they became \"classic.\"\n\n2. Out of all the books in the canon, some are easier to teach because they are more obvious in their use of literary devices (tools writers use to make their points). The Great Gatsby, for example, uses metaphors and symbolism all over the place. They're easy to point out and kids get a quick win when they recognize them. \n\nMost high school reading fulfills both of these criteria. Occasionally you'll see teachers pick books that aren't classic but have a literary device they want to teach, or you'll see books from the canon that are harder to teach but important to learn (some Shakespeare). But you'll seldom see some of the denser or more ambiguous books in the canon: I've yet to see a high school teacher try to teach Ulysses. \n\nEdit: TIL that plenty of high schools were way cooler than my kinda crappy backwater public school and taught Joyce's Ulysses. Color me jealous. ",
"Because books like these contain many levels and layers of meaning to reflect upon. Some of those layers will be noticed by teenagers, perhaps some mostly by adults, and perhaps even some only to senior citizens. As a reader grows, evolves, and gains life experience there are new ways to look at them in addition to the teenage ways. This is why \"old, stuffy, white, or male\" readers might consider them worth rereading in the first place. If there was something about the books that continued to resonate with those readers, then that value will be available for the following generations of readers. In short, the books of the 1920's that did NOT resonate with teenage readers of subsequent generations aren't being taught in English classes. Likewise, books written in 2017 that do not resonate with subsequent generations will NOT be taught in English classes in the beginning of the 22nd century (regardless of the race or gender of the author.) It takes a long time to realize this.",
"Classics in American literature are chosen because the story or the hero reflects an important part of U.S. culture, ideals, or history.",
"Haha! Finally MY degree is useful here. I am a special education teacher and teach middle school high functioning autism. I also happen to teach for a cooperative, mrsningy (edit: most of my) students come from all around the area, covering multiple school districts each with their own set of expectations for student growth. I'm basically told each year \"figure something out\".\n\nNow this would be golden for most teachers who hate teaching from a required script but since I deal with students who hate school by the time they get to me, it can get tough. I'm also a veteran teacher so my admins just figure I know what I'm doing (sometimes I do sometimes I don't). I'm given a budget each year and expected to field an entire curriculum from that.\n\nAbout 4 year ago I decided that having them read science fiction and fantasy books is over. They prefer that type of story because it's more fun to read, but I hate Harry Potter and the hunger games by now, so I decided to find books that would challenge them. We now read classics iny classroom like \"Of Mice and Men\" and 'Huck Finn\", books that have far deeper meaning than anything they would ever read on their own, and books that even most middle school teachers avoid. \n\nSo for my experience, we read those books because I want them to. \n\nEdit: We read Percy Jackson each year because I can tie in Greek history and they get a kick out of that. We do read plenty of books they enjoy but I HAVE to expose them to historical literature or \"classics\" such as The Outsiders which most may not consider a classic yet. Most of my students come to me because their home schools have given up on them and can't figure out how to teach them. I have a specialized classroom designed for their needs and while it is a relaxing place I force them to challenge themselves and at times the work is far tougher than in their home school because I do have that easier environment to learn in. But they all come out better people because of it. If I don't they won't be prepared for high school and I have yet to have a student not finish a book and love it after six years in this group. Yes it's hard and yes they fight at first but once we see in there I see the light in their eyes and I know I have them hooked.",
"As an English teacher - they're the only books the school has copies of so we get to read them. Specially true with Shakespeare. O I love him but I don't love Romeo and Juliet or Midsummer's Night Dream. I'd love to read a winter's tale or richard III. Or even a play by a different author from the same time like The Roaring Girl which is about a girl who dresses like a man and had sword fights. But the schools can't afford new books.",
"As an English Lit grad, high school teacher and college prof, I love this post and all the discussion, passion and debate.\n\nHarold Bloom offers us his version of a western canon of 26 works and explains why they should be part of the canon.\n_URL_1_\n\nAlthough Bloom does not ELI5, it does offer us a succinct list. But it also points out that anyone can make their own canon. Although Bloom is not just anyone in scholarly circles.\nHe also makes explicit that his is a \"Western\" canon. Other canons exist, either by geography or by theme, style, gender, period, language etc. The number of canons could be endless.\n\nAn author that tops my canon is Milan Kundera, and my favourite is \"Immortality\".\nb p nichol is my favourite poet. So playful and free!\nNot sure if these make my canon, but I love reading Vonnegut, Hunter S Thompson, Chuck Palahniuk. \nI couldn't wait to share each new Harry Potter novel with my son and loved how so many of my students got turned on to reading by J K Rowling.\nWas about to submit, but can't without adding Arthur C Clarke, Robert Heinlein and even the Ender's Game series although I choke a little when I think about its author's religious and moral beliefs.\n\nKeep reading and enjoying literature!\nWho is in your canon or canons?\n\nedit: replaced book cover with blurry angel butt with alternative edition\n \n _URL_0_ ",
"So my wife is an English teacher and she is going through the process to pick out her books for next school year right now. The teachers are limited by a number of factors. \n\nTo start, they are limited by school funding and student fees. My wife's school won't let her spend more than $12 worth of books per student, she since teaches in a poor rural Ohio school district. Because of this limit, she can only spend $3-4 per book. That limits her to only the mass market books. In truth, she wants to branch out to do different, more modern works, but just buying one would blow her entire budget and leave her without enough materials to stretch out through the entire school year. \n\nSecond, she has to choose books that fit into her student reading levels. They use lexile ranges, which are a way to measure reading levels. Lexile ranges don't necessarily correlate with grade level. She teaches 9th and 10th grades and she has students reading between 2nd and 12th grade reading levels. How does she choose novels that fit for all of them? She can't. \n\nThird, she has to deal with the administrators. Some of the administrators are very opinionated about what books are taught. \"To Kill A Mocking fits with what the 10th graders are learning in social studies, so I want to you teach that to your sophomores.\" The administrators are also much more difficult to convince the value of some of these more modern and innovative books she wants to teach. \n\nSo between all of these factors, my wife only has a handful of books to choose from. So you know what she ends up having to order? The old standards. In some cases, she doesn't mind, but she is definitely annoyed by how little room choice she has in the selections. ",
"I remember having this same thought in school while reading one of the many short storya out of the big litarature text books. Always being asked to reflectand find meaning in the stories. I always missed the big obvious morals and made up my own whimsicle reflection.",
"here is an alternate view of why\n\nBecause some pretentious people in the past, that invented fictitious reasons why the books were awesome, told younger people that these books were awesome...and being young some of them believed the pretentious people knew wtf they were talking about. They in turn got into positions of authority and regurgitated the same crap to more future young people. \n\nNow we and our children and our children's children are stuck reading the same boring books because some a-hole 60+ years ago thought they manufactured some hidden meaning or lesson from something that was just a book.\n\nthis is the same principle behind rich people pretending that caviar and pâté actually taste good....when in reality they both taste like crap",
"The fact that they are short is more important than it should be. There are other reasons, but short makes books a lot easier to teach. ",
"Books like 1984 or similar things are read in school usually to help teach critical thinking and logic.",
"The \"great books\" don't always cover deep topics but also are considered benchmarks in the use of language. My favorite example is Moby Dick. As a book it's frankly boring, but open it to any random page and read any random paragraph and it's just perfect. Somehow Melville wrote an 800+ page epic in which every piece of it reads like poetry. Ditto Shakespeare.\n",
"It's important that kids know what great literature is, even if it's \"forced\" on them. They may not like it when reading it at first but at least they get to know that there is more to literature than Harry Potter and the likes.\n\nIt's like when I was younger I was exposed to all that great music from my parents all the time. Even if I didn't like it and preferred my own modern music at the time, it gave me a sense of what music could be. As I got older, I learned to appreciate great classic music and different genres which I might not have developed if it wasn't for my exposure to it when I was younger.",
