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78j74u | What limits how quickly a battery can charge? Why can't you provide it with an excessive current to charge a phone battery faster? | Physics | explainlikeimfive | {
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"Batteries are chemical storage device. The transition between electrical energy and chemical state takes time. Extra energy is dissipated as heat. Too much heat and you compromise the cell container and/or the electrolyte. With lithium interacting with atmosphere, it catches fire and goes boom. You don't want that."
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78jgwi | if water can be made via exothermic reactions, why are we so diligent in finding water on Mars. Why not just make our own when we get there | Chemistry | explainlikeimfive | {
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"> if water can be made via exothermic reactions, why are we so diligent in finding water on Mars. Why not just make our own when we get there If you had a bunch of hydrogen and oxygen just sitting around then you could burn them to make water and energy. That would be an extremely effective way of both powering a base and supplying it with a source of fresh water. The problem with that plan is of course that hydrogen and oxygen aren't just laying around on Mars. We might carry it with us but the amount of water we would get out of the reaction would be precisely the same as the total mass of hydrogen and oxygen we brought, so the same problems of \"Why don't we just bring it with us?\" apply. Moving any amount of material to Mars is very difficult so if we can use things already on Mars that is much more efficient and practical.",
"Bringing things to Mars is very expensive. Somewhere around $45,000 per kilogram. Bringing a whole lot of water, or ingredients to make water, would be incredibly expensive."
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78jopg | Summers at the Poles vs at the Equator | We all know that winters are colder at the North and South poles, but are summers also hotter at these locations, since they have longer days? In places like Sweden, the Sun is in the sky for almost 22 hours a day during peak summer, so it should get hotter because of the constant Sun. Yet there's permanent ice at the North and South Poles, and satellite maps show areas of permafrost and snow even during the Summer, so obviously temperatures must be at least 0 degrees Celsius there. How does that happen with constant sunlight? Are the Sun's rays weaker due to the angle or something? | Physics | explainlikeimfive | {
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"> How does that happen with constant sunlight? Are the Sun's rays weaker due to the angle or something? Yes, the angle is the issue. Consider that there is a certain amount of energy per area of exposure to sunlight. Imagine a sheet of paper which is flat vs edge on to you. The more angled the sheet of paper is toward being edge on the less area exposed to the light and the less overall energy is being absorbed. Even though the poles get nearly constant sunlight they are still getting less energy input overall than the equator."
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78k561 | Why do we feel sleepy in warm temperature rather than cold temperature ? | Biology | explainlikeimfive | {
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"I learned at least one of the reasons for this from a professor last semester. He's a kineticist (that's a field of chemistry) and very into endurance running -- and he told us just exactly why the perfect running temperature (high 60s to low 70s) is what it is: Pyruvate kinase Essentially, the heat outside actually interferes with the body's ability to make ATP, the energy molecule, out of the food we digest. This happens because pyruvate kinase, a crucial enzyme in ATP synthesis, is concerted mostly into a biologically inactive conformer at around 85 degrees F. This conformer is present in some portion at 70 degrees, but it's mostly the active form that dominates. After about 85 or so, you have a 60/40 ratio of the inactive to active forms. TL;DR heat slows down your metabolism and you run out of energy.",
"I feel sleepy in warm weather but can’t sleep in warm weather. Sleep like a baby in cold weather...as-long as I’m under a warm blanket...I’m defective"
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78k7iv | Why is water so enjoyable even though it has no taste? [Other] | Biology | explainlikeimfive | {
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"All water has a taste. Some waters taste good, and others like Dasani and Aquafina taste like plastic. Tap waters taste very different from city to city, and filtered water tastes different from reverse-osmosis water",
"Some water has taste, actually most water. Even distilled water had a sterile flavor. I cant drink arrowhead, tastes like dirt. But back to your question, I have to imagine part of it is that your brain knows your body needs it. Like eating anything when you're starving. And the pleasure involved in quenching your thirst. Dang, now I'm thirsty"
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78kc0v | How do they track baseballs during a game and turn it into a visualization for the audience? | Technology | explainlikeimfive | {
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"There are three cameras set up at known locations in the ball park and the distances and angles between them, the plate and pitchers mound are known precisely. Each camera records the ball as it moves from the pitcher toward the plate and the location in each camera is combined in order to calculate the exact position, speed and even rotation of the ball at each instant in time. A different set of three+ cameras record the ball once it is hit by the batter and do the same calculation for distance, altitude, angle, etc. Source: [Pitchf/x]( URL_1 ) was the system used by MLB through last year, now [Trackman]( URL_0 ) does it, but pretty much the same way."
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78kdnu | Why do people hallucinate when they get very tired? | I was watching an interview with [Courtney Dauwalter]( URL_0 ) after she completed a 240-mile foot race and she mentioned hallucinating during the race. Personally, I remember (several years ago) hallucinating in army basic training during a very long ruck march. I also have had some mild hallucinations after not sleeping for extended periods of time. Why do our minds sea and hear things that aren't there during time of extreme physical exertion? | Biology | explainlikeimfive | {
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"Why we need sleep and why we have side effects such as hallucinations from sleep deprivation is still poorly understood, but here's a common explanation dumbed down to a 5 year old level. Your brain is constantly working to fill in gaps and blanks. This is a normal process and you brain constantly does it. Your brain doesn't like missing visual gaps, such as in your peripheral vision so it invents what it thinks is really there. Most of the time it's accurate. Being sleep deprived causes timing issues. So what happens is that your brain tries to fill in these gaps with what you think you're seeing, and process these missing gaps with imagery you are familiar with, before your brain finishes processing other sensory input. This leads to hallucinations and seeing things that arent really there.",
"We are basically hallucinating all the time. Our vision is highly processed. What our eyes see is very different than what our brains perceive. Gaps get filled in, colors get adjusted, depth gets added, and a bunch of other little things that turn colored blurs into reality. When were are very tired or under the influence of drugs, our brains are less able to do this correct, and things we see get misinterpreted."
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78khm8 | How do you get clean from a bath when you're basically just laying in a small pool of your own stink? | Biology | explainlikeimfive | {
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"dilution. all that stink was on your skin. if you used scrubbed with soap or some other surfactant, that stink and dead skin is now in the volume of bath water and a little bit on your skin. if you don't rinse off after a bath, that little bit stays on your skin. so...rinse off. or just take a shower to begin with.",
"A quick Google tells me that the surface area of a human is about 2m^2 if you then say that your \"filth\" is an average of 1mm thick, which is a ridiculously high estimate then you have 2 liters of filth on you on you. A bath has a capacity of a couple of hundred of liters so if the liquids mix perfectly you are left with 1% of you original “filth”",
"The best way to clean yourself is to shower to get rid of most of the stink, bath so the stink that's left can soak and then shower again to rinse off the remaining stink. this is my preferred method of relaxing in a bath."
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78khw5 | What does "bulking" (for bodybuilders) do to your body in a biological sense? | Biology | explainlikeimfive | {
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"You're eating to give your body an abundance of the materials it needs to make muscle. You will eat more calories than you burn (so you aren't using up stored energy) and you'll eat a surplus of proteins (so you have enough amino acids which are the building blocks of proteins). You do this so when you work out your body is in the ideal situation for building more muscle. This is in contrast to people who want to lose weight and work out in order to burn more calories than they consume. This forces the body to use up what you already have and thus lose weight."
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78kzw8 | How can someone be absolutely sure that a number is irrational, not a fraction with obscenely massive numerator & denominator? | Like pi or e. Could they actually be rational numbers with an extremely large denominators (something as large as Graham's number)? | Mathematics | explainlikeimfive | {
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"The definition of an irational number is that it CAN NOT be written as, p/q, where p, q are integers and q != 0. It is possible to prove this for numbers. For example we can use a proof by contradiction to proove that sqrt(2) is irrational. Proof that sqrt(2) is irrational: Assume that sqrt(2) is rational. By definition of rational numbers we can right a/b = sqrt(2). Further assume that a/b is reduced, so that a and b do not share any common factors. (If they do then simplify the fraction and you have your new a and b). Then: a/b = sqrt(2) (a/b)^2 = sqrt(2)^2 a^(2)/b^(2) = 2 a^(2) = 2b^(2) This means a^2 is an even integer, which is only possible if a itself is even, and a = 2k, for some integer k. Then: a^(2) = 2b^(2) (2k)^(2) = 2b^(2) 4k^(2) = 2b^(2) 2k^2 = b^2 This means b^2 is even, which is only possible if b itself is even. But if both a and b are even then they share 2 as a common factor. This is a contradiction of our original assumption. Therefore sqrt(2) can't be rational. As the other person says the proof for the irrationality of pi and e are not as simple.",
"There is no general proof that a given number is irrational. Some (sqrt(2)) are easy to prove, others aren't. Pi wasn't proven irrational until rather recently considering how long we've known of the number. A common method for proving irrationality is by contradiction: assume the number is rational, and then show how that leads to an impossible situation.",
"In most sciences, it's not possible to show that something is true, only that it is extremely unlikely to be false. If you have a theory that explains a phenomenon and makes accurate predictions about it, then that theory is accepted. But another theory could come along that explains the phenomenon better and makes better predictions, in which case the old theory is rejected. In that sense, a theory is not \"true\", just accepted. In mathematics, however, it is possible to prove something as absolutely true or absolutely false. When mathematicians state that pi is irrational, they don't mean they haven't been able to find two integers whose ratio is equal to pi, and that as a result pi is very likely to be irrational; they mean they have *proved* that there are no such integers."
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78lmik | Why do most medicines come in a box that can fit more pills, but only feature a single slim sheet? | Biology | explainlikeimfive | {
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"The same equipment used to package other medications is used to make that allergy medication package, and those others may include more pills and differently sized pills. The box needs to remain about the same size to fit on the shelves as intended, show the desired advertising, etc., and the medication within it shouldn't rattle around too much so the sheet size needs to be appropriate for the box. But to hit a price point or provide a reasonable amount of medication they don't want to just cram as many pills in as they possibly can. The result is a sheet with gaps."
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78lnwg | Why are so many diseases that were harmless to animals so dangerous when they first moved to people? | Biology | explainlikeimfive | {
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"There are a many answers to this, and it varies by animal and disease-causing organism. I'll give a few basic ones, from which everything is derived: 1. In many cases it can hurt them, but not as bad if at all. The organism relies on the animal to survive, and has evolved over time to not totally kill them. The animal has also adapted to the bacteria via early exposure. Mammals, for example, will have received antibodies from the mother which will help until the baby's immune system kicks in. 2. Isolation. The organism may only survive on the animal in a specific place, for example the skin. Along with #1, if the organism tries spreading somewhere else, the animal's immune system will kill it. This means it will happily carry a dangerous organism and let it survive, because it is killed or isolated from areas where it could cause harm When a human is exposed to one of these, our immune system is entirely unprepared. The organism may act in a way we're especially vulnerable to (compared to the host), and we have no existing antibodies for it. By the time the body can mount an adequate immune response, it's possible that the organism has spread wildly. This also happens between human populations. Europeans once struggled with small-pox, but through medicine and certain exposures became immune. We continued to co-exist with animals that carried small-pox and perhaps even had it on our skin. When Europeans came to America, small-pox wreaked havoc on native populations.",
"Confirmation bias. The ones that pose a threat to humans are the only ones that make the news. There might be a hundred diseases are serious in an animals and mild in humans that you would never hear about."
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78luwu | How does rotation stabilize a moving object? | The examples that come to mind are a bullet leaving a gun, or how a baseball pitched with minimal spin tends to have “movement” on its flight to the catcher. | Physics | explainlikeimfive | {
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"By rotating the object kinetic energy is stored in the rotation making it behave like a gyroscope. Conservation of momentum then makes it much more difficult to change the axis of rotation because you are in essence changing the direction of its movement. To understand this imagine a vacuum with an object traveling in a direction. If you wanted to cause that object to travel in a direction 90 degrees from its current path you are not only going to need to add thrust in that new direction but you are ultimately going to need to input enough energy equivalent to stopping the object's original movement. Otherwise it will always continue to move in the direction of its original path even if it is also moving in the new direction at some speed, resulting in it traveling at an angle. Now consider our rotating object, or more precisely a piece of material on the edge of the object. If we imagine what it would do if not attached to the object it would clearly want to zip off in a straight line in the direction of rotation. Now imagine tipping the projectile's axis of rotation 90 degrees; the same chunk of material now would want to shoot off at a direction 90 degrees from its original trajectory, not at some combined angle. Obviously its momentum in the original direction must have been negated in the course of rotating the projectile! (There are some locations on the object where the directions don't change, in which case just imagine another chunk a quarter of the way around the object.) That necessary input of energy in order to redirect the axis of rotation of the spinning object is what keeps the gyroscope stable. In the case of a spinning bullet it keeps the nose of the bullet pointed in the direction of travel, preventing it from tipping out of line resulting in uneven drag which would pull it off course."
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78m41g | Why does iron rust faster in the presence of saltwater? | Chemistry | explainlikeimfive | {
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"Ahoy, matey! Yer not alone in askin', and kind strangers have explained: 1. [ELI5: why does adding salt to water cause metals submerged in the water to rust more quickly? ]( URL_2 ) 1. [ELI5: why does iron dissolve faster in salt water than water? ]( URL_1 ) 1. [ELI5: Why does salt water increase rate of corrosion? ]( URL_0 )",
"Rust is iron oxide, the result of oxygen interacting with iron in the presence of water. When this happens, the iron oxide forms a barrier to the rest of the iron behind it, so other factors, like wind erosion, need to remove the rust to get to the iron underneath, to then change that to rust. With salt water, there are ions present, keeping any barrier from forming, and the iron and oxygen can continue to change to rust unimpeded."
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78mvq7 | How are property lines decided and recorded for residential purchases? | Other | explainlikeimfive | {
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"Property lines are drawn when the area is first developed. If the area was first developed in modern times, it would have been split up into individual parcels and each parcel's lines would have been drawn quite precisely. If it was first developed a long time ago, there may be some uncertainty in the lines and records of usage can be necessary to determine who owns a particular piece of land. The details of how they're recorded vary depending on the jurisdiction, but there's usually a governmental office that is in charge of recording property lines. In England and Wales, for instance, it's HM Land Registry."
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78n2up | - Why is it that we can hold our bladders for hours, but as we get closer to a toilet it becomes uncontrollable? | Biology | explainlikeimfive | {
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"I think it's similar to why they always say you should only use your bed for sleeping in. That way as soon as you get into bed your body will start to shut down. It's all about association.",
"My bladder is fairly realistic but my bowels are very optimistic about how quickly I can get to a toilet. Rushing home to get to the pan and just putting the key in the front door seems to trigger the \"bombs away\" command.",
"I am not a scientest but I'm pretty sure it has to do with being trained that that is where we pee. Subconsciously you know that you can't per in the car so it's easier to hold putting a proverbial clothespin on your bladder, but once you know that you are within spitting distance of the toilet it takes that clothespin off.",
"Definitely psychological association with the toilet being where we can actually relieve ourselves. I remember as a child I would wet the bed when I dreamed about being in a bathroom stall. So glad that doesn't happen to me anymore (knock on wood)",
"As a kid I used to hold my breath while we were driving in a tunnel, no matter the reasonable length it was always the last 5 seconds that was the real challenge. Would like an explanation to this too."
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78n9sp | What, exactly, is Petro-Yuan and how will it affect the US dollar? | Economics | explainlikeimfive | {
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"It creates an automatic demand for dollars that keeps the value of the currency high. We could produce no exports of any kind, and the money would stay valuable because everyone needs to buy oil, and oil only sells for dollars. It's pretty unlikely that China will make that move in the near future, since devaluing our currency would basically gut their economy...Yuan being cheap compared to dollars is what drives the trade gap between our countries, and they have worked hard to keep that state of affairs going.",
"Trading oil in US currency does almost nothing to bolster the US dollar's value. It's a myth. If the yuan takes over as the currency of choice, it would mean little beyond one fact, the Chinese yuan is a bigger reserve currency than the US dollar for oil. There are about 6-7 currencies that are considered solid currencies. The yuan, while relatively new, doesn't really change the market all that much.",
"i am not an economist nor an oil tycoon but people have been sabre-rattling for decades over how china will finally dethrone the US as an economic and industrial powerhouse and the reality of the situation is that we've found ourselves in a co-dependent relationship and i highly doubt anything will change the status quo. this seems like yet another reason that china will totally shake things up economically, for real this time! china's entire mode of operation is claiming things are better than they they are to save appearances to the point where it is not only government policy but government policy they have a reputation for, and western outlets like to take the sweeping grand statements made by the chinese government-sponsored media as fact when they should under no circumstances ever be."
