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i7z7d0 | Physics | Does room temperature of 38+ celsius lower when you fill the room with people? | Assuming you're just starting with a well insulated box full of air at 38C and dump 20 50kg people in there that are all running at 37C you'll see a couple things happen. Initially the temperature of the room will drop a bit as the thermal mass of the 1000 kg of people absorbs heat from the surroundings and their sweat tries to keep them cool But people are basically 100W heaters and you just dropped 2000W in that box and this is where it gets tricky. The people in the box will be sweating, the evaporation of that sweat absorbs quite a lot of heat. While heating the 1000 kg of people (effectively water) up by 1C would only take ~4.2 MJ of energy, evaporating even 1 liter of sweat per person will absorb 45.2 MJ, that's 10x more. So what happens in this middle section is weird, how far the temperature drops depends on how much the people sweat and how fast they sweat along with how much air there is in the box to absorb that humidity But once the people have sweated all they can sweat you're back to a box with heat sources in it and the box temperature will continue to climb until all of the heaters have overheated and failed. | 2 |
aeiycu | Other | Why is it that a good bed is needed for preventative back issues? How did out early ancestors do so well sleeping on the ground and hay beds? | I’m sure weight plays a big factor. Most devolved countries have some pretty hefty people. Back then everyone was like 12% body fat | 5 |
hhjg6e | Technology | How can video game developers go into a specific player’s game, while that person is playing the game, and alter objects or the game itself? Example of what I mean in the desc. The developers of Cluster Truck went into this specific player’s game on livestream and began messing with his game, typing text on screen and changing the colors/speeds of all the trucks. [example]( URL_0 ) | As it says in the description of the video “Some people seem confused as to how the developers could've modified the game in the way they did, so I'll try to give a run down of how it worked. Clustertruck has Twitch integration, which is why that bar appears at the top of the stream. Each viewer can vote on one of three options, and one of those options gets picked randomly. Basically, all the game does is look at the Twitch chat, and knows to detect certain words or phrases, and that's why people are able to vote and their votes get detected. So when the developers joined the stream they began typing specific commands in the chat, like commands that turned the truck purple, or changed the gravity. These commands were only used by the developer, and I'd assume they did that by simply telling the code to only acknowledge those lines in Twitch chat if it came from that specific account. I hope that helps clear up some of the confusion.” | 1 |
igxg1r | Other | What is politics and what does mean to politicise something for example masks? | Society is made up of many, many people. Somehow we need to organize society in a way as to make it safe and helpful for the greatest number of people, so we create rules/laws we all agree to follow. These laws come into existence when our government passes policies. Policies are the end-goal of the process of politics. Politics is just people trying to convince other people that their opinions on various issues are correct. These opinions usually influence what types of policies these people want to pass. “Politicizing” something means that rather than letting a person/place/thing/event be as it is, it becomes analyzed and interpreted through political lenses. Suddenly something simple like wearing face masks in public, or what color cups Starbucks releases during holiday seasons becomes much more controversial, heated, and important to people. People are generally very defensive about their opinions on things; and as social creatures, we tend to seek out others who feel the same way about things as us. Thus we have political parties. Tribalism makes things even more heated and complicated. | 3 |
m1s1iz | Biology | How does the eye clean itself when lashes, tiny cotton strands, makeup, etc. go on the eye? One day a small eyelash was on my eye ball and I couldn’t get it out. I blinked and it rolled up inside and was gone. Where does it go? Does the eye do something to ensure it comes back out later through the front? I also wear eye makeup such as eyeliner, mascara, eyelash glue, eyeshadow, etc. and at the end of the day after removal I see black clumps in the inside corner of my eye. I’ll remove those, but I’m pretty sure I’m not getting all of it and a small amount goes into the eye. Where does all this small debris, loose lashes, makeup, go? Does it build up and get stuck in the back of the eye? (I saw some headlines where people have had tons of contact lenses getting removed but my question is focused on small debris like lashes and makeup). Or does something occur where it breaks down this debris? Or does it eventually come out through the front of your eye as eye crust? | It all gets washed out. If you pay attention when you feel you have something in your eye, you will notice that your eye tends to water a lot more - this is your body reacting to the debris and trying to help wash it away. Things like an eyelash stuck under your eyelid are a bit more awkward because of the larger shape, but the same still happens - as you blink it will be slowly moved down into the corner of your eye, and it will eventually work its way out of your eye and either fall away naturally, or be brushed away by you without realising. This is why you may also find a small clump of eye makeup appear in the corner of your eye, or the gunk left behind after sleeping - your eye has slowly been washing out any debris that has gotten into it over the day, which will collect at the corner of your eye. As the moisture dries out you are left with the makeup/gunk. | 3 |
8royru | Chemistry | Why does a frozen water bottle explode in the freezer when the water becomes ice if the particles are more densely packed and should thereby occupy less space when solidified? | Most liquids take up less space when they freeze into a solid. This is because, as you have pointed out, solids are typically denser than liquids. But water and ice are an exception - ice is *less* dense than liquid water. This is why it expands when freezing, and also why ice floats. The reason why is complicated, having to do with the crystal structure of ice and the hydrogen bonds the molecules form. Hopefully someone else can explain that part better than I did. | 2 |
h8y7el | Other | how a company can take minutes, hours, or maybe days to process your payment. How is it they can take sometimes months to process a refund? | The company has a lot more incentive to process your payment quickly than your refund. The first puts money into its bank account; the latter takes it out. Though taking multiple "months" after knowing they owe you money is pushing it. | 2 |
d7e9rl | Biology | why do babies cry right when they’re born? | It's cold, it's bright, it's scary, they suddenly are forced to breath air into their lungs, they've been smooshed through the birth canal (no simple thing to go through) or forcibly pulled out of the womb (via C-section). In other words they have to get the attention of their mother to save their life (warmth, food, security) from the elements. You see this in other species as well at birth. | 1 |
5qu3b5 | Biology | what is it about apples that makes us have so much variety compared to other fruits? For example, at any supermarket I go to, there's at least 6-8 kinds of apples. This is not the case with other fruits. | In many cases there are in fact many different kinds of a fruits or vegetable. We just either dont sell them or they got breeded out for what was considered better looking or tasting. For example there are multiple types of bananas, oranges, ( berries in general actually), etc. Theres also variety in vegetables with various kinds of greens, peas, corn, carrots, etc. Carrots are a prime example of breeding out different types. The orange one you see today was created mostly by cross breeding, not naturally As for fruits that only have one type thats mostly because they only grow in a very select few places under fairly strict weather requirements leaving little room for mutations. | 1 |
cxqhmz | Biology | Does a caterpillar feel pain during metamorphosis? So a caterpillar makes a chrysalis, dissolves into goop, then reforms itself into a butterfly. Does having it's body dissolve hurt? Does regrowing? Do we know? Do we have any idea what it perceives and for how long? | Some please answer this! I get asked this all the time by little kids at work and I have no idea. | 3 |
jk2v41 | Other | Why do we “gag” and want to throw up when we put fingers deep in our mouth? | gag reflex It’s for your survival, if you’re choking you gag and that tries to help push back out whatever is stuck. When you have a kid and they are just starting solids you’ll see this work a lot. | 1 |
6p5iag | Biology | How did early humans, or those part of small tribes and villages, survive genetic disorders of inbreeding and did not become extinct? During some preliminary research, it is shown that inbreeding has "increased levels of mortality and morbidity due to a variety of genetic defects". ^[1] Now, with that statement, how did early generations of humans when we weren't as diverse nor had big populations survive without the terrible genetics disorders inbreeding causes? This questions could also be valid for remote and small villages and tribes. Source: ^[1]: URL_0 | One method that dealt with this is familial locality based on sex. In a patrilocal society, the men of the tribe remain and marry women outside of their tribe who then live with the man's family, while the women are sent to neighboring tribes and stay those men's families. In a matrilocal society it's reversed. Women stay with their families and the men leave the tribe and live with the neighboring tribe's women | 7 |