"I'm a high school teacher. I teach those books because I like them. Many people who are extremely uninformed about education standards will tell you that I have to follow some formula or series of worksheets, but in reality the English standards can be easily applied to any book as long as they aren't commercial fiction. I enjoyed those books, so I get to force students to read things I like. I'm definitely not about to spend 40 weeks a year trudging through books I hate. It's hard enough to get students to do and enjoy reading, not liking the book yourself just makes it harder. ",
"I don't know, All I remember is that in secondary 5 (Quebec french school) I had to read \"Des souris et des hommes\" in french class and \"Les miserâb\" in english litterature at the same time... a whole semester hearing \"Jean Valjean\" in english when 100% of the students were native french speakers. Teachers do whatever they want I think.",
"When teachers see those books they think: -\n\nOh, what a cute little book. Just what I always wanted. My own little book. I will name him George, and I will hug him and pet him and squeeze him and pat him and pet him and rub him and caress him and...",
"what I never understood is why we were forced to read Shakespeare. I had so many teachers who hated it. When you're 14 years old in ninth grade, even the spark notes version doesn't really make sense. What they should really do is strength your ability to write, so you don't end up like all the college kids in my classes who still didn't know how to use a semicolon\n\nthey focused way way too much on expository writing. They should be teaching research based more, learning how to get the facts. Technical is good too, and creative writing is a really good way to expand your mind.\n\nour public education system in America is lacking, a great example is how it is heavily based too much in the past. The world changes and so should the way we teach. The fact that not a single class I ever took in public school history went beyond the Cold War means they really don't give a shit. How are we supposed to focus on changing the future if you don't teach your kids what happened in the past 30 years, but rather what happened 600 years ago. I had three classes on the French revolution but never once learned about the Vietnam war or first or second Gulf Wars\n\nPublic education in the USA in 99% garbage. You want our kids to be successful, so you teach them nothing and then blame them for incompetence. Fuck the baby boomer generation",
"Dale Carnegie once said that when he goes fishing, he doesnt use strawberries and cream as bait, but worms. Now he can never understand what fish find so appealing about worms, but then again, he doesnt have to.\n\nSo to answer your question, schools are fishing (teaching) with strawberries and cream (literary classics) and wondering why the fish (students) arent biting (reading).\n\nIm sure the denizens of this subreddit will downvote me to death, which is fine, but remember, teaching is about relating to the student more than getting the student to relate to you. ",
"Ill pitch in because Im an English teacher. Usually the books we read in class are determined by what we have available in storage. There isn't a big annual budget for new books so we work with what we have. Shitty answer but true. I cant ask my students to buy their own books so short of the cost coming out of my pocket, my hands are tied.",
"Possibly because they are great books, they challange students and deal with important political and moral issues that we often still deal with today. Like acceptance and stuff like that. That's my opinion anyways. Could be wrong. :)",
"As a professional writer, subjecting students to the classics before they have a baseline enjoyment of the act of reading fiction really chafes me. I think a LOT of young readers are permanently turned off of prose fiction because of stuffy, obtuse, irrelevant shit they were forced to read in high school.",
"I'm probably too late for this shindig, but there's an important component I see many people missing, and this is, in my view, the most important reason we read books like Huck Finn, The Great Gatsby, and Pride and Prejudice.\n\nYes, part of the answer here is the 'canon', i.e. there's a (possibly arbitrary) group of central texts chosen by old white dudes with Oedipus complexes. Look at other comments for answers about the canon.\n\nNow, I have a problem with the 'canon' answer because it's overly simplified, and is often used as a false comfort. 'The Canon' is the answer people want to hear if they don't understand why they're being made to read *The Great Gatsby*. That is, if you're just bored by *The Great Gatsby*, it's comforting to say, \"Well, some boring old white dudes arbitrarily decided I should read this when really it's just boring drivel that has no relevance to modern life and that's Fitzgerald's fault, not mine, let's move on to Harry Potter. Fuck the canon, it's racist.\" (The canon is, indeed, pretty racist, but let's move on)\n\n**Something I don't see people talking about, however, is literary tradition, which I see as the more significant reason to read writers like Fitzgerald and Steinbeck.**\n\nTo explain: writers read each other. Whom writers read and whom writers like will impact their own work. Toni Morrison's *Beloved* is illuminated if, afterwards, you read Faulkner. Morrison wrote a Ph.D. on Faulkner for cryin' out loud. That doesn't mean you can't read *Beloved* without *As I Lay Dying*; it simply means Beloved will be a different, and more interesting book if you do. You can't fully appreciate J.G. Ballard unless you also understand Joseph Conrad. J.G. Ballard is basically using the exact same metaphors as Conrad, just updated and less racist. He's admitted as such. If you read Virginia Woolf before you read Ursula K. Le Guin, you'll be amazed by the connections you'll make. The texts dance with each other. It doesn't matter that Le Guin writes Science Fiction and Woolf writes in the mode of Modernism--Le Guin has been heavily influenced by Woolf, and reading the two together is very enlightening.\n\nAnd then come the two giants of them all: Shakespeare and The Bible. Look, you can read literature without having read any Shakespeare or any of the Bible, but that doesn't mean you'll be erasing the ginormous impact these works have had on literature. In the most fundamental ways, the language of The Bible has seeped into the entire umbrella of English literature. Even if you don't know it as a writer, you're either adopting the ways The Bible uses words, or rebelling against it. No matter what, you're always responding to it. It doesn't even need to be purposeful on your part.\n\nSo, yes, there's an aspect of 'the canon', but the canon wasn't just chosen by stuffy old white men. It was also chosen by writers, and a writer worth their salt will have read from the canon, and will know what interests them, and what they think is missing. To track this progression can give us insight into the way dialogues in our culture develop. It isn't arbitrary that Toni Morrison is following in Faulkner's footsteps, and it certainly isn't because some old white dudes told her to and that was that.\n\nPart of the issue is that high school students don't necessarily have the perspective available to approach some of these texts, and it's often in high school where these texts are read. For example, what does an expedition down the misty Congo river have to offer to someone going into engineering, or politics, or environmental science? I think the reason a book like Conrad's *Heart of Darkness* evades us is because books like it are often taught in the wrong way.\n\nHere are some ways to rethink some of the writers you didn't appreciate in high school:\n\n**Jane Austen** is the Lena Dunham of Gentry Era fiction. She's a ruthlessly observational genius filled with radical ideas about women and romance. She's totally brutal, too. A good high school teacher will guide you to see how fucking hilarious Jane Austen is. She's a bitch, and she knows it, and she doesn't care. For example, There's a whole section in Pride and Prejudice where Mr. Bingley attempts to justify his bad handwriting by arguing that he's just really smart and thinks too quickly. Austen writes this dialogue so perfectly, so cunningly that, in the end, her character Elizabeth totally brings Mr. Bingley down to size. We've all met people like Mr. Bingley, is the thing. However, if you don't understand how Austen's humor works, it could come off as simply gentle banter. Furthermore, her legacy is still felt today.\n\n**Joseph Conrad** fathered (or at least perfected) a certain kind of thinking. His works combine intense societal critiques through the power of individual consciousness. Basically, he's one of the original \"the personal is the political\". Even if you don't like *Heart of Darkness*, you're never escaping its impact (which has been followed by many great socialist thinkers btw).\n\n**Mark Twain** basically created American literature. It was mostly very puritan before he came along to satirize the moralization and piety of American literature coming before him. There's no way in hell that some stuffy white men facilitated this. American writers like John Steinbeck, Faulkner, Don Delillo and I'd even argue Bret Easton Ellis have all learned lessons from Mark Twain. His lasting impression isn't because a couple of Harvard deans standing around in a room smoking cigars suddenly decided he's interesting. It's because he's a great writer, and writers after him have either copied him or tried to repurpose his techniques.\n\n **Shakespeare** literally somehow captured and predicted every single literary movement that has happened and probably will ever happen. If you feel a certain way, Shakespeare has written about it. If you don't like Shakespeare, it isn't because you're right. It's because you didn't have a good professor to guide you. I know that may make you feel insecure. How could one dude be so amazing? Well, he was, and you need to deal with it. Shakespeare is the only writer I can say this about with absolute confidence. With the proper introduction, he's one of the most fascinating writers (if not *the* most). But he absolutely needs a guide.\n\nThis goes into the very purpose of literature, which is this: if we want political progress, scientific progress, mathematical progress, we need to know how to redefine our own personal vocabularies. All great writers have, in some way or another, reinvigorated or dismantled the old cliches of their times to document the cultural, intellectual, and psychic changes they observed. Writers give us language we can use to explore our experiences, and reading in terms of a tradition helps us see how languages and conversations develop.\n\nIf you want to dismantle the cliches of conservative America, or SJW liberals, or Orthodox Christians, it helps tremendously to see how geniuses have done so in their own contexts.",