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78nghg | How deodorant works and why it "stops working" after a bit | Chemistry | explainlikeimfive | {
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"deodorant kills the bacteria that grow in your armpits so they don't make the smell you associate with body odor, and usually also smells nice antiperspirant blocks your sweat glands so that they don't extrude the sweat that the bacteria feed on to make body odor in both cases they stop working when the active chemical isn't present in a high enough concentration to keep working",
"Not so fun fact about antiperspirant: it contains aluminum which discolors your shirts. My advice is to stick to a regular deodorant.",
"Not sure if it's been asked already but what about people who sweat like momma June on her front porch in the middle of a hot Mississippi summer no matter what they use? Antiperspirant, deodorant, I sweat through it all.",
"My question is that why haven't all of the different body odors been classified and mapped? It seems as if people are embarrassed about it."
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78niim | If the UK economy is improving, why propose raising interest rates? | Economics | explainlikeimfive | {
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"When an economy is going full blast there are many opportunities for investment. There are more possibilities than there is money available. Money is rationed by charging interest for its use. If a project has good prospects for a good return then it will be worthwhile investing the money and paying a higher interest rate. The world economy has been in a strange state for years. Money has been readily available but there was a lack of good investment opportunities. So interest rates have been historically low."
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78nlst | Why do farts smell differently from time to time, if all of them is just methane? | Biology | explainlikeimfive | {
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"Methane is an odorless gas. What you smell are impurities, which are often sulfur compounds, which can vary with what you eat.",
"It isn't just methane. It is also the decomposition of what you were eating. Some foods notoriously have bad breakdowns (veggies especially) and others have very stable and \"smell-less\" byproducts (I think potatoes and other starchy foods are in this category). Essentially it depends on what you eat."
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78nv7k | when someone dies, what happens to their debt? Does it go to their executor to be paid off with money from selling their estate? What happens if there is more debt than money in the estate? | Economics | explainlikeimfive | {
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"When someone dies, all of their assets and debts become part of their estate. The executor of the estate then pays off all of the debts using the estate assets (selling assets if/as required). Once all of the debts are paid, the remaining assets are then given to the beneficiaries of the estate (either through the will or applicable laws). If debts are greater than assets, the debts are paid to the extent possible and then are discharged (e.g. negated) once the assets run out.",
"> Does it go to their executor to be paid off with money from selling their estate? That is exactly what happens. Debt comes out of the estate, and anything left goes to the heirs. If the estate is exhausted, the creditors are out of luck. The heirs are not responsible for the debt unless they jointly owned property with the deceased. In that case, only the shared property could be liquidated.",
"I've dealt with this in the past so I can offer some insight. This varies depending on the jurisdiction you're in. In general here's how it works in the US. When someone dies their debt and assets become part of their estate. The estate is its own sort of legal entity. The executor is the person in charge of making sure everything the estate is responsible for happens, and that the dead person's will is carried out. An estate is responsible for settling any debts it owes before the beneficiaries inherit anything. How exactly that works isn't specified, and can generally be negotiated. For example if the dead person owned a house with a mortgage, the beneficiaries could sell the house, pay off the mortgage, and keep the difference. Or they could keep the house and take over the mortgage payments themselves. If an estate has more debt than assets, it's generally handled like a bankruptcy. There would be a series of court hearings to determine who gets paid and how much. The beneficiaries would not, in general, be responsible for any debts the dead person had, unless they were cosigners on those debts."
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78nzxx | Does the thickness of your blood actually change based on your environment? If so, how and why? | As in, people in hot climates are said to develop thin blood, and vice versa. | Biology | explainlikeimfive | {
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"Yes, constantly, but not much. When you sweat, you loose water from your blood, so as you get dehydrated your blood thickens somewhat. When speaking of people in hot climates developing 'thin blood', that's more a matter of their bodies being habituated to higher or lower required levels of energy for temperature maintenance. If you live in the temperate zone, you probably 'feel' a chilly morning much more in early fall than in late spring. Your body slowly adapts to 'usual' conditions."
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78o7l6 | How much effect does Central Park have on New York City's air quality? | Other | explainlikeimfive | {
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"Ever spit into the ocean? It's about that much effect.",
"There are two separate possible alternatives: * Central park is replaced with a giant void that has no effect on the outside world * Central park is developed as densely as the surrounding area. The park itself has very little effect directly. The trees and grass don't offset much of anything considering there's 30 million people surrounding it, while wind and rain throughout the region move massive amounts of pollution. However, if you put up buildings and roads there, it would increase the population, the cars, the wastewater, the need for indoor gyms and other recreation... all of which would add more pollution. With that said, America's cars run cleaner than ever, and there's very little industry in Manhattan. It's also by the ocean so there's more wind than other cities, and so either way, it wouldn't make a huge difference."
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78oghy | If the temperature of something is really just the kinetic energy of its particles, how can a such a strong wind be so icy cold? | Physics | explainlikeimfive | {
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"The kinetic theory of temperature does not include macroscopic movement such as wind, only the movement in a non-moving reference frame. Imagine a volume of air in a container moving along with the wind, only the kinetic energy with respect to the moving container counts, not the overall movement of the air-filled container itself. Otherwise the temperature would be entirely dependent on the reference frame as the gas could be considered low temperature with respect to the ground, but very hot relative to the sun, with a velocity of 10m/s relative to the ground but 30000m/s relative to the sun."
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78ozyg | Is leaving a cup of water overnight a bad idea? | I often use the same cup for a week or so and have it sit overnight most nights in case I get thirsty. Sometimes in the morning the last bit of it has a vaguely "skunky" smell/taste. Is it a bad idea to drink this? | Biology | explainlikeimfive | {
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"If it smells: don't drink it. Literally this is what the human sense of taste evolved to let you avoid. However generally leaving a cup of water overnight in a clean glass isn't a problem. I think your issue is you don't wash your cup often enough.",
"Plain water doesn't \"go bad,\" but water with a tiny bit of your saliva in it may grow some bacteria over time. Also, a little dust may land in it. Overnight is no problem if you empty and refill it daily.",
"I don’t go to sleep without a glass of water out. After awhile the carbon dioxide in the air mixes, and it will change the taste, but overall not unsafe to drink.",
"Nalgene bottle bro. It'll cost you like $12. Buy two so you can have one to use while the other is in the dishwasher. I seriously never go anywhere without mine."
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78p1w8 | How do commercials work? | How is the order decided? When a company owns a lot of channels, how is it decided which channels will show the commercial and which ones won't? Why do some national stations show the same 5 commercials all day? | Technology | explainlikeimfive | {
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"text": [
"The advertiser specifies what channels and what shows they want their ad on, and how many times. They can choose a single show, or a category of shows based on type or based on audience statistics."
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78p4pn | How does the Federal Reserve figure out how much money to print/mint each year? | Economics | explainlikeimfive | {
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"Minor quibble, for clarification only: the Fed doesn't produce coinage or currency. The US Mint and Bureau of Engraving and Printing, respectively, do that. But the Fed is the only entity that can place orders for either, so really, the question is still well-put. To answer, the Fed estimates the need for new coinage/currency the same way a business estimates the demand for its products: it generates forecasts for *this* year based on actual figures from *previous* years. Throw in a few tweaks, here and there, for specific, identifiable events that are likely to throw things off a bit (e.g., the introduction of a new bill, etc.), and Bob's your uncle.",
"The Federal Reserve Bank runs a program called FedCash. They accept sorted currency and fulfill orders. It's relatively standard supply-chain management. They know how much was ordered each month in the past, the lead time to get more from the BEP, and how much they have on hand. While they occasionally make mistakes and run low, it's not normally a problem.",
"I am going to assume you don't know what you were actually asking (most people don't) and answer the question I think you asked. How does the Federal Reserve figure out how much Quantitative Easing and other tools to control the interest rate to use each year? People who criticize the Fed's policies are generally talking about this and pejoratively call it money printing. Also the question now has several ELI5 embedded into it. 1. What is Quantitative Easing? QE is a program where the fed would buy loans from banks in exchange for increasing the amount of reserves the seller had at the Fed (basically let the banks loan more). 2. What other tools does the Fed have? The main tool is actually buying and selling Federal debt, already purchased by others, in exchange for reserves. 3. What is the interest rate the Fed controls and why is it important? The Fed controls something called the Fed Funds rate which is important for determining the rate at which banks will loan each other money overnight so they can be legally operated. Banks are required to have at least a certain percentage of their deposits in cash (10%) so these loan make sure they are always above that limit. 4. How does the Fed know how much of these tools to use? They want to maintain full employment and stable prices (low inflation) they look to see if unemployment is rising too fast or just generally very high. If it is they will lower rates. If inflation is too high they will raise rates to get it under control.",
"When it comes to actual, physical currency - Bills and Coins - whatever member banks of the Federal Reserve ask for, the Fed will essentially give them. In a modern economy, from a broad monetary perspective, physical currency is basically meaningless. The overwhelming majority of the money supply exists purely in electronic form. So when the Fed is \"printing money,\" really what they're doing is buying assets (usually bonds, but in extreme circumstances other assets) from banks, and giving them electronic currency in exchange. This buying and selling of bonds is called Open Market Operations, and it's the primary way in which the Fed controls inflation. In order to determine how many bonds to buy (or sell) the Fed targets an interest rate. If the Fed sells a lot of bonds, the supply of bonds will increase, and the price of them will drop. This means that in order for the Federal government to issue new bonds, they have to have a higher return. By raising the rate of return on new Bonds, the Fed also raises the interest rate on most other savings instruments as well. US treasury bonds are considered to be risk free (or as risk free as an investment can get), so in order to compete with the increased return, other savings and investments need to promise a higher return as well. This slows down consumption (as savings becomes more attractive by comparison), this drives down employment, which then drives down inflation. So to answer your question, the Fed figures out how much money to \"print\" each year by looking at unemployment and inflation. It then performs open market operations in order to effect interest rates in order to hit it's unemployment and inflation targets.",
"OP, can you clarify whether you mean the physical printing/minting of currency or the creation of money itself? They are different things. Currency is not the same as money. The answers you are getting are making an assumption one way or another, but they are not going to flesh out the true answer unless they know what you are asking. Currency is a method of transferring wealth, money is a method of quantifying it. Some money is currency but not all currency is money."
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78pbf5 | 1/X^n = X^-n | Mathematics | explainlikeimfive | {
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"The relationship between different powers is as follows: You can get from X^n to X^(n-1) by dividing the former by X. That is, X^n divided by X equals X^(n-1) Given that X^1 equals X, we can use the above rule to find X^0. X^0 is X^1 divided by X. X^1 equals X so X^0 is X divided by X, or 1. Now, we can use the above rule to find X^(-1). X^(-1) is X^0 divided by X. X^0 equals 1 so X^(-1) is 1 divided by X or 1/X. Since X^1 equals X, we can substitute that back in and get 1/X^1 And you can keep going. You'll find that, through the same methods, X^(-2) equals 1/X^2 , X^(-3) equals 1/X^3 and so on.",
"If you have (3×3×3)×(3×3) then that's 3^3 × 3^(2). However, since the ordering doesn't matter in a string of multiplications we could rewrite the initial statement as 3×3×3×3×3 which is just 3^(5). In other words, X^a × X^b = X^(a+b). Continuing this, (3×3×3)/(3×3) is just 3^(1), because two of the threes cancel out of the top and the bottom of the fraction. We can rewrite this as X^a / X^b = X^(a-b). Next we look at the case of a=b. What's (3×3)/(3×3)? That's just one, since the top and bottom are equal. By applying the previous rule we see that 3^(2)/3^(2) = 3^(2-2) = 3^(0), but we can also see that 3^(2)/3^(2) = 1. The rule this shows is that X^0 = 1 (provided that X is not zero). Finally, we take 3^(0)/3^(2). We know that 3^0 is 1 by the previous rule, so this is the same as 1/3^(2). We can also rewrite this statement as 3^(0-2) which is just 3^(-2). Written generally we have 1/X^n = X^(-n)."
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78plnq | Do has giants have a surface? Or is it just a giant ball of gas? | Other | explainlikeimfive | {
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"text": [
"Essentially, we don’t know for certain. It is _believed_ that they have solid cores, but that is (albeit well-evidenced) conjecture. One theory suggested that Jupiter has a diamond core. The sheer mass of these planets suggests that the core _should_ be solid, but at the moment we don’t know for sure."
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78pnzo | Why do they say that the kitchen sink has more bacteria than your toilet? | Chemistry | explainlikeimfive | {
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"Because [\"The meat industry sued the federal government, winning the right to sell food known to be contaminated with food-poisoning bacteria.\"]( URL_1 ) edit: Why the down vote? Studies find more fecal bacteria in kitchens than in bathrooms precisely because our retail meat contains so much fecal bacteria: [Consumer reports]( URL_3 ):\"All 458 pounds of beef we examined contained bacteria that signified fecal contamination (enterococcus and/or nontoxin-producing E. coli).\" [J Appl Microbiol. 1998 Nov;85(5):819-28]( URL_0 ). Reduction of faecal coliform, coliform and heterotrophic plate count bacteria in the household kitchen and bathroom by disinfection with hypochlorite cleaners. [Appl Environ Microbiol. 2017 Oct 13. pii: AEM.01902-17. doi: 10.1128/AEM.01902-17]( URL_2 ) [Epub ahead of print] Prevalence and Antimicrobial Resistance of Enterococci Isolated from Retail Meats in the United States, 2002-2014: \"Enterococci, including Enterococcus faecalis and E. faecium, are present in the gut of food-producing animals and are used as a measure of fecal contamination of meat. We used the large, consistent sampling methods of NARMS to assess the prevalence of Enterococcus strains isolated from retail meats, finding over 90% of meats to be contaminated with enterococci.\"",
"Unless you're letting your waste sit in your toilet for a long time without flushing, your toilet only has clean, drinkable water in it 99% of the time. Your kitchen sink, on the other hand, often will have food particles and the like, which is great food for all kinds of nasties. Of course, if you regularly clean both, you will almost never have to worry about either of them being of much harm to you.",
"Like I said, at first I only linked to the nutrition facts video that, had you watched it or looked at the transcript, you'd see specifically cites bathroom vs kitchen bacterial comparison study. The rest is background I gave after being downvoted. Look at the title of study 2. It's talking about fecal. I even linked the full text. It's the original source of the statistic about toilets versus sinks, and it's focused on bacteria in meat. No, 2/3 are not addressing the specific question, but I doubt most people realize how much fecal bacteria is on their meat, and it certainly supports why kitchen sinks are more contaminated than toilets. The sources link under the nutritional facts video has several studies about how problematic this bacteria is and why \"just cook it well and clean up afterwards\" is not working well."
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"https://www.ncbi.nlm.nih.gov/pubmed/29030448",
"https://www.consumerreports.org/cro/food/how-safe-is-your-ground-beef"
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78pxjm | Confidence Intervals? What are they and what do they do? | Mathematics | explainlikeimfive | {
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"When we talk about statistics, we have to distinguish between studying a sample and studying a population. We very rarely can test the population as a whole, so we tend to take samples of the population to run our calculations on. Now, a sample is only part of the population, so the confidence interval lets us approximate a population parameter if we're only given a sample statistic Let's say that we want to know the average height of every adult male in the united states. We take a sample of 100 people from each state for some reason, and find that the average height of the sample is 5'9\", with a standard deviation of 3\" Then, if we know that the sample came from the population, we can make the assumption that the actual mean height of the population of adult males in the United States is within some range of 5'9\" Specifically, we can say with some degree of confidence that the population mean is somewhere between 69-3z and 69+3z inches, where z is a value that is determined by the degree of confidence you want. So let's say you want to be 95% confident, so mostly certain, but with just a small degree of uncertainty. Then z=1.95, so we can say that the average population height is somewhere between 69-3(1.95) and 69+3(1.95) inches tall"
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78q8aa | Why is it so hard for game developers to scale UI's across multiply screen resolutions? | All other game elements get scaled just fine (ex. going from 1080p to 4k). You're character and the environment stay the same size on the screen. However, the UI (HUD, mouse cursor, option menus, etc) get shrunk down to 1/4 size. Sometimes, there is a UI scaler included in the options, but most of the time, it seems to cap at 140%. | Technology | explainlikeimfive | {
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"Because it requires more code and therefore time and money to make a 'good' UI. It's comparatively much simpler to fix everything in place or scale it by a fixed amount for different resolutions. If you're asking why they never include a stronger UI scaler it's that there's just not much demand for it. I'm sure you'd love it but the vast, vast bulk of their customers aren't going to be using such a large screen that the UI scale becomes a problem.",
"I've had to deal with this problem in hobby projects. There are really a few reasons for this: 1) As soon as you change aspect ratio (say, between a 16:9 and 16:10 screen), your proportions all change. My \"put this thing 10% from the left edge of screen\" may look great at 16:9 but it may bump into another UI object in 16:10. Same problem with font size - how large should a font be for each resolution? Without testing them individually, I need to just come up with a math formula and hope for the best. This just plain-old isn't as good as testing every combination one at a time and with different aspect ratios changing font sizes is just a nightmare of trouble. 2) There is a bit of tediousness and laziness to it. Getting everything to look right in every possible resolution is EXTREMELY time-consuming and probably the least-interesting thing you could possibly be working on. Nobody wants to do it, it's expensive when you're paying a team to make a TON of different art assets in different aspect ratios and paying a DIFFERENT team to test all this and get you all the numbers you need for every bloody piece of UI in the entire game. It's not fun, it's extremely time-consuming and...Where do you draw the line? How do I decide what resolutions to just not support anymore? Should I just ignore anything below 1366 x 768? Should I even bother trying to support THAT resolution when it's SO much lower than 1080p? But so many entry-level laptops use it, so I should probably test for it, right? Or should I? Should I bother fully testing 1920x1200? It's not common but it is out there. It's even worse with phones when practically every phone ever released has a different resolution/aspect ratio."
