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lzsuwt | Cloud-native applications. | Technology | explainlikeimfive | {
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"Depends slightly on context mostly a buzzword. If you see it as a consumer it could mean anything from it doesn't run on your machine to developed specifically for the cloud. In a technology sector (think your a developer, engineer, or operations guy looking for a job) it generally means that it is developed specifically to run in one of the specific cloud environments such as AWS or azure. Less often it will just mean the company doesn't have their own servers but is cloud agnostic ie switching from azure to aws wouldn't be hard, generally this means docker containers."
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lzsxci | What really is Second person view? | I’ve seen first person view, I’ve seen third person view, but never second person. | Other | explainlikeimfive | {
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"2nd person would be literally a second person. If you were talking about a videogame it would be literally the camera following another character in the scene instead of you. Technically mario 64 would be that. Since the whole point of view is always from the lakitu following you, but you control it and it's always acting like a 3rd person camera so it's only technically true. A real one would be a camera that follows some random NPC then you are walking around somewhere in the background.",
"There's a driving video game that did true second person view, it achiced this by having you drive a car being chased by the car you were watching from. Really trippy",
"First person is \"I\", or \"we\". Second person is \"you\". Third person is \"he\", \"she\", or \"they\". A book written in first person, is written as if it were written by one of the characters in the story. A book written in third person is written by as if by a narrator outside of the story. A book written in third person would refer to the reader as the subject of the story, which is uncommon. Second person is common in text based video games. [\"You can't get ye flask!\"]( URL_0 )",
"Second person is like one of those \"choose your own adventure\" books. The Goosebumps Choose-your-own-scare series were really popular in the 90's. I used to cheat and read through all the endings sequentially. A modern implementation is the Black Mirror Bandersnatch episode.",
"From a quick google :-) Basically, **second**\\-**person perspective** is perceiving the **game** world through a character that is not controlled by you, but is often looking at your personal player-character. This camera would presumably be controlled by either a NPC (non-player character) or a fellow gamer.",
"A second person view and third person view in video games have a lot of the same characteristics. In first and third person view you're still the main character controlling the camera just that camera angles are different. In second person view it's basically somebody else is controlling where the camera is. For example latkatu in super Mario 64. Another example might be in red dead redemption 2 with the cinematic horse riding camera.you don't get to decide when the camera changes are where it's going to be that's sort of second person",
"Think of Choose Your Own Adventure, or Zork. Second person - You wake up in a forest. There is dappled sunlight coming through the canopy. To your east you can hear a babbling brook. What do you do? Vs 1st person - I woke up in a forest. I could see sunlight filtered through the canopy above. To my east I could hear a babbling brook. Vs 3rd He woke in a forest. He could see sunlight filtered through the trees. To his east, he heard a babbling brook. 2nd person doesn't get used a lot in fiction in general, but I remember the short story \"Paper Slippers\" being pretty effective."
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lzt806 | If the Ancients (Egyptians, Greek, etc.) figured out so many things about the world, why did it take figuring them out again to give them proper credit? Why wasn’t there progress based on the fact they figured it out? | Technology | explainlikeimfive | {
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"There were progress being made on their discoveries all the time. It was just slow. There is a continuous line of discoveries from the Egyptians, Babylonians, Greek, Romans, Egyptians again, Arabians, Italians and eventually spreading out throughout Europa. So for example a geometry textbook might first mention something the Babylonians figured out before telling you what a Greek philosopher managed to find out that built on this and then go on to what an Arabian philosopher managed to quantify from this and then on to how the Italians invented a standard notation for it. And you have similar stories with any discovery in most fields of science. They took thousands of years to develop with progress being made all the time by whichever empire had the resources to hire philosophers at that time. What happened was that a technique called movable type printing press was developed in Germany at a time when Italian city states rich from trade hired a lot of artists and philosophers. This meant that you no longer had to hire a philosopher to go to the only place that had a big collection of these ancient books to study. They could not quickly copy the books and every little kingdom and city could have their own library. So when a blacksmith wondered if he could improve his workshop by installing some sort of automatic hammer he could go to the local library and look up books of famous Egyptians, Arabians or Italians depicting various different mechanisms that he could build for himself.",
"First of all, \"the Dark Ages\" are an invention by 16th century Italians who had a fetishistic interest in Greco-Roman culture and wanted to feel smarter than their grandparents. Plenty of things were developed during the Dark Ages, including windmills, gunpowder, three-field crop rotation and the Gothic arch. When considering humanity as a whole, progress has been going on pretty much the whole time, it has just been slow, for a lot of reasons. Agriculture. When 90% of people have to work in the fields to keep everyone fed, there aren't very many people with the time, resources and inclination to think smart things. Skills. Literacy has not been a common skill anywhere at any point in history (though it was not as rare as some people would have you believe), and a career in being smart would require you to pick up that skill along with at least one new language, instead of doing something more productive like farming. Access to writing materials. Before the invention of wood-pulp paper, writing materials were expensive. Before the invention or adoption of rag paper, writing materials were expensive as balls. This led to only the bare minimum of things being written down and preserved, and things that were considered self-evident or uninteresting were ignored and therefore lost. Skilled labor: Before the invention of printing, the only way to get a book was to copy it by hand. Before the invention of moveable type, the only way to print a book was to get a good woodcarver to carve an entire page, mirror-flipped, into a block of wood. The amount of skilled labor involved, and the cost of buying said labor, in spreading texts meant the movement of knowledge was slow. Lack of contact. Ideas spread and gain traction through trade and exchange of ideas. Some things that appear in isolated places simply didn't leave. For example, none of the Mayan's advances in astronomy ever made it to Europe, and Americans re-invented oil drilling in the 19th century in a way that had been common in China for almost a millenium. Lack of supporting technology. A lot of people look at [Heron of Alexandria's Aeolipile]( URL_0 ) and say \"Oh, if only we could have built on that, we could have had an Industrial Revolution around the birth of Christ!\" Well... no. In order to build steam engines, you would have needed to be able to mine and smelt metal on a scale which would make the materials cheap (which didn't happen), make fuel cheap and abundant (which it wasn't, coal wasn't a thing and deforestation was already becoming a problem in much of the Roman Empire), and make the machines in general so cheap to run there was an economic advantage to using them over slaves or animals (which, because of the above, didn't happen). And that's not even touching on the amount of engineering that would go into turning what was, for practical purposes, a glorified executive's toy into an economically viable source of power. Lack of supporting knowledge: A lot of times, the theories we deride as \"primitive and stoopid\" actually make perfect sense, given the source data. Take the miasma theory of disease, for example. If the observational data you have is \"Touch stuff that smells like shit, get sick, hang around stuff that smells like shit but don't touch it, get sick, stay away from stuff that smells like shit, don't get sick\", the leap to \"smelling things that smell like shit makes people sick\" is a significantly shorter one than \"parasites we can't see are jumping onto us from the things that smell like shit\". It is also way more useful as an explanatory model than \"sometimes gods make us sick\". Scientific arrogance. It's a lot easier to proclaim yourself smarter than dead people than to actually check what they got right and what they didn't. Scientists are also just as status-conscious and prone to insult-trading and slapfighting as anyone else, and a lot of times the proponents of an old theory have to die off before a new one can gain traction. Good ol'-fashioned racism. The British spent a century inventing conspiracy theories involving Atlantis and the Jewish diaspora instead of admitting that it was possible black people built the grand cities of central Africa like Great Zimbabwe. The Chinese insisted that China was the most advanced civilization in the world and had nothing to learn from the outside world until the British Empire showed them the hard way that they did and kicked off what was known as the Century of Dishonor in China. Genuine losses. While the importance of the Library at Alexandria and the Baghdad House of Wisdom are generally overstated, some bits of knowledge were genuinely destroyed and needed to be re-created.",
"All that knowledge was only for the elites. Most people in most cultures would have been completely illiterate. Imagine if all the knowledge of a culture was aggregated into a small college campus. If there was a generation that didn't really care about a certain subject, that subject would stagnate for a hundred years. And how often would you come across someone who actually digs into a subject? Even more rarely would you come across anyone trying to upend conventional wisdom. And worse yet, when there was a serious war, one side of nobles might be completely eliminated along with their knowledge of a subject until someone from the winning side decided to research the old archives. In some cases as with the ancient Mycenaeans losing literacy in a certain language meant that huge amounts of that cultures knowledge would be lost until it was rediscovered by someone new. That was the norm for all of human history until the enlightenment. Advancement was extremely slow.",
"It probably had a lot to do with the fact that the major political authorities would collapse without having tried to share much with neighboring empires - the fragmentation and fall of the Roman empire, for example, left much of europe in near complete disarray, and the resulting groups were probably more concerned about survival than technological advancements. The same likely happened with Egypt and several other of the middle eastern empires. I'm no historian but it seems like the middle east in the ancient days was conquered and reconquered every few decades",
"Many important Greek works were rediscovered during the Italian Renaissance, like [Aristotle]( URL_0 ) and some [Plato]( URL_1 ) and others. This had an influence on humanism and led to a new emphasis on the Greeks. After this, Greek became an acceptable language to study; very few people in Europe knew Greek before the recovery of Aristotle. Egyptian hieroglyphics were never well known in the Western world, not even in the Roman Era, but we started really deciphering them in the 19th century. With that said, everyone knew the Egyptians and the Greeks were lit because the Romans would write (in Latin) where their ideas came from (e.g. this theorem is from Pythagoras, this philosophy originates from Zeno). They got credit in that since, but they weren't as emphasized as the Latin works. Another thing. Before the advent of the printing press, you required a certain amount of political development and social trust for knowledge to really proliferate. No one is going to be putting their head down in books if they're constantly being invaded by neighboring armies. It's not worth the investment. The monastery system and Christianization of Europe helped here *immensely*. Scandinavia only became properly Christian around 1000, and that's a big deal because in 800 you had Vikings raiding and pillaging monasteries, not to mention the Muslim Empire in the South raiding and pillaging monasteries. So with all of Europe Christian, and insulated from outside threats, and with monks being off limits for killing sprees, the monks were able to travel and share ideas with a level of safety and security that is historically unprecedented. Much of the rediscovery of ancient works were the result of monks and priests, almost all of it actually, whose entire existence was putting their head down in books, translating, learning ancient languages, and shooting the shit over brewskies, naturally leading to creative discovery.",
"I think a lot of it has to do with the internet. Now that I can get live info from hundreds of miles away to the point that I can trust buying and selling stocks, any new research is instantly global and available to everyone. Before, if Aristotle, one of the timeless great minds of his time, thought of something, that information was probably only available to the wealthy elite and also likely wouldn’t leave the country for years."
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lztbm4 | How does a cavalary charge work? | I don't understand why Horses wouldn't be afraid to charge into a wall of humans with weapons. And if they would do it, wouldn't the first row tumble and all the other incoming horses would trip over them resulting in a domino effect? | Other | explainlikeimfive | {
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"Training Training Training Also avoiding the pointy end! You can't just take a random horse from a farm and drop it into battle and get good results You have to train the horse to follow commands and to do so during the crazy noise of battle. Horses are skittish creatures, modern ones get terrified by plastic bags so convincing them that you really do want to charge full speed towards all the shouting and clashing metal is difficult, you have to spend many years riding them around those noises and riding in formation with others during those conditions so that when it comes time for the fight its just another training day and nothing bad has happened around those noises before. The most important thing for a cavalry charge to be successful though is to *not go in the front*, don't charge the pointy end! Cavalry gets destroyed by pikes and spears, that's why so many armies used them for so long, but pikes are spears require staying in a tight format and can't turn effectively. If a group of spearmen are fighting another group then you can hit them from the back or sides and at most one rank of guys will be able to turn and stick you with the pointy end, but the rest won't be braced in the right direction and will just get tramped by the horses. Horses are big creatures, generally over 1000 lbs, when people get hit by a horse they go down and the horse tends to remain upright.",
"You're absolutely right. And in cases where a solid formation held their ground, they failed for exactly those reasons. A head-on cavalry charge was a psychological tactic, designed to try and get the enemy to break their formation upon which they would be promptly routed. Alternatively, you could attempt to charge from their flank or rear where they were unprotected.",
"Give horses some credit. It is highly unlikely that horse would just tumble like that. They are freakish big and strong. A 1000+ pound war horse in full gallop will trample any human and barely feel it beneath its hooves.",
"Other answers here cover the mechanics of a cavalry charge pretty well, so I'm going to go somewhere else. What most amateurs underestimate is the importance of the cavalry charge as a psychological weapon. A cavalry charge is essentially the world's largest game of chicken. The cavalry is displaying a threat, consisting of tons of muscle and steel and murderous intent coming at you very fast. They want whatever they're charging to go \"Bugger this for a game of soldiers!\" and try to leg it. This will probably end badly for whoever is running, since they are limited in their means to fight back, disorganized and showing their backs. The chargees, as it were, want to stand still and present a threat of their own, usually in the form of pointy sticks (with or without bang, depending on the time period). However, this only works enough people actually present a threat. If the horses see a hole in the wall of pointy sticks they will head for it, because horses are, as OP rightly observed, much smarter than their riders and not keen on dying. The chargers, can, of course, head back and start again if it looks like the chargees ain't moving, but at the same time, they want to get as close as possible to present the most credible threat. And so, the great game of chicken goes....",
"Correct. Cavalry charges are great for hitting routed armies and finishing them off while they retreat, especially if they retreat in poor order",
"[This post from a military historian]( URL_0 ) should be helpful, especially if you've seen *A Game of Thrones*.",
"Horses don’t run in to dense formations of jeering warriors anymore than they would a wall. This is why the British square worked, cavalry could do no more than circle the formation and take pot shots. Before gun powder the best you could do would be to turn at the last minute and gallop along the length of the enemy line thrusting with spear or slicing with blade. The romantic image of a cavalry charge is not what it is often portrayed to be in art work or film- yes they might be committed into an exposed flank or rear as a desperate attempt to route the enemy but more often they would be use to run down broken forces or as a means of area denial. They could of course be used to attack loose formation were there would be space between the combatants to allow free movement. Other than this it was more common for them to be used in a skirmish role, think mongol horse archers who could stay mobile whilst engage with their bows, whittling the enemy down, or later dragoon’s who were used as a sort of mobile rapid response force-redeploying quickly on horse back before dismount and engaging on foot. There were of course heavy cavalry but they were mostly used as I have described. In the medieval times the ‘knights in shinning armour’ were inevitably noblemen who had every intention of going home after the battle. They would usually let the peasantry do the dangerous bit before swooping in to claim the glory once the worst was over. There are of course always exceptions.",
"You can get a properly trained horse to do all kinds of things, including charging a spear line. Especially if there's other horses close on either side, so they have nowhere else to turn. Elephants, however? They are much harder to train, which has lead to embarassing moments in military history when an elephant charge pulls up short and refuses to go near the pointy sticks."
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lztlau | How do software bugs and glitches develop over time if there is no organic matter? Does digital, intangible software also suffer from "wear and tear"? | Always seemed weird to me that perfectly functioning software can develop a glitch or an error over time, what causes it to degrade? I just don't understand how something intangible can become corrupt or broken over time. | Technology | explainlikeimfive | {
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"Software glitches rarely develop over time. It usually just takes time to discover them because they’re often only replicated in certain circumstances. The problem is that in the process of fixing glitches 1 and 2, you may have created a slight change in the software that leads to a 3rd glitch that doesn’t get discovered for another couple of months",
"Hi, there are a couple of things, that can cause bugs in the late lifecycle of a software: 1. The bug might have been there all along, but didn't impact, because it needed a specific situation to show up. 2. Software is rarely shipped and left alone. Usually there is a process of continous improvement, which means a lot of changes over time. One of these changes might break previously working features. 3. Most software will use external APIs and libraries. Even if the software itself doesn't change, changes in those external dependencies can break features. 4. Something might have accumulated over time until it reached a point, where the software can't cope anymore. Think amount of data, that can be processed or number of daily log-files, that can be written. Hope this helps.",
"Glitches/bugs are either mistakes in the original code or don't account for all possible situations. It doesn't wear out over time- it was always going to happen under the right circumstances. Like, imagine I told you that a number plus another number will always result in a larger number. You would be right until you ran into 0, which would break the original logic, or if you ran into negative numbers.",
"Software doesn't exist alone - it interacts with operating systems, other software, data, and users. All of that can change and thus reveal a weakness that was irrelevant before.",
"There are three main causes 1. Software that is heavily **stateful**, has a lot of internal state changes that can build up over time, can get into configurations that don't run right (this is why, for example, Firefox asks you if you want to \"refresh\" it if you haven't launched it in many months) 2. The ecosystem around it changing, assumptions that were made when the program was written no longer holding (this can be anything from OS-level library support \"evolving\" underneath it, to cryptographic primitives being more breakable than they used to be.) 3. The software _itself_ changing, via updates which cause it to run slower and gain bugs it did not have before",
"Most points were already mentioned. One that I want to add: Humans think linearly. So software is used linearly, and it is programmed with linear thinking. Which means that there is usually a start to the interaction of the software and a process that programmers envision the user going through. Which in turn means there is probably also a very linear process to how the software is tested. There is a constant rate of error even the best programmers have. So as you as a user navigate the process, with every interaction with the software you are rolling the dice anew. It's possible that the first roll already uncovers a bug (which was always there, you just didn't see it). And the more often you role the dice, the more likely it gets that you run into one of the errors.",
"I was only really able to comprehend programming when I started playing lots of factory games. You make 1 section correctly. Cool, you move on, you make a second, a third a fourth. Eventually you're on your 28th section. Wait a second....something doesn't add up. Looks like you missed a small piece on section 15 a while back. That error bled into other sections and now you have to redo section 15 and reset everything after that to get it to work right. I know it's not actually the same, but basically a system starts as really simple like 2+2. But eventually after tons and tons of calculation the reallllly small simple error you had in your programming, or redundancy or whatever, gets noticed because it's amplified by the rest of the program. They are complex natural systems that grow until they are so complicated that rare occurrences happen which don't always yield a good result!",
"It's not degradation or a development. It's more than likely that something in the code, a specific set of conditions or amount of data or whatever, is exposed or found. There is no wear and tear in code but there is data moving to and from. A lot of times, let's say in a game, a bug or glitch is just a specific set of things happening that expose something in the code that is undesirable. Sometimes they go unnoticed bc the quality assurance and testing sizes are almost always smaller than the millions of people using it in the public. So that could be part of the reason it seems like a problem develops, when in reality it gets brought to light either by the user inadvertently painting the software into a sort of corner, or the incoming data causing an issue of some kind. But the data part would still be a fault of the software, as it should have been compensated for during testing for it's specific use",
"Usually it's obscure bugs that only get noticed in extremely specific circumstances that just don't come up in regular use. Then one day you need to use a particular feature in a way you've never used it before, and bam. Example: I had a client years ago who had done all their accounting on an Apple IIe for like 20 years with a piece of software that had never been updated. They ran into a bug they'd never seen before in all their years of using it, because they were doing something different than they normally did. It was a fairly simple piece of software, written in BASIC, and the code was visible/editable so I went hunting. I managed to find a simple math error in a piece of rarely-used code and fixed it, and they never had another issue. Hardware breaks down over time (entropy), but software stays the same. I'm sure over very long periods of time the magnetic media degrades, but it's almost always the case that the electronics will fail first."
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lzuq4i | when surgeons remove an organ or amputate a limb, what do they do with the major arteries and veins that were feeding it? | *In the following text I'm gonna try to explain the subject a bit to make the question accessible to those who don't have any kind of knowledge about this, and to clarify my points to those who do know what im talking about (I apologize, it's long, but this is not an easy problem lol):* So every single organ and body part is fed with a constant stream of blood by at least one major artery and one major vein. What leaves me confused is, they obviously cannot just sew the vessels closed because arteries are like insanely pressurized and the venous system relies on that small bit of pressure that is left from the arteries to help push the blood back up towards the heart. If they just took away the organ/limb and cut the artery and the vein and sewed them shut the pressure in the artery would cause it to burst and the closed vein would have no new imputs of blood to push the rest up, resulting in stagnant blood from the vein and a massive internal bleeding from the artery and the patient is dead. Also they can't even remove the whole artery and vein cause: a) every major artery comes from a huge artery that runs through the center of your body called the Aorta, which is like an inch thick and carries *insanely* pressurized blood. You would therefore have to go up to the Aorta to eventually be able to cut off the artery from its beginning to avoid pressurized blood going into it in the first place, but any rupture or cut of that proportions in the Aorta would definitely cause a massive bleeding. Same thing with veins, every major vein ends up in two *gigantic* veins called the Caval Vein and the Portal Vein, that would most likely have the same catastrophic and very deadly outcome. and b) each of those arteries and veins feeds a ton of other stuff and organs and tissues along its way to its primary organ, which would all go necrotic and cause the patient's death. After considering all this I thought the only logical solution would have to be to take the cut end of the artery and the cut end of the vein and sew them together, so that the blood from the artery just bypasses the missing organ and goes directly into the vein, but this carries a major problem: pressure. Arteries are literally made to withstand the pressure the blood has after being forcefully squished out of the heart, but veins are not, as when blood gets into them it's not pressurized anymore. This happens thanks to the capillaries: to go from an artery to a vein blood has to run through a huge net of tiny little vases that actually feed the tissues and that slow down the blood, being so narrow that blood cells can barely squeeze into them and when blood comes out of them it's not pressurized anymore. Veins are actually really elastic cause they have to constantly adjust to the volume of blood that is moving in your body: the most bloode you use, the more the venous pressure goes up, the more the venous system gets bigger in volume. Therefore, attaching the pressurized artery to the very elastic vein would be like filling a big ass elastic balloon with blood from a fire hose, again eventually causing rupture and internal bleeding and killing the patient. So people who do know the answer, please, I beg you, enlighten me cause I can't live without knowing this anymore lmao | Biology | explainlikeimfive | {
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"They sew them shut and it's fine. The blood just stops flowing and the vessel doesn't explode or anything. Surgeons don't usually connect an artery to a vein, unless they are trying to create a fistula for hemodialysis access, usually in the arm. The vein does enlarge quite a bit to create an easy place to place the catheter to the dialysis machine. If it gets too big sometimes it's a problem then they do another operation to decrease the blood flow. Source: I watched a lot of vascular surgeries and amputations.",
"It really is a matter of just cutting the arteries and veins at the point they are entering the organ and sewing them shut (called \"ligating\"). You've got a few things right, but a few other misconceptions that I think are causing you to overthink this. Arteries are not \"insanely pressurized\", but even if they were, closing one off is not going to have much effect. If you think of it as plumbing, the blood will just flow through all of the other arteries instead of through the now dead end one. Veins are also not pressurized by the heart. Capillaries are so small, that the veins don't ever \"feel\" the pressure of the heart pumping. You mention that veins are elastic, and arteries are too to some degree. This allows them to respond to any (small) increase in pressure by suddenly having roughly the same amount of blood circulating through a slightly smaller plumbing system when you tie off an artery. source: am surgeon",
"Tying off an artery is not like trying to plug a garden hose with your finger. It's more like turning off the tap on your kitchen sink. The water supply to your house is connected to the municipal water system, which brings pressurized water into everyone's homes and businesses. When you turn off the tap that pressure doesn't go away, but it redistributes to every open tap in the network. There are so many of these that the change is negligible. When you tie off an artery I suppose you cause a slight pressure increased elsewhere in the vascular system, but this is well within the body's ability to compensate for. Isolating and ligating the blood supply is usually one of the first steps in removing an organ.",
"Your entire concept of the circulatory system is wrong. You are thinking of it like a highway system where there is some central path and all the other organs just have off ramps to siphon off some blood. Blocking the main path would seem to cause the huge problems you mentioned. Except it isn’t like that at all. Instead think of the main output from the heart being split, and then split again, and split again, etc. until all you have is blood oozing through tiny capillaries and the tissue itself. If you block off one of those paths then obviously anything fed from that path will have trouble, but pressure isn’t really going to “back up” behind it because there are plenty of other routes to follow. Another point is that the aorta and arteries really aren’t *that* pressurized. The “insane pressure” is actually only 2-3 psi. That is well within the range of sewing it shut and letting it heal."
