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7h21am | How can something smell sweet but not taste sweet at all? | I'm drinking some cinnamon tea that smells lovely and sweet but there's always no detectable flavour to it at all. I thought that smell and taste where closely linked so I was wondering how I had been duped. | Chemistry | explainlikeimfive | {
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"That's because there are some tastes which you don't taste on your tongue. Instead you smell them, and thereby \"taste\" them. Some examples of this could be chocolate, coffee and most spices. You only have the ability to taste 6 different tastes and variations thereof, but your nose is a lot better at it, and allows you to distinct different foods. Try holding your nose and taking a piece of chocolate. It probably tastes sweet, but the cocoa taste is almost gone (this is because your mouth an nose are linked in the back of your mouth, so you can often still taste it a bit)",
"Also it doesn't actually smell sweet. Go smell pure sugar, it's almost odorless. The reason you think it smells sweet is because it's an aroma you typically associate with sweetness, kind of how vanilla extract smells \"sweet\" and delicious but tastes like stale ass. The aroma isn't sweetness, it's vanilla, we just always put vanilla in sweet things and associate the two."
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7h27yf | Why haven't we been back to the moon? | Economics | explainlikeimfive | {
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"Mostly because there's not much interesting there it turns out, and more questions we do have can be done better by robots than by sending people.",
"Is new scientific data from the moon worth the cost of sending people up there again? They're not likely to find anything there to greatly enhance our knowledge of the universe or our solar system. Mars is a much more interesting destination to get scientific data from."
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7h29sg | How do we pick up a language when we are youbg and dont know any language | Biology | explainlikeimfive | {
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"The brain tries to combine actions and reactions with words as well as copying parents. When your mum points at herself and says \"Mama\" enough times the brain will remember that and when you yourself says \"mama\" she will react to that. Boom! You just learned that \"mama\" gets your mothers attention and that when your parents point at something and says a word, that word is the name of that thing. Learning a language also includes trial & error, but the basis is built upon observing the parents"
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7h2ns1 | How does different data traveling on the same cable not get lost with all the other data? | Technology | explainlikeimfive | {
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"Data is encapsulated into packets with headers and trailers that identify it. Sometimes it does get lost though. When 2 devices establish a connection, they decide on packet numbering. If I send you a packet that says it contains data 1500 - 1600 you expect that my next packet starts with 1700. If it doesn’t, then you your response to me is essentially “I need 1700”."
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7h2ooa | How is NASA sending commends to a probe that is 13 billion miles away from the Earth? | Physics | explainlikeimfive | {
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"Radio and other electro magnetic waves can travel pretty much forever in space. We can see stars that are billions of light years away for example. There is the problem of getting the signal to to escape the interference of Earth's magnetic field, but we have the technology to do that for decades, the first radio signal that left the atmosphere was the part of the 1936 Olympics. and to receive data we need an antenna sensitive enough to pick the signal up from background noise, which again has existed for decades. The real engineering problem with the distances involved is that the signal will take time to reach the probe, and the probes signal will take time to reach us, this problem is solved by designing a probe to need as little input from the ground as possible for normal operation."
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7h2rfn | NASA Engineers just communicated with Voyager 1 which is 21 BILLION kilometers away (and out of our solar system) and it communicated back. How is this possible? | Seriously.... wouldn't this take an enormous amount of power? Half the time I can't get a decent cell phone signal and these guys are communicating on an Interstellar level. How is this done? | Physics | explainlikeimfive | {
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"> I can't get a decent cell phone signal and these guys are communicating on an Interstellar level. Mobile phones work off UHF (Ultra High Frequency), so the range is very short. There are usually signal repeaters across a country, so it gives the impression mobiles work everywhere. > wouldn't this take an enormous amount of power So, not really, as long as there is *nothing* between Voyager and the receiving antenna (usually very large). As long as the signal is stronger than the cosmic background, you'll pick it up if the antenna is sensitive enough. So the ELI5 version of this would be : - Listening to a mouse in a crowded street. Versus - In an empty and noise-less room, you are staring at the mouse's direction, , holding your breath, and listening for it. EDIT: did not expect this to get so up voted. So, a lot of people have mentioned attenuation (signal degradation) as well as background cosmic waves. The waves would very much weaken, but it can travel a long wave before its degrades to a unreadable state. Voyager being able to recieve a signal so far out is proof that's its possible. Im sure someone who has a background in radiowaves will come along and explain (I'm only a small-time pilot, so my knowledge of waves is limited to terrestrial navigation). As to cosmic background radiation, credit to lazydog at the bottom of the page, I'll repost his comment > Basically, it's like this: we take two giant receiver antennas. We point one directly at Voyager, and one just a fraction of a degree off. Both receivers get all of the noise from that area of the sky, but only the first gets Voyager's signal as well. If you subtract the noise signal from the noise + Voyager signal, what you've got left is just the Voyager signal. This methodology is combined with a lot of fancy error correction coding to eliminate reception errors, and the net effect is the pinnacle of communications technology: the ability to communicate with a tiny craft billions of miles away.",
"They used a very large dish to focus the transmissions into a narrow beam. The bigger the dish, the greater the effective power. A 70M dish has a gain of around a million (depending on the frequency) . They also used very low bit rate communications. The usable bit rate is highly dependent on signal to noise ratio. They do use high power on the Earth side, but the spacecraft has only a few watts, and a small dish. The Earthbound receivers use ruby ~~masters~~ masers cooled in liquid helium to get the lowest noise. Edit: changed a word",
"One thing that they do in order to make communication with these spacecraft more reliable is to send the same batch of commands multiple times, each with a very slight frequency offset. This accounts for any relative velocity variation between Earth and the spacecraft, which may receive 3 of 5 commands sent, for example. The signals from the Voyagers are not strong - they are, in fact, weak compared to the background noise, but clever software algorithms have been developed which identify and isolate these transmissions.",
"1. The electronics on board was state-of-the-art at the time of launch. 2. The electronics had to be tough and a lot of protections had to be added so it could survive cosmic rays and other hazards. 3. The electronics was way simpler that it would be if built today. Less complexity less stuff to fail. 4. Because the hardware is simple, the software it runs is simple, compared to today standards, so, less or no bugs, less motives to fail. 5. Voyager was built with a lot of redundant components. So, if one part is not working well, there is another wan that works and the whole thing keep going. But obviously, a lot of stuff is broken by now. Space is hostile as hell and time is unforgivable for any machine and organism. It can last long but it will fail eventually forever. The only hope is that some civilization finds our treasure chest one day and see they are not alone.",
"Firstly, its not \"interstellar level\" it's 19 light hours away and the nearest star is 37168 light hours away (4.243 ly). Secondly, NASA has access to giant radios and receivers. One 34-meter (112 ft) diameter High Efficiency antenna (HEF) Two or more 34-meter (112 ft) Beam waveguide antennas (BWG) (three operational at the Goldstone Complex, two at the Robledo de Chavela complex (near Madrid), and two at the Canberra Complex) One 26-meter (85 ft) antenna One 70-meter (230 ft) antenna (70M) Voyager has a 3.7-meter (12 ft) diameter parabolic dish high-gain antenna to send and receive radio waves via the three Deep Space Network stations on the Earth. Your cellphone antenna is about as long as your phone Here you can see what all the DSN arrays are doing - URL_0",
"There isn't very much in the way of it, since it is mostly empty space between there and here. There is a high latency, of course. Your phone signal can't work with high latency since it is designed for quick communications, and it is prone to errors caused by other nearby signals.",
"They use a system called the Deep Space Network that uses huge satellite dishes located all over the world. You can actually see which spacecraft are connected in real-time here: URL_0",
"Reposting my own top comment from [one of the last times this question was posted]( URL_0 ): > Some other commenters have covered really well how it's still transmitting, so I'll cover a bit of how we're receiving. The signals Voyager transmits are really weak when they get here, and there's a lot of noise in the electromagnetic spectrum, so the signals are way weaker than the noise. \"But wait\" you might say, \"if the signals are weaker than the noise, how can we hear them?\" It's a challenge comparable to hearing your friend whispering from across a room full of people talking. We came up with a really clever way to hear them, though. > Basically, it's like this: we take two giant receiver antennas. We point one directly at Voyager, and one just a fraction of a degree off. Both receivers get all of the noise from that area of the sky, but only the first gets Voyager's signal as well. If you subtract the noise signal from the noise + Voyager signal, what you've got left is just the Voyager signal. This methodology is combined with a lot of fancy error correction coding to eliminate reception errors, and the net effect is the pinnacle of communications technology: the ability to communicate with a tiny craft billions of miles away.",
"Scientific systems engineer here... It's not about the amount of power needed to generate and broadcast the signal from the instrument, it's about the massive infrastructure needed to *hear* it. As such, NASA has built a massive ground system called Deep Space Network that's designed specifically to communicate with interplanetary spacecraft. Three ground stations in Australia, Spain and California coordinate their huge arrays of dishes (dozens at each site, each one with its own 70m dish) to send and receive signals to basically all of the exploratory research instruments in the solar system. In the case of Voyager, it takes something like 30 hours just to get a signal there and 30 hours to get it back, but as long as it's RTG can create enough energy to power it's high gain antenna, we'll still be able to talk to it.",
"We know where Voyager is, it knows where the Earth is, and we built extremely large satellite dishes to be able to pick out the signal from the background noise.",
"Sending radio waves long distances is hard, but to help they use a dish to concentrate the antenna's output into a beam rather than out in all directions. This greatly magnifies the signal in the direction that the dish is pointed. But this then requires the spacecraft to be very accurately pointed at Earth, or the beam will miss the Earth and we would not receive the signal. So the spacecraft uses thrusters, basically tiny rocket engines, to turn the craft to always point the dish towards Earth. Voyager has two sets of thrusters, and the set that they normally use to point the dish are running out, so they tested the other set to make sure they can start using them for pointing the dish. The test was successful, which means they can still point Voyager towards Earth for a few more years. For power, they use plutonium. Plutonium is radioactive and heats up when you put enough of it in one container. You can make electricity if you put something hot - the plutonium - and something cold - space - together, which powers the radio dish, as well as the rest of the spacecraft. Unfortunately, the plutonium makes less and less heat over time and will eventually no longer be able to make enough heat to power the spacecraft and the antenna. When this happens Voyager will no longer be able to talk to us, or run its computer. It's lifetime will be over.",
"There are two factors that impact how far apart you and someone else can communicate How loud can you shout? How quiet of a sound can you hear? Voyager is little so it can't shout very loud, and it can't hear extremely quiet things so the Earth station makes up for it. NASA uses very large and very powerful satellite dishes to blast transmissions at Voyager, and extremely large and sensitive antennas to listen to the really quiet messages it sends back The antennas on Earth send about 20 kW(73 dBm) of power at Voyager for it to be able to hear the message. Voyager sends back a 20 W signal and by the time it arrives it is at an extremely low power level ( < -240 dBm, no i can't convert that into normal watts its too damn small)",
"I didn't read all the comments before replying, so I apologize if anyone has already mentioned this, but a key factor in digital communications is the energy in the received signal, not just the power used to transmit it. These two quantities are related by the amount of time it takes to transmit one bit of information (and other things like distance, and interference). If you multiply power by time you get energy. In your typical cellphone link you're transmitting a lot of information very quickly (i.e. Mbps). When you compare that to the amount of data it takes to, for example, command a microthruster to turn on, you're looking at a command sequence that's only a handful of bits, maybe a kilobit. And you can afford to wait seconds (I'm not talking about a delay now because that also takes a while, but the time it takes to receive the message from when the first bit arrives to when the last bit arrives at the receiver). In addition to this, as others have said, the sensitivity of the receiver is very good (because it's cold, it's looking mostly at cold space, and it has a very narrow beam aka high gain), and there is no obstruction or significant sources of interference. However, simply a lower data rate helps to receive a weak signal more strongly. Hope that helps. (I am an electrical engineer who works for an aerospace company designing communications satellites.) TL;DR say it slow and it's easier to understand from far away. edits: clarity and adding the TL;DR.",
"my real question would be: how much is the latency? Like, they send a message and how long does it take to go to the other side?",
"Also What protocol does it use? I imagine tcp would be pretty bad with the rtt.",
"Curious about the affects the theory of relativity would have on the actual amount of time the satellite has been out there in space. This is to say that if the satellite is moving at a high speed and is experiencing time moving slower when compared to ours here on earth, would that mean the satellite has really not experienced 40 years of time but instead has only undergone a significantly smaller amount of time with which it’s parts can age?",
"I work for the Deep Space Network (DSN), which is the group responsible for communicating with all of the unmanned spacecraft NASA has launched. We use high powered transmitters on large radio telescopes for outbound communication. Then for inbound communication, we amplify the signal, while removing noise at the same time. We know how the inbound signal should look and so we can remove most of the noise and amplify the rest. Very simple response but, I can provide links and additional detail as needed.",
"> Half the time I can't get a decent cell phone signal Your cellphone isn't communicating with [this]( URL_0 ). If it was your signal would be 5 bars at all times",
"Simple answer: digital signal processing Analog waves get messy and lose information at long distances. With the help of digital signal processing, data can travel million miles and the information still stays the same and we extract it from the garbage. Source: EE who works in telecom",
"Could I send my own radio signal to voyager ? EDIT: phrasing",
"The earth rotates constantly though. So if it's a single straight beam signal coming back in a tunnel, how do we maintain connection?",
"They should be sending Probes out every year in the same direction so that they can have a string of them communicating with each other back to us."
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7h2skt | Why does sleeping for too long make my brain feel more foggy than not sleeping enough? | Biology | explainlikeimfive | {
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"When you sleep you go through certain cycles of sleep. The standard cycle from light sleep to deep sleep and back is roughly 90 minutes. When you over sleep there is a higher chance that you wake up while still in deep sleep cycle. There is very little brain activity during this period which is why when you wake up you feel \"out of it\" your basically waiting for your brain to kick back in to normal function. This is also why naps during the day should be either short 20 minutes so that you never enter deep sleep or 90 minutes so you make it out of that deep sleep and do not feel that same fogginess"
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7h2t4u | Why are public toilet seats in the show of a "c", and not "O" like the ones in homes? | Technology | explainlikeimfive | {
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"It's so that males don't have to pick up the toilet seat in order to urinate. In the circle shape, there is a possibility for dripping on a seat to occur. In the U shape, the drips just fall into the bowl.",
"The missing piece is by your genitals. No one wants a public toilet seat to touch their genitals."