"I have a BA and MA in English Lit, and I am currently studying to be a high school English teacher. I have been asking myself the same question as I try to figure out what I will be able, or required, to teach.\nI think there are three aspects to your question. I will address each briefly, sharing what I have learned so far in my own research. \n\n1. Why are books like Of Mice and Men and the Great Gatsby taught instead of other kinds of easier, more interesting books, like science fiction, fantasy, young adult fiction, or popular novels like mysteries or thrillers? This question is relatively easy to answer-literary merit and textual complexity. In ELI5 terms, the books are great but hard. Many posts have already addressed the issue of “greatness” (literary merit), and the issue of “difficulty” (textual complexity) has also been mentioned, and I don't really have anything to add. If you are interested in learning more about this aspect of your question, I recommend reading the [Common Core Standards for English Language Arts](_URL_2_), which also provides a list of “sample” books for high school English classes.\n\n2. Why are books like Of Mice and Men and The Great Gatsby commonly chosen, instead of other books that are just as great, and just as hard? This question is harder to answer, and, in my opinion, more interesting. It seems that there are a small number of books and writers commonly taught across the country-Steinbeck, Fitzgerald, Angelou, etc. Yet there are hundreds of other writers and thousands (tens of thousands) of other books that are just as great, and just as hard. California alone has identified [421 “recommended” books](_URL_0_.) that can be taught in CA high school English classes, many of which I have never heard of. I think a lot of this has to do with force of habit-one generation decides these books should be taught, so the next generation believes that these are the books that should be taught, which leads to them teaching these books to the third generation, and so on. The novelist Francine Prose makes this argument in her essay [I Know Why the Caged Bird Can’t Read](_URL_1_)(She also argues that many commonly-taught books, like Of Mice and Men and To Kill a Mockingbird, are not that great and should not be taught.).\n\n3. The \"how\" part of your question-what is the process by which books like Of Mice and Men and The Great Gatsby are chosen for high school English classes? Many posts have talked about this already. I would only add that it seems many schools use “anthologies,” (textbooks that contain poems, short stories, plays, and novels, as well as questions and assignments), and that teachers have to teach the books in the anthologies. Of course, this raises the question of why publishers include certain books in the anthologies, and why schools choose certain anthologies. These are also interesting questions. Unfortunately, I have little to share here. I will, however, predict that high schools will more and more end up teaching the same small number of writers and books because of the Common Core educational standards. The Common Core standards identify a small number of “sample” books that meet the standards, and I predict publishers will end up including these books in their anthologies, with the result that these books will end up being taught in public schools everywhere. For all I know, this is happening already. (It is also possible publishers will try to be different by choosing different books. I hope this turns out to be the case.) \nEdited for formatting.",
"Easiest TLDR I can think of for this:\n\nYou know how stories always reference other stories? Like when the Simpsons references Rocky 5 or something?\n\n\"The Canon\" in any kind of literature are the books that all the other books reference back to. So \"The Great Gatsby\" is important beacuse almost every other book about \"the american dream\" that was made afterwards contains some kind of allusion back to that book. Shakespeare matters because later plays all referenced back to Shakespeare. Frankenstein matters because every story afterwards about \"science gone mad\" references back to it. Every fantasy novel references back to \"Lord of the Rings\", which itself references back to \"Beowulf\" and similar legends. \n\nIt's not universal or automatic, and there's always debate about which ones count, but usually books are chosen because of their importance on that level. ",
"Follow up question: How do we benefit from Shakespeare? The language within his work is a fantasy language based of a dialect of English that's been dead for more than 2 centuries. On top of that nothing in any of the stories I read taught me anything along the lines of morals or even proper story structure. They were just a giant mess of random problems and solutions that seemed extremely pointless.\n\nNot to mention characters lacked any depth whatsoever and their intent was usually apparent within their first scene.",
"Of course the answers from English teachers are multiple paragraphs long that could be summed up in just a few sentences. ",
"Look up \"literary merit.\" Certain works of literature express literary merit usually because a number of scholars can identify profound significance (ie beyond being a good story). Whether it actually exists is another matter.\n\nOf course, this assumes a five year old can use Google.",
"One factor that I haven't seen mentioned (though hinted at): a book that is public domain usually costs ten times less than a book that is still under copyright.\n\nThis means that there is also a substantial *practical* reason why many schools will restrict their classroom supplies to older works.\n\n(There is also perhaps an additional angle that it is presumably more difficult for a work to enter the canon when it is still under copyright because people are not so free to share it or reimagine it or rework it or recast it. Whenever its nature of being private-property conflicts with its nature of being culture, its nature as private-property often has legal priority.)",
"And when will we start having useful ones chosen that will help with adulting?",
"We had to read Fahrenheit 451 in eighth grade (I was 13) and it seriously changed a lot of my opinions and beliefs. I got super involved in class while we were reading it. Then I read The Great Gatsby when I was 15, which I also fell in love with. These classes helped me appreciate books besides teen fiction. So I'm pretty glad I was forced to read these classics. ",
"Both are great books. Personally, I enjoyed reading them in my English classes. We also read To Kill A Mocking Bird, Lord of The Flies, The Odyssey, and Huck Finn which I think are great books as well. The way I see it, reading these books not only challenge students but also exposes them to different genres of story telling aside from Harry Potter, Hunger Games, etc.",
"Circling the wagons and protecting the narrative. \n\nLike if you had engineers teach English they'd cover comic books and manga. ",
"I'm super late to this, but can someone tell me what are the reading requirements in American high schools? \n\nI know it differs according to the teacher or school, but I'd just like to get some examples of reading lists. I'm from Europe and every year we got a list of books we were required to read. It was a mix of national literature classics and world literature classics. I'm wondering how similar are our lists to American and other lists around the world."
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"https://rhynoreviews.wordpress.com/",
"https://www.youtube.com/watch?v=6jDcWAWRRHo",
"http://i.imgur.com/gFLVgp4.png",
"https://amateurproaquarist.wordpress.com/"
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"http://www.corestandards.org/ELA-Literacy/"
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r1ka1 | sarcasm and irony | I have a hard time discerning those two. Aren't they basically the same? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/r1ka1/eli5_sarcasm_and_irony/ | {
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"Irony: \nThe use of words to convey a meaning that is the opposite of its literal meaning or an outcome of events contrary to what was, or might have been, expected.\n\nSarcasm: A sharply ironical taunt; sneering or cutting remark\n\nSo sarcasm is an ironical remark used to taunt someone.\n\n[_URL_1_](_URL_0_)",
"Thanks everyone! It was very helpful!"
