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41b837 | why don't engineers have to factor in the curve of the earth? | [deleted] | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/41b837/eli5_why_dont_engineers_have_to_factor_in_the/ | {
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"/r/askscience might be a slightly better place for this. You could more likely get literal engineers to answer this"
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2cd6cu | what is the relation between tequila and worms? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2cd6cu/eli5_what_is_the_relation_between_tequila_and/ | {
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"It's not tequila, it's mezcal. And supposedly when making the alcohol with agave, the worm is supposedly eating the agave and accidentally makes it into the mixture. But really they're added for flavor and color. And to add to the urban legend."
]
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3arujb | what's the deal with charcoal toothbrushes? what makes them better than normal ones? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/3arujb/eli5_whats_the_deal_with_charcoal_toothbrushes/ | {
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"Here are the claims they make.\n\n- rapidly whitening teeth\n- deodorizing and removing plaque\n- preventing bad breath\n- preventing harmful bacteria from growing within the brush"
]
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f4m8yq | if you spent enough time in a foreign country, could you pick up the language like your original language without having to take classes or whatever? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/f4m8yq/eli5_if_you_spent_enough_time_in_a_foreign/ | {
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"You would need someone helping you learn some new words but you do pick it up much faster and develop more authentic sounding accent easier.",
"Its possible, but it wouldn't be like a child learning. \n\nTheres a concept called plasticity in psychology that refers tonour brains adaptability and ability to take in new information. \n\nAs a child, the language centers of the brain are basicly blank and ready to learn the \"rules\" of communication from our parents and such. As we learn those rules and master them, they become concrete. We understand them and this is what we follow. \n\nAfter this point, it becomes harder to change the rules and add new ones. This is good in a way because it helps us keep what we know, but makes it harder to learn a new language with son many new rules.",
"Sure. But it depends.\nAt the very least, it would help to learn the basics of the language. For example, if the language *isn’t* Latin based, (written with the alphabet we use), it’s pretty hard to learn the script just by absorbing it. It’s possible, but time consuming, so I recommend at least taking a class on that. Once you have at least the basics of a language down, (ex: can read the script and know a few phrases,) Moving to a country that speaks the language is one of the best things you can do. Essentially, seeing and hearing the language constantly will cause your brain to devote more energy into understanding it. It is pretty frustrating being surrounded by words and phrases you can’t understand, but don’t let that discourage you. You’ll be able to pick up things in a matter of months.\n\nTL;DR \nTo answer your question: Yes, it is possible. If you spend enough time in that country, you will pick up the language, but it’s much, much more efficient to learn the basics of the language, then move to the country. Formal classes aren’t necessary, you can find stuff online, but learning something first does make it easier. If time really isn’t a factor, like you said, then you should be fine going without any classes. It’d just take a good amount of time.",
"Consider the example of foreign speaking students in US schools in the past. It was common to put the students in English speaking classes and let them flail until they understood enough to participate.\n\nIt's not easy on the new students, but immersion like this does work."
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3tkkjb | how does shock work? | i don't undertsand how shock works as "reviving" i mean, how cna something that can take someone's life bring it back to life?? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/3tkkjb/eli5_how_does_shock_work/ | {
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"A brief electric shock administered when the heart is in v fib, (sort of vibrating instead of pumping) can eliminate the v fib and restore the normal beating pattern if it works. If it does not work try again. It does not work with a heart in asystole, (not beating). The AED devices can determine if the heart is in vfib. They can talk anyone through the process with simple diagrams.\n\nIt only works during v fib, not asystole. Hollywood movies tend to get it wrong. If the heart is in asystole the AED advises, continue CPR. CPR and the AED do not work a lot of the time. But what else can you do?"
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2dnhlo | what is the real purpose of those radar speed signs on some roads? are they taking pictures of violators, or telling the police which roads should be patrolled? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2dnhlo/eli5_what_is_the_real_purpose_of_those_radar/ | {
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"several purposes.\n\n1) reminding people to slow down. especially for temporary speed limits like construction areas\n2) surveying traffic on existing speed limit zones to see if speed limit is viable\n\n\nto my knowledge, pictures taken by those devices are not pursued with a ticket. red light and turn light cameras are enforced, but speed limit not necessarily",
"It's like dog shaming but for drivers "
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23d20o | how can the moons gravity cause the tides on earth from over 380,000 km away, yet cannot sustain its own atmosphere? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/23d20o/eli5_how_can_the_moons_gravity_cause_the_tides_on/ | {
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"Particles of gas move really fast. The gas particles that would have made up the Moon's atmosphere were moving quick enough to escape its gravity, like we do with rockets. The moon's gravitational force (on its surface) is a little less than a fifth of that on Earth. That's enough to tug on the non-rigid oceans a little bit.",
"In the grand scale of things, the tidal effects from the moon are extremely small compared to the size of the earth and distance. Tides are just an observable fluctuation of a few feet of sea level, from the human perspective.\n\nThe escape velocity of gas particles with the moons gravity is really low, and generally, gas particles have high kinetic energy, thus, they can escape easily.\n\nIn summary, tidal effects are actually pretty small than what they are depicted to be.",
"The moons atmosphere is lost to space very quickly. Sometimes a sandal atmosphere develops from outgassing and radioactive decay, but it evaporates into space pretty quickly. \n\nThe moon causes tides not because it has so much gravity, but because it pulls more on one side of the earth than the other, and this imbalance causes the tides. Something of a complicated reaction to an asymmetrical system.",
"Think about it like this:\n\nImagine a very strong person holding up a very heavy weight. A very weak person comes by with a feather, and tickles the strong person. This can cause the weight to shake and move---maybe even to drop---but it does not mean that the weak person could hold the weight. \n\nThe moon-earth-tides system is similar. The moon by itself doesn't have the mass to hold on to an atmosphere. If you put gas all around the moon it would, sooner or later, all drift off into space. However, the seas are held where they are by the gravity of the earth. The moon's influence is enough to shift them around within the earth's grip, to tickle them about, even though the moon wasn't big enough to hold on to an atmosphere.",
"In addition to the other responses, there is also another mechanism working against the moon.\n\nTemperature is a statement about the average speed of the particles. The key word is average. This means that there will be some moving very fast, and others moving very slow. *Even if* the moons gravity is able to keep a particle of average speed within the atmosphere, there will still be particles with higher speed contributing to that average which can, and do, escape.\n\n This (momentarily) lowers the temperature of the atmosphere, though, because the faster particles are no longer contributing to the average once they've escaped. But, we have the same amount of solar energy heating the atmosphere, so its temperature should not decrease. So, the average speed of each molecule increases in order to achieve the same temperature as before. The process repeats the entire atmosphere has leaked away into space.\n\nWhile this scenario may seem far fetched, this is exactly why helium doesn't occur naturally in Earths atmosphere. The tides, on the other hand, do not experience any similar effect, and, as others have noticed, the gravitational pull causing the tides is modest at best compared to those required to retain an atmosphere.",
"The reason earth's atmosphere is stable is more than just gravity, it's mostly electromagnetic shielding.\n\nBasically, the earth has a magnetic field that's created by the rotation of material inside the earth's innermost layers. This is what gives us the north pole and the south pole, and it makes compasses to work. This field also creates a sort of shield against solar radiation and solar gases. Light and gases (think solar flares) from the sun are highly energetic, and when they hit the earth's magnetic field, a good deal of the energy is absorbed by the various pieces of the magnetosphere. This protects the earth from the high energy particles and light bombarding the earth.\n\nOn the other hand, the moon has a much weaker magnetic field than earth, so when it gets hit by the sun's light, most of the energy hits the moon itself. This actually has the ability to \"blow away\" atmosphere because there's enough energy transferred to the atmospheric particles that they are pushed by the particles from the sun, stripping away the atmosphere. This is a concept known as solar winds. Without a good magnetic field, which is usually generated by a liquid core like the earth's core, a planet will find it hard to sustain an atmosphere.\n\nBonus fact: the auroras in the night skies of the northern and southern hemispheres are actually created by the sun's particles passing through the section of the magnetosphere known as the magnetotail, which causes some of the particles to rapidly accelerate towards the ground at the earth's magnetic poles. Those particles collide with the earth's oxygen and nitrogen atmosphere as they race to the surface of the earth, changing the oxygen and nitrogen's energy levels, which causes them to emit specific colors of light.",
"The moon's effect on the oceans are about 1.5m or so, also known as the tidal swing, or height distance between the highest and lowest tide. 1.5m out of 380,000,000m is in comparison, a hair's breath to a half marathon.\n\n",
"why should it sustain its own atmosphere? just because earth behaves that way?"
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1t3mfi | why do newscasters/show hosts sometimes use the same phrases verbatim? | A friend sent me this video from Conan: _URL_0_
What causes this? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1t3mfi/eli5_why_do_newscastersshow_hosts_sometimes_use/ | {
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"In the case of that video, there are news services which the staff of these programs subscribe to which provide resources and even scripts on how to present stories. These are inexpensive and designed to fill gaps in programming. All of the subscribers get several of these each day or week and gets people off the hook for having to do real reporting.\n\nIn other cases, editors or political groups might send out talking points to programs which emphasize particular phrases which they are trying to establish as trends in conversations. One infamous example was the term \"death panels\" which was pushed very hard by certain interest groups and news outlets."
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byz15o | how long have animals and humans been dying from cancer? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/byz15o/eli5_how_long_have_animals_and_humans_been_dying/ | {
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"They've found Homo Habilis bones with tumors, and several varieties of dinosaurs have also been found to have cancers.\n\n So... forever?",
"Since their species have been formed. It’s from a cell formed incorrectly and while some current events are escalating the rate which it happens, the bodies of some beings millions of years ago made mistakes then and still do now."
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2wejse | why are designer brands like chanel and louis vuitton so expensive? are they made out of really high quality material, or is it just because of the company they come from? | Just wondering because my mom decided to look for a fake Chanel handbag online, and the prices for a fake was $200, which, for an Asian, is expensive as fuuuuuuuuuuuuuuuuk. So are these things made of legit alligator skin or something? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2wejse/eli5_why_are_designer_brands_like_chanel_and/ | {
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"I remember watching a documentary on this. Essentially the very top tier designer goods which are out of the price range of most of us are of a very high quality and which give the brands their reputation. \n\nThe second tier goods are the goods that are still expensive but that the masses can afford and are still relatively good quality but the costs are inflated because they carry the same brand name as the top tier goods.\n\nThe third tier goods are absolute crap that still have same brand label as the first 2 tiers of goods and therefore the prices are massively overinflated. For example, I bought a pair of La Coste Shoes that were essentially Dunlop Volleys with a $200 price tag because of the crocodile logo because I am an idiot and fell for the ploy.\n\nEssentially the brands make a loss on the top tier goods (that only the super wealthy can afford anyway) and we get suckered into paying too much money for the 2nd the 3rd tier goods because they come from the same label. "
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2fq8yi | how do the new 100+ flavor coke machines work? | I mean, I'm sure they don't have 100+ tanks of soda back there. How does it store all of the flavors? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2fq8yi/eli5_how_do_the_new_100_flavor_coke_machines_work/ | {
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"Soda machines don't use tanks of pre-mixed soda. They have CO2 canisters and flavor bottles and make the soda by injecting CO2 and the flavoring into tap water; that's why you can see the bubbles and flavoring as two separate streams as the soda comes out of the machine. \n\nSince the Coke Freestyle machine is large, it can have many different flavoring bottles, and uses a computer to coordinate which flavor bottle is used; the CO2 canisters are essentially constant since every soda uses them in the same ratio of CO2 to water. ",
"[Here's what the inside of one looks like](_URL_0_). A lot of those 100 flavors are just mixtures of two different syrups, so they don't need 100 different syrups.",
"It mixes the soda in the machine. With so many choices, you're not going to need as much of each flavor because it's unlikely that one flavor will get used up very fast. [This is what they look like inside](_URL_0_)"
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7ydlcc | why are directors praised for a good story? i mean, for good cinematography, sure. but they don't write the story. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/7ydlcc/eli5why_are_directors_praised_for_a_good_story_i/ | {
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"The story that is presented to the viewers is ultimately delivered via the director's choices. The same story in the hands of a less talented director wouldn't be as engaging and enjoyable for the audience. ",
"A story teller is complimented for a story they didn't write, and directors are kind of modern day story tellers.\n\nIn both cases they are being complimented for the presentation of the story, or how well they tell it, rather than the plot."
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cqxmtj | why does a person singing an e sound different than a person with a slightly deeper voice singing the same e? what makes it sound different? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/cqxmtj/eli5_why_does_a_person_singing_an_e_sound/ | {
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"In music its called timbre which is the quality of the note.\n\nThe E is the pitch, and is the main frequency that the air is vibrating at, but there are other frequencies that the air is vibrating at depending on how the note is made.\n\nIf its made by a tuning fork or an ideal speaker then its pretty much just that one frequency and the harmonics above it\n\nIf its made by a person then you get the E that the vocal cords are vibrating at, plus the frequencies that the chest is vibrating at which are different than the E. This gives an E sung by a large chested baritone a different quality than the same note sung by a smaller Soprano singer."
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25a15m | why are hangover poops so bad? | I've always wondered how alcohol can make your poop so bad the next day. I can't even think of a simple explanation | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/25a15m/eli5_why_are_hangover_poops_so_bad/ | {
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"Most alcoholic drinks contain lots of sugar. eating a ton of sugar, and getting dehydrated at the same time, no matter how you accomplish it, will give you the same gut rumbles. ",
"* alcohol and other depressants can paralyze your large intestines, interfering with how they function\n* alcohol use is often associated with eating junk food at odd hours, disrupting your digestive rhythm\n* alcohol can result in excessive urination and dehydration, which can also disrupt digestion"
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21ux8n | 3d printing of organs and various other things | How can we print working organ systems?
Edit: Changed text | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/21ux8n/eli5_3d_printing_of_organs_and_various_other/ | {
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"I saw a ted talk on this subject where they actually printed a kidney and were able to save someones life with the printed kidney. So its already been done if that answers your question.\n\n_URL_0_",
"I don't think actual muscle tissues could be printed, maybe the cartilage (hard tissue like your nose) could be. But 3D printers have been used to make models of faulty organs- identical to that of the patient, which has allowed surgeons to plan the operation before it goes ahead. ",
"This technology, while exciting, is still a long way from clinical use! The idea is that if we can grow new cells in a petri dish we could then us a 3d printer to arrange them properly to create a new organ! This is a very important part of working on synthetically replacing organs because if the cells aren't arranged correctly they do not function as an organ should.\n\nFor example: the cells in the kidney are arranged like little sieves and, put simply, this is how they function, filtering things out of the blood based on their size. So it's not enough to just grow new kidney cells in a petri dish! If we can use a 3d printer to arrange the kidney cells like a sieve, like they need to be to function correctly, then we could potentially grow new organs to replace non-functioning ones!\n\nEDIT: A lot of people here are saying this is surely not going to be possible for a long time but i can assure you it is in the works. Definitely not gonna be available in your local hospital as soon as the next couple of years but we're closer than you'd think! _URL_0_",
"We can't print organs. It's just a concept, and one that lacks enough evidence to suggest it's actually viable."
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ad5vsy | why is it that almost all cheap earphones happen to end up with only one ear bud working? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/ad5vsy/eli5_why_is_it_that_almost_all_cheap_earphones/ | {
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"Cables are cheap, so they wear out quickly, however it’s unlikely that both cables give out at the same time\n\nKeep using them, and if the first broke quickly, so will the other lol",
"A few years ago my apple earbuds stopped working on one side within 2 months. Those things aren't cheap :/ "
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3qogfm | where did the "tradition" of breaking a bottle of champagne on a new ship come from? | I'm not sure if it really happened, or if it's just from old cartoons I saw, but it seemed to be an old tradition to decree a vessel sea worthy by breaking a bottle of champagne or wine on it. Just curious where that came from and if there is any validity to it, | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/3qogfm/eli5_where_did_the_tradition_of_breaking_a_bottle/ | {
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"From what I can tell many civilizations have done this for ages, with the greeks pouring water on the boat during launch parties(Parties that celebrated the first launch of a ship) to gain poseidons blessing. Some peoples used animal bloods, interestingly the vikings apparently used human blood.\n\nSince a fluid to christen the ship seems to be a common theme, It looks like in 1797 the USS Constitution was launched with a bottle of Madeira wine. It seems from that point, as champagne became widely accepted as a drink of celebration it replaced the wine and with more globalization and standardizing in the past century and a half we've come to accept it as the common go to drink."
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ejv7ux | do liquids get digested at the same rate as solid food, or do they flow through the digestive tract quicker? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/ejv7ux/eli5_do_liquids_get_digested_at_the_same_rate_as/ | {
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"Liquids do get through the digestive system quicker. Liquids don't rely on the valve in your stomach that empties into your small intestine. As such, when people have disorders that slow down that valve (gastroparesis), they find that liquids are much more digestible. In particularly bad cases, they may go on an all-liquid diet. \n\nI also note that digesting means breaking down substance so they can be absorbed. So water doesn't really get digested at all--it's just absorbed unchanged. And sugars are either already in their simplest form or easily broken down. So the most common liquids we consume are already digested before they get very far into the digestive system.",
"The purpose of the stomach, in part, is to turn everything into a liquid. Once they leave the stomach to enter the intestines, there's no way for one liquid to pass another.",
"You have 2 questions there.\n1. Liquids flow faster than solids no matter where they are. The muscle that controls the exit from stomach to intestine doesn't slow liquids down much. Liquids exits your stomach fast but food can take several hours. Your body can't absorb a piece of pizza without breaking it down into tiny pieces and that takes time."
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2r5hsh | why isn't junk food good for bodybuilding? | Basically from what I know, junk food has lots of calories and calories seem to be what bodybuilders need in order to get big. But most bodybuilders recommend a healthy diet to get calories rather than gorging on oreos all day. | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2r5hsh/eli5_why_isnt_junk_food_good_for_bodybuilding/ | {
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"Depends on your philosophy. A lot of bodybuilders will do what's called \"dirty bulking\" which usually entails getting a lot of calories from junk food. Just because a lot of these guys are consuming 4000+ calories per day, and you can only eat so much chicken, rice, and broccoli. And some subscribe to an idea called IIFYM (If it fits your macros). Basically, that getting your carbs from brown rice or poptarts isn't relevant.\n\nHowever, junk foods don't have a lot of vitamins, minerals, or fiber, which are necessary for a well-functioning body. Also, many junk foods with high sugar content can cause high levels of insulin, a hormone that can promote fat retention.",
"The short answer is there are different *kinds* of calories. Some are good for building muscle, some aren't. Junkfood contains mostly calories that aren't.\n\nThe longer answer is you need mostly protein to build muscle, with some carbs to help and give you energy, and some fat so your body doesn't start cannibalizing your muscles for energy. The thing is, you need these in specific ratios. That's why bodybuilders don't just eat *anything*, they eat particular foods at particular times.\n\nBut why don't they eat junkfood at all? Because there are even more subsets of carbs and fats, and some of them are helpful to you and some of them aren't. Sugar is a carb, but it's not a carb that's as useful as grains. So even if a candy bar has carbs-- which I want-- the carbs are mostly \"bad\" carbs, so it's not really helping me.\n\nAnd now for some caveats:\n\nPeople can eat *some* of anything and be okay. When I say something is bad for you, what I mean is too much of it is bad for you-- and that's true of anything. But junkfood contains way, way more than a moderate amount of the bad stuff, if you eat it regularly. Moderation is key-- a bodybuilder can, and does, eat junkfood every once in a while.\n\nAlso, some bodybuilders do eat junkfood just because it has lots of calories. It's called dirty bulking, like someone else mentioned. The reason is it's easier or more efficient to eat foods that have a lot of bad stuff if they have a lot of good stuff too, then they get rid of the bad stuff later. What this looks like in practice is someone will eat three McDonald's cheeseburgers every meal, and get fat-- but also get strong. Then when they reach a certain weight, they'll regulate what they eat much more strictly and lose the fat, while still keeping the muscle."
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85n7k3 | why do humans have such a bad grasp of time? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/85n7k3/eli5_why_do_humans_have_such_a_bad_grasp_of_time/ | {
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"With our short life spans it's impossible to grasp the full extent of times length to one another. \n\nThink of it like 1% of a 10 year olds life is 1 year long, while 1% of a 70 year olds life is 7 years. Time perception is different from those two.\n\nNow with conscious writing only being around 2 or 3 thousand years, compared to the 60,000 years humans have collected and interacted a conscious thought.\nNow compare that to millions of years the earth has existed. To billions of years of the universe.\n\nThose small fragments make time a hard concept, as, ironically enough. It take time to understand time.",
"While we survived and grew as a species by being able to remember what didn't work from the past and plan for advancements in the future the main survival instinct has always kept us focused in the now. The now is there immediate danger is, where hunger and thirst are.\n\nThe need to survive moment to moment is the main line of perception with the others all supporting and guiding it. Information that is not useful is abandoned,and often that includes the when of an event, as only the how and what were really necessary.\n\nOf course this doesn't show up the same in all people, some have powerful concepts of time and others have nearly none."
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50h4lv | why does spell check not include many words? | I use google chrome(not sure if all spellchecks are the same). When I type responses in reddit, I'll normally get about 1-2 words that I use that are registered as misspelled. Then I type the word into google, and I'm re-assured that I spelled it correctly, and it is in fact a word. I have used Microsoft Word's spellcheck since about 2000. That version had more words than the current google chrome.
I cannot think for ANY plausible reason, as to WHY they have cut out it seems about 10% of the English language(other than some conspiracy theories about limiting language). What is a possible explanation for why google does not include much of the English language in its spellcheck for chrome? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/50h4lv/eli5_why_does_spell_check_not_include_many_words/ | {
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"The more words a spell check knows, the bigger the chance that you will accidentally type a acknowledged word, while trying to spell another word.. \n\n*Are you reddit for school?* wouldn't light up if the word reddit was on the list.. ",
"It's not Google that is neglecting to include words in the spell check dictionary, it's your operating system. Chrome [uses the platform spell checker](_URL_0_) as it's dictionary source. For example, if you're on Mac OS X, it will use the dictionary provided by Apple.\n\n**ELI5:** If the system spell check dictionary doesn't include the word gullible, Chrome won't know the word either."
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4dji7z | north carolina's hb2 bill | [deleted] | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/4dji7z/eli5_north_carolinas_hb2_bill/ | {
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"House Bill 2, the Public Facilities Privacy & Security Act, puts in place a statewide policy that bans individuals from using public bathrooms that do not correspond to their biological sex. The bill also reserves the right to pass nondiscrimination legislation to the state government, saying state laws preempt any local ordinances.\n\nIf you have a question, it would be good to put that in your request."