j6q7xj | Technology | How come TV remotes are still so bad? | I have a harmony remote that uses my home wifi and it is much more responsive than the TV remote. Works by putting a base station or optional IR repeater somewhere in the room with direct line of site to the TV. The remote sends signal over wifi to the base station, the base station pumps out the required IR signals over a much wider area. Also lets you use your phone as a remote. Hopefully TV manufacturers catch on and start making wifi enabled remotes and we can get rid of the IR nonsense completely. | 15 |
6x70jl | Biology | How come if you stay up late because you don't feel tired you will still feel exhausted the next morning? | Are you asking why you are more tired in the morning when you get less sleep at night? | 3 |
jzm1w6 | Other | what do guilds actually do? In fantasy RPGs and such they're usually a bunch of guys who stand around giving out quests. But what did guilds actually do in real life? Like a Trade guild or something like that. | As u/rhomboidus mentions they were also a tightly integrated form of early regulatory agencies. For example, C.F. Martin (european guitar maker ca. 1840) was raised in the Cabinet Maker guild but wanted to make guitars, a newish instrument at the time. When he started producing them the violin-maker guild didn't want to be associated with him to so he did it as a member of the Cabinet maker's guild. Once he was successful, and the guitar as an instrument gained popularity, the violin maker's guide took him to court saying that they should control all string instruments, because cabinet makers didn't have the technical ability. Martin was ultimately successful by having his client's play the guitars to court, proving that cabinet makers had the proficiency to make fine instruments. He was still disgusted by the litigation though and emigrated to NY, reinvented the Western Guitar as we know it and founded the C.F. Martin guitar company in Bethlehem, PA. | 4 |
ej08zh | Technology | How do game developers build games around next gen consoles without knowing the software/hardware of the systems | Most games are developed so that the game doesn't care what console it's going to be played on. Then the studio will use a SDK, System Development Kits, for a console to make the game run on the console they want it to work on. For todays and future Xbox and Playstations they usually develop like they were making a game for PC, because the hardware is very similar, just that the consoles are very specific while PC is very undetermined. It is also very common to use a game engine, an already created framework to create a game on, like Unity, that in itself provides tools and assistance to make a game run on different consoles. Certain, specific studios also get information beforehand what the hardware, or at least performance, of the new consoles are going to be and can create a game accordingly. They have to sign a contract that says that if they tell anyone else this information they're going to be in big trouble. | 3 |
68k80o | Repost | How do music makers know if a melody has been taken or not? If say a song you thought up just happens to have the same melody as another song you've never heard of that's already been published and copyrighted how would you know before you make a mistake of using that song? | Would it be possible to play your melody into something like Shazam and see if there are any hits? | 48 |
a5cuf1 | Chemistry | When it's cold out, why does frost form on my car's windows, but rarely on my house's windows? | Your car sits out in the cold, turned off, and with no heat being generated to keep frost from forming. Your home is generally kept at a more comfortable 72°F, which keeps frost from forming on the windows as easily. If you were to keep your heater running in your car (you'd kill the battery), then the frost would be thwarted on the windshield, too. | 2 |
absk37 | Biology | transparent animals How are some animals "see thru"-clear-transparent? I just saw a video of an Anemone Shrimp, and I'm gobsmacked | There's a few main reasons why a part of an animal would be transparent. It could be a really thin clear membrane like the parts of a fly's wings that are between the structural supports, or or the creature is made up of some sort of transparent jelly (like most jellyfish). But a lot of the time, especially for small but complex creatures that are almost all transparent, it's for camouflage. Being transparent makes it harder to see them and they can use that ability to either avoid getting eaten, or helping them hunt undetected so they can more easily catch and eat other things. You see it a lot in very-deep-sea animals that can be given away by the least little bit of light, or in very young animals like eels that must do their best to hide from predators until they're older and larger. How they get there is their ancestors evolved to remove as much pigment and light-blocking chemicals as possible from the area as a survival strategy. Instead of making a "white" or "pink" shell, some shrimp changed to grow an outer shell that's perfectly clear like glass. "Glass fish" avoided growing scales with any color at all in them, and removed as much pigment as possible from their flesh so light could just pass straight through. You can see their organs, and eyes, and backbone, but the rest of them is amazingly clear. And it's not that hard to get there, particularly if you're tiny. Most animals, including humans, are fairly translucent already. You can see this by putting your finger on the end of a bright flashlight and noting that some of the light shines through. The thinner the skin you put in front of the flashlight, such as the webbing between your fingers, the more light passes through. . | 1 |
9mv442 | Biology | When people die from Overdose, would it be peacefull or painfull. | That depends entirely on the drug. There's no single answer. It also depends on how large the overdose is, I.e., if it's just enough to be fatal, or several times a fatal dose. | 3 |
e6ofpe | Biology | How do we know that a species has definitely gone extinct (as opposed to just being extremely rare/elusive)? | As everyone else has said, we don’t. One of the poster child cases for captive breeding programs is the [black footed ferret]( URL_1 ) which was thought to be extinct until a population of 18 was discovered. Now the population is over 1000 in multiple locations to help protect them from complete extinction. More recently, [the widely thought extinct Vietnamese mouse deer]( URL_0 ) was captured on game cameras by biologists after having not seen it for 30 years. | 6 |
fcaztw | Biology | To what extent can animals of the same species communicate with each other? | It really depends on the species in question. Some of the larger mammal species are reported to have fairly complex languages, this includes wolves, dolphins and (if I remember correctly) whales. | 2 |
993vew | Physics | Why can't we capture and store sound energy? | You can. Wouldn't really be that difficult. Essentially just wire a microphone up to a battery charger. Microphones work by the sound vibrating a magnet inside a coil so that its movement generates an electric current through the coil. So use that electricity to charge a battery and you've stored sound energy. The problem is the amount of energy you'd get from it would be negligible. It's just unlikely to be useful for anything. | 2 |
7d2uzz | Mathematics | Encryption and decryption with prime number factorisation I'm really good at math and I have a decent grasp of computer science. I understand that multiplying two prime numbers to get a huge number is easy, but checking out if a huge number has only two prime factors is a monumental task for a computer. What I don't get is how this is used for encryption and coding and decoding messages. I keep reading about this in books and they keep talking about how one side is the key or whatever but they never really explained how it all works. Every book seems to love explaining the whole large-numbers-take-a-lot-of-time-to-factorise concept but not how it actually works in encryption. I understand basic message coding--switch around the alphabet, add steps that changes a message into a mess of letters; then the recipient has to do all those steps backwards to change it back. How do prime numbers and huge numbers fit into this? How does knowing a pair of factors enable me to code a message and how does knowing the product enable my recipient to decode it? | Any chunk of data handled by a computer is technically just a number. This could be a file on a disk, or a string in a database, or a packet sent over a network, it's just a sequence of ones and zeros. Interpret that as binary, and you have a number. The simplest kind of encryption is that you have a secret large prime number. You multiply your data (which is a number) by that secret number, and you get a new "encrypted" number. Since, as you say, multiplying (and dividing) by large primes is easy but factorising is hard, anyone who gets hold of your encrypted number can't easily factorise it, i.e figure out what the two original numbers were (your secret and your data). But anyone with the secret prime can do a simple division and get the original data out. In reality, it's more complicated in ways that i don't even understand. The algorithms are much more complicated than just multiplying by the secret prime. There's one way hashes and assymetrical encryption with public and private keys. But to basic principle is that all of your data is a number, multiplying is easy and factorising is hard. | 8 |
