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8es405 | Physics | How can spaceships reenter the earths atmosphere and land even though the earth is spinning at 1674 km/h? | That is only the speed at the equator. The rotational speeds at the poles is 0 and the speed in between varies with the latitude. The absolute rotational speed of the earth is not relevant for a if a spaceship can enter and survive a reentry. The important part is the relative speed of the spacecraft relative to the atmosphere. Airplanes can fly both at the poles and the equator because their speed is relative to the atmosphere. The speed the earth rotate is relative slow compared to the speed you need to have to stay in orbit. The orbital speed at ISS is 7.67 km/s . 1674km/h is only 0.465km/s so you speed is 16 times faste the the rotational speed of the Earth. So the rotational speed of the earth is quite small compared to the orbital speed. You orbit the same way as the earth rotate so the rotational speed so you sped relative to it is lower then the orbital speed. A simpler way to calculate it is that a orbital period is 92 minutes. So 24*60/92= 15.65 orbits per day. So your relative speed to the atmosphere is 7.2 km/s because you travel around it the same way the earth rotate. You land by deaccelerating so you orbit intersect the atmosphere. Then you use the atmosphere to deaccelerate the spacecraft while you are protected by a heat shield. So the spinning of the earth is not that relevant for for your landing and if you travel the same way a faster rotation result in that you need to deaccelerate less the if it was stationary. | 3 |
f4ub8t | Chemistry | What is dust? | The composition varies hugely depending on where you are and...Well...What it's made of. Around a normal house it will be generally a combination of clothing fibers, carpet fibers, pet hair and skin, probably a bit of soil and plant debris. But the majority of it, on average around 80% is...shed human skin cells. So the next time you don't feel like dusting remember that means you're happy with every surface in your house being covered with a thin layer of human flesh. | 2 |
6okuwk | Chemistry | Why do cast iron pots and pans hold their heat so much longer than other cooking materials? | Because they're heavy. Heavy, thick metal will hold heat much longer than thin, light aluminium or copper. | 1 |
jej550 | Biology | Why do we suddenly get really hot So when im out on a brisk walk or coming home and carrying heavy bags, I feel warml when im outside but the moment I get indoors I suddenly get a hot flash. Sometimes I have to run to the bathroom and completely strip to feel some cool air so I don't pass out | I've never had that happen or heard of that happening to anyone I know. Sounds unusual. I'd definitely talk to a doctor. | 5 |
nopklw | Biology | How do Antidepressants work? | There are a whole ton of medications and kinds of antidepressants if you include off-label use, but the general types are SSRIs (selective serotonin reuptake inhibitors) and MAOIs (monoamine oxidase inhibitors). Their actions can be complicated, probably too complex for an ELI5, but they change the way that neurochemicals operate in the brain. SSRIs help to increase and then maintain serotonin levels in the brain. MAOIs lower the production of monoamine oxidase, which operates to lower serotonin, dopamine and norepinephrine in the brain. By lowering the monoamine oxidase, you increase the levels of the neurochemicals it acts on just because there's less of the monoamine oxidase to reduce them. | 4 |
hebip3 | Other | How can a country of America's size only have 2 candidates running when they have an election? | There are many candidates, not just two. However, we hold a series of primary elections to reduce the number of candidates to just one per party, then hold a final election. This year we had [29 candidates]( URL_1 ) run in the democratic primaries. There are many ways to hold elections, and having a series of elections to reduce the number of candidates before the final election is not undemocratic. When many of the candidates are similar, it is helpful to have a way to reduce the number of candidates. Otherwise all of the similar candidates divide up the votes of their supporters, diluting their votes. The electoral college was designed in the 1780s. At that time the states that make up the United States viewed themselves as independent countries that we coming together to form a union. Much like the European union is made up of independent countries. Each state, regardless of population, wanted some say in who would be president. The system gave each state 1 vote for each senator and representative they have. Each state has 2 senators, and a number of representatives proportional to their population. As you can see this was a compromise, giving some power even to less populous states, and more power to more populous states. Designing a government always involves compromises. We call it a democracy because it is. The people vote, and those votes determine the government. No system of voting is perfect. In fact, if you write down a set of goals for your system of voting you can mathematically prove that if you list a few obviously good characteristics of a voting system, no system can satisfy them all unless there are only two choices. See [Arrow's Theorem for Voting Procedures]( URL_0 ). Clearly there are better systems than the one we use, but that does not make ours something other than a democracy. Until 2000 there had only been one election where the winner of the popular vote did not win the presidency. IMHO far bigger problems than our archaic voting rules are the systematic and malicious use of disinformation and lies in campaigning and governing, the unlimited untraceable money behind that disinformation, and the deliberate attempt by politicians and advocacy groups to polarize the electorate instead of attempting to unite or compromise. | 11 |
7z8ijh | Technology | Why do pictures of a computer screen look much different than real life? | Other people have given good explanations for a lot of the reasons so I won't repeat them, but another major difference is dynamic range. This is the ratio of the brightest to darkest shades. To put it in practical terms, if you are in a park on a sunny day, you could see the bright blue sky and at the same time see a bench in the shadow of a tree. If you took a picture of that same scene, you would have to choose which one would be properly exposed in the photo. If you wanted to get the bright blue sky, the shadow would be totally black and you wouldn't be able to see the bench. If you wanted to get the bench in the shadow, the sky would be totally white. Cameras are actually getting pretty good at capturing wide dynamic range, but screens are still far behind, only being able to display a pretty small dynamic range. Even when you compensate for this with HDR (High Dynamic Range) photo processing, it still doesn't look like reality because it is only an approximation. The highlights are darker than they should be and the shadows are lighter. | 17 |
m1yn2x | Biology | When you get a shot in the arm, how can you be sure the contents are being released into a blood vessel? When you donate blood the needle goes into a large, visible vein in your arm or hand but when getting a shot the needle just goes somewhere in your arm. | Man sometimes I forget how American heavy the lingo on Reddit is I was like shot in the arm? Like with a bullet? Then I realised he’s talking about injections | 19 |
n6tb2h | Other | How does 911 tell the difference between prank calls and legit calls? | 911 dispatcher for two small Massachusetts towns here. There is a statistic that something like every 300th call is an actual emergency. We are taught to treat every call as if it is an actual emergency because you do not want to get complacent. Some towns even have policies that they must respond to every 911 call, even if the person on the line says it is accidental, and that they don't actually need anything. Long story short, at least for me, I treat every call as real, until the police officers tell me it isn't. This is also why swatting is a scary concept to me. | 4 |
7h2w9v | Economics | What specifically is so bad about the tax bill passed by the senate? | It's almost 500 pages long. Literally nobody voting on it had time to actually read through the whole thing. They voted on something that literally had hand-written notes on the margins of pages. | 3 |
b854yu | Biology | Why and how do ears start ringing out of the blue? | Tinnitus is constant ringing - what you describe is different. I've been told it's when one of the hearing follicles dies off. | 3 |
9jsla0 | Technology | Trans Atlantic calls in the early 1900s Watching darkest hour. I dont know why I never thought of it before. How did they talk on the phone trans Atlantic back then? I know it was only for the super elite and world leaders. It just seems to me that in those early days it had to be a hardwired grid. | The earliest transatlantic cable was completed in 1858. So yes, it was a hardwired connection. But guess what? It still is! The vast majority of communication still occurs over landlines so you calls today go over such cables. | 1 |
hfx5en | Other | Trading in car for a cheaper car | So, you don’t own the car outright. Let’s say you bought a car for $15,000. You have paid $7,500 on it, and still owe $7,500. The car’s trade in value is $10,000. The other car is for sale for $5,000. So what happens is, the dealer pays you the $10,000 for your car. You use that money to pay off the balance. So now you have $2,500 left over. That’s yours to apply to the cost of the new car. So you’re clearing your old debt and buying the $5,000 car for $2,500. If you didn’t owe anything on the car, you’d get the cheaper car, paid in full plus the difference in cash. | 1 |
