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7cpeko | How does carbon dating work? | Technology | explainlikeimfive | {
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"In the high atmopshere, cosmic rays strike Nitrogen, turning it into Carbon-14 (Carbon with 6 protons and 8 neutrons). Carbon-14 is unstable and will eventually decay into Carbon-12 (6 protons and 6 neutrons). The rate of Carbon-14 generation and decay is somewhat constant, and there is a roughly static ratio of Carbon-14 and Carbon-12 in the atmosphere. Carbon-14 and Carbon-12 readily combine with oxygen to form Carbon Dioxide, which is absorbed by plants and then eaten by animals. So long as an organism is living, it will constantly be taking in Carbon that originated from the atmosphere, and ratio of Carbon-14 to Carbon-12 in the organism's body will mirror that of the atmosphere. When the organism dies, it no longer takes in new sources of Carbon. The Carbon-14 present in the organism's body will continue to decay into Carbon-12, but no new Carbon-14 will be generated. This will alter the ratio of Carbon-14 and Carbon-12 in the organism's body (until there is no Carbon-14 left). Since we know the rate at which Carbon-14 decays into Carbon-12, we can analyze the remains of an organism, determine the ratio of Carbon-14 and Carbon-12, then calculate approximately how much time would had to have passed to reach that ratio. Carbon dating is only good for dating things less than 50,000 years old."
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7cpmqn | How do the Balkans and Ottoman empire relate to the cause of WW1? | I don't understand who they are and why did they want war? Who's side were they on and what did they have to do with WW1? Besides the assassination of Franz Duke Ferdinand, I don't really know that much about them. | Other | explainlikeimfive | {
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"The Ottoman Empire was a Turkish government with control over Turkey, most of the Middle East, North Africa and the Balkan. A rising powerful empire since the 14th century, The Ottoman was in decline during the 19th. It had difficulty keeping up with the industrialisation of the western powers, the rise of nationalism in the Empire of several ethnic group created rebellions and revolt in the territory, the growing Russia became an important Rival of the Ottoman. Russia and Austria had a lot of interest in the Balkan that was controlled by the Ottoman. Surrounded by Germany, France, Italy and Russia, the Balkan was one of the few way Austria could expand their territory, since Ottoman was by far their less stable neighbour. For Russia, it was even more important because the Balkan and the Ottoman could stop naval movement from the Black Sea to the Mediterranean Sea. This was an important weakness that Russia wanted to eliminate. Additionally, most of the Balkan were orthodox, Slavs and used Cyrillic script, just like in Russia, making Russia and the Balkan culturally close. Both Austria and Russia used the rise of nationalism in the region to support revolt, which eventually lead to the independence of the Balkan (Bulgaria, Serbia, Montenegro and Greece). As the influence of the Ottoman declined in the Balkan, the rivalry between Austria and Russia for influence over the same region growth. Austria had partial control over Bosnia, while Serbia was very close to the Russian. There was a lot of Serb and other Serbo-croat (Serbian, Croatian and Bosnian are three very similar language) in territory under Austrian control, so there was a lot of tension between Serbia (backed by Russia) and Austria. When the Archduke Franz Ferdinand of Austria was killed by Serbian nationalist in 1914, Austria used that as an excuse to go to war against Serbia. This escalated into WW1."
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7cpnqh | why haven’t we built a space station on the moon yet? | Other | explainlikeimfive | {
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"Because there's little to no scientific value in doing so above and beyond what we can accomplish from the earth's orbit, e.g. the international space station. And unlike the ISS, a spare part, food, water, etc isn't a spaceflight away and if there's an emergency, you'd basically be screwed on the moon whereas on the ISS, there's return vehicles they can use to return to earth.",
"Moon has no atmosphere at all, Mars has thin layer at least. Atmosphere matters, it protects us against Sun and space radiation, it makes temperature fluctuation lesser, meteors are burnt in atmosphere as well, there is no erosion so moon dirt is \"sharp\" and harms everything. Moon has six times lesser gravity. It is dangerous and may be even lethal. Moon is too close to Earth. So if we look for another home, we can't move to the closest celestial body, because in case of planetary catastrophe it will be affected as well. We don't actually need it. We can't move resources from Moon to Earth because it's expensive. We don't need people on Moon because we can use robots for research.",
"There have been plans to go back to the moon, but the administration change and the plans change. NASA and Roscosmos are planning to build a ISS style station but in a lunar orbit. So hopefully that gets fulfilled. The lava tunnels on the moon might be a future sight, but it might be a while. China is planning to man a mission to the moon around 2025-2030 and maybe that will get the NASA's interested again."
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7cpu8a | What are the pros and cons of organic farming versus conventional farming? Which one is better? | Technology | explainlikeimfive | {
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"The main advantage of organic farming is that you can put the organic label on the stuff you sell and charge more for it. The disadvantages include smaller yields, greater chance of disease, greater use of pesticides, and greater environmental impact.",
"Conventional farming produces much higher yields at the expense of using artificial chemicals as fertilizers and insecticides. Organic farming eschews artificial chemicals at the expense of lower yields. Neither is inherently better until you make value judgements about the use/presence of chemicals, how much you trust that those chemicals are safe, what goes into producing those chemicals, etc.",
"Which is better is up for debate. Some of it comes from people's trust, or lack of trust, in companies like Monsanto. Which is an entirely different discussion. The claim is that organic farming is better for the consumer, better for the environment, and better for the worker. There's strong evidence this isn't always the case. Organic pesticides can be far worse than their counterparts. Some organic pesticides are more toxic by weight than round up and the like. People like to believe organic means healthy and safe because it's something that is a byproduct of a living organism or system. Which is not something that holds true."
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7cqfhq | How does an air fryer work? | Technology | explainlikeimfive | {
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"it's like an oven, but with the air circulating much faster and sometimes uses hotter air than what ovens are capable of. the crispness comes from fast circulation of air.",
"Many people are saying that an air fryer is just a convection oven, but try telling a pizza maker his wood-fired brick stove is \"just a convection oven\". There's many things in the design that make it better for some uses and worse for others. First up, how it works. Like a regular oven, it works by heating up air, and then using the hot air as a fluid to transfer heat to the food. It has built-in fans to circulate the hot air so that the food is cooked faster and more evenly, just like a regular convection oven. What are the upsides of having one over a regular convection oven? It's smaller and generally a better fit, portion size-wise. This means you don't have to heat up your oven just to fry something, along with the energy usage, and you can use your oven for something else as well. By that same token it's easier to clean at the end of things. It's designed to be taken apart and cleaned too. It has a built-in rack and drip tray, most have handles, and many have stirring bits built-in as well. They're *much* more convenient than sticking something in a convection oven- you don't need to worry about catching the oil drips while keeping whatever you're frying on a rack so that the air circulates evenly, & c. I've used my mom's, and it's incredibly convenient. Quick to start up, fire and forget, easy to clean. That's what you're paying for- not the technology, not the concept. Convenience. If you have access to one, try it out to see how much time you save, and make your decision yourself."
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7cqrfy | why do we eat maple syrup but not pine syrup or elm syrup or oak syrup? | Biology | explainlikeimfive | {
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"We can and do eat birch syrup, walnut syrup, and the syrups of a few other trees. The key isn't as much the sugar content, the key is that the sap needs to be relatively neutral tasting, because of how much it has to be reduced to thicken it. The saps of deciduous hardwoods (maple, birch, etc) seem to work especially well here. As far as why maple, I suspect it just tastes the most pleasant, although certainly it is to a large degree cultural as well - consider by analogy how almost any grain or fruit can be used to make alcohol, yet the large majority of world alcohol is made only using a few specific grains and fruits."
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7crd5l | I overheard my parents talking about a 504. I looked it up and it seems to be for people with learning disabilities. What exactly does it mean? | Other | explainlikeimfive | {
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"It, normally, isn't a big deal. I have ADD and it really screwed me over in high school. So once I was diagnosed I got a 504 plan. It really helped in the end. Teachers, some not all, are more sympathetic and willing to work with you on homework, tests, and the information in general.",
"It's a plan in which the school tries to work out ways to accommodate a student's special needs. > This type of plan falls under Section 504 of the Rehabilitation Act of 1973. This is the part of the federal civil rights law that prohibits discrimination against public school students with disabilities. That includes students with learning and attention issues who meet certain criteria. > Much like an IEP, a 504 plan can help students with learning and attention issues learn and participate in the general education curriculum. A 504 plan outlines how a child’s specific needs are met with accommodations, modifications and other services. These measures “remove barriers” to learning. [source]( URL_0 )",
"It’s for students with any disabilities. My daughter has a 504 since she is hard of hearing so she sits In the front of the class or gets special instructions for homework. We have to meet with all teachers at the beginning of year to go over her needs",
"I had a 504 when I was in school that stated I could not be deducted points for penmanship and could not be punished for inattentiveness because of my severe ADD. The teachers would take time to make sure the whole class understood the subject which was a good hint for me to ask any questions I may have had. I felt It was bullshit at the time but looking back I would never have made it otherwise. College didn't care about my 504 and I struggled to keep up, fortunately by then I was determined enough to do independent study and push for further review if I needed it The moral of the story is take advantage of every break you are given, they will find other ways to screw you over in the end."
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7crnfw | Why do stains become harder to get out if you leave them alone for a while? | Chemistry | explainlikeimfive | {
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"I'll try an analogy - I hope it helps. If you put down watercolor paint on paper it needs to dry (set) before the ink basically becomes \"part\" of the paper - it soaks in and dries. if the paper gets wet some of the paint will \"clean\" off. if you pour water onto the paper just a few minutes after painting on it more of the paint will wash off - it hasn't had enough time to set in, to become PART of the paper. But removing ALL the paint is very hard without chemical treatment...like recycling. A coffee spill on a white shirt becomes a stain after the coffee has had time to \"set\" - basically the stain binds to the shirt and becomes part of it. If you act quickly you can remove the coffee (paint) before it gets a chance to bind to the shirt (paper) and become a permanent part of it. Some \"paints\" are harder to remove than others."
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7crvc7 | why can’t aluminum foil burn under just an open flame? | More specifically why can’t it catch fire is what I mean. | Physics | explainlikeimfive | {
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"Aluminum is not flammable. When it reacts with oxygen (like a rusting or burning sort of thing), the aluminum oxide quickly forms a protective coating just a few molecules thick, protecting the rest of the aluminum."
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7cs7ct | What exactly is happening in our brains when we constantly check the fridge for food with full knowledge that no new food is there? | Biology | explainlikeimfive | {
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"Why do we check our timepiece (watch/phone) for the time when we've just done it a few minutes ago? Many things go into short term memory all the time - but it is exactly that - short term memory. Here today (now), gone tomorrow (or just a little later). If you looked into the fridge and did an inventory and wrote it down, you'd be much less likely to check it again and again - you'd have put the effort in to put the information into long(er) term memory. Also: we often look in the fridge not knowing what we want. Still hungry we check it again hoping something will \"click\" (yeah, leftover pizza, why not). But until something \"clicks\" the driving force (wanting something to eat) isn't fulfilled - so we check again...and again. - it's not LOGICAL - it's an emotional / physiological motivation driving us. Not a lack of data/information.",
"I've thought about this a lot because I did this a lot. My thought process went mostly like this: Checks fridge for food, sees nothing notably interesting or anything that sticks out. Checks cabinets and pantry for food, same result. Tells self that the fridge can't possibly have *nothing* and check again confirming that there's nothing worth eating. Does same thing with cabinets and pantry. Tells myself to just look in the fridge and stop being picky. Close fridge and decide to take my chances with some chips from the pantry. Convince myself that chips aren't going to cut it and go back to the fridge and eat some yogurt."
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7csal3 | the making of the Slash (the border between Canada and the U.S.) | Other | explainlikeimfive | {
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"This video by grey goes over the creation as well as other things concerning the us Canada border URL_0",
"It is a national border which means it must be watched, and clearly marked. The way that the US and Canada have chosen to do this in many of the heavily forested areas of their border is to clear the forest over that area.",
"Borders between friendly neighbors don't matter much. (See [Schengen Area]( URL_0 ).) Borders between hostile countries do. (See: millions of Canadians swarming over the border with hunting knives, for reasons I can't even imagine but I am certain there is someone in a northern US state who is preparing to repel them *just in case*.) Historically, countries have not always been able to tell when their neighbors (or they themselves) were about to turn hostile, so keeping the borders clearly marked and clearly visible became a prudent practice. The Canada/US border being heavily infested with trees, protected by (on the one hand) Mounties riding moose (meese?) like Thranduil come to Erebor, and (on the other) by helicopters straight out of Apocalypse Now, neither country able to effectively police their side of the line, prompted the two countries to create a ~~killing zone~~ ~~DMZ~~ open space on either side of the line. There are many precedents for this: the DMZ between North Korea and South Korea, the minefields and large wall separating the two sides of Berlin, the double row of fences around prisons. All designed so everyone knows exactly where the imaginary line is, and exactly what will happen to anyone who tries to cross it without permission from the relevant sovereign power. tl,dr: To prevent Entmoots."
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7csdpi | How do Apps track your sleeping? | Technology | explainlikeimfive | {
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"text": [
"If it's an app, mostly motion detection, with perhaps some sound detection! If it's a smartwatch, most likely pulse (it changes with your sleep and the stages within it) and motion detection!"
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7csol7 | how do we capture helium and put it into tanks? | This probably seems like a very basic question but how was it discovered and how is it harnessed for everyday use? Wouldn't it just float away? [other] | Technology | explainlikeimfive | {
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"Helium is extracted from natural gas, kind of like how gasoline is extracted from petroleum (oil). It won't float away because it is PART of the natural gas. Since it is extracted in a controlled environment it can be separated from other products, like butane (think cigarette lighters) and propane (think gas BBQ grills). Each product is removed at a particular fracking stage and stored into separate tanks. this is an oversimplified explanation...but this is ELI5. You can google fractional distillation or wiki it for the science(y) details of how the process works."
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7csrxw | Why does each major City on the US/Mexico Border have a similarly-sized City opposite the border from it? | Other | explainlikeimfive | {
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"Quite a few of those border cities predate the territory's annexation into the US and were founded back when it was all Spanish territory. You also need to remember that, prior to the modern era, (back in the \"Wild West\") border enforcement wasn't all that strict. Cities, especially in the desert, are generally built where there's a good source of water. if you use the river as the line for the border, it's natural for people to want to live on both sides of it.",
"Trade/money. People live where they can obtain necessities and gain employment. People on both sides benefit from business conducted on both sides, plain and simple, from companies to (mostly day) tourists."
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7cswnn | Do fish in aquariums know they’re in aquariums? Can they tell the difference? | Does it vary among different types of fish? | Biology | explainlikeimfive | {
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"Believe it or not, [fish can get depressed]( URL_1 )! Anecdotally, as someone who works in the aquarium industry I've heard countless stories of fish that acted differently when moved to a different tank: for instance, when moved to a smaller tank they sat on the bottom, were less active, displayed stress coloration more, and refused to eat. On the other hand, fish that were moved to a larger tank became much more active. (And not just inappropriately small tanks, but also tanks that were big enough, if a little cramped.) Fish also display differences in behavior when decorations are added or removed, when other fish in the tank die, etc. /u/equus007 is partially mistaken, in that while *most* fish you find in aquariums were probably captive raised, if not captive bred (the difference being that captive raised fish may have been harvested as eggs or very young fry, but not actually bred from captive parents) and lived their whole lives in aquariums, not all fish are. In fact, the vast majority of saltwater fish are wild caught. Only some species of clownfish, seahorses, *very recently* some tangs (including [blue regal tangs]( URL_0 )), and one or two other species are bred in captivity. All other saltwater fish are wild caught, so they're definitely not used to captivity. And sometimes it shows. Some fish take well to captivity and adapt, easily switching their diet to include prepared foods like pellets and flakes and/or frozen foods. Some do not, and never accept prepared foods. Some never accept food in captivity at all! They get stressed out and can't calm down enough to eat. I don't think a fish has the capacity to understand the concept of *captivity*. I don't think they understand that they are in an *aquarium* in any sense other than the understanding that they're in a very different environment than what they're used to. Even captive bred fish have instincts that evolved for living in the wild that have to be either adapted for captivity or accommodated by someone keeping them. But they do absolutely understand the limitations of the environment around them. They understand the size and shape of the tank surrounding them. And they understand that this new surrounding is not *normal* until they get used to it and it becomes their new normal. EDIT: Also worth noting, it *totally* varies by fish. Some fish are very intelligent. Remember, \"fish\" is a broad category, almost like saying, \"Are mammals intelligent?\" Well, *some* of us are, eh? And you're more closely related to, say, a bony fish like Dory than that bony fish is to a shark, even though they're both called \"fish\". The family [mormyridae]( URL_2 ) is quite intelligent - they have one of the largest brain mass to body mass ratios of any animal! Again, anecdotally, most saltwater fish seem to be pretty intelligent - as far fish go - especially puffers, triggers, and eels. If you're willing to expand your explanation to include other undersea creatures, like cephalopods, they're absolutely intelligent enough to understand what an aquarium is (even if they probably still can't understand the abstract concept that is \"captivity\"). Octopuses have been known to crawl out of their aquariums and into nearby aquariums to snag some fish, and then back again to avoid getting caught doing it."