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7h2w9v | What specifically is so bad about the tax bill passed by the senate? | Economics | explainlikeimfive | {
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"It's almost 500 pages long. Literally nobody voting on it had time to actually read through the whole thing. They voted on something that literally had hand-written notes on the margins of pages.",
"Kind of piggybacking off of this, but what are some of the economic consequences that this tax bill would cause?",
"The tax cuts are all for the wealthy. The theory - tested in the past and failed - is that if you give money to the rich they will spend more and improve the economy. This never works. Trickle down is not real. Rich people save the money and get richer. So the vast majority of Americans will receive no tax cuts and end up worse off. I can not think of a single good thing about this bill unless I'm rich. I would love to hear the contradicting argument."
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7h2yry | Why over the counter pain medication helps with minor pain but not major pain | Biology | explainlikeimfive | {
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"Over the counter pain medication works by raising the threshold for a stimulus to be felt as pain. Stimuli that are more intense can surpass this higher threshold, being felt as pain anyway. These kinds of medication also have a ceiling effect, meaning higher doses will not yield stronger effects after a certain point. Opioids, on the other hand, work by directly triggering receptors in the patients brain that diminish the sensation of pain, and do not present said ceiling effect, meaning one can always use a higher dosage to get stronger effects (until you OD and die, that is)",
"It does help with major pain. Tylenol is extremely effective in managing post-operative pain. The fact that it's OTC gives people the perception that it is not very effective. It's not going to knock your ass down like dilaudid, but it still works very well."
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7h3etg | Why do some websites still use "www." before their domain name and some simply don't? What's the purpose of it anymore? | Technology | explainlikeimfive | {
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"The \"www\" is what's termed a \"subdomain\". Originally, the \"www\" (which stands for \"world wide web\") was used to indicate that you wanted the web server for the domain you entered in, as opposed to something like their FTP server. Subdomains are still used today. For example, you can go to \" URL_0 \" to get to Google Maps, or \" URL_1 \" to get to gmail. But generally it's assumed that if you don't specify any subdomain, you're probably interested in the domain's main webpage, which is what the www is for, so it's often redundant, and thus not required.",
"It doesn't really serve any purpose anymore, except that some people expect it to be there. You need to make both URL_0 and www. URL_0 work because people will type both into their browsers, but it doesn't make much difference whether you choose to have URL_0 redirect to www. URL_0 or the other way around.",
"There are also some technical reasons for it to do with managing big websites. There's heaps of info at URL_0 but basically, managing your domain well often requires splitting it into manageable pieces. It's harder to split things up if you haven't used some sort of subdomain - and that's what \"www.\" is. A small personal website probably doesn't need www."
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7h3h0o | Why Does Mint Make Everything Seem Colder than it Actually is? | Biology | explainlikeimfive | {
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"It has an effect on the same nerves that detect cold. It's similar to why something spicy feels \"hot\" when there's no extra heat on it."
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7h3i72 | What is a strangelet and why is it dangerous when it comes in contact with matter? | Physics | explainlikeimfive | {
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"A strangelet is a hypothetical particle that contains an equal number of up, down, and strange quarks. If it were to come into contact with regular matter it is theorized that it will turn it into strange matter. If this can happen then that matter will turn other matter into strange matter, ending all life on earth (if it were to happen on earth)"
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7h3kht | Why does hitting some machines help temporarily "fix" them? | Other | explainlikeimfive | {
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"As Shifty said, sometimes hitting the thing causes what was wrong, as in something being loose, to jump back into place. Wires, fuses... hitting them helps them connect again. There's actually a word for this! It's called 'percussive maintenance', which means \"The use of physical concussion, such as a knock or a tap, in an attempt to make a malfunctioning device or person work.\""
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7h3sa1 | what are blue collar and white collar jobs? Are there any other collars? | I always see the terms 'Blue collar' and 'White Collar' jobs, but I'm never 100% sure what they refer to? I think Blue Collar is things like mechanic etc and I assume it is due to the standard overalls associated with said jobs? But what does that make White Collars? A lot of work places have people wearing white collars, does it always refer to the type of clothes they wear? Follow up, are they any other *colour* collar jobs, like Green collar? If so what are they and what do they refer to? | Other | explainlikeimfive | {
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"Blue collar is manual labor. White collar are Professional office jobs. Some people also refer to grey collar which are service jobs that fall in the middle.",
"There are historical terms. White collar workers were office workers, educated, upper society, etc. Blue collar workers did factory jobs or in the mines. Blue clothes hid the dirt and sweat stains. White collar shirts are for people who don't do dirty jobs.",
"Blue collar worker does jobs that involve manual labor, like construction worker, electrician, plumber, factory worker, etc. White collar refers to people who work jobs in offices, like accountants, lawyers, businessmen, etc.",
"There are all sorts of collar designations: URL_0",
"Blue collar refers to manual labor, like factory jobs, construction, mechanics... because they historically wore blue chambray or denim coveralls or work shirts. White collar jobs are office jobs where people historically wore white dress shirts with suits — things like accountants, lawyers, bankers, managers. Knowledge jobs. There is also the term “pink collar” that refer to historically female jobs like nursing, childcare/early education, secretaries and so on"
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7h3sjq | Why do we get a runny nose when we tear up? | Biology | explainlikeimfive | {
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"> Why do we get a runny nose when we tear up? Because our tear ducts drain into our nose. There are a whole network of sinus tunnels in our face which are connected."
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7h40ia | How is Ceramic Body Armor Made? | There is a hard strike face, then a fibrous layer, then a hard ceramic layer, right? | Technology | explainlikeimfive | {
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"Ceramic body armor is usually covered by kevlar and has a metal plate in the center of 2 ceramic plates. So when a bullet hits the ceramic it breaks and causes the bullet to expand and slow enough to stop it before entering the person. Fun fact: military strike plates (ceramic body armor) are rated to stop 5 7.62 rounds within a 4 cm triangle!"
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7h495o | Why is the latest tax bill being called the "tax scam bill"? How will it effect most americans? | Economics | explainlikeimfive | {
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"The Senate version of the bill, to fit the Senate's rules for budget bills (to be able to pass it without any Democrats) has most of the tax cuts for individuals expiring after a few years. Between that and some more obscure changes about how it adjusts for inflation, it could lead to a tax increase for many lower and middle income families after the cuts expire in 2025. So while most people would get around a 1% increase in after-tax income for a few years, virtually no one outside of the top 1% would be saving any money [compared to the current tax code]( URL_0 ) in 10 years. The tax cut for corporations would be permanent, but the wage increases and new jobs that Republicans promise would come with it seem unlikely to materialize according to [actual surveys of companies]( URL_1 ) who say they would just use their savings to pay off debt and buy back stock. The House version of the bill is probably better for the average person because the cuts don't expire, but it's hard to see how they could keep that in a final bill and still meet the Senate rules."
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7h4n8e | How are multiplayer games programmed? | for example in league of legends it is 5v5 and there are so many different actions and interactions that can happen with each other is it just a bunch of if statements that handle every single situation? | Technology | explainlikeimfive | {
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"There are a number of ways it can be handled. Most often these days, multiplayer games have a \"server-client\" architecture. To put it very simply, the server handles the game logic, and the client renders graphics, plays sounds, sends input commands and tells the server where it thinks you should be. (Which the server may disagree with, hence glitches where you get hit even though it looked like you didn't). Part of the server logic is a thing called an \"event handler.\" Which is *kinda* like a bunch of if statements, in that it is conditional, but it is more dynamic. For a very simple example, let's say a new player joins. An event, maybe called player_join, is triggered. The server sends some info to all the clients, which each run their own code to say \"Dr. Mux joined the game.\" It gets a lot more complicated than that, and I'd go much more in depth if I weren't on my phone at work.",
"There's a central server that acts as the dungeon master. Each player's computer has a network connection to that central server and sends messages like \"I swing my +5 Sword of Smiting at the giant rat\" or \"I cast Magic Missile at player 7\". The server then looks at the strength, armor, hit points, etc. of the target, along with your strength and weapon stats, rolls a virtual D20 (aka random number generator) and sends a message back like \"The rat eats your face\" or \"You just did 30 hit points of damage to player 7\". (Player 7 also gets a similar message.) Your game software then displays the appropriate animation. The server is, basically, a bunch of statements that handle every situation. There's a lot of database lookups involved. So if the server receives the message \"I try to move to position 323,719\", the server executes a function that looks up information from the map to determine if that's a legal move, and if so, how much progress you made. If it receives the message \"I swing the chainsaw at monster 77393\", it looks up your stats, the monster's stats, and makes the appropriate updates. The server has a very very long list of actions you can perform, and statements for each one. As the game evolves, the developers add new actions (do a little dance, make a little love, get down tonight, etc.) and add the code for those actions to the server. Then they issue a game update that includes those actions in the list of things you can do.",
"If you broke down every single computer program out there, basically yes. The programmers create abstractions on top so they're not literally writing every single if statement. But at the hardware level, it is effectively equivalent to billions of if statements. If a user clicks here then figure out what they clicked on. If it was a person do a command to attack. If you are not next to it start moving toward the target. If I need to move update the screen. If this pixel is where the character is change its color to match character."
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7h4p2b | How do the TV commercials about medications for rare diseases make financial sense? | Economics | explainlikeimfive | {
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"dqo51yq"
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"text": [
"Drugs advertised on TV aren’t typically for rare diseases, but for pretty common ones. The drugs are patent protected, so expensive, and the more users the quicker the drug company recoups their R & D spent developing the drug."
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7h4vat | Why does the temperature of a beverage affect it’s flavor so drastically? | Chemistry | explainlikeimfive | {
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"text": [
"The answer is twofold: The first is at lower temperatures, your taste buds become \"numbed\" and have a harder time picking up flavors like sweet and bitterness (this is most apparent when eating frozen foods like ice cream). The second is that flavor compounds are less volatile at lower temperatures, so there's a lot less stuff for your nose to pick up. Since flavor is heavily influenced by smell, the taste will seem very different at lower temperatures."
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7h4vgu | Why does your voice become metallic on Skype/Discord when there are network problems? | Technology | explainlikeimfive | {
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"text": [
"It is not unlike how sometimes an image gets pixelated when the connection gets bad. When sound is digitized, the [sound wave]( URL_1 ) is converted to a list of values that represent its amplitude. The human ear can hear sounds up to 20,000 Hz, so if there are about 40,000 of those values taken each second (known as the *sampling rate*) our ears can't tell the difference between the digital data and the original. More samples require more data, and if the connection cannot stream it all in real time, it will downsample, essential only using ever other sample, or every fourth one, etc. This uses less data, but also makes the wave [less precise]( URL_0 ), losing the higher frequencies, and making the mid-range ones squarer, kind of like autotune.",
"General \"my voice sounds different\" answer: A lot of it has to do with the compression of the audio data coming from your microphone. The human voice only uses a small portion of the audible range, so anything outside of there gets thrown away, and consequently some parts of your voice (overtones mostly). Once this gets sent to the other person and it comes through their speakers, it isn't the same soundwave that was recorded. Specifically when you have network problems: Not all of the data your computer sends gets to the other end, but the program still tries to put it together in the same order it was received. This creates more sharp-looking sound waves when played through a speaker."
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7h5964 | Why is it that freezing things, like an embryo or plant seeds, preserves them where as it would kill other living beings? | Biology | explainlikeimfive | {
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"Someone can correct me if I’m wrong, but from what I understand it has to do with water content and how fast it freezes. As water freezes slowly it creates crystals that can actually rip and tear apart the cells, whereas flash freezing will freeze the water without creating such large crystals. It is easier to flash freeze smaller things as opposed to larger things, such as a person. Again, this is not my area of expertise so someone feel free to explain it better.",
"The basic principle in the freezing of cells (like embryos) is that the freezing stops the proteins and all other stuff from working without disrupting their structure. If the proteins pause functioning, cell division and all other processes pause too, preventing the cell from aging and dying. This is applicable for single cells as all they need for survival is a working replication and protein making system. However, in bigger organisms like humans, the viability of cells is not the only concern for living. Other living beings also need their organs to work for example, which can't just be paused with freezing, basically we have a lot more complicated system than cells."
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7h5kdx | Why are cheap glasses with a positive prescription(ie reading glasses) readily available, but negative prescriptions need to be custom ordered at a much higher cost? | Economics | explainlikeimfive | {
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"text": [
"Prescription reading glasses are not cheap. You have to go through the entire process of having your eyes examined and a specific prescription crafted. This is a medical procedure and fairly highly regulated. \"Reading Glasses\" are not prescription glasses. They are general magnification at set powers that are not specific to the user. The only real difference between them and a magnifying glass is size and you wear it on your face rather than holding it in your hand."
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7h60oa | What is oxidation and reduction? Why do they cause things like changes of color, fire, rust, etc? | Chemistry | explainlikeimfive | {
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"text": [
"Oxidation and reduction can be defined in a few ways, the easiest being that oxidation is gaining oxygen and reduction is losing oxygen. However you can also define it in terms of electrons, hydrogen or oxidation number and I’m sure there are others but I don’t think I’ll need those to answer the question. Basically when things are oxidised you are forming a new compound and that new compound will have different properties. To take the example of rust, you take a metal and now have turned it into an ionic compound which will cause it to have a new structure. The new molecule will have a new colour as different wavelengths of light will be reflected (something to do with how the electrostatic forces affect light, I’m no expert). The fire thing is because many redox reactions reactions are exothermic (give off heat) and if enough heat energy is given off you can get fire. Full disclaimer though, I’m not an expert in any of this so take it with a pinch of salt, I’ll probably be corrected"
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7h6f10 | Why do we sneeze when plucking our eyebrows? | Biology | explainlikeimfive | {
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"text": [
"The nerves for this area are very close to the nerves carrying sensory data from your nose. The signals overlap accidentally."
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7h6rst | How can something exceed 2 Billion Kelvin? | I saw it from [this thread]( URL_0 ) and they were saying it came from a reactor. How can something get that hot and be measured without burning its surroundings? | Physics | explainlikeimfive | {
"a_id": [
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"Something can be really really hot, but not have enough energy to burn something When you use a grinder on metal and the little red sparks fly off, those are crazy hot but they're so small that if they hit your pants they don't have enough energy to burn them despite their high temperature If you bring 1 microgram of stuff up to 2 billion kelvin, then it bumps into a kilogram of the same stuff that is at 500 K then you're going to end up with everything being at just 502 K and nothing exciting happens because there isn't enough energy available to burn the surroundings"
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7h6v00 | what gives bats the ability to hang upside down for extended periods of time without losing consciousness as opposed to humans? | Biology | explainlikeimfive | {
"a_id": [
"dqolvpm",
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"text": [
"Bats have special valves in the blood vessels in their heads to regulate flow against gravity. Humans have never needed that adaptation, so we don't have it.",
"Bats are pretty small. The blood pressure differential between one end of a typical bat and the other is probably about the same as that between the top and bottom of your brain."
