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6mqbwz | Physics | how does having two eyes increase our depth perception? My depth perception seems the same whether I'm looking out of one eye or two. | So, having two eyes allows you to [triangulate]( URL_0 ) distance. Knowing the distance between your eyes and the angle to the object you're looking at from each eye, simple trigonometry allows you to calculate the distance. Your subconscious does this automatically. Your brain also uses other cues to judge distance: how big the object appears, compared to your memory of how big objects like that actually are; whether other objects are in front or behind it, and where that places it in the scene in front of you; whether the object appears faded or fuzzy because there's a lot of atmosphere between you and it, etc. Now, the reason you don't notice a difference when you close an eye is because your brain has already constructed a model of the environment around you, including how far away things are. It doesn't forget the triangulation it made just because your eye closed -- the calculation has already been done, and your brain has no problem filling in the blanks with the information it gained earlier. | 2 |
kytl8u | Other | Why are there different variants of sign language? Couldn't one form become universal and be understood by all people regardless of language? | I was told of this but in Australia the deaf use Auslan. And a woman went into the local school for the deaf and asked if they had an American exchange teacher working with them. They said yes why. Apparently a bus load of small children past her signing out the song Twinkle twinkle little vagina. LOL. Apparently the sign for vagina in Australia is the same as star in America. | 8 |
696bf7 | Other | Why is it preferable to have illegally obtained evidence thrown out of court as opposed to keeping it and prosecuting the one who obtained it? | If the evidence was obtained illegally, there's good cause to suspect that it's been tampered with otherwise, or processed incorrectly, or perhaps not even valid evidence to the crime in the first place. Another way to look at it is that if the officer was willing to break the law to get the evidence, who's to say they weren't willing to break the law and fake the evidence? This all follows from the idea that it's better to let a guilty person walk free than to put an innocent person in jail - and if you disagree with that, imagine if you're the innocent person. No, really, think it through, for a few hours. | 20 |
6bb21w | Physics | Where do I end, and where does my bed begin? If I'm laying here... at a molecular level is there a clean divide or a gradient area where I'm part mattress? | I get that things never "touch" due to electron clouds, molecular bonds and all that jazz, but is that gap measureable? Can we see it with a powerful enough microscope? Id love to see the gap between 2 metal plates, sorta touching, but not really. If you take two hunks of large nucleus atom, or a large molecule, and put them together, is there a big enough gap for a hydrogen atom to slip through? Can photons traverse this gap? Dammit, I have more questions than answers now. | 6 |
9fq77u | Technology | Why do submarines have to surface at all? Can't they just operate underwater for the entire length of the mission, especially if they are nuclear-powered? I have heard that diesel engines cannot remain submerged for a long time, so they have to surface very frequently. But what is it they actually do by surfacing? Also, I understand that nuclear submarines can stay underwater for a long time, but even they do surface once in a while. My question is - why? Why do they have to do that? Can't they remain submerged during the entire mission? | Former Submariner here, and theoretically, without getting into too many details, they can. Technically the only thing that would keep them from staying at sea, submerged indefinitely is the amount of food they can carry to feed the crew. | 24 |
5oumxi | Other | The French Foreign Legion and the Siege of Jadotville I just recently finished watching The Siege of Jadotville. I found the context interesting and wanted to do research on the actual events and story. I came cross a man named Roger (René) Faulques whom fought AGAINST the UN and Irish soldiers as a mercenary. Now I learnt France honoured him for his actions while at the same time he attempted to kill UN soldiers. How could the french allow for this and does this happen still? The Siege of Jadotville happened in 1965. | So, let me begin by dispelling the common notion that UN resolutions carry some sort of weight of law. They do not. There is no law in international politics. Countries can and frequently do ignore UN resolutions when they feel those resolutions are in the slightest bit inconvenient. Rather than viewing a UN resolution as law, its more accurate to view it as a sort of general proclamation of how the international community feels on a subject. UN Security Council resolutions are no different, but they are backed by the fact that the five permanent members (the US, Russia/Soviet Union, China, UK, and France) have to all agree to them. But that does not mean that those five members always *actually agree* with every security council resolution. Sometimes they don't agree with those resolutions but allow them to go through because they have been paid to do so, or blocking a resolution would look bad. France's vote on the Security Council resolution that authorized UN forces in the Belgian Congo was one of those instances. When you hear about the Cold War you frequently hear about it being a conflict between the US and Soviet Union, but that isn't correct. The Cold War was actually three different conflicts, of which the US-Soviet was the most prominent. But there were two others - the Soviet-Chinese conflict which is irrelevant here, and the France-Everyone Else conflict which is. Throughout the Cold War France continually sold itself to countries in the third world as a viable partner in opposition to either the US or Soviet Union. They weren't particularly successful in this, but did manage to form a loose coalition in which Iraq, Libya, and some West African countries were "allied" with France against both the US and Soviet Union. One of those "countries" was Katanga, which was a breakaway state from the Belgian Congo. The Belgian Congo was a Belgian colony until 1960 and France felt that this status made it a part of the French sphere of influence. But when it gained independence the Belgian Congo completely severed its ties with Europe and eventually came under the control of Mobuto Sese Seko, who was a strong US ally and virulent anti-European. The UN Peacekeeping force came about as a result of some weird Cold War politicking in which the country descended into civil war immediately upon gaining independence and the Soviet Union, which thought that a post-independence government would support it, threatened to send troops to the country unless a UN Peacekeeping force was sent to stabilize the country. The French didn't want the peacekeepers there because they wanted to support to rebels and overthrow the new government. But at the same time they couldn't veto the resolution because doing so would have caused the Soviet's to intervene. But as I said, the French did not want the UN Peacekeepers there - they wanted to get rid of the anti-European, pro US post independence government and replace it with a pro France government. In furtherance of that position the French began to clandestinely support the Katanga rebellion. As part of their support, they authorized members of their military to go on "leave" in order to become paid mercenaries for the rebellion. Roger Faulques was one of those French military servicemen. The French honored him for his actions in that battle because he had either been ordered to be there, or had gone there as part of a volunteer force in support of official French policy. | 1 |