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7ct8ar | If a product says 0g of sugar per serving, how much sugar can potentially be in the product per serving? | I'm lactose-intolerant, so I shop for cheeses and other dairy products that have 0g of sugar, because lactose is a sugar. Recently, I found some mozzarella at the grocery store with 0g of sugar. Is it safe for me to eat it? | Chemistry | explainlikeimfive | {
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"I'm not an expert, but I did a google and here's a [relevant post]( URL_0 ) for you."
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7ct9mb | Why do most hallucinations instigate fear to the person suffering from it? | For example (sorry if the example is poor, but hopefully someone can get my point): most Schizophrenics see things that look threatening or hear voices that tell them to hurt themselves or just say horrible things that scare them. | Other | explainlikeimfive | {
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"Believe it or not it's actually influenced by the culture you are in. The eastern world, Asia, India etc...voices and hallucinations are nice and kind and encouraging for the most part, here in America they are harsh and mean. It's an environmental thing."
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7ct9n0 | why does UV light make sperm & salvia glow ? | Biology | explainlikeimfive | {
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"When the UV light hits molecules, it can give them energy, 'exciting' them. Compounds glowing is caused by their electrons getting excited, going up an energy level, and then releasing a photon of a certain wavelength when they fall back down. What wavelength (and therefore what color) the light is depends on the molecule. Some of the chemicals present in bodily fluids just happen to release visible light when they do this, which is why they seem to glow while other materials don't under UV light."
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7ctbug | Why there is so huge difference in wages between different countries? | I'm talking mainly about the minimum salary between various countries in the world, what causes the huge difference between countries even though geographically they may located just an hour drive from each other and have similar 'natural resources'? | Economics | explainlikeimfive | {
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"There's all sorts of reasons, here's some of the major ones, mostly having to do either with how business works or how one dollar introduced to an economy multiplies in value as it gets spent on other things within that country. Manufactured goods. You might have near-exact resources as someone else but if you turn your coal into carbon nanotubes for a space elevator while your neighbor burns it for heat, you're going to get a lot more value out of yours and therefore be able to pay for higher-paying jobs. Tax rules and corruption. If it's very expensive to do business in country A due to having to pay taxes and keep the local officials happy, big businesses will set up instead in country B... Warfare and political stability. ...especially if country B is not driven by a crazy tinpot dictator who likes to foam at the mouth while shouting imprecations at the Great Satan. Education and demographics. A trained relatively young population is attractive to businesses that work in high-margin industries where a lot of money gets paid. Countries that train their kids in information technology are going to be richer than countries that offer no such support. Tourism. Service industry jobs are everywhere, but high paying service industry jobs aren't, and they have a tendency to cluster in areas where it's safe and where there are bucket-list attractions that people will pay extra for. This can really drive a local tourism industry and employ a lot of people. Geography. It's easier to sell stuff when you can quickly and efficiently reach your target markets. Since water's pretty much the cheapest way to ship anything, coastal countries have an advantage here. Negotiated trade agreements. You and your neighbor might sell the same stuff, but if you've negotiated an agreement to sell all of your stuff easily while your neighbour struggles, you're going to have a more reliable market. ...and lots more."
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7ctit3 | What do grocery stores do with all their expired food? | Economics | explainlikeimfive | {
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"Many throw it away for legal reasons, others donate to charity (yay tax writeoff!) and others will do manager's special to clear the shelf at a discounted price. I worked at a large grocery chain, and at the end of each night our job was to ensure proper rotation and that \"codes\" (food that have a use or sell by date of the next day) were pulled, scanned, and placed in designated donation carts for pick up the next morning.",
"Stuff that is actually expired and has gone bad gets thrown out. Most product that is coming off the shelf is still safe to eat, just not the best, so a few different things might happen. Some stores will mark it down or put it on a special sale. Other places donate their past its prime but still edible product to food banks. I worked in the bakery and deli departments. Both of those departments also had ways of reusing product. In the bakery, we would cut up all the bread that came off the shelf and make croutons and crostini. In the deli, we used the rotisserie chickens that we didn't sell to make chicken salad."
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7ctjtt | How can it be that in Lasers, the photon(s) that lead to the stimulated emission within the resonator are unaffected in their energy? | As I learned, two photons with the same wavelength and thus energy will be emitted in Laser devices. So, there is some sort of interaction between the photon and excited electron. In fluorescence this results in energy loss and is defined with the Stokes shift. Is there something similar for stimulated emission in Lasers? Edit: AskMeLikeIm5: is there something like a Stokes shift in lasers that affects photon energy? | Physics | explainlikeimfive | {
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"In fluorescents, the photon is the what is energizing the atom. The photon is absorbed and the electron goes into a high energy state matching the energy of the absored photon. Next, the electron transfer into lower but still high energy state. Through these small transition, a phonon takes the energy away. That is, a vibration. Phonon to phone as photon is to photo. It may do this more than once to, depends on the material. Finally, it ends up in a longer lasting high energy state. It will sit in this state for a while, before spontaneously dropping back to the original ground state. This drop releases the energy as a photon, but since the electron already dropped some steps down and gave away energy to phonons, the resulting light is of a greater wavelength. Now with a laser, stimulated emission occurs. First we pump the medium. That is we add energy to it, typically done with electricity. This does the exact same thing as the incident photon did in fluorescence. The electron might then jump down a few small steps interacting with phonons, just like fluorescence. And again, it ends up in a final state where it's waiting to spontaneously emit a photon. However, rather than randomly occuring, another photon that has already been released by another atom passes by. This triggers the emission to happen right then, rather than spontaneously later. The emission is stimulated. The incident photon isn't donating it's energy to energize the electron, the pumping process already energized it and contributed the excess energy lost to the initial drops of energy to phonons that fluorescence sees. There's no stoke shift because the electron is already sitting in the state ready to with correct amount of energy. Now what seperates a fluorescent material and a lasing material is simply the amount of spontaneous versus stimulated emissions. Even in a fluorescent, there is stimulated emissions occuring. They just are vastly outnumbered by the spontaneous ones. There's not enough energized electrons sitting around, be that from the temperature or the higher frequency incident light. However, with a laser we are injecting lots of energy into the medium and something called population inversion happens. What that means is that we add enough energy that more of the electrons are actually energized and waiting to emmit rather than sitting in the ground state. Once you've done this, stimulated emission will be dominant and you can get a amplification of the light. Light amplification by stimulated emission of radiation, LASER. If you had an ideal substance with a direct bandgap and only a true single higher energy state, then there wouldn't actually be any difference other than in coherence. There'd be no exchanging of energy (or momentum) to a phonon. So with fluorescence, there would be no stokes shift. [Here's]( URL_0 ) a diagram actually showing the states I'm talking about. Note the two higher energy states. Also, of note this diagram is actually showing it being optically pumped. That is, higher energy photons are what is energizing the medium. If you actually ignore the stimulating photon and pretend that second emitted photon is just randomly released on its own at some point, that's fluorescence with the stokes shift."
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7ctnhc | Why are wounded soldiers always thirsty? | I was reading Alexander the Great's biography and the author mentions that wounded soldiers always cry out desperately for water. I have come accross this in other books about historical battles. Why do wounded soldiers always beg for water? | Biology | explainlikeimfive | {
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"Water is your second most basic biological need, after air. If you are wounded and left for dead on the battlefield, you're obviously not capable of going to get your own water. It's not going to take you more than a few hours to become thirsty even if you aren't bleeding severely. If you are bleeding, loss of blood volume is going to be sensed by your kidneys, which will increase the urge to drink water.",
"People often underestimate how long soldiers are in battle. Historically, many go for *days* (sometimes more than a week), during which they have no time (or authority) to put down their weapons and go get food/water/rest. You do that after the battle is won. Given that, it's no surprise many battles and even entire wars have been lost due to being ill-prepared for the basics (Nazis invading Soviet Russia, for example, were overwhelmed by the climate). Even today as wars become less about manpower than they are wars of tech, soldiers can still sometimes go for up to 48 hours straight without any basic needs (Benghazi comes to mind). The first thing they do after a gauntlet like that is water, sleep, food (usually in that order). Couple that with the fact many conflicts take place in very arid climates, and you have some very thirsty boiis. Source: (former) civilian contractor, have worked overseas with the marines and army"
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7ctpqy | How can someone (Bill Gates) go and just build a city? How would he get the permission to do that? | Other | explainlikeimfive | {
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"Well....if he has enough money to buy the land....he can build whatever he wants. Now whether or not he can get anyone to come there??? Depends. But then if he creates an awesome city and invites people.....I think they will come",
"If they buy the land they can basically build whatever they want on it. This includes building a city. Because there is no city government to talk with (yet) there is no need to get building permits for most things, and the State and County permits they do have to get are few and generally easy to get if you are building on private property (as they would be doing). So physically building it is easy. The hard part would be prompting people to move there and populate the city."
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7ctsgq | When bacteria die, for example when boiling water, where do their corpses go? | Biology | explainlikeimfive | {
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"When you take a close look at a bacteria, it's just a little bag of chemicals with a protective skin around it, plus some other stuff like hairs that can help it move. The chemicals are mostly water plus electrolytes and a few complex carbon-based molecules. If the bacteria is placed in boiling water, the pressure inside rises and ruptures that skin, and then the chemicals inside leach out and dissipate into the water, while some get changed into other chemicals in the same way stuff like an egg changes when it cooks. But it's such a tiny amount of material and it's dispersed so thoroughly through so much more water that it's not noticeable or harmful or anything. Baking or frying it does the same thing, rupturing the skin, except in this case there's no water to carry the chemicals away, so after the fluid in the bacteria evaporates you have a itsy-bitsy stain. RIP bacteria.",
"If you boil water to kill bacteria, the dead bacteria remain in the water. If you steam distill water to purify it, the bacterial corpses will be left behind when the water evaporates. Filters can also remove viruses and dead bacteria from water. Bacteria can leave behind harmful toxins after they are killed, which may resist boiling. Depyrogenation is the process of removing or neutralizing these toxins from a solution.",
"Essentially they turn into weak soup. It's like boiling any vegetable or meat, only smaller. Much smaller.",
"To answer your question: it stays there. That's why there are certain medical equipments that need to have the dead bacteria bodies taken off before they can be used and to speed up healing. Anything that isn't made readily gaseous is going to stay - especially if you use methods of cleaning like auto-clave.",
"They burst apart or are eaten by macrophages, or both. They leave a bunch of debris behind, which is eaten by some other microorganism eventually. or it biodegrades utterly.",
"As others have mentioned, heat in the form of boiling water essentially dissolves the bacteria into more basic elements. Heat in the form of air (baking or frying) does the same, only it vaporizes it. But interestingly, soap works in a similar way. Soap chemically dissolves the protective \"skin\" of bacteria, effectively doing the same thing heat would to rupture it, only chemically."
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7cu3g8 | how, in cases such as schizophrenia, does the brain create such realistic audible and visual hallucinations while the person is conscious? | Biology | explainlikeimfive | {
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"When we hear or see things, it's really just our brain interpreting the electrical activity of neurons caused by vibrations (sound) or radiation (light). Our brains are really good at creating its own electrical activity to transmit data between parts of the brain (this is what seizures are), so it makes sense that some people would experience hallucinations while under the effects of certain drugs or mental illnesses (like schizophrenia, in which certain parts of the brain may not be communicating correctly between each other). Hell, \"thinking\" is halfway there to a full hallucination. We can conjure images, sounds, even videos in our mind without any effort at all. It's just that in the brain of a schizophrenic, those subconscious efforts are difficult or impossible to distinguish from reality.",
"I'd like to build off of what /u/Kotama said: > Hell, \"thinking\" is halfway there to a full hallucination. We can conjure images, sounds, even videos in our mind without any effort at all. I want you to imagine a purple elephant in a pink tutu, holding a battle axe. He is fighting Darth Vader on a grassy battlefield. There is no way in hell that you or I or anyone has ever seen that. You came up with it in your mind, because the brain is very good at taking things we HAVE seen (elephants, the concept of purple, Darth Vader) and combining them together. That is literally the definition of a hallucination. You just hallucinated about an elephant-sith battle. The difference is that with schizophrenia, you can't tell that it's fake.",
"I can answer for auditory hallucinations. Our hearing is mostly processed in the temporal lobe. It has been observed that, when a schizophrenic is experiencing an auditory hallucination, the temporal lobe is more active than when it is not hallucinating, while another part of the brain, within the temporoparietal lobe, is busy generating the forethought to speech: sounds, words, etc. These regions of the brain are not communicating: the part generating speech isn't letting the temporal lobe know that this speaker is hearing their own voice, therefore their brain processes this stimulus as a 'genuine' auditory experience. If our brain doesn't know for sure that we're speaking when we hear a voice, we automatically assume that the voices are talking TO us."
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7cu8bk | Why do grey hairs appear to be very thick and strong, aren't they dying? | Biology | explainlikeimfive | {
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"No they are not dying. Grey hairs have simply changed pigment and are just as alive as any other hair on your head.",
"I don't know why they sometimes appear thicker, but they are not dying. I mean, no hair is alive but the cells that produce them may still be going strong even if the pigment production is turned off.",
"This is not a thing scientists agree on. Some say it's because the cells that produce the hair strain are damaged therefore the pore that it comes out from is misshaped. Others say that together with greying, the cells don't produce as much oil as they should, making the strain coarser and more breakable. And some recent researchers are noticing that the grey and white hair strains have Hydrogen Peroxide (H2O2), which is a byproduct of metabolism byproduct, making the hair bleach itself. The research on that is recent and focused on other effects of H2O2 on you. In fact that might also be the reason people have vitiligo."
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7cv2an | Why do sites like PirateBay and WatchSeries constantly change domains? | Technology | explainlikeimfive | {
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"They are being actively hunted by various anti-piracy organisation s. To counteract getting the domain banned/vlocked by providers, they change it, thus being able to continue operations."
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7cvcrs | What is a Deodorant/antiperspirant and how do they work | I still have a lot of questions about them including these Are they safe to use ? What are the difference between them ? Is it ok to use both of them at the same time ? Should I apply deodorant if my armpit smells bad ? and Are tawas or alum safe to use as a deodorant ? | Biology | explainlikeimfive | {
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"Antitranspirants lower the amount of sweat that leaves your body. Usually by clogging up the pores (afaik that is what the aluminium salts are for) or making the pores close up by themselves and forcing your body to get rid of the sweat another way (which it surprisingly can). A deodorant only prevents the build up of bacteria (your sweat does not smell but the bacteria that feed on it and break it down produce the smell). Some really bad ones just mask the smell. That is why perfume is no substitute for deodorant but a different thing that should never be put under your arms. They are safe to use but some sources claim aluminium salts are unsafe because aluminium builds up in our body and causes major harm. If you suffer from excessive sweating you might want to see a doctor. Last I heard BOTOX into the armpits deactivates the sweat glands there. Otherwise I recommend using deodorants. It lets your body sweat to control the temperature and it kills the smell. I recently bought an all natural deodorant and it surprisingly is the best one I had to date. Insanely expensive though and smells of white chocolate since cocoa butter is the main ingredient. Antiperspirants usually feature deodorant like qualities as well. If your problem is smell but you do not have a problem with the moisture you need to find a deodorant that works for you and very importantly a soap or shower gel that cleanses you well because getting rid of old bacteria is half the effort of preventing smell. After a day almost everyone develops a mild smell, even with deodorant. Regular showers are imperative to fight body odour if you have any. Alum works to some extent because it is an astringent that pulls the pores closed. It is not particularly strong though and only works for some people. For me it did not.",
"Antiperspirants control the sweating and remove the smell that way. Deodorant simply covers up the smell and some deodorants kill the bacteria that create the smell as well (the sweat itself isn't what stinks). Most of what's available in the store is a combination so you shouldn't have to worry about it. However, if you do have to choose between the two, then you'll probably prefer how an antiperspirant keeps you dry."
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7cvpcr | If you didn’t swallow your own saliva would your mouth just fill completely with saliva or would you just stop salivating? | Biology | explainlikeimfive | {
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"Saliva is produced by the stimulation of salivary glands by parasympathetic nerves when we put food in our mouth. If you don't swallow your saliva, the body with continously think that you're eating and won't stop producing saliva."
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7cvrmx | why do some medicines hurt your stomach if not taken with food? | Biology | explainlikeimfive | {
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"While the reason why varies from medicine to medicine, the most common reason is the medicine being acidic and affecting your stomach acid's pH level. When the medicine is diluted by water or especially food, the symptoms disappear because they bring your stomach's pH level to a more normal ...level."
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7cvzdc | Meteor strikes on the moon. | Why is it that the Moon is clearly covered in meteor and asteroid strikes and yet the Earth has only a few over the years. I get that many strikes would get burned up in the atmosphere, but the Moon is *covered* in craters. | Other | explainlikeimfive | {
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"Craters on the Earth just get eroded away from wind, water, life, etc but on the moon they are permanent, only getting covered up by dust from other impacts.",
"There are multiple reasons. One is the Moon has no atmosphere for anything to burn up in. No atmosphere also means no weather to erode the surface via wind and rain. Anything that happens on the Moon will stay that way unless an external force changes it. This means a crater on the moon that happened millions of years ago will still be around like it just happened (unless another meteor hits in the same spot). Second is that the Moon is not geologically active like the Earth is. Land on Earth floats on a molten area around the core causing the surface to change over time (this is why we have mountains and cliffs and such). Impact sites on Earth can effectively be erased because of this.",
"> I get that many strikes would get burned up in the atmosphere, but the Moon is covered in craters. You just answered your own question. It doesn't take a large meteor to leave a large crater. Many of the meteors that left those craters on the moon would have been small enough to burn up in Earth's atmosphere. Space is a turbulent place, especially when the gravity from the sun and its surrounding planets gets involved. Meteors come our way frequently, but most of them simply burn up and that's that. No one pays them any mind (well, some people do) because they aren't large enough to remain intact after hitting our atmosphere. Since the moon doesn't have the luxury of an atmosphere, each and every meteor makes it to the surface no matter how big, and as a result, it's covered in craters. Also, it's worth pointing out that the craters on the moon are the result of billions of years of bombardment. After a while, that begins to add up."