9uno1s | Biology | What is that good sensation right before you sneeze and what triggers it? | Though a five-year-old probably shouldn’t know what an orgasm is I believe sneezing is related to the mechanism of orgasm. The phases seem to be similar in that there is a stimulus, That creates an arousal state in either the genitals or in the nasal passage which will eventually reach a threshold trigger that sets off the expulsive reaction. The human body and all animal bodies are very conservative with resources and I’m sure they would utilize very similar mechanisms to do similar jobs, in this case clearing material quickly. So that good feeling right before you sneeze it’s probably very similar to the good feeling you feel immediately before orgasm. | 4 |
62q9kd | Culture | at what point did humans come up with the concepts of first and last names? What was the purpose of last names, since many others shares the same last names as each other? | I'm going to add to this. Blacksmiths were not the only smiths, and they didn't necessarily get the name 'Smith'. Blacksmiths also got the name 'black ', and Brownsmiths got the name ' brown '. Silversmiths and goldsmiths and a host of other smiths probably got the same naming. | 9 |
74mf7f | Other | What do people find uniquely rewarding about listening to live music that they don't get from recorded music? What is cognitively or emotionally different about the experience? | Being there live, you get to experience the energy of the crowd. That alone changes everything. | 4 |
6089fk | Culture | Why does the president of the US need so much more security procedures than many other presidents of the world? Why is the US President considered more at risk of an attack? | The U.S. President is both head of state and head of government. They are a national-level politician who represents their own views rather than being a local-level politician who represents the views of the party and their own district. This focuses the power of the government on a single individual in a way that doesn't apply to most heads of government. Killing the U.S. President not only is an assault on the government of the U.S., but it can create radical shifts in policy. In contrast, most other developed democracies have a parliamentary system where the head of government is simply a member of the leading party/coalition in the legislature. If you assassinate Theresa May, you aren't killing the individual who represents the nation in the people's mind (that's the Queen, who is the head of state). All you're doing is killing the MP from Maidenhead. Before her seat is cold, some other nearly-as-prominent Conservative MP would take her place and the government would continue as before. While U.S.-style executive branches do exist elsewhere, they're primarily in relatively unimportant (in terms of international clout) places. | 2 |
9gohpe | Chemistry | How come if I freeze yogurt it doesn't taste the same as frozen yogurt products? | Because froyo is not that different than ice cream. Tons of sugar and flavoring. It's the same reason you can't just freeze milk and get ice cream. | 4 |
o0sllv | Biology | How exactly does a bee hive work, and how does the honey production cycle work? | Bees live in a beehive, mostly workers and one queen. The queen lays eggs in honeycomb cells in the center of the hive. The outer areas are filled with pollen, nectar, and honey. Pollen and nectar are collected by the worker bees from flowers. Honey is created when a worker drinks honey in a second stomach and starts digesting it. They they spit the honey into a honeycomb cell and fan it so that the water starts evaporating. Once enough water has evaporated, they cap the cell to store it for later. This is what gets collected by beekeepers to process and sell. | 2 |
g6u1d6 | Economics | would it be possible for NY and California to be it's own country (i.e. seperate away from the U.S.). If so, how? If not, why not? | There are much smaller countries than either of these, so yes, it would be possible. It would require the citizens of NY or California to want to leave the U.S., and for the U.S. to let them go, which is extremely unlikely. | 1 |
h7jwsz | Technology | Why is Adobe Flash so insecure? It seems like every other day there is an update for Adobe Flash and it’s security related. Why is this? | A lot of replies and comments here are correct, but there's also a lot of misinformation being repeated, so I'd like to contribute my two cents. Flash was originally created as a vector animation player that could be embedded in websites. It actually went through several versions before a scripting language was added at all (version 4 IIRC), and even then it could only jump around the pre-made animation. Shockwave was introduced well after Flash. I believe that it started as an app for making more advanced, stand-alone software for desktops (at least it certainly had this capability, while Flash has always been only for browsers), but a browser plug-in was soon made to be a successor to Flash. However, Flash already had significant momentum by this point, and Macromedia ended up just bringing more and more features over from Shockwave into Flash. Up to and including version 8, it was possible to download the complete Flash file format specification from Macromedia/Adobe. This was a part of their business plan for Flash. Anyway, by reading the specification, you could see all the ins and outs of how ActionScript (Flash's internal scripting language) was supposed to work. And unless something changed massively since then (I would bet that it hasn't), it *should* have been possible to make a Flash player executable that ran relatively securely. I need to talk a bit about how programs actually work, and make a very simplified distinction. Several comments in this thread talk about "programs" like a program is a program is a program, and any program can do anything. This is not the case. The comments about Flash programs "escaping", or "getting outside" the browser are especially jarring. There are many ways to categorise different types of program, but I'm just going to break it down into "native" and "interpreted". There is more to it than that, but this is ELI5, not an undergrad comp. sci. course. A native program is one which has been created to run on one particular type of hardware (and probably in concert with some firmware or OS). Native programs generally have access to the entire system, at least in theory. In practice, there are a lot of techniques to make native programs ask permission before they do certain things, and to effectively block the program from overriding that permission. While the Flash player itself is a native program, the ActionScript program contained in a Flash animation file is not native, but interpreted. An Interpreted program is one which must be run through another program (usually a native program), in order to execute, rather than executing directly on the hardware. There are plenty of advantages to this, along with some disadvantages, which is why we still have both types of program (although I would argue that the line gets more blurred every day). As an example, JavaScript (ECMAScript) is probably the most popular interpreted language in the world today. Let's imagine that our programs are people working in a kitchen. The native program is a regular person. They can walk around the kitchen at will. They can pick up and attempt to use any implement or piece of equipment. They're free to do anything, which gives them great capabilities, but also makes them potentially very dangerous. So the kitchen designer (hardware architects) put strong safety guards on some of the equipment, and locks on other things. Only the head chef (the OS/firmware) has the keys, because they got there first thing in the morning to open the restaurant (booted before any other software). The interpreted program isn't really even in the kitchen. For Flash, the Flash player executable is there, working in the kitchen. But the ActionScript program contained in a downloaded Flash file is like someone else talking to them over the phone, and asking them to do things. The problem with this situation is that the Flash player is fairly dumb. Flash started off accepting requests like, "scramble some eggs" or "bake a dozen chocolate-chip cookies", which are harmless enough. But as it developed, the potential commands became less abstract and more detailed, like "fill a pot with water" or "cut the thing on the cutting board into 10 equal segments". The Flash executable can avoid some problems, like it knows not to put anything but food on the cutting board, or pick up a hot pot with bare hands, but that's not "common sense", just a long list of individual rules. When potential requests got to the point of "turn your wrist 45 degrees" or "take two paces to your right", things started to get ugly. Flash knew to ignore "block the sink and flood the kitchen", but it would happily "boil a pot of pasta", then "empty the pot into the sink", and finally "turn on the faucet 100%". That is, until the authors of Flash heard about this latest exploit and released an update that made the Flash executable check the drain in the sink before turning on the faucet. A lot of the time, the head chef (OS/firmware) or their first assistant (anti-virus/anti-malware software) will notice what is happening and stop the Flash executable from wrecking the kitchen or injuring anyone but themselves, but there's only so much you can do to stop a truly malicious attacker without making life hard for others. And sometimes, someone would figure out something like, "pick up a knife", "raise your arm above your head", "put your arm straight out in front of you", "take one step forward", "repeat until the number of other people in the kitchen equals zero". I wasn't a developer for the Flash software, but I think that the problem with it was, as others in this thread have said, that it was first developed with a somewhat naive outlook. A simple list of "do not do these" items was sufficient to stop honest programmers from getting themselves into trouble. But as Flash became more powerful, and more universal (attracting more malicious programmers), it seemed like they just kept adding to that list of individual rules, rather than reworking the software to keep better track of its environment as a whole, which would've been a significant investment of labour for negligible immediate return. | 12 |
