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921ine | Technology | How is it possible that my car keys unlock only my car and not all the others? Is it theoretically possible that my key could unlock a second car somewhere on the world (given I'm close by)? Edit: Apologies for the poorly phrased question. While the mystery of mechanical keys is fairly interesting I always figured that there would be a limited amount of key/locks available. My question was particularly referring to the (new) wireless keys!! | The key fob uses a rolling code that is stored in the fob and the security section of the ECU or immobilizer unit. The fobs are all registered at the same time and they all use a separate rolling code (multiple codes per car, sometimes 5 or 6 possible fobs) So you press unlock and the fob calls out to the car, the car answers and asks for a code and the fob replies with the code that the car is expecting. There are a buttload of combinations so it is VERY unlikely that it can unlock another car BUT it has been done before. It's often a lot more complicated when you have proximity unlock (smart entry), remote start, etc etc. The fob ID can also be used to preset stuff like mirror position, seat and steering position, etc etc. So you have your fob with your settings and your partner has theirs. You can both lock and unlock at the same time because the knows both fobs. edit: there are a boatload of different ways that fobs communicate with cars across different manufacturers. Basically the fob and the car know the same secret handshake. they do a little secret handshake with each other when you ask the car to lock and unlock. The secret handshake is always changing though so I can't watch your handshake and then try it with your car, it'll know that that handshake is old and lame. | 12 |
6ullbb | Physics | Energy cannot be created nor destroyed, and it is impossible to get out more energy than you put in. That said, how can nuclear weapons, and bombs in general, generate sooooo much explosive output given their small size relative to their huge explosions? | Because the energy put into creating heavy elements (like uranium) is very high. So when you convert it back into lighter elements you get a lot of energy out. its like if you have a bicycle hooked up to a generator which splits water into hydrogen and oxygen via electrolysis, and then when you have done it for a long time and have a lot of hydrogen and oxygen split from each other, then you can get a lot of energy from igniting it and letting them form back into H2O. Most heavy elements (heavier than iron) were made in the cores of supermassive stars at the point where they exploded in a supernova. Some of the heavy elements were made when objects crashed (especially stars colliding into each other after circling each other for a long time), because the area between the cores becomes super-energetic due to the area being compressed. Sort of like the air in front of returning spacecraft being compressed and super-heated, but with cores of stars instead of a tiny capsule. And the atmosphere they compress is already thousands of degrees when beginning the compressing. That being said, nuclear fission and fusion bombs are actually not very efficient, you only get a small portion of the energy out. If we were to make an equal size anti-matter bomb compared to a nuclear fission bomb, then the bomb would be thousands of times more powerful because the entire mass of the core of the bomb would be converted into energy, instead of just a fraction of the mass of the core. | 3 |
8pzs66 | Other | If pasta is made of the same things (flour, egg, water), whats the point of the dozens of shapes? | Sauce aside, texture is an integral component of taste, that's why people find mushy bananas revolting. Different shapes will have different textures | 12 |
fz0yn5 | Biology | If our bodies need sleep to function properly and you wake up in the middle of the night, why does our brain keep us up instead of putting us back to sleep? | "If our body needs food, how come we don't stop to eat when we're being chased by a tiger?" If you're awake in the middle of the night it's because of some kind of perceived threat. Whether physical danger, or a stressful event of some kind, your brain doesn't feel like it's time to go to sleep. | 9 |
csuds6 | Biology | why we get a "second wind" if we go too long without sleep. | Long time without a sleep is a stress for your body. If this stress reaches certain threshold, your body treats such situation as danger and starts producing adrenaline which prevents you from falling asleep quickly | 4 |
d623lh | Other | What exactly does “passive aggressive” mean? | OK, that's fine. Just ask us all to do a google search for you and read the answers, it's really not a problem. | 3 |
g79hjs | Other | If so many white-collar jobs involve learning on the job, was there any point to doing a degree? | If a job requires you to learn C on the job, but to learn C, you must already know A and B, then you need a degree to learn A and B before you can learn C. Most jobs are like this. You learn industry practices and new knowledge that you don't learn outside of working, but having existing knowledge help you learn that. There are jobs where you get a degree and its completely unrelated to the job meaning the degree was just to show that you're able to get through college | 4 |
8b9b8f | Physics | Forced Vibrations and Resonance So I'm currently studying engineering and in Physics we are studying waves, but i¡m not quite understanding it completely. So I'd like some to explain it to me in a "non-conventional" way that otherwise, I wouldn't get from my porfessor. Thanks in advice! | I like thinking about it in terms of a bathtub. Imagine you're sitting in the tub (or go get in a full bathtub for the full effect!) You're splashing your hand in the water, making waves. The waves spread out from your hand, bounce off a bathtub wall, and come back to you some time later. If you smack the water once every ten seconds, you'll make a wave, it will rebound, and it will have totally died out by the time you smack again. If you smack the water as fast as you can (or more precisely, as *frequently* as you can), you'll make a mess, but there's nothing in there that's going to be recognizable as a wave, because each new wave is just running over the last and the ones that are bouncing back. But somewhere inbetween those two there's a frequency where you'll see that the wave you make by smacking the water just perfectly lines up with the wave coming back at you from the last smack. The two waves hit each other and add together, making an even *bigger* wave. If you keep going at that exact rate of slaps, you'll get bigger and bigger waves, as each one adds to the last. That's the "resonant frequency" of the bathtub. From the engineers perspective (note: I am not an engineer) you'll find that the resonant frequency depends on the length of object (it'll take longer for the wave to reflect back to you if you have a really big bathtub) and also the material (the wave is going to behave super differently if the bathtub was full of, say, jello). Does that make sense? Let me know if that isn't enough detail, or wasn't super clear! | 2 |
n66orf | Biology | Can insects, crabs, spiders, and other animals with an exoskeleton become overweight or obese? If so, how does it work? Do they just molt into larger skeletons? | Vertebrates usually can’t swap in a larger skeleton when they get too heavy, and so they just expand outwards and get fat. Arthropods *can* molt into a larger exoskeleton when they’re getting a bit snug, and so instead of getting fat they actually get taller and stronger. Your typical American lobster is about a foot long and five pounds, but once in a great while fishermen will catch a three foot long, forty pound monster that has been outcompeting everyone else for decades. These beasts get thrown back in, as they’re the kings and queens of the breeding cycle and keep the population up. Land arthropods are more limited in size because their heavy armor and inefficient respiratory systems don’t scale well. | 7 |
6n7f8e | Repost | Why does certain food have to be refrigerated after opening? | When many types of food are packaged, it's done under sterile conditions - so that bacteria or fungi can't grow in it. As soon as you break the seal of a package, you introduce bacteria or fungal spores into the food. At room temperature, microorganisms like to thrive. At refrigerator temps, it slows or stops the growth of these microorganisms. Not all types of them, just most. | 1 |
8b9g0l | Mathematics | You are on a game show with a prize behind one of three doors. You choose a door, and the host opens one of the other two doors showing you there isn’t a prize there. You should now change your decision. WHY?! (the most infuriating statistics problem that I still don’t understand) | > I CANNOT get off the thinking that if you now know the prize is a 50/50 choice, changing your original guess gives you no statistical improvement. To me, the original probability of a 1/3 guess has no bearing when it has been reduced to a 50/50 guess. Imagine instead that you have 100 doors and one prize. You pick a door and the host opens 98 doors showing there is no prize behind them. Do you switch? Of course you do because it is unlikely your first pick was correct. Similarly the first pick from three doors is 1/3, so the remaining door after the reveal is slightly more likely to have the prize. | 4 |
92cvrc | Other | Who at the airline is actually empowered to give you compensation to be bumped from a flight and how do they determine how high they will go to get you off the flight? If you read Reddit you will hear crazy stories of high compensation for being bumped from a flight. Who decides at the airline how high they will go with the compensation and what is their incentive to keep it as low as possible (ex. do they a certain bucket of funds that they have for each flight). It seems like a lot of power to give to certain persons at the airline. | The gate agent is the one who can do this. Before they bump anyone, they will ask for volunteers, and this is where negotiations can come into play. As far as how high they get to go, that's pretty easy: if you are *involuntarily* bumped, federal law (in the US) specifies how much they must pay you: * If they get you to your destination within an hour of your original schedule, nothing * If they get you to your destination between one and two hours (for domestic flights) or one and four hours (for international flights) of your original schedule, 200% of the one-way fare, up to a maximum $675. * More than two hours late for domestic or four hours late international, 400% of your one-way fare, up to a maximum $1,350. Note that when involuntarily bumped, they must pay you with a check -- real money, not credit with the airlines. Knowing that, you know that the gate agents will never offer more than that, because they don't have to -- if nobody takes the lower offers, they bump people and pay the legally required rate. Though the airline would much rather pay you in credit than cash, so they could be slightly more generous in flight vouchers. | 2 |