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7cw4e9 | Why do people get addicted to drugs but not to stuff like work and studying? | Biology | explainlikeimfive | {
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"your question is wrong. They do. Usually it's sports or work, studying less so, because it is less immediately gratifying. people get addicted to all kinds of stuff.",
"Funnily enough, there are people who get addicted to work and studying. Addiction (at it's most basic level) has something to do with dopamin release in your brain, as in, when something you do or take makes you feel good, you subliminally want to do/take it again and your response to being able to do/take that thing or not changes over time, making you depended on it. Edit: The reason most people don't get addicted to work or studying doesn't make them addicted because it doesn't make them feel good. Being paid or rewarded however is immensely addicting and causes people to feel obligated to work and study beyond what would be deemed rational.",
"They do. Anything that causes a pleasurable sensation can cause a pathological addiction. Psychiatrists regularly recommend to people that they work or study less and find more time for leisure or sleep. A big difference though is that unlike many drugs, people do not get a chemical dependency on working. People can be fully committed to quitting heroin, but they'll still suffer from the agonizing symptoms of withdrawal and experience cravings. Chemical dependency makes it easier to get addicted and more difficult to stop.",
"May drugs, including the notoriously addictive stimulants (methamphetamine), opiates, and sedatives (benzos), have a direct effect on the brains chemistry, often generating a euphoric feeling with no effort. They also often have a negative withdrawal effect, encouraging continued/habitual usage.",
"People can get addicted to anything. Drugs that have a physical addictive properties just have a very powerful tool in getting people addicted. They work by producing chemicals in the brain that presumably make you feel good. and that is the addiction. But if lets say a very studious person feels a great sense of accomplishment after studying and that causes a rush of chemicals in the brain that makes them feel good. It can be very addictive. However we never identify these people because it is counted as a good thing, so you don't notice it. Unless they get little highs by correcting you each time your wrong. Just don't hit the twerp, he's addicted to being smugly correct all the time."
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7cw74l | That cool throat sensation that occurs when drinking something after you just chewed mint gum or eaten a peppermint. | Biology | explainlikeimfive | {
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"Chemical compounds come in every sort of variety you can imagine. The cool sensation from \"real\" or \"artifical\" peppermint flavor is the result of a unique shape and configuration of a molecule who can bind to receptors in our mouth and throat. This (like capsaicin in hot peppers) produce changes in these receptors, which tell our brain \"oo, cold\" when in actuality its not. When you eat or chew something with these peppermint molecules, the amount of peppermint flavouring in your mouth increases by a huge amount. When you drink, a good portion of this huge amount then slides down your throat, and is also pushes up the back of your throat, out of your nostrils, in vapor form. Your mouth, throat, and nostrils (and other areas), can detect this conformational change caused by the peppermint molecule, and next thing you know, you have a cool sensation."
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7cwcho | What is the point of those wooden honey-dipper things? | Why wouldn't you just use a spoon? | Other | explainlikeimfive | {
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"A former boss at a fancy restaurant I worked at once told me that the point is to be able to drizzle honey on things consistently and evenly, where as other tools like spoons would leave big drops here, little drops there. Makes the presentation better, I guess.",
"There's nothing wrong with using a spoon, but the slotted ball on a stick honey dipper allows you to rotate it and break the trickle of honey that gets everywhere. It makes less of a mess."
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7cwk6u | How do chlorofluorocarbons create holes in the atmosphere? | Chemistry | explainlikeimfive | {
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"When UV hits a CFC molecule, the chlorine atom is separated from the molecule. This atom interacts with ozone (O3) molecules and strips off an oxygen atom to form ClO + O2. Free oxygen atom interacts with ClO to form a more stable O2 + Cl. The chlorine atom continues this process of splitting ozone molecules several more times.",
"They don't \"create holes\", and possibly you are referring to the \"ozone layer\" instead of the \"atmosphere\". To ELI5, CFCs are chemical compounds that react with ozone and in that reaction the ozone gets consumed to form other chemicals. But we need the ozone to protect us from some radiations from the sun, so the problem is the thinning of the ozone layer. I think I recall hearing this depletion of the ozone layer is worse in some regions (probably due to the climate and winds, etc) so it became a common term the \"ozone hole\" for those areas."
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7cwlsj | How are companies able to lower the costs of items on Black Friday? | Economics | explainlikeimfive | {
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"A couple factors: - Loss leaders: get you into the store for the $200 4K TV, and then sell you lots of other stuff with enough margin to make up for selling the TV at cost or even a small loss. Maybe they lose $10 on the TV and make $100 on the toys and clothes you also buy. - Closeout Product: TV makers dump the remaining old versions of their TVs, or the ones that didn't sell because they were poorly rated, etc. and they just want to get rid of them and sell to retailers for cheap. (to show possible mark downs, I used to work for a closeout retailer and I remember our merchandiser getting old versions of Rio MP3 players that had recently been selling for $99 for just 30 cents each when the newer, higher capacity versions became the norm. So even if we got $30 for them we made more margin than Best Buy had when selling for full price) - Specific low spec models for Black Friday: some makers produce lower spec, lower feature models for Black Friday because people see 50\" for $200, but don't dig into all the bells and whistles, etc.",
"A few strategies may be employed. Many items may be sold close to the retailer's own cost, and a few items may be sold below cost. The retailer hopes to make up money on volume, and other purchases made at the same time. (If the store did no Black Friday sales, it would mean a lot of lost revenue/profit). Manufacturers sometimes make specific models, often with less features or a lower quality, specifically for these kinds of sales promotions, so that the lower price point is reasonable.",
"There are a few strategies that are used. The largest one for electronics is to release a bad batch of product under a different brand name. Companies regularly do quality control tests on a batch of a product, and if the selected ones fail, the batch is deemed below quality, and they expect a lot of exchanges on it. However, rather than just throw out the batch, they will sell them at a reduced price to stores for these kind of sales. Slap a different brand name on it and you don't risk damage to your brand. Another strategy is something called a Loss Leader. You may put something that is somewhat inexpensive on sale (Such as a new video game) in hopes that it boosts related product sales (like extra controllers). This is actually a tactic used year round, but can be pushed a little harder than usual with these big sales. They may also be moving product that is about to be replaced. If a new edition of a product is available, you may want to sell off the older ones at a smaller profit to ensure that you're not sitting on stock. Think about how often you hear ads for car dealerships with all their previous year models with prices slashed and 0% financing. One other thing that happens in Canada/UK/Aus/NZ is Boxing Day sales. Right after Christmas, a similar sale happens. This has two things to accomplish. The first is to reduce extra stock that was taken on during the Christmas rush. Stores often bring in so much extra stock that they put up extra shelving, and that has to be removed, so the stock has to go somewhere. The second is that a large amount of gift cards are sold for Christmas, and that is a lot of revenue that the store cannot recognise until they are used. This creates an incentive for people to use them right away on a purchase they may have sat on until after the stores fiscal year.",
"They may have a profit margin big enough that they can lower the cost for a sale and still make a profit. They may do \"doorbusters\" where they actually lose money on the product, but very few people wait in line just to buy one thing and usually end up buying other shit that is more profitable."
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7cwmcf | How do anti-anxiety medications work? | Biology | explainlikeimfive | {
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"Depends on the anti-anxiety medication. * Benzos (stuff like Valium or Xanax) work by increasing the amount of a certain naturally-occurring chemical in your body (GABA). GABA, among other things, slows down how quickly your nerves fire... including the nerves that alert your brain to be anxious. * Anti-depressants work in a bunch of different ways depending on the kind of anti-depressant. SSRIs are different from NDRIs are different from MAOIs. But basically, they work by making it so that certain chemicals in your brain (like serotonin or dopamine) don't get absorbed as quickly, so they can float around in your brain for longer. That lets you collect more of those chemicals, which means that you feel the effects of them (usually happiness or energy) for longer than you normally would."
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7cx5jv | Why animals don't do warm-up before hunting? | Won't they get injured? | Biology | explainlikeimfive | {
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"They do. Cats and canines do some pretty obvious stretching upon waking. Then they walk, typically, to a site for hunting. Edit: there is also growing doubt about the real benefits of stretching immediately before heavy exercise."
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7cxppu | The Light Cone. | Here's a link to the wikipedia page: URL_0 I'm having trouble actually grasping the concept. | Physics | explainlikeimfive | {
"a_id": [
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"text": [
"It may be easier to look at [this diagram]( URL_0 ). In this diagram, all the spatial dimensions -- length, width and height -- have been collapsed into one dimension: this is the horizontal line marked \"distance\". The vertical line represents the fourth dimension: time. We are all moving forward in time: on this diagram, the \"distance\" line would be moving upwards at a constant rate. The point where the lines intersect represent *here* and *now*. The diagonal dotted lines represent the speed of light, the speed limit of the universe. So you're at the mid-point, the intersection of the horizontal and vertical axes, and you switch on a flashlight. In the real world, the light extends outwards in all directions (until something blocks it) at the speed of light. On this diagram \"all directions\" are represented by the \"distance\" line: as time moves on (represented by going up), the light spreads out (represented by extending to the left and to the right). Put another way: as you move up the diagram, the line representing how far the light has gone gets wider. The result is the triangular area marked on the diagram as \"future light cone\". As already mentioned, the speed of light is the fastest speed there is. So the \"future light cone\" also represents all the points in spacetime that you could theoretically get to. Take, for example, the moon. It's about 400,000 km from the earth. How does this show up on the diagram? You might think it's a dot on the \"distance\" line 400,000 km away from you, but don't forget that we have time on this diagram as well, and (barring a cataclysm astronomers have somehow not managed to predict) we fully expect the moon to continue existing for a very long time. So it shows up as a vertical line, parallel to the \"time\" line, and 400,000 km away. Part of the moon line is outside the future light cone: you will never be able to get to any part of the moon line outside the light cone, because that would mean travelling faster than light, which is impossible. About 1.3 seconds up, though, the moon line crosses into the light cone, and this part of the line you could theoretically reach. So: the future light cone shows you all the points in spacetime that you could in theory travel to, if you had the means. The past light cone shows all the points in spacetime from where somebody else could theoretically reach you."
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7cxrfh | Why do objects that are wet look shiny? | Other | explainlikeimfive | {
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"dptfodv"
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"text": [
"Water fills in all the tiny dents and cracks in a hard, rough surface and creates a smoother, more reflective surface. Both surfaces reflect, but the uneven dry surface just bounces light around randomly instead of creating a clear reflection."
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7cxs23 | Why are some large batteries (like Tesla's) made up of smaller cells? | Laptop batteries, electric car batteries, bike batteries, etc. all seem to be made up with a bunch of 18650 standard cells. Why? It seems inefficient given that the shell of the battery takes up space, and since it's cylindrical, means you have wasted space within the battery pack. | Technology | explainlikeimfive | {
"a_id": [
"dptn97v"
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"text": [
"Because electrically, one huge single cell battery would be extremely inefficient. Spreading the load over multiple cells is how we make batteries work for more cycles, especially longer cycles that electric cars need. If we used a giant single cell battery in something like a car, it would run very hot, be enormously heavy, probably have a range of 10 miles, and the battery would probably need to be replaced after 100 cycles. Electric vehicles demand a specific, high voltage, with the longest deep cycle possible. Multiple small batteries is the safest and most efficient way we can do that with the technology we have. 18650s currently are the cheapest and most reliable way we can do that on a mass scale. tl;dr it's much more efficient to run multiple cells in series than less batteries in parallel (or one single cell)."
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7cxwl7 | Sibling DNA | I think I understand parents' DNA: no matter what, we get 50% from each parent. And I think on average, full siblings have on average 50% in common too, right? But since we're getting any 50% from each parent, wouldn't it be possible for each sibling to have anywhere from 0% to 100% in common (at least in theory)? We could have exactly the same 50% from our mom, for example, or exactly the opposite 50%, right? So anyone in our direct line (mothers, fathers, grandparents) would always have a set amount, but anyone branching to the sides (siblings, uncles, aunts, cousins) would have a variable amount of DNA in common with us, right? | Biology | explainlikeimfive | {
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"> But since we're getting any 50% from each parent, wouldn't it be possible for each sibling to have anywhere from 0% to 100% in common (at least in theory)? We could have exactly the same 50% from our mom, for example, or exactly the opposite 50%, right? This is possible, yes. Unlikely, but possible. > So anyone in our direct line (mothers, fathers, grandparents) would always have a set amount... Actually, no. Other than your immediate ancestors (aka: parents) there is no specific known percentage of genes you have that originated from a grandparent or great grandparent, as you could theoretically recieve every gene your mother had from her farther *or* mother, but most likely is some mix of the two at a non-fixed ratio.",
"Each human somatic cell has twice the DNA required. Eggs and sperm undergo meiosis in which their DNA is split in half. They are in the haploid state. Mitochondria are different. You inherit your mitochondria and your mitochondrial DNA from your mother only since it is a cell component. Genes are located on chromosomes. Genes close together on the same chromosome are likely to be inherited together. But this is not always the case. Genes are mostly dominant or recessive. They can also be codominant. You have two genes for each trait. Either a dominant gene will be expressed over a recessive gene or if two recessive genes are present the recessive gene will be expressed. You have a fifty fifty chance of inheriting either gene from a parent. Either the one expressed in the parent or the other. But you will get half of your DNA from one parent and half from the other. With 46 chromosomes it is highly unlikely that you will inherit similar DNA far from the 50 per cent average. when compared to a sibling."
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7cy0h9 | Why do people want to sleep after they finish eating? | Biology | explainlikeimfive | {
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"text": [
"Your body is using energy to digest all the food you took in, so there is less energy availible for other activities. Low energy levels lead to inactivity and eventually sleep."
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7cy0rh | What's the difference between a trademark, copyright and patent? Could they not just be one broader thing? | Other | explainlikeimfive | {
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"A trademark is a word, phrase, symbol or other imagery that identifies the source or ownership of some set of goods. They do not expire. Other people are allowed to use or reference your trademark, so long as they are not trying to deceptively claim to be or be sponsored by the trademarking organization. A patent right over some invented property, such as a machine, industrial process, or chemical composition. They expire after 15 to 20 years. You need permission to use someone's patented device. A copyright is control over some body of work, giving them control over how the work is distributed and copied. You need to permission to copy or use copyrighted work, or otherwise fall into narrow categories of exception. Copyrights last for the life of the author/creator plus 70 years (with some different rules for corporate copyrights).",
"A patent is for an invention. If you invent a new type of thing, or a unique way of doing a thing, you can get a patent for it, which gives you exclusive rights to make and sell those things for about 20 years, after which everyone can start competing with you. For example, you might patent the telephone, if you invented the machinery and techniques for converting sound into energy and transmitting it along a wire, then restoring it to sound, directing it along wires according to number signals. For 20 years, no one else is allowed to make or sell anything similar to that. It doesn't matter if you're only making flip phones but someone wants to sell smartphones: you own the rights to, essentially, the idea of a phone. A copyright is for a creative work -- a novel, a song, a movie. If you have a copyright, no one else is allowed to print their own releases of your novel, or make a movie based on it. In most countries, it lasts for your entire life plus 70 years if owned by a person, or 50 - 95 years if owned by a corporation (since a corporation can't die). Obviously, though, you don't own the rights to the *ideas* in your novel. Other people are free not only to write novels, but to write novels inspired by or similar to yours, as long as they're not just reprinting your text and moving stuff around (so you're totally free to write your own series about a British boy who goes to wizard school, or your own movie about an orphan farmhand who uses psychic powers to blow up a space weapon). A trademark is something used to uniquely identify your business. You can trademark colours, 1-word slogans, shapes. But they only apply within your industry/market, and only exist to ensure no one else can try to trick customers into thinking their business is yours. They last forever. For an example, say you own a beer company, and all your cans are bright solid pink with no prominent logos or patterns on them. You become huge and successful and everyone loves your beer, and because no one else is selling beer in bright pink cans, the colour/design becomes kind of iconic. Then someone decides to cash in by releasing their own shitty beer for half the price in a bright pink can. It goes onto store shelves across the aisle from yours. Their whole business model relies on people not looking too closely and mistaking their stuff for yours. In that context, you could have a trademark on the colour bright pink, because it identifiers your product, and you could sue them for infringing on it. And you could have that trademark for 500 years. But it would only apply to beer cans, maybe to drink cans in general, but not to say delivery trucks of the same colour, or shoe company logos, because obviously people aren't going to confuse your beer with the trucks or shoes. To be a trademark something has to be distinctive enough that it identifies you to customers, usually a logo or logo-concept (like a big curvy yellow M for McDonald's, or a swooshy tick for Nike), and for something to infringe on a trademark it usually has to be said that there's a clear attempt to piggyback off your brand. So the three things exist for different reasons, and they wouldn't really make sense to be the same thing. It doesn't make sense to only own your company name/logo for 20 years. But you don't want one person to own the idea of a telephone for eternity either, you want to give them a while to make money off their idea but then open it up for competition. And if someone writes a novel or makes a movie, you don't want them to own the *ideas* in their movie, just the actual creative work of it. And there are some tie-in concepts that relate only to one thing and not the others. Example: with copyright, there's something called 'fair use', which says that you're allowed to reprint bits of a novel or screen bits of a movie if it's in certain contexts, like a review, or to distribute copyrighted photos as long as it's only within a school in an educational context. If you just have one concept for all these things, then by the time you add in all the legal clarification for when certain exemptions apply and to which things, people will be asking \"why don't we just simplify 1 super complicated thing by making it 3 simple things?\""
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7cy2ra | why do animals taste different? | Is it because of the fast/slow twitch muscle fibers being present in different amounts per each animal? Or is there much more to it? Just wondering why cow meat and pig meat would have a different taste | Biology | explainlikeimfive | {
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"There is more to it than just muscle fiber type. Muscle fiber type would explain differences in different cuts of meat from the same animal better than it would explain the differences between species. Here's a link to a previous [ELI5 thread]( URL_0 ) that goes into more detail."