hvzirm | Biology | What benefit does a reptile have by being cold blooded? | It doesn’t need to waste energy keeping its body temperature at a certain level. It can survive a lot longer in cold temperatures since it can use that energy for the important mechanisms. | 5 |
98nf27 | Biology | female voices are higher pitch than male voices, so why can you still hear the difference between a male and female voice when they sing the exact same note for example? | Basically the frequency response of the resonant cavity - chest/throat/mouth is different between persons - and between male and female and short-sized and full sized adults. When humans makes sounds, you cant judge them from their whistling sound or their fricative sounds - the 't', 'sh' sounds etc. What gives them away is when the glottal folds in their throat starts clicking - ie when they speak with their vocal cords. The clicks resonate, and the sound that emanates is the sum of the responses of each click - much like if you start clapping in a resonant room. What can also give people away is if they cough - then too you can roughly identify the person - here a noisy impulse is injected and converted by the resonant cavity. You can record the sound of a clap and the resultant sound to characterize the room. Similarly a click of vocal folds. When a prototypical male sings vs a prototypical female sing the same note, the proportion of how much of each frequenc component they have will be different. For example for a small-sized person, with a shorter chest cavity, the resonant frequency of the cavity maybe a bit higher. | 17 |
8iv66c | Biology | I’m shortsighted and my eyes get worse every year. What actually happens to my eyes to cause my sight to deteriorate? | Your eyeballs are getting longer. Lens farther away from the retina makes you near/short sighted. Dunno why. | 12 |
83pwyv | Other | Why is there little to no market for Native Ameican food? | Regardless of the answers that may come up about the "market" for native American foods. I'd like to point out a [great older thread]( URL_0 ) from /r/AskHistorians that talks about native american foods that may show you, that there is a whole lot of market for it... its just foods we don't necessarily associate with being native american , but actually have their foundations in native american cuisine. | 2 |
krhjqs | Biology | Why did people start bathing every day? | Because you will smell if you don't bathe regularly. Don't listen to the people who say "but I don't smell and I only shower once a week." Yes, they do smell, they're just used to it. I wouldn't say showering literally every day is necessary (unless you workout and start sweating), but every other day at minimum. Furthermore, sex is much better when stuff doesn't smell (for both sexes.) | 3 |
dfr89f | Other | How come when Japanese people speak English, they pronounce "R"s as "L"s but when saying a name that has an R, it doesn't happen? Only example I can give off the top of my head is from an anime, Sword Art Online, where they normally say Kirito without any problem. | So, Japanese as a language doesn't have an "R" sound. It doesn't have an "L" sound. It instead has a sound that is somewhat in the middle of both of those, with a little bit of "D" mixed in. If you grew up only speaking Japanese, you aren't going to be able to fully grasp the sounds of "R" and "L" being different, as you weren't raised with those sounds in your life. | 1 |
5xlzr5 | Other | Why is it when you pour water out of some cups, the water drizzles down the underside of the cup rather than pour out normally? Like it sticks to the side of the cup facing down as it pours out. Is it the shape of the cup? | I believe this is caused by the Coandă effect, where flow is seemingly attracted to surfaces. As the water passes the surface of the container a portion of it is slowed down by the container. This leads to a lower pressure than the fluid not touching the bottle and as a result the flow changes direction. Edit: Added word | 2 |
5q8gdk | Culture | the case for undocumented students not trying to offend anyone and not gunning for anything political here, honest. just a little confused as to why some universities are willing to aid undocumented students in staying at school? isn't that illegal? how does the government not find and deport these students once they are registered at a university? additionally, why recently has there been a string of people (particularly students) publicly "coming out" as undocumented in published op-eds, social media, etc.? doesn't this endanger these people and their families? | I'll try to answer your questions as best I can here. 1. Universities are willing to provide "aid" to undocumented students because that's what they are, institutions of higher education. They see the value in a diverse student population. Most of the western states provide instate tuition to undocumented students in they attended high school in the state also, now this does not mean that they receive financial aid, that has to be through a private scholarship or they have to pay everything themselves. So at the end it all comes down to merit, and who wants it more. 2. Is it illegal ? No, and a lot of this comes down to state rights. Universities are schools and not ICE. If there was a law requiring them to turn over students than it would be illegal, yes. 3. People are coming out for the exact reason that you are posting this, to let people know they exist and are not just a talking point for the left or right. To get people talking about it, it's easy to have an opinion on this subject without knowing who is actually affected by this but in fact these undocumented immigrants could be your friend, your neighbor or your co-worker and you would never know unless they spoke out about it. To clarify, I am an undocumented immigrant. Was brought here was I was 7. | 3 |
cyagkp | Biology | why do our bodies tend to automatically wake up earlier than normal after a night of drinking? | From /u/Daniel0909 a few weeks ago: Your body produces an over abundance of insulin to process the carbs/sugars from the alcohol in your blood and ends up over doing it and processing too much. Normally your pancreas would produce glucagon which would prompt your liver to release some glucose back in to the blood stream to balance things out. But enough damage to your liver from frequent alcohol abuse will lower its efficiency and you can easily enter a hypoglycemic state where your body believes it's starving. Now alcohol induced hypoglycemia is basically the polar opposite of being drunk. Imagine waking up from barely being able to hold your eyes open to being just terrified for no reason with your heart trying to beat out of your chest like a machine gun. Extreme anxiety, nervousness and disorientation. You're sweating but you're cold and you're shaking and you have no idea why this is happening. It's also potentially fatal if it's bad enough and you have no idea what's going on. "Functional alcoholism" safely folks! Or... you know... get help and live a happier and more fulfilled life. Whatever, I'm not here. | 11 |
e4mvy5 | Other | Scalpers. How does it work for events that don't even get close to selling out? | The scalpers standing outside already lost their money, you'll get the most money selling it a couple days before, these guys are either selling fake/used tickets or they bought a bunch at a cheaper rate and are just tryna dump em. | 11 |
7zv966 | Culture | Why is Denmark (1 silver medal in Winter Olympics history) so terrible at the Winter Olympics, while its Nordic neighbor Norway, has 367 medals all time? | In the 1984 winter olympics Norway did very bad and the goverment didn't like this. They started "Project 88" as a long term plan to dominate the olympics. It ended up as Olympiatoppen and is now the leading knowledge organisation for training elite athletes in Norway. Norwegian oil-money got invested to train and finance the elite to take over the world during two weeks every other year. URL_0 | 28 |
bfotoz | Biology | Why are people now so much taller than they were hundreds of years ago? | What about natural selection, or is it artificial if it's done by humans?, anyways, if taller individuals are favoured and mate more, have more offspring and all that wouldn't that have a bigger impact on height than diet that hasn't got any better in the last 20 or 30 years in the developed world and yet people is taller than before? I mean, you can feed all you want a chihuahua but it isn't getting to Grteat Dane size, just because they have been selected for their size for generations, you can starve the Great Dane and it will still outgrow the well fed chihuahua. | 19 |
6t5ayp | Biology | How do you explain a sense to someone who was born physically unable to perceive it? | There was a pretty good scene in the old movie Mask where the main character explains to a blind person what colors and clouds feel like by comparing seeing clouds to touching cotton balls, and something cold is blue, hot is red, etc | 17 |