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78q928 | What happen(s/ed) to all of those crazy "future technologies" we hear about, but suddenly drop off the face of the earth? | Technology | explainlikeimfive | {
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"text": [
"All of the above. Some technologies work well in the lab, but can't scale to industrial applications. Some are just too expensive to pursue at this time. Some are bought and sat on by companies until they can switch their business models to take advantage of it."
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78qj56 | Falsifiable hypotheses | I'm having trouble wrapping my head around falsifiabiltiy as it relates to scientific validity. Is it simply the ability to prove a hypothesis wrong? Am I overthinking this? | Other | explainlikeimfive | {
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"I'll just quote Carl Sagan, from [The Demon Haunted World]( URL_0 ): > \"A fire-breathing dragon lives in my garage\" > Suppose (I'm following a group therapy approach by the psychologist Richard Franklin) I seriously make such an assertion to you. Surely you'd want to check it out, see for yourself. There have been innumerable stories of dragons over the centuries, but no real evidence. What an opportunity! > \"Show me,\" you say. I lead you to my garage. You look inside and see a ladder, empty paint cans, an old tricycle--but no dragon. > \"Where's the dragon?\" you ask. > \"Oh, she's right here,\" I reply, waving vaguely. \"I neglected to mention that she's an invisible dragon.\" > You propose spreading flour on the floor of the garage to capture the dragon's footprints. > \"Good idea,\" I say, \"but this dragon floats in the air.\" > Then you'll use an infrared sensor to detect the invisible fire. > \"Good idea, but the invisible fire is also heatless.\" > You'll spray-paint the dragon and make her visible. > \"Good idea, but she's an incorporeal dragon and the paint won't stick.\" > And so on. I counter every physical test you propose with a special explanation of why it won't work. > Now, what's the difference between an invisible, incorporeal, floating dragon who spits heatless fire and no dragon at all? If there's no way to disprove my contention, no conceivable experiment that would count against it, what does it mean to say that my dragon exists? Your inability to invalidate my hypothesis is not at all the same thing as proving it true. Claims that cannot be tested, assertions immune to disproof are veridically worthless, whatever value they may have in inspiring us or in exciting our sense of wonder. What I'm asking you to do comes down to believing, in the absence of evidence, on my say-so.",
"Yes, a falsifiable claim is one for which a person could conceivably prove it wrong. Verifiable is the opposite: something that can be confirmed. If I said that there are no blue-eyed people, that's falsifiable. Find a blue-eyed person. But it's not verifiable. What if you just haven't looked at everyone yet? I can always say you just haven't looked long enough. If I said there are mermaids, this can't be falsified. I can say you haven't looked hard enough. But it's verifiable: find one mermaid and case closed. A scientific hypothesis has to be falsifiable or else there's no way to know if it's wrong. An experiment is useless if it isn't capable of showing you that you're wrong. Otherwise you could just make all sorts of claims and no one could show you otherwise. Edit: this is why claims of aliens, conspiracies, Bigfoot, etc. persist: a true believer can never be conclusively disproven because their claims are not falsifiable.",
"At its simplest, yes. Something is falsifiable, if it is possible to prove it false. A statement that we can't possibly prove false inherently limits the practical value we can get out of it.",
"A falsifiable hypothesis has a test which could show that the hypothesis is false. If my hypothesis is that apples fall because of their skin, I could cut the skin off an apple and drop it and it if falls my hypothesis is false. Just because it doesn't fall doesn't mean my hypothesis is true, proving truth is harder, but it's not worth doing for non-falsifiable hypotheses. If my hypothesis is that people get sick because it's God's Will, there is no test that could prove this false. If I find some disease and it prove that it's because of some microbe getting onto the person, that doesn't falsify the hypothesis, because perhaps having that happen when the microbe is put on the person's skin is God's Will. Both \"caused by microbe\" and \"God's Will\" can be true at the same time without a logical contradiction. In science, perhaps the biggest problem in this area is string theory. It sure seems to hold the potential to explain a lot of things, but it operates with \"unseen dimensions\". That's too much like \"God's Will\", because by definition it can't be known. Early formulations of Quantum Mechanics had this problem. Einstein famously said \"God does not play dice with the universe.\" when the statistical side of the QM camp argued that the statistics were the actual facts. QM worked through that and most folks think that the world is actually like quantum field theory describes it."
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78r1m1 | Why do cars look like they are going faster the closer they get to you? | Other | explainlikeimfive | {
"a_id": [
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"text": [
"Your eyes do not measure linear velocity. They measure angular velocity. Lets take an example of a car moving 100 km/h in one second of time. At a long distance, it will look like it's moving slowly because the angle between where it was and where it is now, relative to you, is small. Now put the same car in front of you. It just crossed your whole 180 degree field of vision, and thus looks like it moved really fast."
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78r6jc | How can touch lamps be sensitive to touch while simultaneously being grounded/earthed? | Technology | explainlikeimfive | {
"a_id": [
"dow3ioo"
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"text": [
"There can be a touch surface which is grounded via a low resistance inductor. The inductor would not prevent the low level, high frequency signal used by the touch sensor from working. Inductors (block or reduce) the flow of AC."
],
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78rkry | How is low rep strength training different from higher rep size training? How do the muscle fiber grow differently to accomplish this? | Biology | explainlikeimfive | {
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"text": [
"Muscles work by snapping some muscle fibers under whatever stress you are putting them to, then replacing them with more fibers. This allows them to match whatever your needs are using only simple rules, a common theme across all of biology. While strength training, you're focused on the healing part more: you want more muscle fibers in exactly the places you need to strengthen the muscles you are training. Therefore, you do some reps to break a few fibers and then them heal up, making sure your body's systems can keep up with the healing. In mass training, you're trying to make your body massively overcompensate by breaking tons of fibers with long strings of reps, leaving little time for the healing process to begin. By breaking everything at once, the body rushes in to repair the damage, going overboard in the process so less damage is done the next time you do that. In addition, that many reps quickly runs your muscles out of oxygen, forcing those cells to begin building up lactic acid and burn through their sugar supplies very quickly. The lactic acid also damages cells and sends signals to the surrounding tissue which encourage vascularization, the growing of new blood vessels and widening of existing ones. The increased blood flow also helps bulk up a bit just due to there being a lot more fluid in the area now, and also creates the huge, prominent veins you see in bodybuilders.",
"There's different types of training which work on different kinds of muscle. You've got 2 basic types of muscle in your body, red and white. White is your \"power\" muscle, it's good for very short but intensive things. The other is red, which is your \"endurance\" muscle. The white fibers have little to no energy in them, and require energy to be stored close by in fats to be broken down and used. Because of this, these areas are where most fat is, and these muscle fibers will seem bigger. The red are packed with energy, and it's why they actually look red. These fibers aren't as powerful, but they can go for a very very very long time since they generate their own energy. (So long that the animal that can run the longest distance on Earth is the human) So by doing short intensive workouts, you're working on your white fibers. These build up the muscle and build up fats (this is why weight lifters will do a build-cut cycle) giving them a beefy appearance. When you go for a long run though, the white fibers run out of power almost instantly and the red take over. By training them, these muscles lean out and build up their ability to make energy to last longer. Since they don't need the fat right there, those fats are used up pretty fast and moved to other parts of the body. This is why runners often have almost a pear shape appearance, but 2 people working out with different routines will have vastly different appearance."
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78rris | packet buffering | why does it happen? and how? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"A train just arrived at the station. Lots of people leave the train. The escalator up can only load one person per second. All these people are now waiting for the queue in front of the escalator until it is their turn. That is what packet buffering is: More packets arrive than the outgoing link can transmit. Possible solutions are: * Get another escalator: Now you can load two persons per second! * Get smaller trains more often, that way less people are waiting each time as the load gets distributed over time. * Get the smaller or the important people on the escalator first."
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78rxt2 | Why can our ears handle the pressure from water or air just fine, but excessive loud noise can cause damage? | Biology | explainlikeimfive | {
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"There's a difference between damaging your ears, and damaging your hearing. Your ears, or more specifically your eardrums, can be damaged by air or water pressure. You may have experienced ear pain if you fly, or dive down deep in the water. Excessive pressure diffferentials on either side of the eardrum can rupture the disc. Although, this is temporary/repairable. Loud noises can damage your hearing by destroying the fine hairs and nerve endings within the cochlear.",
"On top of the other answers here...it would take a lot of pressure from an air compressor or water pump to actually get into your ear the way sound waves a can. You'd basically have to have the jet of water/air rip your outer ear apart before it could even get the direct application of pressure on your eardrum."
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78s43f | Centripetal force | Does it really exsist? This has always confused me, the reason being is, whenever it gets explained, the centrifugal force is said to be the reactive force, so if you are swinging a ball on a rope, the outward acting force (centrifugal) is an opposite and reactive force to the centripetal. That makes perfect sense. However the explanation about the centripetal force is that it is the force acting inwards, keeping the ball on the rope from flying away, you cut the rope, theres no more centripetal force, and the ball takes flight. Does this man its not the ball that has the centripetal force, but the tension on the rope keeping it there? If there was a centripetal force present, shouldn’t the ball keep its circular trajectory when the rope is cut? Or even make an arc instead of just flying off at a tangent? | Physics | explainlikeimfive | {
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"This confuses my intro physics students a lot. Here's the deal: despite the fancy name, \"centripetal\" is not a special kind of force, it just describes a direction, toward the center. Saying there's a \"centripetal force\" is like saying there's a \"force to the left\": you still have to say *which* force is acting centripetally. So for a ball tied to a rope, tension is the centripetal force. For a spacecraft in orbit, it's gravity: in other problems it could be a normal force, spring force, friction, or whatever. But should that force disappear for some reason, the object will stop traveling in a circle.",
"If I remember correctly, the tension on the rope *IS* the centripetal force. When the rope is cut, the centripetal force is removed.",
"It's a complicated matter because there's a fake force involved, existing only in a specific frame of reference. To start off, if you're standing still in your normal frame of reference, you can easily tell that to keep an object rotating in a circle, a constant force towards the center of this circle must be exerted. This is because there's no such thing as 'curved momentum' - an object, viewed as a whole, can only be moving in a straight line at any time. To keep it moving in a circle, you need to constantly apply a force to 'bend' it's momentum into the circle, constantly turning the line it follows. If you didn't exert this force, you stop turning its momentum vector, and it flies away in a straight line. The centripetal force is whichever force acts on your object to keep it rotating in a circle. In the case of your example, the force the rope exerts on your ball is the centripetal force. The real fake force is the centri*fugal* force. There's no such thing as a force pushing your ball outwards from the circle - it simply has inertia, and to keep it moving on a circle rather than in a straight line, as mentioned before, you need a constant force acting inwards. This is why fake forces such as these are called \"Inertial forces\". The reason it's perceived as a force has to do with frame of reference - and forgive me if this gets a little convoluted. If you're standing still in the room, and you see the ball turning on its string in front of you, it makes sense that if let go, it will simply preserve its momentum and fly away. However, if you put yourself in a *rotating* frame of reference, say on a rotating plate underneath that apple, suddenly your entire 'world', your entire frame of reference, rotates along with it. And now, suddenly, you perceive a 'force' constantly pushing you outwards. If you cut the rope to the apple, you'll keep on turning on the plate, but you'll see the apple gradually accelerate away from your platform because of the 'deficit' in force keeping it rotating. This is what seems to be a force, and is hence called the centrifugal 'force'. I don't have any imagery to make it clearer for the centripetal/centrifugal force, but the coriolis force is a very similar phenomenon, and this gif illustrates the difference in perception from different reference frames very nicely. URL_0"
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78sjrx | When people talk about ballistics why do they use velocity instead of speed? | Whenever I hear people talking about any type of ballistics they always say velocity when I'm pretty sure they mean speed. Like for instance they say "We need a greater velocity" not "The magnitude of velocity must be greater". Also, on a side-note I just watched a gun video where someone said this gun has a longer barrel so the bullet will go faster, why would the bullet go faster in a longer barrel? To me, that defies the law of conservation of energy. | Physics | explainlikeimfive | {
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"> why would the bullet go faster in a longer barrel? To me, that defies the law of conservation of energy. The bullet is propelled by the force of expanding gas the entire time it is in the barrel. Once it leaves the barrel, the gas is no longer bottled up, and escapes into the atmosphere instead of pushing the bullet.",
"They're just being ~~slopping~~ sloppy when saying velocity vs. speed. Speed is, indeed, the magnitude of instantaneous velocity. Maybe velocity sounds more scientific than speed, even though it is, indeed, wrong if direction is not given. The bullet goes faster in a longer barrel because exerting a force from the combustion gases over a longer distance results in more work done on the bullet, which results in more kinetic energy in the bullet. More of the potential energy in the hot combustion gases is being converted into kinetic energy of the bullet rather than kinetic energy of the air surrounding the opening of the barrel.",
"2 questions, 2 answers. 1: We weigh ourselves in kilograms, but I've yet to see a bathroom scale adjust for gravitational acceleration. They do mean different things in specific contexts, but in our context where it matters, it's understood what we mean by what we say. In the context of firearms, the technical term is \"muzzle velocity\" and so the common term is, unsurprisingly, \"velocity\". And in the case of small arms ballistics, there actually is a direction specified. Ballistic chronographs measure the time taken for a bullet to pass through successive vertical planes. This measures its horizontal velocity, whereas its speed includes its (negligible but present) downward motion due to gravity. 2: The relationship between barrel length and muzzle velocity is pretty simple. When your propellant powder ignites, it generates a lot of expanding gas. The barrel acts as a guide and the bullet as a stopper, forcing the expanding gas to push against the bullet as it moves down the barrel. The moment the bullet leaves the barrel, the gas starts to expand in all directions, and so stops imparting energy to the bullet. However this relies on there being sufficient propellant to make use of the full length of the barrel, and propellant that burns at an appropriate speed to maintain pressure behind the ever faster-moving bullet. As you have lighted on, there is a significant loss in energy as the bullet slides down the barrel. If there isn't enough or the right kind of propellant, there won't be enough gas expanding fast enough to continually accelerate the bullet as it goes down the barrel. In that case a long barrel would be a waste of energy."
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78svxp | How do we know so much about the sun? | I was watching a video the other day that happened to include measurements of the sun's various layers, and I was thinking "Mhmm, right sure", when a bigger thought struck me- "Wait, what?". I don't doubt that the information is genuine, but I hear all the time that we can't even begin to approach the sun because of how hot it is. So how do we know the various depths of the sun's layers? How did we get a probe close enough? Is it done through estimation and educated guesses alone? | Chemistry | explainlikeimfive | {
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"> How did we get a probe close enough? Is it done through estimation and educated guesses alone? Well although we have sent satelites to study the sun, none have got particularly close. Estimation and educated guesses are certainly part of it, but it's really a case of being able to infer greater and greater information through observing it's behaviour, and coming up with testable theories that explain that behaviour. For example we can measure the size and mass of the sun through a combination of geometry for it's size, and careful measurement of the movements of the planets let's us work out its mass. Spectroscopy tells us what it's made of, and an understsnding of how gases behave in different circumstances let's us extrapolate how hot, and how much pressure the gases must be under at the core.",
"The other answers are great for how we can work out the size, mass and composition of the sun, as well as temperature etc, but you asked about the Sun's layers and this is a chance for me to break out one of my favourite words: Helioseismology. Just like we worked out the inner structure of the earth by studying how the seismic waves produced by earthquakes travel and bounce off boundaries etc. we can do the same with the sun! Now, the sun doesn't exactly have earthquakes in the sense we have them on earth, but it does have similar \"quakes\" caused by things like solar flares, and by making careful measurements we can see how those waves propagate through the sun. We can even use this to \"see\" sunspots on the far side of the sun from us!",
"Here is the nice thing about the sun - nothing it does is small. You want to set up some kind of quantum experiment and you need devices to measure single photons that zoom around at the speed of light. You are trying to take the most sensitive of readings to detect absolutely tiny values. You remember those cartoons from when you were a kid of this giant chemistry set boiling and bubbling away to produce a single, precious, drop of something at the end of the process? That's the majority of science. Trying to grab that tiny, tiny, little thing at the end. The sun is like a fire hose that just BLASTS data at us. Our biggest problem with observing the sun is making sure we don't go blind from the sheer volume of data being hurled at us. That makes getting measurements and readings pretty easy - if requiring specialised equipment. Yes, we can't go and get a scoop of sun goop and bring it back to earth to experiment on, but what does it really matter? We can observe how it behaves from a distance just fine and deduce a great deal about it based on that."
