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gtsxq7 | Other | What is anarchism? I just got into history and I was watching a video where the guy started taking about anarchism. I have no idea what this word even means (I'm not a native English speaker). Can anyone explain this to me? | It generally means that the person believes that there should be no government or organizations such as police, Army etc and instead the people should be able to operate without rules or oversight. It can be mixed with other philosophies since it really only concerns itself with the relationship of the individual to an authority. For example, you can be an anarcho-communist who believes that we should not have a state who is the authority but that it's beneficial to share resources with each other. | 2 |
6686cq | Culture | How did baby boomers when they were young manage to pay for a house and raise a family while on single incomes (the dad working), yet today young couples can't even afford a small home and struggle to raise even one child while there's two incomes (mom and dad working)? What happened? | I am URL_0 Dad couldn't. He worked full time for the phone company and had his own floor sanding business on the side. He worked 8 hours for telco, the went straight to work for work at his business weeknights another 6 to 8 hours. Weekends he worked Saturdays, sometimes Sundays. He did it for years to buy a house for us. In the 80's I was in the Air Force, worked my 8 hours , as a telephone tech. We worked like a civilian company, Mon thru Friday, nights weekends and holidays off. It was awesome. No shift work. Me and 6 other techs worked full time for a civilian telco at night , running cable, terminating and testing them, 6 to 7 hours 5 nights a week. I was married and even with the extra money we got for living off base, lower ranks could not live on base, we could not make ends meet, wife worked as well. I also worked a 2nd full time job after I got out and worked for a telco company and did so for a few years. It always has been rough starting out in any career, it has never been unusual for people to do this, even baby boomers. Not sure why everyone thinks it was easier then, sure ,cost of living was less but so was income. | 76 |
8aduvl | Economics | What is an annuity and how is it different from an IRA? Not that I'm sure that I fully understand an IRA, but an annuity wasn't described much differently than the IRA. Is it similar, but will function more like an allowance as soon as you can use it? | They're totally different things. It's like asking what's the difference between a bulldozer and a windmill. An IRA is a special kind of account you can have with a bank or brokerage, where you don't pay taxes (way oversimplified) on the interest or profit, but you're not allowed to take any money out (exceptions apply) until you retire. Like, you have an IRA with Vanguard, and every year for twenty years you deposit $5,000. You use that money to buy and sell stocks, with all the proceeds from sales staying in the account. At the end of the twenty years, you've deposited $1M, but the account is worth $2M. Then, depending on what kind of IRA you had, you can either take money out without paying taxes at all, or having delayed paying taxes until your retirement (this is a better deal than it sounds like, okay?). tl;dr: an IRA is a kind of tax shelter that you're allowed to use, as long as you commit to using it to save for retirement. An annuity is a contract with an insurance company. You're about to retire, and you want to make sure you have an income for the rest of your life. You have $3M saved up (or, you could sell your various investments for $3M), and you could live anywhere from five to thirty more years. How much money can you take out of your savings and spend, each year, and still be sure you won't run out until you die? What if the stock market tanks? What if you live to be 115? The insurance company is willing to handle all that for you. In exchange for the $3M upfront, they'll promise to pay you $15k a month for the rest of your life. They'll take away all the risk, in exchange for you getting less money than you would (probably, but you never know) have been able to earn, managing your investments yourself. | 1 |
l2vyqc | Physics | Why is it harder to cook rice or pasta on higher altitudes? | Because the water's not as hot. There's less air pressure at high elevation, which means the boiling point of water is lower— so even if you get a pot of water as hot as possible, it's only 204°, instead of 212° (F). It's not a *huge* difference, but it's there. | 2 |
nyu9ca | Biology | what determines if a food makes you feel full or not? If I eat yoghurt or oatmeal I’ll usually still be hungry but let’s say I eat a pizza, a burger or a steak, I’ll feel full. What determines this? | Protein, fat, and fiber take longer to digest. Drop a cracker (carbs) in a glass of water and watch it disintegrate. Now drop a bite-sized piece of steak in there and watch it just sit there. Stomach acid is more powerful than water, but the concept is similar. That harder to digest food will keep you feeling full longer. Low carb foods also don’t create an insulin spike (the crash is really the problem, but you can’t have a crash if you don’t have the spike), so hunger is more gradual than sudden, so you don’t notice it as much. | 3 |
5o2bw3 | Mathematics | What does "±" symbol mean? | It basically means "plus or minus". In this context, it looks like they're using it to mean "approximately" as in "give or take a couple years". Under more typical circumstances though, it would be used to indicate a range. For example, if it said 16±2 years, then it could mean anywhere between 14 and 18 years of education (ranging from 16-2 to 16+2 years). In sciences, the symbol is frequently used to express tolerance or statistical margins of error in measurements (i.e. indicating a range of possible values). In mathematics, it can indicate that a value may result from either an addition or subtraction operation, or that a given value can be either positive or negative. | 1 |
8l44z0 | Culture | What happens when you renew wedding vows? I saw this happening in a TV show and I have neither seen nor heard this thing happening. What does it mean to renew vows? | It doesn't actually mean anything, legally. It's just something that people who have been married for a while sometimes do in order to reaffirm their love and commitment and \(usually\) throw a nice party for friends and family. They usually sort of re\-create a wedding atmosphere and it ends up being a fun, romantic way to celebrate an anniversary. But it's not a legal contract like a marriage is, no forms are being signed, no licenses required, and it's not required by the government, by a religion, or whatever. It's just a good excuse for a couple to reaffirm their partnership and celebrate. | 4 |
ckycyt | Other | Why does hot water make pasta softer? What makes hot water better than cold water? | Pasta is a porous material, hot water makes the pores dilate so that they allow the water in making the pasta larger and softer. Larger because the final volume of the pasta will be pasta+absorbed water. Cold water wouldn't dialte the pores so probably it could make the pasta softer but it would take a really long time like several days. | 1 |
5mmbwo | Culture | Why do people brag about things that are more appropriately classified as complaints? Example 1: Facebook posts about it being 13F without a wind chill followed by a complaint. Example 2: "I worked 94 hours last week!" followed by some comment about how tough life is, but in a proud tone. This kind of thing never made sense to me. It's one thing to make a complaint, but so often that complaint comes in the form of bragging. Why do we do this? There must be deeper reasoning for this explained by social science. | I'm going to go with Nietzsche on this one. He describes the phenomenon of ressentiment, in which one justifies one's own weaknesses by identifying the source of envy as objectively inferior. It is somewhat similar to the idea of "sour grapes." A person has a problem, so they redefine their value system to describe their problem as being a strength rather than a liability. By claiming that their suffering had value and they are proud of their suffering, they get to claim a moral victory. This allows them to avoid the angst and frustration of admitting that their condition just plain sucks. | 2 |
le1fb8 | Chemistry | . Chemical plants built by rivers: why? | Ready availability of cooling water. A lot of the processes inside a typical chemical plant generate a lot of heat and they have to get rid of that somehow. | 5 |
69yf86 | Repost | How does the weight exit your body when you're losing weight? | Some of it leaves in your breath. You breathe in oxygen and exhale carbon dioxide. Other amounts leave your body as other waste material, urine and poop, or as sweat. | 5 |