8tsvyw | Biology | Why we get mini mouth blisters on the inside of our cheeks when eating or sometimes at random I'm not talking about any std - these are small little bubbles that you can pop with your finger fairly easily. | Did you eat something hot and burn your mouth? Maybe a food allergy? | 3 |
66p94r | Other | Why do languages have homonyms? Bat and bat, muñeca and muñeca. I'm sure there are a ton more in all languages, but why? Did we run out of words so we have to start using some twice? Note, this is not homophones, which sound the same (raise, raze, rays), but homonyms, so the exact same word. EDIT: Also, [this is a fun list]( URL_0 ). | Languages aren't invented by a committee of people drawing up a list of possible words and then deciding what meanings to assign to them. So no, we don't "run out of words": languages evolve spontaneously according to rules we can discover, but not according to any conscious logic. As others have pointed out, homonyms just sort of happen, often by coincidence. | 4 |
6j0f4e | Biology | What causes humans' brains to be more developed than other species, when some have much larger brains? | Volume or weight of the brain isn't the key but how many connections each neuron makes with others. | 2 |
85fyg5 | Biology | when someone has a higher alcohol tolerance than someone else, what’s the difference on a molecular level? | It’s more of a cognitive thing than it is molecular. The easiest way to think of it is that when one consumes lots of alcohol lots of times, their body “adjusts” to the present alcohol. When they get sober and get drunk again, their body, having already adapted to the presence of the alcohol, isn’t as affected. This is also a basic way to explain alcohol addiction. When your body adjusts to the alcohol and you happen to be sober, you feel weird. Thus, you feel drawn to drinking to feel “normal” again. | 2 |
e0rfmg | Biology | Why do spicy foods burn on the way out? I'm a huge fan of all things spicy, at least when I eat them. However, whenever I ingest something containing a large amount of capsaicin, I am left with a horrendous burning sensation in my posterior extruder when I defecate. Could someone please explain why this happens uniquely to spicy food? | The mucus membranes in your rectum and colon are just like the ones in your mouth and tongue. They have nerve endings and are sensitive to the capsasin in spicy foods. | 2 |
845c8j | Chemistry | Why Does String Cheese taste better when pulled apart, rather than when just biting into it? | Because when you pull it apart it has a chance to warm up. Cheeses taste better "not cold". Try this next time you want a piece of string cheese: take it out of your fridge and put it in your pocket for a couple minutes before you eat it. Don't forget the string cheese in your pocket. **Do not forget the string cheese in your pocket**. | 2 |
ize440 | Biology | Why do we have to work out to gain muscles? Why being ripped isn't just the "default" state of humans, like having two eyes? | Our bodies don't like being huge by default. Being really large means you have to eat a lot more to maintain that size, and until relatively recently in human history, getting enough food to survive was difficult for the majority of the human race, let alone getting enough food to have MASSIVE GAINS. So our bodies only build excess muscle if forced to, if pushed into situations where the muscles are exercised to the point of exhaustion and then grow more muscle mass to try and keep up. The other part about being ripped is having a low body fat level, which makes the muscles more visible. Our bodies store fat to use in case of famines, and are really good at that, because we evolved to survive in situations where there isn't enough food to eat. So if there is a lot of extra food, we store it as fat. Which means that our bodies don't like being so lean that our muscles are visible and you can see the abs, they like storing extra food as fat in case of emergencies. Because our bodies are still in "We are cavemen who might have to hunt a mammoth to survive the cruel harsh ice age winter" mode, and haven't adapted to the fact that many of us can just go to a store and get way more food than we'll ever need. tl;dr - Our bodies are still in caveman mode, optimized for surviving famine, rather than being bodybuilders. | 1 |
kc005v | Chemistry | Why is cling film so sticky when it touches itself or around bowls but it does not feel sticky at all when it touches our hands? | Materials can be classified according to how well they hold on to charge. Metals have free electrons that are shared among the atoms and can move with very little electric field. These are conductors. Other materials hold on to their electrons and require work (energy) to remove them. They will not move just because a weak electric field (force per charge) exists. These are insulators. Among electric insulators, these materials can be further classified according to how well they hold on to their electrons. This is known as the triboelectric series. You can look this up and see which two materials from this series will hold on to electrons more. Rubbing one material against another will jostle electrons free. The material closer to the negative side (the better insulator) will end up with a net gain of electrons. These two materials will cling because of a further induced effect that will push on one charge and pull on the opposite charge. This series can explain why pvc is often used as insulating material for wires. Your science teacher may have rubbed rubber with fur. These two are far apart on the series with the rubber gaining substantial net electrons. Paired with this demonstration is usually silk with a glass rod. But here, the silk is the one gaining the electrons from the glass. This effect is less pronounced than the first pair as silk and glass are much closer in their electron holding strength. This is like rubbing a balloon on your hair and sticking the balloon to a wall. But here the wall was never rubbed and has no net charge. Uncharged insulators can stick to charged insulators when a charge polarization is induced. The balloon netted more electrons from those jostled free by rubbing your hair. Your hair stands up because it has a net charge as well, but positive due to lack of electrons. The balloon has extra charge clumped near where they were pulled by rubbing on your hair and when brought near a wall (an insulator), it will push electrons in the wall away a little (reducing the repulsion) and then feel an attractive force because of this induced polarization (alignment of electrons further from the balloon than they were before). So saran wrap or cling wrap is very far on the negative side of this series. So much so, that these materials often stick to themselves because of the effect mentioned above. Rubbing cling wrap very vigorously against itself may jostle some electrons free, but an equal amount will go to each side, so this is not from rubbing. The effect works best with materials paired from the far opposite end of the triboelectric series. These still need to be insulators. Remember that a conductor under the influence of an electric field will simply react to the field by free electrons moving until the force on them is balanced. So pair cling wrap with glass. Glass will hold on to its electrons, but they will respond more and produce that induced polarization to the greatest degree possible and thus produce the greatest clinging attractive force. Your skin will not show up on most series lists, but you can expect that it would fall around wood, cotton, or perhaps hair or fur if dry. There are also far too many dissolved ions in your body that can react to this force and so it acts somewhat like a metal so there would be no effect. | 6 |
7ziu0o | Biology | Does it take more energy to run with 4 legs than it does 2? Good morning all (From Aus) Hoping someone can sort out this argument that I had with my housemate last night: When a 4 legged animal runs, are they exerting more energy than a human? My argument is that x weight is propelled by 4 legs would be x/4 compared to a human weight y is propelled by 2 legs, hence x/2. The animal will have less muscles than a human but that is generally related to their size and weight. I don't think that we can do a muscle comparison between humans and animals for this as structural support are included with running, but aren't weight bearing or used to move. Hoping for some good answers! Cheers | Efficiency depends on the animal, actually. Animals that run all the time, horses and deer for example, have tendons in their legs that act like bouncy springs, conserving quite a bit of energy. On the other hand, bears for example, lots of muscles in their limbs, but more for killing prey and climbing trees, not as efficient at running as a horse. To answer your own question, what takes more energy, running on 4 legs or 2, take an animal that can do both, bear or gorilla for example, and ask yourself do they prefer to run on 2 legs or 4? | 5 |
mzvuy5 | Physics | Is possible to do a water wired computer? I asked to my stepdad if, since the water cunduct electricity, is possible to reduce computers costs by making “water-wires” instead of copper ones. He said that isn’t possible, but I’m not understanding why! He said that electricity travel from - pole to + pole. So why with water doesn’t happen the same?!? | Water doesnt conduct electricity. Impurities in water conducts electricity. Also, as a liquid, even if it did conduct electricity, it wouldn't conduct it in one direction. | 5 |
mvhumv | Biology | How do rats digest solid stuff like plastic, sponges ? | if you're seeing a rat chew through plastic, they likely didn't swallow it, they just chewed it. | 2 |
meshwr | Chemistry | how the eff do magic erasers work so much better than soap and water? Don’t understand how they work so much better. | They work more like sandpaper than detergent. For those who know and might even care, they have a Mohs hardness of around 4 and a grit of 3000-5000 depending (they're not the thing to use if you want precise polishing). | 3 |