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78tqmn | Why are human babies so useless compared to other animals? | Biology | explainlikeimfive | {
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"Human babies are born relatively earlier than a lot of other mammals. This is due to the size of the baby’s head and mother’s pelvis. If human babies gestated longer, they would become stuck."
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78u1p9 | Why do things lose their color when they're under the sun for too long? | Chemistry | explainlikeimfive | {
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"It is called bleaching. The sun is bright with a full spectrum of radiation in the visible spectrum. Color is due to pigments which are complex molecules. A lot of the sun's radiation is absorbed by the pigment. The color is due to some of it being reflected. A small part of the sun's radiation is energetic and will destroy the pigment eventually. You have pigments in your eyes which respond to light penetrating your eyes. That is how you see color. The pigments are changed by sunlight of a particular color. The pigments have to be continuously rebuilt to keep you seeing in color."
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78u6c9 | Stoke’s Theorem and Maxwell’s Equations | Why does stokes theorem work and how can we be certain that Faraday’s Law and Ampere’s law obey this type of behavior? Why does the “twisting” of a field cause the other coupled field to change in time? | Physics | explainlikeimfive | {
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"Really good question, but this might be a little too broad and deep a question for ELI5, especially since you're asking for proofs. A good answer would involve reviewing about a quarter of a standard undergraduate electricity and magnetism text. If you want todo that, I recommend Griffiths, *Electrodynamics*, sections 1.3.5, 5.3, and 7.1. > Why does the “twisting” of a field cause the other coupled field to change in time? One quick correction on this though: you've got cause and effect backwards. The usual interpretation of Faraday's Law is that changing magnetic fields *cause* swirling electric fields, not the other way around (even though formally, the equation doesn't specify which causes which.)"
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78uaed | how do self balancing bikes work? | Eli5: such as Google's self balancing bike. Or I've seen a concept of a motorbike that can't fall. How are they able to offset the weight when the bike is unbalanced? What is this magic? | Technology | explainlikeimfive | {
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"I'm not sure which Google bike you mean, but if it's this one: URL_0 I have to dissapoint you because it's an April 1st joke...",
"In short, angular momentum. (On mobile here, so sorry for any typos in advance) So just like how an object moving in a straight line will continue to do so into an outside force stops it (like friction), objects that spin will want to continue spinning. The first is linear momentum, the second is angular. Whenever an instability in the spin happens, the entire system will shift to try and maintain its overall rotation. This is why it's easier to stay upright on a moving bike compared to a stationary bike. The wheels want to keep moving around the axle. As soon as you start to tip, the wheels are now also rotating in another direction. Any bike with spinning wheels will try to right itself some, but is limited based on its rotational speed. The super fancy bikes will have gyroscopes installed that can be sped up via computer controls to counter and rotation due to falling over."
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78ug78 | How does a program know what I've clicked on? Is it constantly checking each and every button region for a click? If so, could increasing the number of buttons on a screen slow down a program dramatically? | Technology | explainlikeimfive | {
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"Programs have mouse readers; when you click the mouse button, your computer sends the program the x,y coordinates of your mouse and the program \"registers\" a click in that location accordingly",
"You don't need to check continually for a button click and location you only need to check when the click actually takes place. So \"On click\" check what mouse button was clicked, where it clicked and what the active application is and then decide what was clicked. You don't check per button but per click.",
"Developer here, When you move the mouse, it's circuitry produces a message it's going to send down the wire or over the air to a receiver. This event will eventually trigger an interrupt. An interrupt is either a hardware or software event that tells the environment to stop what it's doing and address this issue immediately. Interrupts are enumerated, and there's a table of offsets to program instructions that handle that kind of interrupt. So whatever software gets kicked out of the CPU core, the message is dispatched to the hander which gets executed. The event gets passed to a hierarchy of event handlers (a specific kind of function called a callback in the more general case), software you're running that is even interested in these sorts of things. Typically it begins with the top window that got clicked on (the desktop itself is a window) and on down, through other programs that might be interested. What the program does is up to what the developers put in their programs. If the click is in some region that doesn't do anything, then the callback is done. Otherwise, the program goes on to do something about it. GUI programs have what is called an event loop, which enters a \"blocking\" state. It's waiting for a message to come through; in the simplest case, the program gets no CPU time because there's simply nothing to do. The OS has a \"scheduler\" that is involved in managing which programs get how much CPU time in what core, and the program gets woken up. In the loop, you decide what to do, if anything, do it, and go back to the beginning of the loop, waiting. This is event driven programming, and in a very simple model of a computer, the CPU will have an idle instruction, and the whole computer could get away with literally doing nothing until an event triggers action. Your desktop CPU is far more complicated than that, of course, so no such thing like this would happen on it these days. Even the blinking of the colon on the clock is event driven, causing a cascade of activity. There is a way to do the same thing in a non event driven, non blocking way, and that's polling. What this is, is you store the last known state of the mouse, and put in a loop logic that goes to the mouse and checks if there's a difference, if the state changed. \"Are you different? Loop. Are you different? Loop. Are you different? ...\" The CPU will cycle as fast as it can, just checking. The problem is a scenario where the mouse moves, and then move back, or a button is clicked then released, before the program had a chance to check again. Polling is just a technique in the toolbox, and there are scenarios where that's the only option, for example, if you wrote a program that checks if the TOS of a website, software, or service has changed - you know, if you've read one of these things, they say subject to change without notice... So anyway, polling isn't necessarily a good fit for a mouse."
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78uh8l | Why do we get out of breath less, the more we exercise? | Now, I understand muscle fatigue and muscle pain. I also understand how muscles get better and stronger with exercise. The question is not about that (unless it is somehow correlated). But you know, when you are jogging, for example, at some point you get tired - and it's not because your legs are hurting. If you keep running at this point you will get a sharp pain close to your liver (at least I think this is where the liver is). It is also the reason why trainers teach you the importance of breathing well - because it somehow helps delay the "getting tired" part. This effect is particularly strong when you are a relatively "fit" smoker - your body can somehow handle exercise, but your lungs can't. What is really happening? And why is it that the more we exercise, the less out of breath we get? | Biology | explainlikeimfive | {
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"Your heart is a muscle, when you exercise it gets stronger and moves blood more efficiently. Same with the lungs, the more you exercise them, they more efficient they become at transferring gases. Oxygenating your blood while carrying off carbon dioxide. So when your heart beat goes up and you are moving more blood, your lungs have to breath faster to keep up. So a stronger heart is more efficient and beats less to move the same amount of blood. Also your lungs don't have to take as many breaths to transfer the gases in and out of your blood."
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78uz46 | How solar cells transform the sun's energy to electrical energy | Physics | explainlikeimfive | {
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"**Short Answer** Shine light on the right type of semiconductor and electrons get knocked loose, resulting in useable electricity. **More Detailed Answer** 1. Build a molecular antenna that can absorb solar radiation and use it to promote electron density into an excited state. 2. Attach the antenna to a *d*-metal, such as ruthenium, that is sensitive to excitation in its antenna and that can readily promote an electron to a higher energy state (pi- > pi*) where it is more easily extracted. 3. Have a semiconductor nearby that can extract the promoted electron from the metal center, creating usable electricity. Generally, systems use what are referred to as \"dyes\" as the antenna. These are extended conjugated systems where electrons can move readily across extended pi conjugation. They usually incorporate an aromatic ring as the absorber. The Ru^2+ / Ru^3+ system is a popular metal center. The conduction band of titanium dioxide is used as the method of extracting the final electron. An separate reaction regenerates the Ru^2+ from Ru^3+ and the system is ready again. Lots of modifications and optimizations can be made, especially with the details of the antenna, to increase efficiency and decrease cycle time."
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78v8xj | How does thread count work and what makes higher numbers better? | Other | explainlikeimfive | {
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"Thread count is the number of threads per unit area (inches in the USA). More threads in the same area means that the threads are smaller. This makes the cloth have less texture and it generally makes it more flexible. So, higher thread count sheets or towels appear to softer and more pliant. Lower thread count means the cloth will feel rougher and be stiffer.",
"Imagine that a program is a road, and a thread is a car. Each thread knows where it is along the path, and takes some time to get to the end. How much \"work\" your program has to do is akin to how long the road is. Most old programs were written to be single-threaded. That's like a road with one lane. You can only fit one car down the road at one time, no matter how fast it goes, and that one car has got to travel the whole distance. Nowadays you can write programs to be multi-threaded. That's like splitting the road into multiple lanes- now you can fit more cars on the road. A multi-threaded processor gives you more cars, and so overall you're moving more distance at the same time. Your processor's clock speed is like how fast each car goes. Let's say your program was written for one thread. No matter how many cars you have, you can only put one on the road at a time, so it's best to have a really fast car. So a 60km road with a 60km/h car would take 1 hour to complete. However if you have a program that does multi-threading exceptionally well (\"map\" in functional languages is beautiful), it's like having a road that magically splits itself for as many cars as you can throw at it, down to the minimum of say one km per segment. Say you have 8 cars that go at 30km/h. You'd finish the course in 15 minutes! And if you had 60 cars running at 15km/h (like some of my machines), you could complete it in 4 minutes. Of course not all programs are written to take advantage of multiprocessing, and there's usually a cost involved in splitting up the road segments. Let's say each split takes up one additional km of distance. Splitting it into 8 segments gives you segments that are 8.5km long each, for a total of 68km. With your 8-car 30km/h setup, that's still completed in 17 minutes. Splitting it into 60 segments, and running it off the 60-car, 15km/h setup doubles the workload to 120km- but you'll still complete it in 8 minutes! This is where you need to think carefully about what sort of work you're doing and what kind of processor would best serve it- a high core count, average clock speed processor, or a low core, high clock speed processor. For most uses a quad core 4GHz is better, since most user-friendly programs do not multithread very efficiently. For servers and dedicated processing machines, and where the cost of splitting the task is low, a *pair of* 16 core 2.6GHz chips fares much better. It will play Doom slower than the 4GHz though!",
"The other posters are correct in that a higher thread count for cotton sheets or other natural fabrics mean softer sheets, up to a limit. After about 600 thread count you move into man made fabrics such as polyester, nylon, etc. at this point this number no longer matters and results in a different feeling Example: 150 thread count cotton sheets will feel rough especially compared to 600 thread count cotton sheets. 1000 thread count polyester sheets will NOT necessarily feel better than 600 thread count cotton sheets as they may breathe less and hold in more static and heat.",
"In the English system, the number after the diameter is the threads per inch count. So a 1/4-20 bolt is a 1/4 inch in diameter and has 20 threads per inch of length. Example, a fully threaded 1/4-20 x 1.5” bolt has 30 threads. Don’t mix threads! A 1/4-20 bolt and a 1/4-28 nut do not work together. Edit: higher threads per inch helps with self locking or fine adjustments. In addition, their torque values are different",
"Depends what youre talking about. Computer processors? Fabric? Internet posts?",
"If you were talking about computing: A thread (in Computing) is a sequence of instructions for a CPU to execute to accomplish a final goal. every process uses a thread, and some may even use more than one if it has to do a bunch of processes at a time (eg: playing a game or processing a video). Every core (at least from what I've seen) has 2 threads. ~~That means your 4-cored i7 will have 8 threads, and a Ryzen R7 with 8 cores will have 16 threads.~~ (Edit: it seems that I'm wrong. Cores have one processor, but things such as Hyperthreading (and any SMT) will create a virtual 2nd thread.) The reason to have more threads is pretty simple, more thread- > more 'brains'- > more simultaneous processes. If you're talking about clothes (or whatever): I have no idea when it comes to cloth, but searching around the internet it seems that thread count is the number of horizontal and vertical threads within one square inch of a fabric. The reason higher numbers are better will probably make sense just from that. More threads/square inch means better coverage, which in turn means greater insulation. Though, from my research, it also seems that the [thread count does not matter as much as the material and weave.]( URL_0 ) Edit 1.1: -fixed bugs (typos) -clarified some vague sentences. Edit 1.2: Fixed incorrect info.",
"Here's a [short video with a solid ELI5 explanation]( URL_0 ) Also worth mentioning that a lot of companies just lie about thread count... much like \"100,000 lumen\" flashlights and \"100,000,000 volt\" stun guns, a lot of times \"2,000 thread count\" sheets are just outlying lying on the assumption the consumer will never test it.",
"To insert more beyond your question, in terms of bed linens, op: The numbers themselves don't mean all that much in terms of quality in real life, since different fibers can affect how sheets feel, but more so because there is an *incredible* amount of lying in the bedding industry. In March, the US International Trade Commission found a “widespread pattern” of “grossly inflated” thread counts, one sheet being advertised as 800 thread count, but was in fact 250. [Here]( URL_0 ) is the Washington Post article about it for more. Going back to different fibers: a lot of \"Egyptian Cotton\" sheets were pulled from retailers last year, because they weren't really Egyptian Cotton (per an article in [The Guardian]( URL_1 )), but even that isn't quite what it sounds like because Egyptian Cotton doesn't refer to a specific type of cotton that is luxurious, just any cotton grown in the country of Egypt.",
"here's an old comment from buyitforlife that I saved... URL_0 credit to u/jessthepest",
"Well this thread wound up faster than I ever expected! Thanks for all the awesome answers and explanations! I never realized my question was actually quite vague and I ended up getting a hilarious variety of responses because of it. I was having a pretty crappy day when I got up but reading through everything made it awesome! And to summarize the answers we so far have ***6*** different types of thread counts! Sheet thread counts (my original intent). CPU thread counts. Rope thread counts. Nut/Bolt thread counts. Pipe connection thread counts. And last but not least, Internet post thread counts!",
"If you're asking about bolts and screws I can help! In SAE (Imperial) threads are measured by the amount of threads in an inch. So, on a 1/4-20 will have 20 threads per inch, while its finer threaded brother the 1/4-28 will have 28 threads per inch. In metric, the thread count is the distance between the first thread and the next. So, a M2.0x0.4 has .4mm between the first thread and the next. Metric threads begin their fine threads at much larger sizes screws, the smallest standard sized fine metric thread is the M8x1 which has an entire 1mm between the threads! The finer threads are for measurement, adjusting, small, or fragile equipment.",
"For sheets higher number isn't necessarily better. You're looking for something between 300-800. Any higher and there won't be enough room between the threads for air to flow properly will also feel like sand paper."
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78vf49 | How are stock prices determined of publicly traded companies? | Economics | explainlikeimfive | {
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"Supply and demand. That's all. More entities want to buy - price go up, more ones want to sell - price go down. The reasons why someone want to buy or sell may be pretty any.",
"Before a stock is \"floated\", the company's accountants estimate what a good share price would be, based on their knowledge of the company's financials. After flotation, the market decides: the stock is worth whatever someone will pay for it. For example: before Facebook's initial public offering (IPO), the opening price was revised upwards several times, and it started trading at $38. Other analysts at the time valued it at $40, on the first day it struggled to stay near the opening price ... but today the price is $170 - because someone's willing to buy it at that price."