fn05i0 | Mathematics | [AMA] Mathematics Welcome to ELI5’s first “Ask Me Anything!” We’re inviting expert educators to respond to your questions here on ELI5. Today the topic will be mathematics, brought to you by University of Oxford maths professor Tom Crawford (u/tomrocksmaths). Dr. Crawford has asked us to share [his video about exponential growth, and why it’s so important to take every step to slow the spread of COVID-19]( URL_0 ), and [another video about the SIR model for epidemics]( URL_2 ). This thread is your opportunity to ask questions about mathematics and the teaching of mathematics. Please remember that we will still be enforcing the rules, especially Rule 1. In this case, Rule 3 is amended: top level comments are reserved for questions. We ask that you guys try to stay on topic for Dr. Crawford - keep in mind that although Dr. Crawford may be discussing how diseases spread, this is **not** a topic about the ongoing coronavirus pandemic. And a big thanks to Dr. Crawford for helping us. Check out his YouTube channel, [Tom Rocks Maths]( URL_1 )! **EDIT:** Well, I think this went very well. Thanks everyone for helping us make this a successful first AMA! Dr. Crawford is on UK time so he may or may not continue to answer questions. Next Sunday we'll be doing another AMA. This time the subject will be biology, and it will be hosted by some verified high school biology teachers! | Which field of mathematics, equation haunted you mostly, make you confused or seems unanswered now and then? Thanks | 8 |
fav151 | Other | A dark towel is hanging over a glass door so that you can see the towel through the glass. Your reflection shows on the glass in front of the towel but not on the glass with no towel behind it. What is happening to allow this to occur. | Some light is always reflecting off of the glass on your side. Normally, more light is passing through glass from the other side than is being reflected back from yours, which overwhelms the reflected light and prevents you from being aware of your reflection. When the towel is hung on the far side, it acts as a barrier to the light on that side. Now, the majority of visible light from the glass is the light reflecting off the glass on your side, allowing you to see your own reflection. | 3 |
73yzyz | Biology | Why does touching my face a lot cause pimples but the rest of my body isn't affected the same way? | Number of sweat glands, oil glands, and general sensitivity. Skin on your face is a lot more sensitive than your arms or back for example. | 2 |
gq3v5f | Biology | why does it take > 24 hours to "feel" a hard workout? | Micro tears in your muscle fibers is definitely the best explanation for soreness. Lactic acid is what causes the burning feeling when your muscles just can’t take anymore during a workout. To answer your question of why it can be delayed like DOMS (delayed onset muscle soreness) which someone has already mentioned I don’t know why it’s so delayed. I do know that it’s more delayed for those who haven’t exercised those muscles in a long time. Perhaps the inflammatory process is responsible for it though | 7 |
70iimp | Repost | If the main goal of our brain is survival, why does it let get depressed and in some cases commit suicide? | That is assuming the brain is functioning at the level it is capable of, however, when someone commits suicide they are not functioning properly mentally. Basically, you're assuming rationality in our brains goals but we are irrational beings. | 33 |
6ktgjx | Other | Why does it happen that we tend to remember some words not by their meaning, but by the context they were used in? more often than not, this is exactly the thing I have done when I want to recall certain words. I am able to remember a word by the context where it was used, but not by its actual meaning. PS English is my second language. | That's how you naturally learn language. The meaning of many words aren't particularly helpful because to understand the meaning you need to have sufficient past context Let's take sit as an example. What's the meaning of "to sit"? > to rest on the buttocks or haunches sit in a chair —often used with down That's pretty hard to explain to someone who may not know many of those words, but if you're told "sit!" and they point to a chair, you can understand what they mean even if you don't know that "sit!" is the imperative form of to sit simply because you understand context from the chair. This is how children first learn languages | 1 |
7eim6w | Culture | Why anchors from way back (30s, 40s, 50s...) sound so different from today’s anchors? | That accent (Mid-Atlantic/Transatlantic Accent) was cultivated in the industry. It has since fallen out of style. | 4 |
b9j3jh | Other | Why does our language nowadays seem so much more informal? Sparked by a TIL post, where it talked about finding the first “your mom” joke: “...of your mother is by the one who has intercourse with her. What/who is it?” Obviously, nobody would say it like this in 2019. But why? | Language has actually always had both a formal and informal element. But historically it was only the "rich" who could actually afford a good enough education to learn how to read and write - peasants / the working class didn't have the time or desire to extend their education that far. Some cultures actually took it one step further and actively prevented the lower classes from learning how to read and write. & #x200B; Paper, etc required to write things down also used to be both rare and expensive meaning that it took extra effort to actually record something in writing. Especially before the invention of the printing press. & #x200B; This has created a bias in recorded history meaning that what was written down was mainly only ever the formal version and informal language was only ever passed down by mouth. & #x200B; In the modern world though most people now have access to a basic enough education to know how to read and write and it's very easy to keep a record of stuff so everything can be written down. Informal language is easier to use so is more popular meaning that just by weight of numbers there's more informal language being used and recorded than formal style writing. | 2 |
ghljpr | Biology | Is overpopulation actually a problem for Earth and if it is, how is it a problem? | Do we have enough resources to support a population of this size sustainably? Most likely yes Is overpopulation still a problem? Most likely yes. This is because in a utopian society where humans are good to eachother instead of greedmongering hoarders then yes we have the resources to live suatainably on our planet. But we dont treat things that way. Instead we pollute, promote over consumption which leads to more waste and rapidly reduces the availability for under privelaged or less fortunate people. | 2 |
klrpoh | Physics | Since the universe and stars are constantly moving, how come we see the same stars in the night sky for millennia? | 1) We don't. [This article]( URL_0 ) goes into more detail about how constellations have changed over human history. The point is, you're right, the stars *are* moving and they *do* change. Some stars even appear or disappear as they are formed, explode, and die. They just don't change very much. 2) Space is *big*. You just won't believe how vastly, hugely, mind-bogglingly big it is. Even moving hundreds of thousands of miles per hour relative to Earth they aren't going very far, in the grand scheme of things. It's kind of like how a jet can be going hundreds of miles per hour above you but it doesn't look like it's going very fast because it's very far away from you and it's traveling a long distance. Similarly, although stars can be going very fast indeed, the distances are *immense*. Over the short timeline of a human life, human generation, even the lifetime of the entire human species' existence, the stars just haven't gone very far relative to each other. And that's ignoring that some of that movement will be towards or away from us, which won't make them shift in their constellations. | 5 |
7vkar9 | Biology | That sharp pain in your neck followed by a burning feeling after a wrong move with your head. | Oh god that sure hurts like HELL!! I used to get that a lot as a kid-- and when it happened I wouldn't be able to move my neck for a bit. It doesn't happen so much anymore. Thank goodness. | 10 |
dfahok | Biology | Why do our voices change as we get elderly? What causes the gravelyness in old people's voices? Is it inevitable? | Vocal cords are basically folded-up bits of squishy mucous membrane that bang against each other. Air moves through these folds. When the folds move, that changes the way the air that flows through them moves, which causes vibrations, which causes sounds. What the vibrations sound like depends both on the movement of the folds and on the size and shape of the folds themselves (bigger folds tend to cause lower pitched sounds, which is why our voices deepen as we get older and why men tend to have deeper voices than women). Picture a drum. You bang on the head of the drum to produce sounds. A bigger drum sounds deeper (ex: a bass drum), while a smaller drum sounds higher (ex: a snare drum). You can also change how the drum sounds by tightening or loosening the head of the drum. When we get older, the composition of the tissues changes. Parts of it get thinner and more fragile, and parts of it become thicker, and the muscles controlling it atrophies and becomes weaker. This is not only true of the vocal folds: all our tissues undergo a similar change. Picture the same drum again, but now imagine it covered in a thick blanket, or loosening the head of the drum so much that it sags. Consider how that would change the sound the drum makes. It would probably sound duller or quieter. That's what happens when we age. | 1 |