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20rx5r | Why are there tigers in Primorye and historically throughout Siberia, but none in the similar ecosystem of Alaska? | Was there something that prevented the migration of Siberian tigers across the land bridge between Asia and the New World? | askscience | http://www.reddit.com/r/askscience/comments/20rx5r/why_are_there_tigers_in_primorye_and_historically/ | {
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"There were a number of large cats that formerly inhabited North America, such as the American Lion: _URL_2_ And the Saber-toothed cat: _URL_1_\n\nThe only species to survive in North America into modern times is the Cougar. _URL_0_"
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194x8d | What does it mean for a substance to have 0 viscosity? | To my understandsing, when a substance enters a superfluid state, it has a viscosity of 0. To achieve superfluidity a substance (i.e helium) must be pressurized and cooled to fractions of a degree above absolute zero. What properties would one such substance have? | askscience | http://www.reddit.com/r/askscience/comments/194x8d/what_does_it_mean_for_a_substance_to_have_0/ | {
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"It's been a few years since I last did matter at low temp, but IIRC there are a few things that characterise such a state:\n\n - Film flow: superfluids are capable of climbing out of open beakers, even against gravity. Here is a cool [video](_URL_2_)\n\n - Superleaks: Superfluids can leak through incredibly small holes which normal viscous liquids would be unable to do. So one example would be a narrow tube packed with loads of cotton wool.\n\n - Fountain effect: [video](_URL_1_) and [link](_URL_0_) will explain better than me\n\n - Also quantised vortices but I don't know enough about them, maybe someone else can fill in",
"A velocity gradient of the fluid will have zero associated shear stress. (i.e the only property of the fluid that will \"resist flow\" will be the mass/density of the fluid itself)"
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4vlhvk | Is there an infinite number of wavelengths on the EM spectrum between 2 wavelengths? | If you take 100nm and 101nm wavelengths, is there an infinite number of wavelengths on the EM spectrum between 2 wavelengths or is this number restricted by Plank's Constant? And if there is an infinite or finite number of wavelengths emitted within the visible spectrum, does black body radiation from the sun emit that finite or infinite number of wavelengths or less than the theoretical limit? | askscience | https://www.reddit.com/r/askscience/comments/4vlhvk/is_there_an_infinite_number_of_wavelengths_on_the/ | {
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"No, it's infinite. All wavelengths are allowed.\n\nPlanck's constant cannot do that, and you can deduce that without knowing the physics. The theory of photons is free quantum electrodynamics, which has only two dimensionful constants: c and hbar, respectively from relativity and QM. c has units of length/time, hbar has units mass×length^(2)/time. If you had some kind of discretization of wavelength, which has ofc units of length, the step should be a pure number times a length obtained by combination of powers of c and hbar. But as you can see, there is no way to build a length multiplying powers of c and hbar.",
"Here is another argument for why any wavelength is allowed. Consider 1 inertial reference frame where you have a photon of frequency w. Since all inertial reference frames are valid, and the photon travels at c in all frames, if you go to another frame, the frequency of the photon changes due to a doppler shift. If you choose a new target frequency w', there exists a reference frame where that photon has that frequency. Therefore there are no \"special\" values of frequency, since there are no \"special\" reference frames, and in fact, all photons, even ones with different energy, are identical."
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6rgvis | how come after only a couple days of not working out, i feel and look like i'm not in good shape anymore? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/6rgvis/eli5_how_come_after_only_a_couple_days_of_not/ | {
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"It takes a lot of energy to maintain muscle mass. If you aren't using it your body thinks it's better off \"eating\" it. Bodies are built for survival, not peak performance.",
"It's honestly a mental thing. If you think you look/feel good, then you will (if you're pretty healthy). I know that I feel like I'm in a funk when I don't work out for a few days. It's all in my head, though. ",
"Endorphins post workout can help boost your self-esteem and may help you feel better about your body image. Those effects can wear off after some time if you don't continue to work out. Relatively to how you felt before, you may not feel as great. ",
"Our body gets used to stretching it's muscles and having blood flow at an increased rate. After a couple of days of not working out we may feel out of shape because our body is craving exercise. We may also look slightly less bulky since we aren't pumping blood at an increased rate, but it is mostly all in our head. ",
"Its all in your head, trust me. Thats the mentality with working out is you feel you havs to keep pushing and you should always go to bed with sore arms/legs/chest or whatever you just trained, otherwise youll miss out.\n\nIf youre training for mass, youll find your muscles do take a fair while to deteriorate due to inactivity. Like up to 2 months IIRC. But your strength will decrease faster no doubt. Rest is healthy for gains but you cant do it too much or else your body will get too comfortable and soften up.\n\nConsequently thinking you look worse for missing a week or so is a mental state you enter due to feeling lazy and sluggish.\n\nTl:dr its all in your head."
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7j9st6 | how and why exactly does anxiety affect your whole body? (eg. digestive system, feeling cold, etc) | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/7j9st6/eli5_how_and_why_exactly_does_anxiety_affect_your/ | {
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"Stress causes your adrenal glands to release adrenaline which causes a wide range of physical symptoms. ",
"Anxiety evolved to deal with threats, so the body can respond accordingly. A lot of the physical symptoms are related to the hormones released to prepare your body to fight or flee. The reason you get digestive symptoms is because the hormones restrict blood flow to your digestive system, so there is more blood available for your muscles and other organs to use. Feeling cold is explained by blood vessels near your skin constricting to divert more blood to muscles and other important organs.",
"For anyone with anxiety problems I recommend this Ted Talks video, it’s very informative and might really help!: \n\n_URL_0_\n\n"
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2yh80p | Why was Portugal accepted into NATO? | Specifically, why the isolation for the fascist regime of Franco after the war, but not for the Estado Novo? | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/2yh80p/why_was_portugal_accepted_into_nato/ | {
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"While both regimes shared very similar outlooks (Corporatist, authoritarian, conservative, anti-communist states) both had significantly different reputations after the 2nd world war. Salazar was an incredibly well regarded statesman, who had a great dislike for Hitler and who stayed neutral during the war due to a strategic issue (Anglo-Portugese alliance stayed intact as a strategic issue, as Portugal was poorly defended and the British did not need more reason to draw the Spanish into the war.) Franco had presided over an incredibly bloody civil war and had only stayed neutral in the 2nd world war because the Germans thought his conditions for Spanish military help were unfeasible (Rumor is Hitler once stated he'd rather have teeth pulled than continue to deal with Franco). \n\nFour years after the end of the 2nd world war, when the North Atlantic treaty was signed, few people had forgotten had close Spain was to becoming a full-fledged member of the Axis.\n\n"
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42asda | why do politicians owe favors to their donors? | [deleted] | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/42asda/eli5_why_do_politicians_owe_favors_to_their_donors/ | {
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"Let's look at it at a \"before presidency thing\", first. To get to that point you have held one office or another multiple times. You would not have gotten past the first if you were known not to \"repay favours\", as you would get no donors the second time. Now, to the presidency. Let's assume you decide \"OK, I'm here, no more sucking up\". Can you get any work done? Not really because EVERYONE else needs to still suck up to those campaign funds. So you get nothing done and when your one term is over you find no jobs waiting for you on the other side. \n \nAs for evidence? It is hard to tell. Being able to \"follow the money\" in a lot of cases is difficult, although others are less so. ",
"The concept is relatively simple, you're running for election and company X likes your stance on one or more policies, so they bung you some money to help your campaign. You win, work to enact the policies you want and company X is happy.\n\nRe-election is coming up and you need money to fund your campaign, but this time company X wants something that your constituents aren't so fond of, but if you support it they'll bung you another briefcase of money for your campaign. If you don't come out in support of it however they might go talk to the guy running against you and see if he'll be interested in a briefcase of money, something that's clearly not good for you. Clearly money is changing hands in exchange for policy support in this scenario but it's not always that obvious - until someone comes out for or against something it can be hard to pin down exactly what their position might be (and therefore whether they have changed position in response to something), and so it might look like they're in favour of something that just happens to align with the goals of one or more of their contributors. \n"
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2iwapf | How far can an ant be removed from the anthill and still find its way home? | Driving away from a parking spot in a park, I see an ant walking across my windshield. I stop and let it off, but I've already driven 30 feet. Is that ant doomed to death? (I thought most ants leave trails behind them to find their way back home. Since the trail is now broken, how will it find its way?) | askscience | http://www.reddit.com/r/askscience/comments/2iwapf/how_far_can_an_ant_be_removed_from_the_anthill/ | {
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"This has been asked a lot before so if you want deeper answers you can look them up. Basically if an ant doesn't know where it's trail home is it will start wandering around in random(ish) directions trying to find it. IIRC, they also have a good ability to remember landmarks, so that can help too.\n\nIf they are really far away and can't find their home then yes, then they may wander until they die. They may find another colony that they can assimilate into, but more than likely they ants their won't accept the foreigner and will attack and kill it (even if it's the same species possibly.)\n\nSo to answer your question of how far away, it depends. If they are a really long ways away, but get lucky in their random search they can find their way back. In general, I've seen estimates hover closer to 100 or less meters. It's actually a neat direct application of some of the algorithms in computer science if you want a more rigorous way to think of it."