]
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5uc50m | how do all animals know that a ball is a play thing? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/5uc50m/eli5_how_do_all_animals_know_that_a_ball_is_a/ | {
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"It's less of \"This ball is a toy\" and more of \"this rolling thing is entertaining.\" Most animals need some form of entertainment, and a rolling object is very helpful in that. Humans aren't really any different. We roll things around all the time and entertain ourselves with things that are necessarily play things. ",
"Many animals have a chase instinct. If they see something prey sized moving quickly, they chase ofter it because a part of them wants to murder and eat it.\n\nBeyond that, animals like to explore their environment...particular pets who don't have to worry about survival and have a lot of free time on their hands. Balls are easy to interact with and can move in unexpected directions, providing the animal with stimulation and entertainment.",
"This is a pretty loaded question. I can put a ball in my snake enclosure to zero effect, for example.",
"I've seen a cat play with a walnut pit by batting it and chasing it repeatedly. Humans were not involved with providing it or initially setting it in motion; the cat designated a natural object to be a ball and invented the game on its own.",
"Critters like to chase things. \n\nAnimals that hunt really like to chase things. It is kinda what they did for millions of years. "
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448aio | during the last ice age, since the water had to come from somewhere, how much lower were the ocean levels and what affect on maps and human activity would that have had? | During the last Ice Age, Glaciers covered approx. 32% of the land area compared to today's roughly 10%. The water had to come from somewhere, but I can't seem to find any information on how much lower the oceans were and the effect on Land Masses. I've read that if the Antarctica Ice Sheet collapsed it would raise the sea by 200ft, but it seems to me the glaciers covering Europe and North America would have been huge in relation and would have lowered the ocean levels by at least hundreds of feet. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/448aio/eli5_during_the_last_ice_age_since_the_water_had/ | {
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"For one thing, there was a land bridge between Siberia and Alaska. That had some fairly important repurcussions for humanity.",
"[Here's a projection of the world's land masses during the peak of the last Ice Age](_URL_0_).\n\nAs you can see: no Great Lakes yet as they were covered in glaciers at the time. Anatolia is connected to Greece, Alaska to Asia, Asia to Indonesia, and America to Greenland. The Sea of Azov, The North Sea, The Baltic Sea, The Adriatic Sea and the Persian Gulf don't exist, while the Black Sea, Red Sea and the Sea of Japan are essentially lakes",
"Sea levels were 600 - 800 feet lower. The difference was not the same all over. In the north, the areas covered by glaciers were pushed down by the weight of ice and have since rebounded once the weight was taken off.\n\nIf you look at maps of undersea areas you can see river banks and deltas deep under water where it used to be dry land. The same rivers we have today but you can see where they used to run through dry land, that is now ocean.\n\nThe British Isles were once part of the continent until sea levels rose and flooded out the English Channel 10,000 years ago (more or less).",
"It has long been held that the ice age conditions caused a land bridge between Siberia and Alaska that the ancestors of Native Americans migrated over.\n\nAbout 40,000 years ago, the Austral-Melanesians spread out from southeast Asia to colonize Indonesia, The Philippines, New Guinea, Australia, etc.\n\nThey were a remarkable people, the techno-gods of their day. They had simple boats some 20,000 years BEFORE anyone else is known to have had them. Their ocean migration was significantly simplified by the fact that ocean levels were much lower in those days due to ice age conditions, so the longest stretch of open ocean they ever had to cross was probably no wider than about 80 km. Still, it was an impressive achievement for the time.\n",
"you should read \"fingerprints of the gods\" and \"the underworld\" by graham hancock. he runs with the fact that water levels were so much lower, and since we tend to live near the shores, there are likely many \"lost civilizations\" across the world in those strips of land that were lost as the water level rose."
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bx4i0k | if the melting temperature of hydrogen is -259°c and the melting temperature of oxygen is -218°c then why is the melting temperature of water (h2o) 0°c? | Shouldn't it be around -245°C? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/bx4i0k/eli5_if_the_melting_temperature_of_hydrogen_is/ | {
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"You can't just average the melting point like that. There are many different things that influence melting point, such as the composition of whatever you're melting (the closer you pack atoms together, the higher the melting point will be), and how the atoms are bonded together. That's why even a relatively small change can change the melting point drastically.",
"This may be explaining it a bit too simply, so I invite anyone to give a better detailed answer. But the reason is because you aren’t averaging out the properties of the two chemicals. You are adding the two to make an entirely new substance with its own properties.",
"Hydrogen (H2) and Oxygen (O2) are very small and symmetrical molecules. Two hydrogen mopecules aren't attracted to each other very much. The more attraction, the higher the melting point. \n\nFor attraction to happen you need different charges. The hydrogen molecule itself has no charge. The cores of the atoms are positively charged, the hull is negatively charged. The exact distribution of the charge within the hull varies slightly, so one side might be a bit more negative than the other. This little bit of variance creates a little bit of attraction hence the melting point being -259 and not e.g. -270. Oxygen molecules are a bit bigger, so there is more room for variation, so it's melting point is a bit higher.\n\nWater (H2O) is not symmetrical. The oxygen atom has a very positively charged core, much more so than either of the hydrogen atoms. So the negative charge in the hull (the electrons they share to form the bond) gathers closer to the oxygen atom rather than the hydrogen cores. The two hydrogen atoms don't attach opposite of another but at an angle of ~120°. So the side of the molecule where the apex of that angle is (the side of the oxygen atom) is significantly more negative than the side with the hydrogen atoms.\n\nThis difference makes the negative oxygen side attract to the positive hydrogen side of the next molecule over. And vice versa. Big attraction means high melting point."
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5we9gb | how do we "see" our memories? | When you close your eyes and picture a beach and you can sort of see the beach in black and white and it seems to be underlying your current vision - how does that work? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/5we9gb/eli5_how_do_we_see_our_memories/ | {
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"Your memories are in black and white? ",
"Hmm this is facinating already. I see my memories in colors. Same when I mentally picture or visualize imagined/self-created landscape, imagery or scenarios in my head. I'm also able to do this outside my \"eye range\". I can distance my own being from the equation completely and project myself into an imagined world outside my field of vision, even with my eyes open. \n \nI actually very often seem detached and \"gone/non-present\" in real life situations (told by friends and coworkers) because I excessively daydream and run hypothetical imaginary scenarios in my head. \n \nThis makes me wonder if every person has a unique experience with memory, dreams and imagination. I always thought this was a universal experience mostly tied to genetic limitations. \n \nI wish I could elaborate this further but english isn't my native language and I feel as if I can't describe this better due to the complexity."
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2w3llv | why do things stick together when they're wet? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2w3llv/eli5_why_do_things_stick_together_when_theyre_wet/ | {
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"This is caused by Surface Tension. The strong Surface Tension of water creates a sticky effect. ",
"Hydrogen bond, Baby Hydrogen bond, Baby Hydrogen bond, Bab Hydrogen bond, BabyHydrogen bond, BabyHydroHydrogen bond, Babygen bond, BabyHydrogen bond, Baby Hydrogen bond, BabHydrogen bond, Babyy"
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47x3zc | hegelian dialectics | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/47x3zc/eli5_hegelian_dialectics/ | {
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"You really can't simplify Hegel, but I'll give you my best try. It's going to be more like an ELI18. I'll also preface this by saying that my understanding of Hegel is dependent upon Marx and Feuerbach's critiques, as I have read very little of Hegel himself. \n\nHistory is a force that is best viewed as a Spirit. This Spirit is directed by a Supreme Idea, or **kind of like** a certain knowledge orientation towards the world of objects and the senses known by God. This Supreme Idea is at any given point throughout the unfolding of history the product of all the thing-objects as they are viewed by thinking-subjects and directed by their actions. (This is true at the level of statecraft, as well.) \n\nYou have likely heard of the thesis, antithesis, synthesis model of thought, which is an essentially decontextualized simplification of Hegelian dialecticism. Hegel actually uses abstract, negative, and concrete as a way to explain Spirit of history.\n\n I'm jumping over a lot of his work on phenomenology, but essentially the Spirit of History, if you were to pull apart a moment (or event) in history, is a \"substance\" or concrete \"object\" (though not necessarily a literal object) that is created by two \"forces\" whose relationship between themselves is fundamentally antagonistic, but in existing in such a relationship they \"magically\" create a \"compromise\" that is the actual object we can point to and say as an event within the unfolding of the Spirit. The Absolute Idea is this magical force that creates the concrete evidence of the Spirit. \n\nTo put it another way, think about a math equation: \n\nAssume there is an object x and its opposite -x. (And these objects are a \"thesis\" or \"abstract\" or positive idea and its critical \"negation\" or \"antithesis\"). \n\nThere is a function G such that x and -x yield event ∆. \nf(G) x, -x ---- > ∆\n\nNow how this function works is dependent on the Absolute Idea, and that is contingent with history. Different political and epistemic forces contend amongst each other for supremacy. But only through Hegel's system of logic can the Absolute Idea be understood from an objective perspective. \n\nDoes this make sense? \n\n----\n\nI'll stop here because I'm not sure if I've done any good in explaining Hegelanism. And I've also sort of corrupted Hegel's system in reducing it so much. But ask questions for clarification. A Socratic Dialogue makes understanding a bit easier. "
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5m1pi5 | how does internet speed affect online gaming experience | Been online gaming for years, but never really understood what , ping, upload and download really mean, and how it affects online. Currently, on speedtest, my ping is 15, download 37.18 Mbps, and upload 9.04 Mbps. How do each these numbers affect online gaming, mainly CoD, which is the most influential number. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/5m1pi5/eli5_how_does_internet_speed_affect_online_gaming/ | {
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"Ping is the time it takes a signal to go from your location, to the destination and back. For example, a \"ping\" to a spaceship on Mars would take several minutes because electronic signals cannot travel faster than the speed of light. Similarly, while the distance between the United States and China is negligible for the speed of light, it still requires time and is not instant. Additionally, at every node/server, there may be some computation or process to occur that redirects your signal to the proper location (which also may take time).\n\nDownload speed is the amount of information you can download from another. For example, downloading a game/music to your harddrive.\n\nUpload speed is the amount of information you can transfer to another. Have a high upload speed means you can upload a video to youtube much quicker.\n\nFor the purposes of COD, download speed is the most important item but once it is over a certain threshold, your hardware, and the server's hardware will limit you. ",
"Ping - how long it takes info to get from your computer, to the server, and back. This is pretty important in a video games as it determines how long it takes for things to happen and show up on your screen, and also for your actions to be received by the server. \n\nDownload speed - how much info you can receive per second\n\nUpload - How much info you can send per second. \n\nGaming doesn't actually require a lot of download or upload. Most of the work is done on your own computer, while the info sent to and from the server is as small and succinct as possible. ",
"Long story short, bandwidth gets you fast downloads, low latency gets you fast gaming, and packet loss hurts both. Bandwidth is a limit of the network capacity, and data caps placed on your account by your network provider so that you get the speed you paid for but no more. Latency is a matter of the switching performance of the switches and routers, the number of network hops the packet makes, and the distance between your computer and the other end of the connection. And packet loss hurts both latency (due to re transmitted packets) and bandwidth and is mostly a result of un optimized network routing and equipment defects.\n\nDetails: \n\n\n\n\nSo there are several different types of data and each has different sensitivities to network issues. For instance downloading a file is asynchronous and it is okay for parts of it to arrive out of order or for there to be a lot of latency in the communication because it's the size of the packets, and the number of them that make it through without being discarded that affects how quickly a download can work. \n\nContrast that with a skype call which doesn't use a lot of bandwidth, but the data that is sent, is time critical. If the packets arrive out of order it doesn't do you any good because by the time the system re-assembles them you've already moved on to the next sentence. We perceive these problems as jitter and sound dropping out or becoming noisy. So latency is somewhat important, not dropping packets is very important, and bandwidth is less important. \n\nThen you have gaming, where you and all of the people playing as well as the server all have to exchange packets quickly so that each user is updated on what the other users did for each slice of time, and the server calculates all of these, and then sends the results out to each client. For instance you shoot an enemy at the same time they shoot you, whichever packet makes it to the server first, that player gets the kill and the other doesn't. Then the server sends the results. So you might see you fire first, but if the server doesn't, then it doesn't matter. So the latency, or round trip time it takes a packet to be sent and responded to, is the most important. \n\nSo what effects latency, bandwidth, and packet loss? \n\nLatency is affected mostly by how far away you are from the server, and how many hops the packet has to make along the way. Packets are switched and routed, and each time they hit a switch or router, they have to be copied and re-transmitted and this causes a slight delay in the round trip time. This is less about the amount of bandwidth, and more about the switching speed and performance of the switches and routers. \n\nBandwidth is affected mostly by network traffic, and throttling such as paying for 500mbps internet, the cable company caps your bandwidth at this limit. Also if neighbors are downloading a lot of stuff and the cable network gets overloaded, it can slow down your speed for a bit. \n\nPacket loss and arriving out of order, is mostly a matter of provisioning the networking equipment to use the best route, not to exceed the packet size, your computer not using a packet size too large so it's not fragmented, and the quality of the connections between the different hops on the way to the other side of the connection. Line noise, thunder storms, corroded wires, radio interference, over worked equipment, and of course [the fiber seeking backhoe](_URL_0_). All of these lead to packets being lost or corrupted. \n\nAlso certain transfer protocols like UDP do NOT re transmit packets. If a packet is lost, it's lost. ",
"Ping time is most often very important to playing on-line games like CoD. This is the most important number and needs to be as low as possible. See other comments for what determines ping times. \nDownload/upload can be a determining factor in playing but if you have any kind of decent connection, not usually an issue. Most games are written to use as little as this as possible but that doesn't mean speeds can't affect your playing experience. If you are downloading something while playing, or other devices (family/friends) are on your connection watching vids, etc, this may 'use up' your download (and maybe even your upload) connection enough to impact gaming. \nPing times most important, download next, upload last. FYI: Ping time of 15ms is good.\n\n\"Will the values change on a speedtest the more users on streaming. For example, watching sky sports via wifi, kids on you tube, and download dropped to 18.9.\" Yes the values will change on speedtest the more users on it but if you are still getting 18 with others users, you still have way more download speed than you need for the game. I do not know what CoD requires for speed but I would guess in the range of 1-2. This is just a guess tho.",
"I like to explain it like a multi-lane motorway/freeway.\n\nBandwidth is like having more lanes. More lanes, more traffic. You can get more vehicles moving at the same time. Similarly, the more bandwidth you have, the more data you can download at the same time. Instead of one lane and one car at a time (say 56.6kbps), you can have several hundred (e.g. 50Mbps) cars simultaneously. Therefore more data can be transmitted. It's also harder to clog up, so somebody streaming videos, music and playing games is less likely to cause a traffic jam on a high bandwidth connection.\n\nLatency/ping is like the speed and distance at which the traffic travels. It's the time it takes for something to transmit from your computer to another and then back again. So imagine it like cars going on a return journey. Cars going faster will get there and back sooner. Consequently, you could have a low-bandwidth connection, with a lower latency/ping than a high-bandwidth connection, like having a single-lane road, 10 miles long, with a speed limit of 200MPH and a 20 mile long, 200-lane road with a speed limit of 2MPH.\n\nAlso, there's the idea of data being transmitted as packets. Depending on the stability of your connection, packets can be lost, which can result in some data never being transmitted. If you have an unstable connection, it could be why you shot a guy 200 times in the head, but they then turned around and instagibbed you.\n\nGames do require a certain amount of bandwidth though, although it isn't as much as people think. It's why we could play online games pretty happily in the late 90s and early 00s with dial up connections. There is a certain sweet spot between bandwidth and latency, and that changes with the times. I don't remember the exact figures, but I remember tracking how much bandwidth video games like Destiny (a supposedly data intensive game) used per hour and it ended up being something like 150-200MB per hour on my Xbox One, or something like that. YMMV if you're using things like VOIP too. Anyway, you will often see people state stuff like 900GB/minute, but that's usually because they're totally ignoring other forms of data usage in their homes or ignoring that they have 50 porn torrents open. Technically, a 768k/256k down/up should just be enough for a lot of modern games, so long as you do not do anything else at the same time. In terms of bandwidth, anyway.\n\nAnother caveat is that high-bandwidth connections have a tendency to use better lines and consequently lower latency. So there is generally some correlation with high-bandwidth connections also having low latency (like using fibre optic cables), which is a part of the reason people often conflate high-bandwidth with low latency.\n\nSo, for gaming. You ideally want a connection that meets minimum bandwidth, has a low latency and is stable (no packet loss). IF you don't have those three things, you will not have a good time"
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2rmb1n | why are you not a blood donor? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2rmb1n/eli5_why_are_you_not_a_blood_donor/ | {
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"I've did it once afew months back, and I want to do it again, I'm just not regular yet",
"Because even though HIV can be contracted by any human, regardless of sexual orientation, you're not allowed to donate blood if you have EVER, as a man, had sexual contact with another man.\n\nAny other self righteous questions? ",
"Auto immune disease. I do really appreciate people who have donated though, has helped me out a few times. ",
"Because I don't weight enough to be eligible. ",
"Easy answer: because I have anemia. \n\nHard answer: Even if I didn't, I still wouldn't donate blood. A few of my personal reasons:\n\nThe blood banks are not open on weekends, I have to work during the week.\n\nThe nearest blood bank is about an hour away.\n\nI am afraid of needles/doctors.\n\nWhen they take my blood samples my arm always gets painful, bruised and bleeds afterwards. I get light headed. \n\nI'm a selfish human being."
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34h9ku | why do tv shows sometimes have cast that are "featuring" or "with," and included as part of the main cast? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/34h9ku/eli5_why_do_tv_shows_sometimes_have_cast_that_are/ | {
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"It's called last billing.\n\nSo, if you are a top actor, you want to be first in the credits. Credit order (billing) is a big deal for actors, and their billing is part of the negotiation with the studio \n\nBut if you can't be first, you don't want to be second -- you want to be last. A last billing with a word like \"featuring\" or \"and John Smith as Dr. Schmoo\" is better than being lost in the middle of the credits. ",
"In addition to /u/Teekno's great response, last billing is often used when an older, more established actor takes on a non-leading role.\n\nIt is important for both the show and the actor to give the impression they are more than just an ordinary cast member. Rich and famous Danny DeVito working on a small project he finds interesting artistically is a good story. Broke and pathetic Danny DeVito schlepping for a paycheck on basic cable is a downer. Giving him special mention lets viewers know which one it is."
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7x14fq | why must countries borrow from the world bank but not banks with lower interest rate? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/7x14fq/eli5_why_must_countries_borrow_from_the_world/ | {
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"Simply put the World Bank will loan money without considering the risk of default. Commercial banks insist on being paid back. They will not loan to some countries.",
"First, the amount of money may exceed the bank's abilities. My local bank couldn't loan me 80 billion dollars. Even the world largest banks sometimes have trouble providing the level of liquid capital (i.e. cash) to a nation, given the size and scale. \n\nSecond, sometimes the banks don't trust the country. The world has a fairly recent history of countries defaulting or nearly defaulting on their debts. That level of uncertainty is bad for business. I loan you 100billion and I might get back 140billion, I might get back 70billion, or you might declare me an enemy of the state and give me the shaft. Lots of banks have divested/given-up on bond purchases and large loans to developing nations, or those with a history of debt repayment issues. It's to this end that the World Bank is supposed to function, as a sometimes \"bank of last resort\" for countries. ",
"It's not the case that countries **must** borrow from the World bank. Most would prefer to borrow from banks or sell bonds (as the US does). When nobody will buy their bonds nor loan them money, a country can still go the World Bank for money. It's the lender of last resort, but some countries are not very safe investments."
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ba6utg | are blue light glasses a scam? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/ba6utg/eli5_are_blue_light_glasses_a_scam/ | {
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"No, it's basically the same as red-shifting your displays. If your phone supports (or have an app) that red-shifts your displays, use it especially in the dark, your eyes are much less strained.\n\n"
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2a72u5 | how is the "1 in 35 million chance of a shark bite" statistic calculated? | Or any such statistic (e.g. You have a 1 in 1 million chance of being struck by lightning, etc.) for that matter.
My friend asked me this a couple of weeks ago. The only reasonable explanation I could think of was that they take the total number of bite victims compared to the estimated number of swimmers in waters where sharks frequent.
Edit: It seems I was more or less correct. Number of incidents / total number of people exposed to situation that could lead to said incident = chance of said incident happening to any given person.
_URL_0_ | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2a72u5/eli5_how_is_the_1_in_35_million_chance_of_a_shark/ | {
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"I'm no mathemagician, but I think it has something to do with the total world's population, the number of shark attacks per year, and the total number of individuals attacked by sharks.",
"I think it's actually done by population. There is a nice freakonomics article here: _URL_0_\n",
"It is based on beach attendance. [The university of Florida has some statistics that get you to a 1 in 11.5 million chance of being attacked by a shark](_URL_0_). \n\nEstimated attendance at US beaches is ~264 million. The number of shark attacks is 23. 264 million divided by 23 give you 11.5 million. That is, for every 11.5 million beach visitors, one was attacked by a shark in the year 2000. ",
"I will state up front that I am not an expert in this. However, I have taken post-graduate probability and statistics. And looking at this on the surface, there are a couple of possibilities:\n\n#1) Survey a random sample of people.\n\nNow, the obvious problem here is that with the odds calculated, the sample size for such a poll would have to ridiculous. So, for practical purposes that rules this out.\n\n#2) Calculate a contingent probability.\n\nBased on #1, it would make more sense to do a simple poll of a random sample of people to determine how many people have been to a beach in their lifetime. The random sample of people should provide a good benchmark for the proportion of population that goes to the beach. Then, in addition, you need some beach metrics for average attendance per year. This will allow you to extrapolate the average number of beach visits per beachgoer. Finally, take the number of shark attacks and calculate a simple probability...\n\nWhat is the probability of a random beach-goer being attacked by a shark in a single beach visit? P{Attack | Visit}\n\nWith that answer...and the information for average number of visits per beachgoer, you can calculate the probability that an average person will not be attacked in any visit. The probability of attack is 1 minus that.\n\nLike I said, I'm not an expert. Statisticians might have a much simpler method than that, but that's how I would set up the math problem to get the information based on statistics that are readily available.",
"They made a guy swim into the ocean a bunch of times until he got eaten."
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seauu | big o, theta, and omega | Lots of ELI5 about Big O, but none really about theta/omega, that I could find.
I would like these from a computer science point of view, but if their is anything you know, that'd work too.