b56ta5 | Psychology | What is the science behind shy bladders? | The short answer is: we don't know. Embarrassing incidents (teasing, accidents, scolding, etc) may be a psychological cause but it is not the cause of all cases so it's hard to pinpoint psychological or physiological causes, and it can develop at any age. (I had no problem using urinals with others present until my mid-20s and now have to use a stall - and even that sometimes doesn't work if I can hear people out there. Even at home, when i had a roommate, I'd be unable to pee if i could hear them in the kitchen.) The longer answer is: our culture treats urination as a private act, but public restrooms (especially urinals) disrupt privacy. Our bodies are very good at holding it back even when we really need to go - think of how you can have a painful bladder and strong urge to go but can still manage to get home first but then it becomes harder to hold the closer you get to the bathroom. So unless you feel properly relaxed, your body can hold on. | 1 |
a8g2mx | Biology | How does a human manage to die if they slit open their wrists but doesn’t when they lose their whole arm? | Your question boils down to intent. The person who slits their wrists (in some, but not all cases) is intent on killing themselves. The person who has their arm severed often takes immediate steps to mitigate the bleeding. Left untreated, either case is likely to cause death, but generally only one is done as a deliberate act. | 3 |
akr3jj | Biology | Why does your nose get more runny in cold weather compared to normal conditions? | You are hot and wet on the inside. The air you exhale has a lot of water in it. Normally, that water stays evaporated. When it's cold outside, the water in the air you exhale starts to condense back down into liquid. This is why you can see "steam" when you exhale in the cold. Your nose holes are a bit less hot than the inside of your body because they are close to the outside air. If it's cold enough outside, your nose holes can cool down enough to let that exhaled water condense inside the nose rather. This makes your nose have water in it, which eventually runs out. | 4 |
lxckzi | Biology | If you fall asleep at 8pm and wake up at 4am with 8 hours of sleep why do you feel extremely tired by 10am, but if you go to sleep at 11pm and wake up at 7am you can stay up all day without feeling very sluggish? Does it have something to do with waking up while it's still dark? | This most definitely isn't something universal? I go to bed around 8-9 and get up at 4 every day, and I'm never tired at 10am. | 3 |
8ag1mj | Biology | What happens when we choke on liquid substances such as water? | I believe it’s the epiglottis that helps navigate and direct which things are supposed to go down which tube. It’s like a flap that opens one of the tubes, so when you get water down the wrong tube it slipped past your epiglottis. | 3 |
iso56y | Economics | Why Can’t the worlds Billionaires feed poor countries? | The money cost of "solving world hunger" is quite low. The political complications are high. Most starvation in the world is caused by things like wars and other political conflicts. Getting the food to the people who need it is the problem, not buying it. That means the billionaires would either need to bribe warlords (counterproductive) or get their own private militaries (expensive, and also probably not something you want to happen) | 3 |
5zjth7 | Technology | Why do batteries put in the freezer last longer, but my phone battery drains faster in cold weather? First, are these assumptions correct? I've heard both, somewhat anecdotally, so I'm wondering about the interaction between batteries/electronics in general and temperature. Thanks! | First, understand that you're probably talking about different kinds of batteries. "Regular" batteries are probably alkaline batteries. Your phone has a rechargeable battery and that's probably a lithium-ion one. Those batteries use different chemical reactions, so it's not surprising they react differently to different conditions (including cold). Now, that said, alkaline batteries *do* self-discharge *slightly* slower in the cold, but that degree is minuscule and not worth the effort of cooling them. Where that came from is that alkaline batteries discharge *much* faster in high heat. So as long as you don't store them in the oven, you're fine. LiIon batteries *are* more sensitive to cold, but again, as long as you're in the normal range of Human temperature tolerance, you're fine. Just don't store your *phone* in the freezer. And if you live in Minnesota, try to keep your phone in an inside pocket. Basically, you don't have to go out of your way for your batteries. | 2 |
6csgdc | Biology | Why is our own blood an irritant to our stomach? Sorry to get a little graphic but I just had a bloody nose and someone advised me to put my head back (bad idea) tl:dr I swallowed a lot of blood and vomiting and diarrhea ensued. My nurse friend said that blood is simply and irritant to our GI tract so I started wondering why? Does it have to do with the PH or.. saltiness? Any reply is appreciated | I'm not sure, but white blood cells and antibodies in your plasma might attack the natural flora/bacteria, causing your gastric system to get irritated. | 1 |
jq3g5z | Engineering | Why can’t airplanes get into space? | Airplanes, by definition, require air to work. They generate lift from the motion of air passing over their wings. Propellers and jet engines also need air to generate forward thrust, for more or less the same reason. There is no air in space. An airplane could get you quite high, but it cannot take you into space any more than a submarine can travel above the surface of the ocean. It's not actually that hard to get to the edge of space. The space program uses rockets not so much for the going-up part, but because to get into orbit (or to leave the Earth entirely) you need to go sideways really really fast. | 7 |
7q23lx | Chemistry | Why does some tap water have so many small air bubbles that it looks like its actually white? | As MarkHFX said, the bubbles are caused by an aerator. I think this is normally for efficiency; the nice wide flow of water allows you to wet your hands easily, but the bubble mixture means that the total amount of water flow is still not too high. | 3 |
csg6rr | Physics | What is the Yang-Mills millennium problem? | In Quantum Physics, particles sometimes behave as points, with a definite position, and other times spread out like waves. There are a number of theories around this phenomenon, including one named Yang-Mills. The problem with Yang-Mills is something called the "mass gap". In classical theory, Y-M predicts particles that have no mass and long-range forces. The quantum theory of Y-M needs to match the real world, with short range forces and massive (as in having mass, not huge) particles. In order to work out the quantum theory for Y-M, we basically need a new kind of math. We have some approximations and simplifications, but it's kind of like knowing the simple form of the Pythagorean Theorem (a^(2) \+ b^(2) = c^(2)) without knowing Trigonometry. It's great if all we have is right triangles, but once we get outside that, we don't have the fundamental equations or knowledge of Sine, Cosine and Tangent to work out the general cases. The Y-M Millennium problem is essentially developing that new branch of mathematics that works for Quantum Theory. | 1 |
96ayxm | Biology | How do spiders know where to build their webs? Will they just build a web at the first location possible to build one or do they choose sites that are more likely to be on a flight path? If so, how do they ‘know’ this? | I've previously heard it explained this way: Spiders, like all insects are like very simple robots that obey very basic directives. Spiders are 'programmed' find a spot with good airflow, and build a web there. If they catch stuff, they survive. If not, they probably die. That's OK, because successful spiders have hundreds if not thousands of offspring. | 9 |