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333omt | why do planes take what seems like huge detours instead of straight lines to the destination? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/333omt/eli5_why_do_planes_take_what_seems_like_huge/ | {
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"The flightpath of the plane looks curved on a flat map, but since the planet is curved that line is actually the shortest path.",
"Airplanes take [Great Circle paths](_URL_1_), the shortest distance between two points on a globe, effectively a straight line. And when you look at the globe, they do look like straight lines. But when you flatten the globe into a map, [they get distorted](_URL_0_)",
"A straight line on the surface of a sphere looks curved when you flatten the sphere out. \n\nA clearer example maybe - ever seen [a picture like this?](_URL_0_) That's what the orbit of a satellite looks like when flattened out onto a map. ",
"They also seek out wind, ie jet streams etc. Picking up the jet stream can reduce actual flying time and increase fuel savings. A line between two points isn't exactly the shortest route. \n\nImagine you had to cross a field to get to a certain point on the other side, sure, the shortest route might be straight across the field, and the longest might be walking around the edge. Now for the 'what ifs'. \n\nWhat if I told you that the field had a hill, bushes, scrub and a drain in the middle, but around the outside it was a concrete footpath, which might be quicker then. It is exactly the same for aircraft. the straight line might look quicker, but there might be hills/mountains in the way that adversely affect weather conditions. There could be a military no fly zone in between. \n\nWhen you are flying into and out of Melbourne, AU northward. you tend to come through a cutting, all air traffic is filtered through this cutting, otherwise any traffic heading towards Sydney has to deal with issues over the Great Dividing Range which impact weather systems etc. ",
"1. To catch wind or jet stream to conserve fuel and more speed. \n2. Avoid crashes and military.\n3. In a sphere for planes it's sometimes faster based on rotation of planet. Exp: from Europe to US some will go near arctic and go across there because it's a small horizontal flight then and they avoid the most of earth's rotation.",
"As someone very much in the know in the aviation industry, there's a few factors:\n \n \n1: Weather. Planes don't like flying through storms, and they also dodge areas of turbulence so passengers get a more comfortable ride. \n \n \n2. Air traffic have routes for aircraft to follow to dodge military airspace, and for a more efficient flow in and out of high volume areas. Why did you have to fly in a big circle around the city? Because there were a lot of other planes landing and taking off coming and going in all directions and that was the safest and fastest way for you to get to the runway.\n \n \nIf you're interested feel free to bombard me with questions. However I will do my best to answer them in such a way as to not give away my occupation ;)",
"Even though modern GPS allows planes to travel point to point airlines still file flight plans that are based on \"roads in the sky.\" Over land planes fly routes based on ground transmitters that form airways. Over the ocean planes file routes that allow traffic to flow all together. This prevents crossing traffic at the same altitude. ",
"Because the map you're looking at is flat, but the Earth is actually spherical.\n\nAirplanes fly on, or close to, great circle lines, which are geodesics (shortest possible lines) across the Earth's surface. If you viewed the Earth from directly above a great circle line, it would look straight. However, when you look at it from any other angle, it curves with the Earth; and if you try to project it onto a flat map, it tends to end up looking curved because the corresponding points between the Earth and the map don't match up in a way that preserves 'straight' lines. This is also the reason why, for instance, Greenland looks so big on a world map.",
"To travel from one place to another on the ground, you take roads. Some of those roads will be one way lanes, some roads will cross each others. When there is bad weather some roads will be flooded and wont be available. When there is construction work, some roads will not be available either. The same is true for the sky. Planes travel on imaginary roads, and will avoid lanes affected by bad weather, or 'construction works' (war affected countries, military exercises, really busy lanes]. The traffic police [air traffic control] might also choose to send you on a different road, one that is not as busy.",
"In short, because you are squishing and stretching a round Earth onto a flat map, paths get distorted too. Also, sometimes you have to follow traffic, like a highway in the sky, or turn to go around weather. At the end, you have get in line with the other planes, and point down the runway in the correct direction.\n\nI'm actually unclear with what you mean in your question about \"huge detours\", so I'm assuming you asking about the main part of a long distance trip and why on a map the path appears curved? Let's use Los Angeles to Tokyo as an example.\n\nHere is the path for ANA 5 on April 18: _URL_2_ compared to _URL_4_\n\nYou can check this yourself with a globe (or any large enough ball, like a soccer ball or basketball) and a piece of string. If you want to go from Los Angeles to Tokyo, from just a regular map it looks like you'd want to go straight west across the Pacific, right? Take your string and put it on those points, set the string along that east-west line in the Pacific, and then pull on the string until it's tighter. The line will go north towards the North Pole.\n\nMore on the great circle stuff can be found here: _URL_1_ \n\nBut that's if you were the only airplane in the sky, and a lot of other simplifications (such as how far you can go away from an airport you can divert to if one of your two engines fails). For all the transatlantic flights, there are the [North Atlantic Tracks](_URL_0_) that are published every day depending on the wind. This is to make the flights go faster and burn less fuel by avoiding headwinds and favoring tailwinds.\n\nIn busier airspace you might have defined navigational waypoints that all planes follow from one region to another. _URL_5_\n\nFurther reading: _URL_3_",
"Because flying over certain countries will get your plane shot out of the sky quicker than you can say \"allahu ak--\" you're dead.\n\nAlso, states and stuff have no fly zones for security that mandate circumnavigation. ",
"One item here that might have been mised. An aircraft fueling up in NYC has to pay tax for all that fuel. If they burn it over international waters or say Canada/Mexico they can file for a tax refund for the fuel expense outside of the country of purchase. Business are built on this; calculating flight plans and processing the tax return for say Delta, Dragon Air, etc.\n\nThis might make an aircraft traveling from Florida to Canada take a detour to international waters for the haul up.\n\nFiling up a 777 is costly.",
"When i travelled to thailand we had to fly around iran. They arent fans of commercial planes using their airspace.",
"I believe I watched something saying it was to do with the rotation of the earth and also weather in short.",
"Many of the above answers are correct. I wanted to include an example. Emirates flight EK226 flies from San Francisco to Dubai. It will take a detour around Ukraine:\n\nTo the north and east: _URL_1_\n\nTo the south and west: _URL_0_\n\nThe plane will fly over Iran rather than Iraq (active military area). ",
"Hi, \n\n < atc guy\n\nThey have highways in the sky. Shit would get ugly quick if everyone just went where they wanted. Think if we didnt have stop signs or stoplights or roads even but we all had cars still.",
"Air traffic controller here. Basically there are navaids that give a radial (360°) and DME (distance measuring equipment) to an aircraft. Utilizing this, we have fixes mapped out in the sky at a specific radial and DME that can connect to each other much like planning out a long distance trip in a car. On top of that we have jet routs and victor routs that start at certain navaids going out at a certain radial, much like highways in the sky. This helps keep things organized in the sky along with altitude restrictions that we use to keep separation between aircraft. These are IFR, (instrument flight rules) and are used by anyone from aircarriers ie. Delta, American Airlines etc. to anyone trying to get from point A to point B in a safe, expeditious manner. ",
"Everyone seems to forget the reason we fly waypoints and not direct routes is so you can fly fixed headings. Sure there are reasons for traffic, weather etc, but forget great circles and projections etc. Planes fly way points that map the most direct route possible with out requiring the constant heading changes. To fly the most direct route would be require infinite heading changes to compensate for the curvature of the earth.\n\nIt would be easy to fly direct if the earth was flat!\n\nEDIT, Just to clarify. The only place you can fly a great circle without constant heading changes is the equator. If you fly from north to south, each time you pass over the poles, your compass would swing from north to south. Any angle between the poles and the equator means the compass will change to follow magnetic north.",
"Most of the answers in here are wrong.\n\nContrary to popular beliefs, airplanes have their own \"roads.\" We call them \"airways\". Duh. [Pics](_URL_0_)\n\nThe first picture is a simplified version of a \"chart.\" A chart is what pilots are given prior to flying. (pilot redditors, correct me if I'm wrong) It also includes other information as well, eg. fuel weight, passenger number, cargo weight, weather, etc.\n\nBack to the first pic, notice the small triangles? Those are called waypoints. They are mostly imaginary points, same with the airways, but some could be a real landmark and such. \n\nHow do pilots remember all of this? They don't. They type it (the waypoints) into an MCDU (a computer basically) prior to flight, then they set it to auto pilot. Bam! You've arrived at your destination. Easy right? You would think that wouldn't you. As you may see in a cockpit, there are so many things pilots need to know. Computers only help with the mundane and repetitive tasks. tl;dr piloting is hard. \n\nEdit: I didn't quite answer the question. Basically to avoid weather and/or air traffic. ~~ATCs (Air Traffic Controllers) will have a hard time if planes fly however they want and where ever they want to. Waypoints and airways help organize air traffic. Imagine a ten lanes highway without road traffic markings. Won't be good for your health.~~\n\nEdit2: word",