If someone can explain these, the differences, why use each, and what they really mean, I'd appreciate it. | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/seauu/big_o_theta_and_omega/ | {
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"Theta and omega explain the same thing as Big O.\n\nYou can think of big omega as the \"opposite\" of Big O. It says that one function grows slower or equal to another function. This isn't actually correct (see my end note), but it is conceptually how you can think of it.\n\nBig theta can be thought of as a combination of Big O and Big Omega, in other words the functions are on the same order.\n\nNote that these are actually sets. Saying f(x)=O(g(x)) doesn't really make sense. The proper way is to say f(x) ∈ O(g(x)).",
"Lets say you have a function f(x) and it runs at a speed of O(x^2) - just for an example. (Most commonly a nested for loop makes an x^2 running time)\n\nThink of **Big O** as the highest \"bar\" that some function f(x) can get to (Or the worst-case running time for lack of a better description). So if you were to calculate the \"actual\" runtime of the function f(x) and it turns out to be something like x^2 + x + 1 (just for an example) the most significant expression is x^2 and it is SO big that it makes all the other expressions not important. So it gets simplified to O(x^2). This is the **asymptotic upper bound**\n\nNow, since Big O just deals with the highest \"bound\" of the function, we need other ways to describe the function. What about the \"best-case scenario\"? That is what **Big Omega** is. If everything goes \"right\", you get the Big Omega runtime. This could mean that you find what you are looking for in the first try in the nested for loop example so it doesn't have to go through the entire list. This is the **asymptotic lower bound**\n\n**Keep in mind that Big O and Big Omega can be the same.**\n\n**Big Theta** is a bit different. The Big Theta of your function f(x) is bounded between Big 0 (\"Upper\") and Big Omega (\"Lower\"). I'm going to throw an equation at you but I'll describe it.\n\nf(x) is Big Theta of g(x) if and only if (f(x) ∈ O(g(x)) and (f(x) ∈ Ω(g(x))\n\nThis reads out as:\n\n\"f(x) is Big Theta of g(x) if and only if f(x) is Big O of g(x) **AND** f(x) is **ALSO** Big Omega of g(x)\"\n\nThis means that f(x) is bounded on both sides by g(x). This makes Big Theta a stronger measure as it gives both measures and not just one.\n\n[Edit] for typos",
"This is not a topic for ELI5...",
"Big O means an algorithm runs at least this faster, it might run faster.\n\nBig Omega means an algorithm runs at least this slow, it might run slower.\n\nBig Theta means an algortihm runs *exactly* this fast.\n\nMost the time when people talk about Big O, it would be more precise to use Big Theta."
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4kwl4h | why are most wwii photos in black in white since color photography has been around since the 1800s? | I'm assuming because it was a lot more expensive back then but I would have guessed that WWII would have been more of a priority for this type of thing. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/4kwl4h/eli5_why_are_most_wwii_photos_in_black_in_white/ | {
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"On top of being more expensive, you needed a much longer exposure to get a decent picture with color than with black and white. Standing still for an extended period of time in a war zone is a great way to get killed. ",
"Methods of making color images existed in the 1800s, but they were more like taking three separate black and white photos through coloured filters and then combining the resulting images later, hoping that your subject didn't move between the three images. Colour film as we'd recognise it only came along in 1935, so it was still very new in WWII.",
"This is a concept I like to mention to people when a question like this comes up. It's not when a technology is **invented** that's important, it's when it's **affordable** and **easily available**.",
"It existed, but it was difficult to use (exposures had to be *much* longer) and prohibitively expensive, so it wasn't used much.",
"Basically color photography sucked up until the 1970s. Modern color film techniques basically started in the 1930s. But the processes involved were not only expensive, but a major pain requiring a lot of special processes. \n\nIn the 40s it got a little easier with more convenient film and prints, but it was still expensive and the film was still pretty slow. Slow film requires wither a longer exposure or a lot more light. This allowed some professionals to use the technology, but for the most part it was outside the reach of most people. It wasn't until the 1970s that color photography took off. This was due to a combination of faster film, cheaper film and processing costs, and the invention of electronic flashes; which are reusable as compared to the one shot flash bulbs they used to use. \n\nAlso being a somewhat new technology during WWII, not a lot of faith was put into it. A war photographer would shy away from using it mainly because you wouldn't know what you'd get. In fact, you'd notice that a lot of photojournalism, particularly in places where sane people wouldn't want to be like a battlefield, up until very recently was also in black and white. This is because black and white photography is simple all around. A person can develop black and white film in the field much easier than color film. By developing the film, you make it stable for transport. Not having to worry about accidentally exposing your once of a lifetime shots on your travels until you can get to a color film processing lab. In fact, most of the color film used during WWII was Kodak's Kodachrome. Kodachrome at that time had to be sent to Kodak to be developed because the process of doing so was so complicated and proprietary. ",
"Black and white was actually used well into the 1980's for a lot of historical events. A lot of this photography was for newspapers. Newspapers didn't print in colour, so photographers shot in black and white."
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160eko | the news recently that scientists have achieved a temperature below absolute zero in the lab | I've read the articles but I still have trouble understanding this..
An article, if curious: _URL_0_ | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/160eko/eli5_the_news_recently_that_scientists_have/ | {
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"I get it, but I don't. It's weird. I'd be really interested in it if it was explained a little differently I think.\n\nI don't really get the paragraph that starts with the \"Physicist Ulrich Schneider at the Ludwig Maximilians University of Munich set out to do something unusual\"... Perhaps because I sucked a physics and chemistry. So yeah, I'm up for trying to understand it!",
" > A negative kelvin temperature indicates that particles at high energies outnumber those at low energies.\n\nIt just means this.\n\nThis article is about a very, very technical use of the word \"temperature\", not about temperature in the usual sense.\n\nHere are the parts of the article that summarize it best:\n\n > Physicist Ulrich Schneider at the Ludwig Maximilians University of Munich set out to do something unusual: He wanted to cajole the particles within a substance to be confined to a very high amount of energy. In other words, instead of having the particles start at a minimum energy (corresponding to absolute zero) and spreading out toward higher energies, he wanted to start at a maximum energy and spread toward lower energies. By definition, such a substance would have a negative kelvin temperature.\n\n > This temperature is technically not below absolute zero, because negative on the kelvin scale (unlike that on the Fahrenheit or Celsius scale) is a construct that simply indicates something about the energy state of the particles involved. In fact, the new creation is extremely hot because of the high energies of the particles. Heat travels from hot to cold, Schneider says, and heat will always flow away from this gas. “It’s actually hotter than everything we know,” he says.\n\nOnce again, this is about a kind of technical quantum mechanics thing, so it's hard to explain exactly what they mean in terms of every day activities.",
"It's not possible to get to absolute zero, let alone to go below. ",
"To start, we need to define a few things--specifically, heat, entropy, and temperature. \n1) Heat is a type of energy that is transferred between objects based on a difference in temperature. It is symbolized by the letter Q. But this gives rise to the question, what is temperature?\n2) Temperature is traditionally defined as a measure of the kinetic energy (energy of motion) of the particles in the system. It is represented by T.\n3) Entropy is much harder to explain conceptually, but it has to do with the \"disorder\" of the system, and how many possible states that each particle can be in. It is represented by the letter S.\n\nNow normally, the definition of entropy can be given by dS=dQ/T. (If you're not familiar with calculus, just consider the d to mean a small change, so a small change in entropy is equal to a small change in heat divided by the temperature at which this process occurs.) However, we can also reverse this to say that T = dQ/dS.\n\nIf something has a positive Kelvin temperature, that means that when heat is added to the system (dQ > 0), the entropy of the system is increased (dS > 0). BUT if we *define* temperature to be T=dQ/dS, then there can mathematically be a negative Kelvin temperature if heat being added to the system causes a *decrease* in entropy. And this, to my understanding, is what has been discovered--a state in which the energy is so high, that when more energy (heat) is added, the disorder actually decreases. Note that in this case, temperature is **not** defined as proportional to kinetic energy, it is merely the change in heat over the change in entropy.",
"I don't think this article is true. In Physics, my teacher pounded absolute zero into our heads. Heat varies on how fast the particles in an object are moving. Absolute zero is when there is no moving, period. Not zero as in 0 degrees Celsius or Farenheit, but as in there is no heat PERIOD. (Remember, there is no such thing as cold, just an absence of heat) Technically, below absolute zero is impossible.",
"Lower than absolute zero is actually fairly misleading. \nThere are essentially two types of temperatures, positive and negative. \n\nLets imagine we have a group of three particles in a box, and each particle has two energy states, high and low. \n\nA system with positive temperature is a system that when we increase the energy of the system, the disorder (entropy) of the system also increases. \n\nIn our particles in a box example, imagine all three particles are at low energy initially. We add enough energy to bump a single particle to a higher energy state. We no longer can say for certain which particles have high or low energy, only that 2/3's have low energy, thus the system is more disordered (entropy has increased). \n\nOn the other hand, a system with negative temperature is one where the disorder of the system decreases when we increase the energy. Back to particles in a box... \n\nWe now have 2 particles at high energy and 1 at low energy. We add energy so all three particles are at high energy. The disorder (entropy) of the system has decreased (we know the state of all particles). \n\nNow, generally we have a pretty uncountable number of particles in a system, each of which has far far more than two energy states. This means that the second situation I described isn't very physically likely to occur, so we have to do crazy things like use lasers to limit the number of states the particles can occupy to actually find systems with negative temperature. \n\nFinally look at the example on the right [here](_URL_0_). The first graph is entropy (disorder) vs energy. The spot where the parabola switches direction is on approaches positive infinite temperature on the left, and negative infinite temperature on the right (See graph #3). \n\nThis is actually because the more fundamental thermodynamic constant is the inverse of temperature Beta = 1/kT (k is the boltzman constant). Beta (pictured in graph two) goes from +inf to - inf continuously. Because we actually look at the inverse of Beta, we see that odd switch from -inf temperature to + inf temperature. \n\nHopefully this cleared some stuff up because I wasn't really happy with the other answers here. Might have lost you in the last few paragraphs, but honestly the first few are more important. \n\nsource: [mostly this](_URL_1_)"
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36s7gb | can you cure strep throat by drinking enough alcohol? why or why not | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/36s7gb/eli5_can_you_cure_strep_throat_by_drinking_enough/ | {
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"Yes. Drink enough alcohol until you pass out and die. The bacterial that caused strep throat will also die. \n\nIf that cure is unacceptable then no. Because the bacteria that caused it won't be exposed to the alcohol long enough, or in high enough concentration to kill it.",
"Yes. Take a scalpel (or your sharpest knife) and cut out your throat's mucosa. Then soak it in alcohol for an hour or so. Then put it back in.\n\nIf that cure is unacceptable then no. Because the bacteria that caused it won't be exposed to the alcohol long enough, or in high enough concentration to kill it.\n",
"The bacteria causing strep throat (and most infections) live throughout the tissue that's infected. Applying any treatment topically is of limited use for most infections, because you're not penetrating through the entire infected zone.",
"Yes. Replace your entire blood supply with pure grain alcohol. After twenty minutes or so, Put the blood back in.\n\nIf that cure is unacceptable then no. Because the bacteria that caused it won't be exposed to the alcohol long enough, or in high enough concentration to kill it."
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3v4cir | australian and new zealand's role in the vietnam war | I'm writing this as a 15 year old Australian male, and I am wondering, if the Vietnam War was purely the U.S's war, and even Britain declined the US any troops, and the only reason Australia and New Zealand was in the war was because we had been previously in a treaty. Australia lost 534 soldiers, and had 3000 wounded, whereas the US lost 58000 soldiers. Up to 3534 Australians lost during a war that was not even ours seems to be very costly. Why did America do this? Did they just think they would win with the extra support? If Australia and New Zealand was to not provide troops, what would the repercussions be for the Australian and New Zealand people?
On another topic: (I am writing this for knowledge and not to be offensive at all). How come the US only entered the Second World War very late, AFTER they were attacked, whereas the British and their empire entered even when they were NOT under threat? Why are the US's Vietnam soldiers more decorated then their WWII soldiers? (In Australia at least it is literally ALL ANZAC soldiers (World war one and two that are celebrated)
Thank you for any answers. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/3v4cir/eli5_australian_and_new_zealands_role_in_the/ | {
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"In a nutshell, our (Australia & NZ) giving moral support to the US by fighting along side with them, ensures that by honouring the ANZUS alliance in concrete terms, we can rely on the US to protect us against Indonesia or any other enemy we couldn't handle alone that might threatens us in future. \n\nThis is why Australia for the foreseeable future will always be present in any armed conflict that the US invites us to and why we have US bases here, regardless how our public may dislike the idea.\n\nBy spending a relatively small amount of Australian blood from time to time, we ensure that Americans will be prepared to spend a lot of blood all at once to aid us. Because if we need their help our need will be truly dire.",
"About your other topic: how was the UK not under threat? An unbalanced continental Europe has historically always been a threat to UK interests and the rise of nazi Germany was definately something to be extremely wary of. A large and unchecked buildup of the Kriegsmarine in the North sea is also a direct threat to UK interests. \n\nThe formal reason the UK went to war was that the UK guaranteed the integrity of Poland. The invasion of Poland forced their hand: either back down or declare war on Germany, with France as a major ally.\n"
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20b1zg | can i declare war? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/20b1zg/can_i_declare_war/ | {
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"You could try, what are you going to do though? they would probably laugh and if they thought you to be a terrorist call the police/Interpol and you would be put on a no fly list ",
"They would probably limit your ability to travel to their country. And put you an a terrorist watch list. It might end up only extending to that country or the entire EU might put you on the watch list and make you endure long searches and waits when travelling.",
"Actually, by international agreement, NO, you cannot Declare War against a Sovereign State. Only another internationally recognized Sovereign State can Declare War against another, legally.",
"1,2,3,4 I declare a Thumb War!",
"Because your post isn't asking a simplified conceptual explanation, but rather for an answer, its been removed.\nYou should try /r/answers instead."
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bv4jyx | why do liquors that are made from carb-heavy foods like potatoes (vodka) and sugar cane (rum) have no digestible carbs in them? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/bv4jyx/eli5_why_do_liquors_that_are_made_from_carbheavy/ | {
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"The carbs are broken down into sugar and then into alcohol by the yeast. So all you're left with is a sweet alcoholic mess.",
"They have. Ethanol, drinking alcohol, gets metabolized to acetate, which is basically vinegar.\n\nAlcohol is actually quite rich in calories.\nCalorie content of pure alcohol is in between sugars (more) and fat (less)."
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n8vsp | how do cars float? | Cars can weigh up to thousands of kilograms. In movies they are always portrayed as sinking when they hit the water. I thought this was so in the real life too, but then I saw this [video footage](_URL_0_) of the recent Japanese tsunami where all the cars just float around.
Why do the cars not sink when the water rises? They're mostly just metal, and all metal objects I've thrown at the water have sank (because the density of the metal is greater than the density of the water, I guess). Forks and knives, for example.
Are there safety guidelines telling that cars should float? Is my action movie immersion ruined forever? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/n8vsp/eli5_how_do_cars_float/ | {
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"they eventually sink, first they massive air bubble in them(passenger compartment) has to be filled with water. secondly they're big and when the water is rushing it sometimes takes a few minutes for the current to allow them to settle. ",
"It's the same reason why much, much, much heavier ships float. (A [full supertanker](_URL_0_) can displace over 500,000 long tons)\n\nAir is very good at keeping things afloat and you don't need a lot of it to offset the weight of a car, because air is a lot less dense than water.",
"they eventually sink, first they massive air bubble in them(passenger compartment) has to be filled with water. secondly they're big and when the water is rushing it sometimes takes a few minutes for the current to allow them to settle. ",
"It's the same reason why much, much, much heavier ships float. (A [full supertanker](_URL_0_) can displace over 500,000 long tons)\n\nAir is very good at keeping things afloat and you don't need a lot of it to offset the weight of a car, because air is a lot less dense than water."
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9i4494 | how did computers store dates that led to the y2k problem | The usual explanation I've heard is that they only stored 2 digits to save space and this would lead to problems, but if you had stored them as characters that would be 1 byte per character and if you stored year as a single byte you'd have 256 years to worry about rollover.
Did they try to pack both digits into 1 byte?
3 bits you get you 0-7 so to pack 0-10 you'd need 4 bits, so you'd either save zero or maybe 1 bit doing it that way.
& #x200B;
How were years stored in a way that saved space? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/9i4494/eli5_how_did_computers_store_dates_that_led_to/ | {
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"The issue was a bit higher level than data types and storage and had to do with interpretation of date values. The whole \"2 digit years save space\" thing wasn't really that much of a thing. Most dates were stored in an epoch format - an integer representing the number of seconds that had elapsed since a predefined date (usually 1/1/1970 12:00AM) - so date values were the size of integers, programmatically speaking. \n\nHowever, dates were also sometimes stored as text, and/or program logic would calculate date differences or additions based on years being in the 20th century. Consequently, when a 2-digit year rolled over to \"00\", the question/concern would be that it would be calculated as 1900 and not 2000.\n\nLuckily, the problem turned out to be not as extensive as was feared.\n\nThat being said, Y2K-related projects built me a nice house, so it was incredibly necessary those projects happened to make absolutely sure. ;)",
"It was som kind of BCD(Binary-coded decimal) coding where the simple way is to only store on digit per byte or with packed BCD where used 4 bits per digit and store 2 digits in a byte.\n\nThat is for system with 8 bits in a byte and that was not a fixed to that value back then and you hade different byts size or word size as we often refer to it on older computer today. A back then common IBM 1401 used 6 bits for each character and a word stop bit and a parity bit. The variable word length and word stop bit is so you could add BCD coded number with different number of digits with one instruction. So the computer did not use the type of binary encoding that we used today most of the time and the language used was made for a computer like that.\n\n\nA lot of the problem code was in system was written om COBOL that from the early 1960 was common for business, finance, and administrative systems as it was designed for that. You specified length of a variable in digits in a format like \"YEAR PIC 9(02)\" where you hade two 0-9 digits. So it was fixed with numbers with base 10 and not directly a 8 bit integer like in other languages\n\nSo a date on that format with 2 digits for year,month and day for a total of 6 characters or 8 characters depending of year format \n\n\nIt was business system there is a lot of dates. Memory in computer back then was small and early core memory had a cost of $1 per bit ans that is in 1960s dollar. Monthly rental for 1401 configurations started at US$2,500 (worth about $20,987 today). IBM 1401 had a memory of 1400, 2000, 4000, 8000, 12000, or 16000 words of memory. The IBM 1401 was produced in 12 000 unit until 1971. In the mid 1960 nearly half of all computers in the world was a IBM 1401. So the code was developed in a completely other world the today computers.\n\nThe device you use to read this post have likely more memory the all IBM 1401 combined. If all had 16000 words the total memory was 1.5GB. I would guess the same for total CPU speed.\n\n\nSo for a 2000 word memory you could store 333 dates with 2 digits for year or 250 for with 4 digits. So not we can see that the the number of digits you use start to look important. So legacy code that started in a world like that when no one would have guessed that part of it would be in used 40 years late had a big problem,\n\n\n",
"It goes waaaaay back to first computers and the cost of storage. Programmers were always forced to looks for ways to save space, using abbreviations, because space was very costly and limited back in the 50's,60's and 70's.\n\nSo an easy way was to abbreviate the year from 4 digits (1962) to just two digits (62). Programmers then started using dates like 3/21/62 (March 3, 1962) in software and never updated something as silly as the date.\n\nSo, in the 90's, storage is cheaper, programmers are using 4 digit years for new software, but there was a lot of old software that required a 4 digit upgrade from 2 digits.\n\nWhen 1999 (99) rolled over to 2000 (00), it could also be interpreted as 1900 (00).\n\nThus the Y2K problem. \n\nI think it went smoothly, thanks to a lot of pre-planning and software/hardware upgrades before midnight, December 31, 1999"
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2yqg8r | how did africans survive in the past when they are dying of hunger today? | All these thousands of years, have they populated rapidly when they were suffering from hunger or is it something new? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2yqg8r/eli5_how_did_africans_survive_in_the_past_when/ | {
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"First of all, Africa is a [huge continent](_URL_0_) with much diversity in respect to how the societies live. Some parts have major problems with famine, most parts do not. It's not that \"Africans are dying of hunger\" but that \"a small minority of Africans are dying of hunger\". But by no means are the famines something that threaten the very existence of all African people. It's not like there's a huge one big famine in Africa, rather some different parts of Africa have famines in different times. But western media especially has this narrative of talking about just \"Africa\", giving us an impression of quite homogeneous place with similar conditions pretty much everywhere.\n\nSecondly, historically famines have happened from time to time throughout the world, not restricted to Africa. For example 150 years ago my native Finland had a famine killing 15% of the population. Ireland suffered a famine starting from 1845 and it killed a million people. Great Chinese Famine in 1958 - 1961 killed 15 million people. Famines have a wide array of causes, like natural causes in the case of Ireland (potato blight) and Finland (shitty weather and crop failures) or man made political turbulence and failures (China). Like these countries survived famines, so do African countries suffering from famine.\n\nRelatively recently industrial development has managed to cut famines in industrialized and industrializing countries almost completely. Africa is the least industrialized continent, so in some parts it still reflects the conditions rest of the world also has dealt with in the past. It also means several African nations are more sensitive to natural threats like extended drought. \n\nBecause famines are practically non-existent in industrialized countries, it is a stark contrast to industrialized countries when other countries have famines, and they are a focus of humanitarian efforts from the richer countries. We hear so much about famines in Africa because famines are so unusual to us, and we often have both governmental and non-governmental organizations informing us in order to raise help and awareness.",
"Among other reasons, political factions control the food supply to maintain control of that region or to punish the populace. That is, when there is food, the army takes it and/or won't allow aid to enter."
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2lnqu5 | why darker pee mean's our kidneys are unhealthy. wouldn't the darker liquid mean more is being filtered and taken out of the body? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2lnqu5/eli5_why_darker_pee_means_our_kidneys_are/ | {
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" > Wouldn't the darker liquid mean more is being filtered and taken out of the body?\n\nNo, it means that less water is being expelled, and is usually a sign of mild dehydration. When there's less water to work with, your kidneys have to work harder to expel the same amount of waste products. Remaining dehydrated for long periods of time can cause kidney damage."
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74a7mo | why does making a cringing face make pain feel less painful. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/74a7mo/eli5_why_does_making_a_cringing_face_make_pain/ | {
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"You are straining muscles to force a different bodily sensation so that instead of one focused area of nerves that send out \"pain\", there's also a lot of different nerves sending \"strained\" to compensate and mitigate the pain.\nYou probably also cringe or wince with your entire limb or body - but the face has quite a large number of muscles and more sensitive and denser nerves, so you experience its sensation more intensly."