62st77 | Engineering | Why can't magnets create perpetual motion? | The first two laws of thermodynamics; 1) Energy cannot be created or destroyed in an isolated system. 2) Entropy of any isolated system always increases. Magnets can not add energy to the movement for they have no energy of there own that is coming in. They are a constant force. In this system the friction of the pendulum will stop it and it will hit a point of equilibrium. | 9 |
9ffe02 | Physics | Why do hurricanes hit the U.S. East Coast so often but never on the West Coast? | Hurricanes do hit the western US, its just happens significantly less. At least once every 2 or 3 years the remnants of a hurricane will pass through Arizona. | 17 |
b8lvyr | Engineering | How does a helicopter pilot bail out if he is going down? Clearly they can’t use an ejector | Helicopters can autorotate, which means they use the big propeller on top to slow themselves down and land somewhat safely. To do that, they switch the way the blades are facing so the air going by as they fall makes the blade rotate, then switch them back to make them lift the helicopter. Some military helicopters, though, do actually have an ejection seat. The same control that fires the ejector also fires explosive bolts that release the rotors, so they fly off before the pilot can hit them. (I learned that from an Apache pilot at an air show.) They try really hard not to use that system, but if they're too badly damaged to autorotate, it's better than just hitting the ground. | 8 |
768uzt | Biology | how can you get a bruise or a cut and not notice or feel it until you either use hand sanitizer or someone notices and tells you | Your skin has specific types of nerve cells to signal different sensations to your nervous system. For instance, when you put pressure onto your skin, that activates pressure sensitive nerves, which send the signal to your brain, and you feel pressure there. Likewise, there are specific nerve cells that signal pain, called nociceptors. Nociceptors fire in response to a few different stimuli, including high temperatures and tissues being damaged. There are several different kinds of nociceptors as well, that respond to different stimuli (although there may be some overlap). If you're very lucky when you get cut or bruised, you may not activate the nearby nociceptors, particularly if it's not a particularly large injury. The nociceptors have an activation threshold - just like something may not be hot enough to be painful, your injury may not be bad enough to activate those nerves. Or if it's a small cut, it may just have managed to miss the nerves entirely. Once you're cut, though, your body will still activate some parts of your immune response, including those that make nearby nociceptors more sensitive. There are some nociceptors that don't even activate at all until there's already been an immune response. And because there are different kinds of nociceptors, when you use hand sanitizer, you're activating the nerves that are sensitive to harmful chemicals, even if the ones sensitive to tissue damage still haven't activated. Or if you poke a bruise, you may activate some of the pressure sensitive nociceptors that hadn't fired before. There are also a number of reasons why your nociceptors might fire, but you won't notice. Your brain does a lot of prioritizing of what signals to make you consciously aware of and deal with. If an injury is small enough, if you're busy doing other things and worrying about other things, your brain may ignore that signal. The nociceptors can't fire forever, so eventually they'll stop and it won't be until after then that you have the brain space to pay attention to the pain. Imagine, for instance, someone who is busy playing an intense sport and they get a small cut: they're too busy trying to win to notice. You can also train yourself to ignore pain and get used to it, so that eventually you just fail to notice it consciously. When you are made aware of it, when someone points it out, suddenly your brain is focusing on those signals and letting them through to your conscious awareness so it starts hurting. And again, if you poke the injury or try to wash it, you'll be activating additional nerves. The small signal coming from the cut before may not have been enough to cross the threshold of pain in your brain, but suddenly a bunch more are firing, making the signal stronger so it's enough to get through that priority filter so you consciously feel it. | 1 |
geia33 | Economics | Keynesian economic theory Could someone explain it to me? I tried reading about it from various sources, but I'm not sure if I completely understand it. I need to be able to explain the theory in high school. Thanks in advance! | For high school level-economics, calculating a country's gross domestic product is usually done with this simple formula: GDP = C + I + G + (X – M) GDP = private consumption + gross investment + government investment + government spending + (exports – imports). In periods of economic downturn, private consumption and gross investment will decrease as individuals and businesses are less likely to have the money to spend. Keynesian economics says that increased government spending can offset that decrease. | 4 |
l7ckr5 | Economics | Stock Market Megathread There's a lot going on in the stock market this week and both ELI5 and Reddit in general are inundated with questions about it. This is an opportunity to ask for explanations for concepts related to the stock market. All other questions related to the stock market will be removed and users directed here. How does buying and selling stocks work? What is short selling? What is a short squeeze? What is stock manipulation? [What is a hedge fund?]( URL_0 ) What other questions about the stock market do you have? In this thread, top-level comments (direct replies to this topic) are allowed to be questions related to these topics as well as explanations. Remember to follow all other rules, and discussions unrelated to these topics will be removed. **Please refrain as much as possible from speculating on recent and current events.** By all means, talk about what has happened, but this is not the place to talk about what will happen next, speculate about whether stocks will rise or fall, whether someone broke any particular law, and what the legal ramifications will be. Explanations should be restricted to an objective look at the mechanics behind the stock market. EDIT: It should go without saying (but we'll say it anyway) that any trading you do in stocks is at your own risk. **ELI5 is not the appropriate place to ask for or provide advice on stock buy, selling, or trading.** | Ok, so they burrow the stock and sell it. But from whom do they borrow and where do they pay interest? | 489 |
o0evad | Economics | Why have most prices been continuously increasing for several decades but wages haven’t been at the same rate? | Rich people used their money to bribe politicians into changing the rules so they could keep and make more money. Then they did it again. And again. Then they used that money to buy all the major media everythings and used THAT power to convince all the poor and middle class people to fight each other for the scraps left over instead of realizing the problem was those rich people. | 5 |
