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1rh855 | why does my hair take so long to dry? | After getting out of the shower it takes literally seconds to dry my skin, but why does hair remain wet for hours? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1rh855/eli5_why_does_my_hair_take_so_long_to_dry/ | {
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"Imagine your hair as a sponge, It absorbs the water, and with out squeezing it (rubbing with a towel) it stays absorbed to a maximum capacity. So more water is there to evaporate than if it wasn't as \"full\" of water, thus taking longer. As for the skin drying fast, A.) it doesn't absorb nearly as much water as hair and B.) water creates hydrogen bonds with your skin- hydrogen bonds are weak, and break by the heat of the friction when you rub the towel on your skin, drying your skin faster."
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2yajew | what exactly is happening when my iphone/computer starts up? why doesn't it just turn on instantly? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2yajew/eli5_what_exactly_is_happening_when_my/ | {
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"Most important/highly accessed parts of your system are loaded into ram. When you power your device off, the power stops getting supplied to your ram. Your ram is volatile, meaning it needs power to store things. So when you turn your device on, it needs to load it all to ram again. This takes time. Also, with computers, it checks every device to see what's connected to your computer, and loads the appropriate drivers for them. For iPhones, there's a huge variety of tests that happen on boot that makes sure your device hasn't been modified.",
"There is a sequence that always happens during startup called POST. This stands for \n\nPower\n\nOn\n\nSelf\n\nTest\n\nThe main components in the device are booting up and making sure that they are functioning correctly. After this process, the OS, or Operating System, is being loaded from the storage device, with the required processes being transferred to the RAM, as it is not an offline storage device and is cleared when powered down.\n\nThe speed at which the OS loads varies depending on the storage device and the OS itself. \n\nAfter this is done the UI, or User Interface is shown on the screen. This is the graphical interface that the user (You) are familiar with.",
"It has to boot up the operating system first before you can do anything with it.\n\nWhen you computer or device starts up it needs to have some sort of plan what to do. It needs to have an idea about how to react to various inputs, like if my user presses that button I am going to open that window etc.\n\nIn the old days computers often were simple enough that they were ready to be used the instant you turned them on. My old C64 computer told me it was ready almost as soon as I clicked the power switch, but it had a very limited amount of things it could do.\n\nNowadays computers are more complex and need more instructions on what to do. Getting these instructions and commiting them to memory takes time.\n\nWhen you turn on a computer there are a number of different steps it goes through like getting the hardware ready figuring out what to do next. In most cases the next part is loading an Operating System like Windows or Linux from the main disk.\n\nModern operating systems are big and can take some time to read from disk even if the disk in question is not an actual disk anymore but a fast and non disk shaped SSD. What is worse is that simply loading the OS from disk into memory is not enough (When windows returns from hibernation this is what it does, which is why this is so much faster than normal starting of a computer)\n\nVarious steps have to gone through like loading drivers and starting services. Drivers are small programs that run in the background and deal with (mostly) hardware like your mouse or your graphics card or your display. Services (or daemons in the linux world) are programs that run continuous in the background and take care of various tasks.\n\nStarting all these and much more and making sure that it runs the way it is supposed to can take time."
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4g3jw8 | why most of news companies using "times" or times-based word as their brand name? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/4g3jw8/eli5_why_most_of_news_companies_using_times_or/ | {
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"In the past, \"times\" meant something close to \"things that happen\", or \"current events\". We also see it still used in phrases like \"sign of the times\" or \"behind the times\"."
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1szu8u | if a director of a film shoots 35mm film, how on earth do they put cgi onto the film negative if its projected in the same 35mm format? | Photography degree graduate here, after years with 35mm, I still have no idea how they do this? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1szu8u/eli5_if_a_director_of_a_film_shoots_35mm_film_how/ | {
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"4 steps:\n1. Shoot on film \n2. Convert to digital format for editing (telecine)\n3. Edit and insert effects and CGI\n4. Convert back to film using a high-tech machine \n",
"It depends on a few things.\n\nIf you mean before there were digital effects, they would usually composite their effects after a rough cut of the movie directly to the 35mm roll and would copy that over to a new roll.\n\nIf you are talking about during the digital effect days (last 20 years), they do 1 of 2 things. Either:\n\n* They digitize the raw footage, do the cutting and effect compositing on a computer, and then put the finished product back on a 35mm role.\n\nOr\n\n* They forgo using 35mm in either the finished cut or won't use it at all.\n\nMost movies nowadays, from shooting to post, use a completely digital recording setup and don't even touch 35mm. If they end up recording on 35mm, they will just digitize it and put the finished cut on some digital storage medium. Most theatres don't even use 35mm projectors anymore.\n\nSource: Film class for 4 years, dad a camera guy, multiple friends whom work at theatres, film nut in general. \n\nThis MAY be a bit much for a ELI5... \n\nEDIT: If someone could check my accuracy, I would appreciate it.\n\nEDIT 2: Spelling and formatting, originally written on my phone."
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5i2cfw | what are the practical differences between 256-bit, 192-bit, and 128-bit aes encryption? | I just got a VPN and I want to know how to get the absolute most out of the service but im not sure about which Encryption setting is the best. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/5i2cfw/eli5_what_are_the_practical_differences_between/ | {
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"More bits = slightly slower encryption but more secure, since an attacker has more bits to break.\n\nIn practice, AES works by dividing the input into blocks and performing some repetitions of transformations on each block. The number of repetitions depends on the key size: 10 repetitions for 128-bit, 12 repetitions for 192-bit and 14 repetitions for 256 bits. So this makes a 256-bit encryption 40% slower and computationally extensive than 128-bit encryption, however it is quadratically more secure.\n\nSo unless you absolutely positively need high performance, go with the most bits."
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obs2o | el5: the benefits and downfalls of the federal reserve. | I really agree with a lot of Ron Paul's stances, but I feel the majority of my sources on this topic are heavily biased in one way or another. So, simply stated, what are the benefits and downfalls of the federal reserve? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/obs2o/el5_the_benefits_and_downfalls_of_the_federal/ | {
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"The [Federal Reserve](_URL_0_) conducts the monetary policy of the United States and has a lot of control over the dollar, our form of money. The Federal Reserve has 2 main responsibilities - maximum employment, and stable prices. The Federal Reserve has a lot of control over banks and lends them money periodically, and it also determines how many dollars should be available in the economy.\n\nThe benefits are that it has a decent (though imperfect) track record at dealing with recessions and economic downturns. It's easier to manipulate the money supply to fight recessions than it is to convince Congress to spend lots of money building things, so the Fed is a good tool when unemployment is high. Further, the Fed conducts quite a bit of research into the economy, making informed analysis a lot easier.\n\nOn the other hand, many people (such as Ron Paul) view the Fed as unaccountable and undemocratic. The structure of the Fed is such that they don't typically require Congress to approve their actions, and they often don't feel the need to explain their actions to the general public. The Federal Reserve is also not expressly authorized in the Constitution, a sticking point for Ron Paul in particular, and Constitutionalists in general.\n\nFurther, the Fed often induces inflation, or makes the dollar weaker, in efforts to fight unemployment. Many, such as Ron Paul in particular, view inflation as a chief concern of the economy, and say that a return to a harder money standard (like the gold standard) is necessary to fight off inflation.\n\nSo the Fed is generally effective at moderating our financial system and at keeping unemployment low, but (in the eyes of some) it could do more to fight inflation.\n\nHopefully that helps.",
"Benefit: Someone needs to control the money supply. The Fed is autonomous, meaning Congresa has no control over money supply. If the Fed is dissolved like Ron Paul suggests, who would control the money supply? The obvious answer would be Congress. 1. Could you trust our Congress with something as important and complex as the money supply? 2. Congress would have the power to run a deficit (as they do now) and \"print money\" to support the spending. So if you trust Congress to not abuse this power, then it everything would be ok... But let's be honest, they couldn't handle the responsibility."
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ziitg | why napster got sued but utorrent and others are still fine? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/ziitg/eli5_why_napster_got_sued_but_utorrent_and_others/ | {
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"Napster was one centrally located server whereas utorrent is just an application that you use to connect to any of the millions of torrent tracker servers out there. It's as if there are millions of Napsters out there now instead of just the one. And those DO get shut down, it's just that there's so many of them and when one gets shut down, another 5 pop up to replace it. \n\nOn top of that, the uTorrent application is perfectly legal, it's what can be downloaded using it that is illegal.\n\nTL;DR - Decentralization.",
"A copy of uTorrent alone isn't enough to pirate content - you need to provide it with the torrents.\n\nA copy of Napster alone was enough to pirate content, you could get everything from right within the application.",
"The moment uTorrent itself provides copyrighted material for download, it will be open to a lawsuit.\n\nHowever, it never will. The user is required to go one step further on his or her own and download the material, and in order to do so, they must go outside the application. That small degree of separation may seem insignificant, but pick any analogous situation you want, and you'll see why it's important.\n\nWith Napster, it directly enabled you to download copyrighted material, without going one step further outside the software.\n",
"uTorrent is like a bong. It's just a device to smoke (download) from. When you choose to smoke cannabis from it (download unauthorized content) it is illegal.",
"If you think of illegal filesharers as burglars, Napster was a guy who'd broken into a really nice house and handed out free stuff to passers by. BitTorrent clients are just a really good crowbar; you can use it to open crates of things you're allowed to have for free but you can also choose to use it in burglaries.",
"There is no case against UTorrent, because they don't have any control over the content whatsoever. They are literally just implementing an open transport protocol invented by Bram Cohen. If you sue any number of the players, it would do nothing to the network.\n\nIn the case of Napster, they were a corporation that ultimately actively encouraged the piracy of music. I.e., there was someone to sue who was a single point of failure. Once Napster was shut down, the network shut down as well, because it operated with an IRC-like central server.\n",
"Bittorrent is a method of transmission. Like using your mailbox. You can do illegal things with mail, but, that doesn't make mailboxes themselves good or bad. ( uTorrent is a bittorent client )",
"Napster got sued because one night when I was out partying with The Offspring in Edmonton, Alberta during a tour back in 1998 or 1999 (date is vague-- it was the pretty fly for a white guy era/tour) I walked up to Dexter and said, \"I have all your albums\". He responded, \"That's great man\"! To which I replied, \"On MP3\". I received a puzzled look.\n\nA week or so later The Offspring started selling Napster T-Shirts on their website stating, \"If you're going to steal our shit, we're going to steal yours\".\n\nI killed Napster. True story.",
"OK, so you wanna trade Pokemon cards? Awesome.\n\nIn Pallet Town, everyone who wants to trade has to go to the Napster building. There are tons of little trading rooms, and you ask the nice lady at the front \"I want to trade my Blastoise for a Charizard\". She tells you what room to go to to find someone who has a Charizard.\n\nBut over in Viridian City, everyone trades cards in their back yard. However, you have no idea where any traders are, and what they're trading.\n\nSo they make business cards, and stick them all up on a bulletin board, which someone called The PokeBay for some reason. But the business cards are all written in CODE! You need to use your Pokedex to translate them. You go there, and you see a message that says \"Trading Charizard, come to 123 Fire-Type Street. Ask for Gary.\"\n\nSo you head on over to 123 Fire-Type Street, find Gary and proceed to beat the snot out of him for being such a giant dick to you all the time. And then you trade for his Charizard.\n\nBut OH NO! The Elite 5 have declared that trading cards is against the rules! And they're going to stop any traders they can!\n\nFirst they blow up the Napster Building! Suddenly, nobody in Pallet Town can trade anymore.\nBut over in Viridian City, they can't find where people are trading. They translate a couple cards, and they put Koffings in their backyards and go \"That'll show em\", but they can't track down everyone, so eventually they run out of Koffings and give up.\n\n---------\nWhy you can sue Napster: It's all in one place. When you shut down Napster, you shut down the whole thing. Napster was specifically connecting the file traders. Also, it was a single business.\n\nuTorrent is not a business, it does not connect people... it doesn't actually do much. It is just a translator for certain files. Nothing illegal about that.\n\n---------\nTranslations:\nTrading cards = copying stuff \nBack yard = personal computer \nBusiness cards = .torrent files \nPokedex translation = uTorrent \nThe PokeBay = you can figure this out \nKoffing = lawsuit\n",
"Okay, a lot of people seem to be missing the point here. It is not a matter of torrents or no torrents, it is the software used to download the files. I'm not entirely sure about the Napster case, because I didn't pay a lot of attention to it at the time, but uTorrent does not give you the music and there is nothing illegal about .bit torrent clients. Take a hookah for example. The hookah itself is not illegal, just some of the things you can smoke with it. uTorrent is essentially the hookah of P2P, in the sense that torrents aren't always illegally pirated files, but they are also sometimes legitimate files such as Linux ISOs and other OSS. If anything, .bit torrent clients would not get sued, just the sites that offer the content (i.e. TPB, kick ass torrents, etc.).\n\nI'm not sure if that clears anything up, but I hope I offered a little direction.",
"this subreddit really has turned into /r/answers",
"like your five: well, because sweetie, the two are not like each other in any way at all, not even a little bit."
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45vpj6 | if you ate lots of fat, but no carbs whatsoever, would you gain weight? | By this, I mean drinking a whole bottle of oil and consuming nothing else in that day. I thought that carbs were needed in order for the body to use energy, but perhaps I'm mistaken. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/45vpj6/eli5_if_you_ate_lots_of_fat_but_no_carbs/ | {
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"What you've just explained is pretty much ketosis. Although you exaggerated a bit by saying drinking a bottle of oil and no carbs, a ketogenic diet relies on a low carb, high fat, high protein diet. This leads to losing weight. If you want to read more, go to /r/keto.",
"Weight gain depends on the amount of calories consumed in relation to each individuals daily caloric requirements. If I am consuming calories under my total daily energy expenditure I will lose weight.\n\nIf I lose 2lb a week consuming 2000 calories a day I don't think it matters where those calories come from. I would feel like shit though.",
"simply put.. yes. if the amount of energy in a bottle of oil is more than the amout of energy you expended that day..\n\nhowever, you'd put on less weight that you would have done if you'd consumed the same number of calories of carbohydrates. \n********** \nRest of post deleted due to people thinking eli5 is /r/science \n*******\n",
"Er... its complex.\n\nSimply put, yes ofc, there is a high caloric amount.\n\n\nHowever speaking of weight loss in general, its a bit more complicated due to insuline cycles/spikes. \nsimple carbs (and protein to an extent) cause high insuline spikes which cause a hunger cycle, and make the body store energy into fat as it tries to get rid of the sugar in the blood stream (its bad, look at diabetics to understand the effects of high sugar in the blood).\n\nSo, 500calories of fat might not be as fattening as 500 calories of pure sugar, also depends on how spread those calories are... Then also depends on the effect of said food into your gut flora which then affects digestion, also not all sugars are the same, fructose for example is metabolized differently (via the liver) which is why its considered \"safe\" for diabetics (arguable) due to it, it also can cause liver damage (google fructose cirrhosis).\n\nIts complex, for most purposes we just say calories is what matters, but deep deep down, eeeh, not all calories are the same. \nThen it also depends on your individual biochemistry, how your gut health is tgys how you absorb and utilise said nutrients. \n\n\nFrom experience: Avoid simple carbs like the plague, they cause a lot of issues, if all you care for is weight loss, either is fine, count calories and be at a deficit but focus on complex carbs. ",
"Your body can make every carb it needs without ever eating a carb/sugar. If you drink nothing but oil, after a few days your body will start burning fats for energy.\n\nTo answer the weight gain part. Yes. If you consume enough calories of anything, including oil, you'll gain weight.",
"Simply put, you didn't give us enough information. Either way a diet of entirely far or entirely carbs will kill you. But weight gained comes down to calories in vs calories out. If you eat 2000 calories and burn 2100, it doesn't matter if the calories came from fat or carbs, you're losing weight. "
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fxe6g9 | with the air cleaning up nicely throughout the world, where exactly does all the smog/soot go? | [deleted] | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/fxe6g9/eli5_with_the_air_cleaning_up_nicely_throughout/ | {
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"It settles on things, gets caught in things, and lots of places have smog traps that are just giant air filters. Think about any dust or dirt in your house, it settles somewhere eventually. CO2 of course is different and is absorbed by trees."
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3dbhpw | why is it easy to convert binary into hexadecimal? | Say i have the binary number 1111 1111 1111. Converting this into hex easily gives me FFF. But why? Why is it okay to just split the binary into sets of 4, find the hex number for each set and just combine them? Isn't the 1111 furthest to the left different than the 1111 furthest to the right?
Why is this not okay to do with decimal. 1111 1111 1111 becomes 151515. But that's incorrect.
| explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/3dbhpw/eli5_why_is_it_easy_to_convert_binary_into/ | {
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"Because binary is base 2, so if you go 4 number places out in binary that represent the number that is up to 2^4 = 16. Hexadecimal represents numbers in base 16, so whatever number that group of 4 numbers in binary is represents a single number of hex. Decimal is base 10 which does not have a whole number of binary digits (2^x = 10, x is not a whole number)."