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lzuth2 | Why do so many medications have hydrochloride as part of their chemical formulae? | I swear every prescription medication I've seen has hydrochloride in it. What is the purpose of this hydrochloride as it relates to medicine? | Chemistry | explainlikeimfive | {
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"A lot of medications aren't very soluble in water by themselves. This is by design allowing them to dissolve in the fatty lipid layer of the cell membranes and the internal lipid layers of the Golgi Apparatus inside cells. It turns out that many of the targets of given medications are proteins that are normally embedded in cell membranes. Thus, for medications, being oil soluble is important for functionality. Crucially, It allows the medication to cross through the layer of cells that forms the Intestinal-Blood Barrier. Typically, water soluble compounds have a hard time crossing this cellular barrier. In general a certain amount of fats is necessary in the diet for the intestines to absorb nutrients. This is a problem though when it comes to dissolving the pill in the stomach. So they react the medication with hydrochloric acid, producing the hydrochloride salt. This makes it more water soluble allowing the pill to disintegrate and dissolve well. As stomach contents exit through the duodenum, they're mixed with bile from the gallbladder and pancreas. Bile contains a high concentration of bicarbonate ions and is moderately basic which neutralizes stomach acid. This converts the medication into a *Free Base* form that is less water soluble but much more soluble in fats and oils in food, helping it to be absorbed. This kind of chemistry forms the basis of *Acid-Base Extraction* processes. This process is used to seperate certain compounds from a solution, based on them becoming more or less soluble in nonpolar substances when the pH is changed. This is a technique widely used in chemistry.",
"Hydrochloride, when not attached to anything else, is hydrochloric acid. If you remember your fourth grade vinager+baking soda volcano chemistry, acids and bases react with each other to neutralize each other, becoming a salt. A lot of medicines are bases - which means that they're pretty reactive. They'll grab anything they can react with and try to burn/dissolve it. (So will acids). Hydrochloric acid is one of the strongest acids we know, and it's not fundamentally toxic other than being a horrifically strong acid. (Hydrofluoric acid, on the other hand, would probably disagree with your body pretty badly.) So reacting it with a basic medicine neutralizes that medicine's alkalinity, without making it less effective."
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lzv5ti | What is the purpose of "buying" tweets ? Purpose of "owninig" NFTs? | You are still using it "digitally" (i.e seeing it digitally after buying) so why to spend money on it rather than just save those as images if you want on your computer ? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"There’s no purpose except enjoyment. The point is to make a digital version of baseball cards. Because there’s no scarcity in the digital realm, these companies hope that by releasing a limited number of tokens, the tokens will be seen as collectibles. So, for instance, with NBA Top Shot, you buy packs and get several highlight plays. Sometimes, you get a rare one. There’s a market place where people can trade them and buy/sell them like any collectible. I don’t really personally get why anyone would participate. But it’s apparently fun for some people who are really into collecting things."
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lzvavh | How the hell do trick candles work??? | HOW?????? | Other | explainlikeimfive | {
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"gq45dxx"
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"text": [
"Magnesium dust inside the wick. It ignites relatively easily from the small ember, and burns hotter than the ember, reigniting the paraffin vapor and the candle is burning again"
],
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9
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lzvham | Why can't we control how long our epiglottis stays back and swallow stuff continuously? | Biology | explainlikeimfive | {
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"text": [
"Some people can, look up videos of drinking water bottles fast. It is probably a good thing most people can’t because they could try to eat some dumb things without letting their tongue check if it’s bad for them. This would be especially bad for children.",
"If you train, you can learn how to do that. I worked as a driver and such skill was useful to learn. Now I can just pour water and drink as much water as I want in one gulp. You really can learn that and it isn't that hard to do eith practice."
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lzw6l6 | How does polarisation work? | When I was younger we used to go fishing and we used to wear polarised glasses to help prevent with glare from the sun on the sea, but what exactly is happening? | Physics | explainlikeimfive | {
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"text": [
"Polarized lenses have lines placed so close together that the light can only come into the lens if it is traveling exactly perpendicular to the lenses. This reduces glare by greatly reducing the amount of light striking your eyes at other angles. Polarized lenses are great for any condition is where the is light being reflected from multiple directions or light from multiple sources."
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lzwrt3 | How can we taste things on our lips like chapstick or other people's lips? | Biology | explainlikeimfive | {
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"text": [
"The olfactory system also includes your nose, and not just your tastebuds. You get all of it."
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lzxcie | Where does a bird's blood come from? | We get our red blood cells from the marrow in our bones, but we're constantly told that a bird's bones are hollow, so where does it come from? | Biology | explainlikeimfive | {
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"text": [
"Not all of their bones are hollow. Some of them do contain marrow like ours do, and it functions like ours does.",
"Hollow doesn't mean empty. If you compare the cross section of similarly sized animal femurs (turkey vulture vs cat), the turkey vulture bone has thin walls and minimal lattice of bone, and the rest of the space is filled with marrow. Comparatively, the cat femur has much thicker walls, which protect the bone more from the impacts of jumping and running. In both cases, the middle cavity within the bone is filled with marrow [turkey vulture femur]( URL_0 ) [cat femur]( URL_1 )"
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"https://www.researchgate.net/profile/Ekaterina-Novitskaya/publication/318444188/figure/fig3/AS:545550853513220@1507080867743/Microscopic-analysis-of-the-turkey-vulture-humerus-Photograph-showing-cross-sections-at.png",
"https://c8.alamy.com/comp/EY9JF8/cross-section-through-an-model-of-an-normal-upper-right-femur-or-leg-EY9JF8.jpg"
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lzxt9y | I get why we sweat when it’s hot but why do we sweat when we walk fast in cold? | Biology | explainlikeimfive | {
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"text": [
"We sweat when we are hot, not when it's hot outside. So if the exercise warms you up, you'll sweat.",
"Thermodynamic man. You exercise, thus creating energy which is released as heat, warming your body temperature. Body needs to sweat to cool itself down again."
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lzxye1 | When we are about to cry or holding back from crying, why does it make your throat hurt? | Biology | explainlikeimfive | {
"a_id": [
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"text": [
"When you cry, you produce a great deal of saliva. During this, your throat's attempt to swallow that saliva presses on your glottis, which expands when you're trying to stop yourself from crying or making otherwise involuntary sounds. The glottis is the opening between your vocal folds. This act of pressing by your throat compacts your food pipe, which makes it feel \"stuck\"."
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lzyrg8 | Why can't we fly at speeds close to light in space, if we can just keep accelerating? | There is no opposing force too acceleration in the void of space, so if a spaceship kept burning fuel it would continue to accelerate, eventually approaching light speed (we I understand that other laws of physics take over, but I don't know what they are). Why can't we travel at near light speeds in space? | Physics | explainlikeimfive | {
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"As you approach the speed of light you start to need double the amount of force just to accelerate a little bit more, that doubling effect means the extra force required reaches infinity before you reach the speed of light.",
"The biggest problem is HOW do you accelerate constantly? The only way to accelerate is to use the law \"for every action, there is an equal and opposite reaction.\" So, on order to accelerate your space craft in the desired direction, your spacecraft has to accelerate something else in the opposite direction. Your spacecraft has to throw something to accelerate. What is it going to throw? Gases that it's carrying? There's a limit to how much you can carry initially. Electrons or mass turned into plasma? It takes mass to do that. You can try to gather and accelerate the tiny amounts of mass that are sitting there in space. You can also create photons of light and accelerate those. The mass * acceleration of the stuff you accelerate will match the mass * acceleration imparted to the your craft. So, theoretically, you could, but only as long as you have a mass to accelerate. Finally, as you approach the speed of light, the mass of your craft will increase but your reaction mass will become less effective because it's velocity will be somewhat less than it was when it was on your craft.",
"There is a proposed mission to the Alpha Centauri system, our nearest stars (well, our nearest stars *after the Sun*), called [Breakthrough Starshot]( URL_0 ). Basically, they want to build a thousand mini-spacecrafts, each one with a solar sail (a sail powered by light), and propel them using lasers so they reach a speed of 15 or 20% the speed of light. One of the main problems is the propulsion itself, that's why they propose those mini-spacecrafts so they minimize the mass needed to be propelled, and compensate any problem or defects with having a big fleet.",
"To accelerate, you need to burn fuel. And that fuel had to be accelerated as well before. Which needs more fuel. Which also had to be accelerated before. And so on. The amount of fuel you need increases exponentially with your target speed. At the efficiency of current engines (taking the Space Shuttle main engine as an example), even 7 km/s (=min. orbital velocity) requires 8x as much fuel as you have payload. And that's only 0.002% of the speed of light. To get 1 kg to move at 1/3 the speed of light, you'd need e^(1E8 / (9.81*452)) kg of fuel...a larger number than Google Calculator can handle."
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lzyscy | what is Axis of Evil in astronomy and why is it troubling astronomers? | Other | explainlikeimfive | {
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"text": [
"The name's a little melodramatic; there's nothing \"evil\" about it. Current models of the early stages of the universe (colloquially the big bang theory) suggest that the universe should be roughly the same no matter where you look. A single massive explosion should throw off matter in all directions. There's something called the *cosmic microwave background*, sort of the afterglow of the Big Bang, and it's what we look at to judge this uniformity. Certain observations back in the early 2000s, however, suggested a special significance to the plane of our solar system; oddities and patterns unlikely to have arisen by chance. These observations were confirmed twice over in mid-2020. This is troubling, because it raises questions about the nature of the big bang and the early universe.",
"Basically in looking at the cosmic background radiation astronomers expected it to be virtually smooth, but instead it appears to have patterns of lumps and bumps in it which have yet to be explained fully."
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lzz2e1 | Why can't water get hotter than 100 degrees Celsius? | It only evaporates faster, but the temperature is max 100 degrees. | Chemistry | explainlikeimfive | {
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"You *can* get water hotter than 100. The key thing is that when water turns into water vapour, it cools down. So when you boil water, it heats up until the rate of heat loss from boiling equals the rate of heat gain from the heat source. Then it's being heated and cooled at the same rate, so it doesn't change temperature. 100 degrees is the point where this happens at sea level standard pressure. To get it hotter than 100 you need to stop it boiling, so you can either increase the pressure, or you can have the water in a perfectly smooth vessel with no nuceleation sites. You can then heat water hotter than 100. It's quite easy to microwave water hotter than 100 in a glass, but that's really dangerous. As soon as the water is picked up, the vibrations will often cause it to suddenly boil. See URL_0",
"It can. You need to increase the pressure of the surrounding environment. That is why pressure cookers ate a thing.",
"That is not evaporation. At about 100°C it actually changes its state from liquid to gasous. This change needs extra energy, that's why water appears to not get hotter. But that is only at atmospheric pressure. If you increase pressure water gets hotter than 100°C before it boils off.",
"Evaporation has a cooling effect. The more heat you add, the more evaporation and the faster it cools. The only way to get the water hotter than 100 degrees Celsius is to stop the evaporation and that means you need to add pressure."
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lzzre1 | How is hydrogen (fuel cell?) used as a fuel source and why isn’t it more widespread? | I’ve been looking into renewable energy and other options relative to nuclear (not a big fan because of the waste), solar, wind, and thermal. Hydrogen fuel cell technology has popped up a bit and I’m wondering how this works. With my basic understanding, hydrogen is used as input and water (two hydrogens and an oxygen) are the output. How does this reaction happen? Is it not widespread because it’s energy intensive? If not, why haven’t more industries adopted this technology? If so, why is so energy intensive and how much energy does it produce? What’s holding us back from going balls deep into hydrogen fuel cell technology when the by products are clean (even usable) and the input is so abundant in the universe and on earth? With the abundance of input material, It seems like this technology could be useful once we get to Mars as well. Disclaimer: This isn’t for a class or anything. I’m a 31 year old bioinformatician just looking into a new interesting topic and wanted some context from someone with more knowledge. | Technology | explainlikeimfive | {
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"Because it's not really a fuel source as much of an energy storage system. The hydrogen needs to be created from water using electrolysis, and it will use as much electricity to do that as it would take to make an electric car go the same distance, if not less because of inherent inefficiencies any time one form of power is converted to another and then back to another one again. So on top of that, it's dangerous to have a big tank of highly compressed gas in a car. It's simpler to just store the electricity directly with batteries.",
"TLDR: We can't yet produce Hydrogen quickly or efficiently enough to use Hydrogen as a fuel source for cars. > I’ve been looking into renewable energy and other options relative to nuclear (not a big fan because of the waste), solar, wind, and thermal. Hydrogen fuel cell technology has popped up a bit and I’m wondering how this works. With my basic understanding, hydrogen is used as input and water (two hydrogens and an oxygen) are the output. Hydrogen fuel cells have existed for decades and were in fact used as power generators on the Apollo missions. Hydrogen and Oxygen are pass through the fuel cell where the combine to form water. This process releases an electron which creates an electrical current. > Is it not widespread because it’s energy intensive? If not, why haven’t more industries adopted this technology? It's not widespread because free Hydrogen is difficult to manufacture. Current processes either decompose fossil fuels (which doesn't eliminate our dependence on them) or use electrolysis to break apart water molecules. We don't have the infrastructure or technology yet to make hydrogen on any kind of practical scale. > What’s holding us back from going balls deep into hydrogen fuel cell technology when the by products are clean (even usable) and the input is so abundant in the universe and on earth? We need to find an environmentally friendly and efficient means of produce vast quantities of Hydrogen. Other problems like safe storage and transport are fairly straight forward to resolve by comparison. > With the abundance of input material, It seems like this technology could be useful once we get to Mars as well. Yes, fuel cell technology is very relevant in terms of space travel. Hydrogen is the most common element in the universe and Oxygen is also abundant. It just happens that we don't have access to large quantities of raw Hydrogen on Earth, almost all of it exists as water.",
"I'm not an expert on fuel cells, and the physics is out of my area, but I do know about the limitations. 1. Where do we get the hydrogen? We end up getting it from water, but electrolysis is energy intensive, so no matter how efficient your fuel cell is, it is always hampered by the fact that water is hard to break apart. 2. Where do we fill our fuel cell cars? We just don't have infrastructure yet. It's the same issue with electric cars, but to an even greater degree. 3. Storage Hydrogen is a flammable gas, and the only way to store it efficiently is to pressurize it. That's a bomb. It's not impossible to overcome any or all of these issues, but they are the reasons why we haven't dove headfirst into hydrogen as an energy source.",
"Additionally, hydrogen production is an inherent process of nuclear reactors. Radiolysis reactions of ionizing radiation and water results in H2 production. Should we implement a mechanism to harness that hydrogen, it would be yet another reason to rely upon nuclear power. The “nuclear waste” isn’t a scientific issue as much as a political one. The “Waste” generated from nuclear reactors is actually composed of approximately 95% reusable fuel. Other countries, such as France and Japan, already reprocess the “spent” fuel to make it reusable. A long time ago in a galaxy far far away, Congress arbitrarily decided that the fuel from reactors would be discarded instead of reprocessed (due to “proliferation concerns”). This was an extremely short sighted decision that did not consider the possibility of a federal repository failing to be built. Yucca mountain was the US governments Plan A, B, C, and D. Since it is unlikely to ever receive nuclear waste, we should instead begin developing means to reduce the current inventory of waste. If your primary concern against nuclear energy is the waste issue, you would agree that reducing the waste by ~95% is a goal worth implementing. I will note, I am assuming you are US based (as I am), but the logic behind my response holds universally. Especially since the vast majority of the Nuclear World implemented US strategies on waste handling. My kudo’s go out to those who went against the mold (France, Japan, Finland by my last count. Hopefully More exist)."
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lzzwxm | Why do streaming services care about the number of episodes viewed in a sitting. | I like to have background noise throughout the day which results in Netflix and Hulu continuously asking for me to “make sure I’m still here”. My question is why does it matter to them? | Technology | explainlikeimfive | {
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"text": [
"Using their service costs them money for bandwidth or whatever. Streaming to an empty room or to a sleeping person costs them more.",
"You have to remember, they have millions of customers. Bandwidth (used to deliver the stream to you on demand,) isn't free. They're trying to make a profit. If every account played forever when someone pressed play, there would be so many zombie streaming devices playing for eternity eating bandwidth with no viewers. It's basically a way to ensure that, for the most part, viewing is done by actual people wanting to view the service - it saves on bandwidth a ton."
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m00ljk | Why do some medications and vitamins say that you have to take them with a meal? | Biology | explainlikeimfive | {
"a_id": [
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"text": [
"A lot of medication is particularly hard on the stomach. NSAIDs (Non-Steroidal Anti Inflammatory Drugs) like Advil for example temporarily disable your stomachs ability to produce mucus that protects the stomach lining. So extended use of Advil for some people can cause ulcers as the stomach acid burns away at the stomach lining. Eating with food reduces this effect.",
"Some vitamins are fat soluble which means they dissolve in fat. In order to digest the vitamin your body has to break it down and fat soluble vitamins break down much better in fat, so if you eat some food along with the vitamin it will absorb better",
"Some vitamins are better absorbed when the digestive track is prepared to absorb food. Also, some substances can be corrosive to the gastrointestinal tract. Food acts like a buffer in this case. More detailed information can be given by someone who isn't a lazy sack of crap like myself."
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m013rj | Why are guitar strings so long? | I just changed the strings on my Yamaha acoustic after about eight months, and it was a hassle. I repeatedly had to go back and adjust the amounts of slack given to each string because I didn't leave good amounts the first time (I was smart enough not to trim the ends until I was satisfied with the windings). Why add so much slack if it won't all be used? it's wasted material, and it makes a guessing game out of something that shouldn't be very difficult. When I played violin, it wasn't a problem --- the entire length of the strings was used. | Other | explainlikeimfive | {
"a_id": [
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"text": [
"Guitars are all different sizes, 100's. 1000's of different guitars made around the world, an extra 5 or six inches of metal wire, makes guitar strings pretty much a one size fits all product.",
"Different scale lengths, different headstock designs (double sided vs single sided), and differing tailpiece positions behind the bridge, I would suggest are the main factors."
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m01arr | how do astronomers know the size of objects in space? | For example, if something would be a few light years wide, would that not mean we would have to use a thing to map it out for that amount of light years in years to get the actual map? Or do they use different methods, like scaling things close to it? | Other | explainlikeimfive | {
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"text": [
"They are very educated guesses. The mass can be well calculated for anything with a moon or planet orbiting it thanks to Kepler’s equations. The size and density are estimated based on mass and luminosity (how bright it is). For some things like stars that resemble our sun, this is a good guess. For other things, it is an educated guess."
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m02gr9 | Do non-sentient creatures have the ability to experience fun? | Other | explainlikeimfive | {
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"text": [
"I mean I guess that would depend on what definition of “sentient” you use. We’ve all seen our pets have fun, and I know I’m not the only one who has seen farm animals and “game” animals playing. Dolphins have been known to surf and get high (using pufferfish) which IMO makes them typical surfer dudes. I guess this question applies better to “lesser” animals like insects, crustaceans, corals, etc.",
"The definition of sentient is the ability to perceive or feel things. So a non-sentient animal, by definition, cannot experience the feeling of fun, or any other feeling for that matter."