5ymsmn | Repost | Why are all the planets spherical? | Imagine you had a non-spherical object the size of the earth (let's say, it's a Cube instead) Well, in that case, certain parts of the cube (the corners) would be farther away from the center of mass than other parts (the center of the faces). Because the corners are farther away, they have more potential energy (the same way a brick on top of a building has more potential energy than the same brick resting on the ground). Now Gravity is trying to crush everything into the center (it's just what Gravity does, attracts mass towards other mass), the areas with higher potential energy have a higher likelihood of 'Falling' from their elevated position to a lower 'Rest State'. As this 'Falling' action occurs (over vast periods of time), your Cubic-Planet would crush itself into a Spherical-Planet, where all points on the surface experience the same gravitational force. (Sidenote: other's have already pointed out planets aren't spheres, they're spheroids. This is because the rotational energy counteracts gravity more at the equator than at the poles) | 5 |
6okwxk | Culture | How do steakhouse restaurants cook so many steaks at the same time to varying degrees of done-ness and get them all relatively correctly cooked for each customer? Edit: you guys are blowing my mind with your answers. I wish I could give you all golds, seriously, for some reason I find this fascinating. | I worked at Texas Roadhouse for 7 years as a broiler through college. Most of what everyone has said is true so I will not further contribute to the explanation. However this post has given me PTSD of an overflowing Epson printer, 25 minute ticket times, and a too serious manager trying to fix the bottlenecks by screaming profanity at employees instead of physically helping. | 10 |
9228b0 | Physics | Why does the air from fans feel cold, even though its just the same hot air being blown at you? | It’s the cooling effect of evaporation that you feel. It happens naturally anyway but moving air increases the effect many-fold. | 2 |
8vgnc3 | Technology | how are we set to release 5G soon if we haven't acheived true 4G? | The standard starts with a wild milestone that shows the path technology should progress at. Also it just states what the technology is theoretically capable of. What is important between the standards is the implementation or the changes it brings. This could be a change in modulation or the protocol that is used. | 9 |
nudzwe | Physics | What physically is the difference between a charged particle and a non-charged particle or electron? | You can't have an electron without charge. Charge is intrinsic to the particles, if you change it enough to not have a charge then it becomes a different particle. A proton for example with a positive charge is composed of two up quarks and a down quark. A neutron with no charge is composed of one up quark and two down quarks. An electron is elementary, it has no smaller parts. | 4 |
98s2p9 | Biology | Body makes cancer cells everyday, why don’t we have cancer? So I heard that our body ends up producing 1000’s of cancer cells a day due to copying errors, and if that’s true why don’t we have cancer? What causes a cancer cell or a group of cancer cells to be classified as cancer? Thanks for any explanations | Because you have multiple layers of protection against cancer. You need multiple of those copying errors in a single cell. The cell also detects and repairs these errors. If it can't repair them, the cell kills itself. If mutations bypass all of these, the cells have a string of repeating genes at the end of each strand of the cells DNA, and some of these are lost with each copying, and if they all are lost, then the next copy looses actual working genes, and so it dies. So if a cell starts duplicating endlessly, it will soon die. So in order for one of those thousands of copying errors to create a cancer, then it has to be paired with many other ones in the same cell, and some of them within a limited time frame. | 4 |
ctrz1i | Engineering | How can one key work across multiple doors that don’t have the exact same lock? For example, my house key also opens my apartment’s garbage room. | Locks usually have small pins that are cut in two at a specific height. Different heights are how a key is matched to a lock; the split is aligned with the edge of the rotating lock cylinder. In master-keyed locks, one or more pins have two cuts instead of one. Either cut being aligned with the edge of the cylinder allows it to turn, effectively making the lock work with two different keys. | 1 |
o0e7tv | Chemistry | Why does bleach make things white? | Most dyes are rather complex organic molecules, which need to have a very specific structure in order to have color. Bleach is just a strong oxizider, it oxidizes those molecules and alters their structure enough to make them lose their color. | 1 |
m8b87i | Physics | How does gas collect so much that it creates an entire planet? | There are four forces in our universe. You've probably heard of two of them (gravity and electromagnetism). (The other two forces are called the "strong force" and the "weak force," and they operate over very short distances. The strong force and weak force are mostly interesting to nuclear scientists.) At large scales, gravity and EM are the two most important forces. But electrical charge can be + or -, and both kinds of charge occur in equal numbers. Which means the + and - EM forces tend to cancel out over huge distances. That leaves gravity. We use the word "mass" to refer to "gravitational charge." Unlike electrical charge, mass can only be positive. So unlike other forces, it's easy for gravity to add up over long distances. If you have a giant planet-sized spread-out cloud of gas or dust or rocks or any kind of matter, each little bit feels gravity pulling it toward each other little bit. These little pulls don't totally cancel each other out. All the little bits end up getting pulled toward the average position of the bits. (That average position is called the "center of mass" or "center of gravity".) Over a long period of time, often a whole bunch of little bits end up all clumped together in a single object. When the clumps get big enough, interesting stuff starts happening. A big enough lump of hydrogen gas will start turning into helium, a process that releases huge amounts of heat and light -- that's what a star is. Smaller lumps feel the pull of the star's gravity. A lot of lumps simply get sucked in and become part of the star. The remaining lumps go into orbit around the star following a circular path (or sometimes elliptical) due to the balance between the lump's velocity and the pull of the star's gravity. If an orbiting lump is big enough, its gravity will be strong enough that any nearby lumps either get sucked into it and become part of it, or get flung away from it. Over the decades, astronomers studied a bunch of space lumps, and at some point they decided they needed to think about how to classify them. So in 2006, astronomers decided that, in order for a lump to officially be declared a "planet," it had to be big enough to clear all the other lumps out of orbit this way. Pluto failed the requirement, so its "planet" status was revoked, which made a lot of Pluto's fans sad. | 3 |
67urfr | Biology | Why is it so easy to fall asleep in the afternoon but so difficult to fall asleep when it comes to bed time? | As a lifetime poor sleeper I wanted to chime in with something that has been such a big help for me. When you are laying down head on the pillow, don't think about life. This has messed up things for me for years, I never tried to control my thought patterns. Today I will not let my mind wander and I do this by using a trick. Think back to a time you took a hike, walked a route to school, were driving a familiar route etc. Then force your mind to "revisualize" that walk. For instance, I remember my old bus route when I was a kid. I picture myself lying there, listening to the Diesel engine, looking out the window at the trees etc. It's made a world of difference for me but takes some getting used to- if you find yourself reverting to life thoughts again, stop and start over. I'm sure this will get buried, but I just wanted to throw it out there for anyone like me. | 13 |
b9n46n | Other | i really dont get how art commissions work. Like do you pay for the person to make the art or do you pay for the art or for the raw file? I found it confusing how the artist also uploads the art he made for a buyer. So technically the artist makes it available for the public for free? | It's usually posted on their website so they can show their skills off but they usually watermark it so it's not really available to the public for free. Technically it's like you're paying someone to make it but the person who makes it still holds the copyright to it. Unless a gallery pays for that. Usually you're paying for an image. | 3 |
8by5l4 | Technology | How were old game developers able to playtest their games if the games were far beyond current technological capabilities? | The games are not beyond the current technological capabilities. They simply require the bleeding edge best hardware in order to run the highest graphics settings at a good frame rate. In the past the biggest issue with this was that nobody really made really high end gaming PCs that you could just buy from the store. Alienware was one of the only companies that built gaming PCs, and they were mid-range at best, and extremely overpriced. So you had to build your own. Add to that high end hardware is expensive. So you have a technical as well as a financial barrier to actually even get a high end gaming PC. So at the time there would be very few people who would even have the means to run those games maxed if they wanted to. Then consider most of the people who could both afford it, and had the knowledge to do it, were older nerds who might not have much time for games anymore... So what you have is a market where real high end gaming PCs are extremely rare, and pretty much out of the question for your typical gamer. Because of that many people might say that those games are beyond the current tech, even many games journalists might make a reference about those games being designed for the next gen, but they are fully capable of running on the current gen hardware, given that you could afford it and build your own system. | 24 |
ck2eh1 | Biology | how low pain tolerance and high pain tolerance works | God I’m trying to ELI5 and this one is so hard. The biggest contributor to the tolerance thing in my opinion is the memory of pain. There is a whole bunch of things that happen in the body when you are hurt to tell the brain you are hurt. This is “pain”. But the way you feel when you get hurt is the combination of the actual pain signal, and how your brain understands the signal. When people get hurt badly it affects the emotional part of the brain that responds to fear - this is a safety mechanism to make us afraid of things that are dangerous and hurt us. In the future, the same experience may cause fear, to avoid the danger that caused pain. The emotional part of pain and the memory of the situation will affect future experience. For example someone who is very afraid of the dentist because of a terrible cavity as a kid will be afraid at the dentist. This fear can actually increase the pain signals that get through to the brain and increase the amount of pain that is felt for the same amount of pain signal. Overall, one big reason people experience pain differently is their own experience and memory affect how their brain feels pain in a certain situation. Getting away from things a 5 yo would understand - one reason the above is so important in treating pain is that factors that are emotional and not related to pain at all also affect many of the same areas of the brain as these past pain experiences. For example, people with depression or anxiety are more likely to experience chronic pain - certain areas of their brain can become sensitized to a pain experience more easily because of the other factors affecting fear, memory, etc. Getting a bit off topic, my explanation is why when someone says “I have a high pain tolerance” it usually means they don’t (source am a physical therapist). This person is thinking a lot about pain, their experience of pain, how much pain they have - all these things actually predispose the person to feeling more pain from the same experience than someone who is just oblivious or new to the experience or situation. [ edit: this last part was meant to be lighthearted : As a side note, stop telling your physical therapist you have a high pain tolerance. It’s for their safety. Their eyes might roll so hard they go blind.] | 25 |