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4343u0 | the cause of the challenger disaster. | I just don't understand the technical jargon. Something about an O-ring failing but what is an O-ring and what followed after it failed? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/4343u0/eli5_the_cause_of_the_challenger_disaster/ | {
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"The Solid Rocket Boosters (SRBs) - the two pointy rockets on the side of the big External Tank - had joints at the bottom so they could maneuver slightly as needed during launch and ascent. The joints were sealed with big rubber ring-shaped seals - the O-Rings. When the rubber was exposed to sub-zero temperatures for a long time it became brittle, less flexible.\n\nDuring launch the pressure on every part of the ship is, you can imagine, enormous. The O-Rings cracked (because they were so brittle as a result of the sub-zero temperature at launch) and burning fuel escaped from the side of one of the SRBs. It acted like a welder's torch and cut through the strut holding the SRB to the side of the External Tank. The SRBs were held on by two struts - one at the top, the other at the bottom. When the bottom strut was destroyed the SRB pivoted on the top strut, which sent the top of the SRB directly into External Tank. The ET was just as the name says: a giant tank, filled with enormously-explosive fuel under tremendous pressure. When the ET was ruptured the fuel expanded into a gas - the big round white cloud you see initially in the footage. The gas then ignited when it came in contact with the engines - the cloud turns into a fireball about a second later. These explosions shredded the Space Shuttle."
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dgq21o | how was the electron beam in crt televisions aimed and moved with such speed and pinpoint accuracy? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/dgq21o/eli5_how_was_the_electron_beam_in_crt_televisions/ | {
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"This is really interesting, actually. The timing was driven by the 60hz ac power supplied to the TV set itself (50hz in PAL countries). Analog circuitry took this timing and, in conjunction with the analog radio waves received, scanned lines and frames (called fields).",
"Focusing on how the speed and accuracy was attained instead of the technical how its done ( can answer that if wanted) Like most innovation there is considerable time and effort from the first version to what we see today (Less so considering the decline of CRT now). The first CRT had rounded display corners as it was not very accurate in these locations, the deflection coil (electromagnet that targets the beam) had trouble getting accuracy in the corners due to it needing the most deflection angle from its default path. The speed aspect is also relative, for us it seems fast but for electronics its rather slow compared to what the attainable limits are.\n\nTo summarise: the accuracy increased with minor improvements in design, manufacturing process and component quality over time. The speed of the process only recently (generally speaking) started to increase (refresh hz) by doubling the original 50 or 60z or using digital timers to drive the FBT (fly back transformer) speed.\n\nCheers",
"The beam was deflected using 4 electromagnets in the CRT. If you notice on a CRT it blooms out a lot before filling the entries screen; that is where the coils are placed\n\nBecause electrons have a very defined charge, we can manipulate them with the electric and magnetic fields to deflect them exactly where we want in a very consistent manner."
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4naosc | what's the point in having a strong password if most passwords are stolen from the server end rather than from brute force hacking a single account? | Your password must be at least 8 characters, with a number, uppercase letter, and special character. Then their server gets hacked and 30 million passwords are stolen. So why bother?
Are the passwords encrypted within their server and a complex password makes it harder to retrieve from the stolen passwords? Either way I don't get it.. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/4naosc/eli5_whats_the_point_in_having_a_strong_password/ | {
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"Passwords are not supposed to be stored on servers in clear text. They are usually stored after a one-way hash is applied so if a table of them is stolen the original password cannot be retrieved. ",
"If the passwords are properly stored, they'll be hashed. This means that your password itself isn't stored, but only the result of a calculation that's based on your password. Strong algorithms aren't reversible, so when someone has the database the only way for them to find out what the password is, is to guess a password, calculate its hash, and see if the hash matches. (The website should also use a \"salt\", a random value unique for each user, to calculate the hash--this means that two users with the same password will have different hashes, and hashes from some other cracking attempt can't be used.)\n\nStrong passwords are harder to guess in this way. Even if you can guess thousands of passwords per second, it will take an extremely long time on average to guess something like a 15-character random string. This provides time for the breach to be uncovered and then for you to change the password.\n\nNote here that you should still assume your password is compromised. A cracker could get lucky, or the website could have used bad algorithms for the hashes that are easy to crack. This is why it's very important not to reuse passwords between websites. On the other hand, no matter how many precautions the website takes with password storage, they will all fail if your password is easy to guess.",
"A few of the other posters have touched on this, but I thought I'd clarify a few things: \n\n* 1: \"Opportunity Cost\" - If you make your password easy to brute force, it'll probably get broken in to before hackers even make it to the server. If a computer system is poorly secured, you can often just try password guesses over and over. I can also tell you, as a systems administrator, there's a certain percentage of users who will always take the bare minimum password. \n\nHackers are lazy, and will take the path of least resistance. Think of it this way - what's the point of locking your car doors if someone can just break the windows to get in? Most people still lock their doors when they leave their car... \n\n* 2: Protection *After a Breach* - To understand why this is important you need to know 2 things - How passwords are stored, and how passwords are stolen.\n\nPasswords *shouldn't* be stored in \"clear text\". There are a set of mathematical equations called \"[hash functions](_URL_1_)\" They take in a number A and output a number B. The special, important thing about hash functions is that they're not reversible. This means if I put in A, I'll always get back B as the result. But if I have B, I can't just run the equation backwards and get A. Most well secured systems also use what's called a \"Salt\". While the truth is a little more complicated, you can think of a \"salt\" as an extra password that just gets automatically added to everyone's passwords. A different salt is used for each user.\n\n*EDIT TO ADD*\n\nWhen you make a computer system that uses hashed passwords, how do you check if a user is allowed to log in? Simple - when a user puts in a password to log in, you just run it through the same hash algorithm you used to store the password the first time. If the outputs match, the inputs should also have matched. It's *possible* that two different inputs can produce the same output (this is called a collision), but a well designed hash algorithm makes it very, very difficult to figure these out. \n\nSo now let's try to steal some passwords. I'm a hacker, and I've just stolen a password database from LinkedIn. I didn't actually get everyone's passwords - when I look at the database, I don't see: \n \n \"SgtKashim: Hunter2 | _Dihydrogen_Monoxide: Password\".\n Instead I see: \n\n \"SgtKashim: 5648f87c4bfdbe1edab312f2148261bc | _Dihydrogen_Monoxide: dc647eb65e6711e155375218212b3964\". \n\nOr with the salt added: \n\n \"SgtKashim: 5648f87c4bfdbe1edab312f2148261bc: 1521 | _Dihydrogen_Monoxide: dc647eb65e6711e155375218212b3964: 7852\". \n\n\n I do a little more poking around, and I figure out that LinkedIn is using the [MD5 hash algorithm](_URL_0_) to store their passwords (side note - MD5 is not secure). Since I know MD5 is not reversible, but I want to figure out all these passwords... How do I figure out the passwords? Well... I know if I put in A, I'll always get B out. What I can do to figure out the passwords is try running each *possible* password through the MD5 function till I hit one where the \"B\" that comes out the end *matches the hash stored in the database I stole*. \n\nLet's say I start by using all the words in the dictionary. I run each of those through MD5, then take a look at what comes out. Since SgtKashim's password has a number in it, I don't find a match. _Dihydrogen_Monoxide's password, though, gets found when I check the word \"Password\". \n\nBy requiring the passwords to be more complex - that is, make them longer and have numbers and letters and capitals and symbols - the number of possible things a hacker has to include in their guesses goes way way up. The *hope*, anyway, is this will make guessing the passwords take so long that hackers won't be able to get useful passwords out. \n\nSo back to our hacker. The hacker is trying to figure out every password by looking at the hash, then hashing every *possible password* and comparing the results. This takes a long time. To make things faster he decided instead to make a \"Rainbow Table\". Instead of hashing each password and checking, he hashes as many possible passwords as he can think of ahead of time - millions upon millions of them - using the common hash algorithms. This takes a lot of computer time, but when he's done it means he only has to do it once. When he steals a password database, all he needs to do is a simple text search to see if any of the stolen password hashes match the hashes he's already computed. This is what a \"salt\" fixes. By adding the salt to the password we've rendered his whole table meaningless, and he'll have to go back and rebuild the whole table using our salt for each individual user, wasting a whole bunch of his time. The salt is stored in the table, but since each user has a unique salt... You'd have to compute a rainbow table for each user you're trying to crack. \n\nThe truth is there's no encryption that's absolute. Given enough time, all encryption can be broken (barring systems that wipe the data when they're tampered with...). Protecting data is really about making it take so much time that it's not practical for anyone to steal. ",
"A strong password assumes the database isn't hacked. For the basic confines of password strength, don't think about how it's stored, whether the storage can be hacked, or whether a hacker can/will use the password on other sites, and even that the hacker has only 1 try before they are locked out.\n\nA weak password is much more likely to be guessed by a hacker than a strong one. If you used 'password' you'd be far more likely to be hacked than 'hepf72;gis6gHa', simple because a hacker is more likely to guess 'password'.\n\nSo a strong password is simply less likely to be guessed.\n"
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cn1x49 | why is clicking a pen so satisfying when you are the one doing it but so annoying when someone else is doing it? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/cn1x49/eli5_why_is_clicking_a_pen_so_satisfying_when_you/ | {
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"When you're doing it, you get the feeling of the pen button clicking into the pen synced with the sound. When someone else is doing it, all you get is the sound.",
"To me it's the control of when to do the clicking (so the sound is just a by-product) vs. the lack of control when someone else does it and you can only hear the sound."
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1xdn04 | what gives us the ability to perfectly recreate a sound in our heads without being able to actually vocalize that sound? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1xdn04/eli5_what_gives_us_the_ability_to_perfectly/ | {
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"You're vocal chords aren't the same as for example Freddy Mercury. So while you can think about what his voice sounds like, you don't sound like Freddy Mercury so you can't sing like him. Same for animal sounds etc. ",
"How do you know you are perfectly recreating a sound in your head? Your head tells you it is."
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8japlw | how do headphone jacks work? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/8japlw/eli5_how_do_headphone_jacks_work/ | {
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"A picture is worth a thousand words they say, so here is what happens when you plug it in:\n\n_URL_0_\n\nOnce you plug it in the two contacts you can see at the top are separated, this is then registered by the device and sound is redirected to the headphones.\n",
"Is there an ELI5 for how Apple uses the same port for headphones and charging?"
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6easf3 | what is the origin of the "http://" before a website address, what is its purpose, and why is wikipedia's "https://" a significant difference? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/6easf3/eli5_what_is_the_origin_of_the_http_before_a/ | {
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"\"something://\" indicates the protocol being used. The protocol is the system/rules by which your computer and the remote server that has the webpage talk to each other. There's actually many, and some other ones used to be more popular, but these days http (hypertext transfer protocol) is by far the most commonly used, and if you don't specify a protocol the computer assumes that one. (ftp:// is still in use though gopher:// has long since fallen by the wayside.)\n\nSo what's http**S**? The S stands for secure. It's the same system as http, except encrypted so that as your communications pass over the internet, it's much harder for anyone to potentially snoop on you.",
"HTTP is not encrypted, so if someone was sniffing through your network as you went on an HTTP site then they would get all that information. \n\nHTTPS is encrypted, notice how whenever you login to your internet banking (chrome for example) there is a lock behind the https. \n\nMost modern sites are HTTPS due to huge security risks with data not being encrypted. ",
"Back in the early days of the internet, you had to directly connect from computer to computer, and know the computer's exact address. As the internet grew, some computers started acting as servers that you could access through various protocols. You can tell a protocol is being used because there is a :// between the protocol and whatever comes after it.\n\nOne protocol is HTTP, which stands for hypertext transfer protocol. When you connect to a server such as Reddit with HTTP, your computer is saying, \"Hay, Reddit server, I'd like a webpage pls.\" Reddit replies, \"k here's your webpage thx\" and delivers the usual text/images/video/etc. that we usually expect from web pages.\n\nThere are other protocols out there besides HTTP. For example, FTP, or file-transfer protocol, is used to directly download/upload files. So the owner of Reddit might decide that instead of browsing to the Reddit home page, they'll use an FTP program to access Reddit's files. Instead of seeing a pretty web page, they'll see a group of folders much like the file explorer on your home computer. And then they can manipulate those files in much the same way, such as by replacing all the site images with lolcats.\n\nSo let's say you see a cool link on Reddit to the Mooby's Swag Shop website, and while on that website you see a REALLY COOL HAT! Of course, you must buy it. So you enter your credit card info, and click send. However, you fail to notice that Mooby doesn't know what he's doing and he let you send your credit card number over the HTTP protocol. This is unfortunate for you, because your next store neighbor Nosy Nancy has been watching all the information you transfer over HTTP, and as soon as she sees your credit card number she logs onto Amazon and goes on the shopping spree of her life. Whoops!\n\nWhat Mooby should have done is change his Swag Shop to HTTPS protocol, which stands for Hypertext Transfer Protocol Secure. With this protocol, the computer you contact gives you an encoder to scramble up your message, and it can only be decoded with the decoder kept secret on the other end (it uses a nifty mathematical trick where the encoder can encode the message, but it can't actually decode the message back without the decoder!) This way, when you type in your credit card number and hit \"send,\" your computer encrypts it up, sends it to the Swag Shop, and then the Swag Shop decodes it. If Nosy Nancy listens in, all she gets is gibberish - she does not get your credit card!\n\nIt used to be the case that HTTPS was a much slower protocol than HTTP, so it was only ever used for credit cards. But nowadays the speed has caught up, and the criminals have gotten smarter. Many of the big companies have raised concerns about even your logins for websites being snagged by the Nosy Nancys of the world, since they could theoretically snag your username and password off Reddit and try it on every major bank's website (since at least some people will use the same combo for both.) So in recent years Google, Firefox, and Apple have started pushing website owners to switch any page with a login screen over to HTTPS (with an eventual role of getting the entire internet to switch to HTTPS).\n\nAlso, it's important to note that there are different levels of HTTPS. If you look to the left of the HTTPS on a given web page in your browser, you'll see a lock icon. Clicking on that icon tells you what level of security it has. The most basic level of security is, \"This website is encrypted, but we have no idea if it's legit.\" The highest level of security is, \"This is a real world business that's registered in a specific country and has submitted all its paperwork to prove it's the real deal.\" \n\nFor example, on this website, I can click on that icon and view the certificate to see that _URL_0_ is owned by a company called Reddit Inc., and has been verified to be the real Reddit by DigiCert Inc., but I can't see the real world owner of the company. On the Bank of America website, I can see that it's the real Bank of America site and that it's owned by the physical Bank of America company based out of Chicago, Illinois. Why is this important? Well, if you're on someone's blog, just being encrypted is good enough, you don't really need to trust the person who owns the blog. But if you're directly depositing all your paychecks into a bank account, you want to make sure you have a ton of trust that the website you do your banking on is actually owned by your bank, and not a scammer trying to get your bank account number.\n\nTL;DR: HTTP lets you view webpages. HTTPS lets you view webpages securely. HTTP is becoming outdated, and you can expect to see most major sites switch to HTTPS over the next couple of years."
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yunqx | why do we have pubic hair? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/yunqx/why_do_we_have_pubic_hair/ | {
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"A few reasons. It reduces friction during sexual intercourse, being the biggest one, as well as friction between the buttocks and thighs. Hair also serves a hygenic function -- it wicks away sweat, spreading it over a wider surface area and allowing it to evaporate more quickly. When someone gets BO, it's not their sweat itself that stinks, it's bacteria that live on the skin, nourish themselves with sweat, and excrete smelly substances. If your sweat evaporates fast, this doesn't happen as much -- which is why we have hair in our armpits and on our crotch, where sweat has lots of nooks and crannies to gather.",
"You're five; We'll have that talk when you're older.",
"i noticed that i smell good longer when i have shaved armpits than unshaved.\n",
"It's a conspiracy by the razor companies. ",
"Speak for yourself. I don't have pubic hair.",
"My dad once asked me why we don't grow pubic hair to our knees and why it stops growing so short. I think I just looked at him then walked away. ",
"try shaving it off then going for a bike ride or hike in the mountains, then you'll see.",
"In a similar vein, why are we pretty much hairless? Why was hair selected out of our genome?",
"one day when you are older and you have pubic hair, something will compail you to shave it. You will then understand that it reduces the friction between your junk and your legs as well as the friction between your legs walking. Sweat will cause more friction and allow for shit like jock itch to get out of control. It's that day that you will say to yourself, \"man, I really liked my hairy balls\" ",
"Saw a show on discovery(?) about the science of sex that said that one factor of it is that, in the case of men, the places where they have hair, there are certain bacteria that live there that produce a pheromone which, if a woman is ovulating, she will be drawn to. The same woman, when not ovulating may find the same smell repulsive.",
"As a way to identify sexual maturity from a distance. I just made that up but it makes sense. Sort of. ",
"[There's hair around your holes to protect them.](_URL_0_)",
"not too many people do have pubic hair these days.",
"reading this thread I can't stop wondering how I managed to live the first ~14 years of my life without them.."
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8h2luh | can someone explain to me how anorexia nervosa works | Specifically I don't understand why survival instinct doesn't kick in to save the victim | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/8h2luh/eli5_can_someone_explain_to_me_how_anorexia/ | {
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"It's a DISORDER. Psychiatric issues are no different than other disease processes. That's like asking why our body doesn't just heal itself if it has a virus or diabetes or cancer. There is a pathophysiology associated with the brain just like there would be with any other organ in any other disease.",
"Because it is a mental disorder on par with schizophrenia and other mental health illnesses. Just like it seems like a high functioning member of society who happens to have schizophrenia seems like they should be able to realize it's not even remotely logical to think a pre recorded tv show is directly talking to them an anorexic person is unable to control their eating behaviors. Yes a lot of anorexics know they are in danger, a lot of them spend hours researching anorexia and reading stories of others with it so they know logically when they see their hair fall out or when they're so weak they almost faint every time they have to climb a flight of stairs that they are ill, they are simply unable to force themselves to change things. Some anorexics on the other hand don't realize there is a problem, or at least not as big a problem as there is and some are flat out in denial...it's really no one exact way for every anorexic individual. The same way a person can smoke themselves into an early cancerous death survival instinct doesn't kick in and say hey what you're doing is dangerous and so they continue to smoke just like an anorexic person continues to starve or purge or utilize whatever their methods may be.\n\nThing people don't realize is anorexic, just like bulimia and EDNOS are all mental health illnesses, that literally affect how the brain works and changes/takes away their ability to make rational choices. I've had anorexia as a teen and I can tell you there are few things as powerful as the anorexic brain, I KNEW I was making myself sick, I KNEW what I was doing was dangerous, I spent days reading books about anorexia, I simply couldn't stop myself. \n\nAnother thing to consider is most anorexics have body dsymorphia, which means even when they are 90 pounds they may sincerely not be able to see their sunken in bones or their rail thin arms...,that's how it was for me, I got almost down to 100 pounds and was so skinny I had to be looking quite frail yet I literally thought I looked somewhere around maybe 150, 140 or something like that. That mental disorder also comes into play with anorexia further compounding the disorder and legitimately making it impossible for an anorexic to physically see what other's see when they look at themselves."
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2m9jbf | why do some people say fall, while others say autumn? is this varied by country or preference to a certain word? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2m9jbf/eli5_why_do_some_people_say_fall_while_others_say/ | {
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"IIRC, \"fall\" fell out of favor in England some time in the 17th or 18th century, but remained the standard term in America.",
"Europe: We call it Autumn, from the French word \"autompne\" and later, the Latin \"autumnus\". \nUSA: WE CALL IT FALL BECAUSE LEAF FALL DOWN"
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c2jnmd | - how does a single 3.5 mm jack provide stereo sound? | So on my way back home I was listening to music on my bike and I got fascinated by a sound panning from left to right in my earphones. (I was listening Ready or Not by the Fugees). How does a single contact like a 3.5 mm jack provide a stereo sounding effect? How is it able to split the sound between both earphones? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/c2jnmd/eli5_how_does_a_single_35_mm_jack_provide_stereo/ | {
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"You will notice black bands on the jack. Stereo will have 2 bands, making 3 connections; L, R, and common. Some new headphones with buttons will have extra bands.",
"There is a separation on the plug end (little black liners that separate the metal segments) these separate segments connect to wires that feed each individual earphone and allows multiple channels from a single plug.",
"A 3.5 mm jack isn't a single contact; it's three. A standard headphone jack can therefore carry three signals. In most that's left ear, right ear, and ground. You can get 3.5mm jacks with more contacts too, some have 4 or even 5 and so can carry microphone or video data as well as stereo audio."
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2i4x0q | why is washington "redskins" considered offensive but the cleveland indian's logo of an indian with red-skin is not? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2i4x0q/eli5_why_is_washington_redskins_considered/ | {
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"Redskin is seen as a more offensive slur than Indian...",
"Cleveland Indians' mascot is controversial. Same with Kansas City Chiefs and Atlanta Braves. You can read all about it on Wikipedia:\n\n_URL_0_",
"Many people consider that logo offensive. Look on _URL_0_'s standings page and see what logo they have there for the Indians.",
"They're actually both controversial.\n\nIt's not actually the name that's the biggest problem, it's the mascot. If it was the Redskins and it was an image of a Red bird and their mascot was a bird, no one would probably care. But they treat indian peoples as sort of characters like they're animals.",
"It's because Native Americans have referred to themselves as \"Indian\", but they've never used the term \"redskin\". Redskin has always been a derogatory term.\n\nThat said, people have tried to get the Cleveland Indians to change their mascot, and there was all sorts of hubbub with the Atlanta Braves \"tomahawk chop\" that the fans used to do."