6jiycy | Biology | How do ants and termites design such complex and sophisticated large-scale structures? | A current belief for how ants create such complex structures is called [Stigmergy]( URL_0 ). Essentially individual builder ants follow specific rules where if the environment meets certain conditions they will build in a specific way. So as a made up example, if a tunnel is x long then turns right an ant may use these conditions to build a separate branch to the left. Add in some pheromones for communication and ants will work together to achieve simple tasks that result in complex structures. [Pheromones]( URL_1 ) are basically specific chemicals that ants and other organisms can produce and react to. There can be different kinds of pheromones such as alarm signals, food trails, and mating signals. As another made up example if a lot of ants are squeezing through the same tunnel there may be a lot of pheromones lying around and builder ants could use those as a condition to make the tunnel wider. | 1 |
am28io | Biology | What does a cold virus actually ‘get’ from infecting us? | It "gets" the ability to reproduce. Viruses can't reproduce on their own. The only way for them to do it is to hijack the machinery in our cells that to turn them into little virus factories. | 9 |
5uyg99 | Culture | Why is there no security at train stations when there are so much security at airports? | It depends which train stations you're talking about. Here in France there are regular 4-man patrols of armed soldiers at every train station. | 38 |
ddgvp6 | Culture | Why is the term "coloured people" offensive, but "Person of colour" is considered politically correct? | Others are saying "history" but that's not really a complete answer. The term "colored" is racially charged because of instances like [colored water fountains]( URL_1 ), [colored bathrooms]( URL_0 ), [colored entrances]( URL_3 ), and more. In each instance, the one word *colored* is used to describe the people. That word specifically was used to isolate, demean, and otherize people. It wasn't "person of color" it was just "colored". That's the same reason why the "n-word" is so heinous. On its own, it's just a word, and at one time it was the "correct" word to use. But it wasn't just used to describe people, it was used to discriminate against those people. And centuries later, when the people who it was used against made it a point to say, "Please stop using that word because it was used to hurt us before," people *continued* (and continue) to use it *because* it is hurtful. It's hard to say the word is "just a word" when it's deliberately being used to hurt people, eh? And for the same reason, albeit with a lot less controversy, the word "colored" used in that way is hurtful because it's usually used to hurt. The other part of it, though, is "people-first language". When you say, "Person of color" the word *person* comes first, and that matters. When a sign says, "Coloreds only" it removes even the personhood of the people it's describing. They are not *people*, they are *colored*. It reduces them to a single defining attribute, which is the color of their skin. They are colored, and everything else about them comes second. On the other hand, "Person of color" emphasizes that they are, in fact, still a person and they presumably have many defining characteristics. Many people of color may have a lot of other things they personally choose to identify as before they identify as being of color. Think about it this way: consider a person who is biologically male, attracted to other men, flies planes commercially, loves cats, and has dark skin. Are they a gay black man pilot who loves cats? Or a pilot that loves cats, is male, is attracted to men, and has dark skin? Or a black cat lover male pilot who is gay? In other words, [what kind of guy are you?]( URL_2 ) The guy who started the fire? Or *fire guy*? Sure, it seems silly, but everyone has things they use to identify themselves with. And yes, as part of society we use a lot of short-cuts and it's usually easiest for someone who doesn't know that person to identify their race *first* because it's the most obviously visible part about them. There's nothing particularly wrong with that. However, again you have to keep in mind that they are still a person and regardless of how *you* first categorize them, *they* may not define themselves that way. People-first language is an attempt to keep that in mind by saying, sure, we're saying that your ethnicity is something other than white, but also that's not the only thing about you. You will see similar language used to talk about other marginalized groups. For example: person with a disability rather than a disabled person. The point is the same. They are not defined by their disability, they're a person who happens to have a disability. | 1 |
e7sqw2 | Technology | How those drink machines that can give you a large array of drinks at fast food restaurants work | They have cartridges of all the different concentrated flavour syrups, which are mixed in with the base drink based on the users choice. They also report back the most popular flavours - this is why you've probably seen things like Raspberry Coke in bottles/cans in stores. | 2 |
nddwfw | Biology | How does your brain 'realize' that you're home? Like after a road trip if you're asleep, on that final turn towards your house you'll wake up. How does your brain know that you're almost home? Edit: I'm 99% sure it's not a coincidence because even when I'm driving with other people who obviously wouldn't drive the same way as my parents, I still wake up at the same turn into my neighborhood every time. I could be dead asleep for the entire ride and I'll still wake up. Also doesn't matter which direction I'm turning from | Usually you travel on a highway for the most of the trip. You go faster, rarely stop, there are no intersections or hard turns. But this changes when you drive off the highway to get to your home which (presumably) is at some distance from the highway. There is a change in speed, stops and turns frequency. | 6 |
lgz7fw | Chemistry | Can I use shampoo in place of body wash? | I use shampoo as basically 'head wash' I have a big beard, so the only thing above my neck that isn't hair is my eyes, nose, and ears. I figure they get covered in shampoo anyways so why not give them a scrub | 8 |
9r9doi | Biology | Why do people jiggle their legs? | > Anxiety can translate very directly into an unconscious leg-shaking (or foot-tapping, which I’ll get to shortly). People with jittery legs apparently burn off more calories, but there are definitely better ways to work off those extra pounds, at least when you're in public situations. Shaking your legs while sitting sends a giant message to everyone around you about your inner feelings of anxiety or irritation or both. * URL_0 | 2 |
7ail2e | Economics | why would a company ever go public and accept investor money, which they have to pay back indefinitely, over loaning money, which only has to be paid off with interest? | Risk management. When a company decides to expand or enter rapid growth phase it needs a large sum of capital. Banks will be unwilling to loan that kind of money at that level of risk. What will they take as collateral? Next best option is to raise little bit of money from many individuals who believe/bet in company’s success. | 4 |
7auhtv | Other | the difference between murder and manslaughter | Almost all degrees of homicide are distinguished by intent. (These vary by jurisdiction) **First degree murder**-premeditation and intent to kill **2nd degree murder**-heat of the moment and intent to kill **Voluntary Manslaughter**- willfull action that could likely cause death but no intent kill. **Involuntary manslaughter**- negligent action that causes another’s death. | 2 |
ctpai2 | Other | is there a legal reason why people don't just make their own local insulin in America? | It’s not easy or cheap to make or to make in a quality that will (almost) guarantee no injury with use. Also, manufacturing drugs and distributing them without license and approval by the FDA is super-duper illegal. | 1 |
66yghx | Other | Why did the Soviet Union have such a hard time feeding its population. Russia, especially, seemed to have a lot of money, plenty of farmland, and a decent infrastructure. So, why did it have trouble filling its grocery stores with food? | Because at every level, the incentives were all in favor of people making decisions contrary to the public good. It was a logistical structure built around the premise that people would simply obey their masters because their masters worked for the 'public good'. On the one hand, working harder and innovating didn't yield any rewards. On the other hand, cheating the system *did*. So all up and down the system, you had people who were either withholding the full measure of their capabilities or turning those capabilities to graft. In contrast, an American farmer works harder because he makes more money. He doesn't under-report his production because it wouldn't make any sense to do so - he won't get paid for anything he doesn't report. Similarly, the people transporting, distributing and retailing the food are all primarily interested in getting the most they can to the customer so they can get paid. | 7 |
6wmpbl | Chemistry | why does plastic degradation take so long? As far as I know, plastic consists of hydrogen and carbon elements, which are very common in organic chemistry and living things in general. So how come it is so bad for the environment? Thanks. | Plastic is made from petroleum. The most common petroleum component found in most plastics is propylene (or propene). It's a molecule made of 3 carbon atoms and 6 hydrogen atoms. When heated up, propylene forms bonds with other propylene and turns into long chains called polypropylene. The reason things decompose is that micro-organisms like bacteria have evolved naturally to eat certain things. Food, clothing, stuff like that. Simple stuff made of easy to break down molecular chains. Polymer chains? Not so much. Bacteria have no idea what to do with it. They didn't evolve to eat it because it takes more energy to do so than it does "natural" organic compounds and there are plenty of other, easier things to eat and thrive on. In recent times, bacteria have been discovered that eat some petroleum products and plastics. | 3 |