87s46l | Technology | How does CGI “age?” If something looked real “at the time” why does it look less real now? | Something other people haven't addressed is increased resolution; CGI made for a standard definition release looks garbage on a HD monitor, it's the same for HD to 4K too. | 29 |
6f40be | Mathematics | Why does e (the number) come up in so many seemingly random applications? | It comes up a lot because it is a function whose derivative is proportional to its current value. Many differential equations that describe natural phenomena show this kind of dependence, making (e) inevitably show up in the solutions describing these natural phenomena. Another way to think of it is in terms of the Euler equation and Eigenfunctions. Many system models describe systems as Linear Time Invariant (LTI) systems. In these systems, the exponential functions with a complex argument is an Eigenfunction, i.e. a complex e stimulus yields a complex e response with some scaling factor. This makes them the simplest, concise and complete way to describe the response of such systems. I know this is too much technical jargon. I can try to simplify it further if you want. Edit: a better answer is down below in the comments | 5 |
6wlo6e | Biology | Why do we feel the compulsion to do something physical (punch/scream/kick) when we get angry? | When you get angry you get stressed. When you get stressed your body reacts by releasing chemicals like adrenaline. It's like a fight or flight response, if fear is flight then anger is fight. All of the energy produced by these things has to go somewhere and you get the urge to do SOMETHING and due to the stimuli that caused the reaction it's usually something violent or aggressive. From [this article]( URL_0 ) > "Emotions more or less begin inside two almond-shaped structures in our brains which are called the amygdala. The amygdala is the part of the brain responsible for identifying threats to our well-being, and for sending out an alarm when threats are identified that results in us taking steps to protect ourselves. The amygdala is so efficient at warning us about threats, that it gets us reacting before the cortex (the part of the brain responsible for thought and judgment) is able to check on the reasonableness of our reaction. In other words, our brains are wired in such a way as to influence us to act before we can properly consider the consequences of our actions." Basically, you begin to react to whatever made you angry before your brain judgement kicks in. This can cause people to do some of the irrational things they do when they get angry (punch a wall, scream, pull their hair out, etc.). | 1 |
did0zd | Mathematics | What makes "Median" a relevant metric? | Usually it's when you are concerned with distributions. In the case of median income, you'd rank everyone's income, and pick the person exactly halfway down the list from biggest to smallest incomes. Same with houses, if you made a list of houses from most expensive to least expensive, it would be the one halfway down the list. Let's say you have 2 different 10 person companies, and in one, everyone makes $100K a year. In the other one, the boss makes $910,000 and everyone else makes $10K a year. In both cases, the average or mean income is $100K a year, but in the first one, the median income (what the Fifth and 6th highest paid people in a 10 person company makes) is $100K a year, and the second one the median income is $10K a year. If there is a big difference between the mean average, and the median it usually means there are a few outliers at the very top or very bottom that are high or low enough compared to the average that it skews the averages. | 4 |
8ubaen | Technology | Why does having WiFi turned on improve location accuracy on iPhones? | WiFi access points help to triangulate the position of a device whose WiFi is turned on. Thus, all a phone needs to do is detect various WiFi hotspots in its range, and then its location accuracy improves, because the geographical location of millions of WiFi access points can be obtained from a centralized database | 3 |
8psefh | Biology | If your muscles produce water as a waste product from burning glucose, why do you also need to drink water? | You lose water through other routes, whether its through sweating, or breathing out (condensation through your breath) or pee. The amount that your body generates through using glucose isn't enough to sustain you. Generally, you need to pee a certain amount out every day to get rid of the bad stuff that's in your body. Technically you don't actually need to drink water. A lot of water comes from your food, and if you eat a lot of water-rich food, you can survive without drinking fluids per se. | 1 |
bv01bd | Biology | What happens to the body/brain when people faint at the sight of blood? | You get spooked and your arteries and veins dilate. Your heart can't keep the blood pressure up, so the blood pools in your legs and your blood pressure drops. So the blood can't get to your brain. This causes you to faint. It's called a [vasovagal response]( URL_0 ). And that's why sitting down and squatting will prevent you from fainting, since it makes it easier for the blood to get to your brain. | 1 |
hny7vp | Other | - How does someone like Dominic Cummings achieve the level of influence his position in government affords him? | Dominic Cummings' political reputation comes from two main sources: campaigning and being a special advisor. His most prominent campaigning role was with the Vote Leave campaign. Obviously this campaign was successful, which is a strong point in his favour. The campaign also used quite distinctive tactics, such as a lot of data mining and online advertising, and a particular disregard for things like established institutions, norms and the truth. This would put some people off him, but not our Prime Minister, who has a history of lying. Cummings also served as special advisor (spad) to Michael Gove from 2007-14 - a fairly long stint in that kind of role. Spads are there to support ministers with political decisions. Unlike the Civil Service they are appointed by ministers and are not politically neutral. While they might have been political rivals, Gove and Johnson are not so far off ideologically. So the influence of Cummings or someone like him (I'm not sure there *are* any comparable figures, though the level of his influence is much debated) comes from a range of things. Most of all it comes from having the ear of the Prime Minister, a very personal relationship that relies on the PM being ideologically in tune with him and trusting his judgement. You might also wonder if Cummings is willing to make hard decisions and dig into detail that Johnson finds difficult - the latter being famously pro cake and pro eating it. | 1 |
bldp09 | Biology | what are prion diseases? Are they like other diseases or are they completely different? | Bacterial diseases are caused by bacteria, viral diseases are caused by viruses and prion diseases are caused by prions. Prions are proteins that can have two states (or more) one that is harmless, and one that is harmful. And unfortunately a prion in the harmful state, can cause other prions in the harmless state to switch into the harmful one. So once you have a couple of harmful prions, they turn the other ones which turn other ones and they become more and more, zombie apocalypse style. & #x200B; And also zombie style, the spongioform encephalopathy prions (mad cow disease, creuzfeldt-jakob disease, scrapie, etc.) eat holes into your brain. | 2 |