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5wo9db | why does wikipedia deem references to primary sources as unreliable? | I was reading an article about Visual Basic and the banner at the top asked for help editing in more secondary and tertiary sources, as the article relied to heavily on primary sources.
_URL_0_
In all my time in academia, the preferred source of information was primary sources, as they were the most reliable and closest to the event or topic in question. Why would an overabundance of primary sources be an issue for a WikiPedia article? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/5wo9db/eli5_why_does_wikipedia_deem_references_to/ | {
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"In the world of academia, the person writing the article or paper has an education and background in the field in which they're writing, giving them the knowledge and understanding of the source material required to write about it. \n\nWith Wikipedia, no such background can be reliably proven. So if you cite sources that *do* have a proven understanding of the existing primary sources, you're more likely to have a feasible encyclopedic article (as opposed to an academic one). ",
"Because Wikipedia articles are supposed to present synthesized information, for which one needs to draw conclusions from the primary literature. Wikipedia editors cannot be trusted to have the expertise to do this properly, so Wikipedia prefers using sources in which experts have already synthesized information from the primary sources.\n\nThere is a rule on Wikipedia that articles cannot present conclusions not explicitly stated in the sources - Wikipedia is an aggregation and distillation of knowledge, not a place knowledge is created. Primary sources do not present conclusions about themselves, so if you want to write a substantive Wikipedia article while following the \"no conclusions not stated in sources\" rule, you will need to rely mostly on secondary and tertiary sources."
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1yvydt | why does computer memory capacity increase in multiples of 2? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1yvydt/eli5_why_does_computer_memory_capacity_increase/ | {
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5ix9tg | why are our legs inverted compared to our arms or others animals legs ? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/5ix9tg/eli5_why_are_our_legs_inverted_compared_to_our/ | {
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"Look at a dog.\n\nIt may look like it has a backwards knee, but it doesn't. The knee is much higher than you think. What you think is a knee is actually the ankle, because the dog is a digitigrade (\"finger walker\"), and could be considered to always be walking on tippy toes (though shaped to be many times more efficient).\n\nA raccoon, on the other hand, is a plantigrade. So are we.",
" > and other animals knees bend behind them (horse, feline, ostrich)\n\nActually, they don't. Other animals' knees bend in front of them, too. The joint that you're assuming is their knee is actually their *ankle*. Check out [this illustration of a cat skeleton](_URL_0_). Notice that the knee of the hind legs is up almost inside their torso, and the joint that you've been calling their \"knee\" is actually between the tibia/fibula (bones in the bottom half of the leg), and the tarsus (the heel bones of the foot).",
"As others have pointed out, you were confusing those other animals' ankles for knees. A way of thinking about the similarities that we share with them all is the pattern \"1 bone, 2 bones, lotsa bones, digits\" (moving from the torso out). In the human leg that's femur, tibia+fibula, wrist/hand bones, fingers. In our arm it's the humerus, radius+ulna, ankle/foot bones, toes.\n\nBirds' legs and wings, bats' legs and wings, dogs, cows, it's all the same thing for quadripeds. \n\nBy the way, check out the difference in how birds parcel out these bones within their wings compared to how bats do. It's an excellent illustration of how two different lines (the former are dinosaurs and the latter are mammals) each independently evolved its own approach to the same environmental niche (i.e. heavier-than-air flight).",
"Most 4 legged animals, at least the ones we're most commonly around, walk on their toes rather than the heel like us. It just looks like they have a tiny foot and a backwards knee.\n\n[Heres a useful colouration of the different bones cross species](_URL_0_) which demonstrates the type of leg structure you're talking about.",
"Stand on your toes. Now your knee is \"bent backwards\" too. The paw is the ball of your foot, must animals just have much longer feet than we do.\n\nAs to why, so they can run faster. "
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6sf2av | why does a baseball traveling towards you fly farther when hit than a stationary one? | It seems like the movement vectors of two objects traveling towards each other should subtract each other, making the baseball with a negative movement vector travel less distance than a baseball with one of zero. Also, following this logic, a baseball traveling away from you should go farther than both the stationary one and the one moving towards you (as the vectors should combine), but this doesn't seem to be the case. Why is this? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/6sf2av/eli5_why_does_a_baseball_traveling_towards_you/ | {
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"When the baseball is thrown towards you it has a certain amount of kinetic energy. When that ball hits the bat it transfers the kinetic energy into the bat. But, the bat doesn't simply absorb all of that energy. Most of it is reflected back into the ball. So, that reflected energy is added to the amount from the swing itself.\n\nImagine if you threw a baseball at a brick wall. The ball wouldn't simply stop dead, it would bounce back towards you. The same thing is happening with the bat but the difference is that bats are specially designed to reflect as much energy as possible. That's why metal bats hit farther than wooden ones."
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8nd0nz | how is the tissue folded to perfectly fit the box? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/8nd0nz/eli5_how_is_the_tissue_folded_to_perfectly_fit/ | {
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"Have you considered that the box is actually assembled/built around the tissue by a machine?",
"By a robot.\n\nTissue comes off the roller as one long stream, and is then cut into squares. These squares are offset on the conveyor belt, which then drops them into a stacker half-by-half. Once a complete stack is created, the box is slid over the stack from the side and the flaps are glued down."
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1ssm51 | the obamacare birth control mandate. | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1ssm51/eli5_the_obamacare_birth_control_mandate/ | {
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"Put in place by the US government to force health insurance providers/employers to include different methods of birth control on their employees plans at no cost to the employee. It stated that the mandate required all health plans to cover all contraceptives approved by the FDA. It covers pretty well anything you can come up with",
"It defines birth control as an essential health service. Health insurance plans are mandated to provide essential health services."
]
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[],
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dv3qhc | how do the openers on soda cans keep the can from cutting you when you drink from it? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/dv3qhc/eli5_how_do_the_openers_on_soda_cans_keep_the_can/ | {
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"The metal on the lip is beveled as part of the manufacturing process. That section also contains more of some element (i think molybdenum?) That allows the removed section to not shear off but rather detach under force."
]
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||
7up2xt | why is the moon bright some nights, but other nights it's not as bright? | I want to say it's got something to do with the suns refraction... but i need an ELI5 | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/7up2xt/eli5_why_is_the_moon_bright_some_nights_but_other/ | {
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"The Earth Sun and Moon move with respect to each other which in turn causes different amounts of light to reflect back towards earth. \n\nWhen the moon is full for example that’s the maximum surface area taking in the maximum amount of light. But also the moon isn’t a full circle, it’s an ellipse which means it isn’t always the same distance. When it’s closer it’s brighter and when it’s farther it’s dimmer. ",
"If you mean general brightness, outside of the cycles of the moon, crescent, half, full and so on, you know just one night you think it's a lot brighter than the next, that's most likely just due to high thin cloud level, and general haze in the atmosphere. This is the sort of thing that makes the day seem very, well, hazy; makes distance look washed out and indistinct. That same thing can have an effect on the perceived brightness of the moon. "
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19dceh | what's the difference between an empty set and 0? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/19dceh/whats_the_difference_between_an_empty_set_and_0/ | {
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"The empty set contains nothing. It's not a number, it's a group of 0 things.\n\n0 is a number.",
"It's like asking what's the difference between a box with 6 apples in it, and 6. The empty set is a collection of no elements. 0 is the number of elements in the empty set.\n\n**Aside**\n\nFormally, there is no difference. Mathematically, in order to make sense of the natural numbers, they need a definition. The currently accepted definition **is** that 0 = the empty set. \n\n_URL_0_\n\nYou can read more about it there. In common usage, however, they are different. This is just an example of set theoretic pedantry (which is why I dislike set theory :) )",
"The same difference as have a bank account with zero dollars in it, and not having a bank account."
]
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7kpalk | what are lagrange points and how do they work? | Wikipedia has failed me in making the concept understandable. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/7kpalk/eli5what_are_lagrange_points_and_how_do_they_work/ | {
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"It's 1am here so this might be a little oversimplified and weird; lagrange points are points in space where gravity of different celestial objects cancel out. You might know that larger masses cause a larger gravitational pull. Also, gravitational pull is quadratically inverse to distance, meaning the further away you are from a body the less attraction you will feel. At certain points in space gravitational pull of objects will cancel out because the masses and distances are just right. E.g. There are lagrange points between the moon and the earth. The most obvious one is l1 (lagrange point 1). If you draw a straight line between the center of mass of the earth and that of the moon you will find l1 lies on this line (a couple thousand kilometers from the moons center of mass). Hope this helps and my spelling is not too shit ",
"So first of all, all objects have a gravitational pull. This just means that all objects are constantly pulling on everything around them. The larger the objects, the stronger the pull.\n\nUsing the Earth and the Sun for an example, both the earth and the sun are pulling on each other at all times. They're actually pulling on each other with the same amount of strength, but the sun is much more massive, so it doesn't really move that much. The earth on the other hand moves a lot, so the earth looks like it's orbiting the sun\n\nBut now that we've established that everything can pull on each other, let's imagine that there's a tiny satellite next to the earth. It's small enough that it doesn't really have any pull on the earth or the sun, but it is influenced by both the earth and the sun.\n\nThe lagrange point is the location where, if a satellite were placed, the pull of gravity from the earth and the pull of gravity from the sun as the earth orbits the sun would keep that satellite in the same place relative to the earth. So it would orbit with the same period around the sun as the earth does.\n\nLet's draw a circle, with the sun at the very center and the earth on the edge somewhere. Now draw a line from the earth to the sun, and draw a point somewhere on that line closer to the earth than the sun. As the earth moves around the circle, so does the line. That point on the line is one of the lagrange points, and it will always be on that line between the earth and the sun.\n\nThere are a total of 5 lagrange points, in different spots around the circle, which always orbit at the same rate as the larger objects",
"There are five Langrangian points in a two body-system and they all work in different but similar ways but they do all have one thing in common, an object in these point share orbital speed with the small body around the larger body. To understand these you must first understand that orbital speed depends on mass and distance.\n\nThe first L point is the easiest to understand and is located between the two bodies. If we place an object closer to the large mass it will have to orbit faster to not spiral inwards, but because the smaller mass is further out that mass will pull the object outwards a little bit and will therefore decrease the orbital speed.\n\nThe second L point is located a little further out than the small object. Because it's further away from the large mass it should require a slower orbital speed than the small mass, but since the small mass is also pulling the object inwards the orbital speed becomes faster.\n\nThe third L point is located a little further in than the small body, but on the other side of the large body. The combined mass is higher so one might think intuitively that it should be further out than the small body, but accurate calculations show that is not true.\n\nThe fourth and fifth L points are symmetrical and lie in the orbit of the small body but a little further ahead or behind. The two bodies and the object will form an equilateral triangle and the reason these two L points exist is that once again the gravitational pull of the two bodies cancel out to give an orbital speed equal to that of the small body.\n\nOf all these points only 4 and 5 are stable."
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1wqx1j | how can i drink from bottles faster if i "shotgun" them with a straw? | Why does the beer seem to come out faster than if i wasn't using a straw and just drinking normally? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1wqx1j/eli5_how_can_i_drink_from_bottles_faster_if_i/ | {
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"text": [
"When using a straw, you allow air to take the place of the liquid you are removing, without interrupting your drinking."
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2c7np5 | how much radiation does a microwave emit? what about cellphones too? is it enough to be significant or harmful? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2c7np5/eli5_how_much_radiation_does_a_microwave_emit/ | {
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"No, both are non-ionising radiation and can't harm you in the way that X-rays can, if that's what you mean. That means they do not carry enough energy to strip electrons from atoms as ionising radiation does, which can cause genetic damage, radiation sickness and cancer if you're exposed to enough of it.\n\nMicrowaves can burn you of course, but that's different. Don't put your body parts in a microwave.",
"Exposure to a running microwave oven without the shielding door can lead to burns, but otherwise they are quite safe. Your cell phone presents more of a choking hazard than a microwave radiation threat."
]
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z9bmr | why are some programs compatible with windows xp/vista, but not windows 7? | I mean, this just bugs the stuffing out of me. I can't do half of the things I want after getting my computer fixed and they courteously put Windows 7 on it. | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/z9bmr/why_are_some_programs_compatible_with_windows/ | {
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"Because the programmer didn't update it. Most programs will either be updated, or run so they can run on either XP/Vista, 7, and even 8. It's just some expect Windows to be laid out a certain way and 7 is not laid out that way, so they can't work on 7. It's the developers of the programs fault, not Windows."
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77jisk | how does global population work? | Does the global population steadily increase every day? If so, are there ever natural disasters/manmade disasters that have ever affected this? How long can we continue on approximately until it becomes an actual overpopulation issue? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/77jisk/eli5_how_does_global_population_work/ | {
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" > Does the global population steadily increase every day?\n\nYes that is generally how that works.\n\n > If so, are there ever natural disasters/manmade disasters that have ever affected this?\n\nThe World Wars did a pretty big number, and it's possible that a significant event could impact the number slightly. But remember that we're talking a bit over 7 Billion people. A few million dead is pretty much a rounding error.\n\n > How long can we continue on approximately until it becomes an actual overpopulation issue?\n\n\"It depends\". With sufficient food and resources there is no hard cap, but in practice it is estimated that the world can sustain roughly 10 Billion people from a food perspective.",
"1) Yes, it has been increasing steadily for many years. Basically, more babies are born in a given day than people dying. The average couple on earth has more than 2 babies, so this nets out to more people. With people it's not 1+1=2, it's 1 + 1 = 4.25 (one couple produces 2.25 kids on average). \n\n2) Yes. The Bubonic Plague, for instance, is thought to have decreased total population on earth. \n\n3) You could say we already have overpopulation issues. India and China already have more than a billion people each. There are famines in Africa, i.e. the local population outstrips the food supply. And so on. There's no hard answer to this, and there is no single number at which the earth will shut down and people just start dropping like flies. \n\nThe good news is that population is expected to level off around 9 billion sometime this century. The bad news is that's a ton of people and there's no guarantee that we'll have enough food, water, and clean air for everyone. \n\nOverpopulation issue means quality of life declines or people start dying due to population-related issues. In that sense we've had overpopulation issues for a long time. The real question is how much worse they'll get before they get better - if they ever do. ",
"It increases constantly and this is an excellent sit which shows a count as it happens for the world and for each country.\n\n\n_URL_0_\n\n\nOverpopulation is already a problem because we are driving other species to extinction and are using renewable resources up faster than they can be replaced. It's just that right now we haven't really felt the pinch, but we know it's coming. I cannot remember the site but there is something about at what point during the year do we use up the resources we have produced that year.. and each year the date is getting earlier and earlier.. \n\nJoin /r/overpopulation for more help",
"An important fact is that while many nations have an increasing population, the increase is from the drop in childhood mortality. Since they did not die those children are getting older, and older. The population of a nation will increase. But fertile women in those countries are only bearing about 2 children, replacements.",
" > If so, are there ever natural disasters/manmade disasters that have ever affected this?\n\nGenetic evidence suggests there was an major reduction in the human population 75,000 years ago. It's believed that this reduction was caused by Toba, the largest volcanic eruption in human history and one of the largest in the history of the planet. The planet cooled by 3-5 degrees C for the next 200 years. More details [here](_URL_0_)"
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2o5sz1 | why does israel spy on the us? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2o5sz1/eli5_why_does_israel_spy_on_the_us/ | {
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"Everyone spies on everyone as much as they are able if they are smart.\n\nMaking decisions requires information. If you don't have correct information then you are less capable of making the right decisions. Therefore if you value making the right decisions then you must also value pursuing accurate information, even if those people with the information don't really want you to know. You see, the people making the decisions swore an oath to their own people and owe it to them to make the right decisions, and they don't owe the people who want to keep secrets anything at all.\n\nThis is why everyone has spies of varying ability, even if nobody wants to talk about it.",
"Why does the U.S spy on Israel? why do we spy on Germany and vice versa? we and us, and every other country wants to learn things before its publically revealed as a means of leverage. You think their aren't British spies on U.S soil right now?"