"Many have answered your question assuming you were talking about the curvature of the earth. I think this question is often asked more when you look at airliners flight plans, and where they are flying. The simple answer is that airways are defined to allows for the smooth, uninterrupted flow of traffic. This allows for easier traffic separation, and terrain avoidance. Far easier to guarantee than if all traffic was a free for all.\n\nIn the US, there are two sets of flight rules, visual (VFR) and instrument (IFR). All airliners use the IFR system, in which separation services are provided by air traffic control. The FAA defines these routes, and it is expected if you file an instrument flight plan that you use them. If you look at this [website here](_URL_0_) you can see the airways for yourself. If you have planes flying defined routes, you only need to worry about intersections of these routes to ensure separation. If planes are flying direct (which is a possibility when ATC allows for it) you need to worry about traffic separation at all times.\n\nA flight from Boston to NYC for example, may take the form of [this.](_URL_1_) When you are talking about longer distances, you try to keep it as straight as possible when planning, however following airways causes you to sometimes have to deviate, especially in areas where no airway may be defined in the direction of your flight. These may be the detours you are seeing.",
"Planes fly over the North Pole or South Pole, depending on where it starts and where it's going, because the earth's roundness means travelling over a straight line would take longer, and going to the top and down would be much shorter. This porbably explains it better than me.\n\n_URL_0_",
"Lots of people have explained the two parts to this answer: established air routes (which may be less direct for shorter flights, but on really long flights most segments are at least close to a great circle), and the shortest distance between two points looks non-straight on a typical mercator projection map.\n\nHere is an excellent video that visualizes both of those points, but especially the second one: the paths that looked curved on the in-flight map is actually pretty close to the shortest, straightest one possible.\n\n_URL_0_",
"Airline Pilot here and Woot ! \nLet's see *ahem clears ELi5 voice*\n\nWe use highways in the sky called Jet ways (routes) and they are individually tailored to fit airspace requirements ( avoiding restricted/military areas) and navigation performance needs (Signal coverage). These routes can be viewed as a highway, some are near a destination and some are not.\n\nThen ATC ( Air Traffic Control ) issues STARS ( Arrival routes ) that help the plane transition from the \"highway\" to local navigation points so it's easier to manage traffic to a landing runway.\n\nTherefore, LOTS OF TURNS to sequence traffic or else everyone will be packed like sardines at the destination airport mmmkkaaay? ",
"Go to _URL_0_ and cluck the world high overlay in top right. You will see all the paths planes must follow to help with sequencing. On top of that, and what you don't see, many large airports have published approach procedures called STAR, or standard arrival, which allows the air traffic controller to assign that arrival to multiple aircraft with the same speed and essentially forget about them. You can also see on sky vector the large MOAs, which are military operating areas, that planes should go around because there are uusually jets doing high speed maneuvers and won't be looking out for you. There are also restricted areas you can't fly in, like bombing ranges or certain factories, etc.\n\nSource: I'm an AF pilot",
"Planes do their best to follow straight paths from city to city. These paths might look curved on a flat piece of paper, but if you look at a curved globe, they're straight paths!\n\n Sometimes though, planes can't follow that exact path if there's either weather or other planes in the way. Planes can't fly through tornados and they definitely don't want to crash! So sometimes the planes will have to turn off of their route for a little while. \n\nBut things flying at such high speeds as these planes can't turn like you and I can on the ground. They're moving so fast that it takes a long time for them to get out of the way. That's why planes end up going so far out of their way during a trip!",
"Planes historically have navigated by the use of land based radio beacons.. VORs... these are scattered across the US and world and planes fly point to point with them...(VOR's have limited range).\nThis is why you often don't have a straight direct path. \n\nWith modern GPS, planes are much more capable of flying direct to a destination... but somtimes traffic flow patterns and restricted airspace prevent that.\n\nSource: airline pilot.. and yes, I didn't account for everything..and i dumbed it down quite a bit..",
"I work in the industry. There are many reasons why:\n\n* Think of the sky as containing a series of highways. Like the highways on the ground, they're never perfectly efficient for a number of reasons - radar coverage, control jurisdiction, restricted airspace, terrain, and legacy purposes. The aircraft moves based on routes and waypoints. When you file a flight plan, you must state what waypoints you will be using. You can deviate from the plan while flying, but you still need to follow waypoints.\n\n* Radar coverage. If you're in an area without primary radar coverage, the controller must be very cautious to ensure there is ample room between you and other aircraft. (There are means of using only secondary surveillance for separation, but this is relatively new - WAM and ADS-B)\n\nThe north Atlantic tracks between Gander and Shanwick are an example - this is 60 nautical mile, procedural separation - there are no radars in the middle of the ocean. There are only a handful of tracks you can take between the US and Europe. This is to ensure that each aircraft has at least 60 nautical miles (~70 miles, or ~111km) between them. The controllers don't know exactly where the planes are, they just predict/guess. Pilots radio their position every 10-15 minutes (HF or satcom) or it is reported over CPDLC ADS-C every 10-15 minutes.\n\n* In the terminal area, you must consider the current runway configuration of the airport. If the airport is doing takeoffs from 1R and landings on 1L and you're coming in from the north and it's not a tiny airport, you can't just willy-nilly say \"I'm coming from the north, give me 19R.\" (19R is the same as 1L, just the opposite side.) The pilot will have to circle to the other side of the airport and begin an approach on 1L.",
"I work for an airlines and one reason I was told is that planes want to be traveling over as much land mass as possible in case of an emergency. This doesn't fully answer your question, but it explains some over the water type of routes.",
"Since this is ELI5, the simplest answer is we seek the quickest time between cities, not the shortest distance. Planes consume fuel by the minute, so there are applications that calculate the most efficient route based on the wind patterns at cruise altitude. The higher we fly the more efficient we are as well, but the maximum altitude allowed varies with weight. My passenger jet gets lighter (consumes fuel) by about 100 lb per minute on average.\n\nSorry I can't link on my tablet, but search for winds aloft charts for 250mb, or roughly 36,000 ft altitude to see the air currents we deal with.\n\nThere are also set flight patterns into and out of major airports for traffic flow and to avoid certain airspace for various reasons.",
"The same reason we don't let cars go from point A to B. It would be chaos. At those speeds, there would only be enough time to say, \"What is tha...\"",
"I think another problem that planes have to deal with when taking detours would be radar. Currently planes still use ground-based radar tracking, which has a limited range. This means that they have to stay within a certain distance from the coast or simply be off the radar. This leads to things like the Malaysia Airlines disappearance, where the plane was off the radar at a certain time and then it crashed. \n\nCurrently places like the FAA in the US are trying to implement satellite based radar that will allow planes to fly in a straight line to their destination and plan their routes to avoid interference with other planes.",
"Air Traffic Controllers need things to be organized in such a way that they can actually...control...the airspace. Thus there are often lanes/highways/whatever you want to call them where they place aircraft. This makes things more manageable. There are also rules like restricted airspace and of course adjustments for things like weather or emergencies. If you are flying somewhere that is not busy airspace, you can often receive clearance to take a more direct path.\n\nJust imagine an airspace with hundreds or even thousands of aircraft at different altitudes, flying at different speeds, and going different directions. Imagine that they have different rules for what they do in different situations (say, military aircraft vs civilian aircraft). Thinking in 3D is hard enough, this is like 3D+.",
"The great circles are the way to go per my son who flew\nthe C-5 in the Air Force.",
"Not a single link to an arrival routing... For flights within the continental U.S., arrival and departure routings can talk airplanes from New York to Chicago or farther without ever having followed a direct path to the destination. The [PAITN FOUR](_URL_0_) arrival begins over flint Michigan and would be used by all aircraft approaching from the northeast. If this routing experiences heavy congestion, aircraft could be re routed to the south to join with another arrival routing, adding to the apparent detours in the interest of *saving* time (like avoiding a traffic jam by taking a longer route). While some planes do fly great circle paths, this routing is usually reserved for trans oceanic flights where congestion is less, and the distances are greater; they usually will terminate with a standard instrument arrival, but a 50-100 mile detour looks much less significant after a 3,000 mile flight.\n\nEdit: aircraft also have some pretty strict limitations when it comes to the type of weather they're able to fly through. It is not unheard of or even really uncommon for aircraft to divert by hundreds of miles to avoid an advancing line of thunder storms.\n\nEdit2: if you want the real skinny on what's happening when planes do this, come on over to /r/flying where the pilots of reddit will set you straight on what's really going on in the skies over your home town.",