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m03gn0 | What's the consequences of Godel incompleteness theorem? | Mathematics | explainlikeimfive | {
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"The primary and immediate consequence of the theorem is that you will never be able to root all of mathematics into some finite axiomatic system. Prior to his theory, the goal was to reduce math to a as few unproven axioms as possible, then derive all of mathematics from them. Godel showed that this is in vain. You will either have a system that has contradictions (is inconsistent) or will be unable to prove some things that are actually true (is incomplete).",
"The other explanation here is pretty good, although I would nitpick a little: the Incompleteness theorems do **not** say that we will be unable to prove some things that \"are true,\" since a statement by definition cannot be true in an axiomatic system if it cannot be proven from that axiomatic system. A better way of phrasing this is to say that the Incompleteness theorems imply that, in any consistent and sufficiently rich axiomatic system (i.e. any set of axioms that do not allow you to prove contradictory statements and that are complex enough to model arithmetic), there are some statements that are undecidable, meaning that, while we can state the statement in the language of the axiomatic system, we can prove neither the statement nor its negation from the axioms. An example in the axiomatic system ZFC (which is the standard axiomatic system for set theory and lies at the foundation of most modern mathematics) is the Continuum Hypothesis, which is the statement that there exists some set whose cardinality is strictly between the cardinality of the integers and the cardinality of the reals. We cannot prove CH to be true or false from ZFC (and we can prove that this is the case!). Furthermore, if we were to add on to our current set of axioms (ZFC) either the assumption that the CH is true or the assumption that CH is false, we would still get a consistent system; that is, our axiomatic system \"doesn't say anything\" about CH and doesn't care whether or not it's true. For a list of some other statements that are provably undecidable in ZFC, see URL_1 . One statement that might catch your eye on that list is the consistency of ZFC—indeed, we can prove that we cannot prove, in ZFC, whether ZFC is consistent or not! (This is the second Incompleteness theorem of Gödel, where he showed that if ZFC can prove that ZFC is consistent, then that implies that ZFC is not consistent.) But this is actually not a huge deal. For more on this, see the answers on this page: URL_0 . In short, there is a real difference between truly formal proofs (which use rules of inference and a set of axioms to prove statements in a formal system) and the sort of proofs that most mathematicians actually do on a daily basis, which are far more high-level than truly formal proofs. So the fact that no formal proof exists of certain statements really doesn't end up being a huge deal. Unfortunately, at this point things become very, very technical very fast, and it's basically impossible to ELI5. (Just look up \"cumulative hierarchy\" or \"reflection principle\" to see how complex things get.) There are also some possibly very simple examples. Suppose I define an axiomatic system that defines the notion of a car and the notion of color, and the notion that a car may be a certain color. Then let X be a car and consider the statement \"X is red.\" This statement is undecidable from my axiomatic system, since X could be red or could be not red, and either way no contradiction emerges. That is, I could create an axiomatic system where X is red, or one where X is not red, and both would be consistent. Note that the Incompleteness theorems apply not just to ZFC, but to any axiomatic system meeting certain requirements, which are too technical to ELI5 without oversimplifying. And one last note: The Incompleteness theorems absolutely do not mean that \"math is beyond human comprehension\" or that there are \"some mysteries in math that we will never find out\" or any such thing. They have very precise implications in terms of the properties of axiomatic systems, and any grandiose statements like the above are just gross misinterpretations of the precise results. Unfortunately, the theorems are too technical to state with complete precision to a non-expert, so they are frequently misinterpreted. This is also the reason it's basically impossible to give an accurate ELI5 about these theorems, since they deal with concepts like \"truth\" and \"provability\" that have precise mathematical meanings that don't necessarily align with popular use of the terms; hence, any truly simple description of the theorems will almost certainly gloss over crucial details and promote a misinterpretation of the theorems.",
"Every math has rules that are “just because”, called axioms. In the past, people tried really really hard to find a small number of “just because” rules to be the base of all math. Godel proved that this was impossible, so people stopped wasting their time trying."
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m03keq | Why is unemployment so high but every job I have had the company is crazy understaffed? | Economics | explainlikeimfive | {
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"If feel like the job I work for stays understaffed so that they can capitalize even further on the record profits they are getting due to the pandemic. Or there is still a portion of the population that still doesn't trust that employers will protect their health during this crazy time. There's probably a ton of other reasons my small brain can't come up with as well.",
"There are a couple of thoughts... There are many service industry workers who are unemployed. The jobs you are talking about are probably not the same jobs that would find service industry workers as suitable candidates for the position. Unemployment is not uniformly distributed across the place. You may live in a place with less unemployment than other places. So your personal observation is not a good measurement for the general trend. FYI that applies to most topics. Some industries are not willing to pay wages that would allow a person to live where they work. Using a personal observation is probably not going to explain most general phenomenon. Or as my father the 100 year old college professor has said, \"all Indians walk single file, at least the one I saw did.\""
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m046x2 | The difference between 4WD and AWD. | Other | explainlikeimfive | {
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"AWD is all the time, 4WD is selective, but there’s usually two options. You’ve got 4WD high, and 4WD Low. You can use the high gear version for snow and stuff like that at regular speeds but 4WD low is for getting out of super muddy places and/or pulling things. 4WD low is what I would use to pull a stump cuz it’s got a lower gear, better for pulling"
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m04nln | If a company or website gets hacked, why does it matter how strong my password is? Isn’t it more important that I don’t re-use a password? | If a site gets hacked, am I at any sort of advantage by having a complicated password, or does it not really matter at that point? | Technology | explainlikeimfive | {
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"Any company worth its salt will store your password in a form called a hash. This is you password scrambled up and reduced in size with math, so it’s near impossible to get your original password back. The standard practice for hackers once they get the hash is to do the same math at all sorts of different passwords to see if your hash comes out. This is the reason you have complicated passwords. More possible different passwords make this so much more difficult. So once they plug the hole in their security, the hackers won’t be able to just log in using your password. They wouldn’t have figured it out.",
"Companies don't store your password. They store a hash of it which is a type of encription(over simplifying I know). Hackers still don't know your password, but they can guess passwords until they get the same hash to find it. If you use a really strong password they will probably never figure it out so you will be OK. But if it a weak password they will figure it our pretty fast. If you never reuse passwords tho, it won't affect you very much.",
"TIL that hash is much more than a delicious breakfast food. Thanks for the great responses everyone!",
"some shitty websites will store your password in plain text. but any good/legit website won't. so if you use the same password in all websites, then yes it doesn't matter how good your password is if the plain text website gets hacked. good/legit websites store the password's hash, which is your password after running it through a bunch of math (ie encryption). since most websites use common encryption methods, then the hackers can reverse engineer what your password is by guessing the encryption method and seeing if they can match the hash. the more common a password is, the more likely they are able to match the hash. so yes, it's best to use a combination of a strong password and also not reusing your passwords.",
"It very rare for hackers to directly get your password. Any decent website doesn't actually store your password; they store a \"hashed\" version of it. This is why when you hit \"forgot my password\", the website has you reset your password instead of just sending you your password: the website doesn't actually know your password. So, if a site gets hacked, and the hackers get the hashed version of your password, they can't actually use it to log in. However, they can try to guess your password, and they'll know they guessed correctly if their guess has the same hash as the hashed version they got from hacking. This lets them try millions of guesses per second, so they'll start by guessing millions of simple passwords. But if your password is complicated, they probably will never guess correctly, because there are trillions of trillions of possible complex passwords."
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m04s2s | What causes a scab to be itchy? | Biology | explainlikeimfive | {
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"Your skin evolved to be very sensitive to tiny movements on your skin (bugs crawling) and causes you to feel itchy. There's a fiber scaffold under your scab that helps close the wound and allow cells move in to rebuild. As the wound heals this scaffold is pulled together to help close the wound. However, this pulling triggers the nerves sensitive to light touch, and causes your skin to think there's something crawling on it making you feel itchy. It's bad to scratch off your scab since it may reopen the wound, increasing the chance of scarring. You can scratch around the scab to help relieve the itchy feeling without disrupting the wound healing."
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m04xll | Infinite in Physics | I've heard many times how there are issues with certain theories when they end up with infinite results. Is the idea that "infinite" can be the truth ever explored? I feel as parts of the system we can't see the whole system at work, so why can't there be endless results? Is it just we don't think it can exist so it must be wrong or..? | Physics | explainlikeimfive | {
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"Let's try to imagine some infinite quantities * Infinite energy- immediately, everything in the universe decomposes into it's constituent parts, and/or a black hole the size of the entire universe is formed * infinite mass- similar to infinite energy, a black hole the size of the universe is formed * infinite electric charge- immediately rips all electrons from their protons, flinging all protons away from it as fast as possible. The only one that is even considerable is \"infinite spacetime\" because we do not see any end to it, and nothing about it breaks physics in the ways I showed. You can sometimes approximate large values as infinite, but actually getting to infinity just doesn't work, it implies things that we just don't observe.",
"The problem is that infinity isn't really a number, not in the same way that 5 or 67 or 1.73x10\\^20 are. You can't reach infinity just by going up the number scale: think of the largest number imaginable and then add one to it, and the result is still a finite number. Infinity is a concept for when something is unbounded or unquantifiable (cannot be expressed as a number). So it's intrinsically incapable of describing something that we know can be described by finite numbers. Just as you can't have aardvark units of mass, you can't have infinity units of mass either. It's a nonsensical result. (Before the math nerds get here: Yes, infinity *is* a number but \"number\" doesn't actually mean what the average person thinks it means. That... is a much more complicated topic however, and one I understand very little.)",
"Math is a tool for describing physics. There are things that you can write in math that don't correspond to reality. The density of matter in some volume of space can be any value, including infinite values, in math, but not in reality. When the density gets too high, a black hole is formed and the normal rules of physics stop working. So, our math is close to reality, but not quite right. This is clearly a problem with our choices for math formulas, and we need to find some new math formulas to fix the situation and bring our math closer to reality. Just because math allows something doesn't mean reality allows it. Our math isn't reality, xt's just our model. Our math could be wrong, we've found many flaws in the past and nobody thinks physics is \"done\"."
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m06wbq | What are NFTs, NFT art and how is it possible that someone can make money selling a JPEG or gif that is already viewable/downloadable by almost anyone? | Technology | explainlikeimfive | {
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"An NFT is pretty much a certificate of authenticity for digital items. Let's say an artist paints a painting, and then also sends it to print (meaning you can have hundreds or even millions of copies). But there is only one original, that the artist herself painted with her own brush, even though there are many copies. So why would I want the actual original Mona Lisa when I could just get Mona Lisa printed on canvas and it looks good enough? Sure it's a Mona Lisa, but it's not *the* Mona Lisa that Da Vinci himself did and which is considered priceless. NFT pushes that concept to the digital realm as it becomes more and more common for an artist to use a digital medium, using paint programs to create drawings and paintings. So while there may be many copies floating around out there, there is only one true \"official\" original, and the NFT provides a chain of custody to verify it, since digital copies are perfect replicas of the original data, unlike a canvas print versus actual paint and brush on canvas. This opens avenues for digital art to be treated more like traditional art, for the sake of preserving its value or even just as a proof that it is the 100% unadultered original creation of the artist, not shrunk now and again to conserve bandwidth or run through effects on editing programs to alter details; it is exactly what the artist intended.",
"I only heard about them recently on NPR. Its apparently the digital rights to a digital object. I can't fathom why someone would want to buy an NFT, but some people have enough money to buy stupid shit."
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m085ld | Why is a crowd cheering any louder than one individual shouting, if everyone is shouting at the same volume? | Other | explainlikeimfive | {
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"You know how when you're in the bathtub and you're splashing and it makes a wave in the water and then when it ripples back to you, you're still splashing around and the wave gets bigger? Sound travels in waves, and when those waves are stacked on top of each other, like in a crowd, the size of the waves get bigger and is therefore louder.",
"Think of it a bit like light from a candle. Each candle is putting out the same amount of light, but if you put 100 of them in a room, it will be bright. The light, like the sound from the voices, gets added together.",
"Just to add on a weird but cool fact... doubling the amount of people doesn’t double the sound, it only increases it by 3 db. So the sound of 20,000 fans cheering is only 3 db louder than 10,000. Most people perceive 10 db as a doubling of the sound, so 20,000 fans is only twice as loud as 2,000.",
"Ooh, I learned this a long time ago. When you're adding two sound sources together to find out how loud the total is, you use this thing called power summation. Without getting too deep in the specifics, think of an example of two guitars next to each other both perfectly in tune. The same string is plucked on each one. If they are within 10 decibels of one another, the resulting total sound will be louder than either one individually. If they are more than 10dB apart in intensity, the total volume will only be that of the louder one. If they're equal in intensity, the resulting sound will increase by 3dB, which is a doubling of intensity. When you have a bunch of sources of sound, it gets really complicated to add everything together, but the math doesn't really change. You're still going to get a much louder sound than any individual . Note: this ignores things like destructive interference, which is how things like noise-cancelling headphones work. It's a very simplified explanation of how the energy is summed up from multiple sources, but it should give anyone a rough idea of how it works."
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m08wh1 | Why does Niagara falls not run out of water? | It goes down no? | Earth Science | explainlikeimfive | {
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"Simply put, the water cycle. Water evaporates, is condensed into clouds and falls as rain. Fortunately for the falls the jetstream air current flows over the Great Lakes picking up all that evaporated water and bringing it up towards the areas that feed the rivers that feed the falls. This area is known as a watershed and it is hundreds of thousands of square kilometers big. All the tons of rain that falls in that watershed all eventually flows over the falls. The rivers are also constantly fed by groundwater. All the rain that got absorbed into the soil sinks down and flows underground. Sometimes it reaches a point where the weight of the earth pushed it back up through the earth creating a spring. That spring will feed a wetland or stream that will flow to the falls. In the end it is still just every drop of rain that ever falls in that watershed eventually making it over the falls.",
"A waterfall is not much different than the rest of the river. Rivers run horizontally, and a waterfall is a vertical section of that river. Niagara Falls is a 0.051 km vertical section of the 54 km long Niagara River. So, the question is less about why the Falls keeping falling, but why the River keeps run, since the rest of the river has much more water. The answer to that is the water cycle. Niagara falls is fed by Lake Erie, which is fed by lake Huron, which is fed by lakes Michigan and Superior. So, it has a fairly large water supply. Those lakes stay full because of rain. Water from various places evaporate, and then fall in the lakes. If the water does not fall directly in the lakes, it falls in areas where the water will drain into the lakes. Also, a bunch of snow falls on the ground during the winter. When this snow melts in the spring and summer, it drains into the lake as well.",
"Because rain flows in to lake Erie keeping it full. It flows down the falls in to lake Ontario, then eventually in to the ocean. That's why other rivers also don't run out of water.",
"It will eventually run out, as the Great Lakes’ watershed is only like 1% renewed annually... but the Great Lakes (Superior, Huron, Michigan and Erie) that feed the Niagara River are absolutely massive. I believe they hold close to a quarter of the entire planet’s freshwater. If flow rates over the falls stay the same (which they do control, monitor and limit very closely now to ensure diversion to power generation/utility consumption is fair and not drying it up), part of the falls could disappear in 2,000years. Even if these falls have a never ending source of water, the other thing is that the falls’ location is eroding further upstream over time. Although man made intervention could slow this down, the forces of erosion are pretty constant and it will eventually run it all the way back to Lake Erie (in ~50,000years) to turn it into more of a series of rapids versus the massive falls that exist today. Found most of this info here: URL_0"
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m09952 | What is long term effects of vaping vs smoking and why is it so hard to quit nicotine? | Biology | explainlikeimfive | {
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"Well, we know that the long term effects of smoking are lung cancer, asthma, tar in the lungs, etc. Very not good. Unfortunately, the longer term effects of vaping are not as well documented. Largely due to mainstream vaping being relatively new in the cultural zeitgeist, if not new technology completely. It *seems* like vaping is still bad, but we don't have large longitudinal studies to say for sure. As for why nicotine is so hard to quit, it's addictive. It activates habit areas in our brain to make you repeat the action that gave you nicotine the first time. This is true whether or not it's smoked, vaped, or put on a pad."
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m09ek2 | Why isn't Malcolm X taught and popularized as much as Martin Luther King. | Other | explainlikeimfive | {
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"Martin Luther King Jr.'s more conciliatory approach to civil rights advocacy is far less threatening to white America, which then translates into which one is focused upon in American history classes. Plus the fact that he was assassinated made his story more \"dramatic\".",
"Unpopular opinion but people despised Martin Luther King just as much as Malcom X. The problems was that black people were being treated inhumanly and wanted equality under the law. King is easier to teach in school because he believed in peaceful protest...Malcom X was more radical in his views. I say King was despised just as much as Malcom because he was killed despite his calls for peace and unity."
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m09mqd | Uniformly continuous (real analysis) | I'm looking at the definition and can't wrap my head around | Mathematics | explainlikeimfive | {
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"In simple terms: if x and y are very close, then f(x) and f(y) must also be very close for a uniformly continous f. There exists a distance between x and y that brings the difference between f(x) and f(y) below some arbitrary limit epsilon (as small as we want) In practise that means that the function has no infinite values, and no infinite slopes anywhere. Typical counterexamples are 1/x (infinite value and slope at values close to 0) and the heavyside function (infinite slope at 0, if x is positive and y is negative then no matter how close you put them the difference between f(x) and f(y) is always 1 so we can't make it as small as we want)",
"The opposite would be (guess) continuous by chuncks. Take a pen. Can you draw a single line from left to right that follow your function? * Yes, it's uniformly continuous -- cos(x) * No, It's not uniformly continuous -- 1/x * If you can't draw a line for part of the region, then it's not even continuous (don't have an example for that one) PS: I tried to be as ELI5 as possible, but I might be wrong given it's not my native language, and especially for mathematics, word carry precise meaning.",
"The first time I ever learnt about the definition of uniformly continuous I couldn't understand the difference with the definition of continuity. Let's see both definitions and we will try to understand what do they mean and why they are different. The definition of continuity is as follows: > A function f is continuous at a point *a* if given ε > 0, there exists δ > 0 such that if *x* is a point satisfying |*x* - *a*| < δ then |f(*x*) - f(*a*)| < ε. What this definition is saying is that a function is continuous at a point *a* if you take *x* close to *a* then f(*x*) will be close to f(*a*) (if the distance from *x* to *a* is less than δ then the distance from f(*x*) to f(*a*) will be less than ε). There are two key things in this definition: First one is that the choice of δ will depend on ε (I think it's obvious because if you want f(*x*) and f(*a*) to be very close (ε) then *x* and *a* will need to be very close (δ)). The second one is not that obvious and it is actually the key to uniform continuity: δ will also depend on the point *a*. This is very important so let's look at this example: Consider f(*x*) = *x*^2 which you should know is continuous at every real number *x*. Consider two points *a* = 0 and *b* = 200. For the point *a* let's consider the point *c* = 1 (which is 1 unit away from *a*). Then, f(*a*) = 0^2 = 0 and f(*c*) = 1^2 = 1. So we get that f(*c*) - f(*a*) = 1. Now take *d* = 201, and now we get that f(*b*) = 200^2 = 40000 and f(*d*) = 201^2 = 40401 and thus f(*d*) - f(*b*) = 401. In both cases we took points which were 1 unit away. However, the distance between their images varied a lot. So if we want to find points whose images are close to f(*a*) we need to get points which are somewhat closet to *a*. But if we want to find points whose images are close to f(*b*) we need get points which need to be really close to *b*. In fact, if you want to find a point e whose image is 1 unit away from f(*b*) you'd need something smaller than *e* = 200.0025, which is 0.0025 units away from b (compare it to a and c, which were only 1 unit away). Now we know that δ depends on ε (how close we want the images to be) and on the point *a* (as shown by the example), let's look at the definition of uniform continuity. > A function f is uniformly continuous if given ε > 0, there exists δ > 0 such that if *x* and *y* are points satisfying |*x* - *y*| < δ then |f(*x*) - f(*y*)| < ε. I'll be honest, the first time I saw this definition I couldn't see the difference, but they are *very different* although very subtle. In fact, if a function is uniformly continuous then is continuous. What's the difference, then? Can you see it? The key is in the first definition, given a point and ε you find some δ, which might only works for that point as we showed (by the example: the first two points were 1 unit away and their images were 1 unit away, but even though the second ones were also 1 unit away their images were 401 units away), whereas in the second one, given ε **there is a δ which works for every two points**. Quote from Wikipedia: > Thus for continuity at each point, one takes an arbitrary point *x*, and then there must exist a distance δ [...], while for uniform continuity a single δ must work uniformly for all points *x* (and *y*) [...]. [Here's the link]( URL_0 ). By the way, the term *uniformly* comes from the fact than in standard continuity, each point will have it's own δ but in uniform continuity there is a δ that will work for every point, making everything uniform (you'd only need a single δ). Consider the function f(x) = 1/x defined on the open interval (0,1). This function is continuous but we will prove that it's not uniformly continuous: Let ε = 1. Our question is: Can we find some δ > 0 such that if two points verify |*x* - *y*| < δ then |f(*x*) - f(*y*)| < 1? We will show that no matter what δ > 0 you find, there will be two points *a* and *b* such that |*a* - *b*| < δ but |f(*a*) - f(*b*)| > = 1. In fact, consider *a* = 1/*n* and *b* = 1/(*n*+1) (where *n* is a positive integer). You can show that *a* -* b* = 1/(*n* *(*n*+*1*)) which goes to 0 as *n* goes to infinity. So given δ > 0 there will be some integer *M* such that 0 < a - b < δ as long as we take *n* > *M* (I hope you can see where this comes from). However, f(*b*) - f(*a*) = f(1/(*n*+1)) - f(1/*n*) = *n* + 1 - *n* = 1 > = 1. So this function is continuous in (0,1) but not uniformly continuous. There is a theorem that if your function is continuous and is defined on a closed inteval [a,b] then that function is uniformly continuous. The idea is that for ε > 0 every point will have it's own δ > 0, but unlike 1/x, because continuous functions on closed intevals don't go to infinity, there must be a minimun δ. And because each other δ will be bigger, such minimun δ will work for every point as well (if points being less than 1 unit appart works, then points being less than 0.0025 units appart will also work because 0.0025 < 1) so you just proved that for that ε and for that minimum δ you have precisely what uniform continuity states."