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7h7c4b | In a Spongebob episode, Mr. Krabs is shown offering free Krabby Patties. But when all of the customers are in the restaurant, he posts a sign stating that each step they take in his restaurant is priced at $1. Is this legal in the United States, or anywhere in the world? | Other | explainlikeimfive | {
"a_id": [
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"> Is this legal in the United States, or anywhere in the world? No. You can think of such things as informal verbal contracts. If you post up prices for food and then someone comes in and asks to be served one of those items, it is implied that they agreed to pay you the posted price for that item. If they refuse to pay it would be a breach of contract even if they didn't explicitly agree to the terms. A contract however needs to be reasonable and entered into without duress. If for example you advertised artisanal hamburgers and had a fancy menu without any prices, you couldn't turn around and demand they pay you a billion dollars for their meal. The implied contract would be thrown out as unconscionable. But also if you demanded that they pay you for moving as in your example it isn't an agreement they entered into willingly; they cannot help but move even if they intend to reject your contract! So while he could legally lure them in and legally post such a sign he would be unable to enforce such terms on anyone (and might actually be liable for the crime of unlawful imprisonment if someone was confused or ignorant of the law enough to conclude they were trapped).",
"Contracts have to be both reasonable and made in good faith. If I am buying a car from you, and put a bunch of confusing language in so the sale price winds up being $1, that is not a valid contract. Similarly, trying to charge someone for each step they taking in your store would not be legal...it might even be fraud.",
"There is a principle in law where a contract - especially one that a person could enter into unknowingly - must be reasonable. These sorts of things often come up with 'provisions of entry' signs like this one. Krabs customers are entitled to leave, Krabs is entitled to take legal action based on his sign, and the court is entitled to hand Krabs derriere to him on a platter, in the form of court costs."
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7h7dhf | Why do we naturally bend our knees while trying to walk silently? | Hi there, just wondering why do we do this instinctively, and is it even effective? | Biology | explainlikeimfive | {
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"text": [
"When we bend our knees, we get more balance. That added balance gives us more control over our movements, which helps us take quieter steps. Try walking quietly without bending your knees, it's gonna be hard. And even if you pull it off, think of any situation where walking silently and upright would be necessary. There aren't many, it's more of a stalking maneuver. I actually thought about this while I was out hunting today trying to creep up on what I thought was a deer. Slightly related fun fact: humans actually walk very poorly compared to other animals. We kinda just \"fall\" into each step, it's pretty unbalanced compared to other animals."
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7h7e6a | What is the state of matter of a flame? | It’s not solid or liquid, I don’t think flames are a gas... or are they? | Physics | explainlikeimfive | {
"a_id": [
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"text": [
"A flame isn't a state of matter, because it's not matter. It's a *process*, an *activity*. A flame is a chemical reaction where a fuel combines with an oxidizer to produce some sort of new chemical, along with extra heat that causes the reaction to continue. With a typical fire, the fuel can be a solid, liquid, or gas; the oxidizer is gaseous oxygen; and the byproduct is a combination of gas (typically carbon dioxide) and solid particulate matter (soot, which is made up of bits of unburnt carbon). The orange part of the visible flame is cause by bits of soot that are so hot from the reaction that they glow, like metal in a forge. The blue part of the flame is light emitted by the chemical reaction itself."
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7h7fl9 | that feeling the world is moving faster after running on the threadmill for a long time | Biology | explainlikeimfive | {
"a_id": [
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"text": [
"Your brain adjusts to the sensation of constant movement while on the treadmill so that you feel more stable. The side effect of this is that when you suddenly stop your brain is compensating for a condition, the movement, that is no longer present and thus it creates a false impression of instability and loss of equilibrium. Basically the same effect as spinning around in circles and then stopping suddenly which makes the world seem to spin and screws up your balance.",
"When you sense your surroundings, you aren't getting unedited \"footage,\" for lack of a better term. There's a lot of unconscious processing that goes on beforehand. Your brain will sort of tune out things it's being exposed to long term, such as a smell (you won't be able to smell it after a while) or touch (you can't really feel your socks while you're wearing them). The same thing happens with being on a treadmill, where you are walking but your surroundings are not moving. The lack of movement is what your brain tunes out, so when you get off the treadmill, you notice your brain's overcompensation for the feeling of not moving while running."
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7h7fri | If scientists have successfully made antimatter (specifically antihydrogen), and claims that it can “annihilate” a hydrogen atom, how is the Law of Conservation of Matter still valid? | Physics | explainlikeimfive | {
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"text": [
"Conservation of matter isn't a law, conservation of energy is. When the matter and antimatter particles 'annihilate' they are converted into photons that fly out in opposite directions, carrying the total energy (and momentum) that was contained in the two particles. Not a physicist but this is my understanding.",
"It's not. It's an older way of thinking that doesn't take into account mass-energy equivalence (from the famous equation E=mc^(2)). Matter and energy are two sides of the same coin, and what's actually conserved is not matter, but mass-energy.",
"It is not the \"conservation of matter\" it is the \"conservation of energy\". When antimatter meets matter it is converted into nothing but energy. No energy is lost.",
"The main law is conservation of mass-energy. Annihilation will produce photons and particle-antiparticle pairs, and this mass-energy will be conserved so long the total output mass+energy is the same as the initial mass+energy of the hydrogen and antihydrogen atoms. Baryon number is also conserved so far as we know, and this is a type of mass conservation. For normal matter, this is the number of protons plus neutrons. We start with -1 baryon (antihydrogen) add 1 baryon (hydrogen) and finish with 0. See, it's conserved. The same is true for lepton number. It may help to think about how an antihydrogen atom is created. To simplify, you start two energetic particles (and nothing), and crash them together. You wind up these two particles, an antihydrogen atom and a hydrogen (total baryon number -1+1=0, just as you started with), and the amount of non-mass energy is down by twice the mass of a hydrogen atom."
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7h7g3v | What is meditation? | I was reading this comment: post: URL_0 and saw someone comment on what meditation is not. I have also read this: URL_1 but it seems to me people are explaining meditation in a very cryptic sense. In plain basic straightforward non-code blunt english, what is meditation? | Other | explainlikeimfive | {
"a_id": [
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"text": [
"Coming from a Zen Buddhist direction without the mysticism. Meditation is simple but difficult. It is the attempt to directly experience the world without evaluating it. You sit, kneel, whatever. Some sects say you should face a wall, others say you shouldn't, others say it doesn't matter. While sitting you try to stop all the internal chatter your brain goes through. The idea is that the chatter is blocking your view of the way the world is, that you deal more with what your brain is saying than with what reality presents you. When you find yourself in a thought, you acknowledge it and let it go. You don't give it consideration or energy. The thought then goes. This process repeats and eventually your brain settles down and just flows (hard to explain without getting mystical or using mystical-sounding language). Some sects has a monk walking up and down the rows of people with a sort of stick. If you need help focusing and not drifting off, you indicate you want help. The monk will then hit your shoulders with the stick to bring you back to reality. Sometimes they don't wait for your request. It's startlinh, but it helps you come back. Meditation has helped me immensely, especially in terms of dealing with my bipolar disorder. The practice of acknowledge and let go helps me with runaway emotions and thought spirals. Does that help?"
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7h7i7r | Why is the water that comes from a natural spring so cold? | If it's coming from the ground shouldn't it be hot like a geyser? | Other | explainlikeimfive | {
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"Natural springs don't usually run that deep. When you're only a few dozen feet down the ground temperature is just above the average annual temp, which is usually only in the 40s or 50s (F) in the higher latitudes. Geysers are powered by subsurface magma chambers that are much deeper and far hotter."
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7h7jyr | Why is warm tap water murky? | Chemistry | explainlikeimfive | {
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"text": [
"It is not the dissolved oxygen and gases that contribute to tap waters murkiness;gases are basically without colour. Instead, calcium carbonate, which contributes to turbidity, is actually the cause behind warm water's murkiness. It's solubility is inversely related to temperature. As temperature rises, aqueous calcium carbonate takes its solid form and forms a white precipitate which causes a decrease in water clarity, hence warm water's murkiness. edit: And so, when you turn on the hot water, it is not that the water is dirty, it's just the minerals already present in the water in ionic form are taking a solid form.",
"It is caused by dissolved oxygen and other gases that are released when water is heated or depressurized. The milky appearance clears when water is left standing a few minutes"
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7h7kao | The concept of "1 hour on this planet is 7 years on earth" in the movie Insterstellar. | Physics | explainlikeimfive | {
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"It's a concept called time dilation. According to Einstein's theory of relativity, time isn't a constant. Time moves at different speeds. Time moves slower when you are effected by gravity (or moving very fast). The more gravity the slower time flows. So if you were very close to a black hole (as the planet in Interstellar), small bits of time there are the same as large amounts of time elsewhere.",
"Because of Gargantua’s (the black hole the water planet orbits) massive gravitational pull it causes a massive distortion in space-time. This distortion allows for time dilation. Time dilation is a difference in elapsed time measured by two observers either because of velocity or by being differently situated to a gravitational field.",
"All right, so I've always wanted to be a teacher because I LOVE breaking down things and explaining them, so I ask that OP (/u/Deadwalker123) confirm whether or not my following explanation helped you understand the concept. Imagine you're God and you're sitting in a room with with thousands of TV sets hooked up to VCRs. You have 2 identical copies of the film Interstellar on VHS and pop one into a VCR labeled PG (for Planet by Gargantua) and the other into a VCR labeled PS (for Planet by Sun, i.e. Earth). Now assume that these VCRs play at different speeds based on the amount of electrical current you feed into each one. For instance, if you feed in 100 percent of current, the film's runtime will clock at 3 hours (rounded up for convenience). If run the VCR at 50 percent current, the entire movie will appear to play back in slow-motion, and the runtime will be 6 hours, and at 150 percent of current, the film will appear to be playing in fast-forward, and the runtime will be 1.5 hours. Here's where it gets interesting. Say the actors in the film are fully conscious, and to them they're just living their lives. They have no idea how much speed their VHS is being played at because if it is only going at half-speed, *everything* is going half speed from their perspective. People are running at half speed, gravity is working at half speed, their very thought processes are going at half speed because molecules, photons, and electric impulses are going at half speed. Back to our VCRs. PS (planet earth) runs on 100 percent current, and PG runs at 5 percent current. You press play on both PG and PS at the exact same time. In 3 hours the film will have rolled credits on PS but the movie will just be getting started on PG, because PG is running on a fraction of the current. To take the example further, let's assume that you (as god) have each planet running on separate VCRs, and this tape playing back in \"realtime\" and recording rather than simply playing back a film. You invite over two friends, Garry, and Sally, to sample some planets you constructed. Garry hops into PG and Sally hops into PS. You sit down and press play on each and just keep watching. On PS' screen Sally is moving at 100 percent speed exploring town, making friends, dating, getting married having kids, getting old. At the same time, Garry, in PG--which is running on a fraction of the juice, appears to be moving through molasses. In fact, he barely seems to be moving at all. Right before Sally is about to die of old age in PS, you press STOP on both VCRs and have Garry and Sally hop back out into your office (Actually. Garry hops, Sally needs help because her knees are shot and she has arthritis). Sally is all wrinkled and old, and Garrry has barely aged a day. Thing is, their experience of time was the same in that Garry had no idea he was being played back in slow motion. Does that explain it? (If you like and I have more time later, I can try to explain why gravity has this affect on time and our experience it using the same examples)"
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7h88mr | Where does water go during low-tide? | There’s a lot of water on beaches in high-tide but where does this water go once it is low-tide? Does it concentrate elsewhere? | Physics | explainlikeimfive | {
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"Yup, usually towards where ever the moon is. The water gets pulled by the moons gravitational pull and there is actually a little bump (on a planetary scale) where the water is slightly raised by it.",
"As explained, the gravity of the Moon/Sun cause the watery surface of the Earth to become kinda Rugby/American Football shaped. Here's a handy gif. URL_0",
"When it's low tide where you are it's high tide on the other side of the Earth. The gravitational force of the moon pulls the water."
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7h8eak | How will we classify who owns land in space like the moon and other planets? | Other | explainlikeimfive | {
"a_id": [
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"text": [
"At the moment every nation that is capable of space travel has signed onto [The Outer Space Treaty]( URL_0 ) which states that nobody can own any territory in space - it's free to be used by anybody. But it's very easy to agree to that when there's nothing to do in space at the moment except explore and study it. Once somebody figures out a way to make money from it than it'll probably go to whoever has the biggest guns at the time."
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7h8o69 | What is a tensor ? | Mathematics | explainlikeimfive | {
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"how well versed in vectors are you ? Like in algebra, a vector is a representation of an object in a dimensional field. 1 dimension and you have the scalar numbers field. 2 dimensions and you have a planar field. 3 dimensions and you have the space field. etc... etc... Now a point on those fields can be represented by vectors. each dimension is represented by a scalar number. So 1 dimension vector has 1 unique scalar value. 2d has 2, 3d has 3, etc.... Now, you can operate on those vectors. You can translate them, rotate them you can even translate and rotate them at the same time. Like any operations, you have 2 members. The object itself and the amount of change you want to do to it. This is where Tensors fit in. A tensor is basically the parameters ( a matrice that has n(s) dimension ) that would be used to operate on a vector (which represent an object). In Summary, a tensor is a set of parameters to operate on vectors. They are basically just another vector but are called differently because they do not describe an object. They describe the operations to move an object in a dimension."