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78vrx7 | Are there any noteworthy differences between a name brand medicine and the generic version? | Chemistry | explainlikeimfive | {
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"Generic drugs work the same as name-brand drugs. ([Source:]( URL_0 ) Food and Drug Administration.) This is a standard they have to meet to be approved for use. In particular, generics must: * have the same active ingredient * have the same strength and administration method * have acceptable inactive ingredients * be manufactured under the same standards as the name-brand * provide the same clinical benefits",
"I can think of exactly two. Levothyroxine. Name brand is Synthroid. My mail order pharmacy simply refuses to fill generic L-thyroxine. Dosing for this drug must be very precise, and Express Scripts simply doesn't think the available generics are precise enough. Submit a generic script for L-thyroxine and they will fill it with Synthroid - at the generic price. Similarly Creon, which is a biologic - pancrelipase. There are generics but there have been potency issues with them.",
"My birth control got switched to generic and it made me quite sick. Some people had the same reaction, some people said we were full of shit. Either way, back on my normal pill and my pain stopped.",
"**tl;dr: Nothing significant** For the vast majority of drugs (eg. tablets, capsules, liquids) the only difference between a brand and a generic are the inert ingredients. The active ingredient is the same and is in the same quantity as the brand. The other ingredients are things like fillers, binders, lubricants, etc. that basically assist in the manufacture of a product or help it dissolve better. All of these other ingredients are FDA approved to be used in medicine and for the most part, the manufacturers all use basically the same ones. The amounts may vary due to the equipment used to manufacture, tablet size, shape, color, etc. A generic drug still has to go through a rigorous process in order to get approved. The main difference is that the generic manufacturer does not have to do clinical trials. Clinical trials are where a medicine is tested in people to make sure it works properly. The generic manufacturer only has to prove that their product has the same active ingredient, and same properties as the brand (dissolving time, quantity of active ingredient, etc.) This is because the brand name manufacturer has already proved that the drug has a positive effect in patients. There are some drugs where it is preferred that a patient stay with a same manufacturer. These are usually drugs where small variations in the amount of the active ingredient can lead to adverse effects. An example of this is levothyroxine which is a drug for hypothyroidism. The drug is dose in micrograms and comes in many doses that are only 25 micrograms apart. While manufacturing is quite precise and accurate, when you get down to a level like that, there can be just the tiniest amount of differences between manufacturers that can have a real affect on the patient. For reference, a single grain of table salt can weigh something like 50 micrograms) There are newer biologic drugs that are being referred to as biosimilars which isn't quite the same thing as a generic drug. These are drugs that are large complicated proteins like your monoclonal antibodies or \"mabs\". When a biosimilar is created, it has the same chain of amino acids that make it into the same protein (active ingredient). One of the main differences is that proteins get chains of sugars attached to them and these can vary from brand to generic. With these large protein drugs, an issue is that sometimes the human body will mount an immune response against the foreign protein. The risk of this immune response can vary based on these sugar chains attached to the protein. So in the case of biosimilars, the FDA has opted to approve them with a suffix at the end that specifies the manufacturer of the drug(eg. filgrastim-sndz is made by Sandoz). Source: Pharmacist with experience in drug manufacturing.",
"My dad works in a pharmaceutical company that makes generic medications so I might try to answer your question. Generic drug has the same active ingredient as a brand medicine. However, knowing what kind of molecule we need to put into your body is not all we need to make sure that we will cure you. To put it simple, every medication has the minimal and the maximal level of concentration in the blood. If you have not enough medication in your blood it does not work, if too much it causes harm. Every single medication behaves differently in terms of getting into your blood and being “neutralized” by your liver; so we have to find a different ways to deliver different drugs. That’s why there are so many different types of pills, dosage forms etc. Pretty much the better we control the concentration of active ingredient in your blood the more efficient the medication is. When Phiser puts billions into new formula then can afford to spend 100M to find a perfect dosage form for the drug as well. However, when no name company makes a generic version, they only put 10M into research so they will stick with the first result that passes the government regulations. Keep in mind that generic creator needs to find investors for R & D while the brand owner has already recouped all their spending during the years they had a patent. You might ask a question: but why can’t I make my generic drug equally good or better than brand name and still spend only a portion of what brand owner spent. The answer is because you spend money on R & D and they don’t, if you try to compete by quality the brand owner will price their brand cheaper than yours and you’ll go bankrupt. Generic drugs can only compete by price but no by quality. Of course what I’ve written here doesn’t mean that generic drugs are bad. As other mentioned before me all generic drugs have to be safe and efficient. However the more complex the drug is the higher chance that it will be less efficient than brand name.",
"There was an interesting study on this and while chemically there is not much difference, if people feel the brand name one is better then it works better. Psychosomatic or placebo affect can be really useful with drugs. So if you believe generic works as well it probably does and if you think brand then it probably does. Unless it's something super specific of course. I'm talking mainly about paracetamol or aspirin.",
"They might have slightly different release mechanisms and fillers. I was prescribed venlafaxine for depression. I got a generic brand and it worked great. After a few months I got a different generic and everything just turned to shit. I felt sick constantly, my gut and joints ached and I felt miserable for like 4 weeks. I tried switching back to the first generic I had and everything went away after a few days. I can't say for sure it was because of the brand change but it sure seems like it. Looked at the ingredients and the fillers were quite different. Most notably the \"bad\" brand had SLS (sodium laureth sulphate) in it, which is an inflammatory agent and an irritant. Maybe was related to that, maybe not.",
"There is ABSOLUTELY a difference between the two. Almost 100% of the time this question is asked online - or especially to a health care practitioner - the answer will be no, there are no \"major\" differences. As with most answers so far in this thread... This is because with generic medications, the active ingredient indeed must be identical to the brand name active ingredient. As someone has already mentioned - the differences are fillers, lubricants, etc., which are often ignored and should not be. Allergies are of course important here, and very uncommon. That's not what I'm talking about. Fillers (for example) can cause a difference in delivery and therefore effect - not as a placebo, but in someone who's not expecting any difference. ADD medications are a great example because amphetamines cause a very noticeable effect in the human body (whereas something like Ibuprofen has a less noticeable effect). *Many* patients that switch from brand name to generic ADD medications - or **switch between generics** - notice differences. Heart palpitations because the active ingredient is suddenly hitting the bloodstream too quickly, ineffective administration because a patient metabolizes certain fillers differently, etc... The reason this isn't talked about more is because the pharmaceutical industry is pretty full of special interests. Especially within the FDA... it kills me that whoever cited them as a source is currently the top commenter right now. One generic form of medication will be manufactured in a VERY un-FDA approved facility in India, but when it gets past our borders - Boom. FDA approved because the active ingredient is the same. The \"same\" pill manufactured by a different generic *brand*, might be made in a top notch facility in the U.S. Long story short: if you need or want to change to a generic medication, **research the specific generic that you intend to switch to**. Most pharmacies will allow you to call and ask what they literally have in stock, which can vary immensely, and can definitely make a noteworthy difference in your treatment. Edit: As u/cdbloosh mentioned above, there are few cases in which brand name and generic medications will have a noteworthy change in effect. I agree with that. My point is the ones that do, which is why I mentioned ADD medication specifically. Highly prescribed and a pertinent issue in this regard.",
"I used to work for a large pharmaceutical company that produced both generic and name brand medication in the same factory with the same machines using the same process.",
"Sometimes, yes. While the amount of the active ingredient is the same (within certain guidelines), the metabolism can differ due to the binders/other ingredients in the pill, which can cause some generics to not work properly or at all. See: Nardil reformulation, or the Bupropion/Budeprion scandal URL_0 When people originally complained about Budeprion not working as well as Wellbutrin, the FDA basically said \"well these people have mental illness, you can't really take them seriously!\". Turns out, there WAS in fact a huge difference and Budeprion didn't work at all for many people."
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78wrvf | What is the relation between GDP and inflation rate ? | Economics | explainlikeimfive | {
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"Plain terms here: GDP is how well the economy is doing - how much money there is. Inflation is the increase of price levels, or decrease of purchasing power of money. (Two sides of the same coin) GDP and inflation are connected because of the unemployment rate - that’s how many people in an economy don’t have a job. This is the connection: as economy starts doing better - GDP rises, companies have more money and therefore can hire more workers lowering the number of people who don’t have a job - unemployment rate. Low unemployment rate causes inflation because it increases demand, (thanks to more employed people with money to spend) without necessarily increasing supply, which causes prices to rise. Also in a market where companies have to search for workers instead of workers searching for companies (low employment), companies will have to spend more (expenses) to secure the best workers which will once again lead to a price increase. Don’t forget though that in economics there is never a ‘right’ answer or solution - otherwise we wouldn’t be facing constant economic troubles all over the world. Not all rules work all the time and it all depends on great many things, but that’s it in a nutshell."
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78x0kl | If someone is addicted to a substance (drugs/alcohol etc) and have an illness/ accident causing them to be in a coma for a long period, will they still be addicted when they wake up? | Biology | explainlikeimfive | {
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"Unless the people caring for that person during the coma kept giving them whatever it was they were addicted to, then no. However, that person wouldn’t be chemically addicted to it but mentally, so they still want it just because they might still associate the substance with being happy."
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78x8jt | What do cell phones do with the information it gets from SIM cards in order to make a phone call? | Technology | explainlikeimfive | {
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"Take it roughly the same as how authenticating yourself on a private, wireless network. Your SIM card ID is a username, your PIN unlocks the SIM card's \"password\" equivalent (your pin isn't used on the network, it unlocks the second encrypted part needed to complete the authentication). Once the SIM full ID is unlocked (and your phone accessible), you get access to your account's credentials on that network (remaining credit and the like) and you can make calls (other than emergency ones). And for the reason about Vsims like VSCA or any other .. these take time, it has to come from cooperation and make the insane paperwork, adopt standards for network operators AND phone manufacturers and face the potential loony, obnoxious one who wants to do his own thing with zero standard whatsoever (hello Apple) and will probably make the others do the exact same thing : divide & conquer (hello everyone else)."
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78xadd | What is the SALT tax deduction, specifically how does it affect people? | Economics | explainlikeimfive | {
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"SALT (State and Local Tax) is a deduction that allows people to deduct state and local taxes from the income they pay federal tax on. Advocates say \"It's not fair to be asked to pay income tax on money that I didn't get to spend because the state government took it.\" It subsidizes states with high taxes, and that upsets folks in other states."
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78xb0l | How can a central bank set a negative interest rate and why? | I've read a few lines online but I'm still puzzled as to why would central banks set negative rates? How can they maintain it and why would investors buy stocks or bonds with negative interest rates? | Economics | explainlikeimfive | {
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"It's a rare circumstance that nominal interest rates are actually negative, because you're guaranteed a 0% interest rate by holding cash. What's more common is that real interest rates are negative: the interest they return is less than inflation, so in the end, you get back less than you put in. If the interest rate is 2%, but inflation is 3%, the real interest rate is -1%. That still beats your 0% cash, which would have a -3% real interest rate. A negative nominal rate is only possible if, for some reason, cash is unsafe, and you're essentially willing to pay the government to store and protect your money. You can only hide so much under your bed (and that's not perfectly safe), and banks can fail."
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78xxv1 | Physical currency can't just disappear. In a crash like the great depression (where the money ends up in nobody's pocket/bank account) where does all the money that was previously in circulation actually go? | Using the Great Depression example... Before the depression hit, there was obviously a fair amount of money per person in circulation. Then the depression hits and nobody has it anymore. Where did it all go? To companies, the government, other countries? I just don't understand where the money that left those people's pockets ended up, since nobody seemed to end up with it. | Economics | explainlikeimfive | {
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"Most of the world's wealth is not represented as physical currency. In fact, physical currency makes up only a small portion of the world's supply of money. In the event of a stock market crash like Black Tuesday in 1929, what happens is that the value of stocks go down, so the amount of money people have goes down with it, even if not a single physical dollar is created or destroyed. Think about it this way. Let's say you own a house that's worth $100,000. Even though that $100k isn't represented anywhere in terms of dollars, you still *have* that wealth. You can take out loans against it, and theoretically sell it. Now let's say the situation changes. The city you're in builds a landfill and maximum security prison next to your house. The value of your house drops, and now no one wants to live there. Where once your house was valued at $100k, now it's only valued at $50k. Even though not a single physical piece of money has been created or destroyed, you've lost $50k. Replaces houses with 'stocks', and make this happen on a massive scale and you have what happened in 1929. The wealth represented by those stocks didn't go anywhere. It just disappeared.",
"The amount of money available to use at any given time is the amount of physical currency in existence multiplied by the velocity of money. The velocity of money is a number that tracks how quickly people spend the money they have. To show how this works - imagine an economy that has a total of $100 of physical currency in it. If you want to see how much money is available to be spent each month you have to first determine how quickly people are spending that money. If everyone in our pretend economy spends all of their money every month, then there is a total of $100 available to spend. If everyone spends 1/2 of their money every month, then there is $50 to spend. If everyone spends 1/4 of their money every month then there is $25 to spend and so on. This also works on a yearly basis. If everyone is spending all of their money every month, then the total amount of money available in the economy per year is $1,200, so having a velocity of money of 12 (everyone spends all of their money 12 times per year) has turned $100 in hard currency into $1,200 of effective money. The velocity of money is something that can change quickly, and falls when there is a crisis that causes people to lose faith in the economy as people hoard their money. During the great depression the velocity of money fell by about 1/3, and so there was a corresponding decrease in the amount of available money."
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78y8gu | On Windows (and possibly other OSs), why is the system's only recourse in the event of a software error to completely nuke the program? | Technology | explainlikeimfive | {
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"It is the latter option. Bugs, errors, and glitches happen all the time, and most often they end up fixing themselves or just terminating and trying again. You can look at countless video games to see this is the case. They rarely break programs. It's just that occasionally one will crash you out.",
"That's really not how it works. It's up to the program to catch it's own errors and deal with them. In the Olden Days, if that didn't happen then that program could take other programs (including the OS!) down with them. So now OSes put a cage around programs. When they misbehave and can't handle their own mess, the OS nukes them.",
"> system's only recourse This is simply not true. Most software errors *don't* result in the program being nuked. It just goes on running, with or without an error message, and with or without a visible impact on its action. For example if a program asks for a nonexistent font, typically another font is used, and it just goes right on running. You're just looking at the *most severe* errors.",
"When a bug happens, it's something unforeseen by the programmer. It means that the program is an unexpected state, or a condition thought to be impossible to reach. When this happens, the program (and the system) have two options. They can either kill the program immediately. Or, they can try to muddle along and make things work as best they can. The problem with trying to muddle along is that you have literally no idea what's wrong with the program's internal state. And letting it continue to run could cause a lot more damage, like unrecoverable data corruption. Therefore, it is better to just kill a program immediately when it runs into a bug whose occurrence was not foreseen. Think of it like driving your car on the highway. You press the brake, and you are terrified to find out that it doesn't work. You can either try to gradually slow the car to the stop with the emergency brake, then get out and take the bus. Or, you can try to keep driving, using the emergency brake as necessary. Which sounds like a better plan?",
"> Or am I simply not seeing the countless errors and bugs that the software does continue on from as normal, and is it only the Ebola-level errors that cause the software to forcibly close down? This is the case. Programs are generally written to deal with a lot of \"normal\" scenarios. But there are other scenarios that aren't normal, but they imagine they could happen. For example, if you let users browse files, and then let them delete them, sometimes you'll encounter an issue where the file no longer exists (it was deleted in another program). That's often referred to as an \"exception\", it's not common, but programs should be written to handle those situations as well. So really good programs will handle all of the conceivable exceptions that their code could cause. BUT there are always some exceptions that can't be handled in your code, not in a meaningful way. For example, if your program uses up too much memory, there rarely is a way to recover, so it'll crash. So what you're seeing when this happens is one of three things: * There was an exception they could have handled, conceivably, which they failed to. * There was an exception they noticed, but realized if this exception happened, there's no way to recover * There was an exception they couldn't catch (like out of memory) and the program basically gives up out of their hands. I'd wager the majority of the time, it's the first case. It's really hard to catch all the exceptions.",
"When you get that message, it doesn't mean \"there's a bug in the software\". Windows doesn't know or care how many errors there are in a piece of software. What it cares about is when the software gets so buggy that it tries to step on Windows' toes. That message most commonly indicates that the application tried to access memory that didn't belong to it. When that happens, the OS is notified, and since the application doesn't have access to the memory location it's trying to access, there's no option but to halt the program. Programs can contain as many bugs and errors as they like. The OS only stops them when they violate its rules and try to do something they don't have permission to do. So if you want an analogy, think of the OS as hosting a party. As long as the guests are just getting drunk and vomiting over themselves or accidentally sitting on another guest's glasses or spilling beer on the floor, that's ok, you can live with that. There's going to be some cleanup afterwards, but that's to be expected when you're hosting a party. But if they start actually breaking your furniture, or if they start trying to knock down the wall to the neighbor's flat to see what's in there, you're going to have to stop them and kick them out. Once they start trying to cause actual damage to your property (the OS) or to your neighbors (other applications running on the system) then it's \"Party's over, everybody go home, it's been nice seeing you, but you've got to leave *now*\". At that point, you simply can't tolerate what they're doing, and you have to shut the whole thing down. And that is what this error message means. It means that the program wasn't just doing stupid things, it was trying to do something that would harm the rest of the system."