jp2x3k | Physics | What would you hear if you were travelling at the speed of sound towards/away from something making noise? What would you hear if you spoke? | If you're inside a cockpit you will hear yourself speak normally because the air in the cockpit travels with you. If you're not in a cockpit, well you won't hear anything beside the roaring of air ripping your skin off, but if you don't take that into account you'll still hear your voice because the sound propagates through your skull. | 3 |
nb3pjz | Engineering | Even if pipeline computers are hacked, can’t the valves be opened and closed manually to keep fuel flowing? | The pipeline operational controls weren't hacked, it was all of the ancillary systems. Customer management, orders, logistics, etc. The pipeline was shut down because they couldn't track who was buying what from where and for what price. | 2 |
euz060 | Other | Are there notes in-between the half steps of a piano? I'm sure this has been asked before, but I couldn't find anything online. Are there notes in-between the piano keys? And if so, why are they never used? Do they sound terrible? I'd love it if someone could clear it up. Thanks! | Charles Ives made quarter note pianos with the "notes" in between the usual keys. It's pretty interesting stuff! URL_0 The video features a video of said piano | 6 |
6lmy1l | Economics | Could someone explain me why such thing as toll roads exist ? | [here's a video]( URL_0 ) of a toll road made by a private citizen to go around a damaged section of road. Before the toll road, the detour was 14miles. In the video the guy explains he had the road built by a construction company on credit - his house is the security in case the toll charges don't cover the costs. Extrapolate this situation up to a larger scale: Private companies spend large amounts of money to build roads/bridges/tunnels and charge a toll to make their money back and turn an investment. | 4 |
fw6i0g | Chemistry | How does rocket fuel ignite and burn in space in the absence of oxygen? | An ordinary fireworks rocket would work just fine in space, its black powder propellant has its own oxidizer built in. | 4 |
ggpjtl | Chemistry | What is the convention for naming new drugs? I mean they have all these weird unpronounceable names so they have to give them different names. What is the story on that? | The brand name is whatever the marketing department of the company comes up with. The generic names have some general guidelines to follow (like certain types of antiviral drugs ending in -vir, monoclonal antibodies end in -mab). Generally, the rest of the generic name is some sort of reference to a certain part of the structure of the drug or a certain enzyme that the drug targets. | 1 |
8mdw4u | Culture | Amish are famous for barn-raising, but how often do they actually need to raise one? | Not often, it's just an interesting sight to see a hundred men build a barn in a day instead of the usual three men taking thirty days. Since they're not paying for the labor, they can pull of the brute force build that a typical construction firm cant. | 3 |
8ti2ej | Engineering | Why do wine bottles have that huge indent at the bottom? | They're called 'punts' and are tradition at this point. Back in the era of glassblowing every bottle by hand, punts were the last section of the bottle to be formed. | 2 |
nyg31l | Chemistry | How can edible things have zero calories? For example: mustard. | There is also the fact that if it is less than 5/calories per serving, they are allowed to round down to zero. This is why some packages that have both per serving and per container facts on it may say 0 calories per serving but 15 calories per box. | 5 |
dwlfa5 | Biology | If identical twins share the same DNA, why do their fingerprints differ? | Genes are more like a recipe than a blueprint. Two muffins from the same batch will look different close up. | 3 |
gz5idy | Engineering | Why do ships have circular windows instead of square ones? | A circle has infinite points, a rectangle has 4. Less points = more stress. Hull warping and twisting = stress. Stress will find the easiest outlet to relieve itself. | 15 |
f8gy46 | Biology | How can Type 1 diabetes have any hereditary components if having it was a death sentence over 100 ago? Wouldn't all genetic traces of it had been destroyed prior to the 20th century? | Because people carrying it had complications or died from it AFTER they conceived children. | 5 |
n4wljd | Biology | How is an animal or human able to sense where on its body something is touching its skin? I know there are topographical 'maps'in their brains, but how does this translate to an individual knowing where on its body the touch is being applied? | The individual touch-sensitive nerves all over your skin are connected to that "map" in your brain. Your brain knows "when this nerve lights up, that's my left index finger" (or whatever) because it's got a continuous nerve connection all the way out to that physical location. Areas with high nerve density (fingertips, lips, genitals, etc.) have very good resolution...you can feel very fine changes in position. The use correspondingly more brain space to process. Areas with low nerve density, like your back, have lousy resolution because one nerve is covering a much larger area | 1 |
9ukkxp | Chemistry | Can someone really O.D. from potassium, and if so, how much would someone have to have to cause negative side effects? | The LD50 (the dose that'll kill 50% of people) for potassium is 2.5 grams per kilogram of body weight. For a 80kg person, that is 200 grams. A banana contains around 0.8 grams of potassium. If a 80kg person were to eat 250 bananas, they'd have a 50% chance of dying. However, the body naturally excretes potassium. Assuming you're well-hydrated and very healthy, your kidneys can filter out around 18mg of potassium per kg of body weight each hour. Our 80kg person would be reducing their potassium by 1.4g per hour, meaning that each hour you lose nearly 2 bananas worth of potassium. If you managed to eat 1 banana every five minutes (and keep it all down), then after an hour you'd only retain 10 bananas worth of potassium, not 12. So, if you were to constantly eat bananas for 25 hours, non-stop, you would stand a good chance of dying from potassium intake. | 1 |
dn1jgz | Biology | Why is it harder to swallow a pill or tablet than a piece of food the same size or bigger | Speech pathologist here (we treat dysphagia, or swallowing disorders, in addition to communication disorders). Taking pills is more difficult because the liquid we often take pills with moves much more quickly than the solid consistency of the pill. Therefore, we’ve already swallowed the liquid (or lubrication we’re using to take the pill) before it makes it through the pharynx. You can actually compensate for this by taking pills in something thicker, like pudding or applesauce. | 9 |
jjgfbo | Biology | What is a panic attack. Like what causes and what is happening during it | They're awful. You literally believe with every ounce of logic that you're actually dying. You literally couldn't be more afraid. It's your bodies "fight or fight" response turned up to 11. What triggers them varies. I get them from disappointing figures of authority in my life, like my employer or someone I really respect. Some people get them from talking to crowds, or just plain worrying too much. Sometimes there isn't even a clear reason as to why. But when it starts, it's extremely difficult to calm yourself down because your entire perspective changes. Like I said, you literally believe you're dying. It's hard to talk yourself out of that. | 5 |