ieim94 | Biology | Why are wasps so aggressive? | If you frighten one they can mark you with a alarm pheromone which will make others attack as well. Is it defense mechanism because wasps are both predator and prey. | 3 |
6iqlen | Biology | Why sometimes we can spontaneously wake up just before we needed to even tho we forgot to set up the alarm? | I read somewhere that a if your last thoughts right before you fall asleep is about what time you want to wake up, you will wake up at that exact time the next day. So far, it seems to have held true in my experience. Easier said than done, because making sure those are your last thoughts before you fall asleep means you are watching for the exact moment you drift off. Which ironically keeps you up. Something about how your mind unconsciously keeps track of time without your conscious effort. If your unconcious gets the message that you want to wake up at a particular time, it will do so almost down to the minute. | 3 |
6ld408 | Physics | Why does putting your car remote against your head increase the range in which you can unlock a car? | I recently took a course on wireless networking, and we discussed the physics of radio frequencies to understand the way radio waves propagate. My professor gave this same demonstration of how placing the key fob under your chin increased the distance it could reach your vehicle. His explanation was that the signal the key, or antenna, generates radiates omnidirectionally, or in a sphere centered around the key. By placing it under your chin, you alter the way the radio antenna behaves, changing it from omnidirectional to a directional antenna, so that the waves bounce off our body and merge with the waves going away from our body in one direction, effectively funneling them further away than they could reach just going out in all directions. The shape of the waves goes from a sphere to more of an oblong shape facing one way. We aren't adding any power to the strength of the signal, just altering the direction the signal travels in. He had some neat diagrams to aid in the explanation that I wish I had saved, but that is how I understand it to work. | 5 |
kwsqlt | Physics | Why are wet clothes harder to put on? | Unlike dry clothes, wet clothes tend to stick to your skin, as such the movement of your arms and legs into the wet sleeves and pipes of the pants is obstructed. | 1 |
mn6yd4 | Physics | Why are Newton's Laws of Physics called laws and not theories? | Laws are observational constants. When you drop something it falls down. When you push on something an equal force is applied in the opposite direction. There is no conclusion or idea of why this happens. Its just an observable thing that happens. This is what scientific laws are. Theories on the other hand answer the far more interesting why question. Why do things fall down when i let them go. To answer this you need a theory. | 3 |
k2omjo | Engineering | In regions that are "100% powered by renewable energy", what happens to the traditional power plants? | Almost always, fossil fuel plants stay online to support renewables. Nuclear has the least fuel support, then hydro, but their mix hasn’t really changed over time. There are small, rare, rural examples of almost completely renewable. | 15 |
63kyq9 | Biology | What happens on the nights where I feel like I didn't sleep at all? I just spent the night tossing and turning, constantly feeling like I was not-quite-asleep and pretty-close-to-awake. I am very tired right now. | Sleep occurs in cycles involving 5 stages. The fifth and final stage of each cycle is REM sleep, deep sleep, dead sleep. This the the sleep where kids fall off beds without waking up. This is where your brain gets the most rest. If a cycle is interrupted part way through, it can't just resume where it left off just it has to start from Stage 1. If you are continually interrupted and never enter REM sleep, your brain is never quite resting and therefore you will continue to feel tired. | 1 |
8nz61c | Technology | Can someone explain what the basic concept is behind multiplexing? With relation to networks would be preferable. | Me (Aaron) and my brother Bob are dating two sisters, Alice and Betty. We are all strange people, so me and Bob are each writing 100-page novels for our girlfriends. Each page that we write takes 2 days, and each page takes 2 days for Alice and Betty to read. We want to send the novels to them in the most efficient way possible, but because this is all fictional the post office can only mail a single one-page letter per day from our house to the girls' home. What options do we have? I could wait 200 days for Bob to write and send his whole novel, then I can send mine. But that makes Alice have to wait a really long time to receive her novel, and during the time that she's reading it Betty will just be sitting around idle, having finished her novel already. The whole thing takes 400 days. A better system might be for me and Bob to alternate mailing pages. As long as Alice and Betty are aware of the system, or we mark our pages with which one of us wrote them, this method still gets all the information where it needs to go but nobody is idling for nearly as long. It takes me 200 days to write my novel, and also 200 days to send it, and it takes Alice 200 days to read it. Bob and Betty also just need 200 days to write, send and read their novel. Instead of 400 total days, we just need (about) 200 total days. & nbsp; Often when sending data over a network, there are multiple senders and multiple receivers. The network can only transfer a limited amount of data per second. Since it takes time for the senders to generate messages and time for the receivers to process them, it's often most efficient to *multiplex* the messages by interleaving them into a single continuous stream, then *demultiplex* them at the receiving end. | 3 |
9w3dl9 | Physics | When dry clothes are hanging on the radiator, what happens to all that heat energy? I just feel that the room doesn’t heat up when I forget to remove the dry clothes from the radiator. In fairness, I don’t even know the process of drying clothes on a radiator, either. (My school didn’t teach physics at all but I’m trying to learn) | This isn’t as precise as some other answers but more of an ELI5 answer. The heat is trapped inside the radiator, in the same way that your heat is trapped inside when you wrap up warm on a cold day. | 4 |
c5mkfe | Economics | How is insider trading not realistically going on all the time? | Outsider here. I did a simple internet search for insider trading. Then looked in the News tab. It’s happening all the time. | 6 |
j4uikk | Physics | Why does electricity “arc”? To my knowledge electricity follows the path of least resistance. Therefore in my mind that should be a straight line, not an arc shape. Right? | Here you can see lightning looking for the path of least resistance URL_0 | 4 |
nuwsw4 | Biology | why is cancer increasing in young people? Is it just because we dont die of other things first? | There’s some evidence that prolonged/constant exposure to specific chemicals in plastics (BPA, phthalates, dioxins) might be contributing to increased cancer risks. Mostly through ingesting the chemicals after the plastic has been heated up and transferred into food/drink. The science is still out and studies are still ongoing and currently inconclusive... but I’m inclined to believe that has something to do with increased cancer diagnoses. It should be noted, however, that less people (relative to population) are actually dying from cancer these days. In terms of young people- I haven’t heard about a specific increase there. But yes, mostly the cancer rates are increasing because people are living longer and not dying of other things first. Majority of cancer cases are in people over the age of 60. | 3 |
5zknif | Culture | What is a Pop Up Bar? What are these types of bars and how to they make money if they only are supposed to exist for short periods? | There is no real definition of a pop up bar/restaurant, other than that they typically exist for a very short period of time and often occupy a space that is not meant to be a restaurant or bar. The ideas is that since they are limited duration, they are very trendy and people flock to go while they have the opportunity to do so. The owners can charge higher prices and have full bookings because there are so many people that want to experience it while they can. | 2 |
fa3y1m | Physics | What do the current SI definitions of kilogram and Kelvin actually mean? As per [Wikipedia]( URL_2 ), the new definition of kilogram is, "The kilogram is defined by setting the [Planck constant]( URL_1 ) *h* exactly to 6.62607015×10−34 J⋅s (J = kg⋅m2⋅s−2), given the definitions of the metre and the second.", while that for Kelvin is, "The kelvin is defined by setting the fixed numerical value of the [Boltzmann constant]( URL_0 ) *k* to 1.380649×10−23 J⋅K−1, (J = kg⋅m2⋅s−2), given the definition of the kilogram, the metre, and the second." These are the only two, in the list of 7 which don't help form an idea of what that quantity actually is. | The Planck constant is energy times time, which is momentum times distance, and momentum is force times velocity, and force is how you accelerate mass. So, with energy, distance, and time, you know mass. | 2 |
i6i71l | Engineering | waterjet cutters, how the hell do they work and keep such a high pressure and have such a straight cut | According to Pascal's law, pressure exerted on a liquid is distributed evenly throughout the liquid. So when liquid is exerted with high pressure through a small hole, the pressure remains the same but the area is extremely small. The makes the force exerted by that small jet extremely high. This makes cutting objects extremely easy. | 2 |