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m09teb | What actually happens to the human body when an explosion happens in close proximity? | Honestly, I'm watching a war movie and a dude got hit by an IED. It got me thinking though, and I don't quite get what is the lethal factor in an explosion? There always seems to be fire in the movies, and it's clearly a lot of force. But my question is what ACTUALLY happens to (I guess anything) that gets hit by a large bomb/explosion from a play by play/physics situation? I feel like this is kinda dark, but I just had one of those curious moments and felt like this was the appropriate place to ask | Physics | explainlikeimfive | {
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"For conventional explosions heat doesn't matter much. The main lethal factor for people are flying debris (wich is why anti-personnel bombs contain some extra) Aside from that the involved pressure hits verye harshly, depending on the size and distance of the explosion it can range from \"topple you over and hit your head\", over \"punch in the stomach that causes internal bleeding\" to \"your bodyparts are ripped apart\"",
"The fire is just for the benefit of the movie. Movie explosives tend to include a lot of gasoline or other fuel to get that nice big fireball. With the exception of weapons that are designed to create fire, real-world war explosives don't care about fire. When an explosive weapon goes off, it essentially releases a whole lot of energy at once. And this is weaponized in two main ways. There's going to be a massive pressure differential as the explosive's energy 'pushes' the surrounding air aside. This pressure wave is so powerful that it'll pretty much rupture the soft parts of your body if you're unfortunate enough to be in the blast radius. Even if your body manages to stay in one piece, it can just squish the soft bits like your organs. Most explosives are also designed to produce shrapnel. Shards of the bomb's casing, objects like nails that were packed in with the bomb. A hand grenade has that pineapple pattern just to create more surface are and thus more shrapnel when it explodes. Shrapnel goes flying in every direction pushed by that pressure wave, that energy release when the bomb goes off. And it will shred anything nearby. It will cut through bodies, sever limbs, go straight through light materials like car paneling. And of course, since bombs are weapons, most are designed to achieve specific things. Some landmines are spring-loaded so they jump up to chest height before exploding. Vehicle mines are often shaped in such a way that they guide most of the explosive force upwards into the vehicle above instead of exploding equally in all directions. Anti armor munitions often have staged explosions to help them penetrate armor before doing something nasty to the crew inside a tank. Thermobaric bombs are designed to create a long-lasting explosion that uses up all of the oxygen in an area, rupturing the lungs of anyone unfortunate to be in the very large blast area. It's perfect for clearing out caves and tunnels where direct shrapnel wouldn't hit people. But the basic idea is that explosives produce a devastating pressure differential compounded by shrapnel.",
"The most lethal part of an explosion is the pressure change. Since the human body is more or less a bag of organs, getting caught in a high pressure area very suddenly tends to squish things, particularly organs that aren’t internally supported well, like the lungs. Depending on the explosive other factors can make a difference, such as shrapnel or heat. [Here]( URL_0 ) is a video comparing the likelihood of surviving a grenade on land compared to underwater, which might answer things a little better."
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m0be9c | Is the explosive force of blackpowder linear? Exponential? Or does it level off? | Physics | explainlikeimfive | {
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"The energy released is linear. The \"force\" of the explosion is dependant on geometry (if you don't seal it off it just burns without explosion) and how much you compress the powder though."
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m0bsyw | What does it mean that Google won't allow third party cookies in Chrome? No more third-party analytics firms collecting data on me while using Chrome? | Technology | explainlikeimfive | {
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"No more third party analytics firms collecting your data *through cookies*. There are a bunch more ways they can identify you though. Also third party basically means \"anyone who doesn't have a contract with google\" wich is basically just them receiving a monopoly on your data"
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m0bykg | Why do people who are actually strong look different than bodybuilders who train all week? | Biology | explainlikeimfive | {
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"Bodybuilders go through a period of \"cutting\" before contests. They reduce their caloric intake dramatically, down as low as they possibly can, so they lose a ton of weight and appear really \"cut\". Ironically, they're at their weakest during competitions. They train specifically for aesthetics. Strongmen keep a protective layer of fat to help resist injuries. They train for all-around strength, so they aren't worried about \"looking good\".",
"Competing bodybuilders are usually strong as fuck. Not as strong as powerlifters/strongmen whose whole sport is being absurdly strong, but they move a lot of weight. The main difference is the layer of fat. Look at a bodybuilder in the offseason when they're bulking up and they can be hard to tell apart from the heavyweight strength guys. The other difference is in what muscles they prioritise - bodybuilders emphasise the stuff that makes them look even bigger than they already are (so lots of lats and shoulders to make themselves look wider, not so much abs and obliques because that would take away from that appearance of wideness), strongmen emphasise the ones that help them move heavy weight (so lots of ab/oblique work because a thicker, stronger midsection helps if you want to have 1000lbs on your back and not break) but there's a hell of an overlap between the two.",
"To build on what the other user was saying about strongman and fat, Bodybuilders are actually strong, but they train in different rep ranges and with different movements. They focus on higher repetition to maximize muscle growth and isolate lagging muscles, rather than training 1 to 3 reps on big movements most of the time, which maximize muscle recruitment. If a power lifter and a body builder had a bench press competition, the power lifter will have a higher 1 rep max, but the bodybuilder will likely have a higher 10 or 15 rep max due to specificity.",
"To continue upon other's content, functional labor doesn't make you look strong. It just makes you strong. Example: I spent a full summer picking up things that weighed around 100 pounds. All day, every day. I was on heavy crew. In the course of a day, I'd lift an odd sized object weighing about 80 lbs about 1,000 times a day. I was strong as hell. It was a pot yard nursery so I was working 10 gallon which are soaked in and there's a big ass tree in it as well. They are heavy and awkward. By the end, I was lifting them like picking up a cat. I went back to the gym when college was back in session. I had no problems moving 100lb weights with one hand and setting them. It was like picking up a box of cereal to me. Then I went to do some bench curls. I was no stronger than before. I could pick up 250 lbs to my chest like it was nothing, but I still only curled 70 lbs on a bent bar. Bottom line, the pretty muscles don't seem to do any real work. The big muscles take the weight. Also, your own mass makes a difference. You don't get skinny when you do heavy labor. You have a gut that looks like fat but it's all muscle. It ain't pretty, but you need it. You also need the fat for energy when you're really working hard. I've lost 4 lbs in a day from heavy labor. Granted, that's mostly sweat, but the fat gives you reserve energy. Without the reserve, you'll tank out.",
"Strongman have more fat. Bodybuilder try to go as low in fat% as they can. They also tend to train different. But you have strong bodybuilders and strongmen who look like bodybuilders. Look at old video's of Ronny Coleman. He's lifting insane amounts of weight. Look up \"Mariusz Pudzianowski\" in google image search. He's looking like a bodybuilder despite being a strongman."
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m0depv | Why is brain size not equivalent to intelligence? | Biology | explainlikeimfive | {
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"Brain size helps, however the key is the number of connections in the brain that is the key to intelligence.",
"Between humans or humans and animals? With animals it's easy, the brain isn't one big lump of thinking power it's comparmentalized, the is a thinking bit, a smelling bit, a hearing bit, a moving bit ... and in animal the thinking bit is rather small, they might have great bit smelling bits though. From human to human, the difference is more subtle. Even thinking bit size doesn't correlate to intelligence, brcause it's more about how many connections you have between brain cells and in what way they are connected. You can imagine a pazer with 100 points on it and each point is connected to two others, and then imagine a paper with 90 points but each of them is connected to 5 points. The second page is almost completely covered in ink. That's the difference between a big dumb brain and a small claver one. And also the dots aren't interchangeable, you could have many complex connections between the mathematical, logical, thinking out of the box dots and be Einstein, or between the spacial awareness, hand-eye-coordination and balance dots and be Lebron James. Both would be powerful brains, but you only call the mathematical one intelligent, the athletic one would be called talented or something."
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m0dfpc | Why does hot water take dirt off dishes so much easier than cold water? | Chemistry | explainlikeimfive | {
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"Heating water increases molecular activity. Warm liquids always dissolve things faster than cold. Hot liquids even faster. The agents that bond food to dishes are usually starches, sugars and oils. In hot water starch bonds relax, sugar crystal liquefy and oils move from solids back to liquids. Edit: Not all liquids and not all \"things\". I was referring to stuff in the average household setting!",
"1 Hot stuff have their atoms move around faster. This results in them hitting the dirt harder, resulting in it dissolving faster. 2 For fairly complicated reasons solids dissolve better into hotter liquids (and gas the reverse dissolve better in cold liquids). 3 Additionally when you have certain solids to clean (e.g. fats) they tend to become more liquid like as they are heated up resulting in them not sticking to the surface as hard and are easier to wash away. Theses three factors together result in dirt being taken off much better by hot liquids.",
"To understand this, we need to talk about molecules. Molecules are the smallest thing that's still the same thing. You can divide a cup of water in half, and the two halves will still be water. If you cut a water molecule in half, you don't get two even-smaller waters. Molecules are tiny. Molecules in liquids and some solids tend to slightly stick to each other. Sometimes one molecule will have parts of it that are friendly with one kind of other molecule and a different part that's friends with a completely different kind. Soap is like that. It's friends with both water and fat. Let's say that there's a plate (ceramic) molecule and their friend, a fat molecule. They're holding hands but you want to break them up. Should you send them to a ballroom (cold water) or a mosh pit (hot water)? People move a lot faster and more violently in the mosh pit, so that's the best bet. In the same way, the molecules that make up fat are pulled away by hot water, whose molecules are vibrating faster than cold water's. Water isn't very friendly with fat though, so hot water alone doesn't work great. It works even better if fat's clingy, moshing friend, the soap molecule, grabs a hold of both the moshers and fat and pulls them away into the crowd.",
"Follow up question: Have you been eating dirt?",
"Sinner's Circle. Heat, detergent, time, and agitation all play a role in cleaning. Adding to any of them increases cleaning effectiveness. The other answers in here talk to the specifics of heat, but it's an interesting topic to read up on, and that search term should give good information."
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m0e3j8 | Why we cant "park" satellites and space station in Lagrange points, to avoid drag? | Physics | explainlikeimfive | {
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"We can and do. Lagrange point 1 is between the Earth and Sun and has the [Solar and Heliospheric Observatory]( URL_1 ) parked there. L2, on the opposite side of the Earth, has the [Gaia satellite]( URL_0 ) parked there. The other points are much further away and I'm not sure if we use them.",
"We can and we have done that. Multiple satellites have been placed in the lagrange points around Earth. The James Webb Space Telescope will be placed at a lagrange point. We don't put space stations there because none of the benefits of doing so are really useful for a space station and it's much more beneficial to have it be in low Earth orbit so it's easier for resupply missions and such to reach it. The lagrange points aren't close.",
"We can and do park man made objects at various Lagrange points. The reason for parking satellites there has little to do with drag however. Drag from the thin atmosphere slows satellites and space craft in low earth orbit down a bit because they are so low to the ground. Space \"officially\" begins by most definitions about a 100 km high up. that is about as far as you can reach in a car in an hour if it were vertical instead of horizontal. The International Space Station is about 400 km high up. (A distance about equivalent to what a high speed train travel in a hour and a half or maybe a hour and a quatre) This is not very far either, enough of our atmosphere reaches that high that the ISS gets slowed down looses a bit of orbital height to drag and has to be boosted up again regularly. The Lagrange point between the earth and the moon, is most of the way there. about 320000 km. ( This is a distance equivalent of about 10 days worth of travel at the speed of sound.) My point here is that the Lagrange points even the closest ones are a whole lot father away than al the other stuff we normally put into orbit. The one between the earth and the moon is closer to the moon than to the earth (about 85% of the way to the moon). At those distance from earth drag from the atmosphere no longer really matters. This does not mean that stuff put there will not need to do station keeping at all. 3 of the 5 Lagrange points are inherently instable and the other two are still not perfect. For one thing other stuff may get trapped there like dust and even some captured rocks in some systems. For another thing the Lagrange points in the earth moon system get disrupted by the gravity of the sun quite a bit over time. You will still need to spend some fuel if you want to stay in some of those places for a long time. That being said, stuff put there tends to stay put much better than in most places. It also tends to stay put in relation to the other objects in the system in ways that no other place will easily allow. The Lagrange points in the earth moon system will always be in the same place in relation to the earth and the moon and since the moon always shows more or less the same face to the earth, any object in an Earth moon Lagrange point will be stationary in the sky above the moon. Similarly the Lagrange points in the sun-earth system are fixed between those two bodies, which comes in handy if you want to put a satellite somewhere where it can observe the sun without the earth getting in the way. Additonal fun fact: Some Lagrange points in our solar system have accumulated quite a number of natural objects over the ages. The L4 and L5 points of the Sun-Jupiter system are so full of asteroids that we have even developed a system for naming the biggest ones. The asteroids surrounding the points are named after heroes from Trojan war. With the ones at one point named after the defending Trojan heroes and the ones at the other named after invading Greeks. Due to a minor mistake early on before the naming system was ironed out the asteroids named after Patroclus and Hector were named at the wrong Lagrange point and rather than renaming them, astronomers have simply decided that they must be 'spies' in the enemies camps to keep the logic of the naming system intact."
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m0e71g | What is the difference between digital and analog audio? | Technology | explainlikeimfive | {
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"OK, here's a really ELI5: Sound travels in waves. Tie a jump rope to a fence and wave it up and down; the shape of the rope will resemble a sound wave. Now imagine you could freeze time, and you wanted to build a copy of the rope's shape, but you only had bricks. So, you take your bricks, and start to stack them up under the rope. Some times you'll only need a couple of bricks; sometimes you may need to pile them up 10 or 12 high to touch the rope. After a while, if you step back a bit from your work, you can see how the piles of bricks look *very much*, but not exactly, the shape of the rope. The rope is the \"analog\" wave form, while the bricks are the \"digital representation\". The analog wave is *continuous* - the rope's height above the ground can have any value between, say 2 inches and 4 feet. The digital representation is *discrete* - it can only be 1, 2, 3, 4, etc. number of bricks. It can't be 3.867 bricks. Analog systems capture the continuous wave. The groove in a record - do 5 year olds even know what those are anymore? - is a long continuous wiggle that copies the original sound wave. This is actually fairly simple to do - the first records were made of wax, with the platter rotating while a needle, driven by a microphone, made the groove on the surface. This is an analog to analog process. Digital systems try to recreate the original wave by using standard sized pieces to fill in the space beneath the wave, just as we did with the rope. But how wide, and how tall, should each of these pieces be? This is beyond ELI5, but there was a smart guy named Nyquist who figured out that to completely capture all the information in the original wave, it needs to be sampled at twice its highest frequency. This tells us how \"wide\" the bricks need to be. For example, if the highest frequency in the wave was 4000 cycles per second, then we would need 8000 samples, so our 'bricks' have to be 1/8000 of a second wide. The height of the bricks are is a function of how many digital bits in each brick. If you use 8 bits, you can get 2^8 = 256 levels. If you use 16, you get 2^16 = 65,336 levels. If you use more bits, it makes the bricks less high, so you can squeeze the brick piles closer to the actual wave, and so sound more like the original. Note the digital process requires an analog-to-digital conversion at the input, and then a digital-to-~~audio~~analog conversion at the output. There are some - Neil Young comes to mind - who believe that this distorts and ruins the original recording; others don't notice it. finally, and this is way beyond ELI5, digital techniques like Adaptive-predictive Pulse Code Modulation (ADPCM), use clever math and engineering tricks to get the sound even closer to the original, while using less bandwidth. EDIT: Thanks for all the kind comments and awards. Thanks also to those who corrected the minor errors, and expanded on some of the stuff I left out. EDIT EDIT: To all the longitudinal wave fans. yes, you're right. So am I. A sound wave can be represented as a two-dimensional signal on an oscilloscope, and it was that representation I was referring to. I elided the silly scope reference because it's ELI5.",
"Analogue audio is stored in an analogue (continuous) medium such as vinyl or magnetic tape (audio cassette). Digital is stored in a discontinuous medium such as a CD or MP3. Sound is a wave, so audio information just describes the shape of the wave. On vinyl there is a wavy groove which has that shape, on cassette there is a varying magnetisation of the tape which also has the shape. ~~On a CD the \"height\" of the wave at each moment in time is assigned a value from 0 to 255~~ *~~65535~~*~~. Then at the next timestep it has another value. So the true wave shape is approximated by a sort of stepped shape. See a comparison~~ [~~here~~]( URL_0 )~~.~~ *A digital signal on a CD stores the wave form as a series of values at moments in time, with those moments very close together. Think of a series of dots where if you squint you see the original curve. There are 65536 possible values, stored every 1/44100 seconds, which is all you need to replicate the original sound when you play it back.* So long as there are enough values ~~and short enough timesteps~~ the digital shape is a close enough approximation to the true shape that no human can hear the difference. MP3 and other digital formats go further and compress the audio, so they sort of describe the shape rather than simply approximating it as outlined above. This can lead to distortions that humans can hear (or claim to). You might think that analogue is therefore 'perfect' in a way that digital cannot be. This is sort of true, but any real analogue medium will have physical limitations which add their own distortions to the sound, potentially to a greater extent than good digital audio. *Edit to add: yes I am aware that a digital signal perfectly replicates the waveform up to the desired frequency, thanks for all the reminders.* *Edit 2: alright alright I get it. People have strong feelings about this analogy.* *Edit 3: actually scrap that I stand by my statement that a digital audio signal is an approximation of the original. Sound is not band limited, and does not have finite bit depth.*",
"Analog audio is a continous wave, digital it’s like taking little pictures of the wave, that make it discrete. But there is too much pictures so in most cases you can barely notice the difference.",
"Analog is wiggles. Digital is numbers that say how big and how fast to make the wiggles. Speakers wiggle the air which wiggles your eardrums. So either way, the end result is wiggles. Digital is nice because if you see a messed up \"5\" it can be easy to see it was supposed to be a \"5\" because you know what 5s are supposed to look like. (Real digital signals use binary, but the concept is the same.) But if a wiggle gets messed up, it just looks like another wiggle. So you can't fix errors as easily with analog. This means analog is more susceptible to noise. Digital requires conversion back to analog to make the wiggles for the speakers. Having to convert back and forth is the downside with digital. The faster the wiggle changes, the more numbers per second the electronics have to convert. But modern tech has no problem doing this with wiggles that only change as fast as audio does.",
"Analog is wavy air, and can be stored as wavy grooves. Digital is 1s and 0s. When you want to listen to digital audio, it gets turned into wavy air again first so you can hear it.",
"Here is electronic music pioneer Wendy Carlos on the different between digital and analog audio: \" Digital, of course, is essentially computer data which accurately describes an audio signal. It's easily manipulated and can be copied exactly -- all those ones and zeros, you know. Analog is how we usually describe sound waves, a continuous change of pressure or an electrical signal, what a microphone produces, what we used to record on tape. It's a much riskier way to handle audio, but historically was the method we first discovered. Between the two, don't look for deeper meaning or arbitrary differences. There is a cult of near-religious dogma that proclaims analog sound on LPs (\"vinyl\") to be perfection (what a hoot that is for those of us who used to cut LPs for a living!). They think you have to use special wires and elaborate techniques they don't even understand, and they claim that digital is in cahoots with Lucifer. It's kind of pathetic, based on ignorance and flamboyant cheek. The simple answer for synthesizers or reproduction is: To the listener, it shouldn't matter at all, as long as it sounds fine. If you're a performer, it shouldn't matter at all. If you have a very advanced analog synthesizer and then you have another that is all digital--and you get a lot out of both--fine, use them. On the other hand, digital can, in principle, let you be more precise, with finer finesse and control. Analog runs out at five significant digits of accuracy (it doesn't have infinite resolution), something like that, and there's tape hiss to contend with. If you want to put the money and time into it, you can obsess with digital until you're dead. It's a potential that hasn't often been tapped, but usually you reach a practical limit, there's life for you. Microtonal tunings are a breeze with digital synthesizers, but very hard to do with analog.\" From: [ URL_0 ]( URL_0 )",
"Drawing a wave using Lego vs Pen. You can get more accurate interpretation of the wave using regular lego vs duplo (frequency/sampling)",
"I guess you mean analog and digital recording of audio. Sound is vibration of air (or any medium it travels through). Its properties are frequency (how many oscilations it makes in a second, i.e. how high the tone is) and amplitude (how 'big' are those oscilations, i.e. how loud it is). So, how to record that? In essence, there are three ways: vinyl records, magnetic tapes and digital. Vinyl is the simplest one. Imagine a big membrane that is in the way of those vibration. From the air, the vibrating transfers to the membrane. Now connect a sharp needle to it so it vibrates too. And while vibrating, that needle leaves the marks on a rotating dics. Then you can go reverse and the needle follows the grooves on the record, vibrate, transfer vibrations to the membrane and then to the air so we hear the recorded sound. Sure, this is oversimplified but it shows the important part. Tapes work similarly, but the membrane is not connected to a needle but to an electromagnet. Magnets and elecrticity have a love relationship. When a magnet moves near the wire coil it creates electricity in in. And vice versa, if there is electricity in a coil, the magnet will move. So, as the magnet vibrates it creates a small amount of electric current that magnetizes the small particles of iron oxide on a moving tape. What was a wiggly scratch on a vinyl is now a series of variating little magnets of different strengths. You play the tape by reverting the process: tiny magnets on tape create the electricity in the electromagnet in the tape-player head, which moves the magnet connected to the membrane which creates the sound. Both these systems transfer physical properties of sound into some other physical properties - depth and width of scratch mark on the vinyl or strength of magnets on tape. Now the digital recording... which also goes from the membrane and into electromagnet to transform the vibration into electric current but then that current get measured and stored as a number. As the sound is vibration that changes many times a second (it goes from 16 to 20000 oscilations per second) it has to do quite a lot of these measurements and store a number for each one. For CD it is 44.1 thousand per second, film standard is 48000 and, more often than not, initial recording in profesional environment is 96000 times per second. Difference between this and the previous two ways is that now we don't have one physical property transfered into other but into a series of descrete numbers somewhere in memory of the computer. To store them permanently, you can enrave them into silver foil (CDs and DVDs) or use magnetic disks (hard drives). Magnetic disks use the same mechanism as the audio tapes but they don't record the vibrations directly but the numbers created according to those vibrations. So what's the benefit? (edited this paragraph as it was badly formulated) Magnetic tapes and disks are losing a tiny portion of quality with every reading/listening. Here is the important difference. If you copy analog data from the tape, there will be more and more shhhhhh noise introduced in every new generation of a copy as the electricity makes noise. But the copying of a digital recording is immune to that as each new reading and copying gives the same series of numbers as the original even if the recording is faded or partly damaged. That is because even as the magnetic material wears off, reading of the numbers is the same and when you deal with numbers you have safety mechanisms to check if your reading is ok or even to recalculate a part that is missing (see checksums for more info on this). But eventually the hard disk will fail.",