83zsac | Biology | Did survivors of the black death gain resistance or immunity to it? And if they did, did they pass any down to their children? | It depends on what disease it was. If it was Yersinia pestis, which is the dominant theory, the survivors did probably get at least some immunity to it. There is a vaccine against Yersinia pestis. I don't know how much data there is on how effective it is or how long it lasts. Plague isn't a very common disease anywhere other than the Third World, so it isn't regularly vaccinated against. There are other theories as to what the cause of the Black Death might have been. If it was a viral disease like smallpox or measles, then they would have been immune for life. Some viruses mutate over time, like the flu virus. If it was a virus like that, they would not have had immunity. There are some diseases where immunity wears off over time- pertussis and tetanus are examples. Children of plague survivors were more likely to be resistant to plague, because the people who were most vulnerable to plague were likely to die during the plague and not have children. | 7 |
lxegi6 | Other | What is the concept of months? Why Feb has only 28 while some have 31? When did the concept of 365 days' year come in people? | The short answer, Romans, the medium answer, Julius Caesar + the Egyptians. The more complete answer is that the Romans had the concept of months since their founding, following a lunar cycle with days added every time the year got too out of sync with the seasons. In the year 46 BCE, Julius Caesar decided that this system was dumb, and easy to manipulate (because he had been the one doing the manipulation for the last 20 years). So he recruited the help of some Egyptian astronomers to revamp the calendar. Egypt had a 365 day year, divided into 12, 30 day months, + 5 days at the end. (They actually had several different calendars, but this is complicated enough as it is) Julius coopted the Egyptian system, with a few modifications. First, he made February 28 days, and put those other days into 31 day months. This is because the Romans had a superstition that February was an unlucky month. Then, he took the +5 extra days, and also put them in as other 31 day months. Last change he made was to automatically add an extra day to February every 4 years to keep the alignment with the seasons. | 2 |
cwgoi0 | Culture | You see tons of British people playing American characters in popular American movies but the opposite isn’t so common, why? | I think there's also the fact that American actors find it more difficult to adopt British accents. Meanwhile, people in the UK have been exposed to American media more, so they are already quite familiar with the American accents and have an easier time mimicking them. | 2 |
k1k8bi | Other | What's the difference between identifying a stereotype and being racist? | A stereotype is an oversimplified image of a particular type of person. This could be old, young, girl, boy, Polish, Japanese, etc. Racism is prejudice, discrimination, or antagonism of a race. Usually based on the idea that one race is superior to another. So you can use stereotypes as a racist tool. But it can also be used not just against race. | 1 |
i0qafi | Biology | How does squinting helps us see better? Is it psychological? Does it ACTUALLY do something? | Squinting does work, for two reasons. First is when you squint, you block light coming in from the sides (your peripheral vision). By decreasing the amount of light coming into your eye, you're able to better process light coming from the object farther away. Second is when you squint, you slightly change the shape of your eye. By changing the shape of the lens in your eye, you can change the focal point of the eye to be closer to the object you're trying to view, just like a camera focuses. | 2 |
6eo275 | Economics | How do people spend large amounts of illicit money without getting caught? Let's say a drug dealer earns $1M a year. Obviously he can't put that money in the bank so he pays cash for everything. How does he buy a new car or house which have to be titled and registered without triggering IRS scrutiny about where his income is coming from? | Money laundering. He runs the money through a front. This can be as simple as having a friend that owns a bar, lists the drug dealer as an employee, rings in an extra $500 a night in sales and gives the drug dealer a paycheck. Or they get payouts as an investor in the front organization. Either way, in the eyes of the IRS, the drug dealer is legally making that money. | 3 |
5ymtek | Engineering | What are Tesla's "Battery Farms" and how do they work? | They are a bunch of batteries that store electricity. Usually electricity from things like solar or wind. Solar and wind energy isn't created on demand. Its created when its created. So you store it in a battery farm. The battery farm then provides energy on demand, like when you turn on your air conditioner or clothes washer. Works like a capacitor in electronics: smooths out the flow of electricity(voltage in the case of capacitors). | 13 |
amefvp | Biology | Why can we walk for hours without our legs hurting, but when we stand in place we get discomfort quickly? | What a lot of people don’t realize about standing or sitting is that you’re still using your muscles to maintain that particular posture. However, because there’s not much motion, you’re really using the same muscles for hours on end, which can create discomfort, soreness or fatigue. Comparatively, when you’re walking around, you’re alternating between multiple groups of muscles, leading each group to split the amount of time being active | 7 |
70x0rw | Biology | Apparently, the smell of freshly mowed grass is actually chemicals that grass releases to warn other grass of the oncoming danger. Why would this be a thing since there's literally nothing grass can do to avoid the oncoming danger? | I can't speak for grass, but tomatoes under attack by caterpillars can boost defensive chemicals that make their leaves taste horrible, causing caterpillars to [eat each other instead]( URL_0 ) and save the plant. Incredibly, [some plants]( URL_1 ) are capable of ramping up their defences simply by *hearing the sounds of caterpillars chewing*. | 33 |
92o5zu | Physics | Water is transparent but a stream of water has shadow. I was waiting for the bus and I realized that the fountain upwards stream had shadow, but since water is transparent how is this possible? | Light can go through water, but it comes out bent in a different direction. The places that light gets bent away from are in shadow. | 9 |
eza7rz | Physics | How does the end of a whip travel faster than sound when the person’s are doesn’t go anywhere near that fast? | So when you throw a ball, your hand goes faster than your elbow, and your elbow is going faster than your shoulder, right? So a whip is like a continuation of that, the tapered shape of the whip accelerates each progressive bit of the whip faster and faster as it gets smaller and more flexible as you move towards the end. Eventually, if you whip it good, a part of the whip exceeds the speed of sound and you hear a 'crack'. Doesn't necessarily have to be tip, though. | 3 |
7854id | Biology | how can the same DNA build three completely different forms of a butterfly (larva, pupa, adult)? they seem like completely different creatures -- different number of legs, wings, organs, diet etc. does their DNA have multiple time-activated blueprints or something? | Short answer: epigenetics Now with that said its basiclly because genes are switched on or off due to their purpose and the enviornment. Its the same reason why our ear has the same DNA as our leg although theyre pretty didferent. | 3 |
jo39bp | Physics | Why are X-ray and gamma-ray emissions considered radio bursts? As in FRB's (fast radio bursts). Radio = radioactive? | In astronomy, bursts are describing the pattern in which the light radiation is emitted, the gamma/X-ray refers to the wavelength of light that is emitted. So for a Fast Radio Burst, it’s a very short, non-repeating flash of light in the radio-spectrum. Like a flash bang except in radio-light instead of visible light. | 2 |
9m5bzx | Chemistry | How can aluminum foil, a metal, be in a 375 degree oven and not be hot to the touch? Making cinnamon rolls... | When you touch a hot object, heat is transferred to your skin - in the process cooling it down at its surface. So the better the material you touch can transmit and store heat, the hotter its surface will be when you touch it. So for example, you can stick your hand into the oven, as long as you don't touch anything - the air simply doesn't transfer enough heat quickly enough to give you burns. But a steel or aluminum tray will burn your skin within a fraction of a second, since those are quite good at storing and conducting heat. But you can touch hot aluminum foil inside the oven without issue, since it's so thin that it'll cool down almost instantly where you touch it. [Here]( URL_0 ) is a demonstration of thermal insulation tiles which are used for spacecraft. As you can see in the video, these tiles are safe to touch, even though they're glowing white hot. It's the same principle. | 5 |
76iqv8 | Biology | How come when you are hungry your stomach feels nauseous? It seems like a design flaw that when you're hungry, you don't feel like eating anything. | The nausea is being caused by low blood sugar. Apparently, when your sugar drops too low (or too high), your body alters your stomach contractions in order to change the rate that food moves through your system. Source: URL_0 | 11 |