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7h8pxu | What are voice cracks? | Biology | explainlikeimfive | {
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"Imagine a long thin blanket hanging from a clothesline. When the wind blows it, the entire blanket is pushed by the wind and shakes. That is your normal speaking voice. Imagine this as 100% shaking. Now, imagine a strong, fast gust of wind blows the blanket so that only the bottom half of the blanket shakes. That is your “light voice”, and try to imagine this as 50% shaking. So, the wind is like your breath, and the blankets are like two flaps in your throat. When the flaps change from 100% shaking to 50% shaking, it will sound like a voice cracking. This is my first ever reply to an ELI5. That was challenging, but I hope it worked?",
"Think of your vocal “cords” as a rubber band. They are really folds of ligament, but for our purpose imagine a rubber band. When you pull a rubber band tight, and blow across it, sometimes it will even vibrate and whistle just like your vocal cords do. As you might intuit, the tighter you pull on the rubber band, the higher pitch is produced. Now, there are two sets of muscles that control how tight the vocal “cords” are, and thus what pitch is produced. Think of it like having hooked a finger from each hand through the rubber band - either hand can then control how tight the rubber band is, and they can work together or against each other to make the rubber band as tight or as loose as they want. Also, you should know that one set of muscles (or one hand in our example) is generally used to control deep pitches, and the other is used to control high pitches. That is the eli5 version of how your vocal “cords” work. A voice “cracks” because one of the sets of muscles (usually the deep ones) become fatigued and they “let go” and the other set of muscles (almost always the high pitched ones) take over. This happens most often during puberty in males, because of the way the “Addams Apple” (or thyroid cartilage) changes the shape of a boys throat. In fact it changes which set of muscles (the deep ones or the high ones) are “in charge.” And that is fine - boys go from having high pitched voices to having deep voices. The deep voice muscles should be in charge. The problem, is that the muscles, like any muscle, needs to be used in order to be strong. For the first 12 or so years, the high pitched muscles have been in charge and they are strong and tone and have lots of endurance. But the deep voice muscles are flabby and weak, from not being used. But the deep muscles are suddenly “in charge” because of the new geometry in the Addams Apple. So the deep muscles start out controlling the voice - but then, part way through a sentence they just give out, the high pitched muscles which are still much stronger and have been fighting the deep muscles take over, and the voice slips suddenly and uncontrollably back into high pitch - what we call a crack. Eventually, the deep pitched muscles get stronger just from use, and the high pitched muscles atrophy from disuse and the voice stops cracking - almost forever.",
"Think of your vocal cords like two bumpers on a pinball table that are so close together that the tips touch as they rotate, just for an instant. That rolling kind of motion is how they normally vibrate. The entire length of the vocal cord can be stretched longer though to raise pitch, or bunched up, to lower pitch, which changes the thickness of the two vocal cord edges. Kind of like stretching silly putty makes it thinner. If the shape of the cords and tension on them is such that they can't cleanly create the rolling motion, you end up with harshness and voice cracking. This could also be from swelling such as from over use or irritation."
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7h8r2k | What exactly does radiation poisoning do to our bodies, and how does medicine cure it? | Biology | explainlikeimfive | {
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"It does a lot of things that'll be too difficult to explain in a single post because you need to pull in a lot of information from biology to understand it, but I can try. Ionising radiation is the dangerous kind because it has the power to cause molecules to break up. When a molecule breaks up, it goes from a stable form to an unstable form. This unstable form can attack other molecular bonds, causing damage. The most significant damage in our body from ionising radiation at the beginning is because of Reactive Species (also known as Reactive Oxygen Species but there are other types like Reactive Nitrogen Species or Metals) which are highly reactive and cause a lot of local damage by attacking cellular components that are nearby. When this happens you get one of two things. Either the cell recognises that its too far gone and kills itself (apoptosis). Or, the cell doesn't, and it starts to break apart (necrosis). This is pretty bad. In addition to the cells literally being torn apart (kind of like blending fruits), they also release special molecules (mediators) triggering something called inflammation which can have nasty effects. While it usually helps the body, because your cells are all torn up, you get stuff like bleeding, swelling, fluid in places where you don't usually get it, etc. This is acute radiation damage. You basically give the person an analgesic (painkiller) and hope they survive. We can supply blood and stuff, but the rest of it depends on how strong a person is. The major effects depend on where the cell damage happens. In your bones, you produce less red blood cells, less white blood cells because they normally produce these, so damage = less production. In your intestines, you can cause a lot of bleeding because your intestines have a lot of small vessels to assist absorption of nutrients. On your skin, it starts swelling, bleeding, forming ulcers, and shedding. All of these happen from the same basic principle, its just cells getting shredded and our body trying to help but really messing up and making it worse. The body's also really weakened because of this, and your white blood cell factors can be damaged because of the radiation. We can give antibiotics which help stave off secondary infection while the body tries to heal. And the rest of it: The worse part is DNA mutation. Your cells can usually repair DNA mutation because we have special enzymes that do it. However, this can go wrong. When a gene mutation happens, it can be lethal, causing the cell to kill itself, apoptosis, or stop functioning which also causes it to kill itself. When it's non-lethal, the cell has to catch the mutated gene and repair it. If it can't do it, the cell passes it on. Okay, mutations aren't too bad when you have one. They might have minor effects like the cell not doing the same thing anymore, or they don't recognise other signals that tell it to kill itself, or it might grow really fast, or it might not know when to stop growing. The body can catch cells that do this and kill them, but sometimes they miss them. What's worse, is when they get more than one of these mutations. Suddenly, the cell doesn't respond to other cells telling them to die, and they can hijack cells around them to support themselves (desmoplasia). Even worse, is that they grow fast, they don't know when to stop and that's called cancer. The more of these non-lethal mutations they have, the worse they get, becoming these unrecognisable messes of cells that look nothing like the normal cell and they're very scary because they're like unkillable, super dividing, parasitising super-cells. How do we stop cancer. Well, we could target these cells specifically, but how? They're basically the same as other cells, except they don't really respond properly. One thing we can try is looking for them using X-ray and CTs and such, and finding areas that are strangely dense or lumpy. Then, we use radiation to blast them, hoping that acute radiation damage like I mentioned earlier will kill them before it kills us. Alternatively, we dump a bunch of poison in our body, hoping that those cells die first before our body does. Cancer cells use up more energy and nutrients than other cells do. The hope is that they suck in more poison as well, and that'll kill them first. But this also causes havok on the rest of the body. We don't know how to target them just yet, because each cancer is different. A different gene mutation can give the same cancer in different people, or even in the same cell. I had to shorten a lot because it is _insanely_ complex.",
"There are two types of radiation poisoning, and which is which, affects your options for living. If you are exposed to ionizing radiation, say from an Xray machine, or solar flare, or exposure to hard radiation (without being exposed to the chemicals themselves) then it's like your body got an inside out sun tan. The radiation shoots through your cells like a cosmic machine gun, damaging your DNA, RNA, and basically damaging large amounts of cells at once similar to a flame. The good news is that all a person needs to do is get away from the source of the radiation, and new damage stops immediately. Just like pulling your hand out of a flame stops you from being further burned. The immediate result of this is that the dead or dying cells begin to release toxins into the blood and muscles, the body tissues begin to swell similar to being burned by a fire, and there is trauma to the exposed parts of the body. How much exposure determines how quickly these symptoms set in. Usually from hours to days, although nausea can occur within minutes. The longer term problem is that with the genetic code of your body damaged in so many places, the cells can't reproduce properly, much like a computer program that's been corrupted. This leads to secondary cell deaths, mutations, cancers, and all kinds of nasty secondary effects. If you survive the initial dose of radiation, these secondary effects will plague you the rest of your life. So that is assuming you were exposed to radiation, but not exposed to radioactive elements directly. IE you're exposed to the light, not the light bulb itself. If a person comes in contact with radioactive elements, fallout, nuclear waste, etc, then these sources of radiation get on their skin, in their hair, in their clothes, inhaled in their lungs, ingested in their saliva, and once in the body, they continue releasing that damaging radiation until either they radioactively decay (a very long time), they are cleaned out of the body through something like chelation (not very effective), or the person dies. There are some treatments that can help if administered early enough after exposure. For instance one of the more dangerous elements in nuclear fallout is radioactive iodine, which tends to concentrate in the thyroid. However if you dose somebody up with a large amount of regular iodine, then the thyroid becomes saturated and can't take any more in, effectively rejecting the radioactive iodine. This is the far more dangerous kind of radiation poisoning because you can't remove the person from the source of radiation, since it's inside of their bodies. In other words even if they are moved away from the source of contamination, they themselves are contaminated, and will continue to receive radiation. The paper suits and dust masks that people wear in contaminated areas, do not protect them from radiation at all, but they do provide protection from contamination by radioactive dust by covering their faces and clothing. Now naturally a normal medical xray isn't giving you burns or cancer because it's relatively weak. So we have a measurement system that takes into account actual damage, and risk of damage to your body and we call these Sieverts. It's not a measurement of radiation itself, but is instead a measure of how much damage that radiation would cause to a person. At low levels it increases the risk of cancer. At high levels it results in cell death.",
"Radiation poisoning is basically random damage to cells throughout your body, for more details see [this comment of mine]( URL_0 ). Medicine cannot really cure any of that. It can treat some of the symptoms (like dehydration from vomiting) and prevent those from killing you while your body repairs itself, and it can support some of the body's repair efforts, for example the bone marrow (which is responsible for producing blood cells) can be severely affected, and there is a protein that stimulates bone marrow growth. While it works, blood transfusions can supply the blood cells your body isn't producing. In cases where the radiation poisoning comes from *contamination*, i.e. radioactive material got into your body and is *still* releasing radiation that constantly damages your body, medicine can play a very important role in saving your life by removing some of that radioactive material. For example, giving you lots of non-radioactive iodine can prevent your body from holding onto radioactive iodine, and some substances form bonds with certain radioactive elements and cause your body to excrete them. But if the radiation poisoning is too severe, you will die and the only thing medicine can do is to ease your suffering.",
"If the dose is high enough (~2 Gy), the radiation kill your very sensitive blood stem cells. Your white cell count will diminish and you will have a reduced immune system. If left untreated it's likely to kill you within a few months. If the dose is higher (~4 Gy) your intestines are in danger, and the colon stem cells might die. If this happens your villi in the gut do not regenerate, and are eventually grinded down completely within a few weeks. This leads to open wounds in the colon, and infections, which might kill you, even if you're hospitalized. Your blood stem cells will of course die too, but the gastrointestinal syndrome will kill you first. At super high doses (~ 100 Gy) vessels rupture in the brain and the pressure will kill you within a few days. Little is understood about this case. You are guaranteed to die. So treatment is basically just to keep the body alive and hope that it manages to regenerate new stem cells e.g. through transplants. And these are all the syndromes associated with a whole-body dose. For medical radiation cases, the dose is localized. In that case a too high dose will cause the skin to die (necrosis) which if left untreated will lead to nasty infections and death. Skin grafts have been used to save patients whose been accidentally over-exposed.",
"Radiation cause mutations in our DNA. Basically, it's because they are high-energy photons and colliding with the DNA molecule they give this energy to the atomic bonds, breaking them or changing them. So maybe a base will be missing or it will be changed. This mutation leads to diseases such as tumors, or (if it affects gonads) it will show in children (and this is why radiation is dangerous not only for an individual, but also for their descendants). The mutation itself can't be cured, unless you modify the DNA (but it isn't a realistic possibility): you can only cure the results of that mutation."
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7h8r7y | Why do car manufacturers have to sell thought dealers? Why are they not allowed to sell direct to the consumer? | Economics | explainlikeimfive | {
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"URL_0 In short: decades ago car dealership associations convinced law makers to make laws requiring car to be sold through car dealership only."
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7h8t8j | What are the underlying molecular mechanisms behind when we exercise and our body gets warm? | Biology | explainlikeimfive | {
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"I'm not really 100% sure what your question is asking but I'll take a stab at it. Skeletal muscle, which makes up all of the muscles that you can voluntarily move, when contracting (pulling inwards) uses a lot of this molecule called Adenosine Triphosphate. It's a small molecule called adenosine which has 3 phosphate molecules attached to it. That doesn't really matter - the thing that does is that when 2 of these break off, the bond releases a lot of energy. Some of this energy goes to power the muscle (myosin heads) causing muscle fibres to pull together. However, some of this energy is released into the surroundings. If you have too much heat in one place, you can hurt your cells causing them to suicide. The heat is moved out of the body by the blood. Your body has this automatic mechanism called the sympathetic nervous system that makes up the \"fight or flight response.\" To do this, it has special nerve fibres that release two chemicals: noradrenaline directly at certain sites, and adrenaline into the blood (through the adrenal gland above your kidney). These act at the innermost layer of blood vessels, particularly arteries called the endothelium. Their action stimulates the release of a molecule called Nitrous Oxide (NO). It moves into the smooth muscle layer (just outside the endothelium) where it causes them to relax. This causes the blood vessels to dilatate which is just a fancy term for they get wider. It also acts at your heart through special fibres called Purkinje Fibres and also at a special place called the Sinoatrial Node. This causes your heart to beat faster and harder. The big effect from all of this is that your blood moves faster and more of it moves around you body (iirc it can go up to 20x more volume per minute), and blood moves from deepest parts to the outermost parts, then back into the deepest parts. Blood that moves through the skeletal muscle is faster, carrying heat away from your muscle towards your skin, where you radiate it outwards from your body. Your body heats up, and you get warmer because of it."
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7h90iw | What determines the neutron cross section of an atom? Why does Zirconium have such a small one? | As I understand it, the neutron cross section of an element is the approximate surface area with which a stray neutron can collide. I can't see how this is altered by anything else than the size of the nucleus, as the bigger the nucleus, the more nucleus there is to hit, right? However that is not true. The neutron cross sections of various elements are graphed here: URL_0 As can be seen, there seems to be little correlation between neutron cross section and atomic number (and therefore nucleus size) So why do some elements, such as oxygen, have such a small neutron cross section? What forces are at work here? I don't think it can be electric charge because neutrons are neutral. Also I've read that they use Zirconium (n=40) (b=0.184) in nuclear fuel rods because it has such a small neutron cross-section... but other solids such as Silicon (b=0.166), Lead (b=0.171), and Bismuth (B=0.034) are significantly lower, yet are not used. Is this because alloyed Zirconium is a better compromise with structural strength? Thanks in advance! | Physics | explainlikeimfive | {
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"... I, personally, can't wait to see how other users would choose to explain advanced particle physics to a kindergartener.",
"> As I understand it, the neutron cross section of an element is the approximate surface area with which a stray neutron can collide. Yes, although it's very dangerous to take the analogy with a geometric cross-sectional area too far. For example if you look at thermal neutron-induced fission cross sections on fissile nuclides, and try to interpret them geometrically, you'd erroneously conclude that the fissile nucleus is **much** larger than it actually is. You should't think of a cross section as a \"size\" of the target nucleus, but rather as a probability of some process occurring. > So why do some elements, such as oxygen, have such a small neutron cross section? What forces are at work here? I don't think it can be electric charge because neutrons are neutral. The cross sections depend a lot on the energy of the neutron, and on the structure of the target nucleus. For example if you have oxygen-16, it's already a [doubly-magic]( URL_0 ) nucleus, and it doesn't really want to capture any additional nucleons."
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7h9268 | Wood is basically carbon that plants get thru respiration and what about us? What are the basic material that form us and how do we get it from, air, food? | Biology | explainlikeimfive | {
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"Our skeletons are mainly calcium. The rest of us (if you don't count all the water in our bodies) is primarily carbon, just like plants. And we get that carbon from our food. As you said, plants are carbon, and so is meat, so what we eat is primarily carbon."