blgmds | Engineering | What is a sewer system doing wrong when methane gas builds up? You see these videos all over reddit of kids and adults dropping matches or something on fire into a manhole, only for it to result in an eye-popping explosion of methane gas. It makes sense that a sewer could have methane gas from organic waste decomposing, but my question is what is done to prevent that and why is it so often not apparently prevented? So that is to say, that *should* be done to prevent methane buildup in a sewer system and why isn't that done reliably? | Improper ventilation can cause the buildup of sewer gases. I believe that stagnate water in the sewers also contributes a lot to the build up of sewer gases. This is usually caused by blockages such as when too many people are illegally dumping oils and solid items down the drain. | 1 |
apg48a | Biology | Is missing REM sleep bad for my health? | I believe the consensus is that REM sleep is when the brain absorbs or processes all its input of that day. I know that in psych studies lack of sleep does contribute to irritability, anxiousness, becoming scattered minded, and in extreme circumstances death. | 4 |
6fkwww | Biology | What actually happens when you go through ego death on psychedelics? Some people in high doses of LSD or Mushrooms have experienced a feeling of not being themselves anymore and going through the death of their ego. They then come out of the trip a different person. What happens inside the brain/what makes this happen? | I 100% agree with the comments already posted, the best way I can try to describe it in words is that it must be similar to whatever mechanism occurs during vivid, intense dreams. During a strong dream you almost feel like being in an entirely new realm, you don't remember the real world at all. [It has been shown through brain scans that LSD users experience a "more unified" brain, similar to the brain of a young child]( URL_0 ) We dont know nearly enough about the brain to be able to answer for sure sadly. But if you ever have the chance to try it for yourself, do it. It is one of the most beautiful experiences I've ever had. | 8 |
a9hb8i | Biology | What happens to headaches when we go to sleep? | For tension headaches, your muscles naturally relax when you're asleep so often it's enough to make the headache go away. To expand a bit, tight muscles sometimes agitate neighboring nerves which causes pain in different areas around the head. Hence why muscular tension can cause headaches in the first place. | 11 |
cygvpw | Biology | How do fruit flies suddenly appear when fruit is starting to rot? | Why do fruit flies Suddenly appear Every time Rotten fruit is near? Just like me They long to be Close to food! | 8 |
8np6hz | Culture | What's the reason behind of 666 being the number of the beast? Both biblical and anthropological,if posible. | There’s also a musical connection to that number as well. An interval of 6 semitones produces a tritone which is the most dissonant of intervals and called the devils interval a long time ago. Used in metal music and horror movie scores to create tension. An interval of 7 semitones is a perfect fifth and sounds beautiful by contrast. | 12 |
8sl3bl | Economics | Why do all home loan interest rates change on the government end and why do all banks follow the recommendation as it does and not compete with their own rates? | Banks can earn a small amount of interest by letting the government hold their money. The government is very stable and unlikely to default, so this is widely considered the safest investment. Unlike the government, you are a risky investment. The banks will still loan you money instead, but will expect a higher interest rate to account for the greater risk. As the government rate changes, mortgage rates tend to follow. The best mortgage rates will be still higher than the government rate. The banks do compete on rates within reason, but they're all using roughly the same math to decide who gets what rates. People with better credit histories get the lowest rates. | 2 |
mnp4uh | Biology | How do cells multiply? I’m asking because I don’t understand how a cell can multiply in to two and have the same equal mass | Because the cells can also eat whatever food is nearby to regain their mass, until both are at optimum size. Yes, mitosis splits the cell into two half-mass pieces. But nothing is forcing them t stay that size afterward. --Dave, cell-level immortality | 2 |
gplfjx | Other | Why is it illegal to stream a movie on an unofficial site? | There are several possible situations 1) Kohl's or their parent company paid for the rights to the movie owner to show the movie in the store. In which case, Kohl's has specific rights according to what they paid for eg can show in store but not online. This is pretty unlikely. 2) Some employee at that branch decided to play the movie without permission. In this case, it is illegal. Even if you, for example, bought a DVD of the movie, this does not confer the right for you to publicly broadcast it, stream it online, or to charge other people to watch the movie (say in your house etc). You only bought the rights to show the movie for your personal consumption. Of course, whether or not some adverse action comes is a matter of cost to the movie rights owner vs any expected benefits. If you (or Kohl's) streamed it online then it will almost certainly be noticed and some action brought against you. But it is very unlikely that you'd be caught if you had a neighborhood movie watching party. Don't mistake "getting away with it" for "it is legal", though. | 2 |
6980q9 | Biology | Why is "no antibiotics" a big selling point for meat? | Two reasons: To keep the meat "healthy" despite the actual living conditions of the cow. No antibiotics means that the sanitation regulation for cattle handling HAVE to be followed. And second is for our own health. Antibiotics are like nukes, a last resort medication, they must not be taken so carelessly because it help with the development of microorganisms resistant to antibiotics. How do you kill a bacteria that survives our trump card? | 6 |
gk9859 | Other | What is space made out of? What is the blackness in space? | > What is space made out of? The Eli5 answer? We don't really know. General Relativity would say that it's a kind of mesh that tells matter how to move. Quantum Mechanics would mostly say that it doesn't matter; just use the known formulas to work out the probabilities of things happening. Looking at it from an Entropy standpoint might make you think that it's just a place for information. But really, we don't know. Dark energy, dark matter, and our inability to reconcile our great two theories hint that we don't have a handle on that space really is. | 16 |
8yccdw | Other | If blood is a biohazard, why are feminine hygiene products not thrown away in a more careful way? | In a hospital setting it's treated as a biohazard because there is a much higher change that the owner of the blood is infected in some way (otherwise they wouldn't be in a hospital). Also, the blood isn't treated as a biohazard for the protection of the patients, it's more for the nurses and employees. They have to come into contact with blood far, far more often and from a much wider range of individuals than a typical person does. This increases their statistical change of being infected; thus it becomes wise to put more strict and careful controls in place. | 14 |
df7075 | Biology | Whilst drinking, why does most of the flavour only come in after you stop drinking and swallow? | It’s actually a patch to fix an exploit where people were drinking, getting full benefit of the flavor and then spitting the liquid back for reuse. | 9 |
5tv3w5 | Economics | Why do we still have to file taxes? | This has nothing to do with data available today but more to do with a tax system that was developed in the 1913s, changed in 1985 and hasn't been updated since. As you can imagine, back in the day, the IRS had no idea of your life situation and if you received money outside of your day job unless it was reported to them as a wage. A lot of what was done was done over paper. With today, where everything is reported to the IRS digitally and a few seconds on their part, they can find out anything about you, they could potentially do that. But there are outside factors that can change your taxes from 1 year to the next. Donations, getting married, getting divorced, kids, gains from a death in the family, etc, can all impact your taxes that can't otherwise be seen by the IRS unless reported to them. Ideally, if your income, donations, family structure, etc. hasn't changed at all, then yes you could literally take the same tax return from the year before and re-report. The other aspect is that the IRS still uses a lot of older systems similar to most other government agencies. This can bog down their system and since there's only a handful of them and 100s of millions of U.S. adults who work, that's a lot to process. It's just easier to get those 100s of millions to send in their taxes and check to see if everything is correct vs having to generate 100s of millions of reports to people, have them check it, then send back. People are inherently lazy, so its easier to make people send in the information vs waiting to receive feedback. | 37 |
aft4gq | Biology | As babies we learn to drink from a bottle while lying down, but as adults we easily choke on a small sip of water. At what point do we lose the ability to drink while lying down? | When we’re born the parts of our throat that send food to the stomach and air to the lungs are higher up and that lets us swallow and breathe at the same time. But we can’t physically speak with it up that high. We evolved to have it drop down lower allowing us to speak. Of course we can still drink while lying on our back, but the risk of choking is higher than when we were babies. | 7 |
60vgel | Biology | How come sharks have survived from the time of dinosaurs, but other large sea creatures such as Mosasaurs and Plesiosaurs did not? | Larger things need more oxygen. There is less O2 in the ocean and the atmosphere today than there was in dinosaurs time. Therefore there is less megafauna. | 16 |
n5ubej | Biology | Why can antibiotics completely wipe out pathogenic bacteria and for the most part leave the beneficial untouched? | It doesn't, it wipes out all bacteria. This is why you are adviced to eat probiotic yogurts as those contain beneficial bacteria. | 1 |