5pket0 | Biology | If scratching our skin is generally bad for us, why does it feel sooooo good? Dry skin, mosquito bites, rashes, etc. We know we shouldn't scratch, but when we do it feels amazing. How come? | Scratching in daily life isn't bad. It let's us monitor the health of our skin, alerts us to possible irritants. BUT when there is something for extreme going on like a mosquito bite or chicken pox, scratching the area doesn't protect us or remove irritants, bc they're already in us. Instead, we just scratch until a sore opens, which can lead to the irritant spreading to more areas, or can allow another infection to take hold | 1 |
a0w684 | Biology | why does hitting your fingertip on a hard surface hurt more when you’re hands are cold vs. when they’re warm? | Top comment from the google searched first response previous ELI5 on this subject: Credit /u/[blinkenpilz]( URL_1 ) "[blinkenpilz]( URL_1 )432 points·[2 years ago]( URL_0 )·*edited 2 years ago* Different sensations are carried by different types of nerve fibres in the body. Basically it's like this: there are sensory fibres that tell the brain what your muscles and tendons are up to (called 'Aα' fibres), whether there's vibration ('Aβ'), or pressure / touching and cold ('Aδ'). So-called 'C fibres' mostly carry pain signals and warmth. Now, Aδ fibres ('delta fibres') also carry pain signals, mostly of the fast stinging type. So when a limb is exposed to cold, these fibres are excited, so you get the sensations 'cold' and 'pain' at the same time (that is why cold is often painful). Pain on top of cold therefore makes the pain that much more severe. Source: doctor. EDIT: added last sentence for clarity" & #x200B; | 1 |
la5wmf | Biology | How do we think about moving our body without actually moving it? What's the difference between thinking about, say, moving your arm and actually doing it? What makes the first one just a thought, and the second one a decision + movement? Thanks in advance, sorry if it's a stupid question. EDIT: Wow, thanks for all the awards and great answers :) | Correct me if I'm wrong, because I absolutely have no idea what I'm talking about. But isn't it similar to the ideomotor effect when people play the Ouija board and they think that they're not moving the planchette when in fact they are? | 17 |
6173sn | Culture | Why do certain European customs switch the comma and decimal in numbers, but not in the written language? | The decimal point doesn't really have any connection to the period or full-stop that comes at the end of a sentence. There's no real reason why the two should or should not be switched. Both the comma and the full-stop are just indicators of pauses in speech, the comma shorter than the full-stop. But in numbers its just a visual indicator not really a reflection of pause. | 3 |
digwsp | Biology | why do doctors perform bypass surgeries instead of removing plaque from the patient’s arteries? Seems to me like it would be simpler to restore blood flow by removing the blockage instead of just putting a path around it? Or am I misunderstanding how bypass surgery works? | Sometimes that's what they do. In the UK, for example, they prefer to do the less invasive (and less expensive for NHS) balloon angioplasty with stent, where they put a balloon catheter into the artery, which crushes the plaque to make the artery wider. Then they put a stent in (rigid tube) to keep the artery clear. This is instead of the more dangerous and invasive bypass. My information is old at this point so this data has probably changed but they found that balloon angioplasty had approximately the same success rate as the bypass, but with fewer complications. So then they started to do the angioplasty with stent more. They can't just remove plaque but otherwise leave everything the same because the plaque could become loose and cause a blockage and/or stroke. My understanding is that these are two options that they may use and whether they use it or not depends on the patient, the doctor, and the hospital. Presidential candidate Bernie Sanders famously had a balloon angioplasty and stents placed after he had a heart attack a few weeks ago. A bypass would require long-term hospitalization and a lot of rehab, whereas Bernie was able to leave the hospital within a few days. | 3 |
alrxnd | Culture | What qualifies something as a language? Some languages sound very similar to each other, and can allegedly even be mutually understood when two native speakers of different languages speak to each other (like Afrikaans and Dutch). So, what key factors make a language its own instead of making them something like a dialect difference? Edit: Made the question a bit clearer. | There is no clear distinction. Mutual intelligibility is a useful guideline, but even that isn't an easy yes/no thing to evaluate: what percentage of the language do you have to understand to be mutually intelligible? What if the languages are mutually intelligible primarily when written, and not so much when spoken? On top of that there are phenomena like dialect continua, where you can draw a line on a map so that people everywhere along the line can understand the people near them on the line just fine, but so that the people at each end of the line can't understand people at the other end at all. Often cultural or political ideas are also involved: some people will talk about "Chinese" as though it were a single language despite the presence of many mutually unintelligible varieties, and some will split Serbo-Croatian into four different languages (Bosnian, Croatian, Montenegrin, and Serbian, i.e. one per country where Serbo-Croatian is primarily spoken) despite all four having a high degree of mutual intelligibility. This has led to the semi-serious saying that [a language is a dialect with an army and navy]( URL_0 ). | 2 |
izeq2k | Economics | What happens when you declare bankruptcy | You basically say "sorry guys, I can't pay my debt". So someone will check all your finances and decide what you need for survival. Everything else will be given to your debtors. After that for a few years you're responsible for giving everything you earn above a survival treshold to your debtors and you can't take new loans. After that period you're declared free of debt. This differs from country to country though, so depending where you are the details can be different. The idea for this is to prevent people from ending in eternal debt slavery, and also to protect investors or loan givers from giving their money to someone who will never be able to repay it (without taking more loans somewhere else) | 2 |
o9tdt0 | Other | How did coffee come to become so popular in Scandinavian countries? | The Dutch East India Trading Company mainly. They established strong colonies in areas that could grow coffee in the 1600s and became the primary supplier to the region. | 1 |
9pswpm | Physics | Why does the greenhouse effect doesn't work both ways? So, i had a discussion with a friend who denies that climate change is man-made. I refered to the greenhouse effect, and he asked why it wouldnt work both ways. I was a litle bit baffled, because i couldnt awnser that question, and noticed that i dont actually know in detail how the greenhouse effect works. So, if the gasses in the atmosphere stops the light to leave the atmosphere, shouldnt it also stop the light to get inside the atmosphere, and cancel itself out on the topic of global warmth? | It’s different wavelengths of light. The sun sends us a broad spectrum of light which warms the earth. The earth radiates back to space light primarily at longer wavelength infrared spectrum. Greenhouse gasses only block infrared light. It’s similar in concept to blue blockers sunglasses which also only filter out a narrow range of light | 2 |
eeo0sv | Other | How do this gold and silver rescue blankets keep people warm although they are so thin? | There was another post explains that heat is infrared light. The blankets reflect that light back into the user. This happens over and over all while losing very little heat through the blanket. It’s thin unlike a traditional blanket. Traditional blankets trap your heat in air pockets. You lose more heat this way as the heat escapes. Space blankets reflect your body heat back to you. It’s like recycling your heat to keep you warm. It’s pretty cool. | 4 |
dlgir9 | Biology | how do anesthetics knock you out within 10 seconds of being injected? | I guess I’m pretty qualified to answer this as an anesthesiologist. The length of time it takes for a drug to take action on the body depends on a few things. Since this is ELI 5 I’ll do my best to keep it simple. The two most common ways to receive a drug are by mouth (swallowing a pill or a liquid), or by having them injected into your vein (IV medications). If you take a drug by mouth, it will take longer to get into your blood stream than if you have a drug given through an IV. Giving medications through an IV will skip the stomach absorption, and will go directly through your veins, go to your heart, and then be pumped to your brain. If you have a very strong medication, like propofol, which is used to put patients to sleep, it will take 1 arm-brain circulation time to take effect, which is generally 10-15 seconds. | 6 |
5ydlip | Biology | Why cant we remember being born but we can remember other events fron childhood? | The part of the brain that handles memory, the hippocampus, only develops physically when humans are about 3, which is why, for most people, memories start at 3 or 4 years old. | 2 |
fdes93 | Biology | Why can't an eye transplant cure blindness? | These people are very right about the optic nerve being a big roadblock in the idea. But blindness can be caused by factors other than anatomical features of the eye. For example, the eye and nerve might be totally fine and working but there is an issue with signal transmission in the occipital lobe and the sensory information never gets processed. Even if you could attach the optic nerve perfectly | 3 |
5qvzf5 | Other | Do American citizens have a right to freedom of information? | There is an overriding concept in the American view of government: All government information is public unless there is a really good reason for it not to be. The law in most jurisdictions reflects this: citizens have a right to government information unless that information has been, by law, specifically excluded from disclosure. | 2 |