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7cy35p | Why are there so many centenarian in Japan compared to other countries? | Biology | explainlikeimfive | {
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"It usually attributed to the culture around food - their diet consists of vegetables and greens, lots of fish, and reasonable portions. They also are not a car culture, using public transportation which often involves walking quite a ways on a daily basis, and often have organized calisthenics or other exercises during breaks during work or school.",
"Two reasons: The okinawan diet (check out the okinawan food pyramid) and japanese culture. Firstly, the japanese avoid meat and eat fish daily. Very rarely do they eat pork. Then they eat lots of vegetables and their main form of carbs are rice and sweet potatoes (which are amazing antioxidant and slow digesting, full of fiber compared to regular potatoes). They eat soups with herbs/fungi/mushrooms which also provides antioxidants. They also have a lot of variety in their diet, they don't eat the same fruits/veggies/foods/herbs. The variety provides them with various antioxidants. What is an antioxidant? Well just like iron rusts over time because of air, your body rusts because of oxygen. antioxidants prevents the damage that oxygen can do to your cells. They also eat around 500 calories less than the average american. But not because of smaller portion sizes, instead because they spend their calories on better food. For example, 500 calories worth of rice, salad, fish then 500 calories on a big mac. (plus, we eat fries & soda with our big mac so our calories spent on dinner are around 1000+) The other thing that helps is their sense of community. The elderly are not shipped off to a nursing home instead they live with their family and continue pursing their hobbies or passions. There are actually groups of old people who volunteer together, garden together, and walk together. This sense of community helps them fight off the depression, and gives their life purpose to continue living happily and healthily. The Mcdonalidzation in Japan is proof that diet greatly affects longevity. People in okinawa before fast food lived up 90-100 WITHOUT HEALTH PROBLEMS, but now the younger generations are suffering from obesity/diabetes/health problems in their 60s."
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7cy64i | A person gets in a bad accident that requires and gets a blood transfusion. Shortly after, that person commits a crime, gets wounded, and leave blood trace at the scene they fled. Who's blood would show up on the DNA analysis? | Biology | explainlikeimfive | {
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"text": [
"the DNA in blood comes from the white blood cells. the red blood cells which is used for transfusions contains no DNA at all. so you won't get both people's DNA showing up."
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7cy7lj | Why is the Sahara a desert when other places at the same latitude are tropical rainforests? | Other | explainlikeimfive | {
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"Look across the United States, if you draw a band across the US centered around San Francisco, CA. Coastal community, fairly foggy and cool year round. Nothing like the climate in Salt Lake City, Denver, and so on. Latitude, geography, wind patterns, proximity to the ocean plus others are all factors in the weather patterns."
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7cycgr | What is the difference between Anti-Malware and Anti-Virus? | I have heard of both Anti-Malware and Anti-Virus and didn't actually understand the difference. I have had some more tech savvy friends suggest either of them based on any issue I face. What actually is the difference between them and which provides the most comprehensive protection and which one is most important to have to protect our personal computers and PDAs? | Technology | explainlikeimfive | {
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"text": [
"Branding, mostly. Technically speaking, malware is an umbrella term for all sorts of malicious software. Viruses are a type of malware - specifically, a virus is a piece of code that copies itself into a file so that when you open the file, the virus's code is executed (which can do malicious things, as well as inject itself to other files on your computer). Today, \"virus\" is often used to describe other kinds of malware such as worms and trojan horses, despite the term being inaccurrate, and \"anti-virus software\" protects against various types of malware, not just viruses, but the name stuck. \"Anti-malware\" is actually the more accurate term."
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7cyhrm | How does the brain store information/memories? | Does it store it with a chemical coding that's decoded when the information is recalled, or is electrically, closer to how computers store memory? | Biology | explainlikeimfive | {
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"No easy way to answer it. The current understanding, in a nutshell, is that memories are basically groups of neurons that fire together preferentially. So, unlike computer memory, where a bit is moved to a 1 or a 0 state permanently, memories in humans brains are thought to be groups kf neurons which have been conditioned (or potentiated) to fire together. A stimuli causes your brain to perceive it by firing a set of neurons. Repeating that same stimuli causes the same group of neurons to fire repeatedly. This is where Hebb's postulate says 'cells that fire together wire together' From what I know, nobody has physically been able to see these synaptic pathways strengthening, or weakening. This is just a theory at this point.",
"Neither. They are stored by 'rewiring' the neurons that fired together to create the experience. If a memory forms long term, these neurons are now 'consolidated', meaning that they are now connected together more intensely than they were originally. The activation of this memory now become easier as the group of neurons that formed the memory are now primed to talk to each other. The neurons usually aren't all bunched together in the brain, but spread out across it. All of this requires the hippocampus which helps consolidate short term memory into long term. Pathways are created between the neurons that fired and the hippocampus to create a short term memory, then back to the original neurons if the memory is meaningful enough to become a long term one. For additional info on what consolidation actually is, there are two types involved in memory formation: 'synaptic' and 'systems'. Synaptic is at the neuronal level, where synapses are formed or strengthened to allow two neurons to talk to each other. Systems is at the level of the whole memory and is where the memory is moved from the short term (in the hippocampus) to the long term (in the rest of the brain)."
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7cyk0o | Why when some people are about to engage in a physical altercation do they start to shake, heart pump and lose peripheral vision? | This includes myself and a few friends/family members I know. The loss of vision I’ve always thought of it as tunnel vision but never understood what causes it? | Biology | explainlikeimfive | {
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"Your body has some really complex biology, and it is very, very good at helping you survive. The reactions you are talking about, like increased heart rate and dilated pupils, as well as tightening of the bladder and the release of hormones like epinephrine, are caused by this really cool thing called the sympathetic nervous system. This system is responsible for things like your \"fight or flight\" response, and it triggers based on stress and perceived danger. It's purpose is to give the body a better chance at survival, which it does by doing what amounts to overclocking your body. This is bad for you long term, but it may just help you survive the short term. When you are no longer in danger, your parasympathetic nervous system kicks in, undoing pretty much everything the sympathetic had just done. Edit- Typo. Sorry",
"These are side effects of adrenalin, a hormone your body secretes to prepare you for a fight or to run away.",
"The magic of adrenaline (and a few other chemicals) and a deeply ingrained fight/flight system that's built into the lower levels of your multi-layered brain. When your brain realizes you're in a dangerous situation, it triggers the release of adrenaline into your bloodstream, which energizes you and focuses your mind on staying alive. Your vision focuses on what you need to do to survive, and your reflexes are charged up compared to normal. Your heart pumps more blood to get ready for a massive burst of exercise. It's basically like when you're playing Mega Man and the boss's hit point meter charges up to maximum, because that game is hard but it turns out deep down those minibosses are scared of you."
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7cyku3 | since people with higher metabolisms are turning more energy stores into usable energy, do they have more energy? | Confused about this | Biology | explainlikeimfive | {
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"There's a lot of confusion evident in this question. First of all, you're using the word \"energy\" in two different ways. \"Energy stores\" and \"usable energy\" both use the word in the same way, i.e., chemical energy generated by the body from food. This can be either direct from the gut to your cells, or be stored in the form of fat for later use. Either way, you're still breaking down chemicals derived from food you've eaten. But in the phrase \"do they have more energy,\" we're talking about something else entirely. A person's subjective sense of \"feeling energetic\" is not at *all* the same thing as chemical energy taken from food. Second, the idea that some people have \"higher\" or \"lower\" metabolisms is technically true, but not particularly *helpful*. A person's \"basal metabolic rate\" is the rate at which their body consumes chemical energy when at rest. In other words, the amount of energy you consume *just staying alive*. The issue here is that while muscle tissue consumes energy at a faster rate than \"adipose\" tissue (fat), a person with more *tissue* may well have a higher BMR than a person with less. So a morbidly obese man weighing 400 pounds is going to have a higher BMR than an Olympic athlete weighing 165 pounds, simply because there's *so much more* of him. Yes, muscle consumes more energy than fat, but not so much more that it can offset an extra few hundred pounds. So knowing a person's BMR, by itself, doesn't really tell you anything useful unless you also know their sex, height, and weight. Even then, it's not all that useful a statistic, as it doesn't vary all *that* much from person to person when you control for those other factors. Third, what people most mean when they talk about having a \"fast metabolism\" usually has more to do with how efficient the body is at extracting chemical energy from the food you eat *and* how efficient it is at storing that energy as fat. So it may seem as if *this* person can eat 5,000 calories a day and never gain an ounce of weight, while *that* person gains five pounds if he even *looks* at a cheeseburger. . . and we're really not all that sure why. Hormones definitely play a role, but exactly which hormones play what role, and how, is still being studied. Some people's bodies are just a lot better at those things than others. Genetics, age, sex, and physical activity all play a role (e.g., a lot of people find they start to gain weight around age 30), but again, those roles are not all that well understood. The micro-biome in your gut probably does too. But what's going on isn't really about \"turning more energy stores into usable energy\" nearly as much as getting chemical energy out of food in the first place and then storing it for later use."
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7cyyzj | Why do stationary cars shake from high speed passing traffic, yet pedestrians barely feel a breeze? | The obvious that cars are heavier than humans, yet a stationary car shakes or at least moves from high speed passing traffic, whereas a pedestrian on a adjacent sidewalk to the passing traffic, barely feels a breeze. | Physics | explainlikeimfive | {
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"Simple: Cars are closer to passing traffic. If you were a cyclist you'd realize the the air pressure wave effects you in the same way if you were as close to the traffic as cars are. Getting passed by an 18-wheeler going 60 MPH on a bike is a scary thing. (Before I get shat upon, lots of roads where I'm from are small country roads with 60 MPH speed limits because they're flat and straight for miles and miles.)",
"The shaking comes from a low pressure area being temporarily created between the stationary car and the passing car. As the moving car passes the stationary one, there is channel formed between the two cars. Because the moving car is dragging air along with it there is air moving through the channel which causes the pressure to drop. Now the air pressure on the outsides of both vehicles is higher than in the middle so the cars are pushed together. The reason this doesn't happen to humans is because they aren't shaped the same as cars so they don't form a long channel when the moving car passes by. There isn't nearly the same amount of surface area for the air to push the human towards the moving car.",
"The pressure change occurs more quickly as you effectively pass oncoming traffic twice as fast as a pedestrian does. This gives the pressure wave more 'power'. A car is bigger, the pressure difference has a larger area to work on so more total force is applied."
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7cz38z | When someone dies from burns, is it a direct result of the burns or complications caused by the burns? | I just read a story about a woman who died after suffering from second and third degree burns for three weeks. How does that happen? How do burns (which seem like something external) affect the body in a way that it cannot survive? | Biology | explainlikeimfive | {
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"While it is possible to have so much internal damage from burns that your body just fails, this will generally be so sever it will be (relatively) quick. What is more likely to kill you is dehydration, hypothermia, and infection, as your skin is vital for retaining water, regulating body temperature, and keeping pathogens out. Burns essentially destroy your skin.",
"Burns can have multiple effects on your system including shock. In truth the 'cause' of one's death is basically always lack of oxygen to the brain. This can happen as a result of anything that has an effect on the systems that carry oxygen into your lungs, infuse it into your blood stream, or carry it around your body. Severe enough burns can cause severe damage to all sizes of blood vessels(which carry oxygen) as well as cause your body to go into shock, which severely inhibits your body's ability to move oxygen around to different critical systems. Eventually there will be insufficient material to carry oxygen (blood loss), insufficient pathways to distribute oxygenated blood (vessel damage) or no pump mechanism to move the oxygenated blood around your body (heart failure).",
"It depends. Being burned can kill you instantly if it: Burns your lungs and you can't breath Destroys your body so you bleed to death Cooks your flesh or organs so they can't function. But you can die from burns much later by: Infections caused by open wounds from burned skin Dehydration caused by the body losing too much water without skin to hold it all in. Cellular damage flooding the blood with dead and dying cellular debris and toxins. The skin is an organ that protects us from infection, physically protects us from the environment, keeps the water and other things in our body from evaporating, etc. Just like damage to any other vital organ, if you damage enough skin to prevent it from doing it's job, it can kill you.",
"Usually there are two outcomes from whole-body burns: asphyxiation or systemic infection. Asphyxiation is basically your brain being starved of oxygen. This is usually the cause of death for house-fire victims because whole body burns can send you into shock. Fires usually mean smoke and heat, both things that are not good to breathe. So if you become disabled from the shock (loss of consciousness, for example), you suffocate. If you don't die from that, the circulatory system in the skin is now destroyed, leading to both blood loss and an incapability for your body to repair the damage. Left untreated it can lead to necrosis and bacterial infections, which causes a whole bunch of other problems. Systemic infection coupled with your body being overwhelmed with trying to repair itself can lead to organ failure, and eventually death. So, it could go either way."
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7cz5b4 | 'Modern humans' have existed for 130 to 300 thousand years. Why then do nearly all modern cultures seem to stem back no more than 6,000 years in origin? | Biology | explainlikeimfive | {
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"Because we spent a very long time pissing about in small little family units getting eaten by wolves and fornicating like primitive pre-civilization primates do. Civilization, or something that we could reasonably call the start of it, occurred around 12,000 years ago when humans finally stopped roaming in an area of the Fertile Crescent and started building stuff. This marked the break point where humans started living in larger and larger communities in a single geographic area. Slowly that led to the development of farming as a primary means of food production and the increase in food availability allowed division of labor which fast forward 12,000 years is why we both have computers and can sit here and talk on the internet.",
"The 300 thousand year old Modern Humans are genetically similar, but were still Hunter-Gatherer tribes. Generally speaking, every person was able to collect enough food for them and their offspring to survive. It was a full time job surviving, so there wasn't much extra that came out of it. Around 10,000 BC, we invented a nice thing called agriculture. By tending our own crops on our own terms, we were able to make it so a single person could produce the food requirements of many people. This is a pretty defining point, because it allowed for people to start doing other things than just surviving. Culture really starts from a little after this point.",
"shit snowballed after farming / domestication. suddenly you hade to fight for your land, make sure your own offspring inherited it, and folks got to get fancy new desieses like small pocks and karies.",
"The invention of agriculture changed everything. Suddenly our species was able to gather in very large groups without running out of food, *and* people had a big incentive to invest in infrastructure (things like government, roads, water supplies, writing).",
"Just because humans were human doesn't mean they had the ability to make written records, build permanent structures, or do anything which we associate with civilization. For a really long time humans were nomadic and did not cultivate crops or raise domesticated animals for food. Without that building structures or having large numbers of people staying in the same area was impractical.",
"Large scale sedentary human civilization was not, generally, possible without the development of agricultural techniques, which themselves took a combination of complex learning and artificial selection for domesticating crops/animals. Before this time, humans were, by and large, limited to relatively small groups where enough wild food could be gathered/hunted within walking distance to feed everyone. Too big a group, and you couldn't get enough food within the range people could travel. Additionally, you couldn't specialize. Bob couldn't be a teacher, he was busy getting food. Sally couldn't develop farming techniques, she was busy getting food. Note that agriculture is much older than your 6,000 year mark. However, human materials durable enough to survive thousands of years aren't necessarily common today, let alone in 15,000 BC, so many signs of it have been erased."
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7cz664 | What exactly causes this sharp pain we feel during wound contact with eq. alcohol, salt or citric acid? | Biology | explainlikeimfive | {
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"text": [
"Coincidentally, every thing you asked about has different reactions with the wound. In general, when you are wounded somewhere, your nerves in the area become hyper sensitive, most likely to alert you that you are injured so you can deal with it. So touching the wound with your finger will hurt on its own, because the pain receptors at the site of injury are especially good at detecting the contact with the wound. Now, salt: salt is really good and pulling out water out of cells. This is because water has the tendency to balance out the concentration of salt in all accessible areas. Since your cells are generally less concentrated than the pure salt on you skin, that means water will flood out until the concentrations are balanced. Your nerve pain receptors can respond to a lot of stimuli, and one of them is this increased concentration of ions as the water collects the salt and pulls it back into the cells Citric acid: Our body has a very good defense mechanism that prevents us from getting hurt or sick by things touching us. This super defense is called skin. When your injured, you have an exposed site where citric acid (like lemon juice) can enter your body. Citric acid is pretty acidic, and as a result, can lead to a lot of cell and nerve death where it comes in contact. Your body recognizes this as pain Alcohol: This one is actually super interesting. Alcohol doesn't actually trigger the same pain signal as salt or touching the wound does, it actually triggers the heat-pain signal in your body. Alcohol has the ability to make the heat response in your body a lot more sensitive. It's actually so sensitive that your own body temperature is warm enough to trigger a heat response, which your brain sees as a burning sensation. It's actually why alcohol might feel like it burns as it goes down, because your body thinks you're partially on fire"
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7cznq2 | How can other animals survive on one type of food but humans need a balanced diet? | Biology | explainlikeimfive | {
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"text": [
"We don't *need* them any more than other animals do, it's just that if you don't eat a balanced diet your life expectancy and quality of life will both be lowered. Animals can survive on one or two foods, but like us they'll be healthier if they get a diverse diet. Store bought pet food usually contains a mix of different foods for a more complete diet.",
"You feed your fish food that has already been balanced. You could totally live on one, and only one, specially formulated 'human mush' for the rest of your life. We don't want to, because that's boring and/or unpleasant.",
"Well, lets say you eat a steak, its only going to have protein and some vitamins but no calcium. If you ate a steak and the bone thats in it, you'd be getting both but no carbs. Now imagine a fish eating a whole fish, its getting the skin, the bones, the muscle, the organs. Its not specifically eating one part, its eating a whole prey that covers a lot of different nutritional needs."