5uv8wr | Biology | Why do people claim that Fluoride is harmful? | Essentially hogwash. It's one of those things people freak out - it sounds scary, flourine can be harmful in certain forms, and people don't trust the government to do anything. However, it can be harmful if you overdose (one of the reasons you're not supposed to swallow toothpaste), but it's nothing you need to go crazy worrying about. It's not going to happen in the levels found in community water supplies. via: URL_0 > Prolonged ingestion of fluoride through drinking water, in excess of the daily requirement of 1.5 mg/L as the upper limit (as set by the WHO) is associated with dental and skeletal fluorosis.[2] Signs of skeletal fluorosis become evident on consumption of 8–10 ppm of fluoride in drinking water for approximately 10 years or more.[9] Note 1.5mg/L is roughly ~~ppm and URL_1 > Starting in 2015, the recommended level is 0.7 milligrams of fluoride per liter of water > National survey data show that prevention of tooth decay can be maintained at the recommended level of 0.7 milligrams of fluoride per liter of drinking water. This recommended level updates and replaces the previously recommended range of 0.7 to 1.2 milligrams per liter. > *Experts have weighed the findings and quality of available evidence and concluded that there is no association between water fluoridation and any unwanted health effects other than dental fluorosis.* > The independent, non-governmental Community Preventive Services Task Force has noted that the research evidence does not demonstrate that community water fluoridation results in any unwanted health effects other than dental fluorosis, a condition that causes primarily cosmetic changes in the appearance of tooth enamel. | 9 |
l77sd9 | Chemistry | How do those silica gel packets “keep things fresh”? | They absorb moisture from the air around them. Thus they are used for things that should be kept dry as they'll mitigate the effects of humidity. They don't work indefinitely though, so you're still supposed to keep the product somewhere relatively dry. | 2 |
lxf33x | Biology | Why is it that the brain can generate music with extremely high clarity but not as much with smells and tastes? | Smells and tastes are simple *things*, but music is a set of complex patterns. Our brains are designed to learn and memorize patterns because that ability is useful to survival. I'm a fan of classical music, and I always marvel how so many high level conductors have committed to memory incredibly dense and complex pieces of music. Here is a performance of the well-known [Beethoven's 9th Symphony,]( URL_0 ) conducted entirely from memory by [Daniel Barenboim.]( URL_1 ) | 6 |
g6rkn2 | Biology | Does pregnancy delay menopause? If the number of eggs women have is finite, and you drop 1 egg per month during the standard cycle, do you delay menopause by 9 months every time you get pregnant (assuming full term pregnancies)? | No. One follicle is matured and released as an egg, but other follicles die in the thousands every month regardless of ovulation. Same idea works for using birth control - just because it prevents ovulation, it doesn't mean it will delay menopause/prolong fertility. | 1 |
bl8nri | Biology | - Why is a plant based diet ‘more sustainable’ than meat/seafood. Won’t we start over farming and ruining the land if everyone was vegan? | URL_0 Kurzgesagt - Why Meat Is The Best Worst Thing In The World I highly recommend you watch it if you have spare 9 minutes (please do, it's much better than many videos you'll see). The team used sources for making that video, so you can be safe that the numbers are based on articles, which are linked in the description btw. | 38 |
8pzjy5 | Other | How do cops prove you’ve been over the speed limit? Do they always need conclusive proof to write you a ticket? Sorry in advance for all the follow up questions, I’m just a curious 16 year old. | Generally, they hit you with a radar gun, and that logs your speed. If you get pulled over, ask to see the radar gun. If they can't/won't show you, you have something for when you go to court. If they are pacing you but don't hit you with the radar, you can claim their speedometer is off. Around here, that requires sending the cluster of the cruiser to the capital for calibration and verification, most of the time they'll let you off with a warning unless you were just going stupidly fast. I've used both when pulled over, but generally they've got you pegged before they ever kick on the lights. | 7 |
9ap8fn | Economics | The Efficient Market Hypothesis I don't get it! It's been annoying me for quite a while. Particularly the "strong" hypothesis. How are some investors so rich if the hypo holds true? | Well, lets start by assuming the market is not efficient. Every Friday, markets go up because people get excited for the weekend, and they drop on Monday because people are depressed on Monday. So you start buying stocks on Monday and selling on Friday. Soon you make a fortune. Now when you make your purchase on Monday, the amount of buying you do drives the price up since you're increasing demand. And when you sell on Friday, the amount of selling you do drops the price because you're increasing supply. Eventually, everybody else figures out what you're doing - and prices no longer go up on Friday and down on Monday. Your market inefficiency no longer works. Now, imagine millions of smart people (and computers) looking for these little market inefficiencies. Whenever one is found, it effectively gets removed from the market. Eventually, there are no more market inefficiencies. You can still make or lose money in the market, but it's more due to luck than some random of buying on Monday and selling on Friday. How can people get so rich if this is true? Perhaps it's just luck. Some people believe that Buffett got primarily by using other peoples' money to inflate his returns (his biggest investments in insurance allow him to invest something called the "float"). Some people just get lucky and make it look like they're good. Some people do illegal things (Jim Cramer has admitted to illegal market manipulation). If you really want to see the wild west, you could try to invest in ultra microcaps - $100 million market cap or less. These markets are much less efficient than what you see on CNBC but they're very risky. | 1 |
klcwpk | Other | How come they still discover new things in Pompeii? Hasn't it been searched out before? How humongous is Pompeii?! Edit: THANK YOU ALL FOR YOUR GREAT ANSWERS! :D | They knew that future archaeologists would have more advanced tools and techniques, so they deliberately left many areas unexcavated. URL_0 | 8 |
5yw7a4 | Economics | Will automation cause an inflation or deflation on the price of goods and services in the future? | Automation, ignoring other factors, by itself will lead to deflation. Technology and automation reduces the cost a firm must pay to produce something, and this cost reduction will be passed on to the consumer, lowering the price. If automation or technology hypothetically occurs across the whole economy prices everywhere will drop. However, the central bank will see prices dropping and increase the money supply, which increases the inflation rate. So in practice there will not be deflation because the central bank will adjust for it. There was a huge problem with deflation by exactly this mechanism I describe in the late 19th century in the United States. Because of the gold standard, the supply of money was fixed, so there was no monetary policy or central bank which could adjust in response to technology and automation. So just as I described, the overall price level in the economy dropped [causing serious problems.]( URL_0 ) | 1 |
5xuxeo | Economics | Why is it so frowned upon to be friendly with Russia? | [Nothing wrong at all so long a you're a democrat]( URL_0 ). Hillary Clinton wanted better relations with Russia so badly she used a corny joke to try to "[reset relations]( URL_1 )" with Russia. Obama mocked Repucblican warnings of a resurgent Russia with his "[the 80's want their foreign policy back]( URL_2 )" line Of course, Russia took advantage of weak policies and rhetorical red lines to embarrass the democrats to the point that they didn't want a reset anymore, they [preferred a war in Syria]( URL_3 ). | 30 |
fcw240 | Technology | If computers can process a billion tasks in a second, what actually happens when your computer gets really slow and takes 2 minutes to open the browser? | A "task," for the purposes of your sentence above, is simply adding two numbers together. There is a massive amount of "tasks" involved with even simply drawing a square on your screen. Opening a program involves loading it into memory, performing trillions of tasks to set it up, performing trillions more to start interpreting a web page, performing trillions more to display that page to your screen, etc etc... | 6 |