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7mjqzx | does milk bond to chocolate? why doesn't the chocolate settle to the bottom of pre-made chocolate milk at the grocery store? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/7mjqzx/eli5_does_milk_bond_to_chocolate_why_doesnt_the/ | {
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"It depending on what type of bonding you mean. \n\nWhat is occurring that the many different compounds are in a type of \"suspension\" within the liquid. These molecules fall between a gradient of [*homogenous* (same-type, same phase, distributed evenly), and *heterogenous* (different type, same phase, distrubited unevenly)](_URL_0_) suspension. For this to occur, there are many little forces pushing and pulling on each other molecule, holding everyone in relative stability. This means that your little bits of chocolate aren't bonded by strong forces, but being held by weak intermolecular (between molecules) forces between the water, proteins and other little bits. \n\nIt does not settle to the bottom at the grocery store because they have increased the *Viscosity* (how runny it is) of their milk. This can be done through many many ways (such as adding fats, starches, proteins, or gelatin (technically a jumble of organic material), etc). The molecules have less ability to lump together, because they are thoroughly mixed and inside a viscous liquid medium. \n\n"
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2ama7n | how do scientists usually estimate very, *very* large numbers (e.g. number of stars or grains of sand on earth)? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2ama7n/eli5_how_do_scientists_usually_estimate_very_very/ | {
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"It isn't difficult to estimate the number of grains of sand on the earth. We know roughly where sand is and how many grains there are in specific volumes like a teaspoon. We know how many teaspoons there are in a cubic meter. Sand can't hide. We can see how deep it is on the ocean floor with sonar. If its buried for a long period it becomes rock. Its just multiplying it out after that. \n\nWe can do similar things with the number of stars in a galaxy. Its not difficult to count all the stars in a region, estimate the population in similar regions and just add it up. \n\nAs for really big estimates like how many stars there are in the universe, or how many galaxies. That's more complex and requires some guesses about how the universe is composed and whether its infinite or not. Just based on fairly straightforward info like the redshift of distant galaxies we can sorta tell that the universe is at least 90 billion light years across even though its only 13.78 billion years old. That may seem like a contradiction but it got bigger very early on.",
"By using multiple \"estimations\". We can tell how many grains of sand are in, say, a cubic meter. We can tell how many square kilometers of beach are on earth, and we can measure their depth. So if there are 10,000,000 grains of sand in a cubic meter and there are 100,000 km (100,000,000 meters) of beach on Earth averaging 10 meters deep, we can estimate there are about 10,000,000,000,000,000 grains of sand on Earth.\n\nI completely fabricated those statistics, but you get the point."
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aedkf9 | why is so hard to breathe with just your head out of the water ? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/aedkf9/eli5_why_is_so_hard_to_breathe_with_just_your/ | {
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"The water pressure on your chest makes it harder for your lungs to expand to let in more air. This is more apparent when you try to breath from a pool noodle from farther below the water.",
"You breathe by using your diaphragm to increase the volume of your chest cavity, which lowers the air pressure in your lungs, which means that air pushes into your mouth to fill them and equalize.\n\nIn the water, you have to push out against the weight of the water instead of against the weight of the air to expand your chest, which makes it harder for them to expand to the same volume."
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45pg5g | what are the pros and cons of the uk leaving the european union? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/45pg5g/eli5_what_are_the_pros_and_cons_of_the_uk_leaving/ | {
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"One of the biggest factors is trade. The UK being within the EU allows free trade within member states, which is a great perk, however it makes it significantly more difficult to trade with outside nations, such as China. \n\nAnother con is the member fees the UK pays to Brussels is enormous, although they do recieve some of it back in subsidies.",
"Pros of leaving: They will better be able to control their borders. They will no longer be paying dues to the EU. They will be able to set more tariffs on imported goods. \n\nCons of leaving: Their citizenry will no longer be able to freely travel around Europe and so would need to get tourist visas. Their citizenry would not be able to work in other EU countries without getting work visas or fully immigrating to those countries. They may have fewer international students studying at university. Their exports can have tariffs placed on them by EU nations. They may get fewer tourists as EU tourists will have to get tourist visas. ",
"2mil+ bits live outside the UK. The majority of them in the EU (about 800,000 in Spain alone). Leaving the EU would put in question these people's residency status and their rights. In Spain alone it could lead to hundreds of thousands relocating back to the UK meaning a huge knock on effect to housing, social services, health care etc.\n\nI don't fear for free trade, I think that will remain as part of any exit strategy.\n\nPros more control over laws and borders but I am not one of those who think borders should be closed.",
"A pro many forget about is pleasing UK's own population. Current polls have a slim majority (51-55%) of the population wanting Britain to be more isolationist, focusing on the problems within it's own borders over fixing Greece for example. Some also think it will help Britain's illegal (and legal) immigration problems. Right or wrong, my English wife's entire family and all her friends think the relationship with the EU is unfair, with England giving more than getting in return.",
"One of the potentially big cons of leaving the EU is that the UK would no longer be under protection of EU laws and regulations, such as the European Convention on Human Rights, Working Time Directive, Antitrust laws and so many others which protect UK citizens from not only from companies but from the UK government.\n\nWhile I would somewhat agree that this could be seen as a pro, as the UK would have more control over its own country, when you have a government that is trying to enact laws such as the D(r)aft Communications Data Bill, it is nice to have someone who seems to only actively work FOR the people rather than against.",
"This is a very complicated subject and a discussion that does this topic any justice is not very ELI5. However I'll add some comments on why the UK may want to leave but not all of them will be fully justified as it includes the general public's perception on matters. \n\n\nThe EU is undemocratic. All laws are proposed and written by the unelected European Commission. The EU wouldn't meet its own criteria for joining the EU.\n\nThe public were led into it under false pretences as a common market. The EU today is very different to what was voted on in 1975. \n\nThe EU has expanded too fast and there are proposal to expand further and have borders with Syria and Russia. \n\nThe median wage of, particularly eastern, countries is much lower then the UK. The population of these countries are heading to the UK to work and a fair rate. Many see net immigration into the UK as too high. The reality is probably more like services (school places, healthcare, housing) are not keeping up with demand for workers.\n\nThe migration crisis encouraged by Angela Merkel has greatly concerned the UK. It is seen that providing aid to the camps surround Syria is the better option (money goes much further and the government are donating very generously compared to other nations). The actions (raping, murdering and general anti social behaviour) by some of these migrants have only reinforced this view.\n\nIt is seen that the UK doesn't have much say in how the EU is run and the political opinions on matters may differ with many other nations. (It would be interesting to see how the UK is viewed in the EU, I suspect they are seen as the bad boy who rubs against the grain).\n\nWith the price of oil, it would be foolish for Scotland to call another referendum on a leave vote. Wales is much more heavily 'subsidised' by the rest of the UK. The population isn't as for the EU as their politicians say they are (although may just clinch a stay vote). And then there is the complicated subject of northern Ireland... \n\nThe UK pays just under £20Bn to the EU and only £10Bn is invested back into the UK. When the government are actively trying to save money, a £10Bn net saving by leaving is compelling, especially when the health service is desperate for more funding. \n\nIMO, the real question is what will happen upon a leave vote. Would the EU use the carrot or stick to try and get the UK to stay? Would the UK want to be a member of a club that uses threats to keep countries in line? German cars are very popular with the public and there is a large trade deficit with Germany and France to aid the negotiations for free trade with services without free movement, however this very much goes against the EU's idealogical views.\n\nThe US seems to like butting in on this, but if they tried to have a political union and free movement with south America it wouldn't be very popular with their population. \n\n\n \nEdit to add some more:\n\nThe EU has contributed to the decline of the the fishing industry with the exclusive waters the UK once enjoyed now being shared with other EU countries. \n\nThe lack of being able to set trade tariffs have lead to the loss of 2 steel manufacturing plants recently. The energy prices may have ultimately lead to their demise but the UK could have at least prolonged their death to see if there was any light at the end of the tunnel.\n\nThe question the EU members need to be asking is, do you want to be a a state or a country? The UK views itself as a country but the path the EU is on will ultimately lead to a United States of Europe. \n\nI liked this quote:\n\"\nFor a stable political entity, cultural convergence should precede political convergence. See the USA, GB, Germany for successful examples.\nExamples of what happens when you do it the other way around include Yugoslavia, the USSR and the EU. \n\"",
"Very hard not to be biased when answering this question. The source that I use is The Economist, which is pro-EU, as I am.\n\n**Pros**\n\nTrade: Avoid exporter tariffs and have access to the single market\n\nEU budget: Britain pays £340 per year per household, but receives £3000 from the EU in other things such as trade\n\nRegulation: Red tape is reduced massively when trading with Europe\n\nInfluence: Britain has influence as a very significant member of the biggest economic community in the world\n\nImmigration: Immigrants provide a not-insignificant amount of growth, they also have, on average, better qualifications than the average British citizens\n\n**Cons**\n\nTrade: Britain can negotiate it's own trade agreements\n\nEU budget: Britain pays £350 million to the EU every week, which could be better spent elsewhere\n\nRegulation: Leaving will give Britain back a lot of controls over certain sectors of law\n\nImmigration: Britain can decide who to let in\n\nInfluence: Britain has very little influence within the EU, leaving will let Britain gain more from institutions such as the Commonwealth.\n\nVery basic, but provides a quick overview"
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acyi7c | how does copper in gloves, socks, or compression sleeves relieve pain? | I keep seeing commercials with Brett Favre or other people talking about copper in socks or other sports related equipment and how it relieves pain or increases circulation. How does this work? Or, possibly a better question, why is it bogus? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/acyi7c/eli5_how_does_copper_in_gloves_socks_or/ | {
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"It doesn’t do anything. \n\nAs for why it’s bogus; that would be because it doesn’t do anything. \n\nFools are easily parted from their money and there’s always someone willing to sell them some bullshit. ",
"Its called the placebo effect.\nMind over matter.\nIf you believe it works often your mind will block mild pain.",
"How does it work? Magic, or something to that effect because in truth it [doesn't work.](_URL_0_)\n\n",
"They are most likely bogus. A [2013 study published in PLOS One](_URL_1_) used a double-blinded placebo study in which 65 participants self reported their outcomes. Their findings showed that there was no significant difference between the four devices and their effectiveness in treating pain: between a copper device and a non-copper device, the difference in pain treatment was indistinguishable.\n\n & #x200B;\n\nA [1983 study published in Life Sciences](_URL_0_) demonstrated that an oral dose of Copper Salicylate reduces pain in rats with arthritis. However, there is little evidence that copper, impregnated in cloth or fiber materials and worn, can reduce pain more effectively than other compression wears.",
"It is a placebo effect. The mind is a very powerful thing and if you think something will help you a lot of the times it will just from your belief. The placebo effect even seems to work when people know that it is a placebo though it will be less effective. ",
"Celtic folk belief. Copper bracelets and ankle cuffs for what we now call arthritis. Remade for the 21st C.",
"They don't. The compression is what actually helps.\n\nThe copper however DOES have anti microbial properties, which for a compression item which can cause sweating can be helpful.\n\nI have some copper wrist compression for carpal tunnel, and I have a pillow with some copper in the fabric to help keep my face from breaking out as often.\n\nIt is just as effective to actually wash your items, from what I've read before the copper anti microbial properties go out the window anytime moisture is introduced. "
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3k969k | white male privilege | So I'm a university student and recently I took a short 5-week summer course. In this course, one of the topics we went over briefly was "White Male Privilege". This consisted of a powerpoint with various slides including income earnings showing white male sitting firmly at the #1 position and racial ethnic minorities' earnings as a percentage of white males. THEN someone asked a question a long the lines of "where are the Asian American males' earnings?". To my surprise the instructor said that they left them off the slide but they're higher than white males. The slide literally had "WHITE MALE PRIVILEGE" as the title, but I mean if you're just going to ignore contradictory evidence I feel like it really weakens the argument. I also remember a while back I didn't understand the whole #BlackLivesMatter debate either until a Redditor [explained it](_URL_0_), so I wanted to see if you could do a better job explaining this whole white male privelege thing. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/3k969k/eli5_white_male_privilege/ | {
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"When controlling for other factors such as age and education, asian americans earnings are far below whites. Asian American immigrants tend to be highly educated compared to the average white American and thus get high paying jobs. ([here](_URL_0_) is a paper loaded with relevant data). The issue on that slide isn't (or at least shouldn't have been) that whites earn more than others, it's that two people who are identical except for the color of their skin tend to get paid differently in the US (with whites tending to earn more). \n",
"Basic statistics don't always show the facts. No, your teacher shouldn't have left off the fact that overall Asian males make more than White males, but should have explained why that it. Generally, Asians are more likely to attain higher levels of education than their white counterparts hence why they generally earn more. In 2004, white males earned $31,335 while Asian males earned $32,419. (Even Asian women earned more on average than white women, though both of them lag behind their male counterparts regardless of race.)\n\nHowever, this does not break it down by education level. When you look at similar levels of education, Asians generally make less than their white counterparts, and the divide gets larger the more education attained.\n\nEducation | Whites | Asians\n-----|-----|----- \nHigh School | 27,311 | 25,258\nSome College | 31,564 | 29,982\nBachelor's | 43,833 | 42,466\nMaster's | 52,318 | 61,452\nDoctorate | 85,658 | 69,653\n\nObviously there are some instances where Asians still earn more such as if they have a Master's degree. Also, this data set includes both male and female workers, so that is also skewing the data as women tend to make less than men on average for both races. ",
"Do you believe in attractive person privilege? Even though they'll still face problems and life won't necessarily fall onto their lap overall it is an advantage to be attractive.\n\nMy accent is seen as the \"smart\" accent in the UK. Until recently you had to have an accent like mine to be taken seriously and even though that isn't true any more it is still a boost. \n\nWell, white privilege is like that.\n\nYou could say that when it comes to dealing with children women are privileged as people are more comfortable with women looking after their children. ",
"There is really nothing to explain here, and the counter that asians make more than white people despite discrimination from white people is a valid one. Same goes for the jewish population, which ranks second in hate crime offenses according to the FBI, but also competes with the white population for income. \n\nWhat social theories like this get wrong is that privilege isn't based on race, it's based on culture, and to an extent you are born into that, but it's also something you can change since a culture is just a set of ideological values. In the Jewish and the Asian community, strong families and education are set in stone. Both are notorious for having parents that push their kids academically, and that value for education shows. Whites used to have this trend, but it's waned somewhat in recent years, causing the average income to drop.\n\nWhat really keeps communities down is the belief that society is against them and they can't succeed no matter how hard they try, and ideas like white privilege do nothing to address that matter, nor do they do anything to address the broken families that exist in the black and latino communities, which are clearly not the fault of white people. If you were to flip it all around and convince white people of these things, you'd see the same problems in reverse.",
"John Scalzi has a great explanation of what white male privilege (or privilege in general) means. [The whole blog post is here](_URL_0_), but I can give you a quick summary: if our society is a video game, then \"Straight White Male\" is the lowest difficulty setting possible. You'll still face challenges because that's life, but NPCs will be friendlier to you, you can open doors that may be locked to people on higher difficulty settings, and you don't have to do as much to complete quests.",
"The keyword to understanding this whole line of thinking is the notion of \"class\". This is the idea that people function as groups based on inherited or innate qualities. In the US, there are three class systems: a race based class system in which whites oppress blacks, hispanics, and indigenous people; a sex-based class system in which men oppress women; and an economic-based class system in which the rich oppress the poor.\n\nWhen a person is born and has a penis, that person is raised by his parents and by society a certain way. He is given certain kinds of toys to play with. Toy guns, for example, toy cars, toy soldiers, legos, etc. He is encouraged to play outside in the woods, to \"explore\", to play games like \"cops and robbers\", \"cowboys and indians\", built forts, etc. He might join Little League or Boy Scouts.\n\nWhen a person is born with a vagina, that person is raised a different way. She is given Barbie dolls, baby dolls, doll houses, Easy Bake Oven, ponies, fairies, princesses, etc. and is encouraged to play games like \"dress up\", \"house\", have tea parties, help her mother put on makeup and comb her hair and get involved in activities like ballet and cheerleading.\n\nThese are called socialization. They're seen as unjust because one is socialized into these roles based exclusively on the anatomy they were born with. The other reason they're seen as unjust is because these are not equal. They're not equal because the means by which girls and boys are socialized are not value-neutral. If you look at the toys boys are encouraged to play with, you'll notice that they represent certain values. Domination, exploration, assertiveness, aggressiveness, confidence, invasiveness. If you look at girls' toys, they also have certain imbedded values that are the opposite of the boys' toys. Submissiveness, introversion, dependency, hospitality.\n\nWhen girls and boys get older, the socialization continues. Womanhood consists of what women must DO. When a woman is turned on sexually, her lips become plump and red, her breasts and butt become firm, her cheeks blush. So when women wear red lipstick that makes their lips look more plump and red than normal, wear bras that push their breasts together and up, making them look bigger and firmer, and wear high heels that make her butt perky, and wears blush to make her cheeks look flush, she is going about constantly looking as though she is ready for sex. Furthermore, she may be wearing a skirt or dress, which again, is not value-neutral. A skirt or dress is easier for men to access her sexually, and is also a symbol of motherhood and pregnancy. If a woman refuses to wear makeup, shave her body, wear stylized or long hair, jewelry, skirts and dresses, high heels, a bra, and instead decided to have the kind of hygiene men get away with daily, she is called a \"dyke\" or said to be trying to be a man, or she may even loose her job. The fact that you as a man don't face spending hours per week and thousands of dollars per year on cosmetics, shaving, hair and nail care, clothing, and have to experience the discomfort of bras and heels and skimpy clothes is part of what it means to be privileged as a man. The fact that you were expected to grow up to take up space, explore, have self confidence, compete and dominate, etc is another example of your privilege as a man. And you don't experience these privileges because you yourself earned them, but simply because that's how you were socialized to behave from birth.\n\nWhen a child is born black, there are also certain expectations. These too are not value-neutral. They are enforced by schools that receive less funding than predominantly white schools. Constant attempts to disenfranchise black voters by not providing voting precincts in black neighborhoods and by gerrymandering. If a black youth falls into drug addiction, the drugs that are more common in black communities carry much harsher penalties than drugs in white communities under the War on Drugs. A black youth is more likely to be stopped by police, frisked, arrested, injured, or killed even in neighborhoods that are predominantly white and affluent. Black unemployment is higher because of discrimination. Housing is harder to come by because of housing discrimination. Loan officers are less likely to give blacks a loan for a business, car, or home (unless of course it's a predatory loan, then black people are more likely to get those than whites). And the list just goes on and on. And remember, all this simply because they were born in the wrong skin and no other reason. So white people who don't have to experience this a systematic, institutionalized class condition are privileged by those who do have to experience it as a class condition.\n\nWhen a person has been socialized as a black woman, all these problems are compounded. The unique experience of black women or latino women or Native American women is an intersection of their oppressed class status as both persons of color and women. The outcome is that these demographics are the most disenfranchised of anyone.\n\nThe reason Asians aren't being considered by your instructor is because Asians don't constitute a class. Asians in the US aren't systematically and institutionally oppressed by any other group. They may be stereotyped, for example, as \"bad drivers\" or \"good at math\", or people who eat cats and dogs, but these stereotypes don't result in higher rates of poverty, incarceration, addiction, etc. And Asians don't earn more on average than other groups because of reasons pertaining to class, but for reasons having to do with their own culture. So an Asian parent may socialize their child to be a good student, and maybe even to excel at math, but he isn't doing this as part of a perpetuation of class oppression of some other group. Of course, an Asian who has good parents who send him to a good school is privileged over another child white or black who didn't have such an advantage. But this is not a class privilege, just an individual one that is not dependent on class stereotypes and oppression."