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7czwek | Why is Bing so much worse than Google? | Technology | explainlikeimfive | {
"a_id": [
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"dpu1iby",
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"text": [
"a) google knows you better, has collected much more information about you and can therefore tailor search results to you b) google has much more users, allowing it to make more precise judgements about which results might be relevant for your query using historical query and click-through data",
"For the most part, it isn't. Several studies have been conducted that do blind comparisons of Google's vs Bing's results. Some favor Bing, some favor Google, but it's always competitive. Bing does not \"consistently\" display less useful results anywhere other than your pro-Google mind.",
"Google has been around much longer, and has been improving their algorithms the whole time."
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7czzcc | What physically ARE radio waves and what keeps different frequencies from interfering with one another? | Physics | explainlikeimfive | {
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"text": [
"Radio waves are light. You can see many different colors of light, right? That's because light comes in a lot of different categories called *frequencies* which correspond to their colors. Now, there's a lot of light out there you can't see with your eyes! BUT, a radio receiver can still \"see\" this light. Just like you can see that a red flower is red even if it's really bright outside, radio receivers can see the color (frequency) of the light they're receiving even with some background noise! If you were looking exclusively for a pattern of blue text, you would be able to see it even on a page full of pink text, right? Radio waves are the same thing.",
"[Radio waves are light]( URL_0 ), but at a much lower frequency, and light is photons. A photon has properties of both a particle, and a wave. So radio WAVES might travel like a wave, but they are also emitted like a particle, and they can travel through a vacuum, where normal waves like sound can't. The lower the energy of the photon, the lower the frequency it is. In high energy light we see this as blue for high energy, and red for low energy. If it kept getting lower and lower though, it would become infrared light, then radio 'light' all the way down. If it got more energetic, then it would move up through ultraviolet light, to xray and gamma ray light. Basically radio waves, visible light, xrays, etc, are all the same thing, photons, but operating at different energy levels (frequencies)."
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7d0556 | What is the slime that remains on clothes soaked for a long time? | Other | explainlikeimfive | {
"a_id": [
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"dpu9qif"
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"text": [
"Ick. You created a thriving habitat for micro-organisms such as mold and mildew to grow in. Throw out the water, rise the clothes twice, and wash the clothes twice -- preferably with bleach and/or hot water.",
"PLEASE Don’t mix bleach and ammonia.!!!! Take them outside and spray the slime off with a hose, or if you have a slop sink, spray them off in there—then Wash them with arm and hammer or some other baking soda brand to get the smell out. unfortunately, if mold got into the fabric, you may not be able to salvage them. You’ll see it as tiny black dots on any light or white clothes. Wash twice if necessary. Good luck."
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7d05wu | Why do french fries taste bad after they’re cold? | Other | explainlikeimfive | {
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"text": [
"Yer not alone in askin', and kind strangers have explained: 1. [ELI5: Why do french fries taste awful if reheated, but something like pizza is comparable whether fresh or reheated? ]( URL_4 ) 1. [ELI5: What is it about french fries that make them taste so bad when reheated compared to other foods like pizza? ]( URL_1 ) 1. [ELI5:Why do fries lose their taste after being refrigerated? ]( URL_2 ) 1. [ELI5:why do french fries, tater-tots, or any other deep fried potato food taste different after being left out or put in the refrigerator? ]( URL_3 ) 1. [ELI5: What is it about french fries in particular that make them nearly impossible to taste good once reheated in the microwave? ]( URL_0 )"
],
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"https://www.reddit.com/r/explainlikeimfive/comments/4nygy5/eli5_what_is_it_about_french_fries_in_particular/",
"https://www.reddit.com/r/explainlikeimfive/comments/66ftp4/eli5_what_is_it_about_french_fries_that_make_them/",
"https://www.reddit.com/r/explainlikeimfive/comments/50i51s/eli5why_do_fries_lose_their_taste_after_being/",
"https://www.reddit.com/r/explainlikeimfive/comments/2sqj0l/eli5why_do_french_fries_tatertots_or_any_other/",
"https://www.reddit.com/r/explainlikeimfive/comments/2jlv7x/eli5_why_do_french_fries_taste_awful_if_reheated/"
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7d069d | Why is it illegal to use tear gas on enemy combatants, but not on civilians in the US? | Other | explainlikeimfive | {
"a_id": [
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"text": [
"Because the US is a signatory of the Protocol for the Prohibition of the Use in War of Asphyxiating, Poisonous or other Gases, and of Bacteriological Methods of Warfare (aka the Geneva Protocol) that outlaws the use of chemical weapons in warfare. It does not address the use of irritant gases in civil settings.",
"Because tear gas falls under the definition of a chemical weapon. Also, an army has less accountability that a policeman, so you want to set a higher standard. There is a lot of grey area between tear gas and something that can kill you, and you don't want countries getting cute with that distinction. A policeman that used more than just irritating tear would face criminal charges, and the department a massive lawsuit."
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7d0ncv | Can atoms touch? | Physics | explainlikeimfive | {
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"text": [
"Define \"touch\". Ordinarily, atoms repel one another due to the electrons having similar charges, but atoms can sometimes bond together through their electrons as well, sharing (certain) electrons with one another, which could be thought of as \"touching\" since the two atoms are basically joined at the shared electrons. Of course, you can also fire a nucleus at an atom at very high levels of energy in order to break it apart and cause a nuclear reaction, such as a nuclear explosion.",
"Yes. Electrons on the outside of atoms repel each other, just like magnets. So, usually, they don't touch. If you managed to speed the atoms up enough so that it made it past that, the protons inside the nucleus would do the same thing to each other. But if you got them close enough, there's something called the \"strong\" and \"weak\" nuclear forces. They're a lot stronger than the force from charges, but they only work at really, really, tiny distances. That would make them stick together, and make a new bigger atom. We call that \"fusion.\" If they're fast enough, they'll break up like billiard balls. That's \"fission.\" You either need a lot of heat and pressure, or a lot of speed to make that happen. The sun uses heat and pressure. Supercolliders use speed."
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7d0pkm | How are you able to hear where footsteps or gunfire are coming from in videgames? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Your brain is really, really, good at figuring out where a sound is coming from, based off of the difference in how each ear hears the sound. Video games use this to make the sound louder or softer in each ear to trick your brain into thinking it comes from a specific direction. There's a limitation to this. Here's an experiment to try. Put on a blindfold, and have a friend use something to make a sound around your head. Tapping two things like spoons together works. You'll be able to tell if it's to your left or right easily, but if they make the sound right in front or behind you, you won't be able to tell. The sound is equally distant from each of your ears, so your brain has to use your sight to help. We use a combination of sight and sound to figure out where a sound is coming from, and video games give us both.",
"> How are you able to hear where footsteps or gunfire are coming from in videgames? There are a variety of ways in which we can locate sounds. Most obviously is volume; if the sound is louder in your right ear than your left it indicates the source of the sound is somewhere to the right of your head. Another major way to determine the location is a very slight delay in when the sound is heard between the ears. Sound travels through the air at a finite speed so it won't arrive at each ear at exactly the same time. Our brains can actually detect the slight delay between our ears and provide a direction based on that. Both of those factors can be reproduced through headphones by a computer. A third way we can locate sounds is due to the shape of the pinna or outer ear. The funky shape of our ears isn't just for show, it actually blocks or bounces incoming sound and subtly changes what comes into our ear canal. Our brains can pick up on these tiny changes and from experience match them to directions of sound. If you change the shape of your pinna then it can take a week or two for your brain to learn how the new shape alters incoming sound, but it will eventually start to match directions again. Reproducing this effect when using headphones is much more difficult but games can apply a generic alteration to sounds from certain angles which your brain will eventually learn to recognize."
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7d14k2 | Either the universe continues indefinitely, or it has an edge somewhere, both boggle the mind to imagine, which is correct? | Physics | explainlikeimfive | {
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"We may never actually know! From our position in the universe, there is a distance away from us that is expanding away from us so quickly that no light (and thus no object) could possibly reach Earth. That distance defines the observable universe, and that is much smaller than the size of the universe itself. This isn't just a \"we can't see past this boundary right now\", this is \"it is physically impossible to reach this boundary from Earth... ever\". So the takeaway is that it *literally* doesn't matter whether or not the universe is infinite beyond that point, because it will *never* affect us in any way.",
"No one knows. But since you say that both options are mind-boggling, I'll try to deboggle you. Infinite: because of the speed of light limit, it doesn't matter what's happening very far away - at least not for a very long time. Each part of the universe is doing its own thing, so it doesn't make much difference how many parts there are. Has an edge: you're made of a huge number of atoms. You think of yourself as a single being, but you know that if you perturb your atoms too much, they will rearrange themselves to the point that you will no longer exist, even if they still do. At the edge of the universe, there would be physical laws (called boundary conditions) governing what would happen to the atoms there. Maybe they'd bounce off the edge. In that case, you would bounce off the edge, or go splat, depending on how fast you were moving. Maybe they'd bounce back as antimatter. In that case you would explode. Maybe they'd just disappear. There are a lot of possibilities, but it isn't fundamentally different from hitting anything else.",
"There's a third option of finite but closed, and so without edges. Like the surface of a balloon.",
"Sort of like finding the edge of earth, no matter how far you travel, you’ll never find an edge for earth and you might even end up where you started.",
"While it is impossible to confirm, to the best of our knowledge the universe is infinitely large. > [We now know (as of 2013) that the universe is flat with only a 0.4% margin of error. **This suggests that the Universe is infinite in extent;** however, since the Universe has a finite age, we can only observe a finite volume of the Universe. All we can truly conclude is that the Universe is much larger than the volume we can directly observe.]( URL_0 )",
"If I blow up a balloon it's expanding in the air, in my city, in my state, in my country, on Earth. So what's the universe expanding into? Nothingness?",
"In a way, maybe the universe is round/spherical ? Maybe if we go far enough, at some point we'll be back to the start. We used to think that earth was flat and that we had to explore its infinite lands. Well, turned out it was round the whole time."
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7d15go | Why do people sometimes throw up/feel like throwing up after intense exercise/physical activity? | From what I understand it has to do with the blood leaving your stomach to go to other areas of your body - I'm assuming whatever area you're working out - but why does that cause nausea? And how is that helpful? | Biology | explainlikeimfive | {
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"text": [
"When you go through exercise, your sympathetic nervous system mans the helm. It's the fight or flight portion of your brain, and generally hinders any relaxing functions. When any exciting stimulus is exposed to the body, this system does a number of things. It dilates pupils, contracts blood vessels, makes you more wary, more awake, and it slows the processing of food in the gut tube. This whole process diverts all the unnecessary energy use in the body towards dealing with the stimuli. This is best done in small bursts, over doing it could have a number of unhealthy side effects, like vomiting. I hope that helps!"
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7d17kp | Why is it that the area of a sphere (4 pi r^2) and the area of a circle (pi r^2) differ by a factor of 4? | It seems really weird that it's such a normal number. Is there an intuitive explanation as to why this is the case? Is there an easy way to map four circles onto the surface area of a sphere of the same radius? In before someone helpfully informs me that the proper terminology is the "area of a disc," and the "surface area of a sphere," and that I misused the term "differ" and should instead prefer using "ratio." And that 4 isn't actually a "normal" number, because a "normal" number is something different. | Mathematics | explainlikeimfive | {
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"text": [
"That the surface area of a sphere is four times the area of a circle of the same radius is \"coincidental\". 4pir^2 is the first derivative of the formula for the *volume* of a sphere: 4pir^3 / 3. This sorta makes sense if you think of an infinitely small rise in r as being a infinitely-thin shell around the sphere, which is what the surface area is."
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7d17p1 | How does new money enter circulation in the United States? | Economics | explainlikeimfive | {
"a_id": [
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"text": [
"Depends on how you define \"money\". I'm not trying to be cagey, but cold hard cash is only one type of money. Economist recognize other types of wealth creation as adding \"money\" to economy. (M0, M1, M2...see wiki links below) example: you put $1,000 into the bank. The bank then loans that money out to a business. There is now, in effect, $2,000 in the system. The $1,000 in cold hard cash, and the loan, which is worth $1,000 dollars. Now that business uses the money to pay it's workers that month. The money goes into the employee's bank accounts (back to the bank). The bank then loan the SAME $1,000 to another business - and now there are TWO loans...the bank has CREATED two thousand dollars (in loans) ...which can be bought and sold on financial markets. wash, rinse, repeat....most of the money in circulation is actually money created by banks - this is the real reason why governments bail out the banks...they keep the economy expanding by \"creating money\" without printing new bills. This is VASTLY oversimplified for ELI5 for more information: URL_0 URL_1",
"Most money are bank deposits/bank liabilities. That money is created when banks make loans to customers. If you borrow $100 000 from a bank to buy a house for example, the bank creates that deposit out of thin air. This becomes a liability for the bank. At the same time the bank receives a claim on you to pay back those $100 000 some time in the future plus some interest. Or to put it another way, banks do not lend deposits. Instead it's the lending that creates those deposits, or as the Bank of England puts it: > Whenever a bank makes a loan, it > simultaneously creates a matching deposit in the > borrower’s bank account, thereby creating new money URL_0 Then there is physical money. All physical money is created by the Federal Reserve in the US. Physical money is then \"bought\" by banks to satisfy customer demand for cash. The amount of physical cash is however small compared to the amount of bank deposits."
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7d1cjt | Why does regular water taste different from water that has melted from ice? | Is it an excess of hydronium or hydroxide ions that give it that taste? | Chemistry | explainlikeimfive | {
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"text": [
"Yer not alone in askin', and kind strangers have explained: 1. [ELI5: Why does melted ice taste different than regular water? ]( URL_2 ) 1. [ELI5: Why melted Ice Water tastes different from the Water that was used to make the Ice. ]( URL_4 ) 1. [Why does water from melted ice taste different than the same water that wasn't frozen? ]( URL_5 ) 1. [ELI5: Why does melted ice taste slightly different than tap water? ]( URL_7 ) 1. [ELI5: Why does water that came from melted ice cubes taste different than regular water? ]( URL_1 ) 1. [ELI5: Why does water taste different after you freeze it? ]( URL_0 ) 1. [ELI5: Why does water taste weird after ice has melted in it compared to water without? ]( URL_3 ) 1. [ELI5: Why does tap water taste fine, but when made into ice cubes and then melted it tastes weird and awful? ]( URL_6 )",
"Water tastes like trace amounts of metal ions. When you freeze water some of the metals precipitate out. The water you freeze and defrost thus has less metal in it and it tastes different. so neither H+ nor OH- give the taste."
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"https://www.reddit.com/r/explainlikeimfive/comments/6vsbqa/eli5_why_does_water_taste_different_after_you/",
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7d1cqw | Adrenaline: I get how it works, but I don't get how some of us (like me) enjoy the rush, and others don't. | Biology | explainlikeimfive | {
"a_id": [
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"text": [
"Adrenaline is accompanied by other hormones. One type, called endorphins, decreases our pain response and makes us feel good. It's like nature's morphine. The other one, called cortisol, is a response to stress. It makes our body better able to handle rough situations, but it's not pleasant. It can also do damage to us if they stay in the body too long. We like pleasant feelings, and we don't like unpleasant feelings. Endorphins are pleasant. Cortisol is unpleasant. We all get \"trained\" to like things that release pleasant hormones, and to avoid things that release unpleasant hormones. Everyone has a different reaction to specific situations. Some people get more endorphins. Some people get more cortisol. Adrenaline increases both, but at different rates. Physiology, past experiences, personality, and mindsets can influence how much of one you get over the other. People who hate an adrenaline rush can become thrill-seekers, and adrenaline junkies can start freaking out about everyday situations. It's all about stimulus and response."
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7d1kba | Why does water taste so terrible after eating an apple? | Biology | explainlikeimfive | {
"a_id": [
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"text": [
"The answer is a lot easier than you think. Apples, while brimming with water, are also chocked full of sugars. Tasting that sweetness before a drink of plain water is comparatively bland. Our bodies are built to prioritize simple sugars and fats, so it's only natural our senses hold bias towards them."
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7d1lj7 | Why do siblings (especially sisters) often have very similar-sounding voices? | My sister and I have very similar-sounding voices, to the point that if I call my mum and she doesn't look at the caller ID before answering, she can't immediately tell which of us is on the other end. I've noticed this many times before with other women and their sisters, but less so with male siblings. Is there a biological explanation? | Biology | explainlikeimfive | {
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"In terms of speech development, kids would pick up similar linguistic patterns/idiosyncrasies from parents most but from those who speak around the kids.",
"The sound of your voice is caused by the physical structures of your body, particularly your throat and nose. You probably look similar to your sister, therefore you probably have similarly sized and shaped vocal cords and other physical structures. I have a more nasal voice than my sister does because my nose is physically shaped differently (I have a deviated septum and she doesn't); meanwhile my dad and my brother, who are of similar heights and are strikingly similar in appearance have almost identical voices."