"Analog looks like the thing it represents. In this case wavy air is replicated by wavy grooves on vinyl, or wavy magnetism on a tape. Digital turns things into numbers. In this case the wavy air is measured at various points and the numbers stored in binary reflective areas on a CD or electrons in flash storage.",
"Audio engineer, here. Something I can finally contribute to on this sub! [This article]( URL_0 ) does a really good job describing the basic process in a straightforward way. \"No matter which recording process is used, analog or digital, both are created by a microphone turning air pressure (sound) into an electrical analog signal. An analog recording is made by then imprinting that signal directly onto the master tape (via magnetization) or master record (via grooves) . . . Digital recordings take that analog signal and convert it into a digital representation of the sound, which is essentially a series of numbers for digital software to interpret.\" **Where an analog recording is similar to the fluency of film, a digital recording is stop motion photography.** Analog audio is an exact representation of the sound, whereas digital audio captures bits and pieces of the signal in ones and zeros (binary). This makes it seem like digital audio is inferior from a sonic standpoint (~~spoiler: it is~~), but digital audio has advanced to a point where the difference is negligible or even unnoticeable to the trained ear, with the exception of a few scenarios (namely heavy gain). Edit: it is my **opinion** that analog audio/equipment sounds better than digital.",
"Analog sound is the ripples on water when you drop a stone into it. They are a physical representation on a medium. Digital audio is a mathematical representation, but done at such resolution that when when played the human ear hears it as clear sound. The current formats and sample rates we use nowadays actually reach the limit of human hearing and our audio equipment. But yeah. Analog is basically a drawing or carving of the sound on a medium. While digital is a mathematical representation when resolved makes the same drawing",
"Actual ELI5 attempt: Analog audio tries to recreate an event using a continuous signal. Digital tries to recreate an event by chopping it in tiny pieces and putting them together again. Think about tying a rope to a post and shaking the loose end - you got a moving curvy rope. Digital will chop the rope into bits and then make a shape like a rope - you get a picture of a curvy rope.",
"Analog is continuous and digital takes little samples. It's like cooling at a picture vs a mosaic. The higher the sample rate of the song the smaller prices you are using for the mosaic.",
"There are some incorrect explanations in the comments here. [A digital signal has the same resolution as the analog to digital converter originally encodes]( URL_0 ). There is no data loss due to \"stepping\" or \"discreteness\" of the digital signal. That video is somewhat technical but has an accurate explanation of the differences- and surprising similarities- between digital and analog signals.",
"The main difference is how the two formats are stored. A digital track is recorded through a computer and played from a CD. Analog is recorded on a physical format and the two popular formats were tapes and vinyl records. Digital is much more clear to make out, while analog is a bit \"hissy\" or \"crackly\" depending on the format a song is being played from. It's also good to note here that analog formats deteriorate from dirt or overplaying, so the typical home record would sound worse than the original studio recording.",
"People here quoted shannon nyquist theorem to say that digital can always replicate analog up to a certain frequency limit perfectly. this is not necessarily true. shannon theorem only answers the 'discretization' problem in analog-digital conversion. in shannon theorem, to perfectly recreate the original signal, perfect(accurate) samples of the original waveform is required. in fact, shannon theorem still assumes continuous amplitude of the sample and only deals with the discretization of time. to argue perfect analog/digital conversion with only shannon is somewhat misleading in my opinion. in practice there is another factor called 'quantization' error. this error is present during the amplitude conversion of analog data to digital and vice versa, due to imperfections in the electronic circuit. due to the presence of this error, 'perfect' digital samples of the original waveform cannot be obtained and the recreated waveform will always be slightly different from the original. this has nothing to do with shannon theorem and is only dependent on how accurate the electronic circuit can quantize the amplitude of the original waveform during the sampling process EDIT if i may add, i think the main difference in digital an analog audio is how the data is treated in the player/recorder. soundwaves are analog signal, and generally microphones and loudspeakers can only deal in analog domain to convert the soundwaves to electrical signals and vice versa the data flow in analog audio is: soundwave(analog)- > microphone- > voltage(analog)- > storage(analog)- > voltage(analog)- > loudspeaker- > soundwave(analog) while in digital audio the data flow is: soundwave(analog)- > microphone- > voltage(analog)- > ADC(sampling)- > voltage(digital)- > storage(digital)- > voltage(digital)- > DAC+LPF(reconstruction)- > voltage(analog)- > loudspeaker- > soundwave(analog) as you can see analog audio is much easier to implement since everything is continuous while digital audio is more complex since it requires data conversion schemes. at the output of DAC, the voltage still has a 'stepped' shape, however due to the effect of LPF characteristics of the following stages(amplifier,etc.)the voltage waveform shape is 'smoothed out' close to the original waveform since the high frequency components are eliminated.",
"I think it's useful to understand the context of why you are asking, as there's something that I think the other answers, which are technically correct, miss. The sound you HEAR is a waveform, always. The device producing the sound waves is \"Analog\" depending on your specific definition of the word and the context. Most of the time this stems from some argument or need to figure which is \"best\" digital or Analog. If we accept that sound waves can be represented by a 2d graph that plots the sound pressure exerted on your eardrum, this is an anlog of that sound wave. If we are talking recording formats, the term Analog has a more literal meaning as well especially in the bygone age of physical media. A vinyl record, like an LP, is a literal, physical analog of the original sound wave. In the groove there are tiny peaks and troughs that that match what the sound wave looks like on that 2d graph of the pressure exerted on your ear drum. It's reproduced by a needle tracing over the physical groove. An amplifier takes the signal from the needle and increases the sound pressure, amplifying the signal. It's possible to do this on purely mechanical level, I.E gramophones, or using electricity. In an electrical system of amplification, the needle is connected to a device that creates a very small voltage when you move it up and down. A speaker that you hear sound from typically requires a great deal more voltage than the needle devices generates, so the amplifiers job in this case is to increase the voltage of the signal from the needle. A speaker is usually considered \"Analog because of the kind of device it is. It is an arrangement of electromagnets that moves the core based on the input voltage. The cone of the speaker is attached to the core of the magnet and produces a sound wave by the cone moving air. The input signal is a constantly variable electrical signal that is faithfully and directly reproduced by the movement of the core. This wave is always sinusoidal in nature. What you hear from the speaker is a sound wave that closely resembles the wave that the records physical \"Analog\" was originated from. In the case of an electrical system like I just described, if you measured the voltage over time at the needle using an oscilloscope you'd see a weak electrical signal, but it would be very similar to the peaks and troughs as the original record. If you then measured the same voltage over time at speaker, it's again a very similar wave as the needle one, and the record one, u this time with a much higher voltage. All sounds simple right? The reason I said SIMILAR wave and not SAME wave is that at each point in the process, noise is introduced. When the record was made, some noise is inherent in the process of doing that. When the needle devices changes the up down movement to voltage there is noise induced into the signal. When the amplifier takes the sound and increases the voltage, more noise is introduced. I'm going to skip over tapes a medium, but the brief story there is that a tape is an analogue of an original wave that uses magnetisim rather than a physical representation as found in a vinyl record. So then along comes \"digital\" processing. Digital equipment doesn't deal with variable state. This is because it's what is known as solid state. Different voltages mean very little to solid state devices. It knows only ON or OFF Not going into that here, but that's where this term come from. In operation, you know the device is either on or off. Speakers are really the opposite of \"solid state\", in operation they might be any almost infinitely variable. They need a voltage that is constantly variable, to produce a reproduction of the original recording. If you store something digitally, at a fundamental level it is all just 1 or 0 in terms of value. The difficulty is, if you want to store a signal that is a constantly variable wave and then reproduce it on a speaker that needs a sinusoidal wave to produce sound, with devices that only know 1 and 0. Well, let's deal with storing the wave first. A microphone is basically like the needle on the record but in reverse. It's a diaphragm attached to a similar device that when you speak to it, it creates voltage. This gives you the original, electrical Analog of the sound wave you want to store. What you do with your digital device is sample the voltage value of the wave produced by the microphone at specific, repeatable points in time. This is referred to as sampling rate. When you do this, you can imagine you don't get a smooth sinusoidal curve, you actually get something resembling a load of steps, but if you trace a line through the centre of each step, you get something that approximates the original wave. The more samples you have, the smaller the steps are and the closer you'll be to the original. The disadvantage of higher sampling rates is the much higher volume of numbers you need to store. You might be familiar with the files that store sound waves this way this way. They are called .WAV files, and they usually take up a lot of disc space on your devices. The devices that perform this conversion are called Analog to Digital converters. Now you want to take your stored wave and play it back on your speakers. You need to take this wave approximation, that is basically what voltage the speaker needs to see at a specific point in time to produce the wave, and convert into the actual voltage the speakers need to work. This is done by a digital to analog converter. In a typical digital music storage system, there's usually an intermediate format, whare the wave is stored in a more compressed format, that introduces some loss of the original wave, with the benefit being that the file takes up less space on disc. This would be an MP3 file or similar. Now with streaming media what's more important is how long that file takes to download to your device. No streaming service will give you WAV files directly, or even the more modern FLAC format which typically requires less space but doesn't lose any of the wave. Your getting an AIFF, an MP3 or an OGG. The specifics of this are not so important, but the reality is that by converting from a WAV or FLAC some of the original wave is lost. This happens if you use a streaming service, or if you are dinosaur that still does MP3 files. Let's break down where some of the perceived issues occur in this set of transactions that make up a digital music system. There is both loss of original fidelity and noise in recording the sound picked up by the microphone when it is stored. When it it becomes compressed so that it can actually be used, either for streaming or stored on a device for playback, you lose yet more of the original wave. When you playback the file, there will be noise and sometimes further loss induced by the DAC. So, If you been following along, you might be thinking, Analog is surely best then, less steps, closer to the original wave\" this is not always true. All Analog systems are susceptible to noise. This can have a serious impact on how good both the recording and the reproduction sound. Many billions have been spent trying too eliminate noise from these systems. It continues, as you must still have a microphone and a speaker to record and reproduce sound. (I'll use reproduce, as you can to some extent eliminate the mic with modern music production where a great deal of the sounds you hear might be generated digitally.) Digital systems don't have an issue with noise. And the \"loss\" of fidelity induced by compression doesn't really have an impact on how you experience the sound. All sound waves have elements that the ear can't actually hear, but when you record the wave, it is stored anyway. Formats like MP3 and ogg are extremely good at getting rid of the bits of the wave that your ear wouldn't be able to hear, even the system reproduced it effectively. There is also the advantage of digital signal processing, which is a process of eliminating noise, and dinner times effects that make the sound better using software. It's only possible to do this in a digital system. It's cheaper and more effective than what is possible in Analog systems. It's also worth considering transmission of an audio signal, A digital signal, whether it's DAB radio transmission, Bluetooth or the HDMI signal from your games console won't get noise induced into it. It'll work, or it won't. It won't be better some days than others or deafen you cos you put your phone too close to it, or because you've got a bad connection or anything else. You don't have to eliminate noise to repeat it between multiple locations. It can even self heal if something does go wrong during transmission using a technique known as error correction. Because the difference isn't really important. Both are a part of a system. What you hear is \"Analog\". You can't avoid that. These days it's almost impossible to consume audio without some kind of digital technology, somewhere in the process, and that's overall a good thing that has made the experience better, not worse."
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m0ejle | How do we store memories? | I searched in the net and what I got are different parts of brain functioning for this. And I saw something like goes in then opposite but I don't understand any of it. | Biology | explainlikeimfive | {
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"Neuroscience PhD here. We haven't got a fucking clue. We have some very general ideas about what kinds of mechanisms it might involve (it might have something to do with changing the strengths of connections between brain cells), but that's like saying hard drives work by changing the magnetization of bits of metal.. sure, that may be the operational principle, but I still don't know how a whole entire hard drive WORKS. And the brain is nauseatingly complex, compared to a hard drive.",
"We do not know. What we see is that there are some areas of the brain that have a higher chance of causing memory loss or other memory related issues then others. So we do have some vauge idea of some of the areas that might be critical for storing and recalling memory. But we do not actually know how the system works. That does also indicate that it is a very complex system.",
"* Your memories are not like computer files they are more like a series of \"clues\": your five senses and emotions factor into memories * A theory about sleep and dreams is that (among other things) it's memory consolidation. Your brain organizes memories while you sleep - one correlation is that people who learn new things in a classroom or formal training report lots of dreams when they sleep. * Some memories fade or become disjointed because they are not used. That person from your teen years that interacted with -a lot - is now \"the dude with the shirt\" because the memories weren't used, or weren't used that much. * You can recover some of that, so when the \"the dude with the shirt\" send you a FB request, your brain will try to get as much as it can - but will fill in the blanks with new information. The key takeaway is that memory isn't like a DVD or a photograph - it's a living thing that can be replenished or \"die\" based on how it's used."
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m0et31 | If a person passes away, leaving their assets or money to their pets within their will, what actually happens to the money or assets? What happens to the pets? | Other | explainlikeimfive | {
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"Well pets don't get to own assets so really needs to be in a trust managed by nominated person(s) who will use the money to take care of the pets.",
"And just so you know, there is a legal concept called \"Fiduciary Responsibility\" which basically means a person/company/trust is *legally* required to make the best decisions in the interests of the party they are responsible too. So if I leave $500k to Boopsie, and the person handling Boopsie's trust decides that Boopsie needs a new sports car, that's actually a crime. That's what helps ensure stuff like this goes as intended.",
"Before death, the person sets up a trust to care for Boopsie. The trustee is paid $X to manage the trust and care for Boopsie. The trust specifies where any remaining money goes on Boopsie's death. The will gives all assets to the trust. On the person's death, all the assets go to the trust.",
"Is this because you saw the post that said a deceased Tennesseean put $5mil in their trust for their pet dog because she was a good girl?",
"That is something which needs to be stated in the will. Normally you would state a trustee that would actually manage the money and take care of the pet. Often with detailed instructions for how to spend the money on the pet and what to do if the pet dies.",
"So basically, if I have understood this properly, you can leave your money to a pet but, in the will, you have to nominate an actual person to take care of the pet using the money you donate, and also a place for the money to go once the pet dies. Is that correct?",
"They normally designate a human or an organisation to execute the will on behalf of the pet, so humans decide how to spend the pets money on behalf of the pet and for the benefit of the pet.",
"Just wanted to elaborate a bit (based on an NPR story I heard a while back), because there are (at least) two different ways to establish a trust for one's pets, each with their pros and cons. The first is as has already been mentioned; a trustee is chosen to take care of the pets using funds from the trust, and then is granted the remainder of the trust on the pet's death. Now obviously, the creates a perverse incentive for the trustee to 'hasten' the pet's death, so that they get paid quicker and get more return. So often there with be a third party (sometimes a lawyer) whose job it is verify that the trustee is acting in good faith, and that no foul play is involved with Boopsie passes. Another way, however, is to give the trustee a generous regular stipend as long as the pet lives, with the remainder after death going somewhere that the trustee doesn't benefit (perhaps family, or a charity). Now the trustee has a strong incentive to give Boopsie the best care possible. But they *also* have an incentive to hide Boopsie's eventual demise, perhaps by finding a new pet that looks enough like Boopsie to fool the lawyers involved. So said lawyers will have to watch out for this kind of fraud as well.",
"The pet gets to go and “live on a farm” somewhere distant and pretty, and the trust holder lights cigars with $100 bills.",
"1. No lawyer would ever let you do that. At best, you could establish a trust that is tied to caring for the animals upon your death. 2. If you somehow managed to do it anyway, you functionally would have died intestate, i.e., without a will, so state law would decide who gets your stuff, including your pets.",
"Pets themselves are personal property and cannot be given assets, however, someone can be called a Trustee to hold the funds for the pet’s personal care and when the pet dies the assets would be put back into the estate to be divided accordingly. It probably varies from country to country. You may be referring to the front page Reddit story of the man who gave 5m to his dog when he died. Crazy stuff!",
"if you choose to do this, it's very important to have all the fiduciary documentation set up correctly with an actual lawyer. many people have died without the proper pet probate planning, a situation known in legal circles as a Boopsie Oopsie."
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m0ewv6 | What are NFTs in the art world and why/how are they bad? | Other | explainlikeimfive | {
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"NFTs are non-fungible-tokens. They work pretty much like bitcoins only that they are unique and tied to an individual piece of art. So only one person can own this piece of art at a time. The enviroment suffers because to keep this system up a lot of computers need to run at full power to prevent people from cheating the system (who is right is decided by a repeated computation race, to cheat you'd need to win this reliably). So just keeping the system from collapsing takes a LOT of electrical power. I don't know why it's bad for the artist, but someone will propably chime in with that info."
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m0f04g | How does reCAPTCHA know I'm human just because I ticked a box? | Technology | explainlikeimfive | {
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"It actually record the movement before ticking the box. If your movement are too \"robotic\" (pure straight lines, instant teleportation of cursor, miliseconds reflexes) the recaptcha consider you might be a bot.",
"Robots generally either teleport the pointer or move in straight lines. Humans have tons of tiny vibrations in their movement. If you try to use the captcha on mobile you are much more likely to be asked to tap images.",
"the short version is : it doesn't. the long version is that the tick box isn't \"i'm human\" it's \"allow this web-page to check my cookies\". if your browser has tracking cookies on it, then you've been doing \"human things\", and browsing the web like a good consumer, so there's no verification. if your web-browser has no tracking cookies on it, or has 3rd party cookies disabled, or you just loaded straight into the page with the reCAPTCHA on it, you'll get the stupid \"click the boxes with fire hydrants in it test\"."
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m0fwvc | How do USB Flash Drives store information? | Technology | explainlikeimfive | {
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"Each bit is stored in a MOSFET transistor. A transistor have three terminals. A source and drain for the current and a gate which controls if the transistor will allow current through or block the current. So be charging or discharging the gate we can controll if a signal is allowed to pass through the transistor. But in flash memory we do not want to accidentally have the charge leak out of the gate as we can not constantly be charging up the gate when you unplug it. So we make sure the gate is isoletad from all electrical connections. This does however pose the problem of how you can charge and discharge it to set its value. The solution is literally quantum physics. By manipulating the charges in the transistor and in an additional gate on the transistor using very high voltage you are able to quantum tunnel electrons through the insulating material to charge or discharge the gate."
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m0ga11 | Why in many molluscs/gastropods, the shell always forms in a clockwise spiral as opposed to a counter-clockwise spiral. | Biology | explainlikeimfive | {
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"Apparently [there's a gene responsible for that]( URL_0 ). Don't know why clockwise is the default, though."
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m0gdwh | why are dolphins and other sea mammals able to deal with seawater whereas any seamen would rather die of thirst than drinking only one cup of saltwater | What is there essential difference? Is there some kind of filter and if so, where and how does it work? And what about other fish? Do they employ the same mechanism? And seaweed and stuff? My basic understanding of living cells says that much salt does much harm, therefore as far as I’m concerned, there should be no living cell in the whole wide ocean. Also interesting: how do eg salmons perform the transition between sweetwater river courses and their long mating routes across the ocean? | Biology | explainlikeimfive | {
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"There is not much research on this so good question Their kidneys are super cleaners compared to ours. Also scientists say they get their water from the food they eat.... this is debatable as many whales migrate long distances and food is not always readily available.",
"Although it’s literally all water, many of the animals in the ocean treat it a lot more like a desert. The water is too salty to ingest in large quantities, and it’s constantly trying to dehydrate your tissues through osmotic pressure. The struggle in that environment isn’t really that different from a desert animal. So like a desert animal, fish and oceangoing mammals must conserve their body moisture and source new water from their diet instead of from the environment. They expel most of the saltwater they ingest when eating, and have very powerful kidneys to deal with the rest."
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m0gem7 | Why do our legs shake if we lift our heels whilst sitting down? | Biology | explainlikeimfive | {
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"I had the same issue with sitting up in bed. My whole body would shake before I was in a resting position. I was anorexic at the time. The reason they shake is that you're weak in those muscles. Train them and you won't have this issue.",
"I know what you mean. It's an involuntary 'quiver'. I would guess that it's because the central nervous system isn't used to controlling the muscles that keep the muscles and feet still when they don't have the ground underneath them, or that the muscles themselves aren't used to it. But I might be way off, so wait for someone who knows the real reason to jump in and correct me :D",
"I'll quote what someone quoted a year ago of what someone said 7 years ago. But if you want to look it up, it's called the Golgi Tendon Reflex. URL_0 \"Physiotherapist here, OP need not worry... ...it is a reflex response,... ...It's part of the Golgi tendon reflex. Golgi tendons are small receptors located in every muscle that protect them from over stretching damage. They do this by recognising when a muscle is over stretched and then sending a message to your spinal cord- which then sends a message back telling the muscle to contract to prevent it hurting itself. When OP goes up onto his tiptoes the Golgi tendons sense his calf (gastrocnemius, soleus and to a lesser degree plantar is) is stretching, so the it sends the message to the spinal cord and we get the contraction reflex. So then his leg rises due to plantar flexion at the ankle and the calf muscles relax. After they relax, his leg drops again- we get the stretch- then the stretch reflex and the cycle repeats, carrying on the continual bounce of his leg... ...Hope this makes sense! TL; DR Golgi tendons.\""
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m0gzen | How do touchscreens work? | Technology | explainlikeimfive | {
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"Touch screens are essentially a large surface of open electrical circuits. Your finger is electrically conductive so when it presses a part of a screen it completes a tiny circuit and the device registers this as a \"touch\" at that point. In order to register a touch you need a slightly electrically conductive touch-er. This is why any old glove will not register as a touch but gloves with a special \"touch screen\" material will work."