b3yc8q | Technology | How is the internet stored? Are there people who have like a million hard drives to store all of the internet so it can be accessed wirelessly? | Here is a view of some of the underwater cables that connect various countries and then from there eventually to your local provider. So access a site in Japan from the U.S. would travel over some of these and access their drives. [ URL_0 ]( URL_0 ) | 3 |
6t7rp5 | Physics | Why can't temperature be below absolute zero? | There are some good answers here but i feel they don't go into *ELI5* territory. So I'll try: The reason temperature can't go below absolute zero is the same that the amount of water in a glass can't go below zero. You can put water in a glass and pour water out, just as you heat things up and cool them down. But once the glass is empty, there's no more water left to pour out. The same applies to temperature; when you hit absolute zero there's "no heat left" to take out. This is not intuitive because the temperature scale we use normally can go into both positive and negative numbers - because we didn't know about absolute zero when we invented it. Imagine finding a well with water in it, but you don't know how deep it is, so you just say zero is the amount that was in it when you found it. If the water level goes higher, it's positive, and if it goes lower, you say it's negative. Later, you find out how deep the well is, and thus now you know that the water can't ever go below the bottom - which is going to be some seemingly random negative number according to the system you invented. Obviously this is a **gross** **oversimplification** and **highly** **inaccurate**, but it's the most ELI5 thing I could come up with. | 3 |
nsi1wf | Earth Science | What is "fresh air"? Is air not just air? | The concept of “fresh air” is a Victorian one. The Victorians were terrified of suffocating in their houses - even though studies have shown that their houses were far more draughty than our modern houses with our well-sealed doors and double-glazing and proper waterproofing, and modern houses experience a complete change in air every thirty minutes whether we want to or not. The general medical advice in the 1800s was to always leave at least one window open (regardless of weather) to allow “fresh air” to circulate and avoid suffocation. This was especially important for children. Fresh air has maintained its reputation for health benefits, but its meaning has changed slightly over 200 years. Now, it means “air without pollution” instead of “air containing oxygen.” | 3 |
ciuh16 | Technology | how do ICBM travel such long distance in short amount of time? Can they be intercepted? | Because an ICBM is a just a rocket and rockets go really fast. Rockets that reach orbit are traveling at least 7.8 km/s. ICBMs are only a little bit short of that speed. The very first rockets that sent satellites and even humans into space were literally ICMBs but with a satellite or capsule instead of a nuclear warhead. Can they be intercepted? Technically yes, but it's really hard even under ideal circumstances. It's like trying to shoot a bullet out of the air with another bullet. | 4 |
ds2m8m | Economics | The Tulip Mania situation | Tulips became trendy and started selling for high prices. People thought the prices would keep rising so they optioned them, betting they could buy at today's price and sell later for more money. Eventually it all crashed because tulips are not a real asset backed by anything. See also: Beanie Babies. | 2 |
dvf5jk | Other | People get less embarrassed the older they get. Why? | Fitting in just matters more when you are younger, and being shy is anxiety usually related to trying to fit in Priorities change with age | 4 |
62pw01 | Biology | Why aren't there other forms of intelligent life on earth? | Why aren't there other species as fast flyers as peregrine falcon? Or other species with as strong a bite as a crocodile? Or as big as a blue whale? No matter how you rank some quality of an animal, there is going to be some animal that has the most of that quality. It'd be a ridiculous coincidence for two organisms to be exactly the same in any given respect. There is just too much variation in life. | 24 |
k2a823 | Other | In music, how come major scale is the happy and joyful while the minor one sounds sad and depressive? how does it work? | I know you asked about keys but it's even more intriguing to see that even a single chord can be sad or happy. When you pluck a string, you hear a note. If you listen closely (or use a measuring device), you can hear other notes in decreasing volume. The name of these notes (called overtones) are the fundamental (wich you hear very distinctly), the fifth (wich you can hear if you pay really super duper close attention), and the third (wich is audible with training or a measuring device) To play any chord, major or minor, you need to play three different notes at the same time, so you need three strings. All of the strings will play a fundamental and it's overtones, but remember that the only note you really hear is the fundamental. So with your three strings if you play the fundamental, the fifth, and the third at the same time, you get a major chord. If you chose A as a fundamental, you get A major. The chord A major sounds happy because the three different notes used to play the chord are already there in the fundamental, the A ! But if you play a minor chord, you have to play the fundamental, the fifht and the MINOR THIRD. The minor third is also produced as an overtone by the fundamental but less audible than the three main one. The brain hears that the notes you played are different from the overtones of the fundamental. The feeling you get when this happens is the "sadness" you refer to. | 5 |
5pws3l | Physics | how do big hotels keep their showers so hot and high pressured? Currently staying in a big hotel and had a shower thought this morning - how does their system cope with the 8am rush on hot water? Is it an upscaled version of what I have at home or is something special happening? How do they keep the pressure so good - my hotel shower is better than my amazing pressure at home! | Large buildings like hotels, high rise condos/apartments, etc have large boilers that can generate massive amounts of hot water and use pumps to supply pressure. | 4 |
hiohzw | Technology | In a recording studio, why use studio quality headphones, when most people won't be using those to listen Studio quality headphones give accurate representation of sound, but most people listening to the music won't be listening with that high quality, so they'll miss a lot, or it might sound quite different for them. | Because you want the source recording to sound as good as possible. Many people use quality speakers or headphones. Any recording is only as good as the weakest component in the chain, so you start high and then if people want to have a degraded experience that's their choice, but you don't cater to the lowest common denominator because then there is no quality version of the thing you just spent a lot of time and money to create. | 5 |
ajqvxj | Culture | Why are Americans allowed to pay bail to get out of jail? | Its important to note bail is only offered prior to conviction. It's been established that the government can't force you to stay in jail until trial unless you are judged to be a huge risk of fleeing or reoffending. (Ie the courts can't declare you "guilty" without being proven guilty) At the same time, the courts want to give you an incentive to show up for trial to make it easy for them. Requiring you to put down a reasonable sum of money, to be returned only after a successful court appearance, does that job. | 6 |
kxfxxy | Biology | how big fish can swallow other fish whole. Why can't smaller fish swim out? Can't they attack the big fish from the inside? Thanks! Edit: to all the comments saying it would suffocate and be trapped in the stomach. I get that. But when I picture the stomach I don't see it as armored or anything. It's still very soft flesh. I would assume the smaller fish would at least have a couple moments to struggle and bite before it suffocated. Even if a large fish/shark/whale was bitten from inside their stomach once or twice I W OK ukd think that would still cause issues. | There is a pic around here somewhere depicting an eel burrowing out of a flying egrets neck... -successfully- he was having none of it. Hope he at least landed in water. | 5 |
l7ckr5 | Economics | Stock Market Megathread There's a lot going on in the stock market this week and both ELI5 and Reddit in general are inundated with questions about it. This is an opportunity to ask for explanations for concepts related to the stock market. All other questions related to the stock market will be removed and users directed here. How does buying and selling stocks work? What is short selling? What is a short squeeze? What is stock manipulation? [What is a hedge fund?]( URL_0 ) What other questions about the stock market do you have? In this thread, top-level comments (direct replies to this topic) are allowed to be questions related to these topics as well as explanations. Remember to follow all other rules, and discussions unrelated to these topics will be removed. **Please refrain as much as possible from speculating on recent and current events.** By all means, talk about what has happened, but this is not the place to talk about what will happen next, speculate about whether stocks will rise or fall, whether someone broke any particular law, and what the legal ramifications will be. Explanations should be restricted to an objective look at the mechanics behind the stock market. EDIT: It should go without saying (but we'll say it anyway) that any trading you do in stocks is at your own risk. **ELI5 is not the appropriate place to ask for or provide advice on stock buy, selling, or trading.** | What are the odds GME hits its target goal of 1k per share? WSB has proven they can hold the line and buy the dip so in theory it sounds possible. | 489 |
6zzaww | Economics | People say big corporations don't pay their share in taxes by using tax loopholes. What exactly are these loopholes? | There's a great video on this by Super Bunny Hop. It's how huge videogame companies use the tax laws on two countries that create a he-said-she-said scenario on where to pay taxes. For example, a Company with its HQ in the US makes an office in Ireland. US Tax Law states that the taxes need to be paid in Ireland, while Ireland says the taxes need to be paid in the US. In the end the taxes aren't paid, and the investors get more money in their coffers. This is an oversimplification, but that's basically how ot works. | 31 |