9md7qv | Culture | Why is violence and gore more acceptable than sex and nudity? | Yeah, I always get annoyed at how puritan (mostly) US shows are. In Breaking Bad for example. Drugs everywhere, killing and maiming, all ok. Then the cartel gets "the girls" for a party, and I'l supposed to believe that they don't expect them to get naked or at least topless? Every show where they go to a strip club, no nudity. Lucifer was a prime example. Here's the devil, depraved and sex-crazy. But apperently a prude because nobody got naked in his vicinity And also, US censor and movie, tv-makers. Seeing a dick won't make you gay. Watching a Spanish movie now, "the author", and twenty minutes in the main character, an aspiring writer, remembers advice that he needs to write with his balls on the table. So the guy stands up, whips it out in full view and stands there. Balls on the table. | 5 |
8uqbj1 | Biology | Men and Women have the same body temperature, right? Then why does it seem that on average women are always cold and shower at temperatures exceeding the melting point of galvanized steel? | According to CTRL-F, no one in this thread has mentioned testicles yet? Men's testicles are external to their bodies because they require lower than body temperatures to function properly. Seems like an obvious corollary that men should therefore be more comfortable in lower temperatures. Anything close to body temperature will impede their balls from storing piss. | 26 |
702d4u | Biology | When someone claims to have a high tolerance to pain, are they actually tolerating the pain or are their pain receptors less sensitive? I see people claiming to have a high pain tolerance, leading them to neglect medical attention for conditions that would have others calling an ambulance. Are they badass, or actually feeling a lesser degree of pain? | You become conditioned to experience pain differently each time you experience it. You still feel it, unless you have nerve damage, but it doesn't affect you the same. | 13 |
gxytwc | Biology | Why does our own voice sound weird when we hear it | In my opinion, I think it's our body's reaction to hearing a disembodied voice? It sounds weird, but you never sound weird to yourself when you're talking, only when you listen to your voice on a phone or recording. You recognize the voice as yours, but you're not talking, physically. So we just get this forced "out-of-body experience" and we just go "ew" in response. But that's what I think, at least. | 5 |
n2cio4 | Mathematics | How does a folded sheet of paper 42X be the distance to the moon? | if the paper is folded 42 times, then there would be 2^42 (=4,398,046,511,104) layers of paper. Standard office paper is 0.1 mm thick. So 2^42 / 10 = 439 billion mm, / 1000 = 439 million meters, / 1000 = 439,000 kilometers, which roughly matches the 405,000 km to the moon (at the farthest point in its elliptical orbit) Shameless stolen from: URL_0 | 7 |
g7sb2s | Economics | Why would anyone be against universal healthcare? What benefit does alienating the lower/working class do? | I grew up in a military family; my father was an officer in the USAF for the entirety of my childhood and adolescence. Although it is less so today, in the time frame in question (1970 - 1995) the military health care system (provided directly by the branches and through the Veteran's Administration) was essentially a socialized, single-payer system. (There were some non-trivial differentiators between what we had and a politically pure single-payer system - for example, military families were welcome to go off the grid and buy private health care, if they were somehow independently wealthy on a captain's salary.) The system was, on balance, abjectly shitty. Wait times were long. Doctor competence was low. Records handling was appalling. People died, all the time, because the system honestly didn't care whether they lived or died. That is why a lot of people, myself included, are leery of a government-run system. We've seen firsthand what it can easily become. | 5 |
9pfd28 | Physics | How do scientists use lasers to cool particles down to almost absolute zero? Thanks for all the explanations! Super cool (ha) stuff. | In ELI5 terms: * Lasers are composed of light, and all the photons that make up the laser light have the exact same wavelength (color). The energy of each photon is exactly determined by its wavelength (color). * Photons interact with atoms (matter) by being absorbed by the electrons that orbit the nucleus of each atom. When a photon is absorbed by an electron, the photon gives its energy to the electron, and the electron jumps to a higher orbital. The electron orbits there for a while, then jumps back down to its normal orbital, and releases the extra energy in the form of a (different) photon. * Each atom only has certain gaps in its orbitals; there are only a few possible "spots" for its electrons to jump up to and back down from. So the trick is to hit the atoms with a laser that has a color that gives the electrons ALMOST enough energy to jump up to an orbital, but not quite enough. The electrons will absorb the laser photons, and since they need just a little bit more energy, they will borrow it from their own heat / temperature (vibration). This will cool down the atom a little. So the electrons jump up to the orbital, spend some time there, and then release their extra energy in the form of (different color) photons. The electrons don't release any energy as heat. Basically what you see is, you shoot a red (for example) laser at the material that needs to be cooled, and the material absorbs it, cools down in order to have enough energy, and then glows the total energy back as more energetic yellow or green photons, instead of the original (lower energy) red. Your laser puts in red, your material glows yellow, and uses up its own heat, cooling down, in order to make use of the laser energy. | 2 |
90lxcq | Physics | Would the Winchester brothers' rock-salt shotgun actually work? | Depending on how close you are when you are shot, I bet it would still sting a bit. Would like a ghost to confirm | 3 |
ipoo7a | Biology | how psychedlic drugs can treat illnesses like depression when you should only take them while you're in a 'good' state of mind It seems paradox when I read about e.g. LSD or Magic Mushrooms and it says on one side they can be used to treat mental illnesses but on the other side you have to be in a 'healthy' state of mind | If you know what you are doing with LSD, you can take it even when you are not in the greatest state of mind. That's more advice for beginners. I would probably, personally, not advice immediately jumping down the rough road of depression recovery until you have some experience with the drug, but YMMV | 9 |
nuqc0z | Other | Why do antiseptics such as alcohol burn on open wounds? | They mess with the heat detecting cells in your skin, the things that let you know if somethings too hot. it reduces the threshold that sets them off to slightly below your body temperature. So your own body temperature is detected as being hot enough to burn you. | 1 |
ao9ael | Technology | How do “Sleep tanks” work? So recently, an article came out that the [New England Patriots have sleep tanks]( URL_0 ) at Gilette stadium which can simulate 4-5 hours of sleep in just 45 minutes. How does this work? Does our body truly act like it received 4-5 hours or is it all mental? | Most things athletes use to enhance their performance don’t have measurable benefits that would fall outside of the margin of error in a scientific study. A great deal of it is really placebo effect. Some of it actually works, but the benefit is astonishingly small. But remember, these are ELITE athletes. For someone who is a layperson, that tiny advantage won’t make us appreciably better. But with, say 100 elite athletes who are all at the top of their professions, the smallest advantage can have a marked effect on their performance. Even if it doesn’t have an actual benefit, the placebo effect can still make a major mental difference, and a mental edge can be every bit as effective as a physical one. The Freakonomics podcast has done a series on sports and their most recent was on this mental game. Athletes and teams will spend millions chasing a 1% edge. But often times they’ll ignore the data telling them what they should do, even if it gives them a bigger edge, because they don’t want athletes or coaches second guessing themselves ... confidence is such a big factor. | 6 |
jcx89d | Other | How serious of a problem is wasting water through flushing toilets? I've heard flushing toilets wastes water, but how, and how serious of a problem is it? And if it’s serious, why are we still using normal toilets when there seems to already be a lot of prototypes attempting to solve it? | I can only offer a little insight here but, from what know, a lot of toilets use too much water for a simple job. You probably don’t need 5 litres of water to flush pee, for instance. Let’s say you really only need 3 litres for pee. In a city of 5 million people, then that’s 10 million wasted litres of water if everyone only peed once a day, but they don’t. The average is probably more like 5 or 6 times each. Although there are loads of water saving toilet systems, they are expensive to buy and fit, so people do the maths and think “it will cost 300 or whatever to buy and fit, which is a lot of upfront cost for future savings”, so they don’t change until, maybe, they remodel. You can save a ton of water by putting a brick in the tank, or a water bottle, or change the mechanism to allow less water into the tank. Fresh, clean drinking water is often in short supply and water companies moan about us wasting water all the time, while simultaneously allowing millions of litres to be lost through leaks in their own pipes. | 3 |