g2274s | Biology | What do the “absolute threshold for touch” mean? I saw in another ELI5 comment thread that the absolute threshold for touch is a bee’s wing dropping onto a person’s cheek from one centimeter away. What does this mean and how did they determine it? Edit: does* | I believe that is the lightest sensation that can be perceived by our nervous system. How they figured it....I hope not through trial and....error. | 1 |
71wzo4 | Engineering | What is the science behind ICBMs? | The B stands for Ballistic, which means that the missile is boosted by rockets to a high altitude, then falls back down unpowered at an extremely high speed - something like 7 km (4.3 miles) per *second*. The sheer speed, combined with the lack of flames out the back, makes an ICBM extremely hard to track and intercept, by design. So the missile itself is fairly simple in principle, but getting it all to work is harder. If the missile's trajectory is set correctly during the boost phase, it means little or no correction is required during the terminal phase. Modern ICBMs have multiple independently-targeted re-entry vehicles - MIRVs -which separate from the missile and have their own rockets and guidance systems. The sheer speed of re-entry can't be over-stated. At 7 km/s, that means the warhead goes from 14 km up - 46,000 ft, higher than any commercial airliner - to the ground, in *two seconds*. | 1 |
b9fpau | Technology | How do images get printed on cakes or beer foam? | Same with home inkjet printer. Just that the ink that's used is edible ink. Tiny nozzles spray high pressurized ink onto a print media, in this case a cake or coffee foam | 1 |
a6acj0 | Culture | Why is KFC a christmas thing over in Japan? | KFC put a lot into marketing. Christmas in Japan is a fun, commercial holiday. Closer to valentine's in its seen more as an adult and romantic holiday then religious or for kids. The marketing worked, they offered much higher quality meals on top of the normal stuff, and so people liked it and it became a thing. | 6 |
9q5c3f | Technology | Why do some songs sound much louder/crisper than others on some music streaming services? | Before streaming services, music was mostly heard on the radio and on media like vinyl records, cassette tapes, and compact discs. Part of the process of producing music is a phase called "mastering" where the recorded songs are tweaked to sound the best on whatever format they are being sold in. So a version of a song could be mastered *differently* for a record, cassette, and CD. & #x200B; Now that we have digital music streaming, songs are being mastered for those services as well, but the different is that each service also tweaks the audio after it's been given to them. Each service does this differently. & #x200B; So there are lots of things at play here, some songs might be mastered by the record label differently for different streaming services, *and* each service does their own tweaks before it get to the users. | 1 |
7414mj | Biology | Voices usually sound tired early in the morning. What's the best way to "wake up" our voices quickly? | So I'm not sure there is a scientific way, but I'd say practice makes perfect, i tended to be late for things from time to time and get calls like "where are you, are you still in bed?" Kind of stuff. So before you answer the phone, Start off with a low growl and then raise it till you have kind of a shout. This should clear any flem and give your vocals a nice stretch. Secondly practice a "retail" voice, sharpness and clarity is key. And lazyness that's the driving factor behind it all!! | 2 |
7ddqq1 | Biology | why do scuba divers need to continually breath out when the take the regulator out of their moths but free divers do not When I was taking my diver training (I’m extremely new to this) my instructor told us that if for whatever reason you need to take the regulator out of your mouth you should exhale slowly. If this is actually necessary how do free divers not need to do the same? | Free divers have lungs full of surface air -- almost empty at depth as it compresses. Scuba divers have lungs full of compressed air -- several lungs' worth as it expands to surface pressure. | 3 |
j0zo39 | Chemistry | Why does MSG have such a bad reputation? | Alternative bonus answer: because the Knicks haven't been good for a while and the owner is a bad man. Edit: I used "bad man" because every other descriptor I thought of was not appropriate for a 5 year old. | 11 |
8w1ti8 | Technology | what is MIDI and how is it used? | [Wikipedia article]( URL_0 ). It's a set of standards (computer software, cables / connectors, etc.) for connecting musical instruments to a computer, in order to record or create music. You always have the option of using a microphone next to an acoustic instrument to record it, but this would result in recording the "sound" (.wav file) rather than the "notes." The MIDI interface records the notes; you can connect a MIDI keyboard or MIDI guitar and play the notes you want, and the computer can then change the "sound" of the notes from violin to piano to drums to synth / electronic, whatever you want. This lets you use a keyboard (for example) to first record the drum beats, then record the bass guitar over the drum beats, then add piano, violin, guitar, whatever; basically you can create a full symphony or full song with just a keyboard - you don't need all the instruments that an orchestra needs. | 2 |
6bl3op | Culture | What prevents someone from creating their own religion that practices drug use, and then doing those drugs in accordance with the First Amendment (Freedom of Religion)? | You would need to be prepared in court to prove that your religion was sincere and viable. It would be a hard and expensive fight. You would then still be liable for any drug use, or distribution, that could not be proven to be soley for ritual purposes Still, drugs would be easier to pass than say, a religion of robbery. Some drugs are already permitted for some adherents to some religions. | 2 |
6c6xlt | Culture | What do pharmacists do besides count out pills and put them in a bottle? There's obviously way more to the job | I'm not a pharmacist, but I have worked as a pharmacy technician. Pharmacists communicate with doctors and patients to resolve issues with dosage and interactions. Techs and clerks in pharmacies are the ones who count and fill the prescriptions. | 6 |
61ybnr | Biology | Why is the skin on our arms and legs generally clear and beautiful, while our faces and back tend to get acne and clogged pores? | Most people are kind of stating the obvious I think: your face has more/larger pores. Most of us can tell that just from looking at our arms and face. What I don't understand is why does our face have bigger pores? Is it because we need to sweat more there to keep our brain cool or something? Maybe because the sun hits our face more often, so it gets hotter? | 13 |