jhaz24 | Biology | What happens in the brain when someone has a "lightbulb moment" where they suddenly understood a math concept or other concept? Did a physical change in their brain occur during this "lightbulb moment"? When you learn something new what actually happens in your brain? Is it like a new neuron grows in a certain part of the brain, or links to a different neuron? or is it something else? What about if learning something physical, does that mean the same changes happen in a different region of the brain like the cerebellum? | Until a "light bulb moment" occurring is captured in an MRI or similar scan at the moment of it's occurrence, and that is done many times with many different people to truly capture sufficient reliable and consistent data, nobody can give you a proper answer on what "happens" to / in the brain. If anybody does give you an answer, while this observed data does not yet exist, know that it is speculation, even if given by the world's best neuroscientist. That being said - the brain is known to process information not only consciously, but subconsciously as well. Namely, it is known to perform problem solving tasks in this manner. It's called Unconscious Cognition. Sudden realization moments happen likely because your brain has been working on a problem for a while, while you were unaware of it, and has either reached a solution which you then become aware of, or you have acquired some additional information that it required in order to reach that solution. Minor Addendum: *Your brain does a LOT that you are not aware of. Imagine being aware of every single aspect of every single sensory input being processed, being aware of all memory alterations or fading, being aware of all the cognitive functions involved in forming sentences or interpreting language spoken to you, being aware of all the cognitive functions involved in you reaching to grab a can of soda with your hand (the distance to reach, the amount of pressure to get a good grip, the amount of muscle tension to control the speed of your reach, even the recognition of all the visual patterns that make up the "soda can" object), etc. Your brain does a whole lot of work subconsciously, and a lot of problem solving already in most aspects of life. The same applies to cognitive efforts like solving mathematical problems, or other such endeavors.* | 3 |
cyqp7q | Economics | In Economy, why are companies condemned to "grow or die" | It's not because companies need to grow, it's because \*investors\* demand growth. That is because if your money is tied up in something that isn't growing, and some other investment is growing, then it's foolish to leave your money stuck in the no-growth asset. Sell it, and buy what's growing. This concept is referred to in economics as \[opportunity cost\]( [ URL_0 ]( URL_1 ) ). In simple terms, the cost of your purchases isn't just "minus money, plus thing", it's also "what other things could I have bought with my money". In practice, there's always a tension between a company's efforts to grow, ie: realize opportunities to make more money in the future, and to remain stable, ie: reduce risk of losing their current market position. And there's always someone around the corner looking to grow themselves, and sometimes that means they're looking to chisel away at your own market share. | 6 |
6pb5yl | Biology | what is it about the structure of vegetables that makes them so nutritious yet contain relatively few calories? | We cannot digest cellulose. That is the physical structural component of plants. Because we cannot digest it we cannot get nutritional value from it. We call it dietary fiber and it passes through our bodies mostly intact. We are able to digest other components of plants and so get many vitamins and such from them, but the sugars that make up their cellulose are locked away from us. This is perhaps the greatest proof that we are omnivores and not herbivores. | 3 |
c4iii4 | Other | In the US, when shipping commercially from the mainland to a U.S. territory (e.g. Guam, Puerto Rico, American Samoa), it's treated as if it is heading to a foreign country. Why? I'm a low level employee for an online retailer, and I ship out merchandise to U.S. Territories frequently. I noticed that shipments to them are like exports to other countries (I do those too). This doesn't seem to be the case for Hawaii and Alaska. How come? | FedEX and UPS treat shipments to U.S. territories as international because it's expensive to ship and they can collect more money that way. It's their internal system. They are not at all required to do any of that, and the USPS does not. Commercial shipments to Puerto Rico or the U.S. Virgin Islands from the states are not exports, and there are no tariffs, customs, or duties because they're part of the U.S. Legally, the only difference in shipping there as opposed to another state is that you need an Electronic Export Information (EEI) filing for merchandise worth over $2,500 because Puerto Rico has its own tax system and collects taxes on those goods. Fedex and UPS could absolutely treat shipments to U.S. territories the same way as the USPS. They just choose not to because they know they're a lot faster than USPS and people will pay more for "international" shipping that's faster than the USPS. | 1 |
iz0fjf | Technology | Why did old GPUs not need as big heatsinks? If you look at pictures of pretty old GPUs you will see that they barely had any cooling onboard. Now the best GPUs all have massive coolers and multiple fans. What made the power consumption go up so much? (Even old CPUs like a Pentium needed a big heatsink, why not the first GPUs as well?) | Because they were far less powerful. As Uncle Ben said "With great power comes a metric ass butt fuck ton of heat." I'm paraphrasing. The faster the clock, the higher the voltage, and the higher the internal capacitance, the higher the power dissipation. Die are also getting physically much larger and contain billions more transistors. Each of which dissipates a little bit of power. And the old heatsinks on processors were NOTHING compared to the triple fan 300mm liquid cooled setups most people are running now-a-days. For the same reason. An i7 or i9 running at 5gHz could boil a cup of water easily. | 3 |
kpygt5 | Chemistry | Pasta sticking in boiled water Why do the macaroni noodles stick together when I put them in the boiling water and let them sit for a few seconds instead of stirring them right away? (I assumed chemistry but not sure) | The pasta has a little bit of starch on the outside. If it hits the water in a clump the starch will soften and glue together with the starch from its neighbor. Edit Here's a source: [ URL_1 ]( URL_0 ). ### Stir your pasta. A lot. During the first two minutes that you drop your noodles into boiling water, they're covered in a sticky layer of starch. If you don't stir them continually during the first two minutes, the noodles will stick to each other and stay stuck because they'll cook adhered to one another. So just keep stirring. | 2 |
6x53ua | Biology | Why do even little kids already have a concept of human attractiveness? My nephew, who was four at the time, once told me that he didn't like my nose and thought I was ugly (joke's on him since we share some resemblance). But how come a four year old already thinks in these categories? Isn't the concept of attractiveness something that has to do with finding a suitable mate and therefore supposed to develop later in life? Edit: grammar | Attractiveness is partially due to genetics (nature), and cultural pressures (nurture). The nature part is basically looking for symmetry and 'normal'ness. Most of the rest of the things we consider attractive develop later in life. | 2 |
c2webb | Economics | What is a second mortgage for? My friend said her house is fully paid off, there is no mortgage left to pay, but she needs to take out a second mortgage to get approved for a loan or something like that. What is a second mortgage? How do they work? | It's just another loan, with your house as the collateral. If you own your home, a lot of your wealth is the home itself, which means you can't use that wealth to pay for things. A 2nd mortgage converts some of that wealth from property into cash so you can spend that wealth. | 1 |
ho0901 | Other | Why do pyjamas seem to help depressed people? | Think about all the things that you really enjoy, your favorite games, your favorite shows, hanging out with people you like, whatever gets you energized, excited, emotional, happy. Then imagine that none of them bring you joy anymore, or really any emotions at all, and nothing else does either. There's no color anymore, everything's grey. You just get up and do the bare minimum to get through the day. Often, that does not include changing out of your pajamas. Or showering, or whatever. You eat not because you like the food, even if it's your favorite, it just doesn't taste good anymore, but you need some food to cancel the pain in your stomach, so you eat it anyway even though you don't want to. That's depression. | 4 |
6kguye | Chemistry | - Why do medicines in Europe come in blister packaging and in America in small jars? | I'm not 100% sure but I'd imagine it has something to do with most European countries having centralized healthcare and already controlling the prices and quantities of medication, whereas the US pharmacies but the pills in bulk and distribute them as needed | 2 |
hr2vyy | Biology | What creates autism? | If anyone has a meta analysis supporting the "It's learned"-thesis, I'd like to see it. Afaik it's largely genetic. Research isn't sure what exactly causes the changes or even what triggers them. The theory that comes to mind regarding this would be that as a result of the wrong genes being inherited or expressed, the dendrites in your CNS are creating connections in a manner that is unusual. Changes in your nervous system can yield drastic results. The spectrum of conditions that we call autism is one of these results. | 11 |
awxghj | Economics | Why is the 1 note currency worthless in some countries. In some countries like the United States, Canada, UK, Europe one (Dollar, Pound, Euro) has value and can buy you something. While in countries like the Nordic countries, Colombia, Czech Republic, and Poland one (Krona, Zloty, Peso) is virtually worthless, and in some cases it takes thousands just to buy something small like a bag of chips. Why is that the case in these counties even though some countries with high note values have extremely strong economies? and How did these currencies end up this way? | Eh, the Polish złoty was redenominated a quarter of a century ago. You can get a beer for 2 zł. | 5 |
a9jckp | Chemistry | What about meat makes it satisfying to eat, and why is it so difficult to replicate the extent of this satisfaction in fake meat (e.g. soy)? | Everyone is talking about basic aspects like flavor, texture, etc. Even more important, I think, is the memories associated with eating meat. Every steak, every burger, brings back memories subconsciously of every other time you've had that food and the good times associated with them. Any new "fake food" had no memories like that and will have less of an endorphin release. In addition there is a stigma associated with"fake food" and so there is a social aspect as well. | 14 |
drrq2r | Biology | What allows humans to consume so many substances without incidence that are toxic to many other mammals? | Humans are great at eating a variety of foods because of our livers being super adaptable to whatever food is available. However also keep in mind there are a lot of things animals can eat that humans can't, such as raw meat from fresh kills. | 4 |
8rk9gx | Biology | Why is the bodies response to getting a cold, starting a bunch of processes that make you way more likely to spread disease? | You're thinking about it backwards. It's more that diseases which cause your body to spread them are more likely to spread.. So any disease which makes you cough and sneeze will spread and any disease that doesn't isn't likely to spread. That's the simple explanation. | 3 |