cjllg1 | Biology | Why do "weeds" grow so much more quickly and without any nurturing compared to plants/crops? | If you really think about it, the only difference between a weed and a plant is whether or not you want it there. | 5 |
huagps | Biology | What causes mental fatigue? I know that all muscles produce lactic acid on stress due to a lack of oxygen, and that's what causes muscular fatigue, but what is the process the creates mental fatigue? | Constant stresses throughout the day can overwhelm a person's ability to process them, especially if left unattended. This is basically a mild form of "Burnout." There is a lot of [scientific research for burnout]( URL_0 ) if you're interested. Basically though, stress can make you tired. There's still a lot of research to do as to why, but here is the leading theory: The brain needs to rest, but stress triggers constant fight/flight responses, so it is unable rest because it is constantly aroused at a neurochemical level. This is also why various forms of brain rest e.g. napping and meditation are often used to prevent mental fatigue and burnout. | 11 |
g5bsa6 | Biology | Do people still sweat while swimming? Sweat helps to expel excess body heat. As the water would essentially be performing that task now, would your body still create sweat? Lets assume water in direct contact with the skin, no wet suits. | /u/SYLOH is right that you still sweat. I just wanted to add that a wet suit still has your body in direct contact with water - that's what makes it a wet suit. The suit is not perfectly sealed, so water gets in. If you want to work in the water without getting wet, you wear a dry suit. | 2 |
hii51q | Other | Why are there constantly fresh stones in a farmers field? I see that each year at the start of the season, the farmer comes with his tractor and ploughs the field. Each year there are more stones to be removed. Why is this possible? Surely eventually there will be no stones. Or is there a little stone leprechaun that comes and plants them each year to be a nuisance? | There must be a constant supply of new stones from the weathering bedrock below. They're pushed to the surface, taking many years. The mechanism is explained in other comments. | 5 |
5sss8k | Technology | Why do livestreams always have a small delay but group calls (on skype for example) don't We can show our screen to everyone who's on the call (on skype) and it doesn't have a delay, then why do livestreams of games, for example, have that delay. Isn't it almost the same thing? | Well, for starters, a video game stream is sending the data to sometimes *hundreds* of viewers (or more), whereas you're just sending data directly to your Skype contacts. In addition, the Skype video is likely nowhere near as high quality as the video game stream. Also, there often *is* a delay - a slight one - when you're using Skype. You just don't really notice it since it's maybe half a second tops. There are streaming sites out there that do have a much shorter delay than many of the mainstream streaming sites, too. | 1 |
7asmmm | Other | When singing why do you sound perfectly in tune to yourself but not to others? | I guess it has to do with psychoacoustics: URL_0 While singing you "hear" the originial voice of the singer in your head. The virtual sound interferes with that of your voice which leads to an "autotuning" effect. | 3 |
8f9irx | Biology | How does alcohol "supercharge" medication? | Depending on the medication alcohol may act as a solvent allowing the medication to enter your bloodstream at an accelerated rate making you high as fuck. | 2 |
atsssf | Biology | Why does it take so long for mood stabilizing drugs such as antidepressants to work? | In the case of antidepressants, it's because their mechanism of action is neurogenesis in the hippocampus. This process takes roughly two weeks to have an effect on serotonin levels. The fact that antidepressants act via hippocampal neurogenesis is relatively recently discovered by science - within about the last ten years. | 5 |
krvuzc | Biology | If mayonnaise is made with raw eggs, how come we do not develop sicknesses or side effects related to this upon consumption? I have just learnt that mayonnaise is made with raw eggs, but how come we do not experience any illnesses as a result? | Commercially made mayo is pasteurized, basically heated for an extended period to sterilize it. | 3 |
eak8wr | Engineering | How do cable lines on telephone poles transmit and receive data along thousands of houses and not get interference? | The interference part of your question. Edit: Actually a different side of it to consider. The other answers already cover the signals interfering with each other. There is a lot of interference. Cracks in cable, bad connectors, faulty hardware and other issues can all lead to signal egress and ingress that can lead to interference with external RF signals from leakage and internal interference from outside sources getting in. These issues increase the amount of signal noise in the system, which essentially makes the signal dirty by reducing the amount of signal above the noise floor (SNR). It is maintained by technicians in the field and an office crew that monitors the plant for those and other issues. The long range work is done almost entirely on fiber-optic cable, but that still requires a lot of work. Fiber splicing is hard work that requires a clean room to prevent dust and other debris from getting inside of the splice and blocking or (even slightly) redirecting the light. With a coax network, every piece of cable, connector, splitter, directional coupler, amplifier, mini-bridger, and literally any other piece of hardware can cause interference. Even electrical issues in homes can cause problems. I can't tell you how many intermittent area outages I've seen that were caused by people using old electronics that were causing interference. Everything has to be perfect, because there is just so much on these networks. Basically, it's done with a lot of work. A lot. The other answers regarding multiplexing and the like should explain the parts that I would have to Google. | 10 |
acxh97 | Other | If babies weren't exposed to any language, would they invent their own common language? | In linguistics, this is called "The Forbidden Experiment" because it would be horrifically cruel. There have been several historical examples of feral children, to varying degrees, who have been raised individually with little or no exposure to language, but not enough to really draw any conclusions beyond it being incredibly damaging to their development. There have also been a few cases of twins who've spoken one-off shared languages (e.g., Poto and Cabengo, and June and Jennifer Gibbons), but not raised entirely without outside language as an influence. | 4 |
gtycqd | Other | Why is the BLM movement burning buildings like the post office when it seems counter active to the cause? | Rioters and mob mentality mostly. The people actually there for the cause aren't the ones doing the destruction. There are several videos showing the organizers actively trying to stop the looting/destruction. Some people may specifically be there to cause mayhem and chaos, but it doesn't define the movement. | 1 |
8y5qm5 | Biology | Why is it risky to eat cookie dough with raw egg when Mayo also has raw egg whites? | Basically because commercially bought mayo uses sterilizing methods to make the eggs safe without cooking them. Besides, chances are that most store bought mayo doesn't even use real eggs. | 3 |
5zx3zu | Culture | Why are baby boomers so hated? I know they got lucky to be born in an age of prosperity, but what did they do to fuck over younger Americans? | "I know they got lucky to be born in an age of prosperity" Okay, two things are wrong with this statement. 1) There was no luck. The world is how it is because of our elders, our forefathers. 2) It was a less prosperous time than now. They just pretended that it was a prosperous time and lived beyond their means. Making purchases in the names of their children and grandchildren. All the hate and vitriol that's being cast upon them is entirely deserved. | 53 |
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) | US Midwest, it's not really as okay as it seems. Most stores will allow it without too much fuss (since we have the 'customer is always right' mantra), but it's still seen as a pretty trashy thing to do, an adult will get subtly looked down upon for doing it. It's usually only done for fussy kids, and more often than not it's punctuated with casual apologies and "it's fine"s when you hit the register. Of course, I worked at a grocery store, so I'm not sure what the big retailer people have to put up with, and it might depend a lot on the store and region in question. | 20 |
8tq7wh | Other | How does hypnotism work? Can it really make someone believe they are a chicken and be switched on and off with a finger snap? | I've been hypnotised on stage as part of a show twice at my university. It's weird, you essentially hypnotise yourself. Your brain is totally active and you keep telling yourself that you could break out of it at any moment if you wanted to, but it's almost like the expectation of all parties involved (you, the hypnotist, the audience etc.) is what keeps you involved with it. What is weird was how the hypnotist says that you can't be hypnotised if you've drank alcohol. The first time I volunteered myself for the show, I had had 2 beers within a few hours before going on stage and the hypnotist said to me after the show that she almost made me sit back down in the audience because it was taking me a little longer to "go under". I distinctly remember not being hypnotised for about as long as it took the little beer buzz to subside. | 2 |