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245jvl | why is it that, with age, women have an increased sex drive along with an increased risk of birth defects in their children? | If I understand correctly, women tend to have their highest libido when they reach 30-40 years of age. However, past the age of 35, women also start to have a higher risk of having children with birth defects. I would think that, from an evolutionary standpoint, we would want women to have their sexual peak coincide with the best time to have healthy children. Instead, it looks like this higher sex drive would lead to more unhealthy births, since at-risk women are likely to have more sex. Why would this happen? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/245jvl/eli5_why_is_it_that_with_age_women_have_an/ | {
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"I don't think the increased libido is biological i.e. hormones etc. I'd put my wager on an increase in confidence and maturity. Many things can affect libido for a woman, and the typical 'I don't give a shit anymore' attitude that comes with age can boost self confidence dramatically.\n\nI also remember it being in the media nearly 20 years back that pill can cause breast cancer. The pill can cause a drop in libido, 20 somethings may not be interested in 'the news' or 'cancer is for old people' (remember this is 20 years ago), most women 40+ probably aren't on the pill anyway, but the 30-40 demographic would be old enough for cancer to scare them AND be taking the pill, so they stop the libido reducing drug. If a study then tried record the results they'd see a skewed libido increase for the 30-40yo population as a whole.\n\nIt's 4 am so this is just late night ramblings with no sources to back it up, but I don't think its that far off the mark. Or I could just be talking out my ass -.-"
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dpojsg | when someone gets measles, how does it "reset" the immune system? what's the process whereby it does this? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/dpojsg/eli5_when_someone_gets_measles_how_does_it_reset/ | {
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"Basically, measles induces immune suppression through immune amnesia. This causes the immune system to forget how it has fought off other diseases in the past and leaves it with a high chance of vulnerability to other pathogens. Thus \"resetting\" the immune system.",
"The Measles Virus creates suppressants that lower the over all strength of your immune system and cause an effect called \"immune amnesia\" where the immune system effectively forgets all the various pathogens that it has learned to react to for a period of time. Most of this \"memory\" will come back after you have recovered from measles but sometimes they do not and you need to vaccinate anew.",
"Extreme oversimplification: how does your body recognize foreign things? It makes cells that are sensitive to random things, anything really (literally mixes up DNA to generate random receptors, this is called somatic hypermutation), then it exposes these cells to the body itself, If they react, body kills them if they don't, they're let go and they mature elsewhere, much like a school. And then they go around the body. When something foreign infects you, like a bacterium, one or more of these cells will recognize it because it so happens to have a receptor that is sensitive to them. The ones that get activated, proliferate (divide) making a lot of themselves, to fight that specific bacterium (this is called clonal expansion). And then when the infection is gone, some of these cells go to lymph nodes and just stay there, as memory cells. They're known to be sensitive to this one type of bacteria, so that's how the immune system saves immunity information. If a pathogen you've been exposed to before infects you again, you quickly recognize them and kill them before they spread, that's how memory is useful, and that is how vaccines actually work. Then enter measles. Measles virus weasels it's way to lymph nodes and infects those memory cells causing them to die. And now you lost your memory to a bunch of things that previously infected you. So it's called immune amnesia. You can rebuild it, but still, you're left susceptible for a few years after.\n\nEdit: added some terms in case you'd like to Google further"
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c5vgor | why is it ok for the yolk of eggs to be consumed runny but not the whites? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/c5vgor/eli5_why_is_it_ok_for_the_yolk_of_eggs_to_be/ | {
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"The yolks of eggs are doubly sealed from the outside, reducing the risk of salmonella. Not to 0, so hard boiled eggs are safer, but among the risks in life, runny egg yolks aren't really high risk.",
"It's more of a personal preference thing than anything else. People *like* eating runny yolks, they usually don't like runny whites (possibly because the whites are more gelatinous, compared to the smoother liquid of the yolk). Both are more or less equally safe.",
"That’s not a thing. Both are equally safe. The whites are just gross and slimy when partially cooked, and the yolk tastes nice. My friend drinks a protein shake with a raw egg every single day of his life.",
"So only about 1 in every 20,000 eggs are infected with salmonella. Meaning, the risks of eating raw or partially cooked egg is quite low."
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19n371 | - why does usb transfer rate fluctuate? | Why does the transfer rate fluctuate when I'm moving a file from a flash drive to my computer, instead of staying at a constant rate? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/19n371/eli5_why_does_usb_transfer_rate_fluctuate/ | {
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"text": [
"it could be one of two things\n\n1) you are using a mechanical hard drive and it has to spin and search for different free sectors to save the files to.\n\n2) you are copying alot of folders of different sizes. the copy progress bar is based on what file you are currently copying and how many files you have total. if you have 3000 files, 2999 of them are 1 MB and 1 is 1 TB, it will base the progress as a percentage of 3000 files until it finds the huge 1 TB file. then it will start to take that into consideration. "
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6t2k1g | why apple products need to be updated every other week | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/6t2k1g/eli5_why_apple_products_need_to_be_updated_every/ | {
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"Because they (Apple) are finding bugs in their code constantly (and sometimes, feature upgrades - but mostly bug fixes). The same reason Microsoft releases updates to Windows monthly.",
"There are different reasons for that. \n\n1) security reasons: Apple is very concerned with the security of their devices, both because of the fact that they want to maintain a close system and because they want to maintain a reputation. \n\n2) better customer care: Apple rolls out updates more frequently to maintain a strong base of customer satisfaction. They have always encouraged updates and made them more easily available over time. \n\n3) helping out developers: this is closely linked to the second point. Having a uniform base makes it easier to develop apps and program, i.e. Windows programmers must make sure their software works on XP, Vista, 7, 8 and 10, while the latest version of os X has been delivered to almost 80% of customers. \n\n4) bug fixes: of course system as complex as ios will have bugs, and the fact that it is widely used make those bugs easier to find (the more users, the more bugs found). \n\nHope this helps"
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1rvw94 | why hasn't anyone try and improve some of the horrible conditions of the foster care system? | I have heard a lot of horror stories about the foster care system and how poorly it treats the kids who go in it. I am wondering why no has tried to improve the conditions or at lest make some sort of an effort to limit the continued abuse.
I know not all foster parents are like this but for the ones that are.
Sorry if I got this wrong it is my first time posting.
Thank you in advance.
**Edit: I should probably mention that I am from Canada. I know that doesn't make much sense. But I see a problem that is causing a lot harm to people who have already been hurt, and I rather help try and fix it (even in my own country) than staying silent and letting the abuse slide.** | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1rvw94/eli5why_hasnt_anyone_try_and_improve_some_of_the/ | {
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"Because the government doesn't really see what's wrong with it. \"If it isn't broken, don't fix it.\" ",
"I think the answer to this is where would the money come from. There are lots of proposed solutions but that takes time (which has a value all its own) and money. So far nobody wants to fund a solution to the problem that isn't guaranteed to produce unbelievable results. In short nobody wants to fix the problem because it doesn't have an immediate impact on the individual.",
"A lot of sensible reforms are not worth the political risk to those who have the power to make them happen.\n\nReforming foster care is REALLY HARD -- there aren't obvious solutions that are sure to work. There are no lobbyists for it offering to write draft legislation for you, there's no corporate money to support the cause, and no public movement rallying behind reform.\n\nAnd if you DO succeed in reforming the system, then you've staked your career as a politician on that reform -- you OWN that issue. Any bad news is YOUR FAULT. If it fails, you're done in politics. Even if fewer kids die or are abused after the reform, the first kid to die afterward is going to be associated with your name for the rest of your (short) political career.",
"I'm glad someone is at least asking this question. It has haunted me since I aged out of America's pestilential foster care system over 20 years ago. The experience was traumatizing and I was placed in a home with abusive, violent alcoholics. The system still sucks and kids are murdered, raped, and beaten by foster parents on a regular basis.\n"
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7b3zr9 | what is thinking? why do we have to `learn to think`? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/7b3zr9/eli5_what_is_thinking_why_do_we_have_to_learn_to/ | {
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"Id say its the process of understanding; looking at a situation or thing and being able to comprehend every bit and how it works together, and what you should do with that information. If you just go off of instinct or whatever the first thing to come to your mind is, you make really horrific decisions. \n\nSay you get contacted by a prince from Zimbabwe offering you a million dollars if you put down 100 now. If you were never taught to think things through, you might think this is a good idea. However, take a second to think it over and you learn that it is a scam",
"I'd say that thinking is the process of arranging the information you already know using it in a way that is useful. When you learn data is like you are adding random pieces to a puzzle. When you learn how to think, you spend time looking at those random pieces and connecting them together where they belong. Afterwards, the final image is what you use in your life.\n\nUsing the scam example other commenter used: knowing what money, Zimbabwe and scams are are the random pieces. Connecting all the concepts together, and reasoning why it doesn't sound like a good idea is learning the process to think. Using the knowledge that this is a scam to avoid other similar scams is using the revealed \"image\" for a real life issue. ",
"Well, what is thinking? It is firstly a way to identify things, including ourselves. It is how we know what *we* are as selves, and a proof for ourselves that we are distinct from other things. Thinking is an emergence that occurs in intelligent beings (not only humans).\n\nThinking *is* consciousness. It is the hallmark of being a person. Without thinking, what is there? Automatic response to a stimulant. Limited learning through cause and effect, or innate behavior. One could argue that our brains are pretty similar, and that thoughts are actually constructed in a predictable manner based on our environment. Noam Chomsky believed this. \n\nBut even if that is true, our thoughts are pretty unique. It defines us as unique individuals. Very rarely do two people actually share the *exact* same experience, and thus share the *exact* same thought patterns. There will always be some sort of deviance if there is even the smallest difference.\n\nThere are also different types of thinking. We learn to think more *critically* because it helps us as individuals. It helps us solve problems much faster than we would with trial and error. It helps us avoid the consequences that would force us to learn things the \"hard way\". For example, if you know that fire burns wood, it is beneficial to be make a small connection that fire might also burn your skin. Being able to improve our thought process is incredibly beneficial to us. ",
"We know a lot of things. We know we can create a fire out of wood. We also know touching a hot iron hurts. We know fire is hot. But if we know these things, yet don't process (think) that information, how would we know that sticking one's hand in the campfire hurts?\n\nThinking is processing the information we have. This allows us to figure out things we wouldn't otherwise know, such as the hand + campfire = bad example used above. If we couldn't think, only know (= possess information) we would have to try everything to know what would happen. We would have to try every knife we get our hands on to know if it actually cuts, and then try cutting ourselves to see if it hurts.\n\nBut since we can think, we know the general structure and look of a knife, and thus we can see if something fits those general criteria of a knife, it most likely is a knife, and will cut, and also hurt if you cut yourself with it. Thinking, in essence, is processing the information you have and combining them to get new information you didn't have before.",
"A few people have answered that thinking and learning to think are essentially related to understanding and pattern recognition, but I'd like to add that when we talk about thinking (as opposed to just 'fact-knowing') we're also talking about what thoughts we think are useful.\n\nEverybody thinks - children, academics, politicians probably - but when people talk about clever or 'good' thinking they basically just mean the thoughts that contribute towards a particular discourse or narrative most clearly, coherently, or usefully. Stupid thinking is thinking that does none of that. \n\nIf we imagine a detective looking at a crime: \nIf they're a good detective, they'll have learned to think along the particular narratives usually relevant to crimes - a bloody knife at the crime scene probably isn't there because someone did some meat prep, unless the crime scene is actually a butcher's shop, in which case it won't be useful to automatically consider ever bloody knife as a murder weapon.\n\nBad thinking would be a detective that walks in and fails to understand the narrative, coming to a conclusion that isn't clear (e.g., the logic behind it doesn't make sense), isn't coherent (their conclusion follows a logic, but not the one we typically understand), or isn't useful (their conclusion has nothing to contribute to the efforts to solve the crime). \n\nAlternatively, if a teacher complains that a schoolchild need to learn to think, they mean that they need to learn to follow the logics and consider the things that that teacher deems useful. Obviously a child behaving selfishly or ignorantly is still thinking, either about themselves rather than others or about something totally irrelevant, but as far as the teacher is concerned, they aren't thinking about the right things in the right way.\n\nOn the other hand, as a somewhat different approach, here in the West we're very heavily influenced by Cartesian discourse, and its pretty much the universal case that people have been taught - passively and actively, by individuals and by the way our institutions are configured - that we are isolated individuals rather than nodes in a network of relationships, and that things exist discretely rather than fluidly. In this context, learning to think is more about learning how to 'shape' our thoughts - or probably more accurately, having our thoughts 'shaped' - by the environment we come to exist in. \n\nEdit: sorry, just realised how long this is. TLDR: learning to think is about learning how to think along the lines that make us useful to other people.",
"Thinking is the way we organise our thoughts. This helps us understand things, or it can also be a distraction when you daydream, worry about something, etc.\n\nWe have to learn to think because it is a learned skill. Not knowing how to think is like trying to cut wood with a blunt saw. You'll get something done, but it may not be complete, and you sure as hell are going to spend way more time than is needed. It's going to be faster and more effective if you have the right tools. Thinking is a tool. Learning to think is sharpening that tool. ",
"Thinking is collecting facts you see or just know, and arranging and comparing them in your head.\n\nWe learn to think so we can solve problems. If we learn to think well, we can solve problems more quickly, or with less work.\n\nNote that I’m talking about real world problems, like “where is my next meal coming from?”",
"What is thinking?Thinking is what your brain does. Imagining is thinking. Planning ahead is thinking. \n\n\nWhy do we have to 'learn to think'? When a person spends time to plan ahead, it usually has a better outcome. We need to practice thinking about the future so that we can be prepared. Example: if a person is going to the grocery store, it is better for them to think of all the things they need and make a list rather than driving to the store without thinking about what they need. ",
"Here is ELI5 from the lou. \n\n:Humans are born with the ability to recognize patterns; after recognizing a few, humans start making predictions based on past patterns. That is how we \"learn to think\"",
"Thinking is connecting pieces of knowledge we have into new ideas. Some knowledge we get directly from experience: \"I am hungry\" and \"I know there's a cafeteria down the street\" and \"I know that at a cafeteria you can exchange money for food\" and \"It takes time to buy and eat food\" but \"there will be consequences if I don't get to class on time\". All of this knowledge gets connected through thinking to a new idea, in this case, a decision: \"I will go to class and endure being hungry\", or \"I will go get food and endure the consequences of being late to class, because being hungry would be worse.\" \n\nThinking is how we convert our knowledge into action, and how we connect knowledge to make new ideas. One has to learn how to think because one has to gather knowledge with which to connect thoughts, and there are some well developed methods of connecting knowledge (like the methods of mathematics, of deductive reasoning, of reasoning by analogy, etc.).",
"\"Thinking\" means many things. Some types of thinking is innate, but we refer to this as \"having thoughts\" more often than as active \"thinking\". Examples: \n\n* talking to yourself in your head\n* The search for water when you're thirsty\n\nOther thinking has to be learned, and this is mostly what we value, because it is a conscious thing between an sensual experience and an action. Examples:\n\n* Thinking logically\n* Formulating a sentence or a story\n* Structuring your time and space\n\nAn interesting type of thinking is the reflection upon itself. It clarifies and restructures the sort of thoughts we think. The impulse to do this meta thinking is innate in some people, but to do it effectively requires certain techniques that have to be learned, such as\n\n* psycho analysis\n* meditation\n\nMuch more can be written, but for a 7yo it's probably sufficient to point out the difference between \"having thoughts\" and \"active thinking that results in an action\".",
"This is a difficult to do as an ELI5 because it's not something that can be easily proven. There are a lot of theories from different psychologists and neuroscientists about what thought is. It also depends on how you define the word thought, which people might have different opinions on. So to summarize what \"thought\" is in a sentence or two makes a lot of assumptions about these things. \n\nSo let's just take a look at one theory from Charles Fernyhough, a professor at Durham University who specializes in developmental psychology with a focus on social, emotional and cognitive development. I'm paraphrasing his work extensively, but my understanding leads to this summary:\n\n > **Thinking is using language to correlate multiple words (or symbols) to create meaning.**\n\nYes, he believes words are *necessary* for thought. It's more than just a running dialogue in our head; having words is a necessary part of our ability to perceive and understand our world in a complex way. This isn't some crackpot theory. It's been studied with a reasonable amount of scientific rigor. Fernyhough goes over some of that in his books, but for a great summary of some of his ideas and their evidence, there is a great Radiolab episode about [Words](_URL_0_) which goes into it. His segment starts around 10 and a half minutes into the segment. \n\nLet's take a creature like a rat (discussed in the segment). They able to perceive the color blue. They are able to perceive directions, like left and right. But they are incapable of putting these two concepts together. Meaning, they can't understand \"left of blue.\" The theory is that language is the thing that unlocks the ability to put together these concepts. And the theory is somewhat reinforced by the fact that children before they have language act very much like the rat. They can perceive blue; they can perceive left/right. But they can't understand \"left of blue.\" But once they start unlocking words, they start being able to connect words together. Eventually, they are able to create more and more complex thoughts. \n\nI could summarize the contents more, but I would just be ripping off their work. So I recommend giving it a listen. I honestly think the segment is well done enough for a 7 year old to understand some of. Radiolab does a great job of taking complex ideas and making them simpler to understand. "
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despit | can a person with alzheimer’s disease get addicted to drugs or would just forget about it? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/despit/eli5_can_a_person_with_alzheimers_disease_get/ | {
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"Not an expert but...\n\nMost addictive drugs are addictive because they permanently alter the chemistry of the brain, which they couldn't \"forget\" about.",
"Someone with greater knowledge than me is probably typing up a well written explanation as we speak, but basically yes. Your body would have the chemical addiction the same as anyone else. You can however forget where the feeling came from, and lack the memory to know what you are feeling is withdraw, and that drugs is what will make it go away.",
"The physical symptoms of withdrawal are not dependent upon memory. Common examples: a person with Alzheimer's who was opioid-dependent or on SSRIs will experience withdrawal (nausea, sweating, irritability, fever) if not continuing to take the medication.\n\nSource: Pharmacist.",
"Ive heard many stories about patients who learned to fear an abusive caretaker, or whose face light up at a son in law (or grandson in law) they don't know, but learn to know they like. Aversions are learned at a very base level, so it's not surprising if that is the last part of the brain to go before complete dementia sets in. So, as others pointed out, physiologically you could get addicted, i belive you could be psychologically as well.",
"My dad had a stroke from long term (20+ years of heavy drinking) alcoholism and lost oxygen to the brain for enough time that he had brain damage and was paralyzed from the waist down.\n\nWhen he awoke and was coherent and even tried physical therapy for a while, he had absolutely no memory that he had been a drinker or smoker (2 packs a day) and basically did the physical withdrawal symptoms while in the hospital after the stroke.\n\nDidn’t drink or smoke all the way until his death 7 years later.",
"My mom got tired of taking my grandma outside to smoke so she told her that she quit smoking years ago and she doesnt smoke anymore. Grandma was satisfied with the answer and she hardly ever asked about going out for a smoke. Just a random memory I wanted to share"
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nm4ud | how to maximize the security of your computer. | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/nm4ud/eli5_how_to_maximize_the_security_of_your_computer/ | {
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"It depends what you mean by security.\n\nIf you mean against viruses, malware, keyloggers, and other stuff like that, you want a good antivirus setup. At the moment, the best free antivirus is (surprisingly) Microsoft's Security Essentials (MSE for short). It works in real time, which is what you want when you're looking for antivirus software as it can nip any problems that occur in the bud. Another piece of software you'll want is Malware Bytes Anti-Malware, which is a more thorough program. This one isn't as good for running all the time- it uses a lot of resources, and is overkill for most users- but it's useful to have it around and run it every few weeks. It looks at files you already have for malicious software, on top of the lighter checking MSE does.\n\nIn terms of data security (looking after passwords and stuff) I don't have all that much experience. One thing I can recommend is truecrypt, though, as it's free and undeniably secure. It can make a file that's encrypted using either one or a combination of the best algorithms currently available, which you can then use like a hard drive. If you have a long password, it's computationally impossible for the information in the file to be gotten at without your permission at this point; even with every computer humanity has, it would take several times the length of the universe to do it. truecrypt also lets you encrypt entire hard drives meaning you have to input a password before starting up, but again, this is probably overkill.",
"I cannot stress the importance of a password manager like [LastPass](_URL_0_) enough. ",
"It depends what you mean by security.\n\nIf you mean against viruses, malware, keyloggers, and other stuff like that, you want a good antivirus setup. At the moment, the best free antivirus is (surprisingly) Microsoft's Security Essentials (MSE for short). It works in real time, which is what you want when you're looking for antivirus software as it can nip any problems that occur in the bud. Another piece of software you'll want is Malware Bytes Anti-Malware, which is a more thorough program. This one isn't as good for running all the time- it uses a lot of resources, and is overkill for most users- but it's useful to have it around and run it every few weeks. It looks at files you already have for malicious software, on top of the lighter checking MSE does.\n\nIn terms of data security (looking after passwords and stuff) I don't have all that much experience. One thing I can recommend is truecrypt, though, as it's free and undeniably secure. It can make a file that's encrypted using either one or a combination of the best algorithms currently available, which you can then use like a hard drive. If you have a long password, it's computationally impossible for the information in the file to be gotten at without your permission at this point; even with every computer humanity has, it would take several times the length of the universe to do it. truecrypt also lets you encrypt entire hard drives meaning you have to input a password before starting up, but again, this is probably overkill.",
"I cannot stress the importance of a password manager like [LastPass](_URL_0_) enough. "
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5caiak | why do our eyes often suddenly perceive spinning movements as slower than their actual speed once a certain speed threshold is reached? | This refers to the effect often seen in strobe discs used for turntables, zoetropes for incredibly old films, and even things as basic as car wheels, in which at when objects spin fast enough our eyes suddenly view them as spinning slowly. Is this linked to saccades? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/5caiak/eli5_why_do_our_eyes_often_suddenly_perceive/ | {
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"Common misconception: Your eyes operate in a certain frames per second. The issue with this is that our eyes don't operate in 'frames.' It's much more complex.\n\nHowever, the frames per second method is the easiest way to explain it. So, imagine a camera is recording a helicopter. The camera is recording in a smooth 60 fps, and the helicopter's blades are spinning at 60 RPS (3,600 RPM- way higher than an actual helicopter, but this makes for easy math). So, each time the helicopter makes one complete rotation, the camera records a frame. It is in the same position as the previous frame, and as the next frame. This creates the illusion that it is in the same location.\n\nHowever, math doesn't always work out, so often, things will actually be just above or below this perfect threshold that allows us to see it in the same place. This creates the illusion that it's slightly spinning forwards or backwards. It might be different for different people- it's really based on how fast the brain can organize the information your eyes are giving you, however, there's always a limit. Your brain often simplifies the information it receives instead of completely ignoring it, resulting in motion blur."
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bbzwha | how do home satellite systems never lose connection to the satellite they communicate with? does the satellite orbit the earth at the same rate it spins? or are there multiple satellites that transfer the signal as they go by? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/bbzwha/eli5_how_do_home_satellite_systems_never_lose/ | {
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"Most satellites used for things like satellite TV are in geostationary orbit. They are over the equator and they go around the earth at the same rotational speed and in the same direction that the earth rotates, so they remain over the same \"spot\" of ground."
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f937mw | what can the average person do to help bring wealth to 3rd world and developing countries? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/f937mw/eli5_what_can_the_average_person_do_to_help_bring/ | {
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"I can get names of places to support but the general idea is, Help by supporting the opening of self stabilized facilities. However, in most 3rd world type countries outside involvement in this is banned by their government to reduce monopolization. Thus, the best thing to do would be to open up transportation and knowledge accessable to their general public, provide them with the ability to access clean water and sustainable housing methods using their immediately accessible resources."