7ukwjw | Technology | Why don’t the speakers at loud concerts cause feedback in the singer’s mic? | Firstly, because there’s a sound engineer making sure it doesn’t. Mics that people sing into live at a loud venue are directional: they pick up sound way more from the direction they’re pointed. The concert speakers are positioned in front of the singer, facing outward. Before the concert, they determined how much gain (amplification) the mic gets and how loud it can be without causing feedback. Often they’re turned down to stop feedback, and in live venues have to sing pretty loud. It’s part of why album recordings sound better, among other things. In a quiet room at a quieter volume, we all sing better. | 2 |
61or2l | Other | How do Casinos Prevent Money Laundering? | The simple answer is, they don't. I worked at a Casino where a lady would come in EVERY DAY.. Literally every day. She would only play the slots. Now the slots pay out $200 anything over that requires an attendant to come and pay you out, you also get a receipt for this payout, on that receipt it states "Jackpot Winner". Now, on a cancelled credit, where you have a certain amount of money in the machine over that $200 amount, the attendant comes and returns the credit to you with the very same receipt "Jackpot Winner". So this lady would come in with $50k in her pocket, put $5000 in to a machine, roll it twice.. cash out. She did that for all $50K. She had a clean receipt from the Casino to say she was a winner every time, so if she was ever audited, there it was in black and white to cover her. I reported it to the Casino GM who didn't give a shit because they were making so much money off of her each day. | 11 |
ctfbjv | Biology | Why we need to conserve water, despite the water cycle? In talks of sustainability nowadays you'll hear stuff like how many gallons of water it takes to make a pair of jeans, or a litre of almond milk. Why is this an issue, if water cycles back to source eventually anyway? | A cycle works if you spend as much as it is replenished. If you waste too much water, you will run out of it before it is replenished. ELI5 example: imagine that you are paid with water each month. If you waste water and run out, you will have to survive until the next month without water | 4 |
hv7vbn | Physics | What is rolling thunder? As I understand thunder is the sound of the air collapsing as lightning creates the vacuum. But what is rolling thunder, that deep long continuous thunder that happens when you might not see lightning? | Fun fact about rolling thunder. A typical thunder is, obviously, loudest when you first hear it, and then the volume dies down. With a rolling thunder it sometimes (rarely) happens that the landscape is shaped a little like a satellite dish -- think small hills or formations of buildings -- which can make you hear the thunder building up to a crescendo first, and only then dying down. Essentially, what you get in a straight line is less than what you get from the sum of reflected sounds. | 5 |
epjfbc | Physics | Radiocarbon dating is based on the half-life of C14 but how are scientists so sure that the half life of any particular radio isotope doesn't change over long periods of time (hundreds of thousands to millions of years)? Is it possible that there is some threshold where you would only be able to say "it's older than X"? OK, this may be more of an explain like I'm 15. | Supernova light decay studies. Astronomers can observe supernovas at extreme distances, which also means they can observe them a various points in the past, extending back billions of years. While the light from the initial supernova blast doesn't tell us anything about radioactive decay, the supernova creates a large number of radioactive elements that have relatively short lifespans, as in minutes to months. We can observe the changing light patterns from the supernova, and measure the speed at which various radioactive elements are decaying out of that light curve. Radioactive decay rates of elements differ by element, but they all depend on the same fundamental physical constants, so a change in rate for one element would imply a change in rate of all elements. Because we can see the same decay curve at different points in history, we can establish that those physical constants are either unchanged over time, or the change is too small to be detected over billions of years. | 7 |
ck2eh1 | Biology | how low pain tolerance and high pain tolerance works | As an anaesthesiologist, I might be able to help here. The idea of 'pain tolerance' is not as simple as a describing pain pathways. As formally defined, pain is a 'subjective' experience, one that involves a physical AND emotional response to real OR potential tissue damage. The key here is that it is subjective - two people can experience the same noxious (painful) stimuli, but react to it very differently. There are physiological explanations for why nociceptive (pain) signals are amplified or diminished - I'll save you from the long winded explanations, but if you really want to look up stuff, key works 'wind up', 'gate theory of pain', 'opioid induced hyperalgesia', 'endorphins' will shed light into why and how the body is able to modify such signals. But this isn't the same as "pain tolerance". This is simply the body increasing our decreasing the transmission of pain signals. These pain signals have to be 'interpreted' by your conscious brain to become 'pain'. Put simply, think of pain as an experience. There are factors that may increase your susceptibility to having a low pain 'threshold' (psychiatric disease, chronic pain) or factors that may increase your pain threshold (the commonly used treatment methods by chronic pain physicians - distraction therapy, yoga, massage, music, physiotherapy, etc). | 25 |
atd1bw | Technology | What waves do GPS signals use and do they have to have direct line of sight as opposed to bouncing off walls and can they penetrate thin plastics? | Gps signals are sent by radio wave at 1575.42mhz and 1227.60mhz It's literally your car radio tuned up higher | 1 |
63s8om | Other | Why do gifs take so long to load despite being so short? i have slow internet, but it's usually quicker or me to open youtube and watch a minute long video that it is to wait for a gif to start playing at a watchable speed | Firstly lets take down a misconception. GIF (*Graphics Interchange Format*) is a static image protocol, much like JPEG, mostly intended for portability and compression. However, it supported more than one image in the same file. You could see each image individually or play them sequentially. If these images are different frames of a short movie, you got yourself an animation. Therefore it was never really intended to be a video format. But since it became famous for such feature and for its simplicity, some optimizations were introduced but still a far cry from proper video formats. However, video formats do demand much more resources and are found in a myriad of different algorithms and protocols, many proprietary, while GIFs were supported natively by browsers since the Netscape days. [EDIT] It's worth mentioning that, despite not being the most bandwidth/storage efficient format, GIFs were still preferred in the old Internet days due to the way they store the image. When you're downloading a GIF over a slow connection you can kind of guess what the image looks like early in the process. The image would start showing up as a very blurred version of the original that became increasingly more detailed as more data gets downloaded. If you decide that you don't need to see the final image you can abort the transfer and don't bother with the rest. | 8 |
bp8dy8 | Technology | How do websites know to go to the mobile version on your phone even when you click a desktop link but don't know how to go to the desktop version on your desktop if you click a mobile link? | When you send a request for a website, you send information about your device and what exactly you are after in the headers of a request. There is a header called "user-agent" this basically defines what device you are on. Mine for example says "Mozilla/5.0 (Linux; Android 8.1.0; SM-T580) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.157 Safari/537.36". Therefore websites know that my device is an android device, so they know to deliver the mobile version to my device. | 5 |
il0d3q | Other | what's the feeling in your chest when something hurtful registers? | Scientists aren’t really sure. Robert Emery and Jim Coan, professors of psychology at the University of Virginia, explain in Scientific American that it could be down to the anterior cingulate cortex, a region in the brain thought to regulate emotional reactions. They suggest that the anterior cingulate cortex becomes more active during stressful situations. This region is thought to stimulate the vagus nerve, which starts in the brain stem and connects to the chest and abdomen. This stimulation is thought to lead to the 'pain' we feel in our chest. | 3 |
5yfjps | Culture | Progressivism vs. Liberalism - US & International Contexts I have friends that vary in political beliefs including conservatives, liberals, libertarians, neo-liberals, progressives, socialists, etc. About a decade ago, in my experience, progressive used to be (2000-2010) the predominate term used to describe what today, many consider to be liberals. At the time, it was explained to me that Progressivism is the PC way of saying liberalism and was adopted for marketing purposes. (look at 2008 Obama/Hillary debates, Hillary said she **prefers** the word Progressive to Liberal and basically equated the two.) Lately, it has been made clear to me by Progressives in my life that they are NOT Liberals, yet many Liberals I speak to have no problem interchanging the words. Further complicating things, Socialists I speak to identify as Progressives and no Liberal I speak to identifies as a Socialist. **So please ELI5 what is the difference between a Progressive and a Liberal in the US? Is it different elsewhere in the world?** PS: I have searched for this on /r/explainlikeimfive and google and I have not found a simple explanation. **update** Wow, I don't even know where to begin, in half a day, hundreds of responses. Not sure if I have an ELI5 answer, but I feel much more informed about the subject and other perspectives. Anyone here want to write a synopsis of this post? **reminder** LI5 means **friendly, simplified and layman-accessible explanations** | In simple terms, the only real distinction here is socialist and liberal. Progressive loosely alludes to a set of goals like universal health care, income inequality, etc., but the two differ in how they believe it can be accomplished. Liberals think it can be achieved through (regulated) capitalism, socialists - ultimately - do not. Now within the liberal space you have two distinctions: liberal on the "left" and neoliberal on the right. Neoliberalism is an odd term, because in the 90s it was used largely as a pejorative for Reagan's trickle down economics, which most reputable economists agree has been responsible for the wide swing in income inequality. Of course the truth is that neoliberal politics today aren't all that different from conservatives of the Reagan era: privatization of public goods, international free trade, deregulation, etc. And this is where the dividing line between liberals and neoliberals comes in: neoliberals don't want progressive ideals. Universal health care is a public service - they don't want those. Income inequality requires a lot of regulations on both corporations and international trade - they don't want those either. The Clintons are your prototypical neo-liberals. | 22 |