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78yqrl | Why a physically larger brain doesn't necessarily make you smarter. | Biology | explainlikeimfive | {
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"It's a good question. And like most neuroscience questions, the simplest and most honest answer is: we don't know. We do not know the physical properties of a brain that make it a \"smart\" brain. Sure we have some guesses, but actual answers? Unlikely. So what it appears that your data has shown is that brain size is NOT a major determinant in intelligence. Now, from the start, I think most neuroscientists would not be particularly surprised by that. There are parts of the brain that really are highly unlikely to have anything to do with intelligence (irrespective of how you define intelligence), for instance the cerebellum, which as it turns out elephants have the largest ones of (relative to the rest of the brain) in mammals. The cetaceans, like whales and dolphins, many of which also have larger brains than humans, also ha also have a very large cerebellum. And this is a BIG structure in these animals. For instance [here]( URL_1 ) is a photo of an elephant brain, with the cerebellum circled. So if we were going to try to compare intelligence and brain size, we should probably remove the cerebellum first. Now typically, a lot of neuroscientists think we should actually compare the size of the frontal cortex if we were going to think about how intelligent animals were. I'm not so convinced that is actually fair, but still, if you take that assumption, then humans tend to look much better. [Here]( URL_0 ) is a whole article on it, if you're interested."
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78yvz8 | How do birds know which direction to fly when they head south for winter? | Biology | explainlikeimfive | {
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"Many birds have a sense of magnetic field that allows them to know direction and travel to the right place. Many sea turtles also have that sense. Many birds also have a sense of barometric pressure as well, which is why you can often birds leaving an area before a storm."
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78ywo5 | How do we find the valuation of a company? | Does it have anything to with EPS, NPV or IRR? | Economics | explainlikeimfive | {
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"This is an incredibly complex topic. People have written 1000 page textbooks on this topic, but here's a simplification. **Any** investment is worth the sum of the present value of the future cash flows. Stock, bond, entire company, annuity, lottery ticket, doesn't matter. It's calculated as the sum of the expected cash flows after they've been discounted by a rate to count for the risk. [Here's]( URL_0 ) a picture in case the visualization helps. So if we want to know how much a company is valued, we predict how much cash we'd generate and adjust it for the risk of t phe company. This is basically an NPV. IRR is the discount rate that will make the NPV 0 (including the price of the investment). So, you're probably asking, *It's almost impossible to accurately assess both the risk of the company and the cash it will produce. How does is this method reliable at all?\" Well, by in large, it's not, so you're predictions will be affected by what side of the deal you're on. If you're looking to invest, you're predictions will be conservative because you want to know how much you can make if the company does poorly. If you're looking to sell you're company, you want to show it in the best possible light, so your predictions will be better. But, to try and tether our predictions to earth, often times people will look at what other people are paying for similar companies. As one of my professors said, \"Someday, someone will pay you a lot of money for advice. And your advice will be, 'do what everyone else is doing.'\" Basically you look at a multiple of trading price or purchase price to revenue or profit, and use that multiple to create a value for your own company. EPS: EPS is net income per share. Not necessarily directly related to value, but often times markets will value a company based on predicted EPS, so if it goes over or under, the value will shift.",
"It's really simple. You take the number of outstanding shares, which for publicly-traded companies is a matter of record, and multiply it by the current share price. This gives a statistic called *market capitalization,* which is what you're looking for."
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78yzjn | What is Cognitive Psychology? | Question says it all. I know there is another question that explains it (along with a few other forms of cognitive sciences), but I still don't understand what Cog Psych can be used for. As a bonus can someone also please explain Behavioral neuroscience? Thanks! | Other | explainlikeimfive | {
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"Psych final year student here. Cognitive Psychology is a study of how our brain perceive and make sense of the world. It studies anything from how our senses receive input from the outside to how our brain processes these inputs. Let me give you a brief overview of some prominent topics. First we have attention, how our senses attend to so many stimuli in our surroundings, and how we choose what to attend to and what to ignore, theories like salience (information that stands out) and visual field (what we are focusing on) applies here. There is also the perception of faces, why we are able to recognize faces and how it is done. Do we perceive the face as a whole? Or do we separate the whole face into features and interpret it that way. We not only try to explain these theories psychologically, but on a neural basis as well using FMRI and PET scan and such devices, but you could argue that that is more in the field of neuropsychology, but I digress. Other than seeing things, we also study about hearing, touching etc., and it isn't just limited to the basic \"how each sense work\", we also study things like how we combine different sensory inputs and so on. Edit: for some reason, I missed a lot of the important topics, probably because those were the focus of my research, so let me add to that. There is also memory. It can be as simple as how memory works (encoding, storage, retrieval) to the different memory processing methods in short and long term memory, to even the study of different kinds of memories. There is language. The study of language acquisition, bilingualism. You can think of topics like people who know two languages have an easier time of learning a third one. And then there are also decision making, reasoning. I think you sort of get the point. And the end, ideally we would connect all these topics and that gives us an understanding of how we perceive our world.",
"I studied this and related topics in university. It's the study of how the human mind handles information, learning, memory, thinking, problem solving, etc. This is different from other branches of psychology that focus on emotional issues, child development, disorders & abnormalities, or other issues. Cognitive Psych is used to understand how people think, so that we can design situations and jobs to be understandable, and to avoid mistakes. It's also used by artificial intelligence professionals to get ideas for how thinking might be done."
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78zd5y | What causes that unique smell of snow? | Searched and I found some similar questions but not the question I was looking for. Why is it that when it's snowing there's such a distinct smell in the air? Why does snow smell and taste different from water? | Chemistry | explainlikeimfive | {
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"Cold air dampens your sense of smell because it numbs the scent receptors in your nose. Also, similar to rainfall the water has been cycled from source to cloud to destination so it is fresh and not stagnant like a pond could be. Static water goes off due to external chemicals leeching into the water and contaminating it. So what you are smelling is true H2O. Similar to if you burn your tongue food tastes different."
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78zpw4 | Does the American president have much power, or are they basically a figure head to focus on? | Other | explainlikeimfive | {
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"The US President has total control of the executive branch of government. That's the military, law enforcement, regulatory agencies, and the intelligence apparatus. He's their boss, they do what he tells them. Congress (composed of the House of Representatives and US Senate) controls all government funding. They can check the President's power by refusing to pay for what he wants to do. They can also remove the President from office through impeachment proceedings. The judicial system, headed by the US Supreme Court, checks both Congress and the President by being the ultimate arbiter of the law. The court decides the legal extent of the powers available to the other branches of the government.",
"> Does the American president have much power? Yes the wield quite a bit of power, and have disproportionately more power than any other 1 person in the U.S government. However, They have much less power than most U.S citizens would like to admit. They appoint a people to a lot of government agencies as well as to the supreme court only needing congress approval. They also are in charge of the largest military in the world and can use it mostly as they see fit. An actual war needs to be signed off on by congress, but after the declaration is made military action is decided by the president. They are also in charge of the enforcement of all federal laws, which covers a lot. Things like the FBI, DEA, CIA, Homeland security all fall under control of the president."
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7907m5 | difference between C++ , C# and Java | Technology | explainlikeimfive | {
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"I'm primarily an Embedded C and Python programmer, so please take this into account when reading this. I do have experience with C++ and Java, and just a tad in C#. This is meant to be an overview, and I'm open to suggestions from programmers with more experience. To explain the differences, we first need to address the main similarity: * All 3 are object oriented languages. Now, the differences: **Portability**: * Java was created to be easily portable between systems. In theory, code that works on a Mac will work on Windows, Linux and any other supported systems. This is not completely true, but at least it makes portability easier. [Note: this applies to Java SE, there are other versions where this might not apply]. * C# is mostly used for Windows, since it was designed by Microsoft. * C++ is in the middle. You can create a portable program as long as you don't use any specific functionalities (not easy if you have a GUI) and a compiler that works for different systems (also hard). * C++ and C# are \"descendants\" of C, and share several things with it, like syntax. Java is it's own platform, and has a (somewhat) different syntax and its own file extensions. **Compilation**: * C++ and C# programs need to be compiled before they can be executed. And there are different compilers available, each with its flaws and strengths. * Java does have to compile too, but the output is a \"plataform-neutral\" byte-code that is then run through an interpreter. This is what allows Java to be easily portable. The interpreter takes care of the specifics. * C# is compiled into byte-code too (called MSIL). **Efficiency & Resource Management**: * C++ is the most \"barebones\" of the three, it does not as much functionalities by default, and tends to consume less resources. The downside is that you'll have to spend more time coding. * C# and Java have garbage collection built into them. C++ does not. This is a really simplified explanation, I hope it's useful though! EDIT: better explanation of C#/Java byte-code.",
"They are all object-oriented descendants of C. C++ came first and compatibility with the C environment is both a feature and limitation. Typically it's compiled fully into local machine code. The early compilers just translated C++ to C. Java has C-like syntax but has much less in common under the hood. In particular, it was designed with portability in mind and so it's almost always compiled to byte-code which is then interpreted. C# is what happened when Microsoft failed (for legal reasons) to embrace and extend Java. That's a somewhat cynical view but C# is pretty definitely a Java descendant, learning from people's experiences with Java and adding improvements."
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790dq5 | Can someone please explain the Banach–Tarski paradox | Physics | explainlikeimfive | {
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"Rather importantly, this is not a paradox in *physics* but in *mathematics*. It applies to idealized mathematical objects, not anything that exists in real life. The Banach-Tarski paradox says that you can start with a sphere, cut the sphere into 5 pieces, shift and/or rotate each of the 5 pieces (no stretching, bending, rescaling, or adding new points), and glue them back together in such a way that you end up with 2 spheres as a result. This is extraordinarily unintuitive, and as we might expect it comes with a major caveat. Each of the 5 \"pieces\" is an extremely strange set theoretic construction: a scattering of points which doesn't have a well-defined volume. While shifting and rotating an object should preserve the object's volume, if it doesn't have a well-defined volume in the first place then all bets are off and just about anything can happen - including the possibility that if you glue all 5 back together you end up with 2 ordinary solid spheres. On the other hand, if you cut a sphere into any reasonable, physically-possible collection of pieces, the pieces will all have well-defined volumes and the construction fails."
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790u7d | The NASA twin study. I know what it is. Just explain their findings. Like I'm 5. Years old. Thanks. | Physics | explainlikeimfive | {
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"There are a lot of effects on the human body from being in space. Micro gravity affects your muscles and bones, there are weird particles that pass through your body (including your eyes and brain, which cause [strange flashes]( URL_0 )). It's hard to study the long-term effects of being in space, though, because everyone is a little different. Are your bones deteriorating because of the microgravity, or is it because of genetic predisposition for osteoporosis? This is true of any study that attempts to look at long-term effects of something. To account for as many variables as possible the best subjects to use for those studies are twins. Because they're genetically identical, you know that whatever genetic predispositions they have will affect both. So in this case, if they *both* get weaker bones, you know that it's not *just* the microgravity. But if one gets weaker bones and the other doesn't, then you know it's something to do with being in space (or not, as the case may be). However, with astronauts you have another problem: you can't just take a random twin and put them in space. You need a *lot* of specialized training to be an astronaut, obviously. And you can't even just train one. The rigorous training and strictly controlled diet of astronauts are variables that could affect the outcomes of the study. This astronaut has stronger bones than his non-astronaut twin, but is that because of his diet that includes a lot of calcium, or strength training that went into being an astronaut? Conveniently, NASA has one set of twin brothers that are both astronauts! They've both had very similar experiences as part of NASA. One is spending a year on the ISS, the other is staying on the ground but also getting the same diet and exercise regimen - basically as much as they can keep the same with him on the ground. They'll study the differences between the two astronauts to study long-term effects of being in space. This is an important study because going to Mars would require longer space missions than we've done in the past. No one has stayed in space that long, really, and we haven't had good opportunities to study them and the effects of that. So they're doing this study to better understand what we need to prepare our astronauts for if we're going to successfully send a team to Mars.",
"I'm reading Scott Kelly's book (*Endurance*) now, about his time in space. He's the twin who spent a lot of time in space at the ISS--recently spent a year, previously spent months at a time, including a 6-month stretch some years ago. Mark Kelly is the twin who has stayed on earth. While he's flown 4 space shuttle missions, they were each around a week long only. He's married to Gabby Giffords and brother Scott was in space when Giffords was shot. Anyway, in addition to /u/RhynoD 's great answer, I'll add that there hasn't been a lot of data yet. So far they've seen that Scott has lost bone mass and muscle strength. He got taller in space due to lack of gravity compressing him, but within a few days he went back to same height as Mark. He suffered a lot of issues re-adjusting to gravity when he came back, such as blood pooling in his legs, rashes kind of like bedsores, and some vision problems. Those are the acute differences, and after a period of adjustment they tend to go away. So now they're looking at long-term differences, and that will take time to assess. So those findings are pending over time. For example, being in space increases your risk of cancer. Both twins got prostate cancer at the same young age--mid-40s. But only time will tell if Scott's heart was permanently damaged, or if his bone loss is going to be serious as he gets older, etc."