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3wjssw | i believe in evolution, from all of the evidence there is. but i am just curious how there are no people in between us and monkeys anywhere. i know this may sound ignorant but i honestly don't know. why is this so? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/3wjssw/eli5_i_believe_in_evolution_from_all_of_the/ | {
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"First of all, humans didn't evolve from monkeys. Humans and monkeys both evolved from a common ancestor. Humans and monkeys are both apes. \n\nSecond of all, there are plenty of species in between, here is a list:\n\n_URL_0_",
"We didn't evolve from today monkeys, but we have a common ancestor with them. Millions of years ago a part of the population changed habitat and then evolved to fit better, becoming humans. The rest of the population continued to evolve on its own path to become today's monkeys. But since we split away they are no links between monkeys and us.\n\nExample : Iirc chimpanzees are the closest to us, and [we separated 5 millions years ago](_URL_0_)",
"Here is an overview of the Hominin family tree as it stands...\n\n**Quick Facts**\n\n* Humans are primates. All species classified as primate belong to the same order Primates.\n\n* Primates evolved about 60-70 million years ago. There are many different groups of primates that have now gone extinct. There are many different groups of primates that are still alive. The major groups of primates that are still living are the lemurs, the Old World Monkeys, the New World monkeys and Apes. Each group has many representative species. \n\n* There is no single trait that defines the primate order, primates are odd that way. Instead we have a collection of traits that together do not exist in any other group. We have forward facing eyes, can distinguish colours very well, have opposing thumbs, generally have large brain-to-body size ratios, have nails not claws...and so on.\n\n* Humans are apes. All apes evolved from an Old World monkey species about 25 million years ago. Apes, in contrast to monkeys, lack a tail. The living apes include: orangutans, gorillas, chimpanzees, bonobos, gibbons, siamangs, and humans.\n\n* We have many fossils of 'transitional species' within the primate order. We have a very complete human lineage as compared to many other fossil groups. For example, our last common ancestor with Chimpanzees and Bonobos lived about 7 million years ago. This [picture](_URL_1_) will clarify the following: this last common ancestor was not a chimpanzee or a human. It was its own unique species of ape that would split into two groups. One group, the 'pan' group would evolve into the living Chimpanzees and Bonobos. The other group, the 'hominin' group would evolve into a number of now extinct species and one living species - modern humans. I will talk more about the hominin group and the fossil species we have found.\n\n**The Hominin \"Human\" Lineage**\n\nOur last common ancestor with chimpanzees lived 7 million years ago in Africa. This last common ancestor was not a human, and it was not a chimpanzee, it was its own distinct species of ape. This last common ancestor would split into two populations. One population would lead to the evolution of humans, we call this lineage the 'hominin' lineage. The other population would lead to the evolution of chimpanzees and bonobos, we call this lineage the 'pan' lineage.\n\nFossil species hominin lineage are first found in Africa, between 5-7 million years ago. There are no fossils found outside Africa during this time.\n\n* [Sahelanthropus tchadensis](_URL_8_) is an extinct hominin species that is dated to about 7 million years ago, possibly very close to the time of the chimpanzee/human divergence. Some scientists are hesitant to classify this species as either a hominin or pan species, although generally it is classified as a hominin.\n\n* [Orrorin](_URL_7_) is the second oldest fossil specimen we have. We only have a few bones. It is 6.1 to 5.7 million years old.\n\n* [Ardipithecus](_URL_12_) species is a genus represented by two species: A. ramidus, which lived about 4.4 million years ago, and A. kadabba, dated to approximately 5.6 million years ago. We have a nearly complete skeleton and so we know a lot more about these species than the previous two. These species still had opposable big toes, and given the shape of their pelvis they very likely still walked quadrupedally (on all fours) in the trees. They probably spent some time on the ground as other features of their skeleton point to the beginnings of a bipedal stance. To keep it short, these species lived both in the trees and on the ground. They did not use stone tools.\n\n* [Australopithecus](_URL_3_) genus is represented by a number of species. It is very likely that an australopithecine evolved from an ardipithecus species. Australopithecines dominated the landscape of Africa from about 2-4 million years ago. They are the first species to make, use, and modify stone tools. Example species include: A. afarensis, A. africanus, A. anamensis, A. bahrelghazali, A. garhi and A. sediba. These species had an upright stance, walked bipedally, and had lost that opposable big toe. This tells us that their ancestors had already given up many traits that favour living in trees, for newer traits that favour walking upright or bipedally.\n\n* [Paranthropus](_URL_6_) genus is also represented by a number of species. They lived during the same time as some of the Australopithecines. These guys all went extinct, and are an evolutionary dead end. It is very likely that the paranthropus genus evolved from an early Australopithecine because they share many features.\n\n**Homo Genus**\n\n[Homo genus](_URL_13_) first arose about 2.5-3 million years ago. Humans are part of the homo genus. It is very likely that the earliest Homo species evolved from an Australopithecine. Homo species are mainly defined by their increased brain size.\n\n* [Homo naledi](_URL_0_) is probably between 2-3 million years old, but we are waiting on dating evidence to help us place them exactly. That being said the naledi fossils are a mix of old and new traits, being somewhere in between Australopithecines and Homo species which would place them somewhere around here in our family tree, being one of the earliest Homo species that evolved. They have a small brain (australopithecine trait) but they have more modern teeth structure (homo trait). Considering all the traits, the scientists decided to classify the fossils as Homo rather than Australopithecine. I will hedge a bet that there will be contention as to whether naledi should be classified as an Australopithecine or true Homo. \n\n* [Homo habilis](_URL_11_) generally regarded as the first definitive homo species in the fossil record. They evolved about 3 million years ago. There is some contention as to whether it should be in fact classified as a Australopithecine. Homo habilis is only found in Africa.\n\n* [Homo erectus](_URL_2_) is first found in Africa about 2 million years ago. There is no contention, Homo erectus is part of the Homo genus. Homo erectus very likely evolved from a population of Homo habilis. Homo erectus is also the first hominin species to leave Africa. Homo erectus left Africa about 1.8 million years ago and spread into Europe and Asia. They also used stone tools, and they also were able to use and control fire. They lived in small hunter-gatherer groups and very likely had proto-languages. The last Homo erectus fossils we have date around 140,000 years ago, and it is around this time that we think they went extinct.\n\n* [Homo heidelbergensis](_URL_9_) evolved from Homo erectus populations in Eurasia and Africa about 800,000 years ago. Homo heidelbergensis has a slightly larger brain size than Homo erectus. They also made, modified stone tools and also used and controlled fire.\n\n* [Homo neanderthalensis](_URL_10_) or 'Neanderthals' evolved from a population of H. heidelbergensis about 350,000-600,000 years ago. Neanderthals evolved and went extinct in Europe, they never left Europe. The last Neanderthals went extinct about 25,000 years ago. Neanderthals are the only known hominin species for which humans have definitive archeological contact.\n\n* [Denisovans](_URL_4_)...we don't know much about these guys because we only have a single finger bone, a single tow bone, and a couple of teeth to work with...so lets take their findings with a grain of salt. They lived about 50,000 years ago in Asia. They are very likely evolved from a Homo erectus population. It is unclear if humans every made contact with them, although there is recent evidence that we possibly interbred with them.\n\n* [Homo floresiensis](_URL_5_) is an odd Homo species found only on a single Indonesian island. This species likely evolved from a Homo erectus population. They evolved around 100,000 years ago and lived until quite recently, between 12-13,000 years ago. Humans very likely never encountered floresiensis, although it is conceivable that early human migrants to S.E. Asia may have met them.\n\n* Humans (Homo sapiens) evolved about 200,000 years ago in Africa from a population of H. heidelbergensis. Humans left Africa about 60,000-100,000 years ago. We were not the first species to leave Africa and when we left Africa we found that it was already occupied. Humans first encountered Neanderthals in Europe about 50,000 years ago.\n\n**TL;DR:** There are about two dozen or more species in the hominin lineage that link modern humans (Homo sapiens) to our last common ancestor with Chimpanzees and Bonobos which lived about 7 million years ago. ",
"We didn't evolve from monkeys, we're primates. So are [leumurs](_URL_1_) and they look nothing like [gorillas](_URL_0_) which are also primates. \n\nSpecies like the Neanderthals either died out or hybridized with humans. \n\nYou would be better off reading _URL_2_ \n\n",
"I'm gonna assume when you say monkeys, you mean primates, such as chimpanzees, human's closest cousin. The thing is we didn't evolve from chimpanzees or any other monkeys alive today. Rather, humans and other primates shared a [single ancestor](_URL_0_) from whom they both evolved. As you can see in the image, many came before the modern human who are not around anymore.",
"First, we didn't evolved from monkeys. We evolved from the common ancestors of monkeys and us. So to rephrase, why are there no transitional forms from those ancestors and us?\n\nThere are several.\n\nHomo erectus. \n\nHomo habilis\n\nHomo antencessor\n\nHomo neanderthalensis\n\nAnd our current form, Homo sapiens. And each time we find another skeleton, that fits in the profile, and is on different evolutionary ladder than us, or our ancestors. Then we come up with name, and insert it. But there are countless other ancestors, that had different shapes and forms that are lost to us. Simply because no skeleton stood the test of time. But you cannot find a direct link between one species, to another. It's like saying that latin speaking mother, gave birth to spanish speaking baby. It's all spanning hundreds of thousands of years, of gradual changes. There was never species from species direct one generational transition. If that's what you thought. ",
"I see a lot of answers here showing that ancestors in between us and primates existed, and there is an evolutionary chain leading up to humans. However, I'm not certain this answers OP's question. If you are asking why these in-between animals don't exist today, then the answer is because every time a new classification of primate evolved, they were equipped with better survival skills than their predecessor, and in the everyday competition for survival, eventually caused the predecessor to become extinct. This continually happened and now it is just us humans and primates. I assume primates didn't become extinct because the species that evolved directly from them had needs that did not conflict with the original primates.",
"All the other ones seem a little, \"ELI20\".\n\nSimply put, there is no \"between\" for us and monkeys. A few million years ago, we were all one thing, or one group of very similar things. In the intervening time, one group became modern humans, and other groups became modern apes (and lemurs, etc).\n\nSo there shouldn't really *be* anything in between. If you had a full human fossil record and a full chimp fossil record, you could trace it back far enough that they'd be the same, but after that point there is nothing but two different groups.",
"When we met people between us and apes (not monkeys, which are different), we did one (or both) of two things. We killed them. Or we screwed them.\n\nIf we killed them, then they no longer exist. If we screwed them, then they became part of \"us\".",
"Everyone has given straight up solid evidence that they did exist. \n\nBut I think the simple answer of why they don't exist today is that they would have to survive. \n\nLook at what people do to each other, now think about what humans would do to a different kind of person.\n\nIn all likelihood we killed them all off. ",
"Simple answer: **most species that have ever existed went extinct, by far**. So it's really not surprising that all of the species closely related to *homo sapiens sapiens* have gone extinct, because it's not an unusual situation. \n\nIf you look at evolutionary family trees you see this sort of situation very often. Think, for example, of the fact that birds are the only surviving dinosaurs. Here is a [graphic of the dinosaur family tree](_URL_3_). Of 13 groups shown in the diagram, all died off except birds.\n\nOr consider [the family tree of cynodonts](_URL_1_). In that tree, the only surviving branch is the [mammaliaformes](_URL_2_), which includes mammals and two other closely related but extinct groups. And mammals aren't just the only surviving cynodonts, they're the only surviving [therapsids](_URL_0_)!\n\nSo yeah, in the big picture, there's nothing surprising about humans being the only surviving hominids. ",
"Too many overcomplicated explanations here. It's actually quite simple:\n\n* Evolution doesn't state humans have evolved from apes, it states humans and apes have a common ancestor, which is completely different.\n\nSo in other words, at some point in time there existed **one living creature** (which scientists call \"the missing link\") which evolved in a number of different directions. One of these directions was what eventually became the human being, and another was what eventually became the Chimpanzee, for example.\n\nThis means, metaphorically speaking, as a species apes are not our parents, they are our siblings.",
"Well, let's say you're Danish and your family in Denmark goes back generations. If your great-great-great-great grandmother had a sister and they both had kids who had kids who had kids etc, you would have 4th cousins. If in those generations, one of your great-great-great aunts moved to Thailand and married a Thai man, you would have 4th cousins who were Thai. None of your other cousins might be, but an entire branch of the family would have a different racial and ethnic heritage than you. If all the people who knew the genealogy died without records of this happening, it would be weird to look at you and at your Thai 4th cousin and say, \"well, where's the connection?\" But genetic testing would show it, even though your common ancestor died many, many years ago.",
"I wouldnt think two intelligent and violent races could exist on this planet with out one interbreeding or killing off the other species. We have a hard enough time getting along with people who look like us (or slightly different).",
"The reason is the same reason why there is no species between a tiger and a lion.\nThey both have common ancestors. As speciation went on many species evolved, died out, evolved further, and until this day we have tiger and lion and some other species of the group Pantherinae.\nHumans and monkeys have the same ancestors, we did not evolve from some currently alive animal. ",
"I still cringe when I hear \"I believe in evolution.\" It exists whether you know about it or not.",
"If we're sticking to ELI5, I believe the answer breaks down to a simple two-part:\n\n- The gene pool has had hundreds of thousands of years to *continue* to diversify. The difference between n^99 and n^100 is *exponential* not incremental. And the more likely answer that human beings have a hard time swallowing is\n\n- We committed mass genocide or bred out our closest relatives, causing an apparent \"gap\" in similarity. It *astounds* me that this aspect is met with such an emotional denial. We are (by your own admission) animals, too. We have historical record proving that this tactic has been used time and time again by dictators and generals against our *own* Homo Sapiens Sapiens, and that's in *our* lifetime. Imagine non-verbal misunderstandings between rival packs/tribes.\n\nOr, if it helps, imagine we have an intelligent pack and a brute pack of pre-humans. The intelligent seek peace for lack of strength or aggression, but continue to come under attack/rape from the brutes. An intelligent toddler witnesses this, escapes to seclusion, finds a mate and breeds a pack that is raised in seclusion with its leader bent on survival or revenge. Who will he deem his biggest threat? What is the surest, most logical way to ensure that his litter won't be eradicated *ever again*? Why does this tactic sound so familiar?\n\nWe didn't start to catalogue our history until relatively recently, and we admit that it's only the winners in war who rewrite history. Humans denying committing mass genocide to better their reputation or avoid backlash? Noooooo, that could *never* happen ;)",
"Two species cannot occupy the same niche.\n\nLong story short, you can't have two species, such as homo sapiens and homo erectus, in the same place at the same time doing the same thing because one will be better and out-compete the other. \n\n-M.A. in Evolutionary Biology. "
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"https://en.wikipedia.org/wiki/Human_evolution"
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"https://en.wikipedia.org/wiki/Dinosaur_classification#/media/File:Evolution_of_dinosaurs_EN.svg"
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6gwh9u | what is the purpose of the holes in sink across from the faucet? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/6gwh9u/eli5_what_is_the_purpose_of_the_holes_in_sink/ | {
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"text": [
"They're another drain to prevent your sink from overflowing, if your main drain gets clogged up or is closed, and your faucet is open."
]
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||
343alr | why is the national guard used in riots? | Is just because of numbers or do they use different tactics than police use? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/343alr/eli5why_is_the_national_guard_used_in_riots/ | {
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"The National Guard has more and better equipment to deal with highly dangerous situations than local police/state troopers. They are also more likely to be seen as impartial in local conflicts, as cities cannot call for National Guard support themselves.",
"The National Guard is the strongest branch of law enforcement a state can muster. They are in a sense a militia under the direction of the states in peacetime. Most states use them as an outside arbiter in cases of riots.",
"The national guard is used at any point that the Governor requests their use. This is commonly done with riots when they need more numbers, and also for natural disasters. ",
"The regular Army and Reserves are under the control of the Federal Government, while the National Guard is under the control of BOTH the Federal Government and the State Government. That means it is the highest form of enforcement that the Governor can deploy with out asking for assistance from the Federal Government."
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34ebwl | how are electricity bills calculated? | I can't seem to understand the "estimated vs. actual" system. My bill this month was $15 and my bill last month was over $200. I called the company, and it's not a mistake. | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/34ebwl/eli5_how_are_electricity_bills_calculated/ | {
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"An estimated bill is based on their guess of how much electricity you'll use, while an actual bill is based on a real meter reading. What is your normal bill like? If last month's bill was estimated and the estimate was much too high, you'd get a much lower bill when they get an actual reading.\n\nSuppose that you really use about $107.50 of electricity per month. Last month they guessed that you'd use $200 and billed you. This month they got a real reading and discovered that you'd really used $215 over the two months. You've already paid $200, so they bill you the remaining $15.",
"So, there's a meter on your house. If it's a meter that someone has to come actually read, then sometimes they may estimate your bill so that they don't have to send someone to your house.\n\nWhat probably happened is that last month was an estimated bill. But your actual usage was considerably less than what they estimated -- so you overpaid. But this month, they sent someone to read the meter, and the difference between what was on the meter and what you'd already paid for was $15, so that's what you were billed for.",
"There are really two questions here 1) how is the bill amount calculated and 2) what is the difference between actual and estimated billing periods. \n\n\n.\n\n.\n\n1) For the vast majority of utilities the amount you are billed depends on two things, the energy you consume measured in kWh and the peak instantaneous usage you required measured in kW. kWh is a measure of energy and you pay a certain rate (typically around $0.10/kWh, depends on locale) for the energy that is transmitted to your house over the billing period and are usually labelled \"generation charges.\" kW is a measure of power, and is only an instantaneous measurement. The peak usage charge or demand charge depends on the peak usage your property had for one instant of the billing period. This is effectively saying that the utility has to be able to provide this many kW of power to your property at one time and had to be capable of providing that amount of power for the entire billing period, thus is charging you for that peak demand capacity. These two charges make the most of the billing amount with other taxes and fees that are typically derived from these two numbers. \n\n.\n\n.\n\n2) The actual and estimated billing periods are a little more interesting to talk about. It used to be that the utilities would have to send a worker to each meter to read the numbers and bill accordingly. To save money they would only do this every other month and would estimate the off months based on the previous reading and annual data. This is no longer the practice, most meters nowadays remotely send their data to the utility. Ever notice the metal boxes on a utility pole with a green or sometimes blue light? Those are collecting information from the meters in their area and sending that to the utility. Given this advancement in technology why do they still have the estimated and actual billing periods? This is far more complicated than I will explain here but should give an idea of what happens behind the scenes. Say you use $100 dollars worth of electricity in a given actual billing period, the next estimated billing period should be $100 right? One would think that but the utilities generally over charge on the estimated billing periods by say 10% so $110. So you and your 1,000 next door neighbors just gave them $10,000 for them to do whatever they please with, say invest in an account with 12% annual rate (easy numbers here) or 1% monthly. Over that next billing period they earn $100 from interest. Now when the next actual reading comes and they find that \"oppsie daisy\" we overcharged they are still coming out on top. Now these numbers sound very minuscule but when you take into account the hundred of thousands of customers that are serviced by the massive utilities these add up quickly and are built into the utilities business model. Taking into account actual fluctuations in consumer usages and prices for generation etc etc this gets very complex very fast. \n\n.\n\n.\n\n\nThat was quite long winded but I hope that explains what occurs with your utility bills every month. \n\n\nSource: Processing thousands of utility bills as an energy efficiency and renewable energy professional (Energy Engineer) "
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zftvi | genetically modified food | I hear a lot about this topic, but was it GM food to be precise? How is it created? Are there any large negatives/positives to consuming and growing GM food? Is it bad for the environment? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/zftvi/eli5_genetically_modified_food/ | {
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"It's created by artificially inserting genes into the genomes of the plants.\n\nThere are significant positives to GM food; it increases crop yields, can be used to insert useful nutrients, and can be made to require fewer or safer pesticides. Some people believe that GM food is more likely to be unhealthy than non-GM, but others disagree.\n\nGM food is not bad for the environment. People do disagree with this too, but unlike the situation with health concerns, there are no scientifically \nbacked environmental concerns about GM food.",
"Every living thing on earth has got DNA, which acts like an instruction manual for making life. Genes are bits of DNA which each make a specific tiny part of an organism.\n\nGM food is food that has some new genes added, or current genes removed or replaced with different versions from other living things. An example is having tomatoes which do not have genes which make them go rotten so they stay fresh for longer (Flavr Savr tomatoes).\n\nThe controversial GM crops are those which have genes that are responsible for getting rid of herbicides - large companies put these genes into plants and then sell them along with their specific herbicide in order to get more money!\n\nThe genes are put into plants by taking them out of other plants and into the new plants when they are only a few cells big (like a human baby embryo).\n\nIn general people are scared of GM because of misinformation, they do not understand that many of the things possible with GM can be potentially accomplished with regular breeding of good traits in plants - like you would with cows or racehorses.\n\nThere can be huge benefits with GM, like making rice called golden rice which contains vitamin A (necessary to be healthy) that a lot of people in rural areas in Asia do not get in their diet because of eating so much rice. Having vitamin A in the rice can make people be healthier. Also, plants can be changed so they produce much more grain/fruit than normal so that farmers either in developed or developing countries are able to get a lot more produce from the same area of land.\n\nHope this helps!\n\nEDIT: Changed 'pesticide' to 'herbicide' - thanks Mefanol"
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4alqvu | why do young girls seem to be more interested in performing arts than boys? is it cultural or psychological? | I act and sing, and I seriously notice that the number of girls in my school's programs have a much higher amount of girls than boys. Why is this? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/4alqvu/eli5_why_do_young_girls_seem_to_be_more/ | {
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"text": [
"Cultural, parents want male athletes and female stars, so they discourage any performing arts or anything of the sort in boys. It's really rooted in western culture, but I won't go completely Tumblr about it."
]
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[]
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|
1ooaog | the concept of modes (ionian, dorian, etc.) in musical theory. | I understand each note has various scales, minor, major, etc. and that various notes within that scale make a chord. And generally that a variant of a scale is used to achieve particular chords, diminished, augmented, etc. But that's where I get fuzzy... | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1ooaog/eli5_the_concept_of_modes_ionian_dorian_etc_in/ | {
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"For each note, there is a major, minor and various other altered scales. There are other scales for each note that are known as modes. Modes were actually the first types of scales before our modern major and minor scales.\n\nBasically it's taking a scale, but starting on a different note. For example take a C major scale :\nC D E F G A B C\n\nBy starting on C, it follows the pattern of whole steps and half steps our ears recognize as major. If I began the scale on D however, it would sound completely different. It would sound sort of \"minor-ish\". Playing from D to D in the key signature of C would yield what we call a Dorian scale. If I started on the E in scale of C instead, it would be called Phrygian, which is even cooler and weirder!\n\nBy starting in a different note within the major scale other than the tonic, you can make all the different modes. Where this comes into chords is more in jazz and contemporary music. A chord is usually the 1st, 3rd and 5th note of a scale. Many chords also include the 7th note as well. One of the most popular chords in modern music is the dominant seventh chord written like this C7 or D7. The dominant chord is the first, third, fifth and the seventh note of the scale that the chord is named for. However, in a dominant chord, the seventh note is lowered a half step. For example, a C7 chord would be C E G and Bb. This obviously doesn't fall in C major. You can either think of the chord as being a part of the key of F, or as being in C mixolydian.\n\nThis is a topic that I don't think I could fully explain to a five year old!! Please let me know if you have more questions."