hk5iru | Biology | Why does the human heart stop? What happens in the body before we die? | The heart, like every organ in the body, cannot operate without the proper blood supplying oxygen and food. The heart doesn't beat if it doesn't have a signal from the brain. It will deteriorate and stop working if the immune system doesn't protect it from harmful things. If the waste products from the cells of the heart are not removed from it, it will die. The heart can also directly suffer damage and the body's repair system must also work. So there are many reasons why the heart stops - disease affecting major organs and systems involved in breathing, circulation, digestion, waste removal, disease fighting, brain and nervous system and trauma (physical damage). The human body is a very complex thing that relies on every system to keep functioning, not simply the heart. | 1 |
cc02dq | Biology | How do STDs form/ where do the originate? Everything I’ve seen just talks about how they spread but where did they come from? | A common feature of STDs is that they’re very hard to catch and only live in limited environments. After all, a disease like measles is also an STD but because it’s SO contagious, you’re almost certain to get it in some other way. Like being in the same room as someone with measles. You’re in rooms with a lot of people all the time, so that’s a very low bar to surmount to catch the disease. But people have sex with very few people—even the most promiscuous people still only have had sex with a few thousand people in their lifetime (Wilt Chamberlain excepted). So you have this very specific, rarely occurring means of transmission. And part of the reason it’s hard to transmit is that it only survives in a small area—the genitals and/or mouth. Or body fluids. If you look at a disease like syphilis, it’s closely related to the disease yaws, which causes sores all over your body. You can catch it by a sore touching another person with a cut. So some genetic variant of yaws happened, and only survived in mucus membranes like on the genitals. Likely this happened in the Americas. Yaws already existed in the Old World, too. But the genital kind was likely from the Americas and some sailors from early European explorations brought it back with them and passed it on in Europe. Over time, diseases tend to become *less* strong because if a disease kills a person, the disease dies too. But evolution rewards things that spread and survive, not things that quickly die off. So this first new version of syphilis brought to Europe was virulent and killed a lot of people. Over time it has become less strong but still may be deadly if left untreated. Another STD we know a bit more about is HIV/AIDS. It looks like it’s a virus common to monkeys in Africa. Somewhere at the beginning of the 20th century, someone killed and cut up and ate an infected monkey. While cutting it up, they may have cut themselves and gotten some fresh blood from the monkey into their blood circulation, and they got AIDS. They spread it to some other people, who spread it further in Africa. From there it spread to the rest of the world, though it took nearly 80 years for scientists to notice. There were Europeans who got it earlier, like the earliest guy we can confirm was 1950s—a sailor whose ship visited Africa. It’s possible that monkey to human transmission occurred multiple times but it only spread more recently due to geopolitical situations. Travel exposes people to new germs. Plus at the time HIV spread to humans, that whole region of Africa was under European colonization, which was very disruptive to human culture and society there. Families were wrenched apart. For example, men might be forced to go far away for work and congregate in heavily populated areas without families, and promiscuity flourished in that environment, which encourages the spread of disease. | 4 |
5sh7zy | Other | Why is Canada and other Commonwealth countries considered independent yet it's still under Britain's sovereignty? The title doesn't really say anything but why does UK still have an influence over an independent country? I've never really learned this during highschool and I honestly don't know why. Most of my mates doesn't even know that we actually have an actually living monarchy (or are a part of) Unlike the U.S. (which became a fully sovereign state after seceding from the Union and the Civil war) why won't Canada do the same? 1st world countries such as Australia and NZ is also part of the Commonwealth and I honestly have no clue the reason why. Why do we have a queen that's thousands of miles away from us, and why do people say that she owns most of our land? How powerful is her influence? I know that we have a long history with Britain but IMO monarchial governments are outdated. First and second generation of Canadians that came from other countries aside UK doesn't seem to fully understand or accept the fact that we have another head of state aside from the Prime Minister. I just don't understand. Edit: I wrote this while I'm in the subway. The format is terrible I'm sorry | While the countries you mention have the British monarch as their sovereign, these countries are, for every practical purpose, completely independent from the UK. And yes, in Canada and other commonwealth countries, the PM is not the head of state -- the PM is the head of government, and the Queen is the head of state, represented in the country by a governor-general. Why won't Canada do what the US did? Because it doesn't need to. The states that formed the US would have been *absolutely delighted* to get a deal like Canada and the rest of the Commonwealth has now. And the right to govern their own internal affairs was exactly what the colonies were asking for, and what they went to war over. Basically, the Commonwealth nations were able to maintain their cultural ties to Britain yet have independence in every single way that is important. And really, this was possible because the US showed that it was possible to break away. | 2 |
6okby3 | Other | How jurors on long cases maintain a job and a steady income while the case goes on? I'm currently watching the O.J. Simpson case and in it they talk about the jurors being "locked up" in a hotel for ~280 days. How do they maintain a job or get a money? | It also depends on your employer. I worked for a company that just paid you normally while you were on a jury. I'm not sure what they would have done with a 280 day trial, but I know of a guy who got paid normally for a week long trial, PLUS he got the money the state paid jurors. | 5 |
dotqvy | Physics | Why can’t a spaceship in orbit slow down beneath e.g the speed of sound, to fly down to earth like a normal plane? When entering the atmosphere, spaceships are so fast that they need a heat shield to not burn up. Wouldn’t it be easier when they just fly down like a „normal“ airplane? | If you are in orbit, the ISS moves at 5 miles/sec, and you start slowing down, the Earth's gravity starts to pull you down. You have to get down to .21 miles/sec to get below the sound barrier. That means using rockets or something like that to remove 24/25^ths of your speed. During that time you'll start to go down pretty fast, so you'll need more rockets to offset that acceleration. Then you can start "flying". This is much, much more difficult/expensive than the current schemes. | 6 |
nr9inn | Physics | If a thundercloud contains over 1 million tons of water before it falls, how does this sheer amount of weight remain suspended in the air, seemingly defying gravity? | All the discussions about suspension of water in air and resistance to falling because small particles are slow to fall, and all that, are part of the story. The real, or most important, reason is that the amount of volume that holds such a large mass of liquid water is enormous, so even though the amount of water in unit volume is actually quite low even in thunderstorm clouds (several grams per cubic meter as a general idea is a pretty good estimate of water content in thunderstorm clouds), when there is a huge volume involved, the masses get huge too. Most of the cloud is not water but thunderstorms are huge: many kilometers high and covering many tens of square km of horizontal area. this means that the thunderstorm is on the order of maybe 100 cubic km in volume (10 square km area by 10 km high=100 cubic km) or a lot more perhaps. Well, 1 cubic kilometer is 1 BILLION (thousand million) cubic meters, so a single cubic kilometer of cloud would have about 5 billion grams of water, or five million kg, or 5,000 tonnes (metric tonne is 2250 pounds, about). Expand that to include all of that 100 cubic km cloud we just mentioned above, and the total amount of liquid water would be 100x5000 tons, or 500,000 tons. Make the storm a bit bigger or the water content a bit higher, and you get to 1 million tonnes. It is a lot of water, definitely, but the volume is really big. So the "real" reason is simply that thunderstorms are really big so there is a lot of water in total. The real fun thing is that the weight of the air in that same volume is way higher than that million tonnes of water. Air is on the order of 1kg per cubic meter (depending on how high you are; about 1.2 kg per cubic meter down here at earth surface). You didn't ask why the air doesn't fall even though it has way more mass. | 8 |
kh9wes | Other | How do "rehabilitation over punishment" countries deter crime, when prison seems like an improvement over standard living conditions? | The US has a culture of incarceration, which basically means "put them in jail" as a method of controlling crime, even including minor offenses. But this doesn't deal with the causes of crime, it actually just makes the problems worse. Having a criminal conviction makes it that much harder to be successful in life, so being put in jail for something as trivial as marijuana use can significantly curb your opportunities in life. So a lot of criminals get institutionalized where putting them in jail just makes them worse criminals when they get out. Meanwhile the murder rate in the US is more than 18 times higher than Germany and the UK. Some people are criminals because they are crazy, you can't really stop that. You can only identify them early enough to either treat them or make sure they aren't a danger to anyone else. Most crime though is a result of social conditions and poverty. Having good social structures in place like affordable education, healthcare, and childcare makes a really big difference particularly to the most vulnerable populations like the working poor. The US has the least effective social net in the Western World stemming from various factors including decades of anti-communist propaganda stopping social programs from being implemented. Combine that with extremely lax rules on Guns, systemic racism, militarized police forces, poor mental health care, and wide spread gang warfare and you get the problems in the US. Locking people up en-mass and waging a war on Drugs has been a complete failure. So as a result things like Gang warfare and Drug related crimes are really high. | 3 |