5sc7n0 | Other | is it logistically possible to choreograph sports games like football to make drama and determine the winner? | they do it in sports movies. I don't see why they couldn't do it in real life. everyone has a price. | 1 |
7fv07s | Repost | how does one alphabetize kanji? English for example has 26 letters in defined order and words or names can be sorted easily this way, for example, making directory for business employee or phone book, or dictionary for words. But in Asian countries like Japan, their name aren't spelled in letters but in kanji and there can be several thousand different symbols for words or names. How would a school sort student's name? Or how would a typical Japanese dictionary be sorted so they can quickly look up word? Not just Japan, but many Asian countries (China, Korea, etc) | Korean doesn't fall into this category: it actually uses a real alphabet. Those characters that look like complicated Chinese-style logograms are actually syllable blocks, made up of (usually) two or three letters that represent sounds, and these letters have a fixed order (however, North Korea and South Korea use different alphabetical orders). For example, the writing system is called "한글". It's two syllables, and each syllable is read from left to right and from top to bottom. The individual letters are: * ㅎ = h * ㅏ = a * ㄴ = n * ㄱ = g * ㅡ = eu (sometimes transliterated "ŭ") * ㄹ = l -- so: "hangeul". No problem at all: "ㅎ" is 19th in the South Korean alphabet. Chinese ideograms, or kanji in Japanese, are more complicated. They're sorted by radical and stroke count. The "radical" is the part of the character that gives you a clue about the meaning of a word. For example, the character "媽" means "mother": the radical is on the left, "女" and means "woman". The rest of the character, "馬", gives a clue about the pronunciation. Its actual meaning is "horse", but in Mandarin Chinese it's pronounced "mǎ". This is *almost* the same as "mā", the word for "mother", so the whole character means: "This is a word for a woman, and it sounds a bit like the word for a horse." There are a bit more than 200 radicals in Chinese, and they're sorted according to the number of strokes you need to write them. [Here's a list of the 214 radicals encoded in Unicode]( URL_0 ) -- notice how they get more complex the further down the list you go. So most dictionaries are arranged such that you first look up the radical, and then you look for the character you're searching for, again according to the number of strokes. If you want to look up "媽", for example, you need to first find "女", which is the 38th radical. You'll have a long list of characters that use that radical, again sorted from least strokes to most strokes -- you know that "媽", which needs 10 extra strokes, is going to be further down the list than "奴", which needs 2. [This is the list of characters that use the 38th radical]( URL_1 ) -- there are 681 in all. | 3 |
hqz2if | Biology | What is the biological mechanism behind post-nut clarity? | I'm not sure there is any; it could be that you have an anchoring effect; if your clarity of thought has been diminished while aroused, the removal of that will feel like an increase in clarity. On the other hand, it could also be that your brain has been overwhelmed by unnoticed background anxiety, and the oxytocin release associated with orgasm could be reducing anxiety and allowing you to think clearly. (If the latter is true, then it might be worth testing this by spending time hugging someone with whom you have a good relationship (yeah, corona, put a pin in this one). Get comfortable, hug, don't talk, and after about 15 minutes start also thinking about whatever you need clarity on. If it is the capacity of oxytocin to reduce stress that is allowing you to achieve clarity, then supportive touch could have a similar effect, if in a less focused burst.) | 3 |
jgmuzc | Other | What’s the point of third parties if they don’t debate or get taken as seriously as Dem or Rep? How likely is it for them to rise to that level in the future? | It is basically impossible for any third party to compete in a presidential election in the US due tot he way the US election system is designed. | 2 |
6cr4e7 | Repost | Why are flat head and Phillips head screws both so common? Why is there not one go-to standard? I understand the use of the other less common screws for various reasons - to avoid tampering or to avoid stripping, but why did no consensus ever form for the best "standard" screw to use. That way we'd need fewer screwdrivers! | Flat heads were the standard for many years. (They were easy to make) Phillips came out later and are better. But there are many more out now. Torx, allen, star, etc.... | 6 |
6686cq | Culture | How did baby boomers when they were young manage to pay for a house and raise a family while on single incomes (the dad working), yet today young couples can't even afford a small home and struggle to raise even one child while there's two incomes (mom and dad working)? What happened? | Due to demand for property prices of property increased faster then wages increased. This compounded for 15 years into the situation we have today. | 76 |
j2m9fp | Physics | Why do all of our planets orbit on the same plane, unlike electrons in an atom? | The planets started out as clumps of matter inside an accretion disk, which spun alongside the growing Sun. Like all spinning bodies, the weight of that disk tends to be pulled outward toward the middle, flattening it out substantially, like pizza dough when the chef throws it up. Because of this, the vast majority of the planetary bodies are going to fall within the same general plane of motion, with only some exceptions. | 4 |
iezp31 | Biology | If digestion is a long process, why can some foods cause a rush to the restroom minutes after ingestion? | I don't have a gallbladder so no large amount of bile to handle fats. A greasy meal can sometimes lead to a very pressing need to go. Takes 30 minutes to an hour after a meal. I've heard this called a dump. | 10 |
jt84u4 | Engineering | why is it that switching off an electronic device and switching it back on solves most of the problems we face with it? | You can think of any device as having a variety of 'states' - different configurations it can operate in. Some of those states in any complex device are going to be non-functional ones. Most of the time when you expire a cataclysmic error - one that stops your device from working - it's a consequence of being in one of those states. On electronic devices, power cycling resets the state to the initial state. That doesn't make it a universal panacea. There are ways to preserve state over a power cycle (fixed storage, for example). If you delete the O/S on your smartphone, power cycling isn't going to help you. | 2 |
hfm35u | Engineering | How do internet cables that go under the ocean simultaneously handle millions or even billions of data transfers? I understand the physics behind how the cables themselves work in transmitting light. What I don't quite understand is how it's possible to convert millions of messages, emails, etc every second and transmit them back and forth using only a few of those transoceanic cables. Basically, how do they funnel down all that data into several cables? | Hi! Here is a good link ( [ URL_0 ]( URL_0 ) ) on what the fiber looks like. It is super durable because, well, there is a lot of things that can go wrong at the bottom of the ocean. In essence, there are normally always one or two cable ships laying undersea cable at any given time, sometimes to fix lines that broke and sometimes to give more bandwidth. From what I have read before, to solve attenuation every 100KM or so there is a repeater device. There isn't only one or two wires in a cable bundle, there can be hundreds. The cable is huge, but the wires themselves are the width of a human hair. I can't find the exact number of wires in the undersea cable but from looking at the picture they must have at least 48 pair. So, quick explainer, on the internet you typically have one wire for send and one wire for receive. So if you want a 10Gb connection between two pieces of electronics, you would need two wires. So if you have a 48 wire cable, then you get 24 different send and receive pairs that can be put into electronics. Technology has come along and we know how prisms work. For example, I have residential F/O service in my house. They gave me 1 wire. So how do I send and receive? The technical answer is 'coarse and dense wave multiplexing' which is a complicated way of saying you can send a communication in one direction on one wavelength (or 'color' for short) and receive on a different wavelength. The colors are a handy way of talking about it, but these electronics can use the non-visible spectrum as well. I think, the last time I purchased multiplexing optics, I was able to get 10 10Gb pairs on one wire. So for that undersea cable, assuming it is 48 pin, it is 48 x 10 send/receive pairs. How the data actually flows? That is a topic called 'digital signal processing' (DSP) and you will need to ask another ELI5 for that. | 16 |