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m0i0yd | How does resolution upscaling and remastering works in retro video games and movies? | Technology | explainlikeimfive | {
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"Imagine you have 5 dots on a piece of paper, in a line. You could take a pencil and draw that line through the 5 dots. Now, looking at your line, you could draw lots more dots on the same line - maybe 50 or 100! A computer can use math to look at an existing picture/shape/whatever and basically compute where to add new dots (ie upscale resolution) - the same as you did with your line and pencil.",
"For video games that are 3D there's nothing that needs to be done, it just accepts whatever resolution it's given. This is because 3D elements are stored as a series of points with lines connecting them. A 1 inch long 3D line and a 1 mile long 3D line take the same amount of space to store because you only need the starting point and ending point to draw them. Since most games used to (and some still do) not make the user interface (UI) independent of the render resolution this can result in tiny and unusable UIs. The UI will shrink as the resolution increases unless the developers account for this, such as using a UI that uses relative sizes rather than absolute sizes. By this I mean a UI element might be set to take up 50x50 pixels no matter what the resolution of the game is. If instead they make the UI element take up a percentage of the screen then it will stay the same size as resolution increases. If the aspect ratio changes though this will still cause the UI element to warp. This can cause things that are supposed to be circles to become ovals, and in the case of 2D game stretch them out. For 2D games all of the elements are set to a specific size unless they use a vector format (this works the same as I described for 3D), but let's say they all use a specific size. In this case when you upscale the image there are algorithms that try to increase the size of the image while making it still look like the original image. None of these algorithms are perfect and you can only upscale a 2D image so far before the image starts getting messed up. For movies if it's film they go back to the original master and scan it in at a higher resolution. Film is a visual format that doesn't have a resolution, the image is stored physically on the medium. Sometimes when they shot on film they knew they were going to only show it on TV so they would frame shots for 4:3. This happened with Star Trek TNG. Just outside the 4:3 frame were the edges of the set, crew members, lights, or other things. Even though they could have made it widescreen they had to stay with 4:3. If it's video or digital they can't do this as there's nothing to scan in. The resulting video output is a specific resolution. Upscaling is still possible, but you can't get extra detail that doesn't exist...or can you? There's a new method called super resolution that uses the magic of AI to upscale the image. Unlike other upscaling methods super resolution can create detail out of nothing. DLSS is a real time implementation of super resolution, it uses multiple frames to intelligently create the output frame. There's many picture upscalers out there as well. It's also possible to do this with video but I've not seen any publicly usable implementations yet."
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m0i4wc | why do some stores put ice when mixing the dough in the machine? | Other | explainlikeimfive | {
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"Depends on what they are making. Some things, like flaky biscuits and things you want layered need the fats to say solid so that they form fat solids within the gluten that the flour creates. The gluten is the structure, the fat creates the crispiness and the flakiness. Adding ices keeps the fats solid."
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m0ij6h | Why can the brain not adapt to and ignore tinnitus much like one can with clothes, smells and other sounds? | In the case of loud noise exposure, the microscopic hairs are damaged. If our brains are so adaptive, why can't our brains adapt to the input being different? | Biology | explainlikeimfive | {
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"Because the brain is responsible for it. Tinnitus is caused by the brain not your hearing system, what I'm calling the ear and all the parts in it. Basically when you have hearing damage the brain is like \"Hmmm it's quiet ... TOO QUIET I'll make them think they are hearing a high pitched ringing noise. Problem solved\""
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m0jqb1 | What's the physiological difference between being unconscious, and just being asleep? | Biology | explainlikeimfive | {
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"Asleep = the restaurant is closed to customers but the staff can still be working inside to prep for opening. Unconscious = the restaurant is closed to customers and the normal staff went home so the cleaning team can do their work.",
"Being unconscious would generally mean your brain isn't working as it should, and is an absence of wakefulness generally caused by pathology (lack of oxygen, stroke, psychiatric) Fainting/coma would fall under this category. Sleep is regulated by our circadian rhythm driven by a specific portion in the hypothalamus. This portion (called the suprachiasmatic nucleus) affects our arousal state. The absence of wakefulness here is a controlled and metabolically distinct process and can be affected by environment (like light)"
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m0k9fh | Why do small objects grip to wet surfaces best, but large objects grip to wet surfaces worse than a dry surface? | My question probably doesn't even make sense so here is an example. If you pour water over a massive boulder and throw sand at it, the sand will stick to the rock better than it would without the water. For larger objects like your hand, it would make it much harder to climb that rock than without the water poured on it. Why is it the opposite? | Physics | explainlikeimfive | {
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"Water really likes to bond to itself. It forms lots of intermolecular connections between various water molecules. This makes it hard to separate water. Think of sticking two objects together with taffy. It adheres to both itself and the two objects and holds them in place. Water does the same thing, but to a lessor extent. Water can manage to \"hold on\" to a very small object like a grain of sand. However, something larger will greatly overpower these bonds and then it just acts as a lubricant, with water molecules sliding over each other as your hand moves across the rock."
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m0kvul | What’s with all the fire warnings on kids’ sleep clothes? Are they gonna roll themselves into starting a fire? *totally confused* | Physics | explainlikeimfive | {
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"In the '50s there were hundreds of lawsuits over some Halloween costumes catching fire. This led to the 1953 Flammable Fabrics Act.",
"The idea is that in a nighttime house fire, their clothing should be somewhat protective. Children's sleepwear must either be 1) flame-retardant or 2) close-fitted to the body (which means it won't have as much oxygen and won't catch fire as easily). For a similar reason, [mattresses are required to be fire-resistant for 30 minutes in open flame.]( URL_0 ) People should have a chance to get out of a house fire even if they're asleep when it starts.",
"There’s a fascinating episode of Articles of Interest (a pod mini-series from 99% Invisible) about this very subject. [ URL_0 ]( URL_0 )",
"Those types of clothing are fire/flame retardant and must self extinguish The regulations are published in the Code of Federal Regulations at 16 CFR Part 1615 for children’s sleepwear sized above 9 months and up to 6X, and at 16 CFR Part 1616 for children’s sleepwear sized 7 through 14. The two rules contain basically the same requirements, with the main difference being the sizes of the garments covered by each.",
"Interestingly some squashed research into SIDS (sudden infant death syndrome) iirc in Ireland showed that the off gassing of new baby items with all their fire retardant chemicals had a higher impact on causing infant death, especially in the face down position. This in part led to the “back to sleep” campaigns. While many of the original fire retardant jammies were self extinguishing, they were made of polyesters / synthetics that created another problem, the fabrics would melt into burn wounds compounding treatment. Now with decades of trial and error, it’s clear that well fitting all cotton pajamas are a safer bet. No chemicals to leach into the body/ environment or wear away with washing... In a fire they’ll rapidly burn away, but not cause engulfed burning and no bits get melded into wounds. Well fitting so trailing edges don’t catch from heating sources or god forbid passing flames while exiting a fire..."
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m0l32q | What does "adjusted for inflation" mean and how are they related to investment portfolios? | Other | explainlikeimfive | {
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"Inflation is the value of a dollar getting lower with time. You always hear people talk about the time gas was a quarter a gallon, or how you could buy a pack of gum for a nickle. Well, because of inflation, now it costs $3.25 a gallon and a dollar for a pack of gum. There are more people, more companies generating more money. More money = the value of money goes down. So when they adjust for inflation, it means they're showing you all the numbers based on how much the dollar costs *today*, so that you have a direct, easy-to-read comparison. For instance, say someone is saying \"this cost $50 in 1950 and $300 in 2021\". If it's *not* adjusted for inflation, then you might think that the value of the investment really went up quite a bit since 1950... But when you *do* account for inflation, you'll see that that 1950's $50 is actually worth $542.70 in 2021. So when you adjust for inflation, you see that investing in whatever that was in 1950 would have actually resulted in a *loss* of value, assuming you just bought $50 of whatever and never touched it again."
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m0l93a | Is electricity still affected by gravity? Like, does it travel slower when going up compared to going down? | Physics | explainlikeimfive | {
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"Electricity is the movement of electrons. Electrons are particles that have a mass, albeit a very tiny one. Earth's gravity would have an effect, but considering it's moving at a speed comparable to the speed of light, it's practically negligible. So, basic answer is yes, but it's such a small effect (at least on earth) it's practically no",
"They (electrons) have mass so they are affected by gravity. The speed of their movement is more determined by internal resistance. That said, it’s near the speed of light."
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m0mlb0 | What is a computer actually doing when it fully deletes a file, and why are some files too big to go into the trash so they have to be "deleted permanently?" | Technology | explainlikeimfive | {
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"When you \"fully delete\" a file, the computer doesn't automatically and instantly do anything - it just tells the hard drive \"hey you can write over that old data with new data if you need to\". That's why it's possible in some cases to recover \"deleted\" files, because... the file's still there until something else comes along and takes its place. As far as the files being too big, that's just an artificial limitation put on the Recycling Bin in Windows. They assume that if you delete a single Word document that you might need to easily recover that later, but if you are deleting a 500 MB installation file for something, you'll probably need that space *sooner* rather than later and you probably *don't* need that file again. You can actually adjust the recycle bin's limit to be bigger or smaller as you want. Making it bigger just means you won't have as much free space on your hard drive when you *recycle* files until you actually manually empty the recycle bin, though.",
"The files are basically moved to another temporary location (it says \"move to recycle bin\" vs \"delete permanently\"). The recycle bin is usually a temporary location inside the drive partition your OS is installed in, and if you're \"deleting\" a file in another location, a file larger than the available free space in your OS partition - it can't be moved to that drive.",
"The trashbin is just a folder that isn't really special except it remembers where the stuff came from before. So files in it aren't deleted at all yet. If you actually delete a file it's space in the memory is just declared empty. So the bits stay, but other programs can claim the space to save their own bits by then overwriting the old files for good"
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m0mol2 | Why do spacecraft with a small hull breach not decompress immediately | I remember seeing several instances where spacecraft (i.e. ISS) had small holes in them and they were fine (NASA even didn't wake astronauts once). Since the pressure difference is so great (space is a vacuum), how come there's no explosive decompression (all the air is sucked out at once)? | Physics | explainlikeimfive | {
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"> pressure difference is so great That's the thing - it's not. Atmospheric to vacuum is the same difference as sea level to 10 meters under water. It's just 1 bar, or 1 kg per square centimeter. For comparison, a municipal water system usually has a pressure of 3-5 bar, and a dripping tap also doesn't blow your house up.",
"The pressure different isn't that great. One atmosphere of pressure is around 15 psi. All things considered, that's not very high (your car tires are 2-3 times that, and don't blow up when poked). Then there's the fact that small holes really restrict the flow of liquids and gasses through them. Holes can be a problem for materials that tear easily, like how s balloon pops. Materials that are much stronger won't rip apart like that, and can tolerate small holes no problem. You can even test this by putting a piece of tape on a balloon and then poking through the tape with a needle. You'll just get a slow leak.",
"You are correct the pressure “difference” is great, but only in terms of ratio. In fact the ratio of pressures inside and out tends to infinity. But a phenomenon of fluid flows named “choking” puts a limit to how much of the air inside the craft can leave the hole per second, for a given size of hole. As the pressure ratio grows between inside and outside, gas indeed starts to leave faster and faster. However for a high enough pressure ratio (only about 2 for air!) the gas will reach the speed of sound and you get something called a choked throat. Because any gas leaving the hole then goes faster than sound, it actually has no way to tell the air still inside to leave faster- the expansion wave telling air it hits to go faster just flies away from the spacecraft! So, even though there is an almost infinite ratio in pressures inside and out, the mass flow is restricted by the usually small size of the hole. The hole doesn’t break open because the pressure difference (not ratio) is not enough to break the strong and rigid material. Spacecraft aren’t balloons!"
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m0mq9b | How come we’ve never cloned dinosaurs? | Did we learn our mistake from the jurassic park series? | Biology | explainlikeimfive | {
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"DNA breaks down really fast. It'll depend a lot on the environment, but roughly half the DNA breaks down after around 500 years. You can imagine then, that after millions (or hundreds of millions) of years, there'd be no useful DNA left to clone.",
"So, Jurassic Park is based on the idea that we could get Dino DNA from mosquitos trapped in amber, and use that to make clones. In reality, even if a mosquito bit a dinosaur and then got immediately trapped in amber, the DNA would still degrade and not be usable millions of years later. It's not possible with our technology to be able to do that.",
"We don’t have dinosaur DNA. You also still need a surrogate mother of the same or a very closely related species to make a clone in real life; there’s no living animal today that could work for that.",
"Since we can't clone dinosaurs for the reasons everyone has listed here, what we CAN do is reverse engineer them through gene editing. It's exploratory science that we've not quite nailed down yet, but we've done some experiments to 'de-evolve' animals- specifically chickens to get them to somewhat resemble their dinosaur parentage. 2 legged dinosaurs were basically chicken with teeth. We're working on it.",
"Even ignoring the ethical and safety questions around a dinosaur-based theme park, the ability to clone dinosaurs just doesn't exist and likely won't, as far as we can tell. DNA breaks down over time, and even if it were preserved in amber (like in Jurassic Park), the soft tissues and DNA present in the sample will have degraded millions of years ago, leaving only a husk preserved in the amber. Under normal conditions, DNA completely breaks down over a few thousand years, let alone a scale of tens of millions. That's not to say that we *couldn't* find some unbelievably well-preserved dinosaur DNA in the future, but it seems very unlikely that it's possible. We've found some examples of extinct DNA in really specific conditions - like buried in permafrost, maintained at very low temperatures without ever warming up - but even then, the oldest I believe we've found is around a million years old. We'd need to find something 65x as old and perfectly preserved in order to even think about the possibility of dinosaur cloning.",
"DNA, the instructions for how to make a living thing, are needed to clone an animal. We only have fossils of dinosaurs, which don't contain any DNA. The idea of getting that DNA from an insect in amber is pretty unrealistic, it doesn't last very well even sealed away in amber. Also, if you clone something you need another animal to carry that embryo. We cloned a sheep because we had another sheep to put it in. We can't yet clone Wooly Mammoth, despite possibly getting an Elephant to birth it. The DNA just isn't viable despite being frozen and despite only being tens of thousands rather than tens of millions of years old."
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m0murq | How can light be a particle and wave, or have both properties? | Physics | explainlikeimfive | {
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"Look at this from the opposite direction, coming from the observation and going towards the model, instead of coming from the model side. You see a certain set of things. Some of them make you think \"well, that's just like a bowling ball behaves, so it should be a particle!\". But then there are also some that make you think \"well, that's just like ripples on water behave, so it must be a wave!\". Particle and wave are in the end just attempts to cast the properties of light into a more graspable model. And the best we came up so far is a mixture of a particle and a wave."
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m0n36c | What is the butterfly effect? | Mathematics | explainlikeimfive | {
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"It's an idea that an action can have major unintended consequences. In the 1960s, a meteorologist Edward Lorenz was experimenting with predicting the weather with computers, and found that something as small as a butterfly flapping its wings one way or another could dramatically alter weather patterns, because that small flap of the wings would shift air a little, and that little shift could be enough to change something on the large scale. It's been used a lot in time travel stories, with the idea that if you go back in time and make a tiny change, like stepping on a twig, the chain reaction that comes from that could change the future in a huge way. So like, a time traveler could step on a twig, and then an animal that would have eaten that twig starves, and then another animal can't eat it, and the chain reaction occurs that results in a world where humans never existed.",
"A small change acts to change things much larger than it; drop a rock on a gravel slope and it causes a massive landslide.",
"The butterfly effect is the thought that if a butterfly flaps its wings in Texas there is a tornado in Illinois. Just that a small ripple somewhere can turn into something much grander somewhere else. Imagine the domino meme. Tap a small domino and it’ll eventually hit enough things where it can knock over the huge one.",
"A butterfly flaps its wings on the African plains. This disrupts a small amount of pollen from a nearby plant, that lands on a lion's nose making it sneeze. The large herd of wildebeest nearby hear the predators sneeze and become alarmed, causing a stampede. The stampede creates a ton of dust to rise into the air. That dust cloud floats over the Atlantic and water clouds form on it. Those clouds dump torrential rain on the American east coast and collide with a front coming from the west coast creating tornadoes in Arkansas."
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m0nd8z | What happens with periods in space? Because of like no gravity (I might just be stupid) | Other | explainlikeimfive | {
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"Not much different from earth. The period is moved out of the body but muscular contractions so gravity doesn't have much effect.",
"Swear I just had this convo the other day with my hubby. He said they chase down floating blood bubbles with maxi pads lol",
"Gravity alone isn’t responding for menstrual flow, contraction of the uterus expel the shed endometrial lining. URL_0",
"When there is a female astronaut they is pads on the station in case. But what they do is take a pill daily starting a week before launch that stops you from getting your period",
"Ooooh good question! And yes of course the muscles in the uterus are what she’s the lining to create the period but, that still doesn’t answer how the fluid is collected and removed from the canal and vaginal area. It’s just as good a question as wondering what astronauts do in order to poop or pee ... it’s just that it’s less often considered by those of us not going to space. (Well, or so it seems by both this thread and the fact that I am a woman, doula, birthing educator who coincidentally loves all things science/space/sci-fi and I never once even considered this.—Which kinda seems so very obvious not that the OP brought it up!)"
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m0oznv | why can animals gets all the needed nutrients and vitamins from a single source of food like meat or grass, but humans need a balanced diet? | Biology | explainlikeimfive | {
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"Because animals don’t just eat one thing. “Meat” and “grass” are just generalizations. For example, grazing animals like deer or horses or cows or goats that eat “grass” are probably grazing on and eating a dozen different plants during that day, and eating everything from the flowers, to the seeds, to the leaves, stems, roots. Sure they eat “grass” but that “grass” is actually a wide variety of things. The same goes for carnivores that just each “meat”. Sure they’re just eating “meat”. But that meat includes muscles, kidneys, liver, heart, lungs, stomach, intestines, bone marrow, brains, eyes, skin, cartilage. That’s is a wide variety of items that all have their own variety of nutrients in them.",
"Because animals don’t object to letting large numbers of their population die off until they adapt to only needing the nutrients provided by the food that is available in their environment.",
"The short answer is evolution - all animals’ diets are the result of millions of years of evolution. Herbivores evolved to live on a diet of plants. Carnivores evolved to live on a diet of meat. Humans are omnivores and evolved to survive on a diverse diet - but that means we have to keep eating that diverse diet",
"Different animals have developed the ability to produce different types of vitamins and amino acids depending on their primary diet. With the optimal being the ability to make just the right amount of nutrients that you do not get in your diet as this does not waste any extra energy. Humans have evolved mostly on a diet of fruits, vegetables and insects with some animals from time to time. That is a pretty varied diet which means that compared to a lot of other animals we do not spend a lot of energy making nutrients when we can get everything from our diet. We are able to make some though but not as much as animals which have evolved on a very monotone diet. That being said it is possible to live on very monotone diets as well, even some pure animal diets. There are plenty of tribes we know of which have specialized on very specific plants or animals. However it is very hard to develop such a diet and requires a lot of trial and error to find the right way to prepare the meals and the right ingredients. When we have tried to develop such a diet to simplify food supply for example on sail boats we have usually failed. So the safe option is to make sure you eat one of everything available to you.",
"There’s an important difference between humans Ruminants (cows, sheep, deer, etc). They multiple stomach chambers, and multi-step digestive system. So when a cow eats grass, it swallows it without chewing much. It eats a BUNCH of grass, its first stomach chamber called the rumen is about the size of 55-gallon trash can. Then it will lie down and digest. While relaxing, it will “chew the cud” meaning it forces grass back into its mouth so it can chew it more, over and over. This allows the grass to be broken down much further. They also have specialized bacteria in their gut, that humans lack, to extract as many nutrients from the grass paste as possible. When a human eats grass, it mostly just passes through us undigested."