k44ugj | Technology | Who actually launches the rocket, mission control or the astronauts aboard the rocket? | In most cases, it's either the rocket itself or a computer in mission control. There's a control computer that's doing all the sequencing of major actions and checks. The astronauts and mission control have lots of ways of \*stopping\* the launch (as does the control computer itself), and there will be a few key decision points where the astronauts or mission control have to provide an affimative "go", but the actual launch (like, release the claps and fly) is sequenced by computers that will execute unless told not to. | 4 |
8kf5by | Technology | How did AutoCAD become the industry standard for drafting when it is horrendously buggy and prone to crashing? I’ve used a lot of post-2010 versions of AutoCAD over the years in a variety of offices and at home. It’s the buggiest program I’ve ever used by far. Even sometimes something simple like editing a text box makes the whole program crash to desktop. Looking around on the Autodesk website and other forums shows me this is well known about AutoCAD. How did it become the standard over other CAD programs despite this huge cost in productivity? | Is this even true? I think it greatly depends on the industry. In the aerospace industry CATIA from Dassault is far more standard than AutoCAD for example. | 7 |
id9brq | Physics | Why does something soaked in water appear darker than it's dry counterpart. It just occurred to me yesterday, other than maybe "wet things absorb more light" that I really have no idea. Just a few examples: - Sweat patches on a grey t-shirt are dark grey. - Rain on the road, or bricks end up a darker colour. - (one that made me think of this) my old suede trainers which now appear lighter and washed out, look nearly new again once wet, causing the colour goes dark. | I am not sure if this is allowed, but after reading the other answers, and great they are; it got me curious, so I Googled it and found [this]( URL_0 ) amazing article. I’ll paste it below. If this is against the rules I’ll remove it. The speeds of light We think of light as waves that travel in straight lines at a constant speed — 300,000 kilometres per second. But that's only true for light travelling in a vacuum, like empty space. Whenever light has to travel through anything with actual molecules floating around in it — like air, water or fabric — it slows down. The slowing down happens because whenever light bumps into an atom or molecule, it gets absorbed and spat out on the other side. And all that absorbing and spitting takes a tiny fraction of time, so the light passes through any material more slowly than it would through empty space. Air doesn't have too many molecules to bump into, so it only slows light down a tiny bit (0.03 per cent). But water has way more molecules than the same volume of air, so light really has to work the room when it goes through the wet stuff — it's 25 per cent slower in water than it is in space. And fabric is even more dense than water, so light slows down by a massive 33 per cent travelling through your t-shirt. The speed of light through a material compared to its speed in a vacuum is called its refractive index. The refractive index of empty space is 1, and air is 1.0003. Water has a refractive index of 1.33, and fabrics are all about 1.53. But it's not the speed that light's travelling through water, fabric or air that makes wet things look darker — it's what happens when light changes speed that does the trick. And light changes speed whenever it moves from one refractive index to another. If a beam of light moves from air into fabric, it has to slow down from 300,000 kilometres per hour to 225,000 kilometres per hour instantly. And putting on the brakes like that makes light do the equivalent of an electromagnetic skid. It bends. Light gets the bends Why things look darker when wet The bigger the change in refractive index when light moves from one medium to another, the bigger the change in speed, and the bigger the angle that light bends at. So when light passes from air into fabric it bends at a much bigger angle than when it goes from water into fabric. And light doesn't just bend once when it goes from, say, air into fabric. Clothes are made up of fibres and air. Light passing through a t-shirt is going to constantly move in and out of the fibres and the air, and it bends every time it does. Because the refractive indexes of air and cotton are so different, the angle of the bend is pretty big. All those big angles mean that a lot of light ends up bouncing back out of the fabric — and some of it will head straight for your eyes. When your clothes are wet, all those air gaps get filled with water. So when light hits a wet patch it's moving in and out of water and fibres, not air and fibres. The refractive index of fabric is a lot closer to that of water than it is to air, so the light doesn't change speed quite as dramatically going between water and fibres. And that means it bends at a smaller angle when it goes from one to the other. It's those small angles that are behind the darkness of the wet spot. With small angles, it takes a lot more bends for light to turn right around and head back out to our eyes, so more of the light ends up travelling forward into the fabric. And that patch looks darker. Spend a few minutes under a hand dryer or sunshine, and you'll see the t-shirt lighten up again. As the water evaporates, air comes back into the water/fibre mix, and brings some bigger angles to the light, so more of it makes it back to our eyes. And we can face the world with crisp dry confidence again | 9 |
apsl4f | Technology | We get Internet from ISP. From where does ISP get Internet and how? | The answer given by /u/nmbgeek is mostly correct (and would have been completely correct 4-8 years ago). Today with the emergence of IXPs (Internet eXchange Points) even the smaller ISP's are getting on on settlement-free peering (not having to pay for all of their traffic) Let's take this from the perspective of a smaller regional ISP (which would have been a Tier3.) We serve around 8000 homes and use ~15Gbps of 'Internet'. Being in the middle of nowhere, we have very limited local options to get our Internet from. So we buy some access from a larger regional Tier 2 on our border just as in /u/nmbgeek's example (which is mostly only used if our other connection detailed below has an issue as a backup). We also lease a dark fiber (a fiber cable with nothing on it that a different company owns, and allows us to put whatever we want at each end) that gets us connected into a major IXP, this could be 100's of miles away. Once we are connected to this IXP we have two connections, one that is paid directly to a 'Tier 1' provider, but more importantly a connection on the 'exchange'. Once on the exchange we can set up 'peering agreements' with all of the major sources of traffic, Netflix, Google (YouTube), Amazon, Steam Etc. that allows them to send us traffic directly at no cost (other than getting to, and onto the exchange) since they also get to have that traffic bypass their ISP to get to us. Since most of the traffic comes from sources that allow this peering, we can get away with about 60-80% of our traffic coming from the exchange. | 10 |
iiedpk | Other | What checks are actually done at a store (not a gun show) when you purchase a gun in the US? | does he have a concealed carry permit? Those allow much, much faster transactions. The checks are all the same regardless of the myth of gun shows. Some people are already on file if they purchase firearms often. Their info is ran against a database for criminals and if there is something that prohibited them from firearms. Some system are faster and it also varies by state as well. | 2 |
8us1c6 | Technology | Why is one of the FCC regulations: "A device must accept any interference received, including interference that may cause undesired operation" | Best explanation I've found came from here [ URL_0 ]( URL_1 ) Basically the device must be able to handle interference from other devices, even if the interference is strong enough to cause it to start malfunctioning, without causing any serious/dangerous failures. For example, small interference (which probably happens everywhere) will have no effect on your TV due to the case, interior shielding, etc. Stronger interference might cause the picture to start screwing up. It shouldn't blow up though... | 2 |
7l4w1o | Other | Is over-population a self managing problem, or at some point are we going to have to intervene? | Long term it is a self managing problem. Unfortunately, the "management" is mass starvation and wide-spread disease resulting in the death of billions, followed by the crumbling of civilization and a reversion to hunter-gatherer tribes. So we might want to intervene before we get there. | 1 |
8ywcda | Biology | I have a friend who believes Amygdalin (sometimes marketed as "Vitamin B17") is a cure for cancer. Thankfully, he is open-minded and responded well to my criticism. Please, explain how B17 is (or definitely isn't) a cure for cancer. | > explain how B17 […] isn't a cure for cancer. I mean, there's not a lot to explain. It doesn't cure cancer. No studies have ever supported that it cures cancer or show that it has any effect on cancer at all. Its primary effect is to potentially cause cyanide poisoning. It is not a vitamin for the human body. The only way it would stop cancer is by killing someone. Pretty much the only evidence in its favor is that someone said "Well this doesn't seem *too* poisonous, maybe it cures cancer!" | 2 |
c1h80h | Biology | Why can't you take medication to get rid of plantar warts like any other virus? | Because most viruses aren't curable with medication. They can treat symptoms, but not cure. | 3 |
elfu5w | Biology | The skin's cells are regenerated every 27 days, and the entire body's cells regenerated every 7 to 10 years. If this is the case, how do skin imperfections like freckles, scars, and birthmarks persist? | For the same reason you can't regrow a limb. Just because cells die and are replaced doesn't mean those replaced cells return to their "original" position pre injury. Cells divide remember. There isn't a cell factory in your chest that makes all the cells and sends them out to where they are needed and puts them in the right place. What was there (scar cell) divides and makes additional scar cell. Here's a mental experiment. Let's say that you have a plate with a bunch of sand on it. And magically each grain of sand is replaced every 5 minutes. If you clump all the sand into two piles. The sand doesn't flatten back out into a flat disk as the individual granuals of sand are replaced. Instead they piles remain the same and the new sand takes the same position as the old sand. This is how a scar works. Your body made the scar on purpose. Scar colligen and tissue aren't accidents. They are ways your body deals with large wounds. Once the scar is in place. Those outgoing structures are replaced with. More of the same structure In the same place. | 2 |
6t8kao | Other | If the gov't can take real property through eminent domain for the public good, why can't it take things life saving medications that would be in the public good? | If you were a company and you spent 500 million developing a drug and the government took it from you preventing you from making your money back you would go put of business from debt. If you saw that happening would you start a business knowing that the government could intentionally destroy your entire life work]? | 5 |