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790ya0 | What happens to a charger that's plugged into a power outlet but doesn't have a device attached? | For example, if I plug in the power brick for my computer into a power socket, but I don't attached the charger to my computer. What happens to the brick while it's on "idle?" Is it somehow being damaged by me leaving it in the power outlet while I'm not using it? Edit: Welp, I finally understand what everyone means by 'RIP Inbox.' Though, quite a few of you have done a great job explaining things, so I appreciate that. | Technology | explainlikeimfive | {
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"Wall adapters and chargers are almost always AC to DC adapters. What they do is take the electricity in the wall and change it from whatever periodically-changing voltage is standard in your country (AC) into a constant voltage (DC) of a certain amount. A simple way to do this is to change the voltage with a transformer and then force it to always move in the same direction. A more complicated (but more efficient) way to do this is to store it as a magnetic field for a very small fraction of a second and then bring it back as the correct voltage. In either case, the final voltage is regulated by capacitors which store energy and try to keep the voltage steady. Well, that's the ELI5 version of it. Anyway, theoretically an AC to DV converter circuit shouldn't draw any energy out of the capacitors which keep the voltage steady when there's nothing plugged into it, but in reality it's not so simple. The components that make up the circuit are imperfect which means it will always use a little bit of energy when plugged in. In addition, many power bricks have a LED on them which shows that it's plugged in, meaning that you always have some tangible amount of power being used. TL;DR: It will always use a small amount of power when plugged in, but you won't harm the adapter by doing so.",
"Not much. It does draw a minimal current, but it's neglible. It won't affect the lifespan in a meaningful way (the charger is probably one of the last components in the computer to die anyway...). So, don't worry about it.",
"Why does my power brick make a high-pitched noise when my phone is fully charged, but still connected to the charger? Edit: I'm not a native speaker, sorry. Thanks for your corrections: my phone charger is not a \"power brick\".",
"Typical non-english disclaimer: sorry for destroying your language; I am french Canadian. Edit: In this example, I am referring to a 5V usb cellphone charger. However, this applies to most [chargers]( URL_0 ). A wall charger is basically three components (before someone start to bash on me, I understand modern switching setup may have different designs, but understand this is ELI5). & nbsp; 1. A step down converter (convert 100-240V to something like 7-9V) 2. A AC-DC converter (Wall electricity to battery like electricity) 3. A regulator & nbsp; So, you have 3 components, with different roles that work together. Electricity coming from the wall (also called \"Main\") has to be converted from its original state, which is \"vibrating\" at 50-60 hertz and could be anywhere from 100V to 260V (main is actually not regulated, so it may vary a little during the day, and depending the area you are). To give you a rough idea what 60hz is, it's the ZZZZZZZZZZZZZZZZZ sound an old neon makes. & nbsp; It is much easier to work with smaller voltages than high voltages, specially when confined in the small area of a wall charger. Since we want to end with low voltage, we start that way to simplify the rest of the circuit. That is the job of the step down converter. & nbsp; Once the step down converter has lowered the voltage to something, say, 7-9 volts, we want to turn the AC (vibrating) electricity to DC (continuous). This is usually done by a single inexpensive part. & nbsp; Once we have low voltage DC power, we simply need to regulate it. This is where the regulator comes in. The job of this part is to control the flow of electricity in order to maintain a constant voltage (5V in our case) across load. This means that regardless if your phone is connected or not, the output of the wall charger will \"always\" be 5V. & nbsp; So, to answer your question, if you leave your charger disconnected, your regulator simply keep a 5V on it, wasting a ridiculously tiny amount of electricity (1-5 cent a year depending the pricing of electricity in your area). Some smart chargers may have a sleep mode, turning themselves off completely unless connected. Regardless, a properly designed wall charger will never suffer any damage from staying disconnected. & nbsp; Some people have asked what was the whistle that could be heard when the phone was full or disconnected from the charger. This is what we call \"coil whine\". Basically, a switching regulator works by pulsing electricity through a coil, which create an magnetic field. Under very low load, the pulse becomes \"slower\" (simplified), which makes the coil vibrate in a frequency we can hear. High quality manifacturers will fix that by gluing the coil during assembly, or using a higher frequency regulator. Regardless, this is not an indicative of a failing device, you can still use it without any issue. BTW, this is my first comment on ELI5, I hope it's clear enough.",
"Wall chargers are like a good woman. Think of a man as the device you plug in (resistance). The more attractive men find her (voltage) the more men (current) she will attract. The more men she attracts (voltage x current) the more power she has (watts). If she is a 10/10 (high voltage) there's a potential that she is going to attract way too many men (current). Being able to attract that many men is too much power (watts) for any one woman to have so she breaks down and cries (overload). Without any men at the bar (resistance) there is no load on the woman (your charger) and subsequent nobody walks up to talk to her (no current). No men flocking over her means she has no power (watts). She's still super attractive (high voltage) though so be careful around her!",
"what about if the charger (without a device) is plugged into a UK wall socket that’s switched to ‘off’? I’ve always wondered what on/off means in the wall socket context",
"Most chargers use transformers. A transformer is kind of like a water wheel. As water (current) flows by, it starts things moving (electrons) which power your device. If the device is unplugged it would be the same as just stopping the wheel. Current will continue to flow past unhindered. Edit: move an r",
"For starters your charger is drawing power from the wall at all times regardless of if your device is attached or not. But the amount is the important part. When you plug in your cell phone or laptop charger there are parts inside (keeping this EL5 as I can) that use AC from the wall and convert them to DC. Your phone/laptop then uses that DC to charge and power it's component. When your device is not attached you are drawing less (much less) power but technically the charger is drawing what we like to call quiescent current current. This quiescent current (or no load input current) is what your asking about. As other people in the comments have posted we are talking less than 5 cents a month. The math is simple and many people here in the comment have explained it well. Take your quiescent current times your input voltage (about 115v in america) and that gives your power. Then multiply that by time. In a perfect world your charger would draw zero power when plugged in, but due to the imperfections of electrical components and this not being a perfect world....you know. With regards to safety, and things of that nature, that's a nother conversation to be had. Edit: regarding damage, technically you are \"damaging\" your power brick when it's plugged in. But we are talking damage that takes years. By plugging in your power brick your using it which reduces it's life time, but this can be said about any electrical components in existence. More likely than not the designer of your power brick took the time to evaluate the details here. All and all your not going to destroyed your power brick sooner by leaving it plugged in. This how ever is not true for things like batteries and is another conversation in it's self. Edit: Tldr: your charger draws a tiny amount of power when you plug it in the wall with nothing on the other end. Your power brick won't die on you just cause you leave it in the wall all year.",
"Your wall power will be brought in to the converter, pass through a step down transformer, rectified using a bridge rectifier, filtered and the resulting DC voltage will be regulated to 5vdc then stored in the output capacitor. The resulting power is potential. If there is no current draw the unit will not be using the power, it just sits there at the ready. No harm is being done at this point. The components are barely working until current is pulled. But there is usually a led installed on these power bricks which will pull come current. Negligible amounts but some all the same. Source: work on magic",
"Mine makes a ticking sound while no devices are attached, so in the \"idle\" state still there is electricity going through it's circuit. Not a pro here, but probably that electricity going through it's components it will eventually reduce the lifespan of the charger."
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790yc1 | How do city planners pick streets to be one ways? | Other | explainlikeimfive | {
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"One-way streets allow for faster traffic and higher capacity because there is less interaction between cars--such interactions are always a source of slow-down and potential collisions. It also means the second lane could be specialized, such as being for buses only. In a typical North American city grid, a planner might decide to make all streets of a certain width one-way streets. They'll alternate so that all even streets go one way, all odd streets go the other. It gets more complex if you don't have symmetry or if traffic flows aren't expected to be the same in both directions."
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7914q7 | What exactly happens to the body to fall into a medically induce coma? | Also, how does a medically induced coma differ from one that is the body’s natural reaction to trauma? | Biology | explainlikeimfive | {
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"From an ER doc: We put people into \"medically induced comas\" to basically protect their airway. If, for whatever reason, a patient is unable to breathe on their own, we intubate them (put a tube down into their lungs) to breathe for them, but also give them medications to sedate them, so as not to torture the patient by keeping them awake while we are trying to stabilize them. This process can take hours, days, weeks, or even can be permanent. For example, someone has a brain bleed, which causes such an increase of pressure within the head that it is squeezing the brain so tight that parts of the brain lose bloodflow and become compromised. The patient rapidly loses function of several aspects of their bodily function. In thecase of trauma, we rate them on the Glasgow Coma Scale (GCS). At a certain level, patient's are almost guaranteed to continue to decline to the point that they will die unless they are sedated and intubated. And thus, what are considered medically induced comas start out like this. Whether its an unstoppable seizure, a massive heart attack, a stroke, etc. some catastrophies to the body and brain are so severe that patients must be sedated in order for doctors to initiate critical care. If the patient were not sedated, they would likely lie there awake but unable to move or talk, while needles and mechanical objects and medicines are being pumped into their bodies. The \"medically induced coma\" is there to sedate the patient until doctors can stabilize whatever issue is causing them to be so sick, if even possible."
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79193w | Difference between grad school, masters and phD? | Other | explainlikeimfive | {
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"Grad school (short for \"postgraduate school\") is what you call it when you keep attending university after earning a bachelor's degree. If you attend grad school for a while, you can earn a Master's degree. If you stay longer, and do significant original research, you might earn a Doctor of Philosophy (Ph.D.) degree."
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791d1d | How does anaesthesia work in making us quell pain? Does the body stop recognising pain? | Biology | explainlikeimfive | {
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"It blocks the transmission of certain chemicals from one nerve cell to the next, so that the pain message (transmitted over a series of nerves) never reaches its destination.",
"I'll give it a try using lidocaine as an example: Think of nerves as wires with sodium powered generators attached to them. These generators have no Sodium fuel tank and instead rely on taking in sodium as needed from their surroundings through channels (holes, whatever). When lidocaine is injected into the area of these nerves, it essentially pollutes the nerves surroundings with lidocaine. This lidocaine is then sucked into the generators where it blocks the channels from the inside. With these channels blocked, the generator can no longer get fuel to generate electricity. Thus no electric signal is transmitted to your brain to produce a pain response. This is a really dumbed down version. In reality nerves are much more complex than this model and there are multiple different pathways depending on the type of anesthetic used.",
"Anesthesia has 3 parts: anesthetic (for pain), paralytic (to keep you from moving or having a reflexive movement), and a narcotic (to keep you asleep). Broadly sums it up.",
"Anaesthesia is a combination of analgesia (controlling pain either with blocking nerves using local anaesthetic or central action using pain killers like opiates), hypnosis (making sure the brain doesn’t remember - usually by inducing sleep) and paralysis (so surgery is possible). The combination of these things can be tailored to the specific situation. If you are having a simple surface operation (such as wound suturing) then it can be done with mostly analgesia like local anaesthetic. If you are having a more involved procedure such as an appendicectomy then you need all three components. If you induce hypnosis and paralysis the body still react to pain (increased heart rate, blood pressure etc but you don’t remember it nor move to it). It can be quite important to carefully monitor these these things if the patient is paralysed to prevent awareness ( imagine paralysis alone without hypnosis or analgesia). Some procedures like gastroscope (camera into the stomach etc) can be performed with a hypnotic agent alone that doesn’t induce sleep but does prevent memory formation so you don’t remember the unpleasant bits (such as benzodiazepines). TLDR: anaesthesia is uses one or more of hypnosis, analgesia and paralysis which is appropriate to the procedure being performed."
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791gqp | Why do windows reflect better when it's dark outside? | Physics | explainlikeimfive | {
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"They don't actually reflect better. The difference is that there is far less light coming from outside so you can see the reflected light from inside more easily. It is the same sort of idea behind how you can see stars at night but not during the day; they don't stop shining, there is just other light overpowering them."
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791mnz | Who decides how much the president earns? | Economics | explainlikeimfive | {
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"Assuming you mean the US President, the Constitution includes this provision in Article 2: > The President shall, at stated Times, receive for his Services, a Compensation, which shall neither be increased nor diminished during the Period for which he shall have been elected, and he shall not receive within that Period any other Emolument from the United States, or any of them. The exact form of the presidential Compensation is set by Congress by law. Presently [US Code Title 3 Chapter 2 § 102]( URL_0 ) sets it at a $400 000 yearly salary to be paid in monthly installments, and a $50 000 expense account for private expenses while carrying out the duties of the office."
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791ns9 | Why is digital storage getting better every year? | How is it that 15-20 years ago, I had to save up for a month in order to buy a 1GB Hard Drive that weighed over a kilogram, when I can now find microSD cards with 400GB capacity? Is there a limit to how compact these things can get? Will I be walking around with thousands of terabytes in my pocket within the next decade? | Technology | explainlikeimfive | {
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"Technology is refined, step by step. Moore's law applies pretty well to storage, so expect a doubling in capacity every 18 months. Is there a limit? Sure there is (storing a bit requires at least one electron, with current scientific knowledge), but we aren't close to it yet."
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791pno | SSD's. If I have a 100 GigaByte SSD, does that mean there are (roughly) 800.000.000.000, or 800 billion transistors inside of the SSD for storing data? | I'm trying to figure out how SSD's work. Just to explain my numbers: * 1 byte is 8 bits. * 1 gigabyte is 1 billion bytes which is 8 billion bits. * 100 gigabytes would be 800 billion bits. Or do I have this completely wrong? Like as far as I understand, an SSD has a bunch of transistors which can either be 0 or 1, and that's how they store data. | Technology | explainlikeimfive | {
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"6 transistors per bit in an SSD, so, in your case, 4800 billion transistors. It's actually quite impressive, it's over 500 times as many transistors as there are people on earth.",
"More actually, a transistor in itself doesn't store any data. A quick googling tells me there are typically 6 transistors used to store a bit. I am not the one to explain to you how they need to be arranged to actually store memory though, hopefully someone else can fill in on that part... There are also different technologies, IIRC the cheaper ones use an MLP technology, which means multiple voltage levels can be stored, to each set stores 2 bits but requires double measurements to read the bits, that probably changes the number of transistors per bit.."
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7926kc | What is the difference between ketchup and tomato sauce? | Other | explainlikeimfive | {
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"text": [
"Ketchup usually contains additional ingredients such as sugar, vinegar, seasonings (salt, garlic, pepper, cloves, etc.) Although tomato sauce can have more ingredients... at its most basic form it is simply tomatoes cooked down with a bit of lemon juice, vinegar or salt. Both forms require a long cooking time to reduce the tomato to a soft sauce-like form.",
"Ketchup is only ever ketchup: that sugary vinegary tomatoey red goop they sell in bottles at the store. Tomato sauce could be used to describe a whole range of tomato based sauces. Ketchup is a sauce made of tomatoes, so it is a tomato sauce, but there are other tomato sauces that are not ketchup. I'd say Heinz baked beans come in a tomato sauce, but they certainly don't come in ketchup."
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792g3y | What is Ice 7? | I was just watching random videos on YouTube, and I stumbled onto a video about strange planets. The narrator mentioned a planet who's ocean floor was made of Ice 7, but couldn't explain what it was. Now I'm curious on what ice 5 is and what are its physical properties. Video Link: URL_0 | Physics | explainlikeimfive | {
"a_id": [
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"text": [
"It is just a different geometric packing of water molecules into a solid. Water packs differently depending on the temperature and pressure that it is under. Take a look [here]( URL_0 ) to see all the known phases.",
"Ice is what happens when water gets cold and settles into a crystal structure. At different temperature/pressure levels, it forms a different shape of crystal. They're interesting to chemists because it does different things but that's about it.",
"Good answers here; just to mention one very important property of high-pressure ice phases: ordinary ice floats on water, but these kinds of ice sink."
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792n9k | Why has Hdr been so common in cameras for so long but is only now beginning to move into mainstream TVs, Smartphones and games consoles? | Technology | explainlikeimfive | {
"a_id": [
"doyoch1",
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"text": [
"They're different technologies. The HDR in cameras involves taking two shots at high/low exposure, then merging them to a single photo. The HDR in video displays refers to the ability to show a wide range of brightness.",
"HDR-photos are typically just composite images of several photos, taken with different exposures. What proper HDR is about, is being able display/capture truely dark and really bright parts of the image, both at the same time. This is what's new, and it's not easy."
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792owe | What is WACC and why is it important? | Economics | explainlikeimfive | {
"a_id": [
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"text": [
"Weighted Average Cost Of Capital. All sources of capital, including common stock, preferred stock, bonds and any other long-term debt, are included in a WACC calculation. It is important bc it determines how much interest a company owes for each dollar it finances. Also WACC is an investor’s opportunity cost of taking on the risk of investing money in a company. Long story short, google to learn more. It's very complicated question.",
"The idea here is that when a business has money, that money isn't \"free\" - the business has either taken out loans for that money (which have interest rates that have to be paid back) or has gotten that money from investors (that expect returns on their investment). Every dollar a business has has to be earning money so that you can pay back those two groups what they expect to be paid back for letting you have capital. The WACC is the _average_ cost of a dollar when you factor in how much is funded by debt and how much is funded by investors."
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792qqr | It seems clear that subatomic particles aren't solid little spheres, what are they? | Physics | explainlikeimfive | {
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"text": [
"Bear with me, physicists, this is super ELI5... Subatomic particles are both an infinitely-small dot, and a spread-out fuzzy cloud representing the chances that this dot will be seen at any given location. But that gives the wrong idea that the dot is the real particle, and the cloud is just a description of it. But in every sense that matters, the \"cloud of maybe\" *is* the particle. Yes this is deeply weird.",
"The current physical model treats elementary particles as 0-dimensional points. We do not know if this is what they truly are, but the math works out. String Theory is a hypothesis that suggests they may be dimensional strings instead of points, but we lack the ability to test this experimentally.",
"To add to what others have said here, They’re not really anything. They’re points on their corresponding field. The particles themselves aren’t a thing. One way a professor explained it to me is that saying you have the same electron in your body that Einstein had in his brain when he discovered relativity is like saying you sign your name with the same J John Hancock used to sign the Declaration of Independence",
"Pilot wave mechanics (De Broglie-Bohm) is probably the best intuitive model of subatomic particles. A particle is a pair of things. It is a 3D wave in the electromagnetic-weak field and a little solid sphere (but like infinitely small) that bounces up and down in that wave getting led around by the wavefront. Here is a video that should make everything more intuitive: URL_0 🎥 Is This What Quantum Mechanics Looks Like? - YouTube"
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792td3 | How do people that live off Patreon/Youtube/Twitch pay taxes? | Economics | explainlikeimfive | {
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"text": [
"The same as any other self employed person. Schedule C and Schedule SE i believe are the 2 forms besides your 1040. Also paying in quarterly avoids some fees. I guess the ELI5 version would be that you tell the Govt how much you made and pay taxes accordingly",
"So you're confusing the process of paying taxes, with the process of withholding tax from each paycheque. Many people are confused here, but the distinction is important. During tax filing time (April in Canada, I think it's April in the US as well). Everyone needs to fill out a tax return. That tax return calculates the exact amount of taxes that you owe for the year. This is your \"real\" tax liability. For most employed people, their employer has been sending small withholding payments to the government with every paycheque. These are based on an ESTIMATE of what your real tax liability will be. Once you complete your tax return in April, it compares the total withholdings estimate you've already paid vs the actual tax liability. This sometimes results in a tax refund. That happens when the estimate was too high, so the government gives you back some money that they should never have been paid. Other times you have to pay a little more. This happens because sending people HUGE bills every April creates a collection nightmare. Imagine if you earned $40,000 per year and got a bill for $15,000 every April. That would suck hard. So instead the government enforces everyone to pay installments. But this process of withholdings. It only applies to people who earn income from employment. People who are self-employed are not subject to these rules. So if you are self-employed, you do the same as an employed person. You file a tax return at the normal time. Your withholdings are $0 so you always owe, then you cut the government a cheque. You can pay installments and might even be required to, but they don't come off your paycheque because you don't get a paycheque. Rather you just cut a cheque to the government every month (or every 3 months)."