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7h95j0 | What is it exactly that is keeping us from "curing" cancer and other currently incurable illnesses? | Biology | explainlikeimfive | {
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"\"Cancer\" isn't one specific illness. Instead, it refers to a group of illnesses caused by abnormal cell growth. There are a HUGE number of different cell types in the body, all of which have their own specific machinery, which allows them to do their job. So for example, an abnormal white blood cell will be completely different than an abnormal liver cell. To make things more complicated, there are many different causes for a cell to turn cancerous. In order to \"cure\" \"cancer\" we would need to have every bit of cellular machinery of every different type of cell figured out. We would then need to have different medications that target each of these specific cells ideally without causing too much collateral damage.",
"Cancer cells are so similar to the good cells in our body we haven’t found a better way to target the cells with that tiny slice of malicious DNA and exterminate them. The best we’ve come up with is going in a slicing the tumor out manually or blasting it with radiation, but it gets tricky when the cancer cells form inside of complex organs like your liver or brain. Since we haven’t found a drug that can consistently target and kill the cancer cells, cancer remains generally uncured.",
"There are so many pathways involved in the generation/progression of cancer cells. Plus, it’s different for different types of cancers. Sometimes a key, critical pathway is found that when targeted, can blast all/most of the cancer cells. Most of the time though, blocking one pathway isn’t adequate because there are others involved (which may or may not be known/discovered)."
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7h96s2 | Do animals understand when humans help them? If so, why? | Biology | explainlikeimfive | {
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"The most honest answer is that nobody knows for sure: and unless mind-reading devices are even possible to invent, we never will know for sure. Certainly, some individual animals do act as if they know that humans can help them, even appearing to seek humans out for help. Whether they have some idea that humans are clever and generally well-meaning, we can't possibly know, although that might be the case with domestic pets (particularly dogs and cats) and very intelligent species (like elephants). Or maybe if they're in a hopeless situation, they feel they have nothing to lose. Why do they not hang around after they've been saved? Well, why should they? They probably don't have a concept of \"thanks\"; they probably do just want to get away from a place where a nasty thing happened to them.",
"They sometimes can and do. It very much depends on a combination of the state of the animal, the conditions under which it was raised, its personality, what it's observing, and its intelligence level. Whether or not its instincts are in conflict can also impact its response. There's lots of examples of animals that override their 'flee' instinct when they're confronted with one of their babies being in trouble. There's youtube videos of ducks calling for humans to help get their trapped ducklings out of some situation. Perhaps it was a 'park duck' that was used to humans and saw them as only mildly threatening. Then there's a few neat stories of penguins and condors who \"come home\" to greet the humans that previously helped raise or rescue them have hit Reddit in recent times. Those situations might be awareness and something like gratitude, or it might be a result of imprinting or some mildly twisted form of pair-bonding. Intelligence and the ability to process cause-and-effect are probably key elements if that's not the case. But there's also lots of other examples where well-meaning humans get injured or killed attempting to help. We recently lost a \"whale rescuer\" who was killed after releasing a whale from its entangling fishing-gear, when it should have been pretty clear that he was trying to help."
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7h99al | why cold hands and feet feel like they are burning when you run water over them? | Biology | explainlikeimfive | {
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"The transfer of heat is what causes you to feel like your hands are burning. It works both ways though. If you put your hands in boiling water, they'll burn because your hands are much colder than the water, so the amount of heat energy transferred between them is enormous, causing the burning sensation. The same is true for extremely cold environments. If you put your hands in dry ice, it'll burn because your hands are so much warmer, and a massive amount of heat energy is transferring from your hands to the ice."
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7h9aaj | Why does your body feel warm from drinking alcohol? | . | Biology | explainlikeimfive | {
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"text": [
"Alcohol dilates your blood vessels. This brings you blood (which is at inner body temperature) closer to your skin (which has a lower temperature), warming it. This also has the added effect of actually lowering your body temperature."
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7h9bav | Why do our voices sound different on video, than we hear them? | Biology | explainlikeimfive | {
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"text": [
"Your vocal chords are internal to your body. This means that the vibration not only propagate thru your mouth opening but also thru your own body. This means that not only you are hearing yourself but are also \"feeling\" your voice from the inside. Listening to a external device that reproduce your own voice is different because you are not experiencing those vibrations internally and your brain is trained to detect that difference."
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7h9ldh | Why isn’t there more competition between the pseudo-monopoly ISPs? | Other | explainlikeimfive | {
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"text": [
"It costs hundreds of millions of dollars to set up all the infrastructure in a mid/large city. The existing cable companies generally built out with tax breaks, subsidies & the like and have slowly upgraded their equipment over the years, so it was never a massive financial hit all at once. For any new company to break into the market, they'd have to pay it all up-front and look at it taking years, if not decades, to recoup the investment. ...all while trying to compete against an entrenched near-monopoly that can easily afford to cut their rates in places the startup is trying to compete until the startup goes bankrupt. Cable companies, like electrical companies, are what we tend to call \"natural monopolies\". The barrier to entry into the industry is so large that it doesn't make sense to try competing. We'd have similar situations with phones if it wasn't for regulation drawn up dealing with AT & T's monopoly."
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7h9mp8 | How does graphite stay on paper? | Chemistry | explainlikeimfive | {
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"text": [
"Graphite is relatively soft, and as you scrape it along a surface, tiny bits of it crumble away and stay behind. These bits are insaaanely individually tiny and make up an extremely fine powder. Paper is not as smooth as you might think. It's covered in ridges and pores and little valleys. So as you are dragging the graphite along a piece of paper and leaving the trail of ultra fine powder behind it, you're also applying a bit of pressure between the pencil tip and the paper, effectively packing the graphite dust into all those grooves and pores and ridges in the paper. Erasers work because they're soft and also extremely porous, wich allows them to sink into the textures along the surface of the paper and collect that graphite dust up in it's own surface, taking it from the paper. As you can imagine this process doesn't work perfectly every swipe, which is why erasers sometimes leave smudges behind."
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7ha175 | How do Scientists know whether or not s dinosaur was herbivore, carnivore, or omnivaur? | What about their skeletons / bones gives it away? | Biology | explainlikeimfive | {
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"text": [
"Their teeth mostly. Herbivores and carnivores have very different sets of teeth, for different purpose (crushing leaves, tearing flesh...)",
"We can compare them to what we know about modern today since skeletal structures haven't changed that much between dinosaurs and vertebrate modern life. Crocodiles and alligators are a good example since they're a very ancient species, who's direct ancestors first started taking on their modern form around the Jurassic period. They have long pointed teeth for tearing at flesh, and we know they're meat eaters, so it can be assumed that dinosaurs, also reptiles, with long pointy teeth were also meat eaters. An animal with flat teeth for grinding, like a tortoise, uses its teeth to chew up dense plant matter. So dinosaurs with flat teeth are also likely doing the same. Animals with both kinds of teeth, like humans, likely are eating both meat and plants."
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7ha954 | What exactly is the advantage of smartphones having all glass bodies? Is there a reason companies have been making the backs of their phones glass too? | Technology | explainlikeimfive | {
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"text": [
"They look really pretty in product shots. Makes them look & feel \"luxurious\" even though glass is of course cheap as dirt, but plastic *feels* cheaper."
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7hafms | How do smells 'disappear'? Why hours after I go to the bathroom, even if the windows are closed and there's no ventilation system in the room, the bad smell seems to have faded away? Where do the 'smelling' particles go? | Biology | explainlikeimfive | {
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"text": [
"Heavier particles settle and eventually sink to the floor or stick to walls. Lighter gasses will disperse since home construction is not airtight. Also, your own sense of smell gets used to scents fairly quickly, when a smell is no longer \"new\" your nose doesn't bother to tell you the smell is still there.",
"Just because you don’t see an escape for gases does mean one doesn’t exist, the creep through the tiniest of places like under a door. And also, they spread out really uniformly throughout the bathroom. Even if it’s a small bathroom, a uniform distribution would greatly reduce our ability to smell them, and then they start leaking out small cracks and crevices"
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7hag2w | How does a fridge work? | Technology | explainlikeimfive | {
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"HVAC guy here: Refrigerators work by TRANSFERRING heat from one location (inside the fridge) to another (outside the fridge). This is done using a chemical compound called REFRIGERANT (Like R-134). Refrigerant is a liquid that boils a a low temperature (R-134 boils at -15deg~F/-26deg~C) Essentially the refrigerant \"boils\" (absorbing heat inside the fridge) and then is pumped back towards the outside of the fridge where it \"sheds\" that heat. The process repeats continually using an electric pump (condenser) and fan as needed.",
"In thermodynamics they love cycles, usually in 4 steps. The one that applies for this process is the [reverse Carnot cycle]( URL_0 ). We start our cycle in point D: * D - > C is an isotherm expansion. As u/apatheticviews said: this is accomplished by using a liquid that boils at a low temperature. Boiling happens at a constant temperature (= isotherm) and expands a liquid into a gas (= expanson), and absorbs heat from the fridge. * C - > B is an adiabatic compression. The pressure increases (=compression), without exchanging heat to the environment (=adiabatic). This causes the temperature to rise. This step requires a lot of energy! * B - > A is the reverse of step 1, but this time on a higher temperature (above room temperature) so that it can transfer heat to your room. The heat has now succesfully be transfered from your cool fridge, to your hot room. * A - > D is the reverse of step 2, and recovers some of the energy you used in step 2. As with all thermodynamic processes: full reversal is not possible. The energy that isn't recoverable is the energy you will need to provide as electricity from the wall. Additional note: This energy you add as electricity also gets dissipated as heat to your room, as shown in the left diagram on the picture. Therefore, using your fridge to cool your room is counterproductive: all heat you extract is dumped in the room anyway + all electricity consumed in that process is also dumped as heat = > You'll only heat up your room even more.",
"Don't even ask me what internet hole I fell into this morning, but what are the odds that I ended up watching this 1963 US Air Force training video about the principals of refrigeration??? It seems fate wanted me to share it here today. URL_0",
"You see, matter is a bit claustrophobic. If you reduce the volume some matter has to its disposition, it gets agitated and heats up. Similarly, if you increase the room the same matter has, it becomes less agitated and cools down. A fridge or freezer works by transferring heat from inside the fridge to the outside room. It does this by circulating a fluid (the refridgerant) which absorb the heat on the inside, and release it on the outside. The way this works is by manipulating the state of the refrigerant with a low boiling point (around -15 degrees Celcius) from gas to liquid. The refridgerant starts in a liquid state and is pumped into the fridges walls & doors. There it absorbs heat from the air inside the fridge, which makes it boil making it go from liquid to gaseous form. Note that you can have matter at two states even if the temperature is the same! This is because instead of using the added energy to heat the matter up, you use it to convert it to gas. Thus the refridgerant is now at a gas state. The refridgerant is now run through a pump which increases pressure. This is the noise you hear when the fridge is running. Now since the pump to forces more gas into the same volume, the gas heats up. The gas is then fed through the condensator, the typical tubes/grills you see at the back of your fridge. The tube here has a wider diameter than before, which makes the gas less agitated, and thus it releases enough energy to condense into liquid again. The heat is therefore released to the surroundings. From here the cycle repeats and the now cooled liquid is pumped back into the fridge walls to transfer more heat. This is also how a heat pump works, just in reverse! tl;dr the fridge transports heat from inside the fridge to the outside by evaporating and condensing gas."
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7hagns | Why does our vision sometimes go distorted when we stand up to fast? The blur effect... | Biology | explainlikeimfive | {
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"When we get out of bed or stand up, the blood vessels in our body need to clamp down rapidly to maintain blood pressure going to the brain. If we stand too quickly, blood pressure can drop and cause dizziness, light-headedness or fuzzy vision. This may just be a symptom of getting up too quickly, so it's important when getting out of bed in the morning to do so slowly. If your blood pressure drops abnormally when sitting or standing then you could have \"orthostatic hypotension.\" This typically lasts for minutes, not just a second. Causes of orthostatic hypotension include age, medications -- especially blood pressure medications -- and disease of the nervous system."
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7hakxb | If pictures are stored as a bunch of numbers, why can't you just create random new pictures by changing some of the numbers? | Technology | explainlikeimfive | {
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"dqpf4w3"
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"text": [
"You can do that, but if you try to create a picture from completely random pixels, then in most cases (as in 99.9999999999999999999999999% of the times) you'll get [white noise]( URL_0 ) (well you'll get it in color, but it's the same idea). You need to have some algorithm that will make your image make some sense."
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7hasqw | Why does every muscle is our body need rest after a short period of exertion, yet our heart can pump rigorously for 80-100 years straight? | Biology | explainlikeimfive | {
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"text": [
"Muscles are active when they get a signal via Nervs (or electric shocks ⚡️). These Neurons are connected to the 🧠. The heart however has it own Neuronsystem which are actually not even Neurons but specialised muscle fibres. Technically a heart could beat outside of the body because it can shock itself. So when you are brain dead your heart still beats. Neurons are bound to something which prevents them do get shocked to much on the other hand. We call it refractary time. While the heart muscle does that too (beating and pumping depends on that) the „heart brain“ does not need to have that rest time since it is shocked very differently"
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7hb1xw | What are the benefits to holding votes in the middle of the night? | Other | explainlikeimfive | {
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"I assume you're talking about the US congress, but also it's a concern for corporate boards, nonprofits, and other collaborative bodies. Two reasons: one benign, and one not. The benign one is that sometimes you just want to get the thing done. Everyone has been talking about it for 13 hours, it's now the middle of the night, there's still that dude who keeps bringing up random stuff, and you still have a dozen things you need to do before you can go home. So you hold a vote, and settle the issue. The not-benign reason is to hide what you're doing. You know it's going to be unpopular, you've gathered the votes you need beforehand, and hope that no one will notice. This isn't necessarily bad -- sometimes unpopular decisions need to be made, and it's only human to want to avoid being attacked afterward. More often, and especially in the US congress, it's to make sure the news cycle finds some other shiny object overnight (\"hey everyone, here's a dachshund that can dance!\") before anyone notices."
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7hbbow | Why has natural selection not removed people with nut allergies, lactose intolerant and so on? | Biology | explainlikeimfive | {
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"text": [
"Mammals in general are lactose intolerate; they only need to drink milk as infants, once they're done being weaned, they typically stop being able to tolerate lactose. Most humans are lactose intolerant, and becoming able to eat lactose as an adult is a relatively NEW adaptation, mostly present in groups in northern latitudes where milk was an important resource. Allergies are an effect on an over active immune system, responding to a harmless allergen as if it were a dangerous allergen. If your immune system was *weak* you'd be dead, so our strong immune system is the end result of a long history of selection for a *stronger* immune system. People who die of a peanut allergy are basically a glitch, but their deaths are insufficient to impact population growth."