]
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p5kvn | appellate courts | What are they used for and why? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/p5kvn/eli5_appellate_courts/ | {
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"This answer applies to the way Australian courts work. It probably translates fairly well to the USA & Canada, because each of their legal systems were influenced by that of the UK (and upon which Australia's legal system is built).\n\n\nAn appellate court is a court which hears appeals. If you go to court and lose, you can appeal the judge's decision in some circumstances. An appellate court may allow your appeal, and overturn the decision made by the lower court.\n\nThe first court to hear a case must answer two kinds of questions: questions of fact (if there is a jury, the jury makes findings on questions of fact) and questions of law. An example of a question of fact is \"how fast was the car going when it hit the pedestrian?\" An example of a question of law is \"was the driver negligent?\"\n\nIn Australia, most appeals are appeals on questions of law. This means that the person appealing the decision is arguing that the judge made a mistake in their legal reasoning. Generally, an appellate court will not review the findings of fact made by the lower court. This is because usually there are no witnesses testifying in appellate cases, and appellate courts think that the court which heard all the evidence, and saw all the witnesses being cross-examined, etc, is in a better position to decide what really happened. \n\nAppellate courts therefore mostly hear arguments on technical legal questions.\n"
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2qivl6 | why does my computer always need to restart or close the app i'm using to install an update? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2qivl6/eli5_why_does_my_computer_always_need_to_restart/ | {
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"Go for a drive in your car and replace some of the engine components while your at it. Basically the same concept.",
"Because it is modifying or replacing the code that writes the program. So, if you were to try and continue using the program while it is deleting important code that makes the program function, the program will stop working at one point because it has lost important code and the code that was going to replace it hasn't caught up with the deleted portion. With the gaps in the code, it cannot work properly anymore, therefore stopping or becoming corrupt.",
"In Windows, when a program is running, the executable file (.exe) is considered to be in use. The same goes for things like a document, like a picture in a photo editor. Likewise for extra code that sits outside of executables that many programs can share (.dll files). In Windows, modifying a file that is also in use is not allowed, so the operating system needs to postpone some of the update until a time when very few files are open.\n\nAsking the computer to shutdown has Windows forcefully close all programs, which frees up those .exes, .dlls, and open files. The time after everything's closed, and before the computer actually turns off is a great opportunity to run those postponed tasks. Another opportunity is right before the system starts up.\n\nBut this mainly applies to Windows and a handful of other operating systems that allow one program to prevent another from writing to a file. In another popular operating system, Linux, most files can be modified while they're in use: Whatever's using them will see the updates the next time the file is read. This is why in Linux, you can get away with installing most updates while the system is running.",
"This is one of the more commonly asked questions here, so I'm going to remove it. Please use the search bar and you'll find several answers to it. There's no rule against reposting questions, but please be sure to indicate that you've searched and haven't found your question listed. Thanks a lot."
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3dp6kk | i have always envisioned the universe as a sphere, but models picture it as flat constantly. why? | I have always thought that the big bang caused a spherical expansion of the universe and matter dispersed throughout the entire volume of this sphere, but my bedtime brain just started wondering why the space-time continuum is always drawn as flat. How does the concept of folding a flat space-time work when things are supposed to be dispersed in a 3D space? Hope that is clear as mud. Thanks!! | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/3dp6kk/eli5_i_have_always_envisioned_the_universe_as_a/ | {
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"Same reason we create models of the solar system or galaxy as flat - it's easier to model and visualize. In reality, the observable universe *is* a sphere, but the entire universe is likely infinite and thus doesn't have a shape. It may also be finite but unbounded, but again that doesn't lend itself to a specific shape.\n\n"
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8o5o2y | why are some murders a state crime but others a federal crime? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/8o5o2y/eli5_why_are_some_murders_a_state_crime_but/ | {
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"Murder is normally a state crime. It basically becomes a federal crime if the person murdered is a law enforcement officer, a federal government employee, if the murder involves drug trafficking, or if it is an act of terrorism.",
"murder is usually a state crime unless it’s one of the following: \n\nMultiple murders across state lines. \nmurder on a body of water. \nmurder for hire. \nmurder to influence the outcome of a trial. \nmurder of a federal elected or law enforcement official. \nmurder during a bank robbery. \nmurder of the immediate family member of a law enforcement official. \nmurder related to rape or child molestation. \nmurder by mail. "
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c6tdpt | how come when it's dark you don't see just black, you see what looks like tv static? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/c6tdpt/eli5_how_come_when_its_dark_you_dont_see_just/ | {
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"I personally don't experience this, it seems like it's a rare disorder. Might want to talk to your optometrist about it\n\n_URL_0_",
"Fun fact! Not everyone sees this. I asked my mom the same question when I was a kid. She knew what i was talking about but my dad thought we were both crazy. Turns out we have the very creatively named Visual Snow Syndrome. \n\nHere's some further reading.\n\n_URL_0_",
"I used to see this when I was doing psychedelics semi-regularly. It worked on blank walls too."
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||
1rhbap | what does "bonus" mean under the score on televised nba games? | I've had it explained to me before but I just don't get it. It has something to do with penalties. | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1rhbap/eli5_what_does_bonus_mean_under_the_score_on/ | {
"a_id": [
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"Normally, if you foul someone, they only get to take foul shots if they were already in the act of shooting the ball. If a team commits a certain number of fouls within a given part of the game, the other gets the bonus. When this occurs, they get to take foul shots if they are fouled even if the foul didn't occur during a shot. Note that both teams can have a bonus situation at the same time. "
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2d0cd2 | what do philosophers mean by we don't have free will? | I tried to understand the discussion on free will and I just don't get it at all. Please if someone can explain it in simple terms why do philosophers say that we don't have free will?
Is everyone not responsible for their own actions and thoughts? For example if I decide to donate to a charity, I could have also decided not to it was my conscious choice... right? Or is there another definition to free will that I'm not understanding? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2d0cd2/eli5_what_do_philosophers_mean_by_we_dont_have/ | {
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"Philosophers don't say that. Some do, and of those they say it for different reasons.\n\nA common idea against free will states we're just the product of our genetics and life experiences, and that if someone else had been born and lived exactly as you had they'd make all the same choices every time.\n\nWhether that's true is debatable. \n\n",
"Different philosophers have different reasons. Basically they are arguing that you did not make that choice to donate to charity, you only think you did. You were \"destined\" to make that choice. You will make all your \"choices\" based on outside factors that you can't control.",
" > For example if I decide to donate to a charity, I could have also decided not to it was my conscious choice...\n\nLet's examine this statement. Could you have decided not to? How do we know? What mechanisms resulted in your choice to donate? Presumably you'd donate because you believed it was a good cause, you consider donating a worthy expenditure of your money, you are willing to make the effort to see it done. \n\nNow, if we could somehow rewind time and let it play out again, these factors are all still there, all to the same degree. Is there any particular reason to believe you would perform a different action from the same initial state? Is there some 'roll-the-dice' mechanism attached to this decision, which can randomly affect the outcome regardless of the initial state? Or is your decision not really a decision, but purely the agglutinate result of pre-existing beliefs, themselves agglutinates of even more pre-existing beliefs, founded ultimately from inputs you have received throughout your life and the chemistry of your brain?\n\nIn essence, did you really make a choice or did you do what you would do every time given the exact same circumstance?",
"The argument is actually based in physics. Physics has the concept of \"Newtonian determinism\". This basically says, if you have complete knowledge about the variables in a physical state, then you can predict from the laws of physics exactly what that state will be like at any point in the future. But that means it HAS to end up in that state, because the laws of physics require it. So there can't be any free will choice in the middle to do something different. In this idea, we only appear to be making choices, but the claim is that every single \"choice\" is really determined by the laws of physics acting on us, on our brains, on our interactions with others, from the conditions in the previous moment."
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83cysc | how is linear algebra used in machine learning algorithms? | Edit: the two well thought out and informative answers I've gotten so far are making me very glad that I chose electrical engineering instead of computer engineering for a major | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/83cysc/eli5_how_is_linear_algebra_used_in_machine/ | {
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"We use matrices to represent data and relationships between data. We do all kinds of matrix stuff; we multiply them, add them, find covariance, find eigenvectors etc. Multiplying two matrices with say 1000 entries each helps *relate* 2000 units of data in just one operation, multiplication. Matrices make organization in ML easy. Operations just work if you know the algorithm. For a Machine Learning student, matrices are just a way to list stuff basically, but if you can understand the mathematical implication behind matrices and how they affect space, aka Linear Transformations, and other Linear Algebra intuitions, like what exactly are you doing to your data units when you find their eigenvectors, it can help you understand your ML algos better. Other than this, ML tools have highly optimised algos for matrices and if you were to use normal non matrix operations, it'll be much slower. These are the main reasons I think Linear Algebra is used in ML. ",
"Many machine learning algorithms, like neural nets, can be represented by what is known in computer science as a [graph](_URL_0_). A graph is a series of connected nodes, and each connection is assigned a weight, representing some sort of cost or effort associated with moving between those nodes. \n\nInternally, a graph with N nodes can be represented as an N x N matrix. Each row and column represents a node, and the values in the matrix show whether the nodes are connected and what the weight of the connection is. If M is that matrix, if node 1 and node 5 are connected with a weight of 20, then M[1,5] = 20.\n\nRepresenting a graph in this way means that performing operations on that graph is equivalent to matrix arithmetic. Computers are very good an linear algebra, and there are many very efficient, time test algorithms you can use to peform these sorts of calcuations quickly.",
"__How (as in for what) do we use it?__ \n\nAs a tool to make it easier to communicate with each other. \n\nHow does that make it any easier? Because it makes communication shorter, more specific and less error prone. Example: 2 * 2 + 3 * 3 + 4 * 4 + 5 * 5 vs [2,3,4,5]^2 . Nobody wants to read (or write) a 30 page document if you can do the same in 3 pages.\n\n__How (as in where) do we use it?__\n\nWhenever we can make something more concise by using it. Basic linear algebra is concerned with vector spaces and their properties, so every time you have a countable number of \"features\" (dimensions) that can be used to describe an object, linear algebra is your guy to help you say more with less (space, words, characters, ...) . \n\nIn Machine learning we tend to describe a single record in a dataset as \"It has this property and this property and this property and ...\", so as a countable number of features. \n\nSo with our basic building block perfectly made for linear algebra, it should be easy to conclude that it is used almost everywhere."
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bmjui8 | why people still buy iphones even if android phones are useable and cheap? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/bmjui8/eli5_why_people_still_buy_iphones_even_if_android/ | {
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"Lol you ready for this. You ain't ready for this. And I'll join by saying more users on reddit are android users.",
"They work.\n\nExample - I was once in a car with three other attorneys on a way to a meeting for which we needed to review about 20 pages of new documents. I had an iPhone and all three other attorneys had Android phones issued by their law firms.\n\nWe were driving through a desert area with spotty cell service, but the e mailed documents came through on my phone HOURS before they showed up on the Androids. We had one of the attorneys read the changed pages to get our negotiations done before we got to the client.\n\nIn situations where dependability is the most important thing, the iPhone is superior.",
"iPhones are ridiculously overpriced, but they work.\n\nAlso, Androids don’t have Genius Bars where you can get help when something doesn’t work.\n\nAs someone who travels a lot, and deals with a ton of information created on different platforms, i think it’s easier to manage.\n\nIf you don’t need all that, you would just have to decide whether the price is worth it.\n\nI have a cousin who travels internationally every week as a pilot, and uses his phone for private functions. \n\nHe swears by his Galaxy."
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8ixkal | how police officers turning off their body cameras don't count as evidence tampering. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/8ixkal/eli5_how_police_officers_turning_off_their_body/ | {
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"Three reasons: first, the prosecutor has to decide whether or not to charge a crime. Many prosecutors are reluctant to charge crimes against cops because they need cops on their side to prove a case. You get a cop who is pissed off at you? Suddenly he “can’t remember” the drug case you’re prosecuting, or isn’t available to testify, and you lose your case. There is immense pressure to play nice, and that means looking the other way. \n\nSecond, officers are often immune from being punished for their actions. That’s because the question isn’t “what would a reasonable person do under X circumstances,” it’s “what would a reasonable OFFICER do?” This is how they are not convicted of homicide under circumstances that arguably show straight-up execution; they are held to a different standard than civilians. \n\nThird, and related: nearly every crime requires an intent element. To show evidence tampering, you’d have to prove a criminal intent - something that is difficult to do if you’re not able to prove the underlying wrong. \n\nThis is my first time replying to ELI5, so I hope I did okay :) \n\nSource: I’m a career public defender ",
"How does a \"public defender\" not answer the Q asked but rather speculates on intent?\n\nTo tamper with evidence requires the evidence *exist*. If no video is taken, there is no evidence to tamper. \n\nSecond, those cameras aren't on all the time for many very justifiable reasons. Anything they record can and should be public record. **Unedited**. Think about that next time you use the bathroom or console a CPS case. Since they go on and off, you cannot dictate when they go on. It can be a policy but not a law as that requires clairvoyance. \n\nI speculate the \"public defender\" didn't discuss these as the tactic he would use is to exploit them to get his client off. \n\n",
"I said this on the original article\n\nPolice have to have the ability to turn the cams off while on break...going to the bathroom or when theres simply no need. Not to mention the logistics. The city cant record 11 hours ( length of a typical officer shift) straight of video for ever officer, thats crazy expensive to retain in a lot of states if not flat out impossible. You would need a google level server for a mid city city especially since some states require retention for decades, a lifetime or forever. They way most dash cams and body cams work, is they are always technically on, but when activated they record 15 minutes or prior to being activated and continue to record.\n\nEdit: turning off a cam during an incident may be a violation of policy and thus subject an officer to discipline but might not be destructive of evidence because its failure to produce evidence rather than destruction since didnt exist then was destroyed. Plus you first have to prove a crime occurred first. \n\nSource: worked in LE, including public discourse and police data retention."
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4luw2l | how are we given life span estimates for some electronic components which claim to have an incredibly long life span? | In regards to this: _URL_0_
How is it researchers can claim this to be able to store data safely for 14 billion years when that amount of time hasn't even passed on earth yet? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/4luw2l/eli5_how_are_we_given_life_span_estimates_for/ | {
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"Researchers do stress test.\n\nExample... So they make the hardware work at 100% power and utility for long periods of time. lets say transfer 360tb data in to the drive then delete it and transfer it into the drive again, and they do this over and over again until the drive dies. But chances of real users doing that your normal computer is rare.\n\nThen using some equations like Time for drive to die + data transfer total then compare to like an average hdd averages that they might have. they can reach that conclusion of 14 billion years.\n\nedit: speeling",
"There's a difference between a *scientific* estimate and an *engineering* estimate.\n\nA scientific estimate (as this is) is based on a narrow set of idealized parameters. It's equivalent to saying \"a feather and a brick drop at the same speed\" - which is true, if you ignore every thing except for mass and the force of gravity. My suspicion (without a thorough knowledge of the underlying technology) is that this storage method is not self-interfering. That is, unlike magnetic media, the presence of data in one place on the medium does not potentially degrade the data on another part. So if you had some theoretically perfect vacuum chamber that would remain forever isolated from the rest of the universe, your data would remain indefinitely.\n\nAn *engineering* estimate is based on the likely performance in real world scenarios. Most of the time when you buy a consumer product, longevity is based on an engineering estimate because you're not planning to use it in a perfectly isolated containment unit. You're also going to need to deal with real world problems (such as the fact that while your media may well last until the heat death of the universe, it's unlikely that whatever reads that media will still be in commercial production at that point).\n\nSo your question is really \"how can an engineer make that claim?\" when the answer is \"an engineer didn't make the claim - a scientist did\"."
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296029 | why can't i fall asleep on my back, but i wake up laying on my back sometimes? | I wish I could fall asleep on my back. | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/296029/eli5_why_cant_i_fall_asleep_on_my_back_but_i_wake/ | {
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"You roll over in your sleep.",
"I too have the same problem. \nNot long ago I found out that when I was a baby my mother would lay me down on my stomach when putting me to sleep. She was told that babies are more likely to choke on spit-up and whatever weird liquids are going on in a babies face (Nowadays parents are told that babies are better off sleeping on their backs). \nI've always wondered if the reason I couldn't sleep on my back is because my mother insisted on me sleeping on my stomach.",
"I personally feel more vulnerable on my back. My face and squishy parts are exposed. If I'm face down I protect all that."
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6fhxg7 | what is the difference between christianity, islam, and judisim | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/6fhxg7/eli5_what_is_the_difference_between_christianity/ | {
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"IIRC. Reading an Islamic brochure while waiting for class at UNI a few years back I remember them specifically point out that Jesus was not the son of god but a prophet. That god is not man or woman so would not have had a child.\n\nThat's all I got.",
"I mean, there are a lot of differences.\n\nThey all share some background, with the newer two (Islam and Christianity) sharing much dogma in common with the older one (or two, in the case of Islam). \n\nOne of the biggest things that separates Judaism from the other two is that Jews don't attempt to convert others to their faith and, even to this day, most Jews or people of Jewish descent (e.g. me) can trace their heritage (for the most part) back to particular Jewish ethnic groups.\n\nIslam is most different from the other two because even in its earliest days it was a political system as well as a religious one. Jesus, for example, was never a political leader, but from his earliest days as a religious leader, Muhammad was also leading a polity.\n\nAs I said, there are tons and tons of differences and a lot of similarities between the three, large and small. A reddit thread isn't going to cover it all.",
"They're all monotheistic Abrahamic (they all trace their physical/spiritual lineage back to Abraham) religions. \n\nJudaism is an ethnoreligion meaning that there is a genetic and cultural component involved in being a Jew (although converts are accepted). Judaism is also very ritualistic and adherence to the Law is the standard mode of practice. Salvation and faith are relatively unimportant, and some branches do not even believe in an afterlife, so the Law is practiced for its own merit/because God commanded it, not necessarily for reward.\n\nChristianity believes in the Old Testament (Jewish holy book) as true, but believes that the Law of Moses was made null and void with the death of Jesus. Now with death defeated by Jesus' sacrifice, the average layman can also circumvent death and obtain eternal life by having faith in Jesus. Whether or not your actions are important to salvation or not is a hotly debated topic in Christianity, but the consensus I see is that faith is all that is needed for salvation, but a truly held faith manifests outwardly in the form of upstanding behavior. Most Christians also believe that Jesus is not only a prophet, but God the Son himself (not merely a third of God, but fully powerful and omniscient, yet able to act independently of the other two Persons of the Godhead. Also, don't see this as 3 gods either. The philosophy is very interesting imo).\n\nIslam is where my expertise is the weakest. Muslims believe that Jesus was a prophet and will return on the second coming, but he was not divine nor God. Islam as far as I can see values both the Law and faith as important. Islam is also a self-contained political system, which combined with the incentive to convert others, makes for a very powerful and fast growing religion. They believe that Muhammad was God's last prophet and most of the morality of Islam is based upon following the example of him. The Jewish and Christian bibles are considered to be mostly true, but corrupted over the years and the Quran is therefore the only true source of divine knowledge (And therefore the only holy book).\n\n"
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julep | how the ipod to cassette player things work. | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/julep/how_the_ipod_to_cassette_player_things_work/ | {
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"First some theory about magnetism:\n\nTake a piece of fine copper wire and wrap it around a pencil neatly until the whole pencil is covered with a single layer of wire. Connect the two ends of that wire to a volt meter. Now wave a magnet back and forth across the surface of the wire and you will see the volt meter wiggle in direct correlation to the magnet. If you wiggle in small strokes, the needle moves small distances. If you go fast and wide the needle will also go fast and wide. This simple principle of electromagnetism is the basis of analog audio.\n\nIn a vinyl record the analog audio is recorded as tiny grooves on the surface of the record which wiggle a delicate needle. These wiggles are \"heard\" in the exact same way the volt meter \"heard\" the magnet in your hand wiggling across the copper wire in terms of amplitude (volume) and frequency (how fast/slow you wiggle).\n\nIn a cassette tape you don't have groves and needles that wiggle. Instead what you have is magnetic tape which passes over a sensitive tape head in the tape player and this player can detect variances of magnetic force going towards or away from the head. \n\nBy \"towards or away\" what I mean to say is North or South. Magnets and materials that can be magnetically charged have poles which oppose each other in terms of direction. You wave your magnet across the pencil in one direction, the volt meter registers perhaps a positive charge. Wave it in the opposite direction and it registers a negative/opposite charge. In real life these wiggles are happening in the 10's of thousands of times per second, producing sound, and this is essentially what is stored on a magnetic tape cassette.\n\nIn a converter, there is no magnetic tape. Instead there is a magnetic head that is just like the head in side your tape player, but flipped and made to act like a recording head would (where it exerts a magnetic force instead of passively listening for one). The magnetic force it puts off come directly from the audio voltage wiggles that your iPod produce and normally would send to your ears through earbuds, but in this case the audio voltage is going to that head, meeting directly with the listening head in the tape player.",
"So a regular cassette uses a magnetic ribbon to store the information of a song, wound onto spools. The adapter has a belt of that that continuously spins. There is a writer in the cassette to convert the electric signals in the wire to a magnetic field, which is written on the ribbon belt, and read by the cassette player in the stereo.",
"To understand how those work you first need to understand how a regular cassette tape works. \n I don't know for certain, but here's my understanding of it: Cassettes work because of a special ribbon inside of it. This ribbon is able to hold song information almost like a record or a CD. A cassette player is able to read this information and play it on your speakers. \n \n Now for the mp3 cassette players: The player works almost exactly like a regular tape. What makes it special is that instead of using a very long ribbon, it uses a small electronic piece that can fool the cassette player into thinking it's part of the ribbon. This small electronic piece takes the information your mp3 player puts out and changes it to something a cassette player can read. \n \nIf I'm incorrect, then let me know. This is just how I've always understood them to work.",