k8kjk1 | Biology | Why do fingers run cold even if they're involved in much movement, such as typing on a keyboard? One would for example work on the PC, typing a lot of text, and after a while one would end up with cold and clammy fingers. Or when playing an instrument (with keys). I've always wondered about how this can happen, because usually I'd assume something like "much movement" = "generating warmth". | Cold fingers can be a sign of bad blood circulation. Typically smokers who have smoked for many years can have this issue due to blood struggling to get to all the areas. Another reason is that your hands only have smaller veins reducing the surface area of the blood vessels which in turn transfers less heat through to joint/tendon and skin. Also another thing to remember is your hands usually have little to no fat insulating them. | 3 |
8mc29m | Other | Why is the ocean water so clear in places like the Caribbean but not at US beaches? I think the question speaks for itself. | More complicated than just contaminants. Taking the Pacific into account, for example, it's often a cold water/warm water difference. Santa Cruz has pretty murky water partially because cold water carries a bigger bioload, where most water in Hawaii is pretty damn clear | 3 |
9ov1x2 | Other | What is the difference between sink water in the kitchen and sink water from the bathroom? | There is no difference between the water that comes out of any faucets or spigots in your house or yard. It’s all coming from the same place. | 1 |
68872x | Culture | How come a majority of humans suffer from not having 20/20 vision? And how did we adjust to those people back in the day? I won't lie I'm watching game of thrones right now during battle of the basterds and somehow Jon snow and others can easily see across the battlefield. And I'm wondering 1. Why on earth are some peoples eye sight just naturally shitty and 2. Before the times of contacts and glasses, I feel like all the people with shitty eye sight were just cast aside. How did those individuals adjust to society? I can relate because if I take my contacts out I'm absolutely useless to anything outside of a three foot distance. | Back in the day people did not read. So having good eyesight was really only needed for ranged hunting, and detail crafting work. Your average person did not need to see good detail, they just needed to see good enough to get by. | 3 |
5qhjgy | Engineering | How do missiles like iron dome chase their target? | Missiles have four common methods of tracking Active: Missile has an onboard radar and uses it to track the target after launch (more advanced aircraft missiles and surface to air missiles have these) Semi active: Missile has an onboard radar and is receiving information from the ground radar as it's signal is bouncing off the target Semi active ground guidance: missile and radar both track the target, ground station makes final decision on what and where the target it Passive: IR and TV missiles track heat and changes/differences therein to find the target However, that was all extra stuff lol. I think the Iron Dome uses proportional navigation. Like the previous comment, it triangulates where the ground is, where it is, and were the the target is going to be and makes adjustments every few seconds. Since missiles don't react to threats (how would it see them) this is an effective counter missile guidance method. | 2 |
m4u4ew | Mathematics | what do we use linear algebra for? | Linear algebra is usefull for many many many things. Data analysis, physics, engineering, ... The limit is linear here, but linear algebra is so powerful that we actually linearize nonlinear equations (assume they are linear as long we don't move too far from the point we linearized at) because nonlinear algebra has no general solutions for many problems | 5 |
h0vo5v | Other | Christopher Columbus | He was the first imperial European to discover America. Once there, he proceded to colonise. His methods included enslaving the locals, kidnapping the locals and shipping them back to Europe for the slave trade there, dismembering them as punishment for failing to mine enough gold, and one or two casual genocides. All of this he proudly documented in his own journals. He is celebrated because he is considered the founder of modern America and that must be a great thing. However, since growing as a culture and coming to globally accept that slavery, dismembering, and murder are wrong, he's been seen more and more as the monster he was. The trouble is that his monstrous deeds cast America's origins in a bad light, so they don't appear too often in 4th grade texbooks. People are becoming more aware of their history and less accepting of the "America is the beacon of freedom and goodness" narrative so they're taking action against the celebration of monsters. | 2 |
dmeg1r | Physics | - is the solar system actually horizontal? | The solar system is a flat plain (more or less). This is caused by the accretion of material during the formation of the system. The sum total of the inertia averaged out to cancel most motion out of that flat area As for horizontal- there is no reference point for that. A straight up and down depiction would be just as accurate, as would any other vantage point. There’s simply nothing within lightyears to give any reference to | 3 |
g36ycv | Technology | How are successive generations of data standards (USB, HDMI etc.) able to pack more features (data speed, quality etc.) into the same form factor ? For example, HDMI generations appear to have the same connector, yet the new generation has more features than the older one. | Lots of complicated reasons. For one, as technology improves, we can send the zeros and ones across the wire faster and faster. Since our processors have gotten so fast, they're able to read signals off the wire faster than previous generations. To put this into perspective, one of the most widely used serial protocols is RS232. The fastest official transfer rate is 19,200bit/s. The ethernet hardware in your PC is most likely capable of 1,000,000,000bit/s, and even then that's an old standard that's pretty slow. New standards are ten times faster. Raw processing speed isn't enough though. As signals on the wire get faster, weird things happen. The signal is strongly affected by outside interference, and sometimes it even interferes *with itself*. To combat this, we develop new cable technologies, either shielded copper, or fiber optics. But that's still not enough, we sometimes need special hardware to clean up the signal and extract the data from the noise. These are very specialized computer chips designed specifically to deal with noisy signals. This technology is still relatively new, and improving rapidly. On top of all that, we keep just simply adding more wires. For instance, USB1 and 2 use a single twisted pair for data. Basically, one data connection shared between upload and download (that's why it's called universal *serial* bus). USB3, on the other hand, adds two *more* data lines, tripling the total amount of data one cable can carry. To even further increase data transfer rates, some systems use compression. Since processors are so fast now, it actually makes a lot of sense to compress data before it goes on the wire, and decompress it on the other side. Generally speaking, the slowest part of your system is going to be data transfer. If you can reduce the total amount of data you put on the wire, you reduce time spent waiting for the transfer to finish. These data transfer technologies have a lot of components, but each one is improving independently! With each generation, most or all of the components involved has improved, which tends to result in massive gains when it's all put together! | 4 |
9rd3yg | Biology | How does PrEP work? ELI5: How does PrEP work ? How are they able to prevent the spread of HIV but not cure it?? | HIV is a single strand RNA virus. When a single stranded virus copies itself, it uncoils the RNA and creates a matching strand, turning the RNA into double stranded viral DNA. If you can imagine a zipper with only one side, but as you zip it up the other side magically appears, that's kind of how reverse transcriptase works. After HIV creates the viral DNA strand, it moves into the nucleus of the host cell. PrEP works by blocking the reverse transcriptase enzyme. If reverse transcriptase is blocked, HIV can't make it all the way into the cell, and it doesn't make more copies of itself. It's pretty cool. | 2 |
bs9ebh | Biology | why can’t you suck on a straw after tooth extraction? | The force of the suction could easily remove the clot from the extraction socket exposing the bone which would leave you open to infection but more importantly it could cause post-extraction alveolitis, aka ”dry socket.” Dry socket was by far the worst pain I have ever felt, and I've been ran over with shattered ribs. | 2 |
86h8ky | Physics | Why do watermelons or any fruit for that matter blows up when a bullet passes throught it rather than just leaving an entry to exit hole? | When a projectile passes through a material it is slowed, and that energy has to go somewhere. How projectiles behave on impact is called terminal ballistics. Standard modern projectiles have a lead core with a copper jacket. They are designed to impart as much of their energy as possible to the target, and do so in different ways. Hollow point and soft point bullets used by hunters, police, and for civilian self-defense have a copper jacket that does not cover the tip, and are designed to expand and flatten on impact so they create a larger wound channel and impart most of their energy to the target. Military projectiles are required to have a full copper jacket (FMJ- full metal jacket) by international law. That means the bullets retain their shape better, but in the case of very high energy cartridges like the 30-06 or the 7.62x51mm NATO the bullet is so big and fast that it doesn't matter if much of the energy is lost. With the 5.56x45mm NATO you have a much smaller, lighter projectile at high velocity; less energy, but it tends to break apart, tumble, or yaw on impact transferring a lot of its energy. | 5 |