il4pt7 | Physics | Small dimensions? I once heard this quote on a YouTube video: "String theory suggests there's actually 11 spatial dimensions, but only 3 are big enough to notice" How can a dimension be big/small? AFAIK whenever we measure stuff (like distance/volume) it's always with respect to a (set of) dimension(s)...so this seems completely backwards to me. Here's the video in question: URL_0 | The space doesn't have to be "flat" in a given dimension. It's actually a [major cosmological problem]( URL_0 ) whether our "normal" 3 dimensions are flat. It's theoretically possible for a dimension of space to be looped on itself, so if you travel far enough in a given direction, you'd end up where you started (like walking across a sphere). In this case the dimension is infinite. So it's suggested that these additional dimensions are looped but have a subatomic size so it only has any effect on quantum scale. | 2 |
cjovim | Economics | Why some factories runs 24/7 while others can do only dayshifts? | The cost of running a factory can be split into both fixed costs and unit costs. The fixed costs are costs of the equipment, tools, buildings and such which does not depend on how many actual units you produce. The ratio between fixed costs and unit costs varies a lot between different products. If you have more shifts you increase the unit costs as people want more pay to work nightshift and weekends but the fixed costs stay the same with more units produced. So if you have high fixed costs it may be benefitial to run the factory 24/7 whereas if you have high unit costs you may only run the day shift. Factories might also add or remove shifts depending on the demand so a factory that might only be designed to ten shifts a week might during high demand run twenty shifts without having to buy new equipment or build new buildings. | 2 |
gdqbrl | Technology | Why is it not recommended to have 2 antivirus programs running at the same time? | The same reason you don't have 2 chauffeurs. They fight over the wheel and eventually your car is gonna hit something. | 6 |
a4ftky | Mathematics | is there a mathematical theory that explains/predicts ‘good’ music? | There’s a mathematical analysis by Dimitri Tymoczko that investigates cross-cultural similarities in tonal music. | 22 |
d6fn2e | Technology | How can two videos of the same length and the same resoklution have different sizes? | Different encoding or compression protocols. Video isn't stored as raw data - those files would be massive for even short videos. Instead, the videos are encoded into different formats, which eliminate much of the raw data to reduce file size with differing effects of overall quality. Different protocols focus on different aspects of the video (and thus different raw data to remove), so they will have end results that have different levels of quality and file sizes. | 2 |
k4oub9 | Technology | Why does a cracked TV screen show a whole bunch of colors while a cracked phone screen does not? | My phone screens have done that when they break. There are two layers though, a layer of just glass and a layer of actual screen underneath, or digitizer or something. If you only break the top glass it just looks like a crack, but if you break the underneath, it gets all colorful. I imagine it’s the touch screen aspect that is the difference. | 1 |
646hai | Other | Where did the "S" rating originate and why is it better than "A+"? I've searched on google to no avail. | In Solo & Ensamble an S ranking means Superior and is the highest achievable, or near perfect. | 27 |
lyex9p | Technology | How do those walk-through scanners in libraries know if you're taking a book without borrowing it, especially if those books don't have metal inserts or anything like that? How does the library borrowing system work? and how come even if there is no obvious metal insert in the book those gates still know when and when not to beep if the book has or hasn't been borrowed? & #x200B; EDIT: Thank you all so much for the answers!! : D | The most well-known anti-theft device for books is a tape of magnetic metal strip. The tapes are applied between the spine and the binding of a book (for hard covers) or deep inside in between some pages (for paperbacks). It's called **tattle-tape**. | 11 |
l3k8r2 | Chemistry | Why use wax paper to line a cake pan? It seems the wax would heat up in the oven and mix with the cake batter. | You do not use wax paper in baking. You use parchment paper. Wax paper is a divider for use in freezing things. It is not for open use. | 4 |
ljnrc1 | Mathematics | what is mathematics? I take no credit for this question - saw a thread on Twitter that started with the question: If a child asked you, “what is mathematics?”, how would you answer? Just thought it was such an interesting discussion that it would be great to ask here! | My view: Mathematics is about trying to find out what unexpected consequences a set of rules has. The best way is probably to contrast this to some things. If we compare to other sciences like chemistry or biology, they are trying to find the rules based on which our world works. No-one knows the rules in full, which makes what they do different from mathematics. However, people have figured out incomplete parts of the rules, and they can use mathematics as a tool on those incomplete parts to try to further their understanding. Another interesting contrast is to other things which deal with rules, like for example law. Probably the biggest difference is that lawyers deal with rules that have grey area. There are many different shades of red and orange, and between them is probably a shade that you wouldn't be quite sure whether it is red or orange. But it wouldn't sound out of place if a law used a word like "red" or "orange". Mathematics, on the other hand, requires that the rules you deal with have no grey area. What this has to do with numbers, and the kind of things you're usually taught in "math class" in school: numbers, and their addition, subtraction, division, etc. is one of the most useful rulesets of mathematics, both in terms of applying to the real world, but also for understanding other rulesets within mathematics. That's why so much attention is placed on that single ruleset when teaching math. But it's of course not the only ruleset; for example geometry is another ruleset one might study, and mathematical logic would be another one. | 2 |
6xuejm | Other | Why does nobody play man to man defense in soccer? Watching soccer I notice nobody defends in a tight man to man defense (think basketball or ultimate Frisbee). I can see why man to man may not work with a slower team but you would think that with a very quick/physically gifted team man to man would put a lot of pressure on the opposing team causing a lot of turnovers. | For all the reasons everyone else has stated, but also due to the offside rule. If a defence was to play tight man-to-man, an intelligent attacking side could simply have one forward push his defender to the by-line (end of the field) and therefore open up the entire rest of the pitch for other attackers to exploit. Also, a soccer pitch is a much bigger area than a basketball court, has a longer active duration and of course doesn't have timeouts. To play man-to-man for a full 90 minutes would be exhausting and teams with fitter attackers would soon wear down defences. Teams do sometimes play man-to-man, but it's usually only against highly influential individual attackers in order to 'mark them out of the game'. | 5 |
72lpg5 | Technology | why do touch screens fuck up in the rain? | They sense the presence of something touching the front of the screen that effects electric charge. The tip of your finger does this, but so do raindrops. | 4 |