"And here I thought it was because they would need to tunnel to go in straight lines..",
"Hello, real live pilot here! This post is sort of old so I'm not sure if this will get read, but here it goes!\nA lot of people keep answering that the detours we take is because the world is round, but I think you are already aware of the shape of our planet, so I will go on to explain some of the real reasons. Some of the common ones would be to avoid certain air spaces, weather, and other air traffic. For example, this morning I was flying from one Midwest state to its neighboring Midwest state, and we were asked to change our heading 15 degrees to the left, to avoid another airplane. In areas with heavy traffic you have to do this more often. As far as the weather goes, if you are in a larger airplane you have the range and ability to get around bad weather, rather than cancel the whole flight. Also, if you can get a good tail wind, you can save a lot of time, even if you have to go out of your way. With the airspace, there are many different kinds, but to keep this super super simplified there are some that you are not allowed to enter at all, some for the military purposes, and some that are just too busy to handle you. \nThere are also still some planes (mostly smaller general aviation planes) that do not have a GPS in them, and so they must navigate using ground facilities called VORs. These send signals out in all directions that a plane picks up, and you can use them to zig-zag around. \n",
"In the true ELI5 sense: because you are looking at the flight paths on a flat map, but the earth is actually round. ",
"There are two different charts that can be used for navigation:\n\n\nOne is a \"mercador chart\" and the other is a \"great circle chart\"\n\n\nThe voyage is planned using a great circle chart, this chart takes into account the curvature of the earth with all lines of longitude coming together at the poles. The navigator will draw a straight line from point A to point B on this chart, this is the course that the plane will actually be flying. \n\n\nMost people are not familiar with a great circle projection (the do look kinda weird) so instead they show you a \"mercator projection.\" This is the way most maps at school are drawn. On this projection all lines of longitude are evenly apart and the curvature of the earth is not taken into account. When the coordinates from the great circle chart are placed on a mercator chart it gives the appearance of curved line when in reality it is the most direct route to the destination.\n\nSource: I am a navigation student\n\n\nTL;DR\n\nPilots use a special map that is projected differently than what we are used to. The map that most people grew up with does not take into account the curvature of the earth, so therefore it just appears that the plane is taking the long way around whereas from the pilots perspective it is actually the most direct route to the destination. \n\n",
"They are taking straight lines, you're just thinking in only 2 dimensions.",
"Lots of reasons. Here's a few.\n\nBigger airports have what's known as Standard Terminal Arrival Routes (STARs). This manages the traffic that arrives at the airport in a predictable fashion which makes things easier for Air traffic control. When they leave they fly a Standard Instrument Departure (SID). Of course this means aircraft can't depart or arrive in a straight line because that wouldn't allow them to be sequenced with other traffic.\n\nWeather is another good reason. Often times a line of thunderstorms requires significant deviations made by the aircrew to circumvent the extreme weather. \n\nMilitary airspace, there are plenty of areas of restricted airspace in the United States (and I would assume other countries) that commercial aircraft aren't allowed to fly through. \n\nSpacing, similar to the arrivals and departures air traffic controls primary job is to keep traffic separated. So even though an aircraft may wish to proceed directly to its destination, ATC can't allow it because it would create congestion.\n\nI'm sure there are a few more reasons, or ways to explain what I mentioned but these are the big reasons I can think of off the top of my head.",
"Simple answer.\n\nAircraft generally follow [enroute charts](_URL_0_) and their associated airways.\n\nIt's obviously much more complex than this in reality but that is the easiest way to explain it.\n\nSource: I'm a commercial pilot.",
"Actually just watched a Netflix documentary on this last night. Doesn't make me an expert by any means, but provides some knowledge. Most of the routes planes take nowadays has to do with the way flights happened in the early days of plane travel. There weren't enough Radar towers to accurately track plans if they took the most direct route from A to B, so they routed all traffic along \"corridors\" that flew by the instillations that were built, allowing them to keep an eye on traffic. Otherwise, plans could/would crash and no one would know/realize until much to late, and they wouldn't be able to locate where exactly a plane crashed, because no one actually knew where it was. Obviously, this is outdated nowadays and it's something the FAA is looking into fixing/resolving.",
"I am an aircraft dispatcher and no we are not air traffic controllers lol. What we do is create flight plans from point A to point B using jet routes that have already been mapped out all across the globe. When we make a flight plan, we try to take the most direct routes to the destinations but we also have to take into consideration what weather could be blocking our path and re-route them around storms. Also when it comes to landing and take off, we use SID's and STAR's (standard instrument departures and standard terminal arrival route). When it comes to those, we try to give the pilots right SIDS and stars that will put them directly in line with the jet route upon takeoff and when coming in to land. Some SIDS and stars have turns in them for the pilots to stay on the course to avoid air collisions. Also next time you are on a flight and you go into holding, don't blame the pilots for it because they are only trying to keep everyone on board safe due to the incoming and outgoing traffic at the airport. ",
"Take a string and put it on a globe from one point to another, you will find that curving a little actually makes it a shorter route.",
"This is because the earth is a sphere and the closest distance between two points may not be the actual closest distance as you see on a 2d map. If you ever get shipment from overseas, you'll notice that many of your items first arrive at Alaska. (In fact, 90% of the industrialized northern hemisphere can be reached within 9.5 hours from Anchorage.) In order words, the airlines save fuel and money, and you also save time by arrive at your destination quicker, a win - win situation) \nSecondly, you may notice planes sometimes stay very close to areas of lands instead of passing over a big chunk of ocean. I believe that this has to do with safety, in case of a failure, planes can request emergency landings near land, instead of landing in sea (which is many more times challenging).",
"I'm a helicopter pilot so I might be able to shed a little bit of light on the matter. For the most part ATC will detour the aircraft around weather or other traffic. Usually if the local traffic control has to deviate around weather this will also change the flow of traffic coming in and out of the area. ATC is also responsible for the separation of the big airplanes and this takes a lot of coordination between their own, and other control facilities. \n\nOn rare occasions the airplanes may be put into a holding pattern before landing. Basically you'll fly in a planned circle as a planned altitude waiting for your turn in line (if they are backed up) or for the weather to clear. \n\nMost of the navigation is through GPS now, but we still have ground based nav aids and with those nav aids you have to follow certain routes called victor airways. Basically they are like huge roads in the sky between each navigational aid. Sometimes to hop from navaid to navaid might not be the most direct route. \n\nHope this helps. ",
"There's also a post showing recent traffic over Britain's airspace. That should help explain it.\n\n_URL_0_\n\nEdit: link added",
"Because of the curvature of the Earth, the paths taken usually are straight and the shortest. The diameter of the Earth is smaller as you get closer to the poles, so flying closer to the pole can cut time off a trip. Also, on flights the cross the oceans, planes tend to fly as close to land as possible in case of an emergency.",
"Long story short... Pilots account for the rotation of the earth when writing their flight plans. ",
"Firstly, the curvature of the earth distorts the path, so it may not look like a straight line, but if you take a string and stretch it between your destination on a globe it will most likely match up.\n\nSecond, they need to avoid other aircraft, and also travel above certain radio beacons/control centers, and may alter their paths to accommodating for this.\n\nThird, winds aloft can be predictable in certain areas/altitudes, so they may be taking what seems like a detour in order to be more fuel efficient/actually save time due to tailwinds.",
"There are landing approaches that are always less direct but meant to make traffic and arrivals/ departures more predictable and safe given the volume of air traffic. Flying direct would t be safe, there are also holding patterns which can be implemented based on volume and weather which will make routes appear less direct than optimal. ",
"There's a bunch of reasons.\n\n* Firstly, traffic. Planes generally try to avoid crashing into each other.\n* Secondly, geographical features. Planes try to avoid coastlines because of turbulance, mountains to avoid crashing, and volcanos because those tend to mess things up.\n* Weather. No-one likes flying through storms or thunderclouds.\n* Holding patterns. If there is an emergency, other planes will be told to stay clear for the time being.\n* Runways. Not all of them are perfectly alligned, and planes can't turn on a ditme, they need to take a \"sweeping approach.\"\n* And, then, of course there is the curvature of the Earth, but others have covered it well before me."