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m0qu4d | Interpolation in songs? | Specifically in regards to being done to avoid licensing samples. Context for the question. Ava Max has a song called My Head My Heart i heard on the radio and immediately recogocnized as ATCs Around The World.. i didnt think anyone would straight up rip off a songs entire music? Is it not illegal? Is it just cheaper than sampling? Yell me what you know! | Other | explainlikeimfive | {
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"It comes down to ownership of the song vs. ownership of the recording. If I wrote song \"XYZ\", that song belongs to me. But when I record \"XYZ\" in the studio, that specific *recording* might be owned by the record company, the musicians who played the music might also have ownership shares. So you wanted to put a snippet of \"XYZ\" into your song as a sample, you'd need to get permission from, and pay money to, the recording company for their recording, the musicians for their music, and me (the songwriter) for my song. OR you could record a new version of the song yourself and only have to pay me, the songwriter, for the song. This is why owning the rights to music are such big deals. Two anecdotes are apparently the Beatles telling Michael Jackson the real money in music is owning the recordings, not the song rights. Michael Jackson then promptly purchased the Beatles recording rights from the record company and made a killing. John Fogerty had a similar issue when he made solo music after quitting CCR, the record company came back and sued him because his solo music sounded *so much like CRR it was copyright infringement on their records of music he wrote and recorded!* (he ultimately won that court battle)"
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m0qvlo | Film is rearranged metal particles on tape which are read by an electromagnet. CDs are discs with burned pits in them which are read by a laser. What makes one analog and one digital? | Technology | explainlikeimfive | {
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"CDs pits represent binary data, on or off. Film's particles (or grain) can be any color, making it analog. A good way to determine if something is analog vs digital is how the smallest unit of measurement can be measured. If it can only be on or off then it's digital, but if it can be on, off, or some value in between then it's analog.",
"Film? Do you mean audio cassette? In any case, the audio cassette if that's what you mean, represents a smoothly varying signal, which corresponds to the magnetic field on the tape. WHen recorded, the audio signal is directly fed into a magnetic head, and that head (which is just a coil of wire) creates a changing magnetic field, which magnetises the tape in a way which directly represents the analog audio signal. There's no converting happening, except between electrical and magnetic. With a CD, what's encoded in the pits and lands is digital data, which has to be fed into an digital to analog converter to turn it back into the sort of signal that can be fed out of a speaker.",
"Digital just means there's an extra step in the middle to translate everything into 0s and 1s. Film uses the physical properties of the metal and clever manipulation of chemistry to store an image. CDs uses a laser and the physical properties of light to store an image, but the image was first translated into 0s and 1s (which correspond to the lands and pits on the disc) Edit: More examples after I saw you meant audio. With a magnetic tape, the soundwaves that were recorded get directly transformed into magnetic fields of varying strength. The tape essentially store \"magnetic waves\" that are a 1 to 1 transformation of the original sound waves. With a cd, those sound waves are first translated into 0s and 1s before being transformed into lands and pits. With out a computer that knows the code, those 0s and 1s are meaningless.",
"CDs are digital because the data is stored in a discrete fashion: binary, 1 or 0. Film is stored in an analog fashion because the data is recorded as a gradient (of brightness, color, etc), so it isn’t discrete."
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m0r8vq | Why does glue/adhesive not harden inside its packaging | We use adhesives when we want to stick to surfaces to one another. The end by-product is the adhesive hardening. However, when adhesive is stored inside its pack, why doesn't it harden within the pack and never come out? What makes it remain liquidic inside its packaging even after a long time? | Chemistry | explainlikeimfive | {
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"Many adhesives contain a solvent, a liquid that can dissolve them. As long as the solvent is around, the adhesive stays soft. The adhesive \"dries\" when the solvent evaporates and the adhesive is left behind. So as long as the container is closed the solvent can't evaporate. For simple white glue, the solvent is water. For rubber cement or plastic glue, it's some kind of organic solvent. Other adhesives contain precursor molecules that undergo a chemical reaction when they're exposed to a catalyst (a chemical that triggers the reaction). That can be water (which is almost everything in tiny quantities), oxygen, a dedicated hardener (e.g. epoxy resin), certain metals (Loctite), etc. In thoses cases, as long as you keep them away from the catalyst then you don't trigger the reaction."
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m0r9qt | My bicycle light warns of radiation if you stare directly at the light. Why isn’t simply touching or being next to it an issue? | Physics | explainlikeimfive | {
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"This might be a bad translation or bad wording. It's extremely unlikely that a bicycle light would emit harmful (ionizing) radiation other than light. Light is technically radiation, so that's where the translation error may come in. Chances are they're just telling you not to look directly at a bright light source.",
"The definition of radiation is energy emitted as electromagnetic waves or moving subatomic particles. Many people imagine nuclear radiation when they hear “radiation”, but that isn’t the only kind. For example, light is radiation. Your bike light is warning you that staring into a bright light can hurt your eyes."
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m0seam | Laundry. How do you wash whites? Some of my white clothes have black logos/patterns on them - should I wash these with colors? | Other | explainlikeimfive | {
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"In my experience logos and prints don’t tend to bleed and stain everything else, but if you want those items to stay as like-new as possible you should probably wash them separately in cold water with a delicate detergent like Woolite. Washing them with colors will dull them, but washing them with whites will degrade them.",
"I personally wash all my clothes together in cold water...less likely to shrink or fade clothes, less likely to cause colors to bleed, etc. If I'm really worried about colors bleeding I'll was them in warm water a few times first, then wash them with cold the rest of the times. Predominantly white/light clothes don't really have this problem though...so you can just wash them together with the rest of your clothes."
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m0th9d | how do popping joints work | Biology | explainlikeimfive | {
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"Non-eli5: cavitations in synovial fluid eli5: you have liquid in your joints. That liquid sometimes get bubbles. When it does, and you bend your joints a lot, then those bubbles can collapse and make a noise"
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m0uii1 | How did Japan recover so quickly from WW2? | Other | explainlikeimfive | {
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"America pumping millions into the economy like with Marshalls Plan in Europe. Needed an ally in the Pacific region",
"America gave Japan and Europe boatloads of money to rebuild their infrastructure post-war in what was known as the 'Marshall Plan'. Under this plan they also became close trading partners with the US, and had to create democratic governments. Democracy + free flowing trade, so the theory goes, = stability and peace"
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m0v5nb | Why does sweet cancel sweet | Why is that when I have tea, coffee or hot chocolate and also eat something sweet like a chocolate or donut, just after taking a bite I'll sip my beverage and it will be bitter as hell. Why do taste buds do such a thing? | Biology | explainlikeimfive | {
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"Something like a donut or chocolate is so sweet, that it overwhelms the taste receptors for sweet, causing your brain to \"dial down\" their sensitivity, making the beverage taste much less sweet in comparison. It's like looking into a bright light for a second and being blinded for a little while afterwards.",
"It's a thing called habituation. basically, nerves are at their most sensitive when they aren't really being used. So, when you start eating something sweet, your taste buds for sweetness begin to lose their sensitivity. Meanwhile, your taste buds for bitterness are still as sensitive as ever. So, if you then taste something that's less sweet and more bitter, you won't taste the sweetness as much, but you'll taste the bitterness just fine."
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m0vpu2 | Why is the area on the sides of our stomachs, below are ribs but above our waist sensitive | Serious, I hate being touched their it hurts and I know others are the same, just unsure on the reason why that one area is sensitive | Biology | explainlikeimfive | {
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"There's lots of important stuff tucked away behind the skin in that area - kidneys, intestines, etc. It's protected by little more than some skin and muscle, so having an aversion to being touched there is a pretty good way to ensure that we instinctively protect that area when facing danger."
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m0wdc7 | when skinning an animal what happens to the butthole? Is there a hole where the butt was? | Biology | explainlikeimfive | {
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"Generally you'll disembowel an animal before skinning. The skin and large intestine will be cut and trimmed around the anus. Most skins and furs are then cut into more regular panels and shapes before use. There is a hole / gap at the top of the rear legs.",
"It kinda depends on how it's done. In skinning without gutting, there's still a butthole, the skinner cuts the skin around it so that the anus and intestines separate. With gutting, the anus is removed with the colon and intestines, and the carcass is ready to be cut in half."
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m0wicd | Why are there sudden changes of temperature when you’re walking near a running body of water? | Earth Science | explainlikeimfive | {
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"Evaporation takes away heat energy from the surroundings. So the water is sucking up energy, causing the surrounding temperature to fall. In a still body of water, the warm water rises to the top. This layer of warm water doesn't absorb that much heat before it evaporates. In a moving body of water, this layer gets mixed up, bringing cooler water up to the top, which can absorb more heat to evaporate. This is why the area near a moving body of water feels cooler than a still body of water.",
"Running bodies of water tend to disturb water from its liquid form into little water vapors. When water turns into vapor, it cools the air around it. This is called evaporative cooling. Evaporative cooling is the reason you feel cooler when you sweat. So how does this work? Sweat is made of water --two hydrogen atoms and one oxygen atom. Water molecules are good friends, and they like to hang onto one another. They do so when the hydrogen atom of one water molecule hangs onto the oxygen atom of another. When enough of these friends hang out together, you have liquid water. When large bodies of liquid water are disturbed or heated by the surrounding air, the water molecules get so excited they can no longer hang onto their pals. The more energetic ones break free from the bigger group, grabbing the ones with similar amounts of energy with them. This repeats, and they form smaller and smaller groups of water. When the groups are small enough, they escape into the air and turn into water vapor. This is where the magic happens. See, whenever the energetic guys break from their friends, they leave the less energetic friends behind. When enough high energy guys leave, the larger group to becomes less and less energetic, making them more and more chill. Same thing happens in the air, as this process repeats with the water vapor that already exists in the air. This makes the air more and more chill. Now with evaporative cooling causing air to be chiller, the wilder air tends to push and shove its way into the chiller air, which is what causes air movement (wind). All these things combine to make the sea breeze, and SUPER chill times on the beach with a Corona. Kind of makes me yearn for a vaction now when instead, I'm stuck at home explaining evaporative cooling on the internet. Man I can't wait for COVID to be over... Anyways, I digress."
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m0wyoq | How does genetic memory work? | How does a baby bird know to act like a poisonous worm when a predator shows up? The answer is genetic memory, but how does it work? How does it get encoded into dna, passed down, and executed. | Biology | explainlikeimfive | {
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"It might help to look at what our own instincts \"feel\" like. For example, how do you know to eat food and not to eat mud? It's probably a universal thing for people to try eating dirt, mud, etc. as a child, but outside of a few cases, this is something you do not make a habit of. Things like the flavour tell us mud is bad. Why is it bad? Because it tastes bad. Why is food good? Because it tastes good (at least most of it, some can be hit or miss). But flavour isn't an inherent quality of materials. It's purely in our minds, caused by taste receptors on our tongue reacting to certain molecules. The tastes considered \"good\" are tied to the presence of certain molecules, and vice versa for bad. The end result is that we \"know\" to eat food without specifically having to be taught. This connects to genes because the instructions for how to make taste receptors are encoded in DNA. Variations in the exact shape result in different preferences, such as the same food tasting pretty good to one person, but terribly bitter to another. > How does it get encoded into dna, passed down, and executed. You're thinking of it backwards. Things didn't start \"outside\" the DNA and then get encoded into it. Things start as DNA and then the DNA makes us, who do things. As for how DNA is passed down and used, there's a wide variety of educational videos and articles meant to teach this topic. [Crash Course youtube series]( URL_0 ) and [Khan Academy article]( URL_1 ). If you have further questions, do not hesitate to ask!",
"There's no memory, you have the cart before the horse. Let's say you've got a gene which makes your neck twitch, and you're therefore constantly instinctively and involuntarily looking in different directions as a result. That behavior causes you to spot a predator before you're killed, and therefore you survive to spawn offspring and pass on that trait. Genes don't learn, they only change at random, and the random ones changes which benefit the organism will help that organism outlast random changes which do not.",
"It might be more accurate to say the baby birds have instinct, rather than genetic memory. Memory implies learned behavior, while instinct is behavior that stems from evolution. At some point in time a baby bird had a genetic quirk that cased it to act somewhat similar to a poison worm. Predators found this off putting (either though learned behavior from a previous encounter with a real poison worm, or instinct of their own). Those baby bird lived to grow up to be adult birds, who had quirky children of their own. Over time that behavior became refined like only acting wormy when predators are around, acting extra wormy, etc."
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m0xrrm | why do animals (besides maybe some primates?) have “exposed” buttholes, while humans have “hidden buttholes” (between our cheeks)? | Biology | explainlikeimfive | {
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"> The way we sit normally? It's actually the way we walk. Specifically, as humans evolved to walk upright, our pelvis and the muscles that make up the butt changed from our nearest ancestors. This change was necessary to facilitate our evolved form of locomotion, which isn't seen in any other mammal. Rather, our buttcheeks evolved to support our upright walking, which ultimately hide our anus compared to other mammals.",
"Since we walk upright, we've evolved muscles around our butts, which accidentally hide our precious buttholes",
"You have it backwards. The \"hidden butthole\" is a tolerated side-effect of something that *is* advantageous, not something with its own advantages. We have large butt-cheeks because walking on two legs requires big gluteal muscles in that location. It makes using the restroom harder and less sanitary (animals usually don't need to wipe). But the tradeoff is worth it for the advantages of walking upright, so evolution had no \"reason\" to change it further.",
"Ever seen a gorilla walk upright? Find his/her anus",
"I assume you guys know there's a whole species named Cryptoprocta ferox, whose genus name means \"hidden butthole.\" I mean, like, there's a flap, so it's even more hidden than the human butthole. Depending on how hard you're looking.",
"There's a recent ologies podcast episode about butts that answered that and many more questions. I really enjoyed it.",
"Came here just to see the word 'buttcheeks' in an educational and insightful context. Not disappointed!",
"I've had a pet snake. I've had pet turtles. Lizards. Dogs. Literally all hidden. Even elephants that have big booty holes... They're hidden at least partially by the tail. The only exposed butthole is someone searching for one",
"That's very simple. We have a butt. Most animals do not. Why do we have a butt? Because walking upright needs your butt muscles to be stronger.",
"Oh! You need to listen to the podcast Ologies! Specifically The episode Gluteology (BUTTS) with Natalia Reagan! She’s an expert on butts and talks about this!",
"How many of you knew the answer from vsauce?"
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m0xvol | When the sun shines intensely onto greenery and buildings, they look especially crisp & hi-def. Is there a phenomenon going on here? | I have always noticed this, but looking through what I'm convinced is an orange-tinted bus window, the scenery looks even more unreal, as if a 4k ad you'd see on a TV. | Physics | explainlikeimfive | {
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"Your eye can adapt to a huge range of brightness levels. This is how you can see both under moonlight and in daylight even though the latter is literally thousands and thousands of times brighter than the former. One of the ways it does that is by contracting your pupil to a smaller hole to let less light in. A side effect of that is this focuses the incoming image with greater sharpness. In particular, the [circle of confusion]( URL_0 ) gets smaller and the [depth of field]( URL_1 ) gets larger. The latter means that most of what you are looking at is simultaneously in focus, which is, I think, a big part of that \"OMG I can see in HD\" effect."
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m0zrwu | How do traffic lights work? Sensors, timing, connection with other traffic lights ... the whole shebang. | Technology | explainlikeimfive | {
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"At the most basic level, the traffic lights have a pre-programmed controller. The controller tells the light how long to show each colour to each direction. If the controller is a bit fancier, it will allow the program to be different at different times of the day or different days of the week. Most traffic lights have detector loops in the pavement (they look like big black circles.) The detector loops are coils of wire that develop an electric current through induction when the metal frame of a car is above them. The controller would adjust the program for when cars are present - for example you might have a green light that only lasts 10 seconds, but it stays green when cars are coming up to a maximum of 30 seconds. Very fancy traffic lights use cameras instead of coils, and they could be networked with other controllers in the city. That would allow for things like setting up a \"green wave\" for emergency vehicles.",
"Telling this from the perspective of dutch traffic lights (or traffic coördination installations (TCI). We've got pre-programmed and detection systems. Both kinds have detector-loops in the roadconstruction and where pedestrians and cyclists use the intersection pushbuttons for them. The difference is in the way the loops are used. In the pre-programmed TCI the loops are used to determine if a green light sequence can be skipped for a direction, because there isn't any traffic waiting to enter. These intersections can also be programmed to skip pedestrians and cyclists until they push the button indicating they want to cross. The TCI's with a detection system have loops reaching out of the intersection to detect if somebody is comming. Depending on what the TCI/intersection owner wants, this system can have loops for cyclists and detectionsystems for pedestrians added, replacing or aiding the pushbutton. I've also heard about some TCI's having weathersensors added so pedestrians and cyclists get their turns faster when it's cold or rains. Thought behind this is that a car/truck-driver can wait a couple of second longer in their warm and dry vehicle while the others get to a warm and dry place faster."
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m10328 | What determines if a compound ends up in your urine or other excrement? | Biology | explainlikeimfive | {
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"The \"most direct\" way for the colour to go is to the feces, this happens as long as the colour isn't picked up in the intestines. If the colour is picked up in the intestines it will go inte the bloodstream. When the blood enters the kidneys it is filtered. Small molecules will be filtered out from the urine, but bigger molecules will stay in the blood. This means that the size of the molecule will determine if it goes into the urine. If the molecule stays in the blood it will eventually be broken down somewhere else, likely the liver, to be excreted or used in another compound. The colour could change a bit if it is processed by different cells in the body, and depending on the concentration. I can't really explain the difference between you and your friends. Maybe your bodies took up different amounts of the compound in the intestines? Maybe the friend who got green pee was dehydrated and therefore the colour got concentrated?",
"Generally water-soluble (hydrophilic) compounds are excreted renally and end up in the urine, whereas fat-soluble (hydrophobic) compounds are excreted hepatically and end up in the feces. Some drugs get excreted via both routes to some degree. They may undergo chemical transformation first to make them easier excrete, in which case the altered chemical is known as a metabolite. The metabolite may or may not share the chemical properties of its parent compound. I don’t know anything about the dye in this case, but there are plenty of factors that could influence the visibility of the dye independent of its manner of excretion, for example urine concentration, which can vary quite a lot depending on fluid intake. Drug interactions or genetics could also potentially play a role by affecting to degree to which metabolism of the dye occurs, assuming it’s a chemical normally metabolized by CYP enzymes in the liver."
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m11k6c | Why do animals play dead? | It seems counterintuitive, you’re just making yourself more easily accessible to the predator and you’re giving them an easy meal. Can someone explain the logic behind playing dead and how effective the strategy is? | Biology | explainlikeimfive | {
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"First, not all threats want to eat you--some will just attack because *they* consider *you* a threat. But if they think you're dead, they no longer see you as a threat and will leave you alone. Second, not all predators are carrion eaters. If they don't hunt down and kill their own prey, they might not consider the dead prey to be suitable food and will ignore it. And third, some animals do not have suitable defenses, against certain predators. If you play dead, maybe it won't rush over and eat you and will become distracted (perhaps by a rival predator), giving you time to escape. Think of a gazelle playing dead to a lion--if a pack of hyenas shows up to challenge the lion, maybe the gazelle can run away, in the chaos.",
"The effectiveness varies greatly depending on the predator. Already-dead animals can be rotting and/or contain parasites. This can be dangerous to eat if you're not equipped to deal with it. Because of this, some predators will not eat dead meat that they didn't just kill themselves. If that's the case, playing dead gives you a chance of the predator deciding you're unsafe to eat and leaving."
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m128ju | How do you purchase and receive energy from a supplier on a particular grid without interfering with other suppliers? | I know that I could choose to buy electricity from a specific provider. If I wanted clean renewable power I could choose a power company that operates hydro plants and they’d take my money every month. But there are other users on the grid and power plants from different companies feed the grid as well so everyone actually draws power from power plants that aren’t operated by their suppliers, except their respective suppliers get paid for the energy used. This wouldn’t be a big deal if a power company could supply all of its customers. If my hydroelectric supplier has a capacity of 10000 MW and the company’s customers suddenly turned on all their devices, leading to a demand that would exceed capacity, some of the demand would be drawn from other suppliers due to the fact that they’re on the same grid. I don’t understand how other suppliers prevent this. How do they make sure Company A’s customers do not take more power from the grid than Company A can provide so Company B doesn’t inadvertently supply Company A’s customers without getting paid? | Economics | explainlikeimfive | {
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"Oh, you can't. I mean, the energy you are using is energy. The grid can't differentiate your green electricity from a coal electricity. Try to imagine it like this, there are 2 water sources that go in the same river. When you take water from the river you can't say for sure whose water you are taking. BUT if you pay the water to supplier A, then supplier A will be required to augment his production capabilities, to meet all the demands that require \"Supplier A\" water. The same applies to green electricity. If supplier G (for green) sells 1 MWh of certified green electricity it means that he has enough renewable production to ensure 1MWh of electrical production. If many users decide that they want to buy their electricity from Supplier G, he will now sell 2MWh, so he will have to increase his certified electrical production accordingly. This means he will have to buy more PV plants or more wind turbines until he can certify that he is producing more energy that the one needed by his customers. Edit: since electricity can't be easily stored. Right now the grid does this calculation year round.",
"They do not care who gets who's power. When you buy power from a certain provider, they have an obligation to produce enough power for you and their customers but that power could be used by anyone. What matters is that buying from them means that *they will produce it*. The system simply keeps track of whether everyone produced what they promised they would. They cannot promise more power than they can make without fines."
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m12h9i | What exactly is an honorary degree when a public figure receives one from a prestigious university. | Lots of people who have been in the public eye a long time tend to receive these honorary degrees from big schools that they didn’t ever attend. What exactly is it? Just a PR move for both parties? Why did Walter Gretzky (father of Wayne Gretzky) have an honorary law degree from McMaster University? I’m generally confused by this. | Other | explainlikeimfive | {
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"It's what it says, purely honorary. It doesn't give you any benefits of the real degree. With a honorary legal doctorate, you still can't practise law. The university just thinks you did something valuable for that field and honours you this way. Its like getting a medal.",
"The original idea of an honorary degree: Sometimes, somebody has contributed a lot to a field of science, without ever having got a degree in it. Maybe a self-taught scientist or technician who became successful and earned the respect of the professors at a university, who then may want to confer the honorary degree to show that they consider him as one of their peers. What it became: Well, as you guessed, more often than not a PR move: Technically, an important politician contributes much to political science by producing a lot of things to discuss. So, let's give him an honorary doctorate for his contribution to the practical aspects of theory and hope that he then supports the university's next funding request."