kz3elr | Biology | Why does our stomach start to have intense pain after not eating for a long time? | It's basically just your stomach yelling at you for food. Our bodies aren't very good at communicating with us, the best most parts can do is cause pain as a "something's wrong" signal. Stomachs have a better vocabulary, they've got nausea and hunger pangs as well, but if you ignore those then all that's left is pain signals. It's also worth noting that your stomach is a bit silly and can't actually tell if you need food. It starts saying "I'm hungry" when it means "I haven't eaten in a while" or "don't I usually get some food about now", and it'll start hurting as if to say "we're starving to death" when what it really means is "I'm empty, and I'm not used to that". We can go a lot longer without food that our stomachs would have us believe. | 2 |
7zi7d5 | Biology | Why is herpes on your lip (cold sore) temporary while genital herpes is for life? | Both forms of the disease have recurring temporary flare ups (visable sores) that appear then fade periodically and will continue for life. | 5 |
5uhr0x | Culture | Why is it appropriate for PG13 movies/shows to display extreme violence (such as mass murder, shootouts), but not appropriate to display any form of sexual affection (nudity, sex etc.)? | There are several reasons. First of all many people are uncomfortable talking about sex openly with children. Violence is something that they can wash away as "fiction" but sex is "real" and so they have to actually talk about it. Further, exposure to lots of violent imagery causes Mean World Syndrome in the population. This makes everyone fear each other and feel that the world is more dangerous than it actually is. This has the side effect of keeping people isolated instead of organized, they are then more likely to want authoritarian governments and it keeps them behaving as good consumers. URL_0 Finally, not all countries are this insane. In many European countries it's the opposite. Violence is taboo and sex and nudity is normal. | 51 |
9eod0c | Other | don't want to make an unrespectful question, but where does "simple" sadness ends and depression begins? | Depression isnt sadness, it's emotional numbness. Unless you mean the difference between short term and long term depression, where short term depression happens due to, maybe, a family member dying suddenly and long term is a disorder. In which case, long term depression happens for over 6 months and short term depression i believe is 2 weeks. Depression is described as a lack of interests in the things you used to enjoy, a comstant (or near constant) emotional numbness, and the lack of motivation to do simple tasks like cleaning, washing, reading, etc. I constantly find myself asking "what's the point" when playing video games. It doesnt help me, i get frustrated even though i used to love minecraft, amd no one will see or care what ive done anyway. Source: i have been diagnosed with severe clinical depression and anxiety for 13 years. | 4 |
ddktai | Economics | Generation Z appears to be, on average, so much poorer than those of their parents. For most, ever owning a house seems unlikely, and even car ownership is much less common. What exactly happened to cause this? | All the money went up. I guess some companies are making billions in profit and their staff aren't getting pay increases. | 48 |
6aeija | Technology | What is 'AI' in video games? My brother is big on game design and has recently begun going to university to study it - can someone give me an explanation of what constitutes an 'AI' in a video game, or how that works? It was my understanding that AI hadn't been invented yet, or is this something different? I hear it referred to as 'Enemy AI' a lot. I don't know a lot about this stuff but I'd really like to be able to keep up with my brother and still have detailed conversations with him, so I'm looking for an explanation that starts broad and gets more specific. Thank you in advance. | Ai is, like mentioned, artificial intelligence. it's simply the practice of getting a computer to react to its environment and act somewhat intelligently, to pretend it is a real, intelligent agent. So, computer players playing against the humans are AI, anything that governs an NPC's behavior is AI, anything that makes the computer react to the world it is living in is AI. Outside of video games AI has many applications, such as machine learning, data mining, factory assembly, pattern recognition, Targeting ads towards you, building cute robots, and so on and so forth. What you are referring to when you mention " AI hadn't been invented yet" is *true, general AI*. It's essentially when a single AI can learn, can think, can act, in essence is truly intelligent instead of just pretending to be. This is something that we have not achieved, or at least not fully. We're always doing research on AI and we've gotten some pretty smart robots, but we're a few decades off the singularity. | 3 |
inl990 | Engineering | how an air conditioner makes cold air. | When you compress a gas, it’s temperature goes up. When you decompress it, it’s temperate goes down. Air conditioners compress the gas and dump the heat outside of the building, then let the gas decompress in pipes in the aircon box. Then a fan in the box blows the cold air into the room. | 3 |
5w8a3l | Biology | Where does the web material go when a spider climbs back up? I was watching a small house spider today drop down from the ceiling on a strand of web. I touched it and it climbed back up the web. There wasn't a loop of web dangling below it. Do they just reel it back up inside like a yo-yo? Eat it? Where does the web go? | Spider dork here. Others here have mentioned they recycle the web by eating it, but not the method by which they climb up a strand without leaving any behind. They essentially climb with their forelegs and bundle it upwith their hind legs whilst holding the bundle with their fangs as they go and then hold onto it until they can eat it later. | 4 |
gr40q9 | Engineering | How do fiber optics transmit data using light? I understand how light physically gets from one place to another, but how does the other end know what data is being sent? | Imagine we're in opposite ends of a dark tunnel. We both have a flashlight. Before we went in though we agreed that we would follow the standard morse code to communicate. So if I want to send SOS (the only thing I know) I blink 3 times fast, 3 slow, 3 fast. Since we agreed beforehand I know how to send you a message and you know how to interpret it. It's the exact same thing in networking. | 4 |
duxbow | Technology | Why is salt mined when there's a bunch of it available in the ocean? I'm sure its harder than mining, but how and why? | Water loves salt. Getting water to give up salt is hard, so if you can find a place where past sunlight drove the water off to leave salt that saves process energy. | 4 |
neoui7 | Technology | The ads I see in fremium gaming that claim you can "earn real money just by playing!" aren't these just scams or are they real? I play this interior design game on my phone and I constantly get ads for other games that claim you can "win real money just by playing!" or "win real amazon giftcards by playing games!". I always just assume these are scams, but I'm curious: does anyone have any experiences with these "realmoney" games? Are they real or is it just another way for hackers to steal your info? | bit of both. this is generally these companies having deals with ad companies ot get your data/clicks in hopes you'll buy into them. honestly wouldn't recommend as this generally is how you end up with a crapload of spam mail and potentially leaked info. | 4 |
9r8q3a | Technology | what is the design process of building an application? | The design process or the development process? Development environments and technology standards allow for very agile, iterative approaches these days. So depending on the scale of the project (ie number of people) design phase might be skipped completely in favour of jumping straight into a working prototype. I'm a software developer and often the design phase is as simple as a few bullet points of requirements, maybe a sketch of the layout. We aim to get something working and usable as soon as possible, so we can get a smaller feedback loop. You don't want to spend 3 months working on something, then reveal it, only to have it be all wrong or unfit for practical use. & #x200B; A common approach in the industry is to have a collection of "user stories". These are simple requirements from the perspective of one or more user, which can later be translated into functionality and design choices for the developer. These user stories are then turned into work items and assigned to the appropriate developer. & #x200B; Example: As a customer I want to save my bank details for use later. As a customer I want to save my address for use later. As a customer I want to order pizza. As a driver I want gps navigation to the customer's house. As a vendor I want to upload my menu. | 4 |
78n2up | Biology | - Why is it that we can hold our bladders for hours, but as we get closer to a toilet it becomes uncontrollable? | I am not a scientest but I'm pretty sure it has to do with being trained that that is where we pee. Subconsciously you know that you can't per in the car so it's easier to hold putting a proverbial clothespin on your bladder, but once you know that you are within spitting distance of the toilet it takes that clothespin off. | 5 |