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8bm01a | how do most radio stations get music artists to say what station they are being played on? | ex: This is Justin Timberlake and you are listening to B96 | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/8bm01a/eli5_how_do_most_radio_stations_get_music_artists/ | {
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"Artists record those promos for the station. Usually they do a whole bunch at once and just send out the tapes. It helps both artists and stations promote themselves, so it's a win-win.",
"Their agent gets an offer that says “get Celebrity X” to do these 20 promos for $2,000. Celebrity says ok, makes a recording, gets paid, and there you go. \n\n*prices have been entirely made up. I don’t know the market for these promos."
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5upmht | what is the mathematical constant, "i?" and, what is the importance of it? | Before you start typing away, I am well aware that the constant "i" is in fact √(-1). What I am really asking is, what IS it? Unlike a constant like 1, I can't really think of what √(-1) IS. I can imagine 1 apple, but √(-1) apples doesn't really come to mind.
I mainly came to ask that question when I began to research more into the Mandelbrot set. Of course, I only understood bits and pieces as am I still only a AP Calculus BC student (for those of you who are non-American, Calculus BC is Calc I, and Calc II. You cover derivatives, limits, integrals, some (basic) differential equation stuff, and sequences & series). To my knowledge the set has to do with complex numbers, which is why I went to ask this question.
As for my other question, what are some of the applications of "i?" While your at it, if there are any proofs that prove something we already knew using "i," I wouldn't mind seeing/hearing about it. Although, that might still be over my head...
Lastly, if you have any suggestions for books on this topic that wouldn't be way over me then I'd love to read it. Whether it's about the Mandelbrot set, "i" or anything else related to math.
Thanks!
| explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/5upmht/eli5_what_is_the_mathematical_constant_i_and_what/ | {
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"Complex numbers can be written using two notations. Polar which is a magnitude and an angle, and rectangular. Rectangular gives the magnitude along the real axis and separately the magnitude along the imaginary (i) axis. \n\nIf you took both notations together, you'd see that the magnitude and angle in polar form exactly matches the hypotenuse formed by the magnitudes from the real and imaginary axes in rectangular form.\n\nIf you are still confused, I'd suggest researching more on complex numbers. They are a very useful mathematical construct especially if you plan on studying any form of engineering. \n\n ",
"There's a reasonably simple way to get intuition about what exactly 'i' is. Let's say you have 2d space, so you have the origin, 0, and you have an x-axis and a y-axis. You can label points by calling them (*a*, *b*), which means go *a* units along the x-axis, and *b* units along the y-axis. But let's call the x-axis the real axis, and the y-axis the imaginary axis. And instead of calling a point (*a*, *b*), let's call it *a* + *b*i. There's no reason why we can't do this, all we're doing is changing names. We call these numbers the complex numbers, and they have the property that when you multiply *a* + *b*i by i, you rotate that point by pi/2 radians(90 degrees) anticlockwise. That's essentially all we want, and really, that is exactly what i does, and that's exactly what makes it useful. That's what the number i is, it rotates the plane 90 degrees anticlockwise, just like how multiplying by -1 rotates the plane by pi radians (180 degrees) anticlockwise, and multiplication by 1 rotates the plane by 0 radians (0 degrees) (or 2pi radians, or 4pi radians, etc). Complex numbers allow us to look at this 2d plane, and give us the freedom to rotate it and scale it however we want in a way that's much simpler to write down than matrices.\n\nIf you've met matrices before, then it is fairly easy to get an idea of what i is (and complex numbers in general) by looking at certain 2x2 matrices. The equivalent of the complex numbers in matrices work exactly the same way as normal complex numbers. When you multiply them, they rotate the plane by some angle, and scale a vector by some amount.\n\nAs for the uses, there are many, and since I'm not familiar with the US education system, I'm not sure which examples are best to give, but I'll try to give one or two.\n\nMaybe you are familiar with the trigonometric functions, sin and cos. Maybe you've also been asked tedious questions like \"show that cos(10x) = blah blah blah\". If you just go at this problem directly, I'd imagine that you'd go about using double angle formulae and the like, and slowly working your way towards the answer. Complex numbers make this all so much easier, because you have the result that e^(ix) = cos(x) + i sin(x), where x is a real number. So if you're asked to find, for example, cos(10x), you know that e^(10ix) = cos(10x) + i sin(10x), so cos(10x) is the *real part* of e^(10x). You also know that e^(10x) = (e^(x))^(10) = ( cos(x) + i sin(x) )^(10), and you can easily find this using the binomial theorem, and you know that the real part of this (the part that isn't multiplied by i) is equal to cos(10x). Complex numbers make all sorts of tedious trigonometric calculations incredibly easy.\n\nAnother example is in linear differential equations. I'm much less sure that you'd have seen this (but maybe?), but I'd be happy to try to explain how complex numbers make this easier if you're interested.",
" > What I am really asking is, what IS it? \n\nThis is why it's sometimes called an imaginary number, there isn't anything concrete that one can think of that is *i*. It is a relatively abstract concept. The more you go into maths the more is becomes less tied to the natural numbers (1,2,3...). We've abstracted it to make it easier to manipulate. The easiest example I can give of this abstraction is multiplication. That's an abstraction of addition multiple times. Instead of doing 5+5+5+5+5=25 it's quicker and easier to create something else (multiplication). Now we don't even think of addition when we multiply, we think in terms of multiplication. \n\nTo get back to *i* and whole numbers. First we have whole numbers (1,2,3,..) then we extend that to positive and negative. Then we can extend that further to the fractions in between. After that we can do irrational numbers like pi (that cannot be expressed as a fraction). This is the real number line. Can we extend the set of numbers even more? Yes we can! The next extension is called the complex numbers. What this does is extend the real numbers from a single line into 2d space. The way to make this work we express these numbers in two parts like in a normal cartesian plane. E.g. 2+3*i*. This is where the *i* comes in. The way to make it work is by using *i*. \n\n > As for my other question, what are some of the applications of \"i?\"\n\nElectronics, electrics, computing, anything to do with spacial things (e.g., aeroplanes, radars, communications), engineering etc. It's a *very* useful concept. \n\n > if there are any proofs that prove something we already knew using \"i,\" I wouldn't mind seeing/hearing about it. Although, that might still be over my head...\n\nMy favourite is [Euler's identity](_URL_0_). If you've covered *i*, trig and radians you could youtube a proof of this. \n\n > Whether it's about the Mandelbrot set, \"i\" or anything else related to math.\n\nJust on the Mandelbrot set, even though it uses *i*, it's not actually too important. The important thing about the Mandelbrot set is as an introduction to chaotic systems, fractals and recursion. If you look up fractals that should yield something. It doesn't require much background to understand it really. ",
"Sinusoids can be written as exponential functions using Euler's formula:\n\n e^(*ix*) = sin *x*+ *i* cos *x*\n\nThis makes for convenient arithmetic. Multiplying two exponential functions is just a matter of adding exponents, but multiplying sinusoids involves remembering messy trig identities.\n\nSo in any field that deals with waves, whether it's electrical signals, earthquake vibrations, radio, etc. , this bizarre and hard-to-grasp concept ironically simplifies the math and saves a lot of time and effort."
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1nfvh1 | how would einstein "work" on his ideas? how did he go from an idea to an equation? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1nfvh1/eli5_how_would_einstein_work_on_his_ideas_how_did/ | {
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"A common way to work on an idea that's all math is to just mess about with established equations and/or axioms and see if you can't get it where you want it. \n\nIIRC there was an instance - although this one was serendipity - where Einstein made an equation in which one component was an energy value, but he noticed this equation in its entirely mirrored exactly an equation in which the same component signified the mass and this put him on the E=mc^2 idea.\n\nIf I want to try and unite electromagnetism, gravity and the nuclear forces into a single united force, for example, I'd write out known equations for all of them and try to find a way to play with each to get them into the form of an equation from the other, or if I think that XYZ from one force and ABC from another are related I can play with the equations hoping to make one equation with both XYZ and ABC in it to work out their relationship.",
"So, this is one of those things that doesn't get said a lot, but is really key to the whole affair: mathematics is a language and most equations are just phrases in a sentence.\n\nWhen people are coming up with a new equation, they're really just thinking up a new idea, and writing it down in the language of mathematics, because they feel that's what would express it most concisely or accurately.\n\n\"Going from an idea to an equation\" is the same as \"going from an idea to an English sentence\"; you just write it down, and if it doesn't look quite right, you fiddle with it until it says *juuuust* what you want it to.",
"On some level these are the same thing, and you learn to read the ideas that equations represent. In that sense this is like asking how you go from ideas to sentences that other people can read. Not that it's nearly that easy, I'm just saying that to set the stage. For example:\n\nMechanical motion can be converted into heat. How much heat is in mechanical motion? The two things under consideration are\n\n1. the object\n2. how it's moving.\n\nthe particular object in question probably shouldn't matter; this is really about *how much* object we have. So we'll assume that the energy of motion is a function of mass, m and velocity, v. This turns out to be right; but beforehand this is just a 'reasonable' guess. Sometimes this is the best way to go.\n\nImagine smacking a clay ball into a wall. A certain amount of heat is generated at the wall. Smacking 2 balls side by side would make twice as much, 3 balls 3 times as much, etc: the energy is linear in the mass.\n\nThe next part is somewhat sophisticated:\n\nImagine hitting two clay balls together by throwing them at each other, with the same speed. They hit and have no motion energy at the end, releasing all of it as heat. so the energy lost was that of 2 masses moving at velocity v. Now switch perspectives, so one ball appears still, another ball smacks into it twice as fast and you then have two balls stuck together moving at speed v. The energy lost to heat is the energy of a mass moving at twice v minus twice the mass moving at v. These are the *same situation* being described from different perspectives, so they need to evaluate to the same answer. So combining the results of both perspectives tells you that twice the velocity has four times the motion energy. Repeating with other/more masses would show you that three times the velocity has nine times the motion energy, etc. So we know that motion energy is quadratic in the velocity.\n\nAll that's undetermined is a potential constant multiplier, which could be determined by experiment (and altered by a choice of units), so we'll stop here.\n\nTo me, the experiments make sense but the \"velocity dependence\" stuff looks messy and awkward. But this whole description is just saying that\n\nE=1/2 mv^2\n\nand when I read the equation, that's what I see. For a physicist, equations are a *language* for precisely capturing physical phenomena.\n\nFor special relativity at least (general needs tough mathematical tools to talk about accurately at all), I can be more direct. We have these requirements:\n\n1. the speed of light is constant to everyone, no matter how they move. Experimental fact.\n2. transformations between inertial frames (i.e. different perspectives at constant velocity) need to respect vector addition. If they didn't, then 0 net force in one frame would become non-zero in another, which contradicts the definition of inertial (a constant velocity does not accelerate).\n3. Switching *back* to a previous frame is given by the negative of the velocity you boosted to in the first place.\n\nThese three postulates imply the Lorentz transformation, which ultimately gives you the underlying geometry of relativity (fleshing this out properly was Minkowski's contribution, not Einstein's). Forcing consistency with classical mechanics mathematically and in various thought experiments gives you most (potentially all?) of the physical rules of relativistic mechanics.\n\nSo the general steps are\n\n1. come up with physical postulates/reasoning/thought experiments\n2. Translate these into equations. This step normally isn't magical, once you're familiar with what the mathematical concepts physically mean. However it can still be very difficult to find and properly use the right mathematical tools for the job.\n3. Use the equations to come up with the overall logical structure/experimental predictions/calculation methods.\n4. Go to step 1 and repeat until you get grant money.\n"
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acg3h0 | why was it so groundbreaking that ancient civilizations discovered/utilized the number 0? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/acg3h0/eli5_why_was_it_so_groundbreaking_that_ancient/ | {
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"the number zero that has the meaning of nothing is important because it is the idea of an absence, or a set of nothing. but the idea that zero can be used as a digit to increase the value of a number is fascinating. \n\ntake roman numerals for example. sure, numbers like nine (IX) are simple to write, but get much higher and it becomes cumbersome and difficult to do mathematics with. a number like 998 is written CMXCVIII. badass but not efficient. using zero as a placeholder digit allows larger numbers to be created and written easily. we know the amount based on the succession of zeros. this is the arabic system of writing numbers\n\none mathematician that used this idea to propel mathematics is al-khwarizmi. the latinization of his name is al-jabr, which is where the words algebra and algorithm come from. his book \"the compendious book on calculation by completion and balancing\" is the text that founded this way of mathematics. by using simple variables and equations, al-khwarizmi created this branch of math for heritance cases in bagdad in 830 (this was due to specific fractions of money going to husbands, wives, brothers, and other family)\n\nit took a while before his work reached europe due in part by the crusades and the focus on geometry and greek mathematics at the time. by around 1200, trade began opening up, and european mathematicians adopted the arabic number system that we use today\n\nsoon, fibonacci's text \"liber abaci\" or \"book on calculation\" was dropped, expanding upon the ideas of balancing equations and solving them. from there most of higher mathematics like calculus was born\n\nedit: lol this is what i get for writing this high at 4 am but thank you for the clarifications/corrections",
"To go a bit against the others here:\n\nThe fact that people discovered, that \"nothing\" can be expressed as a number - that you can also calculate with - is not obvious and very revolutionary.\n\nIt shows a new level of abstract thinking that actually leads to mathematics as something different than just \"counting things\". That a number substracted from itself equals 0 seems painfully obvious to us now, but imagine having to do math without this simple operation.\n\nThe decimal system is nice, but a very similar system is also possible without 0 - the Roman numerals just are exceptionally confusing. There is nothing stopping people from expressing (for example) 2437 as \"2D4C3B7A\" and 3004 as \"3D4A\" and some cultures used systems that were conceptually similar.",
"Using the number zero means you have graduated from using numbers just to count, to doing actual math. \n\nDoing math needs you to use a whole lot of abstract concepts, and the number zero is the most important of these.",
"To put it shortly, it was the first number to be used and mentioned that is completely abstract with no physical representation. ",
"There are a few fundamental pieces you need to do advanced math things.\n\nYou need an abstract concept of natural numbers for bookkeeping, you need negative numbers for finance and credit, you need things like infinities for calculus and so on.\n\nZero is a fundamental piece that basically unifies everything. The same math works counting chickens and calculating circumference of the earth and doing finance and doing physics and doing a lot of the theoretical stuff.\n\nPhysics for example has different rules for small things and for big things. There is no unified set of rules... yet. Math used to be like that until it got a lot more rigorous and we got more proofs that everything is connected and is in essence the same.",
"the idea of a number that isn't material and based in reality shows a transition from \"let's work in things that are REAL\" to \"hey guys, get this, abstract stuff! cool right?\" which is logically quite a leap.\n\n0 has no basis in anything real, there is nothing in the ancient world that is truly \"nothing\" thus, creating and putting such a number to use requires not only thinking in abstract terms, but also working in them. Also big numbers which is growth too. Just my thoughts on it, I'm not a scientist and I kind of pulled this out of my a**.",
"Well there's two questions, one more obvious than the other. Why was it important? And why was it a notable achievement?\n\nThe obvious first, why was it important? 0 is an extremely useful number. In math, it generalizes problems. Instead of saying, what is this solution to x^2 = x + 7, we can now ask, what is the solution to x^2 - x - 7 = 0. You can generalize the left as \"all polynomial equations\", and start thinking more clearly. There are other examples, just think about using it in high school math. The trick where you \"add 0 to the equation\" when completing the square in a quadratic equation. \n\nFor the non-obvious. Why is it notable? I guess my best explanation would be, how do you distinguish between \"different\" zeroes? 0 is nothing. Counter-example: 1 sheep is a single existing sheep, 0 sheep is no sheep, no sheep is just nothing, nothing is the same as 0 oranges. Is 0 oranges the same thing as 0 sheep? Should I even use a number that can't distinguish itself between two objects? Would that even be considered a number? What use would this even have? It's a non-intuitive, abstract thought. ",