a0mof9 | Technology | How is water/waste recycle in a space station environment? | Urine can be filtered and purified to be drinkable again. Solid waste on the ISS at least is usually stored in waste tanks and later studied when it's returned to earth with the astronauts. | 1 |
gzipia | Other | Why is it considered disrespectful to do anything other than stand during the US anthem? Where did this belief originate? | It's not restricted to the US anthem - it's really for any national anthem (especially if it's your nation, but it's still a nice thing to do for other anthems). Because the anthem is a symbol of the nation as a whole. If you respect the anthem, you respect the nation. Historically it goes back to absolute monarchy, where the person of the King (Sultan, Tzar, Emperor, etc.) was equivalent to the nation as a whole. And since the King is the most important person in the room, everybody stands while the King sits. You can see the same ritual of respect in courtrooms today, where everyone stands up when the Judge comes in, and sits down only after the Judge sits. Fun fact: the name "Cathedral", meaning the most important church in a particular area, comes from a particular chair inside that church, where the bishop would sit during services - and everyone else had to stand. | 2 |
idb60q | Other | Why do your symptoms feel more severe when you think about them? | The same psychological loop is what causes panic attacks, for example. The brain is extremely powerful, and if it is convinced something is true, particularly something that elicits a strong parasympathetic (fight-or-flight) response, I.e. an unfamiliar or novel symptom, the negative feedback loop can often skew your perception of reality. | 7 |
70bicq | Biology | Sometimes when I close one eye at a time, I notice that each eye sees slightly different colors. Why does this happen and how does the brain resolve putting those two different images together? | I noticed this too. Mostly when I'm laying down on my side. My guess is that because of gravity the eyes have different pressure and amount of blood in them. Thinking of it now i don't see how it would have affect the perceived color saturation, but I was happy with this explanation until now. | 13 |
fwrl82 | Chemistry | When a pen quits half way through the word, why will it write on a fresh piece of paper but not over the words it failed to write in the first place? | Yes it's annoying that the ballpoint pen, first sold in 1938, still does not work very well and often skips or fails to write on thin hard surface paper such as restaurant receipts. Once an area of the paper becomes 'polished,' it is difficult to restart the ink because the ball slides instead of rolling. A new piece of paper is the solution. Very irritating! | 5 |
6lmx3w | Other | Why do "slips" happen, where you're sure you said one thing but actually said another? For example, I was having a conversation with a friend and said "Joe" instead of "Bob" even though I was *sure* I said Bob. Another time was when I ordered 6 piece chicken nuggets and I received 10 piece nuggets. I told my friend, hmm she messed up and gave me 10. He said "no you definitely said 10" but I was 100% positive I said 6. Why does this happen? | What's happening here with the memory is that you don't remember words per se. You translate words into concepts for memory, then back into words with recall. You remember what you intend to do, rather than what you did do. This is very common. Also, saying the wrong thing happens. Usually when you're not focusing on the task. Neither are uncommon. It just so happens both occurred together in this case. | 2 |
ktdopv | Technology | Why do people look ugly when they take pictures with their front cameras? | Usually bad lighting combined with wide angle lens being too close because you can't take a photo of yourself further than arm's length without some sort of holder. It fucks up facial proportions. Also if you mean your own photos, you are not used to seeing yourself the same way other people do because you can only ever see your face as a mirror image in real life and that's what you are used to. Set your phone on a timer, take enough distance to the camera, plan the lighting and flip the image horizontally afterwards and you will be happy with it. | 2 |
9r99to | Other | How does leasing a car work? I currently have a car and I still owe a couple of years on the loan. I would like to lease my next vehicle. How does leasing work and how does the loan effect it? | Leasing is basically just long term renting. You agree to pay a monthly fee/payment to use the car which is often restricted by how many miles per year you can put on the vehicle. However, they will often have warranties and/or allow you to trade in the car for a new/newer one at the end of the lease for relatively little new money. It's sort of like living in a hotel. You don't "own" the room, but you do get some of the benefits of using the hotel's staff and facilities. | 1 |
7kclvw | Biology | Why are pregnant women not supposed to lie on their backs? What will happen if they do it anyway? Will it harm the baby if the pregnant lady rests on her stomach? | The blood that goes to your lower body gets pumped back up to your heart through the inferior vena cava. The issue with being pregnant is that your uterus sits in front of it. Lying flat on your back late in pregnancy can cause compression and reduced blood flow to you and the baby. At 20 weeks, the baby is only ~1/10th of the weight it will be at birth so it probably isn't drastically uncomfortable yet. Later on, you may want to use (several) pillows to sleep angled to one side to take the pressure off. | 3 |
fuurx2 | Other | How come obesity isn't considered to be an eating disorder like anorexia? | Because they aren't the same. You can be obese without having a mental problem. You can also be underweight without being anorexic. Food addiction is an eating disorder iirc, and can lead to obesity. Anorexia is an eating disorder that can lead to being underweight. | 11 |
meazfx | Physics | How can nothing be faster than light when speed is only relative? You always hear this phrase if you watch something about astrophysics 'Nothing can move faster than light'. But speed is only relative. How can this be true if speed can only be experienced/measured relative to something else? | Here is the best explanation I've ever seen: URL_0 | 23 |
iiyofu | Other | Iambic pentameter Please for the love of god someone eli5, I understand RQM but can’t seem to make sense of this :( | A cadence, but a cadence, is what is To us iambic-structured prose must be. A lilt, a back and forth, as each new phrase - Syllabic wordplay coming off the tongue, Or off the page, just as the case may be. Great William Shakespeare's sonnets are indeed A great exemplar, with the adjutant Of regularity through rhyme and form. Some sloppy be with rhythm in this form, But if you keep it pure, I daresay yes, Few richer forms of prose can truly be. | 5 |
iwrb86 | Technology | why does resolution technology for small screens and larges screens advance at the same speed? shouldn't making a 4k phone screens be much harder than 4k tv's screen, since the pixels are way smaller? when a new resolution standard becomes popular, such as when "full-hd" and "4k" was new, they come to all devices at roughly the same time. this doesn't make any sense to me because a 4k phone has a MUCH higher pixel density then a 4k tv. example here: let's say aliens had the technology to make a "1 meter x 1 meter" screen with 4 pixels. logically they would also have the technology to make a "2 meter x 2 meter" screen with 16 pixel because they just need to use 4 copies of the 1x1 screen and put them together somehow. if they were to make a "0.5m x 0.5m" screen i would guess their limit would be only 1 pixel, that is they are even able to make a 0.5x0.5 screen with the 4 pixel 1x1 technology. but using our logic it wouldn't work like that, if we have the technology to make a 4 pixels 1x1 screens, we would also be able to make 4 pixel 0.5x0.5 screen, how come? | Your premise is wrong. The first 4k TV was released in 2012 -- > URL_0 The first 4k smartphone was released in 2017 -- > URL_1 That is a 5 years difference, enough time to minimize the tech. | 2 |
649xhh | Other | Why is it okay to eat/drink stuff in a US supermarket before paying for it? This doesn't really happen in my home country (Finland) | Generally customers will do this sort of thing because they're thinking like "But I'm going to buy it anyway so what's the problem" From the stores point of view though, a transaction hasn't occurred yet that transfers ownership from the store to the customer. They quite literally don't own the product they're eating (yet) Personally, I don't like it from the principal of "I don't own this item therefore I can't just eat it" but I get why people do it or think it's no big deal. | 20 |