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792v8e | Why does cordial/concentrate fall to the bottom of a full glass of water yet saturate the water if already in the glass prior to adding water? | Physics | explainlikeimfive | {
"a_id": [
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"text": [
"Cordial is denser than water, but can be dissolved in water and/or exist in suspension within it. When you pour water into a small amount of cordial, the agitation caused by the water being added results in it being mixed effectively, resulting in dissolving or suspension of the cordial. If you tip cordial into water, there is far less agitation, and the cordial sinks to the bottom because it is not being dissolved or suspended, and is denser than the water it's put in."
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7932me | How do Youtubers that make "movie mistakes" videos monetize their videos? Aren't they using someone else's creation to make money without their permission? | Technology | explainlikeimfive | {
"a_id": [
"doypga5"
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"text": [
"In the US there is a \"fair use\" doctrine which allows the quoting or in this case inclusion of copywritten material for such purposes as criticism. Typically this would be used for things like reviews but a \"movie mistakes\" video still falls squarely under the category of criticism and therefore fair use."
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13
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7933cs | If a rainbow is made from light refracting on raindrops, why do we only see one static rainbow instead of multiple rainbows moving fast? | Physics | explainlikeimfive | {
"a_id": [
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"text": [
"A given color of the rainbow is only seen from a particular angle from any given droplet of water. As a particular droplet moves it it either will direct a different color toward the viewer or nothing at all. The result is that a particular patch of the sky will appear one color while it is in fact made up of many moving droplets at any given time. Each droplet is refracting many colors but over a variety of angles, and you only have eyes in one location.",
"Because you only see the rainbow when your eye, the sun, and the droplets are at a very specific angle. Once the droplets move, they are no longer at the correct angle, while new droplets move in to replace them."
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7937vg | Why are injuries more painful when you're cold? | Biology | explainlikeimfive | {
"a_id": [
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"text": [
"Ok so we're talking about different \"perceptions\" that are grouped in to the sense of Touch. There are a few - temperature, texture, pain etc. They all have different nerves associated to them in different layers of the skin or attached to hair follicles and are triggered in different ways. How is not important. Generally the more extreme the effect, the greater the response you experience. This is because each nerve-end has a different threshold it requires to \"fire\". So the more extreme the effect the higher the number of nerves-ends are fired at the same time. Now when you are cold (or hot) you have more nerves being triggered at once by different simuli at the site of injury, above your \"comfort\" range, and thus the brain perceives the input greater than it actually is; because those senses are similar AND coming from the same place... your cold AND painful toe. In essence your brain is misreading the signals because it's getting more information than it's normally used to."
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793ij3 | What are the effects of an explosion's shock wave on the human body? | You always see ring of shock wave coming off explosions in videos. What effects do they have at a long range on your body? [Shockwave]( URL_0 ) Edit: Added the Shock wave that peaked my interest. | Biology | explainlikeimfive | {
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"The main dangers of a shockwave is that it can burst blood vessels in your lungs and you can drown. This depends on the size of the explosion and the medium. Shockwaves through air have to be very powerful, to the point that it's the blast you care about and not the shockwave. If a shockwave traveling through water hits you while in water, that could be deadly at lower scales. Mythbusters did a couple of episodes on it. Exploding TNT/ANFO right on the surface of a lake to determine if you could safely escape by jumping in the water. You had to swim either very far or very deep to get away alive. I don't remember the distances off hand but that is going to vary with the type of explosion anyway.",
"10 psi of over pressure will kill you with heart and lung damage, also strong enough to rip off limbs. 4 psi of over pressure damages lungs, ears, etc and other internal organs. Fatalities are likely. 2 psi injuries are less severe but the damage can still kill you. Those pressure may not seem like much. But think of your thigh. Say it's 16 inches long by 8 inches wide. That's 128 square inches of surface facing the blast. At 10 psi over pressure your exposing one side of your leg to 1,280 lbs of total force. That's only a small portion of your body experiencing that. Add in the total surface are facing the blast and there is tons of force by just a small pressure wave like 10 psi. Also, because over pressure is a traveling wave it won't apply force equally to the front and back of your leg, which is why it's so dangerous."
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794aep | Why do CRT TV's use so much more power than the normal TV's of today? | Technology | explainlikeimfive | {
"a_id": [
"doz0iip"
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"text": [
"The way they draw the image is kind of crazy. The emit a powerful beam of electrons from a device called a cathode, and then use powerful electromagnets to steer this beam all over the phosphor-coated glass screen, making various points glow with energy. That takes a lot of power."
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794d7y | how does Redshift work? (the astronomical phenomenon) | Physics | explainlikeimfive | {
"a_id": [
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"text": [
"Have you ever heard a train horn or siren get higher-pitched as it approached then lower-pitched as it went by? Well, that's the Doppler effect. What's happening there is that the sound gets compressed, making it sound higher-pitched, as the thing making it moves towards you and stretching the sound, making it sound lower-pitched, as it moves away. I found a [cute little animation on Wikipedia here.]( URL_0 ) Light works the same way, but it turns bluer when compressed and redder when stretched. Since the universe is still expanding, literally everything is moving away from everything else at high speed, stretching the light it gives off, making it appear redder. That stretch is called redshift."
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|
794dhp | How does the Earth create a magnetic field? | Additionally, why is the magnetic north different from the true north? Why does the poles of our Earth's magnetic field also happen to be at its geographic poles? I know this sounds stupid, but why not at the east and west instead of the north and south? | Physics | explainlikeimfive | {
"a_id": [
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"text": [
"We're not 100% positive, but the best known theory right now is the \"dynamo theory\". The outer core of the planet is liquid and is in constant motion as convection currents move heat around. It's this motion that creates the magnetic field. The magnetic poles wander because the flow inside the core isn't 100% consistent all the time. The flow patterns change as the temperature differential changes. That flow pattern change is what causes the poles to wander and fluctuate.",
"Ever pour cold milk into a cup of warm coffee? It stirs itself. The center of the earth is warm. Warmer than the surface. This means the there are currents of warm molten conductive iron moving from near the core toward the surface. When it gets to the surface it cools and false back down. You get a loop going. Since the earth is spinning, the molten currents near the equater tend to form currents going east to west rather than north south. It's a lot like the Coriolis effects you see in hurricanes. Near the poles, it can orientation itself any which way and there isn't really a preference. The oriented currents near the equator govern the majority of the magnetic field because they get aligned and magnetically drive the ones near the poles. *** Moving electrically conductive materials generate magnetic fields in a really interesting way. It's actually based in special relativity. As the electrons move, the undergo length contraction - a relativistic change in apparent length due to the speed of light being fixed. This leads to an apparent imbalance in the electric field between otherwise balanced electrons and protons. There is an electric repulsion in directions at a right angle to the direction of electron flow. If those electrons flow in a circle as in a swirling current, you get aagnetic pole according to the right hand rule."
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794wkz | what is a hot spot after a fire, and why does it last for hours after the fire has been put out with cold water? | Chemistry | explainlikeimfive | {
"a_id": [
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"text": [
"Hot spots are small pockets of fire that are hidden or protected from the main deluge of water or other fire suppression. They continue to smolder or burn quietly until they finally burn out or reignite the rest of the fuel. They're usually found in some small, hidden away log or deeply charred piece of framework. Before fire crews carried thermal cameras or even point-source thermometers, it was not uncommon to have to get called back out to a house fire that had re-ignited sometime during the night. Hotspots can also cause range/brush fires to reignite if the winds pick up after a fire has been thought to have been extinguished or contained. And it never failed that they would relight at about 3am after I'd gotten back home from the fire scene, showered, and was just about asleep."
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794yfw | Difference between RFID and NFC tags | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"NFC is kind of a subset of RFID. RFID - Radio Frequency IDentification is just a means of communication with small devices. It's usually referred to when talking about RFID tags with unique serial numbers that you can use to track items, vehicles, people, or animals. There are active forms of RFID, but they're fairly rare as compared to something like an RFID tag for a cow that you can read as the cow enter the chute to the market truck. NFC - Near Field Communications. A specific method of communicating at a particular frequency over a very short range (20cm is the specification). NFC allows two-way communications between the devices, but doesn't require it. If you wanted to put an NFC tag on a cow, you'd have to have a reader that got right next to the cow's ear versus having an RFID reader that can read it from 5 feet away."
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|
795hvd | Fingerprint scanner (Touch ID) hashing | Specifically, explain it like I completely understand hashing. I understand that when you change the input to a hash function a tiny amount the entire output changes. This is what I don't get: if a hash of the fingerprint is stored then doesn't a tiny variation on the positioning, lighting etc of the scan completely change the output which is then compared with the stored version, thus marking it as incorrect??? | Technology | explainlikeimfive | {
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"text": [
"URL_0 > The raster scan is temporarily stored in encrypted memory within the Secure Enclave while being vectorized for analysis, and then it’s discarded. The analysis utilizes subdermal ridge flow angle mapping, which is a lossy process that discards minutia data that would be required to reconstruct the user’s actual fingerprint. The resulting map of nodes is stored without any identity information in an encrypted format I think the idea is that it's always just looking for the same set of nodes (or rather the subset that is in contact with the sensor during a given scan). Each individual scan may be slightly different, but it's discarding all of the stuff that varies and just looking for a few static parts.",
"Your fingerprints contain a lot of little details that make them unique, that's how we're able to consistently identify different people using them. These details are called minutiae. When the scanner picks up your print, it identifies the various minutiae and can use those to create a consistent hash. Most computer fingerprint systems will do this by comparing the presented fingerprint against a database of fingerprints, but in order to maintain security, a biometric security system shouldn't do that, instead a minutiae point called the pattern, the overall shape of the fingerprint, can be used to indentify the center and rough orientation of the print, from there the computer can then check the other minutiae points relative to that center to calculate the hash and ask the computer to compare the two."
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795jig | Why is it that a liquid that is hot will cool if you whisk it a lot but a cold liquid will heat if you whisk it a lot? | Physics | explainlikeimfive | {
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"text": [
"Okay, so “heat” is molecular movement. If something is really hot, the molecules in that thing are moving really fast. In liquids, heat is the movement of molecules and in solids it’s the buzzing around of molecules. So, imagine you have a spoon at room temperature and a liquid that is boiling. The molecules in the liquid are moving super fast, while the ones in the spoon are relatively stable. When you start whisking the liquid, you’re effectively exposing “cold” (not moving fast) molecules to fast moving molecules. So, the “hot” molecules hit the cold ones with a high velocity and start to shake them around so they heat up. This causes a transfer of energy from the liquid to the spoon until they reach a stable point. Now, some of this heat is lost to air when the liquid molecules hit the air molecules at the surface. Some of the realllyyyyyy fast molecules literally just fly out of the liquid which also cools it down (like water vapor in boiling water). To answer the “cold liquid, room temperature spoon” question, the process is revered. Now the spoon is “hot” (relative to the liquid). So, *it’s* molecules start hitting up on the colder ones to make them move and “heat up”. The constant swirling also exposes the cold liquid molecules to the relatively hot air at the surface which also contribute to heating up the solution."
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795pdv | How is the Crocodile Dentist mechanically random? | Technology | explainlikeimfive | {
"a_id": [
"dozciwf"
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"text": [
"Imagine a disk with holes under the teeth. The teeth aligned with holes go down. The tooth that doesnt align with a hole triggers the mechanism. Resetting the jaw spins the disc (randomly landing on a new sore tooth)"
],
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7963oj | The differences between Marxism, Leninism, and Stalinism | Economics | explainlikeimfive | {
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"text": [
"**Marxism** is a whole way of looking at history and sociology, as well as an economic system. Marxism expounds a \"materialist\" view of history, claiming that it is a society's productive capacity (ability to make things) and the control over that capacity that determines how society is organized, evolves, succeeds, or fails. Marxism from an economic and socio-political perspective can be (partially) summed up by: - history is defined as class struggle, with the owners of the means of production (factories, resources, etc), which are the fundamental shapers of society (according to the materialist interpretation of history mentioned above) exploit the working classes (the ones who actually produce) - this exploitation takes the form of taking the product of one's labor for someone else (e.g. the owner of the factory makes more money than the workers do) - under a purely \"Maxist\" system, the means of production would be owned by the people who do the producing, organized as a democratic collective that would decide on their own how to use the means of production, and which would collectively reap all of the benefits of that production - Society should be organized in such a way that \"from each according to his ability, to each according to his need\" is achieved. - Humans are fundamentally equal in rights and deeds. - Private ownership of the means of production is to be avoided, but private ownership of other kinds of property is generally okay. Marxism called the final end goal \"Communism\", and the intermediate goal \"Socialism\". It's important to note that classical Marxism viewed the end goal (Communism) as essentially *stateless*. The common conception of Communism as \"totalitarian\" or a \"dictatorship\" is due to how horribly the various Socialist states (the USSR, etc) ended up being, but there's no real place for that in Marxism. **Leninism** is an idea of how to achieve Marxism. There were and are many alternative theories (e.g. Trotskyism, Luxemburgism, Social Democracy...). The common \"Totalitarian\" and \"Communist Party\" tropes of Communism arise from Leninism. Leninism states that the best way to get to Communism is by way of a \"Vanguard Party\" whose membership is open only to workers. Workers, in Leninism, are the sole source of authority because they are the ones who produce things (and, under Marxism, production is the primary shaper of society). Since the \"Vanguard Party\" of Leninism is made up of only workers, and since workers are the sole source of authority, then, by definition (in Leninism), the Vanguard Party is the sole legitimate user of power. So it's important to note that \"Leninism\" and \"Marxism\" are not synonymous. Leninism is just one idea of how to achieve Socialism, not the only way. **Stalinism** is a much less well-defined system that basically boiled down to \"whatever Stalin wanted.\" It had a couple of points that were of more general applicability, mostly related to how Socialism could be established one country at a time rather than all-at-once, plus that industrialization was a critically important goal....but mostly it was a made up term so that Stalin could place himself into the same ranks as Lenin and Marx by having \"his own\" philosophy. You see that today in places like North Korea, where they started out as Marxist-Leninist, then became Marxist-Leninist-Kimilsungist, then just Kimilsungist-Kimjongilist, etc. The Kimisms were mostly just cobbled together philosophies designed to make it appear that the Kim family is in the same philosophical league as Marx. **TL;DR**: Marxism is a philosophical outlook that describes a mechanism of looking at history and sociology, and promotes the idea of Socialism and eventually stateless Communism are nigh-inevitable end states of humanity. Leninism is one of many ideas of how to make that happen. Stalinism is one guy's attempt to make himself sound as if he was as grand a thinker as Marx."
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7966df | Why does the human body produce tears as a result of being sad? | Biology | explainlikeimfive | {
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"text": [
"Tears contain cortisol, a stress hormone. Dump that stuff out through your eyes and you feel better right away.",
"They’re easily visible and cause other visual effects on the face (redness, puffiness, etc) to silently display distress. Crying came about as a quieter way to tell others that they need help, since cries of pain/anguish etc sound like “come finish me off” to nearby predators within earshot.",
"The control center of emotions, called 'lymbic system', has a degree of control over the autonomous nervous system. Crying is controlled by a branch of the autonomous nervous system - the parasympathetic. When you feel sad, the parasympathetic nerve that controls the lacrimal gland is stimulated. So, basically, the brain process that makes you feel sad is directly linked to the mechanism that stimulates the lacrimal gland to produce tears."
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[]
]
} | [
"url"
] | [
"url"
] |
|
796dtg | How does a bone regenerate when you break it? | Biology | explainlikeimfive | {
"a_id": [
"dozjfcm"
],
"text": [
"It's not that it regenerates. But rather that the cells in your body builds new bones between the existing break and they all fuse together. The downfall is... this is enormously taxing on the body to do, and its extremely limited. It also can cause problems as well because its not always on point when growing new bone in the break. It could not make enough causing fragile bones, or it could make too much causing bone spurs. But back more to your question. The cells in your body are capable of identifying what part of your body is missing... this could be skin, muscle, and even bone. Given certain conditions, the cells in your body are able to rebuild or transform into those missing parts. The downfall again, is that it is incredibly taxing on the body. And if need be your body will at times decide its better not to rebuild or replace."
],
"score": [
8
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
|
796mjq | Public Debt is often shown as a share of GDP. Why dont we rather compare Public Debt with Government revenue, since its that money that Repays the debt? | Economics | explainlikeimfive | {
"a_id": [
"dozk1lm"
],
"text": [
"Largely because government revenue is adjustable. If it became important to repay the debt, the government could raise taxes. *But* the limit on what can be taxed is set roughly by GDP."
],
"score": [
11
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
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