5wwqcj | Technology | How was it decided that clocks move "clockwise"? | The way the shadow moves on sundials in the northern hemisphere. That's really all there is to it. People were used to reading sundials, so when clocks were invented, it was a natural choice for the hands to move in the same direction as the sun's shadow. | 1 |
o5f7as | Biology | How does fat gain/loss actually work? It’s my understanding that most fat (re: loss) is essentially metabolized and exhaled as carbon dioxide. What I can’t wrap my brain around is that even after eating a calorie surplus the weight doesn’t INSTANTLY appear - maybe after a heavy meal, but if it’s something just really calorie dense this isn’t the case. But the calories have been consumed so I don’t understand why the weight doesn’t reflect that instantly. So it seems like the fat gain side of thing might be actual magic. | Your body isn't 100% efficient at metabolizing calories. Calories are locked up in the food you eat. Some foods are easier to digest than others. Sugar for instance is extremely easy to digest and largely is absorbed straight through the stomach lining rather than going through the digestive system. When you eat something like a chocolate bar, you get a huge energy boost followed by an immediate energy crash as all that energy is made available all at once. Other foods, like green beans, are much more work to digest. The calories are there but they're only gradually released as your digestive system does its work. That chocolate bar can be processed in minutes while a healthy and diverse meal can take 36 hours or even more to fully digest. And the process to turn non-fatty calories into fat also takes time. Your liver has to do work to convert things like carbs and protein calories into fat. So part of it is that you can eat something and simply excrete some of those calories again before your body unlocked them during the digestive process. Part of it is that some calories are much easier to unlock and use (or store) than others. And part of it is timing. If you have a good meal and then later enjoy some exercise, those calories are more likely to be put to use than stored. If you gorge on food and then go to sleep, those calories are likely to go straight into storage. If you eat a chocolate bar, you basically eat an energy bomb so big that you're unlikely to use up all that immediately available energy and it'll get shunted into storage. And since all that energy is made available at once, you'll likely be hungry again soon after and eat something else. Which prevents you from using that stored energy. If you eat green beans, that energy is unlocked gradually and you get plenty of time to use it instead of storing it. And since your body is busy gradually digesting it, you won't feel nearly as hungry. | 2 |
js2k4q | Other | why does the government have to get involved in marriage? | It doesn't *have* to. However, people decided a few hundred years ago (actually way longer but whatever) that it should. Since marriage in a legal sense is fairly financially beneficial, people don't really want the government to suddenly stop being involved (and thus stop providing these benefits). | 6 |
7yoaie | Technology | How do movies get that distinctly "movie" look from the cameras? I don't think it's solely because the cameras are extremely high quality, and I can't seem to think of a way anyone could turn a video into something that just "feels" like a movie | There's a lot that goes into it - lighting, sound (most of it replaced these days), camera angles and movements...but also a lot on the back end, with [digital grading]( URL_0 ) and CGI effects. | 24 |
9az2hi | Physics | When exhaling underwater, why does the air go up in loads of smaller bubbles rather than one big bubble? | There are multiple reasons. First of all, you can't exhale that fast. The most important thing is however the surface tension. Water "doesn't like" having big surfaces, so it wants to minimise the surface ot has with the bubble(s). The orb is the 3D body that has the smallest surface compared to its volume, so the water tries to form the big bubble into an orb. It doesn't work because the water is relatively dense and the bubble has high lift, so it brakes into smaller bubbles. However, in theory, if you somehow generate a huge, perfectly round air bubble, it will stay together. | 1 |
hm3iub | Physics | Do we know if stuff at the planck level are really moving or just working like pixels on a monitor? In a bigger context; When you move your arm around, does it physically move (atoms, cells) or do you just pass the information from planck lenght to plank lenght and it seems like motion. Also an example; Imagine you are in a video on a screen and you move left, you are still you but only the pixels turn on or off. And only your information is passing to the other pixel. Transform the monitor and pixels to the fabric of space. | The Planck scale is not like pixels on a monitor, that is just nothing but a common misconception. The Planck scale is just the scale at which quantum gravity effects become important. These are unkown effects when both gravity and quantum mechanics become important, for which we currently don't have a functioning theory. | 3 |
gjia2j | Biology | Why can we sometimes sense when someone is watching us behind our backs? | We can't actually sense when someone is watching us. It's just a subconscious feeling that usually comes when your brain thinks you might in danger after analysing your environment. It's most likely an evolutionary thing as this feeling increases alertness and therefore your chances of survival in the wild. | 7 |
acljyr | Other | How do pictures like the Mona Lisa and Uncle Sam work so that they are always looking at you no matter the angle? | If a picture were three dimensional, they would only be looking in one direction. Look at a statue. A picture is 2-dimensional. In a picture things don't shift around (parallax) when you move side to side. The painter painted it to look at you. Moving around doesn't cause anything to move relative to anything else. | 2 |
6b7pkd | Other | Why do we not come across dinosaur fossils/bones more often? You'd think with the vast amounts of construction and onsite excavation that we might come across large fossils more often. | Fossils require fairly specific conditions to be created. Not every dead animal will leave fossils. And bones deteriorate back to nature if the conditions the become fossils aren't met and if animals don't get to them. It's why highly populated ecosystems like the rainforest aren't littered with the bones of thousands of animals. | 2 |
o6pi2u | Earth Science | why is the western United States so much more geographically diverse/interesting than the east? The west has deserts, forests with taller trees, and taller mountains, whereas the east has mostly just plains and forests. Why? | The North American Continent is very slowly moving westward because of continental drift. That caused the Rocky mountains to form, and it's those mountains that charge the weather from sunny and warm at the coast, to rain forests, to tall frozen mountains, to plateaus and deserts, and then eventually to the open plains. The east has the Appalachian Mountains which were formed in roughly the same way but they have been eroded away by millions of years of erosion. | 4 |
6qk1ef | Culture | How did "lucifer", which means "lightbringer" in Latin, become one of the names associated with Satan? | 2 Corinthians 11: > 13 For such are false apostles, deceitful workers, transforming themselves into the apostles of Christ. > 14 And no marvel; **for Satan himself is transformed into an angel of light**. > 15 Therefore it is no great thing if **his ministers also be transformed as the ministers of righteousness**; whose end shall be according to their works. | 9 |
fedhd3 | Chemistry | If white is the product of all colors, does that mean if I had a crayon of every color and mixed them all together I would get white? | No. It means that if you shine lights of every colour on a surface that reflects all colours equally you get white. Crayons (generally) don't emit light; they absorb light of certain colours leaving behind just the one they appear as. Mixing them at just the right ratio will result in a grey which may or may not be dark enough to appear black. | 3 |
6j33vy | Technology | Why has there been a surge in robocalls recently? | - The technology got cheaper. - The change in administration means that the regulations are probably not being enforced. - The president fired _lots_ of the FTC, DOJ, and FCC and the other regulatory and enforcement bodies, so there's literally nobody to investigate and prosecute the offenders. - With no replacements even suggested to fill the roles, the probability of getting someone through the congressional vetting process and hired into the jobs before the statue of limitations on the current offenses runs out is "Extremely Low". So welcome to deregulation. (Start Rant) Keep in mind that I am teh olde, I was alive for the passage of the clean air and water acts, I remember the burning rivers and brown skies. I was also alive before the robocall technology was invented. I remember how it was in those first few years before the regulations. So This is the Libertarian Ideal... do away with the laws that make life livable and let "business" do whatever it can get away with... its anarchy everywhere. It _will_ get much worse before the pendulum finishes the swing and starts to swing back. Every eighty or so years we have to re-learn the lessons of the past. So right now we are just "post depression" and we don't have a world war to revitalize our economy, so we've skipped to the fifties where business was king and nobody vaccinates their kids (this time because nobody really remembers Polio) and "'the free market' will protect the environment (was 'the worker' that the free market was