dy7zxy | Biology | How did people get enough food in pre-historic times I know that we've cultivated fruits, veg and berries to grow bigger and more nutritious over time, but how did people survive with so much more exertion and less beneficial foods. | Weren't as many people in pre-historic times so there wasn't as many mouths to feed. A forest could sustain a small tribe. Plus, they were nomadic and hunted for food. | 3 |
c1jls2 | Technology | How can apple trademark "apple" | Trademarks only apply within a specific industry or product type. They can trademark "apple" as a name for computer equipment because no one else was using it for that. They can't control its use for fruit, flavors or other unrelated stuff. | 2 |
o2wngy | Technology | What do people mean when they say you don't actually own the games you buy digitally? I guess this comes under both technology and economics. But yeah I don't get it. You pay money for a game, you now own that game. That's how a transaction works. If I don't own it what on earth did I pay all that money for? How can companies get away with this? | No, that's not how transactions work. For example, you pay to see a movie, you don't own that movie. You've paid for the right to see it once. You walk into an apartment and pay the landlord for an apartment, you don't own the apartment, you're renting it. It used to be you could go to the game store, buy the game and it was yours. Now (and especially with streaming and digital games such as you get with Steam) there are a whole hosts of terms and conditions you are agreeing to when you download the game. For a non-game example, I used to have a copy of a drafting software. I could load it up and use it whenever I wanted. It was, for all intents and purposes, mine. Well, it soon became out of date so I looked into purchasing a new version. Except the company that made it wasn't selling a new version, they were selling a license to use the new version for a monthly cost. And they get away with it because that's how things work. It's their software and they can sell, rent, and distribute it however they want. You aren't entitled to be sold something if they don't want to sell it to you. And when you see that big block of text and click "I agree" you are, in fact, agreeing to the terms and conditions under which you are accepting the software, which may include the fact that they are only giving you permission to use or play it, not that you outright own it. | 6 |
gsza50 | Physics | Why do dimpled golf balls go farther than smooth? I remember hearing that golf balls used to be smooth and people would actually play with old beat up balls because they would fly further than the new smooth ones. Why is this? What makes dimpled balls go further? | The dimples on a golf ball produce little pockets of turbulent air. These pockets of turbulent swirling air vortexes produce a boundary layer of air surrounding the ball that is _super smooth_ and slippery and this allows the ball+pockets+boundary layer to slip through the air. Boundary layers are fascinating stuff. There's a reason for [splitter plates]( URL_0 ) on jet fighters that have engine inlets midway down the fuselage - the boundary layer created by the nose of the aircraft makes for really turbulent air that jet engines don't like so much, so the plate diverts that away from the inlet. If your golf ball were super smooth the air would slip around the smooth body of the ball but as the ball passed there'd be a much bigger wake vortex behind it as the boundary air followed the curvature of the ball's surface around and the huge eddys produced would pull the ball backwards even, slowing it down. | 2 |
5lf0p0 | Culture | What was Nietzche's philosophy, exactly? I am at a loss as to what they mean. I'm having a hard time understanding concepts such as "God is Dead" or "Ubermensch" and only have a vague interpretation as to what they are. Any help will be gladly received so thank you in advance. | Nietzsche's "Ubermensch" is the goal that society should set for itself in the process of rejecting the morality of religion, particularly the Christian/Catholic Church. Nietzsche saw the Church's influence and power over society as the sick man's victory over the healthy man, as a real perversion, etc. In short, he wasn't a fan. "God is dead" is simply Nietzsche's way of saying that we do not have to rely on God to give meaning to life. And in effort to stave off nihilism, Nietzsche argues for the need of the "Ubermensch". The "Ubermensch" creates new values that must be motivated by a love of this world and of life. Whereas Nietzsche diagnosed the Christian value system as a reaction against life and hence destructive in a sense, the new values which the Übermensch will be responsible for will be life-affirming and creative. [Source]( URL_0 ). So rather than God giving us meaning to life, *we* give ourselves that meaning. Nietzsche kind of gets a bad rep, in some instances, as being this incredibly nihilistic person but in fact I think he was looking for a way to usurp the power of religion whilst also resisting nihilism and the concept of the Ubermensch was his attempt at doing so. | 11 |
6fqh4z | Biology | Why is it that every day at 2ish I hit a wall and feel so tired I could fall asleep in a trash compactor, but in 20 minutes I'm fine? | Do you drink coffee or take anything caffeinated in the morning? The same tiredness hits me as my morning coffee (8am) wears off around 2pm. | 13 |
7kpmv2 | Other | What's the difference between an anti-hero and a villain? | An antihero is a person who the audience or reader is supposed to identify with or support as a protagonist, but who doesn't have typical heroic qualities. Usually they're either doing the right thing for the wrong reasons or they're doing bad things for the greater good, whereas a typical hero is just doing the right thing. Think of The Godfather - the main characters are criminals and murderers, but we empathize with them and their situations, because they have some good motivations along with the bad. A villain is just a villain - they're the bad guy, they're the obstacle in the hero's way, and the audience or reader is not meant to support them, though they may have some empathy built in. | 3 |
j4h1a3 | Other | why can’t we domesticate all animals? | Saw a TV program on this issue some time ago. Turns out that for a certain especies to be domesticated it has to meet a few requirements. 1) They have to tolerate humans. If they are too stressed by our presence to carry out a normal life (feeding, mating, etc.) they are of no use. This should cover deer. 2) They need to have a shorter span of life than humans. This is because humans need to supervise at least the first domesticated generations. The reason is to use natural selection to get rid of unwanted traits / behaviours and the opposite, to see if they can get all the offspring to have the desired traits, like friendliness or more production of meat and fur. There were other conditions, but I can't remember them right now. I also can think of some exceptions to those rules, like domesticated animals (turtles, elephants) than can outlive humans. | 14 |
6i97fi | Culture | Why are most songs that come out 3-4 minutes long? | Song length has changed over the years. I am not sure why but for some song contests (like the Eurovision song contest) every song must be of a certain length with very little wriggle room. This graph shows how song length has changed with time: URL_0 | 4 |