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7hbm7j | What is a Fractional Reserve? | Explain with an example? | Economics | explainlikeimfive | {
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"> What is a Fractional Reserve? A bank takes in deposits, then turns around and loans some of that money to other people for profit. The fractional reserve is the fraction of deposits the bank is required to keep on hand for if people want to withdraw their money. For example a bank might take in $100 million in deposits and loan out $70 million to collect interest. They are required to keep 30% of the deposits on hand so that some people can take their money out when they want, and that is the \"fractional reserve\"."
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7hccnn | In movies, ads, photos, etc. doctors are wearing a headband with a silver/chrome circle. What is that and what is it’s use? | Other | explainlikeimfive | {
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"text": [
"It's a [head mirror]( URL_0 ). It was used back before small handheld electric lights existed. It's a concave mirror with a small hole in the middle. The doctor places it in front of their eye, and looks through the hole. They then line the patient up with a light source behind them. The mirror then projects a ring of light toward the patient without the doctor's head getting in the way, allowing them to examine the ears, nose, and throat. It's obsolete these days, but it was common for so long that it's become sort of a \"symbol\" of doctors."
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7hcwz7 | Why does listening to music while doing chores or generally unenjoyable things make them bearable, or sometimes even entertaining? | Biology | explainlikeimfive | {
"a_id": [
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"text": [
"Because your taking something horrible but adding something you like to trick your brain into thinking it’s not that bad... it’s more of a distraction cuz once you remove the music... the chore is just as dull and boring as always",
"You’re distracting your mind while you do a mundane task. You may get similar results by listening to podcasts or audiobooks."
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7hdk50 | Why are 9mm bullets less dangerous than 7.62 or even 5.56 ones? Shouldn’t they deal more damage with bigger size? | Physics | explainlikeimfive | {
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"9mm bullets are dangerous. However they are a handgun round. They're less aerodynamic and have less power coming out of the barrel. They're not designed for long-distance flight. 7.62/.308 and 5.56/.223 are rifle rounds. They have more power out the barrel and are designed for long- distance, accurate engagement.",
"I think the ELI5 would be that the size of the gunpowder charge behind the bullet is what makes the difference. I could take any of those bullets you listed and throw it at you, and it's not gonna do much damage. Rifle rounds have a much bigger gunpowder charge behind them, which makes a bigger boom, which moves the bullet faster, and a faster bullet has more energy to transfer to soft bodily tissues. A lot more still comes into play though, like what material the bullet is made from, how far the bullet travels, and where you are hit.",
"Diameter of the bullet isn't the only dimension that matters. The 9mm bullet is larger in diameter than the two rifle rounds, but has significantly less energy behind it and is lighter than the 7.62 bullet. The rifle rounds have a lot more gun powder packed behind them so they leave at much greater speed and can deliver a lot more energy to the target. [Look at an image of the various rounds]( URL_0 ), the two on the left have the largest diameter, but the two on the right have a lot more *Boom* behind them to get them to the target. The far right round is the 7.62 that AKs use, the NATO 7.62 is significantly longer",
"Strictly speaking, a 9mm bullet (~8 grams) has more energy than a 5.56mm bullet (~4 grams) and will therefore do more damage *if they are moving at the same velocity.* That last part is a big caveat. If you just look at the two cartridges, you'll see that a 5.56 rifle round has much more propellant than a 9mm pistol cartridge. Also, a rifle's barrel is longer which means the bullet has a longer distance over which to accelerate. What matters is the mass of the bullet *and* the velocity at which it flies. Gun types express this as \"muzzle energy\" which is 1/2mv^(2) (m being the bullet mass and v being the velocity as it leaves the barrel.) Depending on the gun, a 9mm bullet has around 600 joules of muzzle energy, where a 5.56mm has around 1800 joules. This is a closer analogue of what kind of \"damage\" the round does but that also depends a lot on the target.",
"Why are basketballs less dangerous than baseballs? Shouldn’t they deal more damage with bigger size? Baseballs move a whole lot faster than basketballs, typically. And despite being smaller, they are heavier for their size. It’s like that with bullets. Rifle bullets aren’t as wide, but they’re longer and they’re moving faster."
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7hdmy8 | What is the role of Gaddafi's death in todays slavery in Libya? | Other | explainlikeimfive | {
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"text": [
"Removing the regulatory body allows illegal activites to operate in the open. The slavery industry always existed but without a practical government they can operate in the open now.",
"It wasn't so much the death of Gaddafi as it was the failure to form a stable government to replace his rule. This idea that you can remove a dictator and \"the people\" will replace him with a democracy seems to have been one of the USA's ideological blind spots in recent decades. You got better results when doing the opposite: replacing democratic governments with dictators, as in Iran, Guatemala, and Chile."
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7hdypn | What makes a fluid either compressible or non-compressible? | What is it about liquids such a water to be non-compressible while others can be compressed? | Physics | explainlikeimfive | {
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"Can't wait to hear this discussed. I was an electrician on aircraft in the Air Force, and we often ventured into some components where we overlapped with the hydraulic mechanics. I've heard numerous times that water isn't compressible, so wouldn't make a good hydraulic fluid on aircraft, while the red petroleum based fluid we used did. I never could wrap my brain around that.",
"Gases are compressible because the molecules have a lot of empty space in between. If you push on a molecule, it has a lot of empty space to move into. So it is easy to compress the gas. In a liquid, the molecules are almost touching. (Molecules don't really have well-enough-defined boundaries to \"touch\", but it's OK to think of them that way to a first approximation.) There is a little bit of space, but not much. So when you push on one water molecule, the neighboring molecules push back on it, and their neighbors push back on them, and so on, making liquid water much harder to compress than a gas."
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7hdztc | Can we scale lasers up indefinitely with the only issue being enough power and/or money? Can we in theory make a deathstar laser if we just had enough of our current resources? | Physics | explainlikeimfive | {
"a_id": [
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"text": [
"Basically yes. There is also the issue of hardware capable of handling that power, because it would just catch fire. But theoretically yes",
"Scaling them up is hard, you start having too much heat and not enough surface area, but you can always have a lot of them and focus them on a single point like they did with the [Shiva laser]( URL_1 ). One of its successors [HiPER]( URL_0 ) can put out a 4 PW pulse. That is 4x10^18 times stronger than your standard laser pointer, but just for 10 picoseconds We'll blow up Alderaan someday!"
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7he506 | Is there a reason why birds kamikaze into my window? | Other | explainlikeimfive | {
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"text": [
"When this happens it is either the bird thinking your clean window is open air and they fly into it trying to fly into your home, or they see their reflection in the window and think it is a rival bird entering their territory and they try to attack it."
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7he5h1 | How do the foam cutouts in a recording studio mute out sound? | Physics | explainlikeimfive | {
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"text": [
"They don't mute the sound they absorb it. Picture this: throw a golf ball as hard as you can into a tiny room with concrete walls, floor, and ceiling. What did that golf ball do? Now cover the walls, floor, and ceiling with thick feather pillows and throw that golf ball. The golf ball represents the sound travel.",
"sound waves are just vibrations at different frequencies, a dense material like foam absorbs those vibrations more effectively that a harder surface like concrete, thus reducing reverb..",
"They both absorb the energy of the sound wave as well as breaking up the reflecting echos in to multiple interference patterns. They use these for testing electronics as well URL_0"
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7hef4i | what is the chemistry of photography? | So I'm taking an intro to photography class which has us in a lab developing film and photos. I'm just curious as to what the chemicals are doing and how we end up with a photo. | Chemistry | explainlikeimfive | {
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"URL_0 (Black-and-white) film is basically plastic with a mixture of silver halides and gelatin spread on it. When you expose the film (ie, when you point the camera at something and push the button), where the light hits the silver halide, a tiny amount of it is turned into elemental silver. It basically creates a bunch of extremely tiny pockets of elemental silver. These pockets can be as small as single digits of atoms. In the developing can, first, you add a *developer,* a chemical which, when it runs into a particle of elemental silver, converts nearby silver halides into more elemental silver. It grows those tiny pockets of elemental silver into crystals. The crystals are maybe a hundred billion times bigger than the original pockets- a few thousand times bigger in each dimension. Their exact size (which determines how dark your negative will be) depends on how long the film sits in the developer. So when you determine that it's been long enough, you pour out the developer and add a stop bath. This is just a weak acid that neutralizes any developer that's on the film. And you dump out the stop bath, so it both neutralizes the developer and physically washes it out. Last, you pour in a chemical that dissolves the remaining, unconverted silver halides. Otherwise, when you looked at the developed film in light, it would darken (very gradually, because it's not being boosted by developer chemicals.) Then you basically just wash and dry the film, and you've got negatives."
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7hefgg | Why don’t we freeze at night? | If the diameter of earth is around 8,000 miles or around 12,750km, wouldn’t we be 8,000 miles further from the sun at night and isn’t the reason that it’s colder in the winter because that hemisphere is pointed away from the sun. I heard once that the earth stores heat or something but clarification would be nice. thanks. | Other | explainlikeimfive | {
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"> wouldn’t we be 8,000 miles further from the sun at night More or less. > and isn’t the reason that it’s colder in the winter because that hemisphere is pointed away from the sun It's colder in winter because of the change in the angle of sunlight. Seasons have nothing to do with the distance to the sun. The Earth is over a million miles *closer* the sun in the winter (in the Northern hemisphere) than in the summer. It's just colder because the sunlight is hitting at more of an angle, which means that there's less light energy per square meter. > I heard once that the earth stores heat or something Yep. If one side of the Earth *always* pointed away from the sun, the temperature would drop more and more until it was incredibly cold. But the ground and water absorb heat during the day, and radiate it back out at night, keeping temperatures more even.",
"When you take a pot off the stove does it become instantly cool? No. Because it has absorbed some of the heat and must slowly release it back to the environment as it cools. Everything around you is the same. The Earth, the air, your house, etc. It's all absorbing heat from the sun all day. And a huge quantity of air or the tremendous mass of the Earth doesn't cool down quickly."
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7hegc5 | How does the police force work in the UK? | Other | explainlikeimfive | {
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"The armed branches of the police are specialised units. The average police officer in the UK does not need guns as the criminals for the most part do not have guns nor do the public. Every police force has way more armed officers than most people would think, and many of them are plain clothes officers in supercharged but normal looking cars. If an unarmed police officer suspects that an armed officer is needed they will let their superiors know and armed officers will be quietly moved nearby.",
"Most beat/patrol cops do not carry firearms; they usually carry a baton, handcuffs, and a canister of CS spray (sort of like pepper spray). Incidents which require a better-armed force will have [armed response vehicles]( URL_1 ) called in, which can carry anything from pistols to carbines, along with other specialized equipment (one of the pictures on that page shows an ARV with riot gear in the trunk). ARVs are usually staffed by 2-3 firearms-trained officers. This varies from police force to police force. This \"works\" because the population is similarly \"disarmed\". The most common armed threat to a patrolman is a knife, leading to [stab (proof) vests]( URL_0 ) becoming standard issue.",
"In addition to the other comments, the Police have got reasonably good at predicting where armed units are likely to be needed and keeping response times quite low. In a small village where the major crime problem is an excess of crusty jugglers, the nearest armed unit will be a long long way away, and probably asleep, whereas London has a number of armed response units permanently available and patrolling."
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7heiv0 | How do sodium-acetate heat pads work? | Chemistry | explainlikeimfive | {
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"text": [
"Sodium acetate is an unstable solution at room temperature. When you heat crystalline sodium acetate, it becomes a liquid, and will stay that way as it cools, so long as it's not \"jostled\". If it is in the presence of what is call a nucleation site (bubbles, dust, some tiny disturbance), the liquid sodium acetate converts back into crystal. This state change is exothermic, meaning it gives off heat. The hand warmers have little metal buttons in them. When you click the button, it creates little bubbles that cause the state change to start. Heating them adds the energy needed to start the process all over again."
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7hepqf | credit cards vs debit cards | Economics | explainlikeimfive | {
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"With a credit card the bank pays the business you use it at, then sends you one bill per month for that months spending. With a debit card it is linked to your checking account and the money is moved from your account to the stores.",
"Credit cards are a loan that the bank gives you at the time of purchase which you have to pay back later. Debit cards just take money straight from your account. A credit card will be declined if the bank isn't willing you loan you any more money. A debit card will be declined when you don't have enough money in your account to cover the purchase. Credit cards generally have rewards associated with them, often things like 1-3% cash back or airline miles. This is to encourage you to use those cards, thereby running up a balance and likely paying interest on it. Debit cards seldom if every offer rewards. Credit cards generally offer pretty comprehensive fraud resolution services--you can call up your credit card issuer and state that you received an item that was not as described by the merchant and 9 times out of 10 they'll refund the money to you. You also generally have much less liability if a credit card gets stolen; your liability is generally limited by law for credit cards, while debit cards will vary from card to card. For a perfectly organized, perfectly responsible individual, credit cards are superior. For someone who can be tempted by the illusion of \"free money\" that credit cards offer it can be safer to stick with debit; debit cards generally can't put you in debt.",
"Credit cards are (functionally) short term loans. Rather than paying with money out of your account, the bank that issued the card is extending you a loan. If you pay it off one the first billing cycle (30 days) they do not charge you any interest, but after that first cycle they charge you interest on the balance of the card. Debit cards by contrast pull money directly from your bank account. A little bit safer because they don't build a balance that carries interest, but it also means that if your balance is zero your card is useless.",
"A debit card immediately takes the funds out of your account to pay for what you're buying. If there isn't enough in your account it will be declined, or your account will get overdrawn. A credit card subtracts the payment from your credit limit. At the end of the billing period (usually monthly) you can either pay off all the charges you've made against your credit limit, or pay an interest fee and continue with those charges on the card. With a credit card you can spend more money than you have, but you must continue to pay the interest fees on what you've spent until you pay it all off."
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7het6b | G forces | ELI5: Im curious as to how fighter pilots train to deal with high G Forces? How long would it take to be able to deal with them? Are some people naturally more able to deal with them? What do pilots do during high g force manoeuvres that prevent them from fainting? | Physics | explainlikeimfive | {
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"> Im curious as to how fighter pilots train to deal with high G Forces? By training. No, really it's actually that simple. Sustaining g-forces is a cumulative process. Muscle strength -- and specifically which to apply during what sort of maneuver; strength training and conditioning is the daily regime. > How long would it take to be able to deal with them? It's immediate - next time you're driving fast around a corner, clench you abdominal's and keep your head upright. Your learning and getting better. > Are some people naturally more able to deal with them? I don't think so, you'll have to wait for someone with more first hand experience to chime in. Body structure obviously plays an innate role and imposes a maximum, but it's not a prerequisite. > What do pilots do during high g force manoeuvres that prevent them from fainting? As mentioned, muscles. In combination with suits containing dynamically pressurized compartments to assist in controlling the flow of blood. Other techniques are used such as breath exhalation and such, but that's in the upper regimes."