going to protect in the fifties, but same thing now as well)." Paying "blacks" a living wage was going to bankrupt the economy because wages would be too high (of course when that was laid to rest the economy boomed because more money was flowing). Basically that thing where "those who refuse to learn from history are doomed to repeat it" is happening right now in spades. If you are middle-ish class then the first signs are going to hit you in your daily utilities; your phone, internet advertising, vehicle repair could be next, who knows. In other classes it's blaming unskilled imagrents for the loss of your skilled job, and blaming the poor instead of your boss even though your (now ex-) boss is the one who fired you and shipped your job overseas. It's part of a giant cycle. The particular nouns get swapped around. "Inter-Racial" was swapped out for "Gay" in the marriage and morality debate. "Illegal Mexicans" was swapped out for "Blacks" in the jobs and civil safety line items. Spam email and spam phone calls were swapped in, in place of door-to-door and direct mail marketing. Eighty years ago the movie industry tried to technologically enforce copyright as a technological problem by using special lenses and non-standard film gauges and gates, now it's encryption and format licenses. So while it may seem like a stretch right now, what you are seeing with the robocalls is the thin, visible edge of the wedge breaking through the regulatory protections from the far side of the legal wall. It goes hand-in-hand with the recent law allowing your ISP to sell your private browsing history. It was strongly presaged by Citizens United and the less obvious Kelo v. City of New London. By convincing the people that their protections were "government overreach", particular moneyed interests have basically broken some key supports in our civil society. And now, for instance, T-Mobile has a deal where my phone says "suspected spam caller" for many numbers. That's a feature they offer (e.g. sell, well include in your service as a selling point). Soon you too will be able to pay, individually, for a feature that used to be part of the regulatory domain provided by government for 1 ten-thousandth the cost. (End Rant) | 10 |
ahu0gh | Other | Can governments just make it a crime to evade vaccinating your children? | It's a very murky area. The First Amendment prevents the government from meddling in affairs of religion, and a lot of these nut bags claim religious grounds for their choices. It's also a very fine line when the government starts legislating your body. If you can force vaccinations, you can force me to do all sorts of things. | 3 |
5s5gfd | Technology | Why is automaton suddenly a big deal? Hasn't it already been happening for a long time? What's different now? | Controls engineer here (the guy programming this stuff). * It got more flexible, so now it's cheaper to change a machine from making product A to making product B. If you were making small batches, changing products annually, or just juggling orders for different parts and you spent most of your time converting your production line, you would automate less. Now your machine automatically adjusts to handle a range of products with inexpensive change parts and actuators. Also, touch screen controls can be reconfigured way easier than buttons and dials. Think fun size candy bars vs regular or king size and Snickers vs Payday; you don't want a dozen different machines that only handle one thing, you want an easily adjusted machine that does all of them. * It got faster. High end automation is working in single digit microsecond reaction times and tens of microseconds for full program/network cycles completely deterministically. Back to candy, if you need 10 lines to fill the world supply of Snickers, that's a bit pricy compared to two that can fill the world supply of Snickers and Payday and have time to cover 100 Grand too. * Motion is way better. CNC is fine and all for hard coding a path for a tool, but multiple levels of electronic camming with profiles calculated on the fly is normal now. Robotics is easy now and when you add machine vision, it replaces anyone that ever picked stuff up on a production line. The tools and program functions to do this stuff exist and are easy and flexible to use (on some automation platforms). * Machine vision exists now. Cameras are better and the software you use to program them is better and more versatile. We aren't checking if the print is good enough for OCR or finding where a pancake is on a conveyor anymore. We're making complex visual analysis. Self driving is whole other level with mixed vision and fucking L~~A~~*I*DAR. * It costs less now. To the point there are clear ROI for all but the most complex, low-skill work. I see people doing things they think are just too hard or expensive to automate (driving is a good analogy here) all the time... While I install and test their replacement that will pay for itself in 6 months. Basically, the limit to automating everything is time to figure out and write the program; mechanically, humans are pretty easy to replace and processor speeds are no object. EDIT: *LIDAR, I'm in machine/process automation, not self driving or defense. I just assumed they replaced "radio" with "laser", but apparently it's "light", resulting in LIDAR instead of LADAR. | 51 |
gmdet2 | Other | If a spaceship could keep going one direction, is there an "end" to the universe like a wall? | Whats outside the 'known universe' is the subject of many debates in many fields - physics, quantum physics, philosophy. Basically no one knows. | 9 |
ijldo4 | Other | On a two lane highway during construction, barrels are often placed on large stretches blocking lanes for months with no actual construction going on in sight. Why is this? | i skimmed and didn't see it mentioned: Often, roadwork is done at night when possible to reduce the impact on traffic and daily life - it takes a fair bit of space to do things safely. Sometimes when building roads, they have to build or install structures beneath them as well, so it can appear as if nothing is happening if you don't know what to look for. Add in that often, physically, things *aren't* happening because of bureaucracy and accounting? it really can take months. Not the be-all-end-all answer, but another factor or two to consider. | 14 |
jlggbg | Biology | Why is it so easy for to remember songs, whereas it's harder to remember things taught in school? I can recall almost every single aspect of how a song sounds: its lyrics, beat, melody, etc. even if I haven't heard the song in a few months. However, when I try to recall concepts that were taught in school a few months ago, such as mathematical formulas, I tend to draw a blank. Is there any specific reason for this? | Our brains remember shapes and patterns. Do you remember ROYGBIV or PEMDAS or The Pledge of Allegiance? Well these use mnemonic techniques to help you remember things. So if you can think of a mnemonic device for a math formula it will help you remember it. | 1 |
77dexz | Other | Why is it, that when there’s a spot on a mirror, there seems to be a gap between it and its own reflection? I’ve always thought about mirrors having a reflective surface, but not a reflective depth? ( if that makes any sense). What is this gap anyway? | The reflective material is on the back of the glass plate so you are seeing the distance between the front of the glass and the reflective material. | 3 |
ci63if | Other | Traditional arabic/north african clothing involves multiple layers of cloth, often black and it usually cover most of the skin. How do the survive in 50°C desert, how do they keep cool? Non native speaker here, I hope you understand my question. | Specifically because they are using multiple layers of cloth and cover most of their bodies. Having multiple layers means that they are trapping pockets of air between the layers and that acts as insulation that helps to keep the heat out. The layer closest to the body also helps keep sweat near the body and slows its evaporation which actually helps to keep things a bit more stable and helps the natural cooling method from said evaporation to be more efficient. They also stay in the shade of their tents and houses during the hottest parts of the day. | 4 |
hmvgsv | Other | Why can you hear say, soda bubbles popping in a can or appliances humming, but not the TV when you're sitting 6 feet away? edited to add that this isn't just a me thing, I've heard a lot of other people say the same thing, to the extent that people make memes about this exact situation. so maybe you can hear the humming of your fridge in the kitchen, but have to watch TV with the subtitles because even if the volume is at a reasonable level it still seems hard to hear? | Speech is a complicated system of sounds, while the humming of a fridge is just mmmmmmmmmmm. In the case of the fridge, you could hear a ^^mmm or a MMMMM and you would still understand it, because it's a simple sound. You do hear what is on TV, the problem is that speech is so complex that you have to understand every single tiny detail clearly in order to get the message. Some sounds are harder to identify than others, so the TV must be extra loud for you to understand what is being said. You are used to the volume of a conversation though, so you don't really notice it. For an analogy, imagine two billboards. One is painted all red, while the other is filled with tiny words. You can see the red billboard from far away, right? Well, you can also see the second billboard, you just can't make out all the details, so you have to get closer. | 1 |
hdbyo9 | Technology | Why does the shuffle function on all of my music libraries always seem to play a select few songs often and the rest of the songs are played sparingly? | Some music players give priority to songs it deems "favorites", based on number of plays. Any song in your shuffle list that you've played more often is likely to get played more often, which in turn reinforces the apps idea that you want it played more often | 2 |