"Saying that nothing is something is a big step as far as mathematical/logical thinking goes. Math started as a description of the world (“I have two sticks, you have two sticks, we have four sticks”), so saying that “I have no sticks, you have two sticks, we have two sticks” instead of just “you have two sticks” in a symbolic form is a subtle, yet hugely intelligent, move. \n\nThe other reason is convenience. If you look at something like Roman numerals you can see how quickly numbers get ugly when you can’t just shift everything over. LXXIV is a hell of a lot uglier than 74. You need zero to start expression numbers in sums of powers of tens (or whatever base you use). You can compose numbers in a much easier way. Try doing multiplication or division with Roman numerals. It sucks, and a big reason for that is the lack of zero. Our algorithms are almost entirely dependent on its existence. ",
"One example: in China, Korea, and other east asian countries, babies are considered 1-year old when they're born. On top of that, everyone turns a year older when they pass New Years Day. So at this moment, there are 2-year olds in China who were born less than a week ago.\n\nThat system is legacy from before civilization adopted zero and the mathematics it enables, but it's still being used, no matter how flawed it seems.",
"Math in ancient Greece was geometry, not arithmetic. Numbers came in discreet intervals (1, 2, 3, etc.). What we call rational numbers were dealt with as ratios between line segments. You can't have a line without any length, however.\n\nThe educated view seemed to be that you can say the word \"nothing,\" but nothing is not a thing, and it doesn't make any sense to talk about something that is not a thing as though it were. There is a lot in Plato about the inability to say anything about non-being, for example.\n\nThere are limits to geometry, however. Merchants would have felt these, but their calculating tricks didn't impact rigorous mathematical thought. You can't do all the neat stuff we do with numbers if the only numbers are the natural numbers, though. You need 0 to get integers (and real numbers).\n\nSo allowing 0 to be a number requires that people think about numbers differently. Numbers had to become the thing serious men would try to do math with. Only then was the need for 0 felt.",
"Man, they really should bring these back....\nJust watch [Schoolhouse Rock's \"My Hero Zero\"](_URL_0_)\n\n[Intro: Girl & Narrator]\nZero?\nYeah, zero is a wonderful thing. In fact, Zero is my hero!\nHow can zero be a hero?\nWell, there are all kinds of heroes, you know\nA man can get to be a hero for a famous battle he fought\nOr by studying very hard and becoming a weightless astronaut\nAnd then there are heroes of other sorts, like the heroes we know from watching sports\nBut a hero doesn't have to be a grown up person, you know\nA hero can be a very big dog who comes to your rescue\nOr a very little boy who's smart enough to know what to do\nBut let me tell you about my favorite hero\n\n[Verse 1: Bob Dorough]\nMy hero, Zero, such a funny little hero\nBut 'til you came along, we counted on our fingers and toes\n\n[Refrain 1: Bob Dorough]\nNow, you're here to stay, and nobody really knows\nHow wonderful you are, why we could never reach a star\nWithout you, Zero, my hero, how wonderful you are\n\n**[Bridge 1: Girl & Narrator]\nWhat's so wonderful about a zero? It's nothing, isn't it?\nSure, it represents nothing alone\n\n[Chorus 1: Bob Dorough]\nBut place a zero after one, and you've got yourself a ten\nSee how important that is?\nWhen you run out of digits, you can start all over again\nSee how convenient that is?\nThat's why with only ten digits including zero\nYou can count as high as you could ever go\nForever, towards infinity\nNo one ever gets there, but you could try**\n\n[Verse 2: Bob Dorough & (Girl)]\nWith ten billion zeros, from the cavemen until the heroes\nWho invented you, they counted on their fingers and toes\nAnd maybe some sticks and stones (or rocks and bones)\nAnd their neighbors' toes\n\n[Refrain 2: Bob Dorough]\nYou're here, and nobody really knows\nHow wonderful you are, why we could never reach the star\nWithout you, Zero, my hero, Zero, how wonderful you are\n\n[Chorus 2: Bob Dorough]\nPlace one zero after any number\nAnd you've multiplied that number by ten\nSee how easy that is?\nPlace two zeros after any number\nAnd you've multiplied that number by one hundred\nSee how simple that is?\nPlace three zeros after any number\nAnd you've multiplied that number by one thousand\n\n[Outro: Bob Dorough]\nEt cetera, et cetera, ad infinitum, ad astra, forever and ever\nWith Zero, my hero, how wonderful you are",
"To add to the other comments, which in itself are quite complete, it also works as a blankspace in a way. You can differenciate between '3', '30', '300', ... \nThese Numbers - without the Zero - would all mean the same, but the Zero as a suggestion of 'nothing' is the revolutionary thing. It allows us to group numbers and expand them into infinity with only ten different symbols. \nSorry if that has been said already, in that case i didn't realize it.",
"To us 0 is obvious but that's only because we've been using it for so long. So let's compare to something that's not so intuitive. Take imaginary numbers (I know I should call them complex numbers but \"imaginary\" helps in this case). \n\nFinding a square root means finding a number, that when multiplied by itself, gives you the number you have. example, 2x2=4 but *also* -2x-2 = 4, because multiplying two negatives gives a positive. \n\nSo what would be the square root of -4? You could say \"well there isn't one\", or you could say \"fuck it, let's say that the square root of -1 exists and just call it *i*\", in that case the square root of -4 would be 2i. \n\nNow is the time when people say \"Yeah but that doesn't really exist, you just made up *i* to do math with it\", no it absolutely does exist, the symbol of *i* was made up yes, but *in the same exact way that 0 was made up*. It's just a symbol, it represents a concept, for 0 that concept is \"nothing\" for *i* that concept is \"square root of negative numbers\".\n\nIf you have a hard time accepting that *i* is real, despite us not having \"numbers\" for it, then you should have a reasonable understanding of why \"0\" was revolutionary. Representing nothing is not entirely intuitive.\n\nThis goes for other \"number concepts\" as well. Negative numbers for example, \"you can't have less than nothing\", \"well lets pretend you can and just represent it as a one with a dash in front of it\" then over time the concept became internalized.",
"Just as a side note, I recommend reading the book, \"Zero: The Biography of a Dangerous Idea\". \nVery interesting book that tells about how zero came to be, and how complex it really is [:",
"Way back before the Romans, the Phoenicians did arithmetic sort of like we do. They did not have a zero, but they used a space where we would use a zero in a multi-digit number. Hindus also had digits like the ones we use today and used a space instead of a zero. Additionally (heh heh), abacuses were in widespread use. They also used columns for multi-digit numbers. So, for the use of addition, the zero digit seemed to be just a notational convenience. BUT, the big notion (probably noticed later) is that considering zero as a *number* like the others cleaned up addition as an abstract concept. It also opened the next door of negative integers. Zero opened the door to more abstract arithmetic and algebra which Fibonacci learned from Arabs and wrote a book on it for Europeans. This, in turn allowed trade to flourish and lead to the Renaissance in Europe. So one could consider breaking ground for arithmetic, algebra, the European renaissance, and quantitative science. ",
"From what I hear, it's because ancient math was radically than modern math. First off, there was no \"1\" or \"2\". There was a number of objects like 1 or 2 bricks or people. There were also objects of length 1 or 2 units but a length of 0 just meant nothing was there so why even consider it. Thus, adding 2+7 made no sense because what were you adding? The figures? In that case then the answer is 27. If you were adding 2 apples to 7 apples, then you have 9 apples. If you have a stick of length 2 units and you use it to divide a stick of length 7 units, then you'd have 3 sticks of length 2 units and 1 stick of length 1 unit. Having 0 in either case in this framework makes no sense. There's essentially nothing there.\n\n In fact, in many ancient maths, lengths and basic geometry was the only math. For fun, look up the flag of (I believe) Nepal. This flag is one of the only national flags that isn't a rectangle. If you search long enough, you can find perfect, geometric instructions on how to make one out of practically nothing. Those instructions read exactly like ancient math Greek math did and that was the only math they had.\n\nIntroducing 0 meant they could use it in an abstract mathematical way and had representation for it. 0 was tangible and useable meaning the concept of nothing was tangible and useable. ",
"Because the human brain struggles to understand the concept of “nothing.” \n\nThere is always at least one of a thing. If not, why think about it?\n\nThe fact that someone just thought it up and then *was able to explain it* to the idiots around him is amazing. ",
"_URL_0_\n\nThis is a book thats sums up the answer to that question quite nicely. ",
"Practically speaking the main beneficial effect of zero was in having a base ten calculation system within which is far easier to perform simple arithmetical functions. \n\nThe concept of zero was of it being an arithmetical function (like how we'd think of a decimal point) rather than a number for hundreds of years.",
"The number was discovered through a new understanding of accounting. It's the idea that someone owes nothing in a transaction. Otherwise someone owed the other something, which wasn't logical, hence the need of '0'.",
"It's not, people have realized they had nothing since the dawn of time. Mathmaticians just hate it when you point out they are not as cool as they thought. Also most adults don't need algebra.",
"What date was it discovered?",
"It's the concept of place value. Try doing something like long division without place value! ",
"Not related to question. But some info about zero. When people used to count using stones. They used to place the stones on the ground. They noticed the impression of a stone when it was removed. It is said that the symbol for zero was an abstraction of this.",
"We don't have a \"universal language\", you would think. Many people across the world speak a different langue, but we do. The world has adopted what we know to be Arabic numerals.\n\n1,2,3....7,8,9 and 0.\n\nThe number zero I believe originated in China. But not as a number or a concept of \"nothingness\". It was just used as a place holder for a number to come after. The Chinese number system is complex, but say I gave you x amount of sheep.. And you said I'd return with the equivalent in cows in a swap and you took my sheep, my place holder would be 0 until you'd return with x cows.\n\nThe number itself expressed and written as a \"0\" is believed to be expressed as so, as people would count with stones as touched upon by previous posts.\n\nImagine picking a stone up from the dirt on the ground, you'd see a little circular indent. The Indians grasped with idea of nothing left. Zero. \n\nThe fact that we can use 10 digits and manipulate them to make any number infinitely large (or small) made so much possible. That zero meant over time we could express 10 or 1,000 simply.\n\nThe numbering system that came after discovering 0 made it today's universal language. \n",
"The number 0 appears in the records of three different ancient civilizations: Babylon, Indian, and Mayan. What is unusual is that it appears in all three at roughly the same time (\\~3000BC). This doesn’t necessarily mean these civilizations invented the concepts. It is entirely possible that the Babylonians inherited the concept from the Sumerians, Indians from the Jains, etc. Another possible explanation is they were all taught by the Phoenicians at a similar time in history. Although we have limited surviving examples of Phoenician writing due to their choice of writing materials, the evidence that they taught their alphabet to the civilizations they interacted with is compelling, such as the ancient greek origin myths that claim they learned writing from the Phoenicians. Even our modern word \"phonetics\" comes from the Phoenicians. We know the Phoenicians were adept ship navigators and avid traders and there is additional evidence that the Phoenicians may have circumnavigated the globe. This would have put them in contact with the most advanced civilizations of the time and possibly explains why we see the concept emerging across the globe at roughly the same time. If it was in fact the Phoenicians who were responsible for spreading the concept around the world, it just begs the question, who taught the Phoenicians? Is it possible there was an ancient civilization that existed prior to these aforementioned cultures? Could there have been a civilization that possessed the knowledge of concepts like zero long before our modern archeological record begins? Could it be that Plato and the ancient Egyptians were not inventing fictional stories but rather relaying historical accounts when they wrote about Atlantis? If there was a relatively advanced civilization that existed during the most recent glacial maxima, and that civilization was destroyed due to rapid sea level rise during the yonder dryas, would they have attempted to preserve what knowledge they possessed? And if so, how? One likelihood would be the attempt to teach these staples of civilization (agriculture, pottery, writing, etc.) to surviving hunter gatherer populations in an attempt to rebuild civilization. The origin myths of many ancient peoples around the world point to just this. They talk of knowledge bringers, foreigners who appeared and taught their ancestors the necessary building blocks of civilizations. Could this also explain the similarities between the Mayan and Phoenician languages? The same ancient legends all tell of their ancestors surviving a deluge, with some even pointing us to the date roughly 11,000 years ago, coinciding with the younger dryas, or the end of the last ice age, when ocean levels rose by over 300 feet during the period of only a few hundred years. It is entirely possible that a few individuals survived in boats and rafts, and attempted to pass on their knowledge to the primitive people living near where they landed. Is it possible that the most groundbreaking aspect to the origin of the number 0 is that its true origin might be far older than we think?"
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7smgta | how do electrons in an electrical current actually travel? do they jump from atom to atom? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/7smgta/eli5_how_do_electrons_in_an_electrical_current/ | {
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"No. One of the special features of conducting metals is that their outermost electrons are basically shared between all of the atoms. So they act as if they were free electrons bouncing around all over the place. When there is a current they bounce more in one direction than they do in the others, and so there is a net motion of charge (a current).\n\nOne other thing to note. Just as free electrons can easily carry current, they also easily carry heat. So metals are good conductors of heat as well as electricity. That's why touching a hot stove is so painful - the heat flows really fast.",
"The flow of electrons is much slower than the flow of current. Electrons generally move at far less than 1mm/second, while **current** generally moves at 50-99% of the speed of light in vacuum. The way to think about it is like a tube full of marbles. When you push new ones in the end, a different one pops out the other end. It takes a long time for a new marble to make its way through. In 50/60 hertz AC, the electrons just move back and forth slightly. ",
"Say you and a whole bunch of other people are standing neck & neck in a tight corridor, with a door in both ends. The initiere corridor is filled with people. All these people are the electrons in the metal. All of a sudden Steve comes pushing in from the back. This causes everyone to tilt and shuffle forward. Patrick, standing in the other end, ends up being pushed out of the door he is standing by.\nAll the movement due to the push, is the energy moving. ",
"When individual metal (say, copper) atoms join together with other copper atoms, the outer electrons start orbiting ALL the atoms instead of just one of the atoms. This is sometimes called a \"sea\" of electrons. \n\nThe outer electrons in metal are constantly \"jumping\" from atom to atom, whether there is a current or not. Even though they are constantly moving, when there is no voltage applied to the metal the aggregate movement of the electrons is zero. In other words, when there is no voltage applied, the jumping from atom to atom is in random directions such that the average movement of the electrons zero.\n\nWhen a voltage is applied, it causes the electrons to be slightly \"biased\" and the average movement of all the electrons is to start flowing in a certain direction (the average is no longer zero). "
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3sobom | do publicly traded companies place greater focus on short-term results than long-term? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/3sobom/eli5do_publicly_traded_companies_place_greater/ | {
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"Someone else will likely have a more thorough explanation but it all comes down to shareholder pressure. A better run company will not sacrifice future profit for a quick short term gain but under shareholder pressure they may have to make those decisions. \n\nLarger companies under more public (press) scrutiny will likely not take as big of a hit if the investments they're making look to be good investments. If smaller companies take on an expense that harms profit it will lower shareholder expectation if they haven't established a good deal of trust. \n\nPrivately run companies don't have to establish trust with the shareholders as \"the public\" is not set to lose money if they fail. Publicly held companies have to answer to the shareholders and are legally obligated to maintain profits for them. It comes down to whether or not the shareholders trust the company. High trust = the company can make longer term investments that don't pay off right away. Investors are willing to take the risk. Low trust = short term profits. Any risk is a bad one. Keep that stock up!"
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1s8w21 | how can a coax cable carry a hd signal from the wall to my cable box, but i need hdmi or component to get the hd signal from the box to my tv? | If coax is apparently CAPABLE of carrying a 720p signal and 5.1 audio (if I'm using an antenna) why do I need HDMI or component for my ps3 and xbox? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1s8w21/how_can_a_coax_cable_carry_a_hd_signal_from_the/ | {
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"Cable uses compression, and so far there is no standard for compression between the box and display, at least the content owners will allow, for fear of content piracy.\n\nConsoles and such do not have hardware to compress video, so need a direct connection."
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25npmq | why is my sight full of extremely small and multi-colored dots? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/25npmq/eli5_why_is_my_sight_full_of_extremely_small_and/ | {
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"text": [
"[Visual Snow](_URL_0_) or Mardi Gras."