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m14e56 | The Frequency Response of a linear system ? | I watched the [video]( URL_0 ) regarding this topic from the YouTube channel Physics videos by Eugene Khutoryansky. It helped me visualize how lateral numbers are useful to understand this phenomenon. But it got me also confused about linear systems in general. Can somebody ELI5 by starting of explaining what is a linear system in the first place and what are some real world engineering applications? Thanks in advance. | Physics | explainlikeimfive | {
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"Well linear system is a system where output if proportional to input. So basically output is linear function of input. To make it easier to imagine, system is e.g. electric motor, input is applied voltage, response is your motor revolution per second. So if your electric motor was a linear system, two times bigger voltage would mean two times higher revs. This is just an example to give something to imagine, but in reality its not an linear system. And you can describe basically anything in such way. So system is a plane, input is how much did pilot push the yoke, response is flight angle. Linear systems have wonderful feature, that they satisfy the property of superposition. For understanding this, let as assume that we have some complicated input, and its possible to represent this input as sum of some simple inputs (we have function Fc - complicated, which is equal to F1+F2, which are simple). Then response to the complicated Fc input, is equal to response to F1 + response to F2. This is true for linear system, id does not have to be true for non-linear systems. Knowing this you can combine it with Fourier Theorem (that you can represent any function with sum of series of sin), and you can easily calculate response to different inputs. So simplified flow will be like this: you test your system with e.g. impulse input (impulse contains of very big number of sin functions), and you can tell what is your system response to each frequency. Then you can take this information, and you can calculate output for arbitrary input. You first disassemble your input into sin functions, then you know response for each of those from previous experiment, and your output is just sum of those responses. And what is neat is that you do not do it step by step like I described, those calculations can be done very neatly using complex numbers, many programming languages will have necessary functions available as ready libraries. And one last thing, real system are rarely strictly linear. But we can make some tricks and assumptions, so that we treat our system as liner. This simplifies calculations greatly. In relation to examples from first paragraph we can assume, that while our motor is not linear, in range from 100 to 120 revs it can be approximated as linear. So if what you need is to know motor behavior in this range, then you can go with this approximation."
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m17bd3 | How does a cell know if O2 is being diffused with it or CO2? | I just read about diffusion today and I want to know how does a cell(plasma membrane to be more specific)know if O2 is being passing through it or CO2? | Biology | explainlikeimfive | {
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"Chemistry. Molecular oxygen is very reactive and will rapidly bind with hydrogen given the chance, which is exactly what we use it for. We breathe in oxygen specifically to take away waste protons that would otherwise build up and burn us to death with acid. Carbon dioxide in water disassociates and binds with the water to become carbonic acid so rather than helping to get rid of the acidity it will actually raise it",
"There is no active process involved. None of the cells \"know\" about O2 and CO2. The way it works is this - the mitochondria consumes nutrients and O2 to produce energy (and CO2 as a waste product). That causes the concentration of O2 in the proximity to drop and the CO2 concentration to rise. Then it's all about the chemical process of diffusion - particles tend to move from an area of higher concentration to an area of lower concentration. In blood, there's higher O2 concentration than in the proximity of the mitochondria, therefore O2 moves from the blood to the mitochondria. The reverse goes for CO2. In the lungs the situation is opposite - in the alveoli there's higher concentration of O2 than in the blood and lower CO2 concentration.",
"My vague understanding is this: Diffusion occurs because both oxygen and CO2 naturally balances with itself. So oxygen tends to spread to where there is less oxygen (outside to inside of cell) as with CO2 except there is more CO2 inside the cell then outside of it. As far how a cell \"knows\", not sure but the cell doesn't actively do this. It's passively doing it due to physics/chemistry. I'm no expert so feel free to correct me friends."
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m17ipf | why, when cooking a pizza, mozzarella melts but bread gets harder? What makes them react different to heat? | Chemistry | explainlikeimfive | {
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"There are many reasons, but one is that water evaporates from the dough, while the fat in the cheese turns liquid. Cheese contains fat and water. If you cook cheese long enough, the fat will seperate and ooze out, and the water will evaporate, and it will be crispy and hard too.",
"Every fat has a melting temperature. You may have noticed that coconut oil is solid at room temperature but melts if you scoop it into your hand. Olive oil is solid in a refrigerated salad dressing but liquid at room temp. Dairy fats in cheese melt under oven temperatures. As well, the heat breaks chemical bonds in the proteins of the cheese. Without the protein framework, the cheese loses what was holding it together in solid form. Bread gets crispy primarily because moisture cooks out. That moisture came from water that was added to flour to form the original dough. Bread contains no to little fat. When it does have fat in it, it tends to be olive oil that was liquid at room temperature anyway. Unlike the proteins in dairy (casein), the protein in bread flour (gluten) does not break down until very high temperatures, around 260° C/500° F."
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m17j6p | How do DNA tests trace not only your relatives? | I assume for tracing your heritage they look at DNA segments that are common in certain areas but how do they trace back your lineage if they only recently started DNA testing. Did they dig up all the corpses and swab them? | Biology | explainlikeimfive | {
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"They start with a large sample size of people who already had their heritage known and documented, looked for similarities and differences within those groups, and use that information.",
"There are genetic mutations that arise in DNA over time. While we often associate mutations with disease, the vast majority of those mutations are harmless. Within a geographic region where people have been intermarrying and having offspring for many generations, mutations can get passed along and become quite common within a population. As an example, you might sequence the DNA of living people on Crete and find that they have two or three mutations that occur at a high frequency and are also unique to their population. If someone in Australia or the United States is found to have the same mutation, it may be because they have an ancestor from Crete. I say “may” because it is not a certainty. The type of mutation and its frequency in the population allow scientists to assign a probability to the likelihood of someone having ties to a geographic area.",
"There are three parts to using DNA for genealogy. 1. Y-DNA is passed from father to son. You have an identical copy of your father's Y-DNA. He has an identical copy of his father's Y-DNA...and so on. However, Y-DNA does slowly mutate over many generations. This has created Y-DNA variations among men. 2. SURNAMES (also known as Family Names) are passed from father to son. Surnames began somewhere around 1100AD in Europe. 3. Standard \"old fashioned\" genealogy. Usually, documentation (census records, birth records, baptism records, tax records, etc.) can trace male ancestors back 200 or 300 years. Some families have maintained their own genealogy better than others. Occasionally, a family will have documented its genealogy back 500 years or more. In very rare cases, the genealogy goes back more than 1000 years. TO ANSWER YOUR QUESTION: Suppose Mr. takes a Y-DNA test. The Y-DNA test reveals a match with Mr. A. If there is a match, than Mr. A and Mr. B have a common male ancestor. If Mr. A and Mr. B have the same surname, you know the common male ancestor likely lived after 1100AD. Then, Mr. A and Mr. B get together and try to find the link, usually using old-fashioned genealogy by looking at court records, census records, deeds, etc."
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m17mu1 | Why are international treaties and agreements so long (as in the length of the document itself)? | What makes these so lengthy? One example is [Maastricht Treaty]( URL_0 ) (signed in 1992 that forms the basis of today's European union) which is hundreds, if not thousands of pages long. | Other | explainlikeimfive | {
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"Because everyone involved has lots and lots of \"yeah, but *what if...*\"s that need to be specifically addressed. Otherwise a situation could come up in the future that's unclear, and that could become messy. As the number of signatories grows, the number of \"what if\"s that need to be clarified grows, and the more specific they need to be.",
"Because humans are imperfect, and when they negotiate these things they're trying to make them as clear as possible to avoid ambiguities and misunderstandings that can cause conflicts or loopholes that someone can exploit. And the best way to make them clear is to make them specific, and to make them specific you need to write out a lot of stuff. Sort of like how early on in Russian history the law just said that \"the first male in the ruler's family becomes the heir to the crown\". Except they didn't know if \"first male\" meant \"son\" or if it could apply to brothers or even uncles.... so it led to some power struggles when the ruler passed away. Writing out specific situations and ways to do things helps avoid crap like that. It's still inevitable because there are always still multiple ways to interpret things. But that's usually why they have committees that are meant to resolve disagreements.",
"The Masstricht Treaty is very long because it is very complicated and contains hundreds and hundreds of little compromises and exceptions to rules. Some treaties, like the [Japanese Instrument of Surrender]( URL_0 ) that ended WW2 are *very* short. Turns out when one party has all the leverage a document can be quit brief."
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m17w2b | Why are circuits on boards? | Technology | explainlikeimfive | {
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"Before circuit boards were a thing, designers had to scramble wires together in a big ugly mess. I don't have all the details of this organization, but imagine a bunch of tangled up wires, capacitors, etc. Circuit boards not only rid of those messy wires, but they're super compact, which allowed computers back then to shrink down (along with other inventions like the silicon transistor). Edit: [I found the image I was looking for.]( URL_0 ) Edit2: With Circuit boards came cheaper computers, which meant they could be mass produced and sold to consumers. Paving the way for today's computers and even the Internet and the www.",
"Because it's way easier to manufacture this way, and therefore nearly all modern parts are designed to be put on printed circuit boards. That wasn't always the case, up to the 1950s point-to-point wiring was common. It looked like this: URL_0 This is basically impossible to automate, and was done on long assembly lines by (typically) women. In those times, labor was cheap and parts were expensive, so this was economically viable. It was prone to faults though, it's not uncommon at all for collectors of vintage gear to find connections not ever been soldered. They just barely had contact to work on the testing station. Then came printed circuit boards. The start out as a copper-clad board and all the copper not needed for connections is etched away in a quite complicated process, which I will not explain here. They started to be used in 1930s, but really became mainstream in the early 1960s. The early board were still populated (parts were stuck through holes) by hand, but already soldered automatically by moving them over a bath with molten solder (wave soldering, still in use today). From the 1980s onwards, even the placement of components was done by robots and then the whole board is put in a special oven to melt the soldering paste which was put on before the parts. You get a finished board in minutes, with a precision not possible by hand.",
"All the branches were taken? Seriously tho, because it's easy to design in 2d (draw by hand) and mass produce with minimal waste and effort. Also it's far more durable and safe than wiring."
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m17y1p | What is exactly happening when AC power is being converted to DC energy? | Technology | explainlikeimfive | {
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"There are electronic components called diodes. These are sort of like one-way streets for electricity. If you try to pass AC through one of these, only half the wave will get through, say the positive half. This is called a *half-wave rectifier*. Now, if you do two of these, one in each direction, you can have one stream that gets the positive halves of the waves and a second that takes the negative half. You can then combine these together using some more diodes so that you basically get the full wave, but with all the negative bumps flipped to positive. This is a *full-wave rectifier*. Sometimes, your circuit uses 3-phase power. There are 3 wires running AC, but ⅓ of a cycle out of step with each other. If you fully rectify this, you get a signal that's just a slightly bumpy version of DC. Regardless of single or 3 phase, the next step is to smooth things out as best you can. This can be done using a *low-pass filter*. LP filters let through signals that don't vary much, and are resistant to quickly changing signals. If you've got a sound system with a woofer and a tweeter (low and high speakers), there's an LP filter making sure the woofer only gets the bass. A simple LP filter is just a coil of wire, known as an inductor. When you pass a current through it, it generates a magnetic field. This field is resistant to changes in the current. It store energy, and when the supply drops, it gives off some of the stored energy to stabilise it. When the current tries to increase, the inductor takes in some of that energy to 'charge up' the magnet. This means the current coming out the inductor will be smoother than what went in.",
"Imagine the energy as some water. Now imagine a big glass of water - something like a water tank full of water with a hole in the bottom with a continuous output flow. This is your D.C. current. Now, imagine that you bury this water tank in the sand on a beach and that each wave that arrives fill it a little bit (and you still have a the water going out of this tank). Well, the waves are you A.C. current entering in pulses in your tank. When an A.C. to D.C convertet is designed, its basically a calculation on how much you can bury your tank in the and the size of your tank (voltage and capacitance value for the capacitors) in order to have a more or less stable output flow out of the tank - also depending on the frequency of the waves arriving.",
"The most important part is the bridge rectifier. We use little electrical one way valves (diodes) so that no matter the input voltage (+ on top or on the bottom) you always get positive voltage on one wire and negative on the other, [the wiki has a nice GIF showing this]( URL_0 ) Generally we will put a big capacitor on the output to store the energy. This capacitor takes the ups and downs that are coming into it and stores the energy so it just sits at the peak voltage. Now you've got a constant voltage that you can use to power things or can step down to a low voltage using a DC-DC converter so you can get 5V for your phone or 3V for a little micro controller. Old style boxes, the really heavy ones, used to put a step down transformer in the front to bring the peak voltage down from 170V (on US 120V power) to the 12 or 24V that they were needing in the end and then they ran that lower voltage through the rectifier and into the capacitor. These are simple and don't require any fancy electronics but they do require about 5 pounds of iron in the transformer core. Electronics are wayyyy cheaper these days than they used to be so its now cheaper to use the fancy electronics for the DC-DC converter than a big transformer meant for stepping down line voltage at just 50/60 Hz",
"This is one of those things that's much harder to explain with just words, so I'm going to invest about a hundred seconds in MSpaint to make some bad images that will help a great deal. First off, DC, or direct current, is electricity that flows in one direction. AC, or alternating current is simply electricity that switches directions on a regular basis. Household AC switches 60 times per second. AC starts out looking like this on a device called an oscilloscope. You can see it smoothly changes from one direction (positive, or +) to the other (negative, or -): URL_0 Using a pretty simple circuit, you can 'cut off' one side and send it all in one direction, so that it looks like this: URL_1 That circuit just uses a few components called diodes, which only allow electricity to flow in one direction through it. The problem is that it isn't very smooth. It's more like very fast bursts of DC current, so we need to try and fill in those gaps. To do that, we use a component called a capacitor. That device is like a tiny battery. When there is current going through it, it charges up. When there isn't, it discharges. We can use these to sort of fill in those gaps, like so: URL_2 The better a job done by the capacitors, the more it looks like a straight line, the closer to pure DC it gets. URL_3 There are more modern ways of converting AC to DC with much more accurate results using transistors, but this classic way has been around for a very long time.",
"You use some diodes and a capacitor to \"rectify\" the signal. They are arranged in such a way that when the voltage is positive, current flows, but current is blocked by the diode when your AC voltage is negative. The capacitor then starts discharging some stored energy it got when the signal was positive, and that keeps your DC voltage constant.",
"AC is electricity that goes from positive voltage to negative voltage over and over again. Each time it does this, we call that a cycle. The number of cycles per second are called hertz. DC is electricity that is always a positive voltage. There are 2 components you need to know about to converting AC to DC. The first is called a diode. A diode only allows electricity to flow one direction through it. Since AC voltage goes positive to negative, the current flows backward and forward. We want to stop that. The second component is a capacitor. More on that later. So, imagine a sine wave of electricity, that is AC. The diode chops off the bottom half of the wave, or the negative part. What you have now is like hills of positive voltage with 0 volts between them. This is called pulsing DC. We want to make the pulses smooth, so that the voltage is constant. This is where the capacitor comes in. The capacitor charges and then slowly releases that charge. So it charges up from the pulse of DC and the releases a longer slowly decreasing voltage that bridges the gap between the hills. Its still not perfectly constant, but its much closer to a constant voltage and most DC items don't really care about the noise. Extra credit: there are circuits you can build called full-bridge rectifiers that flip the negative part of the wave to positive and add it to the positive wave so that there is no time when the voltage is at zero and the hills are closer together. This is both more efficient and has less noise. These are made with 4 diodes in a clever arrangement."
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m17yqq | if diamonds are just carbon pressed together, why are they clear when stuff like coal is black? | Chemistry | explainlikeimfive | {
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"Because diamonds aren't \"just carbon pressed together\". They are carbon atoms in a very specific cystalline formation. At an atomic level the carbon atoms are in a very specific and rigid shape, one whose shape allows the passage of visible light through it. In contrast, just normal coal has the atoms in a rather random collection, one where light cannot pass through it and instead it gets absorbed."
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m189lo | Why does a bladder distention usually lead to Autonomic Dysreflexia? | What is the pathaphyssiology behind this? | Other | explainlikeimfive | {
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"The bladder distention is the trigger, but it is the spinal cord injury that is the cause. I really don’t know how to explain this to a 5 year old, but basically: You hurt your back — > signals from the brain have a hard time getting past the injury — > your bladder gets full and starts sending signals that it needs to empty — > the nerve impulse for that cannot pass the spinal injury — > the brain gets angry and starts sending out a bunch of signals— > these signals cause your blood pressure to rise — > your heart sees the BP increase and slows down"
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m18wjc | What does “based” mean? | Other | explainlikeimfive | {
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"I’m pretty sure it means to have a somewhat controversial opinion without giving a shit about the current trend and what others would think of it. Saying “Based” is like acknowledging it and supporting it.",
"I think it's easier to understand with a bit of history. Originally, the term was used to describe someone high on crack, or acting as if they were (in this case \"based\" being related to \"freebase\"). Rapper Lil B then adopted the term to mean being yourself without caring what other people think. Kind of like, \"you can call me a crackhead if you want, I'm just being myself\". In his own words: > Based means being yourself. Not being scared of what people think about you. Not being afraid to do what you wanna do. Being positive. When I was younger, based was a negative term that meant like dopehead, or basehead. People used to make fun of me. They was like, \"You're based.\" They'd use it as a negative. And what I did was turn that negative into a positive. I started embracing it like, \"Yeah, I'm based.\" I made it mine. I embedded it in my head. Based is positive. Then 4chan got hold of it, and like seemingly everything 4chan gets a hold of it came to be used as an instrument of alt-right memery to express approval for people \"telling it like it is\" (i.e. saying something anti-woke or just flat-out racist). Now that both alt-right and alt-left use the term, and it has passed into more general discourse, it has in a certain way gone back to Lil B's meaning of acting like you don't care what others think, and is a means of expressing approval for such behaviour."
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m19zus | What are some of the problems that zinc-ion batteries have, over lithium ion? | I've read in an article that aqueous zinc ion batteries are better, safer, and can store up to 5 times the charge of lithium ion. What are some of the major concerns that has made zinc-ion batteries not so much popular? One thing that I was able to get from the article was that it can last for only 100-200 cycles? Edit: 5 times cheaper. Sorry for the typo, I just skim read that article, while researching on Li alternatives. | Technology | explainlikeimfive | {
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"Where are you seeing this 5 times charge figure? According to Wikipedia (obviously not the be-all and end-all, but still) zinc-ion batteries are around 450 Wh/l energy density, while Li-Ion are between 250 and 693, which is pretty much the same ballpark.",
"(Keeping it simple...) Zinc has long been used as a material for batteries - and very successfully for certain applications. Zinc-Air are extremely common for small button cells as primary batteries. Almost \\_anything\\_ will react with zinc and via ionic exchange produce electricity - kiddies use lemons and galanized (zinc) nails even! The problems really arise with the secondary cell process where there is a need to reverse the process to store energy. Unfortunately much as zinc wants to convert to electricity one way, the reverse reactions are often poisoned or very inefficient, and so the cycle life becomes very short due to this poisoning or loss of reactive zinc. Lots of research has been done and will continue into trying to damp these issues, as zinc is (comparatively) safe, and certainly very plentiful and inexpensive. It also has a relatively low environmental contamination potential compared to other metals. Unfortunately some of the chemicals used in zinc secondary reactions are not so friendly though - such as zinc - bromine secondary cells. Zinc/alkaline/manganese-dioxide battery's are one example of smaller successful secondary zinc batteries, but these too have limited cycle lives for the same reasons as above. I hope this helps. :-)"
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m1ae5t | Why is there significant positional variation in mobile data speeds even inside a single room? | Technology | explainlikeimfive | {
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"text": [
"Mobile phone signals are typically in the hundreds of MHz to a few GHz range, which means the wavelengths are something like 10-40cm. Objects roughly that size can reflect or absorb the radio signal, causing blank spots and interference (both constructive and destructive) over a range of a few meters. If you're outside with no major things between you and the antenna you shouldn't see much variation, but inside a room with other radio noise sources, potential blocks, and potential reflectors you could have a \\*very\\* complicated radio situation that varies from point-to-point over just a meter or two."
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m1aeqm | Regarding cookies on website: What is legitimate interest and how do companies get the status? | Also, what rights to store cookies do they have when you object to their regular cookies but do not tick off the legitimate interest option? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Most companies don't actually do this correctly. There are two different data privacy laws in the EU which potentially govern cookies, and companies get these confused. The main data privacy law in the European Union is GDPR. Under GDPR, in order for data processing to be lawful, it needs a \"Legal Basis.\" Basically, a justification that is legally recognized as a valid reason to process someone's data. There are six (6) possible choices for the Legal Basis for a processing activity. Some of these are straightforward, like \"Performance of Contract.\" If I purchase something from Amazon, they need my shipping address to actually send it to me. Makes sense. Or \"Legal Obligation.\" There's a law saying they have to keep a record of credit card transactions for seven years. Also makes sense. The most open-ended Legal Basis is \"Legitimate Interest.\" This legal basis basically says \"we have a reason for processing your data, and we promise it's a good one and doesn't invade people's privacy too much.\" The vagueness is basically necessary for many businesses to operate, but also the most open to abuse. Fraud Detection is a common example of something that falls under Legitimate Interest and has a reason to exist. Legitimate Interest implies some extra obligations unique to that Legal Basis. For example, the company *is required to tell you the specific Legitimate Interest*. They can't just say \"Legitimate Interset.\" They have to say \"our Legitimate Interest of fraud detection\" or whatever it is. Processing under Legitimate Interest is also subject to the Right to Erasure (more commonly known as the Right to be Forgotten), which is not the case for e.g. Performance of Contract. A company should perform a Data Impact Assessment before invoking Legitimate Interest, and this is reviewable by regulators. If they did a bad job balancing their interests against the privacy of the data subjects, they can be subject to fines. However... Website cookies are *also* governed by the ePrivacy Directive. This law has no concept of Legitimate Interests. Either a cookie is strictly necessary for the website to function, or it requires consent. If a company invokes Legitimate Interest to justify their cookies, then they are violating the ePrivacy Directive. (Due to how EU law works, the ePrivacy Directive has different names in different countries. E.g. in the UK it is called PECR (and is still in effect post-Brexit))."
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