"A regular cassette has a long piece of tape inside it. At the factory, the people who make the cassette use a magnet to put special magnetic symbols on the tape - a bit like an invisible alphabet. When you put the cassette in the stereo, the stereo winds the spools on the cassette so that the tape goes past a part of the stereo which can read the invisible message which has been written on the tape. The stereo then uses these instructions to tell the speakers what to play.\n\nWith an iPod cassette adapter, instead of a piece of tape, there is just a thing called a magnetic head. It's connected to the iPod the same way as your headphones are, except instead of turning the signals from the iPod into sound, it converts them into the special language which the used by a regular cassette to talk to a stereo. It then flashes those instructions at the stereo - a bit like showing a person a series of flash cards with one word at a time on them, instead of a piece of paper with writing. But because the stereo can only see one piece of writing at a time anyway - it's not clever, like people are - it can't tell the difference, and just thinks its a regular cassette telling it what to play. \n\nFWIW, I thought diablo75's was better (though still oversimplified). if everyone is going to restrict themselves to the level of understanding a five year old could reasonably attain, nothing is ever actually going to be explained - the ideal ELI5 seems to be an explanation which tells you very little while leaving one with the feeling of having understood something.",
"C'mon guys, this isn't hard, and almost everyone but Diablo75 is wrong in some way.\n\nThe only thing in one of those mp3 tapes is a wound length of wire.\nJust like in the original explanation waving a magnet over a wire causes an electric signal to be made. You can do the opposite too though, by putting an electric signal into the coil of wire you make the wire emit a magnetic signal. The mp3 cassette does just this, turns a electric signal (from your mp3 player) into a magnetic signal for the tape deck. The tape deck also has a wound length of wire that picks up the magnetic signal and turns it back into an electric one that speakers can turn into sound.\n\nA regular cassette's tape is a really long weak magnet that varies in strength to hold an audio signal. When the tape is passed in front of the tape deck head (simply a coil of wire) the magnetic signal is turned into an electrical one.\n\nYou see? Nothing to it, just wire/electricity, and physics takes care of everything for you.",
"\"iPod\" to cassette player? LOL. You kids!",
"*I tried to write this in such a way that I never have to talk about magnetism like diablo75 did* \n \nThis takes some background info first: \n \nIf I push you, you move backwards. If I pull you, you come towards me. If I grab your shoulders and start making you go back and forth, you start to wiggle. Sound is actually doing the same pushing and pulling to your ears. Your ears feel the pushing and pulling and recognize different wiggles as different sounds.\n \nA sound recording is a written copy of a sound wiggle someone made already. You can color a picture on a piece of paper and I can see the picture later. The same is happening with an ipod - someone wrote down sounds so we can hear them later. The ipod is a place to put these written sound wiggles for later. It is just like when I store the pictures you draw on the refrigerator or in your picture books. We can go back later and look at them. \n \nThe ipod itself can't read back the sound, just like your books can't read themselves to you. Something has to read the ipod and tell us what is in it. That's what a speaker is for. The speaker is a thing that can read back the written wiggles and turn them into wiggles we can hear with our ears.\n \nFor the speakers to be able to read what is written inside the ipod, we have to plug the speakers into it. But in an old car, we have a problem. The speakers in the car are old and don't know how to read the ipod. They only know how to read off of a cassette tape which is a very old way of writing down sound wiggles. Since the cassette tape and the ipod are written differently, we have to have something that can read an ipod and write like a cassette tape at the same time. This is what we use the cassette adapter for - it can do both those things at the same time. It reads the ipod and then writes the sound in the cassette language which the speakers can then read. Now that they can read the sounds, they are able to shake your ears so that you know what was written on the ipod.\n \n-------------------------- \n \nNow to the original question, how does the adapter work (like I'm five): \n \nIf you're reading a book, you are only reading one word at a time even though the page is covered in words. You read one, and then move to the next one as you move across each line and down the page. If I were to copy a page of a book onto separate pieces of paper one word at a time, I could show you them in the right order and you'd still be able to read the story because I showed them to you in the same order they were written on the page. \n \nLikewise, if I taped all the separate words of your story together in a very long strip of paper and pulled the paper across your desk, you could read the story one word at a time as the words passed in front of you. \n \nSpeakers read sound the same way you read a book. They only read one thing at a time and then move on to the next one. An old cassette tape has all the sound wiggles written in a very very long strip, and the speakers read the sound wiggles one at a time as they pass in front of them. The speakers are not allowed to skip ahead, because they can only see the one sound in front of them on the long strip. \n \nan Ipod has the sound written like a page out of a book. All the sound is there as one big page and newer speakers that can be plugged right into the ipod can read the wiggles of any part of the song it wants because it can skip around the page. The old cassette tape speakers don't know how to do this because they were only ever taught how to read one single sound wiggle at a time. They must rely on something else to read the ipod for them and then tell them what it says. \n \nThe cassette player adapter can read any part of the ipod's written sound, but it can't turn what it reads into sound for us to hear. It only has the ability to rewrite it one sound wiggle at a time so that the cassette speakers can then read that sound and make the noise. \n \nThe biggest difference is that it doesn't write it down on something permanent like paper. It writes it once for the cassette speaker to see and then immediately erases the sound and moves on to the next one. \n \nIt's almost as if the adapter had a chalk board held up in front of the cassette speakers and was copying the ipod sound wiggles one at a time.",
"Magnets.\n\nNo really.",
"This can't be explained to a 5 year old. This belongs in /r/answers. Downvoted. ",
"Five year olds don't know what cassette players are :(",
"I came here for a fucking explanation LIKE I'M FIVE GOD DAMNIT",
"First some theory about magnetism:\n\nTake a piece of fine copper wire and wrap it around a pencil neatly until the whole pencil is covered with a single layer of wire. Connect the two ends of that wire to a volt meter. Now wave a magnet back and forth across the surface of the wire and you will see the volt meter wiggle in direct correlation to the magnet. If you wiggle in small strokes, the needle moves small distances. If you go fast and wide the needle will also go fast and wide. This simple principle of electromagnetism is the basis of analog audio.\n\nIn a vinyl record the analog audio is recorded as tiny grooves on the surface of the record which wiggle a delicate needle. These wiggles are \"heard\" in the exact same way the volt meter \"heard\" the magnet in your hand wiggling across the copper wire in terms of amplitude (volume) and frequency (how fast/slow you wiggle).\n\nIn a cassette tape you don't have groves and needles that wiggle. Instead what you have is magnetic tape which passes over a sensitive tape head in the tape player and this player can detect variances of magnetic force going towards or away from the head. \n\nBy \"towards or away\" what I mean to say is North or South. Magnets and materials that can be magnetically charged have poles which oppose each other in terms of direction. You wave your magnet across the pencil in one direction, the volt meter registers perhaps a positive charge. Wave it in the opposite direction and it registers a negative/opposite charge. In real life these wiggles are happening in the 10's of thousands of times per second, producing sound, and this is essentially what is stored on a magnetic tape cassette.\n\nIn a converter, there is no magnetic tape. Instead there is a magnetic head that is just like the head in side your tape player, but flipped and made to act like a recording head would (where it exerts a magnetic force instead of passively listening for one). The magnetic force it puts off come directly from the audio voltage wiggles that your iPod produce and normally would send to your ears through earbuds, but in this case the audio voltage is going to that head, meeting directly with the listening head in the tape player.",
"So a regular cassette uses a magnetic ribbon to store the information of a song, wound onto spools. The adapter has a belt of that that continuously spins. There is a writer in the cassette to convert the electric signals in the wire to a magnetic field, which is written on the ribbon belt, and read by the cassette player in the stereo.",
"To understand how those work you first need to understand how a regular cassette tape works. \n I don't know for certain, but here's my understanding of it: Cassettes work because of a special ribbon inside of it. This ribbon is able to hold song information almost like a record or a CD. A cassette player is able to read this information and play it on your speakers. \n \n Now for the mp3 cassette players: The player works almost exactly like a regular tape. What makes it special is that instead of using a very long ribbon, it uses a small electronic piece that can fool the cassette player into thinking it's part of the ribbon. This small electronic piece takes the information your mp3 player puts out and changes it to something a cassette player can read. \n \nIf I'm incorrect, then let me know. This is just how I've always understood them to work.",
"A regular cassette has a long piece of tape inside it. At the factory, the people who make the cassette use a magnet to put special magnetic symbols on the tape - a bit like an invisible alphabet. When you put the cassette in the stereo, the stereo winds the spools on the cassette so that the tape goes past a part of the stereo which can read the invisible message which has been written on the tape. The stereo then uses these instructions to tell the speakers what to play.\n\nWith an iPod cassette adapter, instead of a piece of tape, there is just a thing called a magnetic head. It's connected to the iPod the same way as your headphones are, except instead of turning the signals from the iPod into sound, it converts them into the special language which the used by a regular cassette to talk to a stereo. It then flashes those instructions at the stereo - a bit like showing a person a series of flash cards with one word at a time on them, instead of a piece of paper with writing. But because the stereo can only see one piece of writing at a time anyway - it's not clever, like people are - it can't tell the difference, and just thinks its a regular cassette telling it what to play. \n\nFWIW, I thought diablo75's was better (though still oversimplified). if everyone is going to restrict themselves to the level of understanding a five year old could reasonably attain, nothing is ever actually going to be explained - the ideal ELI5 seems to be an explanation which tells you very little while leaving one with the feeling of having understood something.",
"C'mon guys, this isn't hard, and almost everyone but Diablo75 is wrong in some way.\n\nThe only thing in one of those mp3 tapes is a wound length of wire.\nJust like in the original explanation waving a magnet over a wire causes an electric signal to be made. You can do the opposite too though, by putting an electric signal into the coil of wire you make the wire emit a magnetic signal. The mp3 cassette does just this, turns a electric signal (from your mp3 player) into a magnetic signal for the tape deck. The tape deck also has a wound length of wire that picks up the magnetic signal and turns it back into an electric one that speakers can turn into sound.\n\nA regular cassette's tape is a really long weak magnet that varies in strength to hold an audio signal. When the tape is passed in front of the tape deck head (simply a coil of wire) the magnetic signal is turned into an electrical one.\n\nYou see? Nothing to it, just wire/electricity, and physics takes care of everything for you.",
"\"iPod\" to cassette player? LOL. You kids!",
"*I tried to write this in such a way that I never have to talk about magnetism like diablo75 did* \n \nThis takes some background info first: \n \nIf I push you, you move backwards. If I pull you, you come towards me. If I grab your shoulders and start making you go back and forth, you start to wiggle. Sound is actually doing the same pushing and pulling to your ears. Your ears feel the pushing and pulling and recognize different wiggles as different sounds.\n \nA sound recording is a written copy of a sound wiggle someone made already. You can color a picture on a piece of paper and I can see the picture later. The same is happening with an ipod - someone wrote down sounds so we can hear them later. The ipod is a place to put these written sound wiggles for later. It is just like when I store the pictures you draw on the refrigerator or in your picture books. We can go back later and look at them. \n \nThe ipod itself can't read back the sound, just like your books can't read themselves to you. Something has to read the ipod and tell us what is in it. That's what a speaker is for. The speaker is a thing that can read back the written wiggles and turn them into wiggles we can hear with our ears.\n \nFor the speakers to be able to read what is written inside the ipod, we have to plug the speakers into it. But in an old car, we have a problem. The speakers in the car are old and don't know how to read the ipod. They only know how to read off of a cassette tape which is a very old way of writing down sound wiggles. Since the cassette tape and the ipod are written differently, we have to have something that can read an ipod and write like a cassette tape at the same time. This is what we use the cassette adapter for - it can do both those things at the same time. It reads the ipod and then writes the sound in the cassette language which the speakers can then read. Now that they can read the sounds, they are able to shake your ears so that you know what was written on the ipod.\n \n-------------------------- \n \nNow to the original question, how does the adapter work (like I'm five): \n \nIf you're reading a book, you are only reading one word at a time even though the page is covered in words. You read one, and then move to the next one as you move across each line and down the page. If I were to copy a page of a book onto separate pieces of paper one word at a time, I could show you them in the right order and you'd still be able to read the story because I showed them to you in the same order they were written on the page. \n \nLikewise, if I taped all the separate words of your story together in a very long strip of paper and pulled the paper across your desk, you could read the story one word at a time as the words passed in front of you. \n \nSpeakers read sound the same way you read a book. They only read one thing at a time and then move on to the next one. An old cassette tape has all the sound wiggles written in a very very long strip, and the speakers read the sound wiggles one at a time as they pass in front of them. The speakers are not allowed to skip ahead, because they can only see the one sound in front of them on the long strip. \n \nan Ipod has the sound written like a page out of a book. All the sound is there as one big page and newer speakers that can be plugged right into the ipod can read the wiggles of any part of the song it wants because it can skip around the page. The old cassette tape speakers don't know how to do this because they were only ever taught how to read one single sound wiggle at a time. They must rely on something else to read the ipod for them and then tell them what it says. \n \nThe cassette player adapter can read any part of the ipod's written sound, but it can't turn what it reads into sound for us to hear. It only has the ability to rewrite it one sound wiggle at a time so that the cassette speakers can then read that sound and make the noise. \n \nThe biggest difference is that it doesn't write it down on something permanent like paper. It writes it once for the cassette speaker to see and then immediately erases the sound and moves on to the next one. \n \nIt's almost as if the adapter had a chalk board held up in front of the cassette speakers and was copying the ipod sound wiggles one at a time.",
"Magnets.\n\nNo really.",
"This can't be explained to a 5 year old. This belongs in /r/answers. Downvoted. ",
"Five year olds don't know what cassette players are :(",
"I came here for a fucking explanation LIKE I'M FIVE GOD DAMNIT"
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2p0mb6 | why is my graphics card so big compared to my cpu? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2p0mb6/eli5_why_is_my_graphics_card_so_big_compared_to/ | {
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"Your graphics card has it's own RAM. Your CPU's RAM is on the motherboard. Technically you're counting the GPU, it's board, and RAM, and cooling stuff as one thing. So if you do that with the CPU too, the CPU is much bigger since its board is the motherboard. ",
"Your graphics card isn't just a processor. It has its own memory, cooling, and of course the GPU. It's like a mini computer inside your computer. ",
"Modern cards have the graphics chip, memory, and cooling all compacted into the card. A big bulk of that size is actually the cooling, as the board gets quite hot during use."
]
} | [] | [] | [
[],
[],
[]
] |
||
63cx50 | why do we have different tastes in what we like or don't like? why couldn't we all just have the same tastes? | [deleted] | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/63cx50/eli5_why_do_we_have_different_tastes_in_what_we/ | {
"a_id": [
"dft4vpu"
],
"score": [
2
],
"text": [
"There are a large range of [olfactory receptors in the human population](_URL_0_).\n\n > Using sophisticated mathematical modeling to extrapolate results, researchers predict that the olfactory receptors of any two individuals differ by about 30 percent. This means that for any two randomly chosen individuals, approximately 140 of their 400 olfactory receptors will differ in how they respond to odor molecules.\n\nThis means that your actual physical sensors are different, and trigger from different things. This means most people will taste things differently from each other, and perceive different things are nice or nasty.\n\nEvolutionary, it doesn't really matter if you find rocket to taste horrible, since there is no benefit nutritionally from eating it. However, if you find something which is poisonous to taste good, then you will be eliminated from the genepool. This selection pressure means that tasting harmless chemicals as nasty is common, and people will dislike things that others like."
]
} | [] | [] | [
[
"https://www.sciencedaily.com/releases/2013/12/131208133402.htm"
]
] |
|
ussvw | why does an opened bottle of coke go "flat" faster if it is stored in a fridge? | I've noticed that after opening a bottle of Coke, it loses it's carbonation more quickly if it is stored in the fridge as opposed to being kept outside at room temperature. To clarify, I am talking about the bottle being stored with the cap back on. Why does this happen? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/ussvw/eli5_why_does_an_opened_bottle_of_coke_go_flat/ | {
"a_id": [
"c4y9qcp"
],
"score": [
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],
"text": [
"The feeling of carbonation on your tongue is due to dissolved carbon dioxide coming out of solution and forming bubbles on your tongue. When they carbonate drinks, carbon dioxide is pumped under high pressure into the drink. This causes the drink to be supersaturated with carbon dioxide.\n\nSaturation is the point where the drink can not hold any more carbon dioxide. The manufacturing process manages to go past this point and make more carbon dioxide dissolve in the drink. The result of this is that when the drink is agitated (by bumping or shaking it) or a rough object (like your tongue) is exposed to the drink, the carbon dioxide in the supersaturated coke rush out of the coke by forming bubbles, resulting in the \"fizzy\" feeling.\n\nThe higher the temperature of the coke, the less carbon dioxide can be dissolved in it. So when you place your coke in the fridge, it would be able to hold more carbon dioxide when it cools down, meaning it would stop being supersaturated. Remember that the reason bubbles rush out of the drink to give that fizzy feeling is due to supersaturation, but now the cold coke isn't supersaturated and will feel \"flat\".\n\nAn interesting thing to note is that the \"fizzy\" warm drink you left on the counter actually has less carbon dioxide dissolved in it than the \"flat\" cold drink you left in the fridge. It only feels more fizzy because the carbon dioxide wants to escape from it by forming bubbles."
]
} | [] | [] | [
[]
] |
|
fcutvq | when to use use to vs. used to. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/fcutvq/eli5_when_to_use_use_to_vs_used_to/ | {
"a_id": [
"fjd3iga"
],
"score": [
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],
"text": [
"I'd always use \"used to\", but American usage seems to prefer \"use to\" in negatives and questions, when using the past tense of any other verb would sound wrong:\n\n- I *used to* be a fan of Mitch Hedberg.\n- Did you *use to* be a fan of Mitch Hedberg?\n- I didn't *use to* be a fan of Mitch Hedberg?\n\nComparing that to \"I wanted to...\", you'd always say \"did you want to...\" and \"I didn't want to...\" rather than \"did you wanted to...\" and \"I didn't wanted to...\""
]
} | [] | [] | [
[]
] |
||
61pci0 | assuming humans are still alive at the time, how close will andromeda have to be to the milky way before we notice changes such as gravity, weather, and other stuff. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/61pci0/eli5_assuming_humans_are_still_alive_at_the_time/ | {
"a_id": [
"dfg8vxo"
],
"score": [
3
],
"text": [
"Based on current calculations astrophysicists predict a 50% chance that in a merged galaxy, the Solar System will be swept out three times farther from the galactic core than its current distance. They also predict a 12% chance that the Solar System will be ejected from the new galaxy sometime during the collision. Such an event would have no adverse effect on the system and the chances of any sort of disturbance to the Sun or planets themselves may be remote.\n\nExcluding planetary engineering, by the time the two galaxies collide the surface of the Earth will have already become far too hot for liquid water to exist, ending all terrestrial life; that is currently estimated to occur in about 3.75 billion years due to gradually increasing luminosity of the Sun (it will have risen by 35–40% above the current luminosity).\n\n_URL_0_"
]
} | [] | [] | [
[
"https://en.wikipedia.org/wiki/Andromeda–Milky_Way_collision#Fate_of_the_Solar_System"
]
] |
||
3veoug | since dogs don't brush their teeth like humans, why don't their teeth decay more rapidly than human teeth? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/3veoug/eli5_since_dogs_dont_brush_their_teeth_like/ | {
"a_id": [
"cxmu66c",
"cxmuvfk"
],
"score": [
2,
4
],
"text": [
"Because they don't eat processed sugars. You can see the same thing in people from third world nations.",
"Folks have mentioned that they eat a less sugary diet. This is a true and is a factor.\n\nBut you are missing something important. A dog's lifespan is far shorted than a human. 12 years or so compared to 80-90. Yet your teeth are made of the same material. Therefore human teeth are under the effects of decay for a much longer period of time.\n\nIf a 12 year old kid who just got his adult teeth (say they came out all at the same time) ate non-sugary food and avoided acidic drinks. Then I doubt they would have any teeth issues by the time they were in their mid twenties (i.e. equivalent to a dogs lifetime). After 40 years had passed, that might be a different story. But your dog, sadly, will never reach that point.\n"
]
} | [] | [] | [
[],
[]
] |
||
1qqs7j | how do self-healing surfaces work? | How do self-healing surfaces, like dartboards and cutting mats "heal themselves?" | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1qqs7j/eli5_how_do_selfhealing_surfaces_work/ | {
"a_id": [
"cdfj0t4"
],
"score": [
5
],
"text": [
" > [Self-healing polymers follow a three-step process very similar to that of a biological response. In the event of damage, the first response is triggering or actuation, which happens almost immediately after damage is sustained. The second response is transport of materials to the effected area, which also happens very quickly. The third response is the chemical repair process. This process differs depending on the type of healing mechanism that is in place.](_URL_0_)\n\nBasically, the material has a way of knowing it has been damaged through the use of triggers such as microscopic capsules breaking from being cut. Mending epoxy then travels from these broken capsules to the cut to fill in the gap and create new bonds with the exposed surface, therefore \"healing\" it.\n\nSome other self-healing polymers are loosely woven together in such a way that when a sharp object goes to \"cut\" it, the molecules easily separate to make way for the object, and then return back to their woven state once the object is removed. None of the bonds were ever damaged, molecules were just pushed to either side. This method is more commonly used for when the object piercing it is very small, like a hypodermic needle through a thick polymer test-tube cap."
]
} | [] | [] | [
[
"http://en.wikipedia.org/wiki/Self-healing_material"
]
] |
|
3eyceq | what do flies want from me? | Why are they so insistent on landing on me for only a split second at a time? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/3eyceq/eli5_what_do_flies_want_from_me/ | {
"a_id": [
"ctjkfgy",
"ctjvmyf"
],
"score": [
5,
2
],
"text": [
"The sweat and oil on your skin has elements of sugar in it. Flies like sugar.",
"They're tasting you with their feet. This is also why they walk *all over your food* rather than just landing on one spot and staying there.\n\nIf the oil/skin-flakes upper crust of your skin tastes good, and you don't shoo them away, they'll start sipping your sweat."
]
} | [] | [] | [
[],
[]
] |
|
k1uns | moral subjectivism vs moral relativism? | Are these terms synonymous or is there a distinct difference between the two? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/k1uns/moral_subjectivism_vs_moral_relativism/ | {
"a_id": [
"c2gw4j2",
"c2gwxer",
"c2gw4j2",
"c2gwxer"
],
"score": [
6,
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6,
2
],
"text": [
"You are a moral subjectivist when you believe that there are no objective ethics, but ethical absolutes do exist (culturally for example) . In contrast you are a moral relativist when you believe there are no objective ethics and you can adjust freely your morality in different situations.\n\nBasically moral subjectivism: you know true morals do not exist, but you accept the social contract and you are not a cunt to others. Moral relativism: \"soldier of fortune\" mentality, where you can twist your morals as you see fit.",
"The relativist says, for instance, that infanticide is unacceptable when North Americans do it, but acceptable when the Inuit do it. \n\nThe subjectivist says that infanticide *is seen as* unacceptable *by* North Americans, but *is seen as* acceptable *by* the Inuit. \n\nIn other words, relativists propose that moral statements have absolute values that depend on the identity of the people performing them, whereas subjectivists propose that moral statements, being matters of opinion, have truth only to the people making them. \n\nI am a subjectivist, AMA. ",
"You are a moral subjectivist when you believe that there are no objective ethics, but ethical absolutes do exist (culturally for example) . In contrast you are a moral relativist when you believe there are no objective ethics and you can adjust freely your morality in different situations.\n\nBasically moral subjectivism: you know true morals do not exist, but you accept the social contract and you are not a cunt to others. Moral relativism: \"soldier of fortune\" mentality, where you can twist your morals as you see fit.",
"The relativist says, for instance, that infanticide is unacceptable when North Americans do it, but acceptable when the Inuit do it. \n\nThe subjectivist says that infanticide *is seen as* unacceptable *by* North Americans, but *is seen as* acceptable *by* the Inuit. \n\nIn other words, relativists propose that moral statements have absolute values that depend on the identity of the people performing them, whereas subjectivists propose that moral statements, being matters of opinion, have truth only to the people making them. \n\nI am a subjectivist, AMA. "
]
} | [] | [] | [
[],
[],
[],
[]
] |
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