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7d1xda | If carbon dioxide is bad for you to inhale, and people provide it when you breath out, Wouldn't the carbon dioxide do any damage to the person getting mouth to mouth? | Biology | explainlikeimfive | {
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"Carbon dioxide doesn't hurt you. A lack of oxygen hurts you, and carbon monoxide hurts you. You don't convert all the oxygen you inhale into carbon dioxide, so CPR is still effective. However, these days, heartsaver CPR is recommended (unless you have special training and two people). This uses the chest compressions to move some air through the lungs while also working the heart. It doesn't involve breathing into the person's lungs.",
"It's not enough to cause harm. Your exhaled air is still quite high in oxygen, and is *much* better for the other person than no breathing."
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7d286g | Why is it important to do stretches before exercising (i.e. pull-ups, push-ups, weightlifting, etc)? | Biology | explainlikeimfive | {
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"When people use the word \"stretch\", they typically mean \"Static Stretching\". Modern research shows static stretching before exercise is actually a bad idea. It has been shown to reduce muscle power performance, while providing limited (if any) injury reduction. However, \"Dynamic Stretching\" is good. Dynamic stretching is basically what people call \"warming up\". Things like: arm circles, leg swings, easy lunges, etc. citation: URL_1 **Edit/Update**: Oh god...this is by far my most upvotes. Now I feel obligated to give proper information. It turns out, modern-modern research suggests incorporating some static stretching into an overall warmup routine can be beneficial citation: URL_0",
"I remember reading that a pretty comprehensive study was done, and people who never stretched, and people who always stretched, had almost identical injury rates. People who sometimes stretched, but sometimes didn't bother however, had far more injuries than the other groups.",
"Stretching is a controversial topic. It isn't clear that it does anything. There is research which shows it can be good. There is research which shows it can be bad. There is research which shows it does nothing. Really, more research needs to be done on it. But as for now, the scientific landscape is a little too rocky to have any firm footing, so I recommend waiting until there is some sort of expert consensus from the sports and performance experts. Stretching does need to be differentiated from warming up. It is probably important that someone who benches 315lbs warm up prior to benching and not just go into benching 315lbs cold. One big reason is because the level of technique needed to bench 315 tends to be pretty high and the margin of error is low, so it is generally good to prepare for the lift by ramping up to it. When it can get a little confusing is that many weight lifters will do a lot of stretches to improve their flexibility. For them, having increased flexibility is important because the positions that they need to get into in order to perform maximally require a great deal of flexibility.",
"It is NOT important. Warm-up is important. Stretching before exercise causes more problems than it solves. Stretching after exercise is beneficial.",
"I read somewhere that it is actually better to stretch days prior to heavy work outs. When you stretch you make micro tears in your muscles and ligaments. Giving your muscles the time to heal after stretching gives you the benefits of stretching without putting you at risk of injury. It may be beneficial to have a stretch day in your work out regimen and then **warm-up** before each workout.",
"As others have already said, there's a lot of debate but generally it's agreed that warming up your muscles is better than doing serious stretches first thing. A point of interest- people who are hyperflexible/double-jointed should use extreme caution when stretching and should consider restraining themselves to only doing the dynamic warming up variety. The last thing you want when your joints are loose is to loosen them further. Voice of painful experience here, it can lead to regular and random dislocations and subluxations later in life.",
"I will give you a simple answer: stretching before work-out is not a good idea as it creates micro-tears in your muscle and compromises performance when doing heavy duty lifting. Here is when stretching is actually beneficial: long-term. Stretching will allow blood to flow into your damaged muscle and allow more better development and flexibility long-term. Stretching essentially changes the way your pain-receptor picks up signals when muscle is elongated. Your muscle does not get longer.",
"Honestly? It's not. It's important that you stretch AFTER. A light warm up of some kind is all that is needed before a workout - 5 mins of light cardio, for example. This helps get the blood flowing and helps to \"prep\" the muscle for the imminent activity. If you want a good visual analogy, take a rubber band and put it in a really cold environment, like your fridge. It will be pretty stiff when you first take it out, so you want to warm it up and pre stretch it a little before you go trying to wrap it around something, right? Otherwise it might snap. The reason it's important to stretch AFTER is because at the end of a workout, after contracting over and over for a prolonged period of time, your muscles are shortened. Ever do a bunch of bicep curls and then try to straighten your arm out completely? There's always always little bit of bend to your elbow, isn't there? If you don't stretch them out then this shortened state eventually becomes your new resting length for the muscle. This is why so many body builders are stiff as a board and yet other people can be as ripped as they are and still be able to do the splits. Source: Am licensed body practitioner.",
"it's actually not important at all. You'd be best just warming up, and a warm up is literally just a warm up for your muscles. And the best warm up for an activity is just to do that activity at a lower intensity.",
"I don't believe in it. You ever see a lion limber up before it takes down a gazelle?",
"**Do not stretch** before doing exercise because of increased injury. It's also a **huge waste of time** It is important to warm up. Warming up means doing a lighter version of your exercise, like walking before running and light weights before heavy. Warming up reduces injury by getting your body 100% ready for the upcoming exercise. You can further improve your exercise by massaging muscles regularly. Massage increases the blood flow and helps you relax. Tight muscles are weaker and can damage your skeletal system. Stay curious :)",
"Blood flow. Warm muscles to lessen chance of injury. Only quick stretches. Better to do a little cardio. Source- massage therapist and kinesiology fanatic",
"Proper stretching, as in increasing the flexibility of your body, is only useful if the exercise actually requires a lot of flexibility - e.g. martial arts. It should be obvious why you need to do that. For things like weight lifting the best warm up is to do the exact same exercise, one set, 3 or 4 reps, but with only 2/3 the weight. Do not stretch (as in pulling both ends apart, like when you do the splits) your muscles and ligaments before weight lifting, it does not help at all.",
"I haven't seen an actual answer to the question so I guess I'm up. As you probably have heard, there are different kinds of stretches that do different things. You want to warm up before working out because it calibrates your body and prevents injury. You warm up with dynamic stretches that should aim to ramp up to your full range of motion. If you don't do this, ie you don't ease yourself into your maximum range and just go 0-100, you likely will hurt yourself. Here I'll include an example. I've been working on handstands a lot recently. For a while I hated doing them because they hurt my wrists. I even would warm up! But then I discovered more wrist warm ups that target different parts. Now before I practice, I warm up my whole body as per usual, and then spend an extra 5 minutes doing more wrist warm ups, like finger push-ups, flashlights, and wrist rolls. When I wouldn't warm up I would usually hear a click when I was upside down with my whole weight on my wrists. It would sound like I cracked a knuckle, but it would hurt a bit. Now that doesn't happen usually. All because I warm up. Static stretching is great for a different reason. It helps your muscles recover from heavy use. Don't warm up with it, and don't do it when you aren't warm. In fact it's great for cooling down. If you want to improve your flexibility, try isometric stretching, or resistance stretching. This is where you resist some weight in a comfortable stretch for maybe 30 seconds, and then when you stop resisting you see your range increase a lot. These are best done with a partner who knows what they are doing. Source? Eh I stretch a lot. Inflexible dancer dude.",
"I remember being taught in basic that stretching AFTER helped flexibility while before workout stretching was just warming or loosening up",
"It's not. There has actually ben a lot of evidence showing it hurts and can lead to increased frequency of injury.",
"It isn't important. What's important is having a comfortable range of motion for your joints that allows you to do whatever you are trying to do. Stretching helps you achieve this if you have limited ROM. Otherwise, there is no need to stretch before exercise. You should warm up though.",
"I have always warmed up just by gentle movements rotating shoulders, knee bends etc all over the body before exercise and it’s only after exercise do I stretch, static and dynamic (holding stretches for 30 secs or longer to improve flexibility. Think of it like an elastic band if you take one out the packet and stretch it, it’s likely to snap. Play about with it for a bit and gently stretch and increase it will get warm and you can stretch it more without it snapping."
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7d2lp2 | When a tree grows, where does it's matter come from? | Say I take a large glass box 100'x100'x100'. I fill it with soil and plant an acorn. The only thing that goes into the box is regular watering. Each season for 100 years, the tree grows larger, leaves are created and fall off and are raked up and stored. At 100 years the tree is cut down, the wood is dried and cut into planks. So, in the end, I have a pretty good stack of wood and bags and bags of composted leaves. Where did all that matter come from? Is there less soil in the box? | Biology | explainlikeimfive | {
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"Photosynthesis (light) + CO2 That's the easy explanation. But really it's more complicated than this if you want to deep dive into the specifics.",
"Most of the matter that makes up a tree comes from the carbon in carbon dioxide in the air. In a process called photosynthesis, a tree (or other plant) takes in carbon dioxide and uses energy from light that hits the leaves to separate the atom of carbon from the CO2 molecule. Those carbon atoms are then used to built parts of the tree. This is why deforestation contributes to global climate change. Trees store large amounts of carbon, and when they are cleared away more CO2 builds up in the atmosphere because the trees aren’t there to remove it."
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7d2qkg | Why does a higher air humidity cause us to sweat more? | Biology | explainlikeimfive | {
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"One of the ways our body regulates internal temperature is through sweating. The cooling effect comes by because when sweat evaporates it’s takes a little bit of the body heat away. On more humid days, the air around is more saturated which makes it harder for the sweat to evaporate. This means we don’t achieve the cooling needed, the sweat remains on our skin for a longer period of time, and we sweat more."
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7d2uzz | Encryption and decryption with prime number factorisation | I'm really good at math and I have a decent grasp of computer science. I understand that multiplying two prime numbers to get a huge number is easy, but checking out if a huge number has only two prime factors is a monumental task for a computer. What I don't get is how this is used for encryption and coding and decoding messages. I keep reading about this in books and they keep talking about how one side is the key or whatever but they never really explained how it all works. Every book seems to love explaining the whole large-numbers-take-a-lot-of-time-to-factorise concept but not how it actually works in encryption. I understand basic message coding--switch around the alphabet, add steps that changes a message into a mess of letters; then the recipient has to do all those steps backwards to change it back. How do prime numbers and huge numbers fit into this? How does knowing a pair of factors enable me to code a message and how does knowing the product enable my recipient to decode it? | Mathematics | explainlikeimfive | {
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"So, this kind of encryption revolves around [modular arithmetic]( URL_2 ). In modular arithmetic, you have some number called the modulus (\"M\"). Whenever you perform a certain arithmetic operation (such as addition or multiplication), you divide the result by M and keep the remainder. For example if M = 17 then 12 + 9 = 21 = 4 (mod M), because when dividing 21 by 17, the remainder is 4, and similarly 12 \\* 9 = 108 = 6 (mod M) because the remainder of 108/17 is 6. Certain operations in modular arithmetic aren't easily reversible. Normally, if I have two numbers n,y and I want to find the x such that x^n = y, then it's just a matter of taking the nth root of y to find x. However in modular arithmetic, if I have n,y and modulus M, and I want to find the x such that x^n = y (mod M) then there's no easy way of doing it - the easiest way is no better than \"guessing\" different values of x until we find the right one. It turns out that in modular arithmetic, the operation x^n is reversible if I know the prime factors of n (this is based on [Euler's theorem]( URL_0 )). This means that if I have n,y and M and I know the factors of n, then I can find the x such that x^n = y (mod M). So how do I use this to encrypt a message? I choose a pair of prime numbers p,q, and use them to calculate n=p\\*q. Then I also choose a large number M > n. So M,n are my public key, and M,p,q are my private key. Now, anyone can take my public key and use it to encrypt a message - they need to convert the message to a number x, and then calculate y = x^n (mod M) and send me the result. Since only I know p,q, only I can calculate the original x from y. **Oops! See edit below!** This is basically how the [RSA]( URL_3 ) encryption algorithm works. In reality, this system isn't used directly for encryption because it's too complicated, however it is used for [key exchanges]( URL_1 ) and [digital signatures]( URL_4 ). **Edit:** Oops! I made a terrible mistake. The number n=pq needs to be the modulus, not the exponent. The exponent can be (almost) any number. So you pick a modulus M=pq and a number e, so the public key is (M,e) and the private key is (p,q,e). Encryption is done by calculating x^e (mod M).",
"ELI5 version: All data is stored as numbers. Using \"*\" but it's not a multiplication of course, just to simplify. 1. Alice wants to send 5 to Bob 2. Alice does 5 * BobsPublicKey = 42 and sends 42 to Bob 3. Bob does 42 * BobsPrivateKey = 5 The key idea is to choose a mathimatical operation \"*\" where: - BobsPublicKey * BobsPrivateKey is an easy operation, meaning decoding 42 to 5 is easy - knowing 42 and BobsPublicKey, it would take a huge amount of computer power to find 5. Edit: bad naming",
"Other's have answered your specific questions. If you're interested in more though, I suggest The Code Book by Simon Singh. Warning - Simon Singh is a very addictive author, and you'll probably buy Fermat's Last Theorem and Big Bang pretty soon after. :)",
"In short: computers have difficulty factoring large prime numbers. Even extremely powerful supercomputers still take a very long time to factor large prime numbers. So by multiplying two very large prime numbers together you can create a very large non-prime number that will be very hard to find the correct factors for. The keys are the two prime numbers, the public key is the multiplied non-prime number. If a shortcut method was found to factor numbers faster with a computer, this form of encryption would no longer be effective. (And the person who found the shortcut would be a very rich/famous person)",
"Any chunk of data handled by a computer is technically just a number. This could be a file on a disk, or a string in a database, or a packet sent over a network, it's just a sequence of ones and zeros. Interpret that as binary, and you have a number. The simplest kind of encryption is that you have a secret large prime number. You multiply your data (which is a number) by that secret number, and you get a new \"encrypted\" number. Since, as you say, multiplying (and dividing) by large primes is easy but factorising is hard, anyone who gets hold of your encrypted number can't easily factorise it, i.e figure out what the two original numbers were (your secret and your data). But anyone with the secret prime can do a simple division and get the original data out. In reality, it's more complicated in ways that i don't even understand. The algorithms are much more complicated than just multiplying by the secret prime. There's one way hashes and assymetrical encryption with public and private keys. But to basic principle is that all of your data is a number, multiplying is easy and factorising is hard.",
"There's a lot of different things you can do with large prime numbers (and their product), since they have many interesting properties. The main idea is that you need to find some structural element that says something about the two prime factors of your large number, so that you can use the knowledge of those factors as a key to solving the encryption. Here is one simple example: If you look at numbers in modulo p (p being a prime number), for example, 7, you will find the following property: When taking the n-th power of every number 1, 2, 3, 4, 5 or 6, it will eventually loop around and return to the original number. 2^2 =4, 2^3 =1, 2^4 =2; 3^2 =2, 3^3 =6, 3^4 =4, 3^5 =5, 3^6 =1, 3^7 =3, etc. (modulo 7) The important part here is that this means that one step before you loop around, you will reach 1. If you try this out with enough numbers, you will notice that the length of every single loop is either p-1, or a number that divides p-1 (in the case of p=7, this means that all loops are either length 1, 2, 3, or 6). This brings us to the fact that, no matter which prime number \"p\" you pick, and no matter which number \"a\" you pick as your base, the following statement is always true: a^(p-1)=1 mod p. Now, from this, you can also prove a similar statement for the more general case if you don't have a prime number, but rather the product of two prime numbers N=p*q: a^\\(p-1)*(q-1) =1 mod N. Add 1 more to the exponent, and you will be back at your original a. And this is the important part for your encryption method. Let a be the message you wish to encrypt. All you have to do is openly give someone a public exponent (known by everyone) and the corresponding N that they should use to encrypt messages towards you. Everyone knows N, but nobody except you knows the factorization p and q. And in order to complete the loop, you can't use N, you need to know (p-1)*(q-1). So everyone has access to the tools they need to send you a message, but only you have access to the information needed to loop back to the original message. Note: I hope I didn't get anything wrong for the theorems, it's been a while since I looked into Field Theory, but this is the general idea how these things work. There are many theorems that describe a hidden property of N that depends solely on its prime factors p and q, and any such theorems are potentially useful for cryptography.",
"I want to lock my locker. I have a lock, but not one of those spin-it-right, pass 0, spin-it-left kinds of locks. My lock is a sort of combination lock. You know, the ones with the 0-9s on them? I go to the first dial and pick a 0-9, then go to the next dial and pick a 0-9, and so on until I have a combination, something like 2187, that is unique to my lock. My encryption lock is like this combination lock, but instead of a bunch of 0-9 dials, there are only 2 dials. And on these dials there are prime numbers, so many that you’d need a dial the size of a ferris wheel and numbers printed so small you’d need a magnifying glass to read them. Now, choosing a combination is easy. I take my magnifying glass and find a number on the ferris wheel. That’s my first prime number, which we call p, and the first number in my combination. I need another number, so I turn the ferris wheel some and use my magnifying glass to find one. This number is my second prime number, called q, and the second number in my combination. I take the lock, set the combination with my p and q, and lock my locker. I don’t need any more numbers, so I give the ferris wheel a mighty spin and everyone on it mighty motion sickness. I don’t know where my p and q are on the wheel anymore, but I wrote them down so I don’t need to search again. I also multiplied them together to get a third number, which we call n, that someone can use to make another lock just like mine. Just as I finish up, my friend Oiler who plays hockey in Canada walks into the room. Before he can ask how I got a ferris wheel through the door, I hand him a magnifying glass and say “Unlock my lock.” ELI5ing a topic like encryption is tricky. u/Schnutzel offered a great explanation that dives deeper into the matter. I had fun writing this so I hope you enjoy it and that I didn’t dumb it down too much.",