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7hezg4 | Why is astronaut Scott Kelly’s body suffering severe health issues after 300+ days in space? | He is suffering joint pain, swelling, rashes, vision problems, etc. | Biology | explainlikeimfive | {
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"Low gravity causes problems with our bodies since they were built around an environment where there are certain pressures places on our body from living on Earth. Since he is in space with none of these pressures (namely gravity) his body becomes weaker, his blood flow is effected, pressure on the eyes is effected, etc. ETA: We just aren't built to be in zero g for long periods of time. Its one of the problems that prevent us from going to Mars right now is that it would take a year for a round trip. Thats really hard on our bodies and we haven't come up with a way to counter the effects yet.",
"Spend enough time in space and you start to turn into a jellyfish, not literally. But the lack of gravity causes us to lose muscle definition and strength, bone mass loss, and our eyes start to deteriorate. This is because human beings are meant for Earth's gravity, like all other animals our sense rely on Earth's cues to function."
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7hff56 | Why does 6’ seem so much taller to us than 5’9” when the 6’ man is less than 5% taller than the 5’9” man? | It seems with height, differences which are mathematically small seem disproportionately large to us. Why is that so? | Biology | explainlikeimfive | {
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"It's all perspective. If the person looking at you is 5'6 and you're 3 inches taller, that will look much shorter than someone a half foot taller. Angles of vision, yo.",
"In the U.S., the average male height is 5'9\" with a standard deviation of 3\". Look at what a normal distribution (bell curve) looks like: URL_0 The middle, darkest blue, section, is one standard deviation. Someone who's 6' tall is on the upper end of that. So approximately 84% of men are shorter than that! In comparison, someone who's 5'9 is exactly average. 50% of men are shorter, 50% are taller. When you think of it that way, it makes sense why someone who's 6' seems quite tall. They're taller than most people.",
"Because there’s not a whole lot of variability in height relative to the total height, so even a small amount is noticeable. It may only be a 5% increase in total height, but you live up like 30% up the bell curve of adult males",
"Men don't typically grow to be between 1 foot tall and 6 foot tall. They grow to be usually around 5'5 to 6'5. So those little percentages make a big difference because we don't exist on a scale of extreme differences. There are exceptions but they are few and far between.",
"Say there are 100 random American men. If you looked at someone who is 5'9'', then only 32 men are shorter than them. If you look at someone who is 6 feet tall, then only 14 men would be taller than them. So it's based on how common it is to see someone of that height."
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7hffnb | Why do small water droplets on my smart phone's touchscreen create a rainbow effect when looked at. | Today while I was standing in light rain waiting for a cab, I noticed many tiny water droplets on my phone. When looked though it caused the screen to look like a plethora of colours as apposed to the colour it is meant to be. So I am wondering.. What causes this? | Physics | explainlikeimfive | {
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"It acts like a magnifying glass and zooms into the tiny pixels. It has a cupule shape just like a magnifying glass and works the same way"
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7hfftm | How does the heat of the sun reach earth even though space is a cold void? How does it reach us through space? | Physics | explainlikeimfive | {
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"There's three ways heat can be transferred. Conduction, which is heat traveling by contact. Convection, which is heat moving around as hot fluids rise. And lastly radiation, which is heat transfered through light. Light has no problem going through a vacuum. Radiation is how the sun heats the earth. The entire spectrum heats the earth including infrared and ultraviolet, but the sun peaks it's output in the visible light spectrum (by no coincidence really). It's no different than you sitting by a fire and feeling the heat on you. That heat isn't because of the air between you and the fire, that's heat from the radiation (light, though not necessarily visible, fire emmit more infrared).",
"There are three ways in which heat can transfer: conduction, convection, and electromagnetic radiation. Conduction is your usual fare; touch something hot and your hand will be hot. Convection is when a fluid is heated, which then causes it move away, moving the heat. Both are those, as you already recognize, require molecules to interact with other molecules. Space has a distinct lack of anything, so indeed there is basically no conduction or convection between the Earth and the Sun. Incidentally, this is why you won't freeze in space and why space stations have to spend a great deal of work to remove heat and not vice versa. But there is electromagnetic radiation. Light, visible and not, is also energy, and also heat, and electromagnetic waves do not require a medium. They can travel through the vacuum of space with no issue. The electromagnetic field is fundamental and infinite."
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7hfq5b | How does Google Maps show satellite maps of other planets and moons? | Technology | explainlikeimfive | {
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"We have photos of those celestial bodies from various sources, including high resolution telescopes (for the larger and closer bodies), satellites (for the more explored bodies, like Mars) and space probes.",
"Yes, NASA has sent space probes to orbit the moon, Mars, Venus, and other planets to completely image them. All of the data is freely available to the public, too."
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7hfqw5 | why is it that if you refresh/go back/etc. on some websites it will save information you entered but not on others? | Technology | explainlikeimfive | {
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"It all depends on the site but it has to do with cookies. Cookies are temporary stored information that are saved within the web browser. Some sites make it so if you’re on a certain page (like a sign up one) it will save the information that was assumed entered correctly. It’s mostly used for convenience but when sites don’t use it, it’s because it can be a security risk.",
"Simple answer: it depends how they are written. On a webpage every time you load a page from scratch is a totally new transaction and you've effectively started again. So, by default, when you load a form up again, it will have forgotten, unless the website programmers have explicitly saved what you wrote in last time and filled it in when drawing the page back again. Imagine a conversation between 2 people, one of whom, the Server, has severe face blindness and/or short-term memory problems. Customer: can you please get me the info for URL_1 please? Server: yes, here you go. Customer: OK, thanks. Hmm... Can you get me the info for URL_1 /interesting-news-story please? Server: yes, here you go. ok that's fine, it doesn't matter he can't remember who you are because everyone sees the same stuff. Customer: I want to log in so I can demonstrate to these idiots how correct my opinions are. Server, can you please send this username and password to URL_0 please? Server: Yes. Here you go. [Server sends back a custom page with a delicious cookie] Customer: OK now send this comment to nytimes,com/speak-your-brains \"lol no libtard wtf\" Server: can't sorry, I need to know know who you are. Customer: OK now send this comment to nytimes,com/speak-your-brains \"lol no libtard wtf\" - here is my cookie. Server: [looks at chart of photos of cookies and recognises yours (this is a weird metaphor)] Ah yes, Customer. I will post this and return a page. so actually you need to send the server who you are every time you make a request (that's what's in a Cookie). This won't contain your username and password but it will contain some kind of identifier, so they server will know who you are each time, and will look up and see that you logged in a bit earlier. OR it will see that you filled in part of a form earlier. To complicate things even more, you'll have a cookie given _every time_ you visit a website so you can be identified whether you logged in or not. Er rrr this got really rambling, I'll leave it to others to clarify my incredible mixed metaphor"
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7hfszn | Why does adding money into an economy affect inflation? Why can't prices remain fixed and incomes rise? | Economics | explainlikeimfive | {
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"Imagine that you live in a world where the only thing anybody wants is pizza, and each day one pizza is made, with exactly 100 slices, with varying toppings. There are exactly 50 people in this world, and every day, you dig holes, and for every hole you dig you get a dollar. At the end of the day, the pizza slices are auctioned off. One day, the money god decides to pay everyone two dollars per hole, but no more pizza is made. So now you, and everyone else, has twice as much money. But you all still want to eat, so you all bid twice as much, and nothing in the system has changed except for the numbers written on your money.",
"Counter question. How do you raise salaries without also raising prices? Businesses still need to pay employees their increased salaries and maintain their profit margin. So to be able to pay more money, they'll need to get more money by raising prices",
"What if you gave every single person ten million dollars? Now everybody can afford a five million dollar waterfront mansion! Suppose you are selling a waterfront mansion of your own. Yesterday, you were asking five million dollars and you expected to wait a few months to sell it. Today, your phone is ringing off the hook with offers. So you think to yourself, \"hm I can get a lot more than I could, before.\" So you raise the price to, say, a hundred million dollars. Presto, there is inflation. The same dynamic applies to everything from a loaf of bread to Jeff Bezos's yacht. Sellers are going to charge as much as they can, and \"as much as they can\" is tied to how much people actually have.",
"Back then, when money was not a thing, people would barter to obtain the goods they needed. For example, if I'm a hunter and you're a baker, I would trade animals to get some bread from you. But what if you don't need meat from me, instead, you want that salmon from the fisherman. This is when money becomes a more efficient form of trading, I will just pay you for the bread, and you could take money from me to buy the salmon you want. So money is just a medium of exchange, it has no real value, but instead, it represents the value of goods you have. Therefore, duplicating the money you have doesn't duplicate the amount of goods you own, all it does is increase the price of goods. And that's when inflation occurs. Also remember that money is in circulation, so the total currency out there should be fixed (ideally). The employers can only pay you higher if they make more money. And by making more money, they must increase the prices. Else, there no way incomes can rise if prices remain fixed.",
"First, I'm assuming you're talking about Fiat money and adding it via a central bank. Fiat money is backed by faith, nothing else. Everyone agrees that it's worth something, but there is no hard and fast exchange between cash and a substance with inherent value (gold, corn, gasoline, etc) If you arbitrarily add more of this money, you dilute its value. If we all decided tomorrow that every dollar would be converted into two dollars, the net effect wouldn't change anything. Your bank account would be twice as big. Your bills would be twice as big too. You just diluted everything by half. What if though, tomorrow, someone was given new money equal to all the other money in the world? Well, yesterday, two dollars bought a loaf of bread. Tomorrow, there is twice as many dollars but still the same amount of bread. That load is going to cost about $4 tomorrow. Central banks add money by issuing loans to other banks. Other banks have to keep a certain percentage of money on hand to cover their loans. The central bank does not. If their goal is to add money to the system, they offer loans with rates as low as necessary to get banks to take it. So, if one person has a \"free\" source of money, they can suppress interest rates and dilute the value of money. This probably seems crazy. I think what you really want to have happen is for goods to get cheaper while wages go up. That's more related to the productivity of a society. Bottom line is that businesses have to be profitable. Wages are tied to the value of the work. Costs of goods are tied to inputs. Sure, those rules don't always apply, but the exceptions aren't sustainable."
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7hgakc | What exactly happens when you pass out from pain? | Biology | explainlikeimfive | {
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"What occurs when you pass out from extreme pain is a form of what is known as *vasovagal syncope.* Syncope means to lose consciousness and vasovagal refers to effects on the vasculature/vessels (vaso-) from the Vagus cranial nerve (-vagal). When you experience sudden and extreme pain, the information is sent to an area in the brainstem called the solitary nucleus, which is an input area for several cranial nerves, with the Vagus nerve being one of them. Of the twelve cranial nerves (which almost exclusively supply the head and neck), the Vagus nerve is special because it travels extensively around the body and innervates a wide variety of organs and blood vessels. It is involved in *parasympathetic* control of the nervous system, the branch of the autonomic nervous system that is commonly associated with \"rest and digest\" rather than the sympathetic \"fight or flight.\" With activation of the parasympathetic Vagus nerve, the heart slows down and beats with less force per pump (*rest* and digest). This is combined with a decrease in what is known as *sympathetic tone.* Sympathetic tone helps to keep blood vessels constricted, and when that is withdrawn, blood vessels can dilate. So, a decrease in cardiac output (less blood pumped from the slowed heart rate and contractibility) combined with dilated vessels, significantly reduces blood pressure too quickly and the brain is temporarily less perfused by oxygenated blood, leading to loss of consciousness. **Edit below: More ELI5ish** Sorry to anyone confused by the description above. When you experience extreme pain, your body sends signals to the part of your brain that is the control board for a special nerve that \"relaxes\" a lot of your organs (slows heart, increases gut movement for digestion, etc). This nerve slows your heart down and causes it to pump less blood per unit time *at the same time* that nerves that keep your arteries constricted stop doing their job. So, you get less fluid pumping through wider pipes and, unsurprisingly, this can be measured as reduced blood pressure. Less blood is delivered to the brain, and the person loses consciousness. In the absence of any major bleeding, the body will correct the overshoot and the person will regain consciousness eventually. **Edit #2 - TRUE ELI5** Sudden and extreme pain flips a switch in your brain, which makes your blood vessels relax (by expanding) and your heart rate slow down *and* pump less blood with each beat. This brings less blood (and less oxygen) to your brain and you pass out. Your body fixes it quickly, but after you pass out.",
"As far as i know this is not 100% explained by science. But faint from pain could be triggered as a relaxation reaction of one's body. After severe pain the \"vagus nerve\" influence the vessels. If its influence is strong enough vascular tension, blood pressure as well as puls per minute decrease and one's muscles relax. In extreme cases one's brain doesn't get enough oxygen, the consequence is a so called \"Common faint\". As the designation \"Common\" implied it is a not really dangerous kind of faint. The level of pain that triggers this reaction differ from one to another. Many psychology touched physicians are convinced by this reason. PS This is what i know from my biology education at school. So hopefully one can explain better.",
"Perhaps the greatest faculty our minds posses is the ability to cope with pain. Classic thinking teaches us of the four doors of the mind, which everyone moves through according to their need. First is the door of sleep. Sleep offers us a retreat from the world and all it's pain. Sleep marks passing time, giving us distance from the things that have hurt us. When a person is wounded they will often fall unconscious. Similarly, someone who hears traumatic news will often swoon or feint. This is the mind's way of protecting itself from pain by stepping though the first door. Second is the door of forgetting. Some wounds are too deep to heal, or too deep to heal quickly. In addition, many memories are simply to painful and there is no healing to be done. The saying \"time heals all wounds\" is false. Time heals most wounds. The rest are hidden behind this door. Third is the door of madness. There are many times when the mind is delt such a blow it hides itself in insanity. While this may not seem beneficial, it is. There are times when reality is nothing but pain, and to escape that pain the mind must leave reality behind. Last is the door of death. the final resort. Nothing can hurt us after we are dead, or so we have been told. > TNOTW"
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7hgbqd | What makes something fun? and why are some fun things dangerous, like parachuting | Other | explainlikeimfive | {
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"For parachuting and other dangerous stuff, it releases adrenaline which makes you feel good essentially."