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"http://i.dailymail.co.uk/i/pix/2012/04/25/article-2134979-12C1E333000005DC-706_634x377.jpg",
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"http://www.cgg.com/data//1/rec_imgs/9550_orbits.png.jpg"
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"http://en.wikipedia.org/wiki/North_Atlantic_Tracks",
"http://en.wikipedia.org/wiki/Great-circle_distance",
"http://flightaware.com/live/flight/ANA5/history/20150418/1935Z/KLAX/RJAA",
"http://en.wikipedia.org/wiki/Category:Air_traffic_control",
"http://www.gcmap.com/mapui?P=lax-nrt&MS=wls&MP=o&DU=mi",
"http://en.wikipedia.org/wiki/Airway_(aviation)"
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"http://www.flightradar24.com/data/flights/ek226/#5fef81f",
"http://www.flightradar24.com/data/flights/ek226/#60362bb"
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"http://imgur.com/a/UKjN5"
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"http://skyvector.com/?ll=40.23760536954836,-97.63110351860558&chart=302&zoom=10",
"http://skyvector.com/?ll=41.68357908546022,-72.31613159566378&chart=302&zoom=4&plan=A.K6.KBOS:F.K6.MILIS:F.K6.FOSTY:V.K6.ORW:V.K6.MAD:A.K6.KBDR:A.K6.KLGA"
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"http://en.wikipedia.org/wiki/Polar_route#/media/File:PolarRoute.png"
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"skyvector.com"
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wwv6e | seriously, how do cell phones work?! | How does a phone (a bunch of wires, glass, etc.) call someone across the country instantly?
Edit: the one thing that still blows my mind, is that all this is done by electricity. Period. I work on all fighter aircraft for the air force. (Computer systems specifically) and to this day , thinking about how intense shit like this really is....BANANAS | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/wwv6e/eli5_seriously_how_do_cell_phones_work/ | {
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"There are cell towers all over the place and each one covers a certain area on the ground, which is called the cell. When you travel into the next cell, that tower then picks up your signal and continues your call.",
"Sound energy becomes electricity and then the Tesla fairy takes it across the sky.",
"First of all it's not instant. It's something like one twentieth of a second from the time you speak until the other person hears you, and it depends on how far away you are from each other. It takes time to transmit information, so no kind of communication is instantaneous.\n\nStep by step here is a basic overview. If there's any specific part of this you are curious about I can explain more.\n\nThe sound of your voice goes into the microphone.\n\nThe microphone converts these sounds into electrical signals.\n\nA part in the phone called a ADC converts these signals into a stream of numbers.\n\nA tiny but very fast computer in the phone does lots of math with the numbers to process the signal, compress the information so there's not too much to transmit, and package it into a format that the phone company can understand. \n\nA radio in the phone transmits these numbers onto the airwaves.\n\nThe nearest cell tower receives the radio signal.\n\nA computer at the cell tower then retransmits the numbers, in the form of light waves, into cables that run all over the country. Lots of fancy equipment in big air conditioned facilities all over the world pass this information along to its destination. \n\nAt the other end, the reverse process occurs until the sound you made finally exits the other person's phone through its speaker.\n\n",
"The instantaneous part is due to the radio waves travelling at the speed of light. At this speed, the wave can travel around the world 7.5 times every second. The signal generated by the phone is not powerful enough and will not be able to travel across the globe on its own, and will need to be passed along by cell towers.\n\nWhen you first dial a number, the phones and towers involved must do some \"handshaking\" in order to connect you with the person you are calling and not one of the millions of other people who also have a cell phone. This is the cause for the relatively long delay before their phone starts ringing. After the connection is made, the rest of the conversation will take place with a much lower delay.",
"Like all my ELI5, I'll go big picture complicated, come back to an ELI5 answer:\n\nSo first your cell phone, minus all the \"smart phone\" compartments. Is basically a wireless phone that has a very powerful radio in it. Mattering which country you are in, that radio will be locked to set a frequency which it can connect to. The status bar will show the signal strength, and also the type of network connection (frequency) you are currently connected to. Your radio is constantly looking for a signal, and determining the signal strength. When you make a phone call, the number you dial is like an IP address on your computer. It gets sent out over the airways to a radio tower, which then sends that signal to a switch. That switch will look at the phone number just like it does an IP address. The first three numbers are an area code, and if that area code is for that area, then it moves on. If it isn't, it will look through a registry to find the location of that area code. It will then transmit the call to either a satellite (if it is a very long distance, or if there isn't a fiber connection to that site) or over fiber to the correct location. \n\nThen mattering which way it comes in, it will then take in that signal, look at the number, see that it is the right area code, and then look at the next three numbers, and then the final four. These numbers will be connected to your SIM card. (The SIM is hugely important in this process, it sends out what your number is, controls what network you can connect to, and also holds information such as IEMI, and other vital information for your carrier subscriber. I can go in detail on the SIM card if needed) so it will be able to find that number by sending out a signal looking for that number. Once it is found, the cell phone communicates back that, yes, this is that number, and the cell tower will say you have a call. The call is then patched through, and your voice is transmitted, over radio, then over a wire, then possibly over fiber, and then possibly back to radio, and then to a wire, and finally wireless to the other end of the call. This string of events are carried out back and forth over the whole process of the phone call.\n\nNow how does your voice transmitted as radio waves, and then changed into other forms, back into radio waves, come out as your voice on the other end? Well the radio in the phone takes in the signal and then is able to determine from the changes in the signal coming in what the person's voice is like, and what the person is saying. \n\n\nSo now for the ELIY5 part: Basically your phone has this big radio in it, that sends your voice over the air, and it is sent all over this country to another person's big radio and it sends back and forth.",
"My problem has always been understanding sound - > electric signals - > sound. I do not understand how I can speak, something can pick that up and turn it into not my voice then relay it again as my voice.",
"One thing I've never understood. If you're calling another cell phone, how is it possible for the 'signal' to KNOW where the other cell phone is located? Are cell phones constantly relaying their position to a phone mast or something?",
"Basically you make a handshake with the base station telling it who you are and who you want to connect to in form of a telephone-number, it then does a lookup and finds out which SIM-card that owns that number and creates a connection. Now that you have a connection you can talk to the other person in form of a digital bitstream. A digital bitstream is your voice being translated to binary code. You know how a soundwave looks like, right? \n\nImagine your soundwave being chopped up into tiny pieces, then you can take each little piece of that soundwave and find out how 'tall' it is, so if the piece you got is really high up on that soundwave, you would assign 255 out of 255, and if the sound wave is on the bottom it would be 0 out of 255. The higher the quality of the signal is, the tinier the soundwave gets chopped up. So now that we can build a soundwave out of values we can send each of those pieces by translating them to binary and sending them one by one in the right order, so if we have the first piece which is 130 we would translate that to 10000010, then we would translate the next piece to binary and send it as piece number 2, and it goes like that until the connection is broken by someone hanging up. When the other cellphone receives this bitstream it would translate it back into soundwaves so that the other person can understand it.\n",
"Maybe I missed it, but how does the individual phone know which data in a given frequency to \"grab\" out of the air?\n\nFor example, 10 phones all receiving 10 different types of data. How does my phone know that a certain series of bits make up the photo I'm downloading, while another set of bits is going to someone watching chocolate rain?\n\nDo the bits have header data to specify an IMEI? or are different sets of data sent on very specific frequencies within a broader range?",
"Watch your mouth!"
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