"The parts of [/u/Schnutzel's answer]( URL_1 ) that were about modular arithmetic and how logarithms work differently under modular arithmetic than in the real numbers were good. The part explaining RSA and factorization was very unclear in my opinion. As preliminaries for any encryption scheme, you first need to know how messages that you would want to encrypt would be interpreted as numbers. Skip the next few paragraphs if you do. Encoding messages as numbers relies on the same principle as the rough saying that \"everything inside a computer is a one or a zero\". A byte is 8 bits; there are 2 possibilities per bit; so there are ``2^8`` possibilities per byte. For two bytes, that's ``2^16`` possibilities. Three bytes, ``2^24``, and so on. I can associate each English character with a byte, and then turn English text intonumber as follows: \"A\" is represented by the number 97 (or 0x41 hexadecimal) \"B\" is 98 \"C\" is 99 So the string \"ABC\" is then ``97 + (256*98) + (256*256*99)``. So now that messages are numbers, we can operate on them using any other operation that we would perform on numbers. We can add 1 to our message number; we can multiply it by something else; we can use modular arithmetic, etc. On to RSA. RSA involves exponentiating numbers under modular arithmetic, which the [original post]( URL_1 ) explained well. For the moment, forget about the details about what the modulus -- the base of the modular arithmetic -- is. Just imagine for a moment that, for any particular modulus ``N`` that we had, that there were two numbers called ``e`` and ``d`` with the property that ``x^(e*d) == x (mod N)`` for any ``x < N``. I.e. we can take any number ``x`` less than ``N``, and if we raise it to the power of ``e*d``, then we get back ``x``. Then we could use this as a form of encryption. If I take a message ``m`` and raise it to the ``e``th power, i.e. ``m^e``, then whoever knows ``d`` can compute ``(m^e)^d mod N == m^(e*d) mod N == m mod N`` (because, remember, ``e`` and ``d`` have the special property that for any number ``x``, ``x^(e*d) == x mod N``). Whoever does not know ``d`` has to compute the ``e-th`` root of ``m^e mod n`` to figure out the original message, and this is hard for modular arithmetic. So that's the idea underlying RSA encryption. Mathematically speaking, we now need to know how we should choose ``N``, ``e``, and ``d``. There are two main concerns: 1) Workability as a mathematical concept: we need to be able to choose our ``N``, ``e``, and ``d`` in such a way so as to satisfy the condition I mentioned in the last paragraph: that for any number ``x`` less than ``N``, that ``x^(e*d) mod N == x``. That is the fundamental basis behind RSA encryption. 2) Security: it needs to be easy for us to generate values of ``N``, ``e``, and ``d`` that satisfy the previous property, and it needs to be difficult for anyone to figure out ``d`` -- the secret key -- based on ``N`` and ``e`` alone. If an attacker could easily recover ``d`` from ``N`` and ``e``, then they could easily decrypt encrypted messages -- obviously this is not something you want from an encryption scheme. So then, a bit of number theory / group theory helps us to ensure both of these properties. Three things are neeed. This will seem like I'm pulling a rabbit out of a hat, which I am, but bear with me for the moment because math is like that. 1) First, there is a number-theoretic concept called the [\"totient\"]( URL_0 ), which takes in a positive number N as input, and returns as output the number of numbers less than N that are \"relatively prime\" to ``N``, meaning that they share no factors other than 1 in common. So if ``N`` is prime, then every number less than ``N`` is relatively prime to ``N`` (so ``totient(N) = (N-1)`` in this case). Coincidentally, if ``N`` is of the form ``p*q``, where ``p`` and ``q`` are primes, then ``totient(N) = (p-1)*(q-1)`` in this case. That may seem weird, but if you know some abstract algebra, think about cyclic group decompositions. If you don't, ignore the last sentence. 2) Second, [Euler proved a theorem]( URL_2 ) stating that for any number ``N``, then ``x^(totient(N)+1) == x mod N``. Again, that probably seems weird -- if you know group theory, it makes sense -- but even if you don't, note the similarity to the mathematical property we were looking for above. We wanted to find two numbers ``e`` and ``d`` such that for any ``x``, ``x^(e*d) == x mod N``. This theorem tells us that we have one such number ``totient(N)+1`` that has the property we were looking for. Well, what if we could find two numbers, call them ``e`` and ``d``, such that ``e*d == totient(N)+1 mod N``? Then we would have what we were looking for in the first place! 3) Third. Let's generate two large prime numbers ``p`` and ``q``, and set ``N = p*q``. So we can compute ``totient(N)`` easily as ``(p-1)*(q-1)``, as mentioned above. Another bit of number theory tells us that, for any modular arithmetic system with modulus ``M``, that a number ``x < M`` has an inverse if ``x`` and ``M`` are \"relatively prime\" as mentioned in the first bullet point above. A number ``x`` \"having an inverse modulo ``M``\" means that there is another number ``y`` such that ``x*y == 1 mod M``. Furthermore, finding the inverse of ``x mod M`` is very easy, assuming we know ``M``. Putting all those points together. To generate keys in RSA: 1) Begin by generating two large prime numbers ``p`` and ``q``. 2) Calculate the modulus ``N = p*q``. 3) Calculate the totient ``totient(N) = (p-1)*(q-1)``. 4) Choose some number ``e`` that is relatively prime to ``totient(N)``. 5) Calculate ``d`` as the modular inverse of ``e mod totient(N)`` . 6) Make the numbers ``N`` and ``e`` publicly available. 7) To encrypt a message ``m`` using the public key ``e``, compute ``m^e mod N``. 8) To decrypt a message ``m^e`` using the private key ``d``, compute ``(m^e)^d mod N == m^(e*d) mod N == m mod N``. The security of this scheme depends upon not being able to recover ``d`` based on ``e`` and ``N``. Remember what we did to create ``d`` -- we first computed ``totient(N) = (p-1)*(q-1)`` based on its prime factors ``p`` and ``q``. Then, we chose a number ``e`` relatively prime to ``totient(N)``, and computed ``d`` as its modular inverse. If we knew ``totient(N)``, we could easily compute ``d`` from ``e``. However, computing ``totient(N) = (p-1)*(q-1)`` requres factoring ``N`` into its prime factors ``p`` and ``q``. And so, the strength of the RSA crytosystem depends solely on the integer factorization problem."
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"https://en.wikipedia.org/wiki/Euler%27s_totient_function",
"https://www.reddit.com/r/explainlikeimfive/comments/7d2uzz/eli5_encryption_and_decryption_with_prime_number/dpumq6g/",
"https://en.wikipedia.org/wiki/Euler%27s_theorem"
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7d2x6a | Since our bodies aren't 100% efficient at absorbing nutrients from food, wouldn't the nutritional information found on most food packaging be inaccurate, as not all of the calories, protein etc. are absorbed? | Biology | explainlikeimfive | {
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"The nutritional information on packaging is *roughly* accurate to the amount that the average person absorbs. The process is silly, and involves explosions and poop. Food is basically just fuel, and burning fuel can tell you how much energy was in that fuel. Scientists freeze-dry food, crush it into powder, and ~~explode~~ burn† it inside a machine called a bomb calorimeter. Reading the energy released by burning the freeze-dried food gives a general idea of how much energy was in that food. At the same time, other scientists feed that same food to people, collect their poop, and perform the same process. Freeze-dry. Crush. Burn. That gives an idea of how much energy a person does not \"absorb\" in the digestion process. Subtract one from the other. Total energy minus unused energy equals energy absorbed. Of course, this is a rough estimate, conducted for only certain foods. More complex items are just sums of the already-taken measurements for their component parts. [[Edit: Of course these are \"standard\" values and the amount absorbed by any individual may vary slightly based on their own unique digestive tract & the microbes living there.]] †: [[Edit for clarity: You are *setting up* an explosion by burning the material inside a constant-volume steel container—the bomb. Rather than allowing it to actually explode, the expansive force is contained and measured. My ELI5 language was a bit too simplified—it's my first time commenting here—so at the request of one of the replies I have edited.]] . . Source : URL_0",
"The amounts on the packaging are still accurate. This is why packages say \"the average adult daily energy intake is 8700kJ. Yours may vary\" or something to that effect. They can't account for individuals metabolism. But they can give exact measured amounts of what's in the food. If you know your metabolism well enough you can calculate how much/what to eat in a day by trial and error. Don't eat sugar 😉 Edit: changed to kJ. Forgot about you Yankee bastards 😂",
"It's safe to assume that raw ingredients have accurate nutritional specs. The processing (baking, frying, cooking, freezing, etc) of raw materials does have an impact on final specs. The larger the company the more likely they have the money/budget to extract more accurate results out of the final product whereas a smaller company with limited scientific resources or skills may have a product calculated based on raw ingredient specs without taking into account the processing. TL;DR: Take nutritional specs with a grain of salt. They exist to prevent scurvy and other nutrient deficiencies. Source: I do nutritional labeling in a small sized wholesale bakery.",
"There are so many factors involved that any such information is a very rough estimate based on averages. Especially in the case of raw produce, there will be fairly significant variation between one piece of fruit (for example) and another. So from the start nutritional information is an estimation based on measured averages and your particular purchase may vary to some extent regardless of how much effort was put into the measurements. How the food was stored, for how long, how you cook your food, what you've had to eat previously, the condition of your intestinal flora, how hydrated you are, the condition of your stomach lining and who knows how many other factors can all influence how many nutrients there are *left* to absorb and how many your body *can* absorb."
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7d32ed | Does Speaking A Foreign Language Change Your Personality? | Biology | explainlikeimfive | {
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"Learning a foreign introduces you to a new culture a way of thinking. It may not change your personality but it defiantly expands ones views."
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7d3ap7 | Is there another type of wave besides the fluctuations in the electromagnetic field and the ones in the "physical one"? | By physical I mean the sound, for example. Didn't know how to phrase it | Physics | explainlikeimfive | {
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"In quantum mechanics, all matter acts as a wave. There's a wave that describes the position and momentum of anything. You also have waves that describe groups of particles, including their interactions. For instance, a photon (a wave) can combine with the wiggling of the molecules in a piece of glass (the wiggling is characterized by waves) to create a new wave that's the combination of both. The combined wave is called a polariton, which is a particle that has mass, which is why light travels slower through glass than a vacuum.",
"Yes, the idea of waves appears elsewhere too. There are waves of traffic. URL_1 There are gravity waves. URL_0 There are ocean waves, which are not the same thing as sound waves.",
"If you classify waves according to *what* is oscillating, then I can think of three basic categories: waves of fluctuating electromagnetic field (light), waves of fluctuating spacetime (gravitational waves), and waves of moving matter (everything else).* But equally important is the \"restoring force\" which causes the oscillation to occur by pulling the whatever-it-is back towards equilibrium. There are probably dozens of ways this force can be configured, leading to dozens of kinds of waves. .* I'm not including quantum mechanical probability waves in this, because the Schrödinger equation isn't exactly a wave equation, but I'd be interested in knowing if I missed any categories."
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7d3cun | How does fast charge in mobile phones work? | Is it a kind of upgrade on the charger or on the phone? | Technology | explainlikeimfive | {
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"Both, and exactly how it works depends on the specific fast-charge technology. Most work by monitoring heat and cranking up the voltage as high as the system deems it safe to do so, possibly using multiple paths for the connection. Some instead (or also) raise the current used for charging. Either way, both the charger and the phone must support the specific scheme in use, or they'll fall back to the \"best\" scheme that they both *do* support - which might very well be all the way back to basic USB power delivery, which isn't fast-charge at all but is by definition supported on anything that charges over USB.",
"It usually sends a signal to the phone to see if it is compatible, if it is it increases the voltage from 5 volts to 9 or 12 volts at 2 amps. Higher volts at the same amperage is more power."
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7d3ft3 | How do automatic windshield wipers know when the windshield is wet? | Not to mention how wet it is. Edit: flaired as 'technology' because there's no 'black voodoo magic' option. | Technology | explainlikeimfive | {
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"There is a sensor on the windshield, usually translucide so you don't see the wires. This sensor act like a phone touch screen, it changes capacitance when water is rolling down on the windshield. this changes inform the onboard computer and automatically engage the wipers. Some also provide how much water there is. There is a few other ways to detect rain, Different brand will use different sensor technologies.",
"...cars have these? Either I'm broke or we're living in the future.",
"There is an optical rain sensor that is able to sense the droplets and turn the wipers on. Edit: Who the hell downvoted me? I do this for a living. Lol"
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7d3jh4 | Why can't the asteroid belt accumulate into one rocky planet? | Physics | explainlikeimfive | {
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"Its trying to, daily. But there's a problem. Jupiter is big. Like very big and therefore has a massive gravitational field. So whenever a group of asteroids start to come together Jupiter comes in and yoinks them apart. Along with the sun keeping them in orbit around it they don't really have an option but to stay in a belt until Jupiter stops being so greedy with its gravity well. If u were wondering, the same thing happens with Saturn, sort of. The gravitational pull of Saturn means that the asteroids in its rings can't clump together as they are ripped apart by Saturn's gravity",
"The asteroid belt is mostly empty. The asteroids are hundreds of thousands of kilometers apart, and it's quite wide, like 300 millions km if I recall correctly. The combined mass of all the stuff would be around 4% of the mass of the moon, which is quite low. For example Ceres, the asteroid-dwarf planet has around one third of the mass of the belt. With so little mass in such a big space, it would take billions of years for it to start collisioning and make bigger and bigger chunks until you have a dwarf planet, IF it was left to its own devices. But in addition to the little mass it has, the belt is quite close to Jupiter, whose gravity is strong enough to disturb the orbits of the asteroids and \"shepherd\" them, which completely prevents the formation of a planet or something there.",
"I think its less of a problem with Planets getting in the way, and more a problem of the reality being: asteroid belts are extremely spread out. On such huge scales that we use to look at them and how theyre shown in movies is completely unrealistic. Being so small and so far apart, they dont have the individual gravity necessary to begin forming a center, and so can't form a protoplanet.",
"There is literally not enough stuff in the asteroid belt to form a rocky planet. To accumulate you need gravity to do it's thing, but with so little material there's no attraction, and all the fluff in the belt is so far apart anyway that it'll never happen. I think all the material in the belt amounts to little more than our moon (I'm probably wrong on this exact point but for the purpose of ELI5 you get the point). I feel like that covers it, but ELI5 requires long answers apparently, so here's an extra sentence or two. I hope that the basics. It's literally because there's basically nothing out there."
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7d3lx9 | How does the human body know when to go into labor? | Biology | explainlikeimfive | {
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"Labor & Delivery nurse here! Aspiring mid-wife :) Progesterone is the pro-pregnancy hormone. When it's time for labor, the body releases prostaglandins (basically inflammatory signals) that will trigger the decrease in progesterone and increase in oxytocin. Oxytcin and prostaglandins work together to start thinning out the cervix. Once the cervix begins the thin, contractions are started. Each contraction is the body's natural attempt to lower the baby down closer to the vaginal opening for delivery. As the head gets lower, the cervix will thin out more and more. I once had a teacher say it's like squeezing your head through a thick turtle neck sweater. The neck is long and thick-but once your head starts to squeeze through it, it stretches to the size of your head and thins out all the threads of the sweater. Eventually, as the baby's head gets lower, the protective sac covering it will have so much pressure on the cervix that it'll break like a water balloon. This is what happens when people say \"My water just broke!\" Now there is no barrier for the baby to reach the outside, and labor should progress quicker now!",
"Hormonal signals if i remember correctly. I have birthed 2 children. My second didnt get the message though and i had to suffer through induction and c section because he was 12 days late. I'm not bitter though.",
"Labor is triggered by the Fetus due to “stress”. It releases a hormone called ACTH in non-human mammals, but in humans it appears that a placental (fetus tissue) hormone NF-kB plays a roll is starting labor. The “stress” is usually that the fetus has no more space to grow. Mother responds to these signals and prepares for delivery. The signals for preterm and miscarriage are varied. Due to the sensitive nature of the topics I won’t discuss Source: veterinarian"
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7d4103 | Why not grow brain-dead babies to harvest their organs? | Other | explainlikeimfive | {
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"It's viewed as unethical. People have concerns about even growing the organs themselves from stem cells and about stem cells research and usage in general. Growing whole bodies would even be an unnecessary overkill if you could grow just the needed organs. Growing stuff from stem cells is the way to go, but as I said, there's ethical issues people have with that.",
"Have you not seen the movie 'The Matrix'?",
"You'd have to keep these bodies alive for years until their organs were mature enough to use. This would be challenging medically, as well as horrifying to the parents."
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7d43kp | How come a few feet can make a difference in signal strength even when the signal is coming from miles away? | Technology | explainlikeimfive | {
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"The signal is reflecting off some items, blocked by others. And the reflections can collide with each other, creating complex patterns of interference over very short distances.",
"It's like the sun, it's millions of miles away but a few feet can mean the difference between glaring brightness and significant darkness. Much in the same way cell phone towers can have very small dark spots (like shadows)."