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6hk13v | how do games like overwatch and battlefield 1 (and others) allow you to play the games while still downloading? | I presume they install the core data and files first and then download the cosmetics and graphics related files towards the end, but how does my game handle the new files when it is already running? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/6hk13v/eli5_how_do_games_like_overwatch_and_battlefield/ | {
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"You decide to order a boardgame online. \nYou get your friends together every week to play. \nThe package arrives, you find out that the the fancy game pieces are being shipped separately because they were heavy. \nHowever your friends are still there, you find that the box you just received contains the game rules, the game board and some passable cardboard game pieces. \nSo you can still play with your friends.\nOver the next few days more fancy game pieces arrive, when they come, you swap out the cardboard pieces for the fancy pieces. \nThat's how the download works. The biggest parts of a game are stuff like textures, sound files and videos. But you don't really need them to play, they just make it look nicer. The rules and the code for communicating online are relatively small. So they get sent first. \n \nAlso BF1's single player was split up. Sort of like ordering all 6 seasons of a TV show, and Starting once season 1 arrives. You're watching season 1 while you wait for season 2 to arrive.\n"
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3s2t9n | if blood flow helps heal wounds, why is it recommended to elevate the limb where the injury occurred? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/3s2t9n/eli5_if_blood_flow_helps_heal_wounds_why_is_it/ | {
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"For cuts, if the blood is flowing too fast, it won't clot as easily. Pooling blood clots better, so you raise the limb to slow the flow of blood to the injury. This allows the blood that's already there to clot more easily and stop the bleeding.\n\nFor other injuries, elevating the injury can help limit pain, swelling, and inflammation, which allows blood to flow more easily.",
"EMT and former sports medicine trainer here. Blood flow is important for healing and survival, but swelling is bad. It really depends on the type of injury.\n\nYou elevate an open wound (like a large cut) to help control bleeding.\n\nYou elevate a closed injury (like a break or sprain) to help control swelling, which can restrict blood flow in and out of damaged tissues. Severe enough swelling in an extremity can actually cause something called \"compartment syndrome\".\n\nWhen I was a kid, I broke my arm and had to walk around for weeks with it in a cast, held above my head. I thought I looked like an idiot, but I guess it helped."
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5cdvyg | why does faxing from a smartphone seem to require a third party to do the conversion and transmission? you're using a phone; why can't the conversion be done on your device and the audio fax signals be sent directly to another fax machine. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/5cdvyg/eli5_why_does_faxing_from_a_smartphone_seem_to/ | {
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"This is because cell phone networks compress the audio so that it can more easily travel over the airwaves. Think of it like MP3 files. They filter out certain frequencies and change other aspects of the sound wave to make it take up less space. Unfortunately, fax machines (and dial up modems) work on the basis of sound waves traveling over the phone lines. If you alter the sound wave, the computer on the other end is unable to recognize the sound waves and the transmission gets broken.",
"It's mainly because the mobile voice protocols send your speech data in little packets, and allow for some of these packets to be lost, because having tiny gaps in the sound is more acceptable than a long delay (which you'd get if you insisted on resending lost packets).\n\nThe Fax protocol, on the other hand, is designed to deal with noisy lines, but not with gaps.\n\nTherefore, if you try to use Fax via mobile (or Voice over IP) connections, you'll just get errors pretty quickly, as soon as the Fax protocol notices that there's data missing.\n\nIn order to fix this problem, a special \"Fax over IP\" protocol called [T.38](_URL_0_) has been developed. If the target fax machine understands that protocol and you have an app that speaks it, you can send a fax from your smartphone directly as data rather than audio."
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3j2gqk | what is the evolutionary benefit of certain plants such as tobacco or marijuana containing chemicals that can affect the animal mind? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/3j2gqk/eli5what_is_the_evolutionary_benefit_of_certain/ | {
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"There's a theory that these evolved as pesticides. Something that would destroy the mind of a bug, but turns out to have lesser effects on a human. ",
"Nicotine at least is a fairly potent insecticide. The fact that it also gives people a bit of a buzz is just a happy accident.",
"The active chemicals in marijuana are called cannabinoids. Here's some of what we know so far:\n\n > It has been known for some time that CBG and CBC\nare mildly antifungal, as are THC and\nCBD against a cannabis pathogen. More\npertinent, however, is the mechanical stickiness of the\ntrichomes, capable of trapping insects with all six legs. \n\n\n > THCA and CBGA have also proven\nto be insecticidal in their own right. \n\n & nbsp; \n\n[Source](_URL_0_)",
"I don't mean to suggest that such interactions don't take place all the time (on an evolutionary scale) among various species, but it's worth considering that most evolutionary events took place without considering humanity. \n\nThat is, the observations that\n1. A chemical makes people a feel a certain way\n2. A plant makes this chemical\n\ndo not provide sufficient cause to assume that any relationship exists between human genetic development and the genetic development of that plant.\n\n(Sorry. I know that wasn't very ELI5. In a hurry. Hope it helps.)\n\nEdit: see /u/mugenhunt's answer for discussion of how the plant might benefit from producing the chemical due to interactions with other species. In this case, our nicotine response would appear to be coincidental (at least given this limited amount of information.)"
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8hqsca | how do vines support themselves when they are not "wrapped" around a rigid structure? | For example, [these small brown disks](_URL_0_) seem to be supporting this vine along the underside of a section of roofing. How does this support work? Are there other types of support mechanisms for vines which do not require "wrap" around other structures? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/8hqsca/eli5_how_do_vines_support_themselves_when_they/ | {
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"Those little squiggly things with round things at the ends are like suction cups. They grab onto the surface and infiltrate into microscopic grooves and cracks and that's how they adhere."
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"https://imgur.com/a/0DrhqPu"
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kiqr6 | how a spray bottle works. | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/kiqr6/eli5_how_a_spray_bottle_works/ | {
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"As the trigger is pulled, air is pumped into the chamber with the liquid. Once the pressure is increased, the liquid is displaced by the gas (air) and spurts out of the nozzle of the sprayer.",
"Get a mouthful of water and then spray it out by buzzing your lips. It comes out in a spray because your lips only let a little water through at a time and pushes on it really hard. A spray bottle pushes more water through at time, but uses the pressure from your hand to pressure the tiny little bit of air in the nozzle a whole bunch to make the water spray, and makes the water come out between two circles, kind of like your lips.",
"When you turn your water faucet on, it comes out normally. But if you put your thumb covering the faucet, it tries to push the same amount of water through a smaller hole. When that happens, pressure builds up, because the same amount of water is trying to go through a smaller opening, and when pressurized water goes through an opening like that, it doesn't flow, it spurts. A spray bottle spurts water like that, but the little hole is especially made to come out in a cone shape.",
"As the trigger is pulled, air is pumped into the chamber with the liquid. Once the pressure is increased, the liquid is displaced by the gas (air) and spurts out of the nozzle of the sprayer.",
"Get a mouthful of water and then spray it out by buzzing your lips. It comes out in a spray because your lips only let a little water through at a time and pushes on it really hard. A spray bottle pushes more water through at time, but uses the pressure from your hand to pressure the tiny little bit of air in the nozzle a whole bunch to make the water spray, and makes the water come out between two circles, kind of like your lips.",
"When you turn your water faucet on, it comes out normally. But if you put your thumb covering the faucet, it tries to push the same amount of water through a smaller hole. When that happens, pressure builds up, because the same amount of water is trying to go through a smaller opening, and when pressurized water goes through an opening like that, it doesn't flow, it spurts. A spray bottle spurts water like that, but the little hole is especially made to come out in a cone shape."
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3o1y3r | what would happen if global warming was reversed, and the earth was dropping in temperature? | Would it be better or worse for the Earth? What effects would it have? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/3o1y3r/eli5what_would_happen_if_global_warming_was/ | {
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"They are called Ice Ages. It happens every 20K years or so. It's no big deal, unless your buildings get crushed by glaciers. Sorry Norway.",
"Uh, what is the opposite of hot?\n\nGo watch the kids movie Ice Age... There's your ELI5",
"It depends on how cold things got. Once upon a time, all life on Earth was almost wiped out by runaway cooling.\n\nYou see, if something started removing all of the greenhouse gasses, cooling the planet, more and more ice would form. Ice is reflective, so less and less of the sun's energy would be absorbed by Earth as more and more of it is reflected back out into space, causing further cooling. Earth gets colder and colder until it gets so cold that gasses from the atmosphere start to precipitate out, making things even colder until Earth becomes a permanent ice ball (at least until a high energy impact re-melts everything).\n\nWhat they think happened in the past was a new type of algae organism developed that converted CO2 (a greenhouse gas) to oxygen and when it died, it sank to the bottom of the ocean, trapping the carbon. Eventually, enough CO2 was replaced with oxygen that the Earth started cooling and the oceans froze. After the oceans froze, almost all of the algae died and enough volcanic activity occurred to replenish the CO2 levels and start thawing. In the millennia that followed, the algae was at it again, but animals evolved quickly enough that converted oxygen back into CO2 (and produced methane), maintaining a more balanced greenhouse gas level in the atmosphere."
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58z0hc | are all the stars we see in our night sky part of milky way, or some belong to other galaxies too? also, how do we know if a star is from other galaxy? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/58z0hc/eli5_are_all_the_stars_we_see_in_our_night_sky/ | {
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"Yes, all the stars we can see with our eyes are inside our own galaxy. Think of our galaxy like our own bubble. We can see another galaxy bubble, Andromeda, but it's so far away it just looks like a fuzzy in the night sky. I don't think there are any other galaxies we can see without a telescope.",
"All the stars you see at night are part of the Milky Way. Most are \"close\" as far as stars go.\n\nThe nearest major galaxy is 2,500,000 light years away, you'd never see an individual star at that distance without an incredibly powerful telescope.\n\nIt's possible for a star to originate in one galaxy and get ejected in the direction of another, but we've never found one nearby that's carrying that much speed.",
"Scientists have determined that stars ought to have 'fingerprints' - a specific set of colours (wavelengths) composing the light which is radiating by stars.\nAnd if we take a fingerprint of a certain star we could see that the pattern matches to the one we know but shifted. And on the basis of the shift it is possible to determine the range between the Earth and the stars and map them. And taking this into account we can group stars in clusters, galaxies, etc.\nSo, you can possibly tell if the star is from the Milky Way or a different galaxy.\nAdditionally, the light intensity from a star drops really fast with the distance (if the distance increases two times the intensity drops 4 times) so you need quite an aperture to collect the needed amount of light to see a distant star.",
"As others have responded, you can't see **individual** stars in other galaxies with the **naked eye**, but you can see **galaxies** of stars. In the Northern Hemisphere, you can see [M31/Andromeda](_URL_0_) and from the Southern Hemisphere, you can see the [Magellanic Clouds](_URL_1_).\n\nOf course, with **telescopes** we can see all sorts of structures in the universe - including stars from other galaxies.\n\nedit: added \"in other galaxies\"",
"I don't see anyone answering the question of how we determine if a given point of light in the sky is local or is another galaxy, and aside from pointing a telescope at it to get a better look, there's a technique called parallax. Basically you take a picture of the night sky when the Earth is on one side of its orbit, then another pointed in the same direction when the Earth is exactly opposite in its orbit. Objects nearer to us will appear to have moved in the picture more than objects farther away, the amount of movement is inversely proportional to its distance. Similar to how you'll be travelling in a car out in the country and you'll see road signs and whatnot whizzing past but the trees a few hundred yards off the road don't seem to move quite as fast and the mountains several miles away hardly seem to move at all.",
"Not everything you see in the night sky is a star. Depending on where you are in the world because of light pollution, you can see the planets in our solar system, other stars and distant galaxies. Some of the lights on the sky that look like single stars are actually clusters of stars that are so far away they look like a single point of light to us. You will never be able to see a single star from another galaxy rather you will see the whole galaxy as a single point of light because of how far away it is. However if you were able to see the andromeda galaxy in the sky it would look about as big as the moon is. It will get bigger and bigger until it takes up the night sky. Then our galaxy will merge with it. This is the only time you'll be able to see individual stars in the night sky from another galaxy but we will all be million billion years dead when that happens",
"You can't even see all the starts in our own galaxy. All the stars you see are next to us. I think you could see super novas from close by galaxies. But they are probably very rare in that range.\n\nObligatory [xkcd](_URL_0_)",
"Every light we see (That isn't a galaxy, Planet or some other phenomena) in the night sky is a star that is part of the Milky Way. Any specks of light that are galaxies, contain within that speck of light hundreds of millions if not billions of stars. They're THAT FAR AWAY.",
"Not with the naked eye. But there are stars within the milky way which originated in other galaxies and which have been consumed by the Milky Way. The gravity of our galaxy distorts the consumed galaxies into long ribbons of stars known as [stellar streams](_URL_0_), quite a few of which have origins as smaller galaxies.",
"there are only 3 objects that are outside of the milky way and visible with the naked eye: the two magellan clouds, which are dwarf galaxies, and andromeda, which is the closest (proper) galaxy.\n\nyou can not make out individual stars outside of the milky way.",
"How far away is the farthest star the average person can see on a dark night? "
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"https://en.m.wikipedia.org/wiki/List_of_stellar_streams"
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||
55hc40 | how is amazon able to fulfill such a wide variety of different types of product orders in such a short time (same day, next day, etc.)? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/55hc40/eli5_how_is_amazon_able_to_fulfill_such_a_wide/ | {
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"Amazon maintains large facilities all over the world stocked with common items. \n\nThis allows you to ship as short a distance as possible and consequently get same day or next day delivery.\n\nIf you look for something esoteric and strange you'll see that two day is about as fast as they can get to you. ",
"Amazon has a bunch of warehouses and hubs around the country. You order and its filled in the warehouse closest to you.",
"In addition to the other comments, I would also assume that anything marked as \"Prime\" would be readily available. ",
"Sort of yes. Few month ago i read article where it said that Amazon running new thing where it stocks their warehouses all over the places with most common(bought) items for that area, to be able to deliver same/next day. When they dont have it its 2 day.",
"In addition to the other answers, Amazon also predicts your future purchases due to the products you seemed to be interested in. Amazon then ships these products to the nearest possible facility. Thus its possible that when you buy a certain product, its already in a facility near you. "
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5rkr70 | how do crematoriums ensure only the one person's ashes are in the urn? | I can't for the life of me think of a way to catch the ashes left over from burning a body without scraping a little bit of someone else with them. A little help would be appreciated. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/5rkr70/eli5_how_do_crematoriums_ensure_only_the_one/ | {
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"They cremate the people one at a time in a given section of the crematorium.\n\nThey don't just pile in a bunch of bodies in a heap if they intend to actually keep each person's ashes.",
"I had a friend that worked for a local pet cemetery and he said all the ashes are mixed up. In fact they would burn several pets at once to conserve energy. ",
"Cremation remains are not ashes. They are pulverized remains of the skeleton, which isn't consumed by the pyre. \n\nThe more you know.",
"Mortician here!\nYou are correct, while we do all we can to get as much of your loved one as possible from the retort (dude oven), there's no way we can get every bit out. So yes, a tiny bit of remains is the remains of someone else. ",
"In 2002 in Georgia, a small family run crematorium was found to have distributed urns containing a mixture of burned wood chips and dirt, while at least 120 rotting corpses were found piled in sheds surrounding the property. Apparently their furnace had broken down, and the family couldn't afford to fix it. The state of Georgia only had 2 officials to run crematorium inspections at the time, so the deception wasn't discovered until an unlucky jogger happened upon one of the decomposing bodies, spurring an investigation.\n\n[source (NYT)](_URL_0_) \n\nUnrelated but interesting ",
"Haha a vacuum would be a good idea! No but generally all the remains left in the retort are then sweeped into a tray or pan at the end with a long broom. I guess you could picture like a long pizza oven, but you are pulling all the remains toward you (the opening). Then after it cools in the pan, you have to pick through it with a magnet (and/or your hands) to get anything that couldn't be burned, things like hip joint replacements or dental work, etc. pacemakers are removed prior to the cremation because they can explode in the retort! Next, the \"ashes\" will be chunky with bone fragments and what not, and since western culture is freaked out about seeing actual bones in their loved ones remains, we put them in a cremulator or as I like to call it a \"dude blender\". This grinds up the bones to a sand like consistency, so that everything looks nice if you take it out. :) "
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"http://www.metafilter.com/14859/Crematory-operated-for-years-without-burning-bodies"
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89qi0k | why do people still worship god in the 21st century? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/89qi0k/eli5_why_do_people_still_worship_god_in_the_21st/ | {
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"Higher meaning to life's existence. Spiritual experiences they've had. Faith is explicitly believing in something that you cannot see that is true. A sense of community and shared morals. \n \nThe list goes on.",
"Belief is linked to emotion, not to common sense.\n\nYou can feel the urge to \"believe\" without being convinced there is a deity.\n\nI'm firmly atheist because i dont feel this urge and when i view religion in my personal view, it doesnt make sense to me.\n\nBut plenty of scientists have practiced religion even though they couldnt \"prove\" there was a god.\n\nThere is also the social aspect of religion. \n\nIf you get certain bennefits by joining in the rituals of a religion, like a sense of community you get by attending church, then plenty of people choose not to think about the religion part too much and just \"go with it\".\n\nPersonaly I agree with a lot of the values a lot of religions promote, like respect, love and patience. But i dont feel the need to engage in rituals or to worship a deity in order to live by those values.",
"Children are easy to indoctrinate (brainwash) into believing, and once this indoctrination has occurred it is very difficult for someone to let go of their beliefs.\n\nThis is why churches and religious people make such a big effort to get to young children and tell them what to believe, through schools, Sunday schools, day cares, parents forcing children to go to church and read the Bible, etc.",
"Every single person has core beliefs that are a huge part of their identity. Changing these requires massive amounts of effort, and often the person reacts extremely violently/touchy when you try and change these. Our brains are basically wired to reject any that contradicts these.\n\nThese beliefs are almost always formed during childhood and can be everything from \"Math is stupid/useless I will fight you on it\" to \"the music I grew up with is absolutely the best and immune to criticism\" to political beliefs, cultural beliefs, prejudices, etc.\n\nReligion, because it's almost always introduced by the community/parents when the kid is very young, and the only real challenge often comes much later in the kid's life, is usually one of these beliefs."