nc7gv0 | Biology | what causes that cramp in your calf that wakes you up in the middle of the night? | This is called a charlie horse (not sure if that's colloquial or not, but it's what I've always heard it as). Your calf muscle tightens up and it can be very painful. The best way to stop it is to completely straighten out your leg and curl your foot/toes towards yourself. This will force your calf muscle to loosen. A charlie horse can happen because your calf has not been stretched enough after exercising it. It can also happen from sleeping with your calf muscle tightened, for example if you sleep with your legs bent very far so your heels are nearly touching your butt, or if you just go to sleep stressed out and don't realize your muscles are tight. To prevent it from happening, I recommend doing some light calf stretches before bed. While standing, out your left foot behind you and make sure your left foot's heel is on the ground. Straighten your left leg. Lean forward or move your left foot backward until you feel the calf stretch. Don't make it painful, as overstretching can be harmful. Hold the stretch for 10 seconds or so, then do the same to your right calf. Properly stretch calves are much less likely to experience charlie horses. | 2 |
5wd8f8 | Economics | why isn't it that people start their own one person insurance companies with their savings as payout money, and only insure themselves to avoid paying premiums? | If you have $3,000 in savings, it's not going to do much when you need life-saving heart surgery that costs $700,000, or when your toaster burns down an apartment building causing $350,000 in damages. "Paying yourself" the monthly premiums isn't going to do anything either. If you do have a lot of money on hand, you don't necessarily need insurance, but very few have that much liquid capital. | 3 |
iv2zvz | Biology | Why does salty food make us thirsty? | It's because your body doesn't like it when things are too salty in there, so it encourages you to drink some water to try to dilute the salt and bring things back to the saltiness it likes. | 2 |
7sbzp1 | Physics | Why are there no more big bangs happening? | The big bang refers to the point when the universe started to rapidly expand in all directions. We are currently inside this continuous expansion. If there was another big bang somewhere it would have to be outside of the universe. If there ever was another big bang we would never be able to see it. | 3 |
ifj76r | Engineering | When your car is in a tight spot (like exiting a parallel parking spot), you turn the wheel all the way to one side while stopped, you lurch forward slowly, after after a half tire rotation the car will suddenly turn a little more despite the steering wheel not moving. What's happening there? I hope I described this OK. I notice it every time I pull out of a parallel parking spot. It's like a little turbo-boost of turning radius. | Probably the power steering is unable to fully turn the tires while stationary, but rolling forward allows the tires to finish physically turning. If you're on a bicycle you can experience this easier, as turning the front tire while stationary will cause audible grinding between the rubber and the ground. | 1 |
d7lh4j | Technology | How does breaking one part of a screen mess up the picture of the whole thing? Screen being a tv, computer monitor, etc. | Each individual pixel in a screen needs to be controlled somehow. You can do this with a pair of wires to every single pixel, but that’s a lot of wires and very expensive with a high res screen. More usually it’s done by setting up a grid and scanning the screen with vertical and horizontal wires that “select” pixels as they go. But that also means a breakage in one of the wires can break a large section of the screen. | 1 |
9zo0ii | Engineering | why are there controlled engine braking zones? | In large commercial trucks and vehicles, engine braking preserves the life of the brakes but is also very noisy. Then they make it illegal to engine brake in residential neighborhoods/populated areas or between certain hours to cut down on noise pollution. | 2 |
iil49o | Engineering | Why do things turn red when heated? | Radiant heat is infrared which is a form of light that's lower energy than visible light. As something gets so hot and energetic that light moves up the spectrum and into visible light starting with red. If it gets hot enough it can even turn blue like the very base of a flame. | 1 |
5sfwru | Chemistry | Why cant we manufacture water by combining 2 parts H: 1 part O in gas form. Why doesn't it seem to be done? Why is water bottled more commonly?Isn't this a way to increse water? | The short answer is that liquid water is far more plentiful than gaseous hydrogen. Its just cheaper ti find it than make it. | 6 |
fdpoy6 | Technology | How is video footage shot in 30 frames per second much cleaner than computer recordings shot at 30 frames per second? | Simple: **motion blur**. Motion blur is "automatic" and "free" in analogic video footage, but costs a lot of computation to simulate in a computer animation, and is usually not done. This is why 24 FpS was perfectly good for decades and decades of movies, but 30 FpS was never quite enough for action games. | 2 |
8i7e6z | Engineering | Why do pen caps have a small hole? | I’ve heard that it prevents children from choking to death on it. If it gets lodged in their throat they’ll still be able to breathe through the hole. | 1 |
iibrcg | Technology | How do animators make cartoons that can go up to 30 frames per second in the limited time they are allowed? There must be some trick to it. I couldnt believe that animators actually slave there for days on end drawing each and every frame with body parts and mouths moved ever so slightly different. That they can do that thirty times for every second for a thirty minute to hours long video. It just seems impossible!! | Others have mentioned a number of tricks, but one thing that's often used (though not always) is that they don't often draw all 30 frames. When I was studying animation, one of the most common cheats was to animate on 'twos' - basically, showing a frame twice. Often, people can't really tell, and it looks better than just 15 FPS (for reasons I can't adequately explain, the science escapes me there). That having been said, as others have pointed out, you will try to save as much work as possible, by breaking bodies up into parts. If the mouth is moving but the body isn't? Just re-use the body, and only animate the head/mouth over top of it. It's absolutely crazy work, and you're not wrong to sit there in disbelief that people would actually do this. But they do. If you think traditional animation is crazy, stop motion is that to the nth-degree. | 4 |
7yfcvl | Culture | What is the history behind common calisthenic exercises such as push ups? | I'd try asking this question at r/AskHistorians. Very professional where I'm sure you'll find a credible answer. Edit - much has to do with the [physical culture]( URL_0 ) movement of the late 1800's. Long story short, large-scale industrialization took much of the workforce out of the labor intensive work of agriculture, into jobs where factory workers would continuously perform the same action over and over again. This led to a drop in overall fitness for the population, especially seen in the [Victorian Armies]( URL_2 ) of the time who noticed that many of their soldiers were ineffective due to poor fitness. Slowly, exercising and eating well were blasted into the minds of the public from media giants like [Bernarr McFadden]( URL_1 ) and gyms and exercise routines were built up around it. | 5 |
9d4yoq | Other | In animation, objects that are going to move in a scene (usually rocks) are a different color than anything around it. Why is this? | This only applies to traditional animation before everything started being done on computers. Each frame of an animation was a picture of a bunch of transparent sheets layered on top of a background. Each frame of an animated object was drawn on a transparent sheet, and then those would be layered, moved around, and swapped out to produce the final scene that was photographed, kind of like slides under a projector. It's basically just 2D stop-motion. So objects that will move look different from the background because they're a completely separate drawing. That static pile of rocks is part of the single, high-quality, painted background. That one rock that's going to move is drawn separately on a transparent sheet on top of it. Most likely more than one sheet since it will probably have multiple frames of animation instead of just a single image sliding across the scene. | 4 |
a29ddk | Technology | Why does the Google maps voice sometimes sound normal and then suddenly become robotic? | It depends on if it's streaming text to speech from Google servers vs if it's coming from your local phone. If you lose your connection or your connection isn't fast enough it'll default back to your phone's tts. Google's servers sounds natural, your phone's tts sounds kinda bad. | 2 |