luwsan | Biology | Still and carbonated water taste To me, still water is bland but fine, even nice if chilled. Carbonated water, on the other hand, tastes like shit no matter its temperature. Even if it's gone flat, it still tastes awful. I dislike carbonated water to the point that even when I'm really thirsty and can down half a litre without blinking, I still will not drink carbonated water. Add flavour however, and still flavoured water tastes like shit (whether formally carbonated and gone flat, or never carbonated, it all has that 'flat' taste to me). Flavoured carbonated water is delicious though! Whether it's something heavily flavoured like coke, or just a lightly fruit flavoured sparkling spring water. Is there a reason for the difference? I am a supertaster and a dislike of carbonated water is common, but why the drastic change when a little flavour is added? | As explained by WIRED: "The carbon dioxide in your favorite soda pop tastes sour to your tongue, thanks to an enzyme that converts CO2 into protons that sour-sensing cells can detect. That means your Coca Cola isn’t just packed with high-fructose sweetness, but, perhaps counterintuitively, its carbonation delivers a delicious squirt of sour too, according to a new study." The acidity may be unnerving to taste in something like water, which we know to be neutral-tasting, whereas with a mild fruity flavor, that "tangy" aftertaste is likely more familiar. | 1 |
mggjnw | Biology | Why does being sedentary degrade our bodies and deteriorate our health faster than being physically active would if exercising is more directly stressful on our bodies? Now that I think about it, it's seems counterintuitive that causing your body to work more will preserve it better than being less physically in the long run (assuming that you have the same body mass and composition in each case). Why is that? | In essence, it's because your body is lazy, and it's evolved to be. In the environment we evolved under, being sedentary for long periods of time was simply not something that was possible (you'd run out of food and die) - so which muscles and other tissues you regularily used was a pretty good measure for which ones you needed. As a result, muscles you aren't using or are using less essentially gets maintained less well to save energy, because your body doesn't think you need them. Evolutionarily speaking, being efficient and saving energy is far more important than maintaining less-frequently used tissues. On a more mechanical level, a lot of the mechanisms that repair and maintain your body rely on signals that are produced by exercise to get started. (This is also why physical therapy is important for healing many injuries - without the stresses of appropriate exercise a lot of repair mechanisms simply don't start.) A lot of cells in your body can sense mechanical stress and respond to it, and quite a few growth and repair pathways are the result of such responses. | 4 |
kqgrxl | Other | What exactly was the Watergate scandal and how did it cause Nixon to resign? | The story was unfolded when a brake in attempt at the Democratic campaign offices was thwarted by a security guard. The criminals had attempted to steal secret document from the offices. The evidence quickly lead the police to senior members of the Nixon reelection campaign and it was quickly suspected that Nixon himself was involved. And the more the police were looking into Nixons senior staff the more evidence of illegal activities were uncovered. Including illegal wiretapping, corruption, kidnapping and obstruction of justice. One of the most damning piece of evidence was an illegal wiretapping made by Nixon himself in the oval office discussing the brake in at Watergate making it clear he was personally involved. Congress got sworn testimonies from people who had heard the tape and ordered the white house to release it. They answered that the tape had been destroyed and no copies were available. However the tape was eventually released. A number of Republicans were sentenced with criminal charges. However Nixon resigned and were then immediately pardoned by the vice president and therefore evaded justice. | 5 |
7m630p | Repost | Why do plastic water bottles start to smell bad when left for a prolonged period after being opened? | Ahoy, matey! Yer not alone in askin', and kind strangers have explained: 1. [ELI5:Why does water left in bottles start to smell bad after a few days? ]( URL_0 ) ^(_19 comments_) 1. [Why does a plastic bottle start to stink after a while? ]( URL_3 ) ^(_5 comments_) 1. [ELI5: Why do many plastic water bottles cause the water to smell/taste bad after being opened and allowed to sit for a while? ]( URL_1 ) ^(_2 comments_) 1. [ELI5: Why do plastic bottles stink after a couple of days with the same water? ]( URL_2 ) ^(_3 comments_) 1. [Why does my water bottle keep smelling bad? ]( URL_4 ) ^(_9 comments_) | 2 |
dh4sxx | Technology | How are sports broadcasters able to pull accurate and very oddly specific stats instantly about what has happened on screen? | High quality broadcast teams have skilled spotters and research teams that feed them stats through the game. Poor ones, like the ones in Canadian Football, will have pregame research done on a player and regardless of what happens, only ever talk about that one player they researched. Even if the game doesn’t dictate they put the focus on that player. | 3 |
ijr71a | Other | Why is it so hard to adapt to another sleeping position? And how do we develop a main sleeping position in the first place? | Your muscles adapt to a common length based on what you do most often(if you're not stretching and exercising). These contractures and adhesions lead to an optimally comfortable position. Usually it will mimic the life of the person. Desk workers will usually side sleep in the fetal position (closest to sitting in a chair) laborors may sleep on their back with their arms behind their head. Also, a partner and animals, as well as injuries, can alter the sleep position further. Edit: to change, you can get a massage and chiropractic adjustment to realign the body, then sleeping with pillows to hold you in a different position comfortably can slowly change your preferred sleep position. | 2 |
ez4h7p | Physics | why jumping on top of a moving train is not like jumping inside it? Imagine you’re on top of a moving train, if you jump, you won’t land at the same spot before the jump, but you’ll land behind where you jumped and you may even fall. But when you’re inside you’ll land in the same spot. I don’t understand that. | Jumping inside or on top of a train should be the same. This question is a false premise. The only difference you may experience is wind resistance, which may push you back a bit. Otherwise, from the frame of reference of the train, you're standing still either way. You're still matching the trains velocity. | 3 |
m2lt4x | Physics | If the exoplanet HD 100-546 is larger than some stars, how come it hasn’t collapsed into a low-mass star? | HD 100-548 is far from being large enough in terms of mass to turn into a star. It is not even big enough to be counted as a 'Brown Dwarf' which are basically larger versions of HD 100-546b. HD 100-546b maybe larger in terms of volume than say a red dwarf (which is a star) but it has no way close to enough mass to turn the fusion on. | 5 |
97m1es | Physics | What’s the difference between centripetal force and Centrifugal force I know it has something to do with spinning things but I never understood the difference. | "Centripetal" is a description of the *direction* of a force, meaning "toward the center" (of a circle). It's used in the same sense as "upward" or "to the left". There are lots of things that could cause a centripetal force, just like there are lots of things that could cause an upward force: string tension, gravity, friction, etc. "Centrifugal force" describes the fact that because objects have inertia, they tend to continue in a straight line rather than go in a circle. It *seems* like there's an invisible force pushing them away from a circular path, but really it's just that they want to keep going straight. To make things go in a circle instead of a straight line, you need a centripetal force of some kind to push them sideways. | 2 |
a4ls7t | Mathematics | What is Scalar (mathematics)? | Basically, it's just a number. It is in distinction to something like a vector, which is a quantity that has both magnitude and direction. A scalar has magnitude, but no direction. For example in physics, velocity is a vector quantity, but speed is a scalar quantity. | 2 |
kowyxc | Technology | How can a 4K video look clearer on a 1080p display even though there aren't as many pixels on the 1080p display to show more detail in the 4K video? | Well, if we're talking streaming video here, when they encode the video for 1080p they'll compress it far more than they do the 4K one, simply because they can--people aren't going to notice loss of detail due to compression artifacts as easily on 1080p as they are 4K. So, the 4K video will have fewer such artifacts and will generally be higher quality. Same applies on Youtube or the like--viewing a 1080p video on a 720p display will generally look better than viewing the same video at 720p on the same display. | 12 |
benbh0 | Chemistry | Why does onion turn translucent when it's cooked? | The water in the onion's cells boils and breaks the cell walls. The cell structure breakdown reduces its opacity & rigidity. They then turn brown as the sugar in the cells caramelizes and becomes super tasty. | 6 |
lspy7y | Chemistry | What happens to all the melted candle over time? Are we just inhaling a whole candle while it burns? | Yes, kind of. Also, burning a lot of candles inside your home isn't too good. We once had a neighbor who really liked candles. Once I was looking after her pets when she was on holiday and I noticed a thin layer of black material on the windows and ceiling. I then browsed a bit and there are candles that aren't that bad for you. | 15 |