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7d46fw | Why do some objects melt when heated and others just burst into flames? | Chemistry | explainlikeimfive | {
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"Some objects are composed of complex combinations of molecules, where the bonds holding them together can potentially break down before you reach a melting point for everything involved. This break down with heat is (in part) what we observe with fire. Other forms of break down are possible. If you have a simple material, like a lump of a pure element, then you aren't going to encounter this before reaching the melting point."
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7d4l75 | Why do we feel elated when we help someone? | Biology | explainlikeimfive | {
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"Because as a socially- dependent animal, it is within our best interests, at base level instinct, to keep our (helpful) peers alive. So our body will reward the behaviour with a good feeling!",
"Because we're a social animal. Altruism is hardwired into humans. So when we help others we get happier. It is tied to the anterior insular cortex, a part deep in our brain that is used for empathy. From an evolutionary perspective it is a clever strategy since the more a species, a group or family helps each other the more likely they are to succeed.",
"There can be two ways of helping someone, let's talk about helping a stranger, called Altruism. We mammals have instincts to help those similar to us, and the 'similarity' can be really abstract and up to the mind to decide. Helping 'the enemy' in war time may feel altruistic, but your peers may disagree. Instinct and Society arn't always aligned, but when they are, our instincts can almost feel bigger than us. Getting an instinct-reward that feels bigger than yourself could definitely be called Elated. Helping friends is different, the tribal mammal aspect still kicks in, but half of the buzz is knowing the bond between you and the friend is stronger, and you can expect more support from them in future. Altruism could be called a 'cleaner' elation, but both are valid, and our instincts rarely reward us with these little rushes my mistake. We're ancient creatures afterall :D"
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7d4umg | What does the quote "He who fights with monsters should be careful lest he thereby become a monster. And if thou gaze long into an abyss, the abyss will also gaze into thee" mean? | Other | explainlikeimfive | {
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"Essentially what it warns against is that in fighting something bad, you should be careful not to take actions that make you as bad as the thing you are fighting. It can be really easy to justify extreme measures to yourself if you are fighting something you believe is evil, but sometimes you need to step back and look at what you are doing.",
"This quote tends to foster the idea that in becoming a 'monster hunter' one is exposed to darkness, and that exposure can allow darkness to spread in a 'hero' as a kind of infection. One other view is that the very act of 'creating a monster' in the mind allows one justify taking monstrous acts against all perceived monsters (making the Monster Hunter simply a Monster). > \"If only there were evil people somewhere insidiously committing evil deeds, and it were necessary only to separate them from the rest of us and destroy them. But the line dividing good and evil cuts through the heart of every human being. And who is willing to destroy a piece of his own heart?\" > > - Aleksandr Solzhenitsyn, The Gulag Archipelago",
"It means that the more time you spend around the darker sides of humanity and existence, the more it affects you. We humans adapt to our environment, and the more time we spend in an environment the more we adapt to it.",
"I believe that in \"He who fights with monsters\" they are referring to other people as the \"monsters\". History has shown that while fighting these people/monsters you are likely to dehumanize them. You no longer see them as people, but as monsters. Now that you no longer see them as people, you will do things you wouldn't have done before. Humane treatment is no longer a thing with these people, after all, they are not people, they are monsters. So the more you see them as monsters and not people, the more you turn into a monster yourself. \"And if thou gaze long into an abyss, the abyss will also gaze into thee\" This is along the same line. You spent too much time treating them as a monster, you became a monster. You spent too much time gazing into the abyss, the abyss gaze back at you. You turned over, you went to the dark side.",
"Terry Pratchett once wrote: \"Shoot the dictator and prevent the war? But the dictator is merely the tip of the whole festering boil of social pus from which dictators emerge; shoot him and there'll be another one along in a minute. Shoot him too? Why not shoot everyone and invade Poland?\"",
"It is Nietzsche. There is no ELI5 for Nietzsche. And this quote in particular comes from a section in Beyond Good and Evil that consists of aphorisms, so there isn't even a narrative context for it. The aphorisms around it deal with vanity and its effects on morality. As for a generally Nietzschean interpretation, the morality against which he struggles is primarily reactive, a negative reaction to something else. If he becomes nothing but his struggle against it, doesn't he risk having a merely negative, life- denying morality, as well? Nor can one simply embrace nihilism, as though an inhuman abyss were the truth about the world.",
"\"You either die a hero, or you live long enough to see yourself become a villian.\" That's not snark, they mean the same thing. You fight something enough and you become the thing you hate.",
"It means that often evil acts are committed in the name of good, and even if you prevail, you wind up just replacing one evil with another. The part about the abyss implies that it is hard to address evil without evil rubbing off on you.",
"We monkeys adapt to the challenges of life, and if we choose to pursue the darker parts of life, even if to conquer them, we will learn something about that darkness and accidentally use it in daily life. Hunting something is easier if you can think like the prey and predict what it will think. Learning to think like a criminal in order to catch them, has side effects ;P",
"Half of the agents I believe that took down silk road for example saw how much money you could bring in and started to sell themselves as well as taking down rivals using their training.",
"Explaining this bluntly isn't as easy. Essentially. If you fight with people who are bad you may become bad yourself from being there. And the abyss is your bad thoughts, thinking into them too much will take over your mind. Both match in that way, they can take over. You should be careful of bad people (monsters) who cant be good to you in anyway and thinking about negative thoughts too much (the abyss)",
"It means \"If you go to fight _____ by doing an act that _____ would do, make sure to not become _____\". One example would be Cromwell in England. He went and led a rebellion against absolutist James 1. He ended up an absolutist ruler himself. (Note: absolutist=dictator)",
"The thing about literature, and art in general, is that the meaning of it is what ever you taker away from it. Personally this quote means beware of the negative consequences that may come from rejecting those you disagree with, and fearing the worst in yourself. To elaborate: even if you don't like someone for whatever reason, you shouldn't be toxic towards that person. Doing so can cause you to become just as bad as the other guy. The second part feels like a metaphor for 'analysis paralysis'. If you believe something enough, it will become true for you; believing in your flaws are what makes them real. That being said, it could also take on an entirely different meaning given the context of the quote."
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7d54ps | How did we settle on twelve pitches to be the musical notes? What is the pattern behind 1,3,5 major chord/triad? | Other | explainlikeimfive | {
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"For thousands of years, people have discovered that certain pitches sound nice together - either at the same time, or when heard in a row. There's a really good physical reason behind that. Consider a musical A, which is traditionally exactly 440 Hz. The simplest possible note is a pure sine wave: URL_1 Note that each complete waveform in the graph above is 1/440 of a second. Every 1/440 of a second, it repeats. Your ear has stereocilia of different lengths. One particular length of cilia is just the right length that something that has a frequency of 440 Hz makes it vibrate perfectly, just like a swing has a natural frequency and trying to push it too fast or too slow doesn't work. The waveform doesn't have to be a sine wave! You can get other waveform shapes that still repeat every 1/440 of a second, and you hear that as the same pitch (but a different timbre, like from a different instrument): URL_0 Now to answer your question, look at the graph of 880 Hz. Note that while it repeats every 1/880 of a second, it's also true that it repeats every 1/440 of a second. URL_2 So, that cilia that vibrates well with the 440 Hz tone will also be stimulated by the 880 Hz tone. It's like if you push someone on a swing twice as often as the natural frequency, it will still work great - half of your pushes will be useless but the end effect will be lots of swinging energy. Today we call this an octave. A note with one frequency and another note with twice that frequency are one octave apart. Other intervals that sound good are also simple frequency ratios. For example, what we now call the perfect fifth - like playing a C and then a G, universally sounds pleasing. Every culture in the world that has music uses that interval. Mathematically it's just 3/2 times a frequency: so 660 Hz compared to 440 Hz, for example. We've discovered flutes 9,000 years old that play those notes. When you put other notes together that all sound good together, you get chords (if you play them together) and scales (if you play them in sequence). The 1,3,5 major chord you mentioned is just one example. In Western music, there are typically 7 notes in a scale. Most songs don't need any more than that. In fact, more than 90% of popular music songs from the past 60 years can be played with just 7 notes. (The keys are different, but it's the same 7 notes just in different keys.) So why do we have 12 notes? In the last few hundred years, it was discovered that by picking 12 notes **equally spaced mathematically** within each octave, nearly all of the notes from commonly used scales can be found among those 12 (not exactly, but mathematically close enough that our ears have a hard time hearing the difference). That way, with a single instrument, you can play all of the notes in all commonly used scales, but more importantly you can play them starting on any note. This allows you to play songs in any key, and also to modulate - change keys in the middle of a song. So 12 happens to work out really well. You could do 24, but many people wouldn't be able to hear the difference between some of the pitches. You could do 11 or 13 or some other number of equally spaced notes but then you wouldn't get many of the pitches that sound good in scales. You could pick pitches that aren't equally spaced in an octave but then you couldn't modulate - you couldn't play the same song starting on a different note."
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7d5nf4 | What Is The Difference Between A Regular Rocket Engine And A Vacuum Rocket Engine? | Technology | explainlikeimfive | {
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"A rocket engine optimized for vacuum is likely what you mean. It will have a different \"bell\" on the end to let the gas expand a bit more When in the atmosphere the air pushes back against the exhaust so it can't expand as much as in the vacuum so you need a different shaped exhaust nozzle to make it as efficient as possible. Vacuum has no air pushing back so it needs a different shape. You can optimize your rocket engine for atmospheric operation, vacuum operation, or a mix of both. Second stage engines generally only fire outside of the atmosphere so they're optimized for vacuum operation. First stage engines take the rocket from sea level to space so they compromise and make it pretty good at both sea level and in space A rocket engine will work fine at sea level or in space no matter where it was optimized for, it just might not be as efficient as possible"
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7d5nno | What causes dandruff & why are some people more susceptible to it than others? | Biology | explainlikeimfive | {
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"Causes : -Dry scalp -Not washing your hair often, not combing /brushing your hair often causes dandruff . New skin cells are forming on the scalp regularly while the old ones die . These dead skin cells then accumulate to form white flakes which is known as dandruff . -Another cause for dandruff is a condition (seborrheic dermatitis) in which the scalp is oily and itchy. It causes excess of oil production. The oil causes the dead skin cells to clump together and form dandruff. People with seborrhoeic dermatitis and those who have dry skin can be more susceptible to it then those who don't. But it can be avoided by cleaning /washing and combing the hair regularly as you will be getting rid of the of the dead skin cells before they have the time clump together to form dandruff"
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7d5o3f | How does currency exchange work exactly? | Where does the foreign money go after your exchange it? Do they ship it back to the country for the foreign exchange there? What about countries that don't have an established currency? | Economics | explainlikeimfive | {
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"text": [
"If countries don't have an established currency then they will use another countries currency. For example Ecuador uses US dollars. So they don't print their own currency, they use accept USD. Or even places like the British Virgin Islands. They are a Brittish overseas territory, but they use US Dollars. About 80% of their visitors are from the US, and 10% might come visit from Europe, so it would not make sense to use the pound. It would probably hurt tourism. If you exchange currency, at least on a small scale, they are not shipping it back to the country. Somebody is going to give 100 USD and request Canadian dollars, then the next person could have Canadian dollars and request USD, so hopefully it balances out in the long run. Of course that is a bit optimistic, and they do need to order more currency, or send currency back, so it does happen from time to time to keep their supply where they want it."
],
"score": [
3
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
7d5ym1 | Why is breast cancer more common in females than males; aren't hormones susceptible to change? | Biology | explainlikeimfive | {
"a_id": [
"dpv96lx"
],
"text": [
"They have larger breasts and therefore more physical matter that can have a mutation that turns to cancer. The hormones that seem to aid in the growth of breast cancer are in higher concentrations in females than males, so while they are subject to change on average they are much higher in women than in men."
],
"score": [
6
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
|
7d60sq | Why do certain drugs make your pupils change size? | Biology | explainlikeimfive | {
"a_id": [
"dpv9q74"
],
"text": [
"Pupil change is due to two muscle groups-- the iris sphincter (contraction) and the iris dilator (expansion). The sphincter response is linked to the parasympathetic nervous system, activated when we are in a relaxed state. The dilator response is tied to the sympathetic nervous system, involved in the fight-or-flight response. Drugs which activate these systems will cause their typical impact on pupil size. For example, when someone consumes MDMA they are activating their sympathetic nervous system, which triggers the iris dilator to widen the size of the pupil. In contrast, a drug like heroin, typically known to cause a relaxed state, will activate the parasympathetic nervous system, thereby triggering the iris sphincter to contract the pupil."
],
"score": [
19
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
|
7d64tb | How does this picture disappear? | [Here’s the post with the picture]( URL_0 ) Stare at a specific point for a couple seconds and you will see it disappears. Why? | Biology | explainlikeimfive | {
"a_id": [
"dpvav38"
],
"text": [
"Your brain stops telling you that it is there. Basically, your brain is concerned about *changes* to your environment. New or changing stimuli. Things that never change are - simply put - unimportant. It's the reason you never \"see\" your nose or \"feel\" your tongue in your mouth (unless you consciously concentrate on it). It's unimportant stimuli that doesn't ever change. So, when your brain is receiving a constant signal from some constant source, it eventually tunes it out. It's why you eventually stop smelling a bad smell (olfactory fatigue) and aren't constantly feeling the clothes touching your body (again, unless you focus on it). But, this is actually bad for sight. Vision is pretty important and purely motion-based sight would be a serious flaw. To compensate, your eyes are constantly moving. Since your eyes are constantly moving (very slightly) your brain sees the images coming in as being slightly different each time which is interpreted as movement, so you are always (mostly) aware of everything you are looking at. I say mostly because it's possible for large blotches of the same color to not register as moving even with the natural movement of your eyes. This is what is going on with this picture. Your brain really doesn't see it as moving, sees it as unimportant stimuli, so stops processing it."
],
"score": [
8
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
7d6c1c | How does intuition works? | Biology | explainlikeimfive | {
"a_id": [
"dpvi9fa"
],
"text": [
"It is kind of like how you can train a chicken to play tic-tac-toe. The chicken doesn't really understand what it is doing, but it does know that certain behaviors lead to a good outcome. It picks the right squares, it gets fed, happy chicken. Humans are the same way. Through trial and error, we learn a street with few pedestrians, abandoned vehicles, and boarded up windows probably means a rough neighborhood. We aren't doing a conscious socio-economy analysis, we are relying on a pattern we learned from past experience."
],
"score": [
3
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
|
7d6kgx | What's inside public commercial electric vehicle DC fast charger (50kW < ) that makes it cost $30k or more? | Technology | explainlikeimfive | {
"a_id": [
"dpvgevq"
],
"text": [
"A rectifier and DC power supply rated for 50+KW. That's a rather high power piece of kit, you can't make it with Radio Shack diodes. That device consumes twice the power needed to trip the mains breaker on your house."
],
"score": [
3
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
|
7d6l5l | Why do some people think it's beneficial to "alkalize" the body? | Other | explainlikeimfive | {
"a_id": [
"dpveodn",
"dpvg75x",
"dpvfqgx"
],
"text": [
"A sufficiently charismatic snake-oil salesman convinced them of it. Most people don't have much understanding of medicine, biology or science in general. If some huckster starts tossing around fancy sounding words, it's easy to convince them that he's right - especially if it's loosely connected to some actual facts.",
"The whole alkaline diet or alkaline water thing is pseudo-scientific mumbo jumbo. Your diet has exactly zero effect on the pH of your body, and you wouldn't want it to. Anything you eat must go through the blood stream before it can get to any other part of your body, so we need look no further than the pH of your blood to understand why diet does not affect the pH of the body. Haemoglobin binds to oxygen in the lungs and then carries it to other tissues to use. The absorption and release of oxygen by red blood cells is affected by pH. If it is too loo low (below 7.35 is called acidosis) your blood won't grab oxygen in the lungs and your tissues will die in minutes. If the pH is to high (above 7.45 is alkylosis) you absorb oxygen in the lungs, but the blood won't release it to your cells and the cells will also die in a few minutes. In order to keep the blood in the very narrow optimal pH range your hypothalmus essentially acts like a pH meter and tells your body to breathe deeper or faster when the pH is too low, which expels extra CO2, which in the blood is in the form of carbonic acid. If the pH is to high the hypothalmus slows your breathing and allows CO2 as carbonic acid to build up. These steps are taken within seconds of the pH being out of the optimal range. Any deviations caused by food you have consumed are corrected immediately. If they weren't, an orange would kill you in minutes.",
"I think a lot of people think being alkaline makes them feel better, when really it's just act of paying more attention to diet and potentially breathing techniques that do the trick. While there may not be a ton of scientific evidence supporting becoming alkaline there is plenty about diet and breathing/meditation."
],
"score": [
44,
27,
3
],
"text_urls": [
[],
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
7d6pd1 | How do plants make proteins? | Herbivores get their amino acids from the break down of plant proteins (cell walls, organelles, etc)... and build their own proteins from said amino acids. Then carnivores eat herbivores but break down muscles and other tissues down to amino acids and then make their own proteins. Is that correct? If so, then where do plants get their amino acids? How do they build proteins? Can you get amino acids from glucose? | Biology | explainlikeimfive | {
"a_id": [
"dpvi1i9"
],
"text": [
"You're not quite correct. Plants and animals derive many of their amino acids through amino acid synthesis using compounds derived from their diet (in the case of animals) and from soil nutrients and photosynthesis (in the case of plants). Not all organisms are capable of making all of the amino acids that they require, so they have to get those amino acids from their diet."
],
"score": [
4
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
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