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1a6p28 | what the hell is "rent-to-own?" | In what way is rent-to-own different than buying a product or house on credit/mortgage? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1a6p28/eli5_what_the_hell_is_renttoown/ | {
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"Say I want a new TV. I check Wal-Mart and Best Buy and find that the TV I want is $4500. I ain't got $4500 so I can't afford the TV, right?\n\nWrong. Rent to own places sell you on the fact that you can have that TV for only $78 a month. Granted, when you get done paying for the TV, it will have cost you over $6000, but you got the set you wanted without a credit check and without having to delay the purchase. Hell, most of the time you can pay a processing fee and get the first month for free if you ask. \n\nWith a home, it is a little different. You are renting with the option to buy. Every payment you make a little is going towards the purchase price of the house. When you decided to buy, you will still have to get a mortgage unless you rent the house for an agreed upon term. \n\nI used to work for a rent-to-own retail place. You would be surprised at the people who would buy stereos, video players and TV's and never look at the total cost. ",
"Rent-to-own - You pay a fixed monthly for the use of an item for a specified period of time, before you own the item. Up until that time, the item doesn't belong to you. The **store owns** the item. The store may take that item away from you. Similarly, you might decide you do not like the item and therefore return it to the store. You then stop paying installments and all is well.\n\nBuying-on-credit: You bought it. **You own** the item. However, someone loaned you the money for it, and you'll have to pay them that money back. If you don't, then and only then can they come and take that thing away from you. The guy you took the loan from may hate you but cannot do anything to what is now \"yours\" as long as you keep paying installments. Similarly, if you want to sell the item, you can. You can't just stop paying installments on your loan and all will be well.\n\nIn both cases, the basic idea is the same - you pay for something in chunks. However, when the thing becomes YOURS is different.\n\n(We can get technical about this, and it depends on the terms of the contract you sign.... but this is the best way I know to make it ELI5)"
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3x32i8 | if most of africa is so poor and wages are so low, why is everything made in asia and not africa? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/3x32i8/eli5_if_most_of_africa_is_so_poor_and_wages_are/ | {
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"wages being low is good for manufacturing, but having your factory under the control of various tribal warlords and having to bribe the various tribes constantly to avoid it being burnt down and all your employees killed is not good for manufacturing. ",
"Africa isn't very well industrialized, which creates a barrier to entry into the labor market. It could be done, but more (expensive) development would have to take place.",
"Corruption, war and difficulties to create companies or find employees with the knowledge, is some of the issues that Africa suffer.\n\nBut Asia, in other hands, don't suffer some of the same _URL_0_ least Japan, China and South Korea don't.",
"This is kind of interesting. China is actually investing in infrastructure on the African continent. \n\nThere is also a race between China and the US to get their foot-in-the-*African*-door: [source](_URL_0_)",
"If you build a factory in Asia and put machinery in it you get a factory with machinery in it.\n\nIf you build a factory in Africa, you have a half-built building with squatters living in it that you can dislodge, a bunch of construction workers being held for ransom by 3 different warlords, and all of your machinery mysterious fell off a truck somewhere."
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||
5a1fwb | why do multi-packs on amazon often cost more than buying multiple of an individual product? | I've seen this so many times where I'll go to buy something on Amazon where you can get a pack of 2, 3, etc... of an item and it's often more than the price of the item times that price (by quite a bit). If I buy multiple individual products though, I'll save money, why does this so often happen? I just saw it today with the Ozark 30oz Tumbler that made the front page. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/5a1fwb/eli5_why_do_multipacks_on_amazon_often_cost_more/ | {
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"text": [
"Could be an issue with the packaging. Depending on the weight of the goods they might have calculated their shipping cost on a bundle to be more since they might have to use a larger box or a different shipping service."
]
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[]
] |
|
6u9f6u | does energy have a weight or mass? | For example, does a battery weigh more when it is fully charged vs when it is empty? Or does a rain cloud weigh less after a lightning strike? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/6u9f6u/eli5_does_energy_have_a_weight_or_mass/ | {
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"Light (photons) doesn't have mass, but it has momentum.\nBatteries rely on electrochemical reactions to provide electricity. (A chemical reaction that produce electrons). Electrons do have a mass (although tiny) so a battery theoretically weight a little more when charged.\n[edit] for the reason cited below, not because of the electrons (thank you)\n\nAt a low enough level, [energy and mass become *kind of* the same thing](_URL_2_), particles ([such as the electron](_URL_1_)) can be 'weighted' in eV thus in joules. \n\nThis also means that \n[nuclear and chemical binding energy have a mass](_URL_3_): the product of an exothermic reaction will weight less than the reactants (the opposite is true for an endothermic one).\n\nFor example: we can see [from this table](_URL_0_) that breaking H-H bonds requires 436 kJ/mol or 4.52eV per bond.\nAn electron at rest is 0.511 MeV, so a H2 molecule is about 100-thousand-th of an electron lighter than 2 hydrogen atoms (meaning that the energy that hold a H2 molecule together weights 10^-5 electrons).\n\n",
"You're asking a **very** deep question. The answer is yes (mostly). \n\nA cloud has less mass because it does lose electrons. This is a static charge but it is more than just \"energy\" being lost. It's more like a waterfall that looses particles as it gives off energy. \n\nA battery doesn't lose electrons but it does lose electric potential which does alter the weight of the battery imperceptibly. \n\nEnergy is equal to mass (at an exchange rate of the speed of light squared)\nE=MC^2\n\nThe clearest example is nuclear decay in which some subatomic particles break apart resulting in smaller particles and some photons that don't add up in weight to their parent particle because photons are a massless form of energy. What exactly photons are and how they can be massless is a whole other thing. "
]
} | [] | [] | [
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"https://labs.chem.ucsb.edu/zakarian/armen/11---bonddissociationenergy.pdf",
"https://en.wikipedia.org/wiki/Electron_rest_mass",
"https://en.wikipedia.org/wiki/Mass%E2%80%93energy_equivalence",
"https://en.wikipedia.org/wiki/Binding_energy#Mass-energy_relation"
],
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] |
|
1kwfoj | why do people use the term "son" in a generic sense to address a boy but not "daughter" to address a girl? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1kwfoj/eli5why_do_people_use_the_term_son_in_a_generic/ | {
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"I'm not sure so don't take this as an answer, but maybe it's because daughter has two syllables as opposed to one. Daughter doesn't roll off the tounge as easily. I dunno though",
"It comes normally from mentor to apprentice. Men have a longer history of being artisans. "
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[],
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||
abxay9 | what is nitrous and how does it work? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/abxay9/eli5_what_is_nitrous_and_how_does_it_work/ | {
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"text": [
"Nitrous oxide has more oxygen in it. More oxygen means more fuel means more explosion means more power. ",
"An internal combustion engine works by mixing air (oxygen) with gasoline and then igniting the mixture to cause an explosion.\n\nNitrous Oxide (chemical formula N\n2O, two parts nitrogeon to one oxygen), when added to the air/fuel mixture it provides even more air, which means more fuel can be added, this results in a bigger explosion and thus more power.\n\nThe issue with using it is that the engine needs to be very strong to withstand the extra pressure of those big explosions, it is also vital that the fuelling is correct - if the engine runs too lean (i.e. the mixture has too much air/not enough gasoline) the engine will become very hot and literally the insides of the engine (typically the piston) will melt.\n\nBoth the German luftwaffe and British RAF experimented with Nitrous in WW2 to give aircraft engines a momentary power boost. Of course it became irrelevant for aircraft as piston engines were dropped for jet engines.",
"Air has a nitrogen/oxygen ratio of about 4:1. Nitrous oxide has a nitrogen/oxygen ratio of 1:2. Combustion relies on oxygen, and so the density accelerates the reaction.\n\nCars using a nitrogen system will have tanks of NO2, and plumbing from the tank to a solenoid, which is just a valve that's actuated by a motor. The solenoid typically sprays into the intake port - air comes into the engine, past an air filter and through some ducting into an air box on the top more appropriately called an intake manifold. The air is channeled down more ducts, called ports, down to the intake valve that opens up into the combustion chamber of each cylinder. At the push of a button, the solenoid opens and nitrous vents into the port; when the intake valve opens, the positive air pressure force feeds enriched oxygen atmosphere into the cylinder.\n\nEDIT: I should note, the gas looks like a fog when it comes out. It's super cold droplets of gas because it's expanding - and expanding gasses get colder. This is a good thing, because cold air is dense air, meaning you're getting more oxygen into the cylinder for combustion.\n\nOstensibly, after combustion, the gases are vented out the exhaust port, and those gasses flow past an O2 sensor. The engine gets a signal that the fuel/air mixture is too lean, and so it compensates by spraying more fuel. This is called \"closed loop\".\n\nIn actuality, when you mash the gas, the computer stops trying to be fuel efficient, it stops trying to be EPA compliant, it just dumps as much fuel as it possibly can into the air stream. This is called \"open loop\".\n\nSo when you're running a nitrous system, you need a fuel system that can deliver enough fuel to react with all the additional oxygen. Gasoline will burn completely with an air/fuel ratio of approximately 14.7:1. More air means you run lean, less air means you run rich. Lean combustion is extra hot and produces bad emissions, running rich is actually a way to cool the engine internals, as the unburnt gasoline vapors will take internal heat with it out the exhaust, but it's certainly not fuel efficient.\n\nThe reason you would do all this in the first place is because someone else said it to me best: \"If you want to make 800 hp, you need to consume and combust 800 hp worth of air.\" There are many ways of doing that, either by a bigger engine with more volume, or running an engine faster so it breathes the same amount of air as a bigger engine in the same amount of time, or by force feeding air into an engine as with a turbocharger, supercharger, ram air, or nitrous."
]
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3seo6o | if it's legal to jack up life-saving prescription prices, why is it illegal to sell my life-saving organs? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/3seo6o/eli5_if_its_legal_to_jack_up_lifesaving/ | {
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"Its illegal to sell your organs because that very very quickly starts abusing poor people. Rich people who are sick could essentially just at will put pressure on poor people to replace organs of theirs. Do we really want to live in a society where we can essentially blackmail poor people to give up their organs?\n\nPrices on life-saving prescriptions can go up because well, its a business. Things change. Maybe there are legitimate reasons to charge more for the drug (like the need to fund research for new drugs). Whether or not its ethical I dunno. Theres certainly issues with it but theres no good solution. Its definitely less clear cut than selling organs.",
"Because you are not a card carrying member of Club Med and have not spent tons of money getting a Congress highly compliant to your wishes.",
"Hypothetically, it's because there are very few financial R & D costs associated with cutting an organ out of someone and putting it into someone else, whereas developing a drug and receiving FDA approval is often a multi-billion dollar investment (that can get tanked at any point in the process, rendering it a complete waste of money). In an effort to keep drug companies performing this relatively expensive, but totally necessary, task, we allow them a substantial amount of freedom with regard to pricing and patent law. \n\nA secondary reason is scale. Basically, a drug company large enough to develop, manufacture, and market a drug will almost certainly be a scrutinized, publicly-held, multi-billion dollar company. An organ-harvesting company, though, could be started by a few entrepreneurial individuals if we started paying for organs on a \"per-organ\" basis. When a business depends on the harvesting of organs to increase their bottom line, market forces will tend push them increase the number of organs they harvest. If we were talking about 10 or 12 giant companies, enforcement of legal harvesting (e.g. voluntarily, from the recently deceased) would be a relatively straightforward proposition; however, since there would more likely be thousands of little tiny companies, illegal harvesting (e.g. from homeless populations) could become a problem. \n\nFinally, and probably most convincingly, organs are an intrinsic part of the human body, whereas drugs are assembled from molecules existing in nature. Basically, we *make* drugs from stuff, but we have to *take* an organ from someone else's body...and they're usually putting it to pretty good use already.\n\nThe student loan situation SUCKS, though...One thing you might consider investigating is [loan forgiveness](_URL_1_) - depending on your degree, certain employment commitments can net you reductions in the amount you owe to the Federales. At the risk of getting a little too political, you can also vote for Bernie Sanders, who is advocating for a substantial reduction in borrowing rates for people in your position.\n\nIf you're still reading, though, you're clearly desperate...Maybe you [go to Iran](_URL_0_)? "
]
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[],
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"http://www.cato.org/publications/policy-analysis/organ-sales-moral-travails-lessons-living-kidney-vendor-program-iran",
"https://studentaid.ed.gov/sa/repay-loans/forgiveness-cancellation#teacher-loan"
]
] |
||
2477od | why is aspirin so much cheaper than other nsaids? | I was just in the store and noticed that aspirin is about 20% of the cost of other NSAIDs (ibuprofen, acetaminophen). What is going on here? Government subsidy? Cheaper ingredients? Capitalism? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2477od/eli5_why_is_aspirin_so_much_cheaper_than_other/ | {
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"Aspirin has been produced synthetically for over 100 years, there are no patents on it, and any brand can use the name Aspirin legally.",
"Looking at their methods of synthesis, Aspirin requires a low number of steps and is therefore probably cheaper to produce.",
"In the UK they're all around the same price if you buy cheep stuff from Tesco or some other shop like that. Also just little heads up [acetaminophen (paracetamol)](_URL_0_) isn't a NSAID and you can take it in combination with other NSAIDs ",
"Aspirin is made in a single step from an esterification reaction of salicylic acid and acetic anhydride. This is a simple reaction, and both reagents are common, easy to get and cheap. \n\nIn comparison, ibuprofen is made in three steps, and if you lose a little with every step the overall yield (how much of the final product you get out, compared to how much stuff you put in, and all by-products formed) is lower. More work, and less product means a higher price. ",
"Aspirin was patented in 1900 in the US and the patent expired in 1917.\nAspirin was a Trademark protected name until 1920.\n\nAfter these dates expired any one could make and sell Aspirin. Not just the Bayer, the Original owner of the patent and trademark.\n\n[Mildly interesting History.](_URL_0_)\n\nIbuprofen was patented in 1961, and I think the patent is still in effect.\n\nAcetaminophen is not generally classified as an NSAID because it exhibits only weak anti-inflammatory activity. But The U.S. patent on it has long expired, although certain Tylenol preparations were protected until 2007. U.S. patent 6,126,967 filed September 3, 1998 was granted for \"Extended release acetaminophen particles\"."
]
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[],
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|
a3byf9 | why can't yogurt cups be recycled? | Aren't they plastic? What's different about yogurt cups that recycling centers don't want them?
| explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/a3byf9/eli5_why_cant_yogurt_cups_be_recycled/ | {
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"It depends but usually yoghurt and also coffee cups (take away) use both paper and plastic in the same product (thin layer of plastic to stop the product let liquid out) and it is really hard to separate them so they are usually not recycled. But as I said it depends on the product package and also the way/machines recycling is made.",
"Yogurt cups are typically made from polystyrene, which can be recycled, for example into extruded polystyrene (the white, fluffy stuff used for packaging and insulation).\n\nHowever, it might be that it's not profitable enough to do so. In that case, it would be burnt in an incineration plant as fuel anyway."
]
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[],
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cfgbnz | what is the legality around a tv film crew filming illegal activities? like filming heroin production and smuggling across country borders. or addicts buying and using meth? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/cfgbnz/eli5_what_is_the_legality_around_a_tv_film_crew/ | {
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"text": [
"It’s not illegal to film it. \n\nSimple as that. Now of course what those people are doing may be a crime, but simply filming it occurring is not, unless you’re somehow also doing the illegal stuff you’re filming. If the camera man sticks a bag of coke in his pocket to smuggle it across the border, that’s illegal. Video taping a guy putting a bag of coke in his pocket is not.",
"Very few people in America are bound by “duty to report” laws. For example, a schoolteacher is legally obligated to report suspect child abuse, but there is no law saying TV crews must report drug deals. Further, there are strong legal protections for journalists. They can also claim the portrayal was fictional or a re-enactment. \n\nIf the police observe a crime on TV and want to investigate, they are welcome to it. But they can’t bring the film-maker to court just for filming it.",
"They're journalists/reporters, in most countries, they are considered doing they're job. Not illegal.",
"22 years in TV news (US). \n\nWhen seriously working on a journalism assignment, this not necessarily illegal.\n\nBut, as a journalist, one cannot actively assist or enable the illegal activity. It’s important to act as an observer only. \n\nAlso, if someone’s life may be in danger, ethics may require you to notify authorities as this exceeds the journalistic value of the story. \n\nThere is A LOT more to this discussion with many, many exceptions, situations or levels of illegality that nullify my basic assertion. \n\nBut, for journalists and documentarians, there are many situations and examples where recording of illegal activity is not considered illegal."