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7hghyx | What are different poisons made of to make them more or less poisonous? Mostly on a molecular level and happens to the body on a cellular level when poisoned?(i.e. Ricin) | Chemistry | explainlikeimfive | {
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"Things that are poisonous are usually those that inhibit some important bodily function in some way. Take, say, a neurotoxin, is something that will prevent your nerves from functioning properly, which is a very big problem indeed. Some poisons block bodily processes by getting in the way, acting as enzyme blockers (enzymes are active molecules inside your body that help get specific things done by binding to certain molecules and doing something to them. If some toxin binds to an enzyme which is can't process, the enzyme can't do its job anymore and you have a problem), or by destroying important cells. It all depends on the poison in itself, and what bodily function specifically it creates a problem for. That's why neurotoxins are a very potent type - your nervous system is generally very important. Ricin specifically messes up the ribosomal RNA within your cells, which blocks protein synthesis, and various proteins are very important to our bodily function."
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7hgltc | When you remove a tumor, does it leave a gap in the organ/tissue it was removed from? | Biology | explainlikeimfive | {
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"Yes, it does. What happens depends on the regenerative power of the type of tissue that the tumor is removed from. With the exception of the liver, our organs do not regenerate so if your remove any part of them that's it, it's gone. Usually when there's surgery involving tumors, they remove the tumor and take a little bit of the surrounding healthy tissue as well so they're ensuring they get all of the cancer. As a result, you're left with a gap in your body that either is permanent and the surgeon closes off (such as if it's an amputation) or that part fills with fluid (as is the case with a removed volume of cerebral material). Things may change further over time as your body reacts to scarring in the area or a large volume of material is removed from your internal tissues and there's no longer rigid structure there to support them. It's kind of like how the hole from an extracted wisdom tooth eventually fills in. [edit: adding one other option - a transplant or graft. They can introduce replacement living material like a tissue graft or transplanted organ to replace the area you lost, or they can introduce something like a 'scaffold' graft of sterilized bone tissue that your body can incorporate into itself.]"
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7hgo0m | How are space stations cooled? | Physics | explainlikeimfive | {
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"The ISS cools itself using black body radiation as convection don't work in a vacuum. [To do this it uses huge radiator panels that radiate heat into space]( URL_0 ).",
"[Here's a pic of the ISS]( URL_0 ) Notice the white panels that kind of look like solar panels? Those are aluminum cooling radiators. They have ammonia circling though them similar to liquid cooling in your car or in a pc. Ammonia is used instead of water though as water could freeze where as ammonia starts to freeze at around -110C. This is circulated continually extracting the heat out along them and radiating it away into space."
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7hgwsa | When burning stored fat, how does the body prioritize where to burn it from. | Biology | explainlikeimfive | {
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"Basically, your body has two main mechanisms for burning energy: - Burning glucose for energy - Burning ketones from fat for energy (ketosis) As far as where to burn it from, it's largely genetic. 'Spot' reducing targetted areas of fat won't work, your body will decide where it wants to take its fuel from. Chances are it will prioritise fat from the extremities (legs, arms etc) first because it's not protecting vital organs (heart, lungs etc) (as far as I'm aware). Hope that helps!"
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7hh17v | How does the moon appear bigger on some days and smaller on others if its orbit remains the same? | Physics | explainlikeimfive | {
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"There actually are slight difference in the distance between the Earth and the moon depending over time but you can't see them with the naked eye. The reason the moon sometimes looks bigger is an illusion. When the moon is high in the sky you don't have any nearby objects to compare it to so you only judge it's size based on the angle it subtends. But when the moon is close to the horizon your brain compared it to objects that subtend a smaller angle than the moon does so it ends up looking bigger.",
"Good illustration of the illusion from Wikipedia: URL_0"
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7hh1ul | What is the difference between a normal derivative and deriving on a particular point of a function? | The normal derivative is on a particular point too, I know that, but how do you "decide" where to derive it? | Mathematics | explainlikeimfive | {
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"On nice functions you can apply normal rules for derivatives to get a value or a function describing the derivative *everywhere* ( if you get a function and not a constant as result, you just insert the point you want to know the derivative of in the function to know the derivative of that location. But all functions are not so nice, some functions don't have an analytic description of their derivative, then you can go back to the definition of derivative and calculate it on a point, i.e. look at the value difference if you take a small step h forward, divided by the step length, then make h as small as you can without becoming zero. As to deciding where to derive it, you probably have a reason why you need to calculate this derivative, from that reason it should be obvious (although the answer may be \"every point\") - if you don't know where you need the derivative, I don't know why you'd want to calculate it in the first place!",
"When you take the derivative of a function, you get back a function that describes the derivative of every point on the original function. So you don't decide any specific place to derive it - you derive it everywhere."
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7hhcmn | When we lose a game, why does our body feel a sense of failure even though it's not real? Why does our body accept failure at all? What's the point of such a negative emotion? | Other | explainlikeimfive | {
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"We feel the defeat of failure for the same reason we feel success. Knowing that we failed can drive us to try harder next time in the same way that succeeding makes us want to do it again. Sometimes, however, you don't know what you did wrong or how you could've done better, and all you feel is crushing defeat. when that happens, its the same reaction as when something in real life makes you sad, like breaking your phone. That's your body telling you that that thing is bad and should be avoided in the future. You'd be more careful with your second phone after you broke the first one, and you'd avoid a game that you've lost repeatedly (Think of a child who loses a game, then doesn't play anymore because 'the game is stupid')."
],
"score": [
4
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7hhj9e | Why do we die in old age? What makes the body/mind stop working when we're old? Why could we not live eternally with pacemakers implemented? | Biology | explainlikeimfive | {
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"text": [
"There's a lot of different things that make us die in old age. One of these is called telomeres. They're little chunks of extra DNA on the end of chromosomes, and each time a cell reproduces it loses one. When they run out, cells will stop growing/reproducing and sometimes self-destruct. Telomere shortening is associated with many age-related diseases. Another thing that happens when we get old is our lysosomes start to become less effective. Lysosomes are basically the garbage disposal in your cells, responsible for breaking down chemicals the body doesn't need any more. Recent discoveries have associated aging with a decrease in lysosome efficiency, which results in buildup of unwanted material in cells resulting in damage. There's no one answer, sadly, which is why people who study aging with the intent to combat its effects have a lot of different routes to pursue. EDIT: In a more practical sense, there is little evolutionary pressure to live longer than our bodies currently do. By the time we're old enough to suffer from age-related maladies, we have generally performed our function of producing offspring and raising them to the point where they can take care of themselves. It is a more efficient use of resources for the elderly to die once they are no longer useful. That doesn't really hold true today, but we're still dealing with the hand evolution dealt us.",
"We never really die of old age, we just succumb to a disease or something that our body has become less resistant against. Becuase our bodies are weaker we die from small things easier. So overall we really don't die of old age. The older you get from like fifty the weaker you get."
],
"score": [
9,
6
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|
7hhm4w | How sewage treatment facilities clean water. | Chemistry | explainlikeimfive | {
"a_id": [
"dqr0oq5",
"dqrxwrr"
],
"text": [
"After removing the solid waste out of the sewage using filters and screens, most of rest of the sewage is stored in pools that allow bacteria to break down the waste materials in the water. After more filtering, the water is treated with anti-septics (usually chlorine) and sent back into the environment.",
"Instead of using chlorine (incredibly dangerous gaseous chemical) some smaller plants use high intensity UV light (think of a tanning bed on crack) to purify the outflow. In my area, treatment plant are subject to daily testing of the outflow, so I'm not sure if they could actually \"get away\" with dumping raw untreated outflow into a local body of water. The state level authorities and EPA would be on that like flies on shit, pun intended."
],
"score": [
7,
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7hhqzv | Why do we take fever suppressors, like Tylenol, when we have a fever, why don’t we just leave the fever and let the high temperatures kill the bacteria? | Biology | explainlikeimfive | {
"a_id": [
"dqr2nq7",
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"text": [
"Two reasons - 1) Raising your body temperature is a dangerous and relatively ineffective way to kill pathogens since it can also harm your own cells. Other immune responses like antibodies and phagocytes are much more effective, and 2) Fevers suck and are very uncomfortable, so fever suppressors are useful for providing pain relief. This is especially true when the infection is moderate and when used in combination with antibiotics",
"[According to the American Association of Pediatrics, you should allow most fevers to run their course without medication as they are beneficial to fighting infections.]( URL_0 ) People take fever medications to make themselves feel more comfortable, whether it's because they need to be functional adults or because they simply don't like how fevers feel. They give their children fever medications for the same reason; parents especially do not want to see their children in pain. Fevers do not become dangerous until they are over 103 (in adults, the number changes for children and infants), at which point you need to *go to a hospital immediately*. Do not attempt self medication. As someone else in the thread mentioned, if the fever gets that high this is a sign of brain damage. Anecdotally, when I've taken fever medication I am sick for much longer than when I haven't. Granted, day to day it's more tolerable, but the sickness lasts for so long that it simply isn't worth it. I'd rather take a day or two off of work and let nature run its course."
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"http://pediatrics.aappublications.org/content/127/3/580.full"
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|
7hi1a6 | Why do countries import oil when they at the same time export oil ? | Why don’t they just use the oil they have to import less ? | Economics | explainlikeimfive | {
"a_id": [
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"text": [
"There's a few reasons: Lets use the USA as our home country 1- Location. It can be difficult to move boats long distances, as well as expensive because of treacherous waters and longer distances We get 1 barrel from the us for 50$ and sell to china for 60$. Venezuela gets 1 barrel from their ground for 20$ and sells to the us for 40$. However, because they have to bring that oil all the way around South America, they would have to sell the oil for 70$ to be profitable. Therefore, the US makes 10$ selling to China, and saves money buying gas from Venezuela rather than using their own. 2- Economic stability If the US purchases oil from the Middle East, they may not want to get into wars because all the countries are being profitable. However, if the US and other countries suddenly began only using their own oil, the economies in the Middle East could collapse causing political stabiilty, and could lead to warring nations who aren't happy with their countries failing economy. 3- Trade agreements The US may agree to buy 1 billion gallons of oil minimum every day from Saudi Arabia in exchange for keeping open trade and other agreements. Additionally, this policy could be done to maintain allies between countries",
"Because there are different grades of oil and different refining capabilities. The US, for example, generally has higher grade oil reserves and also has some of the best ability to refine low-grade oil. If they sell expensive high-grade domestic oil, and import cheap low grade oil they can refine, they come out ahead.",
"Crude oil is useless. It has to be refined to turn it into usable products (fuel, chemicals, plastics, etc). The US has a LOT of refining capability, so we import oil, refine it, and then export the end products. Its also important to keep in mind that the USA doesn't have any single entity in charge of this. Different companies each make their own decisions about where to refine and sell their products. Depending on what the market looks like at any given time, companies may shift their shipments to different ports depending on prices, supply/demand, refining capacity, storage capacity, etc",
"Geography plays a role as well. In Canada, most of our oil Is produced in the western part of the country. It is currently more economical to ship that oil south to American refineries then it is to send it al the way to the east coast where our refineries are. Those refineries are buying mostly middle eastern oil as it is cheaper (currently) to produce and ship that oil here then to use our own.",
"Crude Oil doesn't operate industry; it needs to be refined into usable products. The production capacity for refining these fuels will fluctuate based on how many refineries are active versus undergoing maintenance. And the consumer and industrial demand for these fuels changes their value over the course of months or years. So some countries export some petroleum products which they may have an abundance of, and import others if it's cheaper than making it themselves. For instance imagine a situation where out of 1 barrel of crude oil you get 50% automotive fuel in the form of gasoline or diesel, 40% heating oil and 10% lubricant oil. But lets say that this is in a country which has very gentle winters. They need a lot of auto fuel for their economy, but have no need for the heating oil. If they kept using their own crude oil to produce auto fuel, they would end up with all of those other products just sitting there with no use, and it's value would be low in that country because nobody would need it. Meanwhile their production capacity for automotive fuels has been reached, and so they need to import more. They could sell their heating oil to countries that need it, in order to buy or trade for automotive fuel. This is a simplified example but the reality is much more complex and needs to factor in demand, supply, the obstacles faced in transporting it, production capacity of refineries, and technological advances such as in cracking heavier fuel oils into lighter fuels like gasoline."
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8,
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7hi52b | What is that smell right after a good sneeze? | Biology | explainlikeimfive | {
"a_id": [
"dqr8ay5",
"dqr6yk7"
],
"text": [
"Sneezing increases pressure in the sinuses. If the person has sinusitis, this can create an unpleasant odour both for the sneezer and those around. The reason is because the sneeze can force fluid caused by bacterial sinusitis into the nasopharynx. So you are smelling bacterial by product caused by infective sinusitis. Nice.",
"Everyone's sneeze smells are different. Some people that have sweet smelling honey or floral smell are due to the ketones in your bloodstream. (sometimes a sign of diabetes or liver disease if it smells like ammonia). Others might have a foul smell due to smelly saliva. Since saliva is forced out of your nose and mouth when you sneeze, this might be the smell you're smelling. (i.e. the old saying of you are what you eat might come into play here)."
],
"score": [
3,
3
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|
7hjg3v | How does an AED work? | Biology | explainlikeimfive | {
"a_id": [
"dqrgo6e"
],
"text": [
"It has a computer programmed to recognize the specific conditions when a shock will get a heart out of fibrillation. It is designed to be easy enough for anyone to open it and apply the leads. There are diagrams. It gives verbal instructions. The leads sense the heart signals normal ECGs detect. If the heart is quivering uselessly it will say \"Stop CPR\" then administer a shock The shock may restore a normal heart beat. Do not be afraid to use it. Trust it. But you may just have to do CPR if the problem is not fibrillation Most EKG machines can diagnose a lot of things now. So they created one to diagnose the one thing which a shock will fix."
],
"score": [
3
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7hjiz4 | why does heat sometimes soften and sometimes harden metals? For instance, smithing metals makes them easier to bend, but factories heat metal in a furnace to harden it into shape. | Chemistry | explainlikeimfive | {
"a_id": [
"dqrhloy"
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"text": [
"As for smithing: Glowing hot metal is soft. You hammer hot metal, it kneads Because metal has a structure. You heat metal, structure changes. Say, from structure A (cold), to B (hot) You leave hot metal cooling down over time, structure slowly changes back from B to A You take hot metal and immediately put it on water, metal cools down too fast for structure to change back So metal cools down, but keeps the B structure This is hardening, makes tempered metal hard, but brittle So metal goes to oven, to heat and cool slowly to become just a bit less brittle. This is tempering"
],
"score": [
12
],
"text_urls": [
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} | [
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