f4zrmw | Biology | What is the biological purpose of crying when you’re sad? Is there a purpose? | Someone has already mentioned the small dose palliatives in tears, but that’s only part of the answer. Crying comes before language, and is a way for infants to communicate that they need something. | 6 |
78pnzo | Chemistry | Why do they say that the kitchen sink has more bacteria than your toilet? | Because ["The meat industry sued the federal government, winning the right to sell food known to be contaminated with food-poisoning bacteria."]( URL_1 ) edit: Why the down vote? Studies find more fecal bacteria in kitchens than in bathrooms precisely because our retail meat contains so much fecal bacteria: [Consumer reports]( URL_3 ):"All 458 pounds of beef we examined contained bacteria that signified fecal contamination (enterococcus and/or nontoxin-producing E. coli)." [J Appl Microbiol. 1998 Nov;85(5):819-28]( URL_0 ). Reduction of faecal coliform, coliform and heterotrophic plate count bacteria in the household kitchen and bathroom by disinfection with hypochlorite cleaners. [Appl Environ Microbiol. 2017 Oct 13. pii: AEM.01902-17. doi: 10.1128/AEM.01902-17]( URL_2 ) [Epub ahead of print] Prevalence and Antimicrobial Resistance of Enterococci Isolated from Retail Meats in the United States, 2002-2014: "Enterococci, including Enterococcus faecalis and E. faecium, are present in the gut of food-producing animals and are used as a measure of fecal contamination of meat. We used the large, consistent sampling methods of NARMS to assess the prevalence of Enterococcus strains isolated from retail meats, finding over 90% of meats to be contaminated with enterococci." | 3 |
mydw4b | Physics | Would the Earth's rotation slow down if we got everyone on the planet to run to the east at the same time? | On a technical level yes the rotation of the earth would change but the amount would be so small as to be undetectable. | 4 |
c1wkbe | Physics | How does “heat lightning” work? Why doesn’t it make thunder? | It does. You're just not close enough to hear it. "Heat lightning" is regular lightning seen from a distance, several miles away. You can still see the flash, but the sound dissipates before it gets to you. | 3 |
6ez3ds | Biology | why do gamers especially find themselves staying up well into the early hours of the morning? I have played games for many years and I find that each time a holiday roles around i will get up in the afternoon and play games up until about 3-4am. Why is this. For my friends it is the same and even though during the day we would not be doing anything anyway we seem to be subconsciously attracted to turning nocturnal over times when we have no reason to be awake in the day. Would we be all be nocturnal of it wasn't for our commitments during the days?(I'm writing this at 4:24am for me so I apologise for any spelling or grammar) | I stay up anyway, (6PM-6AM shifts at work), and even on my days off, I keep to my work schedule; there's nothing to go out and do at 3AM, so games filled the gap :) | 5 |
965lzf | Repost | Double Slit Experiment. I have a question about the double slit experiment, but I need to relay my current understanding of it first before I ask. ___ So here is my understanding of the double slit experiment: 1) Fire a "quantumn" particle, such as an electron, through a double slit. 2) Expect it to act like a particle and create a double band pattern, but instead acts like a wave and causes multiple bands of an interference pattern. 3) "Observe" which slit the particle passes through by firing the electrons one at a time. Notice that the **double band pattern returns, indicating a particle again.** 4) Suspect that the observation method is causing the electron to behave differently, so you now let the observation method still interact with the electrons, but do not measure which slit it goes through. Even though the physical interactions are the same for the electron, it now **reverts to behaving like a wave with an interference pattern.** ___ My two questions are: **Is my basic understanding of this experiment correct?** (Sources would be nice if I'm wrong.) and also **HOW IS THIS POSSIBLE AND HOW DOES IT WORK? It's insane!** | Typically a photon is used rather than an electron, since that makes figuring out the wavelength (which determines the pattern) a lot easier, but otherwise you got it right. As far as why it works that way, we have no idea. Well, we have lots of ideas, but no solid answers. We do know that if you split a photon into two entangled photons (each with half the energy) you can observe effects that appear to violate causality, in that measuring one particle ***after*** the other has gone through a double slit experiment changes the result of the experiment retroactively. Unfortunately it does so in a way that makes it useless for sending messages to the past. When someone figures it out that's pretty much a guaranteed Nobel prize. Edit: "appear to" | 11 |
a2e421 | Technology | Why are electric cars more eco-friendly if electricity is still fossil-fuel powered? If a normal car burns gas, I get why that's bad for the environment, and an electric car doesn't. But doesn't the power that charges electric cars still come from power plants that also are bad for the environment? How big is the difference in pollution? | Generally, electric cars use energy more efficiently than petrol cars. Also, coal and natural gas power plants usually implement expensive processes that clean up the by-products of burning fossil fuels before releasing the exhaust into the air. Petrol cars would be far too expensive if similar measures were implemented in every car so they tend to pollute heavily. | 5 |
6audcf | Other | Why do we tend to view mammals and furry/soft animals, even predators, with a positive physical connotation (cute, pretty, regal, etc) but scaly animals, insects, arachnids etc are viewed with a negative physical connotation (gross, ugly, fearful)? | Not really even sure how to flair this because I don't know if it's biologically driven, culturally influenced, etc. | 5 |
dbv6ui | Other | (At least in English) Why when followed by certain words (specifically I've noticed with anything that starts with "you") do words ending in "t" often end up sounding like "tch". For example; "I love that about you." often ends up sounding like "I love that aboutch you."? | It's the t to the y. Make a 't' noise in your mouth, your tongue is loosely at the roof of your mouth. Now make a 'y' noise; your tongue is on your front teeth. Now make a 'ch' noise, your tongue is midway between the two; as you transition from a 't' to a 'y' your tongue goes into the position to make a 'ch' and if you keep breathing out as you do then it makes the noise. | 5 |
7lai2x | Biology | Ketosis how does eating high fat diet make the body burn your own fat? i want to believe, but it's confusing.. | Getting into ketosis isn't necessarily the addition of fats, but the lack of glucose. When glucose enters the body, it is stored as fat. With the lack of it, the body burns the fat your body has stored instead of glucose. Also, keep in mind, all fats aren't bad like everyone makes them out to be. Monounsaturated Fat and Polyunsaturated fats can actually be very healthy for you in the right quantities. | 1 |
8cg0tb | Economics | In 1918, a $100 bill was worth about $1700 in today's dollars. What was the point of having such a large denomination bill? | Funnily enough, we actually did used to have thousand and 5 thousand dollar bills, back during the same time period. I imagine that they were primarily used internally in banks. | 5 |