]
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4fwtk8 | why does a $500 guitar sound different than a $10,000 guitar? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/4fwtk8/eli5why_does_a_500_guitar_sound_different_than_a/ | {
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"The whole thing starts from the strings. They resonate and produce the sound.\n\nNow, the strings are attached from both ends to the guitar. The material and the attaching mechanism both affect the sound by subtracting frequencies from the original sound. For instance, the nut which is the part in the beginning of the fretboard affects the sound quite a bit. To illustrate, take a small piece of plastic and drop it on your table. Listen to the sound it makes. Now, take a coin and drop it on the table. It's a totally different sound!\n\nAfter the strings and their first touch points comes the rest of the stuff, for example how the bridge is installed to the body and what kind of tuners the guitar has. These affect the sound the same way as the first parts.\n\nNext, there's the wood. The fretboard affects the sound quite a bit because you press the strings against it when you play the guitar. The wood must be able to carry the sound well and not cut it down - this is why many high-end guitars have ebony fretboards; it's really hard wood and carries the sound really well.\n\nOnwards... The way the neck is attached to the body is a major factor as well. When the whole guitar is made from \"one piece\" (they rarely are, but instead are glued from multiple pieces), the sustain of the sound gets better compared to bolt-on necks.\n\nWhen you factor in all the little things that affect the sound, you get a list of things musicians generally want, and these affect the prices. A guitar with an ebony fretboard, solid body, selected nut, quality tuners and bridge and high-end pickups will generally cost quite a bit more than a simple guitar with maple fretboard and the cheapest bridge and tuners you can get."
]
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||
32x9jo | how do "turns white when it's clean" foam cleaners work? | Products [like this one](_URL_0_) that claim to clean a surface just with application of the product. What is actually going on here? Is the color change simply oxidation, a chemical reaction in the cleaner, or is there actually some reaction with whatever is on the surface this is sprayed upon that causes the color change? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/32x9jo/eli5_how_do_turns_white_when_its_clean_foam/ | {
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"text": [
"I'm pretty sure its a chemical reaction of an additive when it reacts with air. other chemicals do the cleaning. This just provides a timer so people know when it is time to wipe it off."
]
} | [] | [
"http://www.scrubbingbubbles.com/Products/Pages/Bathroom-Cleaner.aspx"
] | [
[]
] |
|
2bwt00 | if when we delete things, our computers just allow it to be overwritten (it doesn't actually delete the data), what's in the "free" space before there's actually data we put in there ourselves? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2bwt00/eli5_if_when_we_delete_things_our_computers_just/ | {
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"When we first get the drive, it's just zeros.",
"A conventional hard disk is divided into two parts which are managed by your computer's *filesystem*, 1) files containing data, and 2) a description of the directories and files, organized by name. So if you are on a Mac, and you open up\n\n /Users/bill/Music/iTunes/iTunes Music/Badfinger/Straight Up [Bonus Tracks]/Day After Day.mp3\n\nyou are traversing those descriptions, first for folders (aka directories): /Users, then bill within /Users, then Music within /Users/bill, etc. Then you reach \"Day After Day.mp3\". At that point, the description is not of another directory, but a file, identified by the location of a file on disk. The file is a sequence of bytes, containing the file's contents.\n\nWhen you delete the file, you are modifying descriptive information. If you delete \"Day After Day.mp3\", (which would be dumb), then the description of that file is erased. The location of that file is recorded elsewhere as free space, (which you can think of as another part of that descriptive structure, #2 above).\n\nSo the file contents are still there, but you can no longer find it traversing through your directory structure. Eventually, that locations of that file may be used to store some new file, in which case the bits of \"Day After Day.mp3\" really are gone, reused to store some other file.\n\nForensic tools can crawl through this space and find file content that is in free space and has not been reused. People who don't want forensic tools to find deleted files do \"secure\" deletes, in which random bits are scribbled over the file as part of deletion. (This is actually not foolproof, depending on the filesystem in use, and the disk hardware.)\n\nOne major simplification in this explanation involves the Trash folder. On a Mac, at least, when you move a folder to the Trash, you are simply moving the description to a different directory. That space is not considered free until you empty the Trash, and at that point your file is free-space fodder as described above.\n\nWhat's in the free space before anything is written there? I'm actually not sure if its random bits or zeros, but it's the same idea -- available disk space is noted by the filesystem."
]
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||
3ym86j | where do the extra commercials in overtime/extra innings sporting events come from? | In football and baseball they plan for so many commercial breaks and the network fills that ad space. If the game goes into overtime or extra innings who gets that ad space? It would arguably be the most coveted ad space given the exciting game. Do they sell it at a premium and give a refund if the game ends in regulation? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/3ym86j/eli5where_do_the_extra_commercials_in/ | {
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"text": [
"They will sell the ads to the advertisers in advance. The ad order might say something like \"one ad during each quarter, and one in each overtime as available.\n\nAdvertising like this is billed after it runs, so there wouldn't be a refund, they'd just only bill for for ads if they actually run. "
]
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|
1imngu | the tau manifesto, why is pi wrong? | _URL_0_
As someone who's just beginning calculus, all of the proofs provided are going right over my head. It seems like they'd rather use twice the radius of a circle, rather than its diameter? I guess those aren't equivalent?
Can anyone take a shot at cluing me in? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1imngu/eli5_the_tau_manifesto_why_is_pi_wrong/ | {
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"They are equivalent.\n\nIt would appear that the issue entirely revolves around the fact that 2pi is used in a lot of places and the author thinks this weird enough to warrant shifting to tau. \n\nI would point out that in electronics, current flows from positive to negative while the actual electrons flows from negative to positive. Science and maths is full of weird tidbits like this.\n\nPersonally, pi works.",
"Tau is just 2pi which i'm sure you've noticed in many calculations. The issue is that many people think using tau would make things easier/less complicated. Other people say that we are so used to using pi that it would be stupid to change now. They both work equally well, so it is mostly just a big battle of preferances. For me personally i would love to use tau, but i fear that my teachers wouldn't recognise it and mark me wrong."
]
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2pfpcq | is current tension between russia and united states similar to the scenario before world war started? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2pfpcq/eli5_is_current_tension_between_russia_and_united/ | {
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"Could you mean the Cold War? The United States and Russia were actually allies in World War I and II.\n\nBut at the end of World War II, with the destruction of Germany, Italy, and Japan, the only two superpowers left in the world were the U.S. and Russia. Tensions were extraordinarily high after World War II, primarily because both the U.S. and the Soviet Union (Russia + some countries it took control of) both wanted to be the supreme super power, have the most influence globally, both in terms of politics and economics, and it was ultimately a competition between capitalism/democratic republicanism and authoritarian communism.\n\nRussia ultimately gains a huge amount of influence in East Asia, primarily in China, who then gains influence in Korea and Vietnam, which led to the proxy wars there. They're called proxy wars because those wars were actually U.S. vs Russia, but they weren't fighting directly. A lot of this coalesces at its most dangerous point when Russia put nuclear missiles in Cuba and was prepared to target the United States. Fortunately this never happened.\n\nThe United States eventually won out when Nixon (yes, Nixon) ended the Cold War. He did this by ending the alliance between Russia and China, which was, by this time, Russia's final ally that had any comparable power to the United States, and ultimately the Soviet Union fell apart, largely due to internal struggles and the failure of Communism. Reagan gets credit for ending the Cold War because he was all \"Mr. Gorbechev, tear down this wall!\" but that was an inevitability anyway.\n\nAt any rate, the short answer is no. There are certainly tensions between the U.S. and Russia, but they are not even close to what they used to be. This Ukrainian crisis has upped the ante a bit, so to speak, but it's still not even comparable."
]
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||
1ok1qi | if the united states got invaded today, what would happen? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1ok1qi/eli5_if_the_united_states_got_invaded_today_what/ | {
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"Considering America is the only super-power they would most likely repel the attack. Also there is this thing called nukes, that kind of prevent this as the aggressor would be annihilated. ",
"The attempted invasion force would be obliterated, and the invader home country would soon glow with the warmth of a green sun. ",
"By who, aliens?\n\nThere is no country in the world that has the projective military power of the US. With their air and missile defenses, it is unlikely any country besides Mexico or Canada could get military forces anywhere near the mainland.\n\nWithout being more specific, it is not a question that can be answered."
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1u4id1 | why don't we all celebrate new years at the same time, because our position on the earth doesn't change when it's complelted it's rotation? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1u4id1/eli5_why_dont_we_all_celebrate_new_years_at_the/ | {
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"Because we don't want our local days to be divided between years and we want our calendar days to line up with our local day/night cycle (instead of having the 'day' switch at, say, dinner time). Since we allow different places to have the day start at different times and our year is defined on the transition to a certain date, this means that the year changes at different times in different places. It can be quite frustrating for anybody working internationally or trying to make dates and times work correctly on computers, but to do it all together would likely frustrate people in other, subtle ways."
]
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||
4eff11 | how does volume work, its affect on quality and difference of different volume changers? | How does volume work when we increase or decrease it?
How does it affect the sound quality? or is it only based on speaker?
When we change volume from different sources how do they cooperate; what I mean is we can change a video volume by video player(example: youtube, spotify) and from pc's volume at right bottom, do they overwrite each other or multiply its values etc? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/4eff11/eli5how_does_volume_work_its_affect_on_quality/ | {
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" > How does volume work when we increase or decrease it?\n\nThe amplitude of the signal is scaled up or down. This corresponds to the movement of the speaker membrane - so if the volume is higher, the speaker membrane moves faster and further. You do this by multiplying the signal with a large or small number respectively, e.g. multiplying amplitude by 0.5 halves volume.\n\n > How does it affect the sound quality? \n\nIdeally, not at all, but if implemented in a sloppy way, it can significantly reduce sound quality. Digital audio is represented by a series of numbers representing the amplitude of the signal, called \"samples\". If you already use a small size for these samples, e.g. 8 bit (0-255), and you then divide it by 10 to reduce volume to 1/10th, each sample is a number between 0 and 25 - which is completely inadequate. \n\nFor that reason, CDs use 16bit samples, that is numbers between 0 and 65535, which is so high that you still end up with perfectly fine quality even after cranking down the volume.\n\nEdit: Adjusting the volume at the amplifier should not affect audio quality like that. However, amplifiers typically don't work well in their extremes, meaning that very quiet and very loud settings usually have worse quality.\n\n > what I mean is we can change a video volume by video player(example: youtube, spotify) and from pc's volume at right bottom, do they overwrite each other or multiply its values etc?\n\nThey multiply. It just doesn't seem to be like that because of our logarithmic perception of volume: What we perceive to be twice as loud is actually roughly a tenfold increase of volume, or a change of 10dB. ",
"Increasing the volume (amplifying a sound) does not typically reduce the quality, but it will result in background noise being amplified as well. \n\nSo if you record silence and then amplify it by several decibels, then very soft background noise that was imperceptible before will suddenly become incredibly loud noise.\n\nIf a recording (e.g. of someone's voice) was originally very soft then again amplifying the recording will make the recording louder, but it will also make the noise louder so the recording won't really be any clearer; just louder to the ears.\n\nThere is, however, a limit to how much you can amplify a sound. If you amplify a sound beyond that limit, it will cause 'clipping'. When clipping happens, basically the audio waveform gets distorted and the peaks and troughs of the waveform essentially get cut-off. So you end up losing that information from the sound and this results in noticeable distortion or degradation in quality.\n\nA lot of amplifiers and professional audio gear will have volume unit meters or indicators that will show you if the amplification level is too high and causing the audio to clip (see [here](_URL_1_) or [here](_URL_3_) for an example).\n\nSoftware applications for editing audio can also show you if your digital waveform is clipping (see [here](_URL_2_) for an example).\n\nTo answer your question about multiple volume controls on a computer. It doesn't really matter what the software (e.g. media player volume) is set to as long as it's not set to > 100% or configured in a way that allows clipping (the VLC media player, for example, allows you to exceed 100% volume).\n\nSo if you keep the player on the max/100% setting and then adjust the system volume level to your desired listening level, that's fine. Or you can do it the opposite way (set the system volume high and adjust the media player volume to the desired level). Just don't allow any of your volume controls to exceed 100% or otherwise get to the point where the sound is clipping.\n\nNote: some media players have volume controls that are tied to the system volume so adjusting the media player control has a direct effect on the system volume level.\n\n[This](_URL_0_) is an example of what clipping can sound like (starts half-way through the video). Clipping is not always as pronounced/obvious though, it could be far more subtle."
]
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"http://www.realhd-audio.com/wp-content/uploads/2013/12/vu_meter.jpg"
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tlj6n | - knot theory | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/tlj6n/eli5_knot_theory/ | {
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"How many different ways are there of twisting two loops together? how many look different, but are essentially the same? how complicated can we get? what if we use more loops? what if we knot different shapes together? \n\nIf you want specific answers, you should ask more specific questions.",
"Well, there's a lot of it. Is there anything in particular you want to know. I'll give a few basics.\n\nFirst, lets be clear on what a knot is. Mathematically, a knot is a line twisted through space in some way so that it ends up where it started - that is, it's at least a loop. The simplest way is the [unknot](_URL_2_), which is clearly just a circle, though you could deform it and it would still be an unknot.\n\nBut we know that there are more knots. A simple one is the [trefoil knot](_URL_0_). It definitely looks different to the unknot, right? But how do you prove that? How can you be really sure that one knot is not the same as the other if you shook it around a bit?\n\nThe answer is that you need some kind of *knot invariant* to describe the knot. That is, some number or equation that is always the same if you calculate it for a given knot, so you can shake it about all you like without that equation changing. If two knots have different answers when you work out the equation, you must have proven that they're different knots, otherwise they'd have to have the same one.\n\nThere are a few obvious things to try first. For instance, you might have the idea of arranging the knot so that it has the fewest crossings possible. For instance, the trefoil knot above has 3 crossings, and you can't arrange it so that it goes over itself fewer times than that. The unknot has 0 crossings, though, so using this measurement they must be different! Except we haven't quite *really* proven anything here, because we haven't *proven* that we can't arrange the trefoil to have fewer crossings, even if it seems obvious. This also isn't a very useful measurement because if you have a really complicated tangle it's hard to work out how to arrange it with the fewest crossings.\n\nSolving the 'are knots the same' problem was eventually solved by discovering algebraic knot invariants. With these, you can look at a knot and write down a polynomial (like x^2 - x + 1) for the knot that doesn't change even if you shake it up. The first one found was the [Alexander polynomial](_URL_1_), but nowadays we have loads, including ways of generating more. This allows people to categorise knots quite easily, and there are even big tables of all the knots with a certain number of minimum crossings.\n\nAs with all big mathematical theories, knot theory has expanded massively and is very mixed up with all sorts of other things. For instance, the mathematics of quantum field theory in physics turn out to be in some cases very intertwined with knot theory by asking whether particles move in knotted paths."
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2hcvbt | with more people and less jobs, how will future generations all find employment? | With recent publications predicting that the world population will reach 11 billion by 2100, how will future generations all find work? As technology permeates (and partially replaces) the job market not only in first-world countries, but "emerging countries" as well, will this not create a large issue on the whole? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2hcvbt/eli5_with_more_people_and_less_jobs_how_will/ | {
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"More people means more demand means more production and civil service jobs. It's always been this way.\n\nIf one task is eventually automated, hopefully the excess workforce will be put to performing more complex tasks.",
"They won't. There will be a huge underclass of low skill citizens who live a marginal life.\n\nEducation is increasingly becoming more expensive and out of reach. It will be very competitive.\n\nI used to work as a cashier and at Blockbuster video. Those jobs are gone. Kids these days don't have as much choices. Plus immigration has created a bunch of low wage workers that are actually more skilled than their pay would reflect. An American teenager can't compete with a Central American laborer who has decent construction skills.",
"It will create a massive employment issue - one we really don't have the answer to at this point. Think of some of the largest employment areas in our economy: transportation, food service, agriculture, etc. These are all areas where people can not only be replaced by computers and robots, but the robots will do a significantly better job. \n\nFast forward 50-100 years, I see employment being considered less of a necessity and more as an option. There will be a large portion of the population that is on government assistance while a smaller portion pursues professional or artistic careers. Being unemployed will not be stigmatized, it will be a common lifestyle. \n\nWhen the robots do everything, most people will have nothing left to do. ",
"They may not. Read The Lights in the Tunnel:\n\n_URL_0_",
"I read a theory that once humanity is past a point of need we'll turn into a society of artists and thinkers and whatnot. We won't need to have money or jobs, we'll have progressed beyond it. ",
"By the year 2100? I'll be dead, so I don't care.",
"We will probably have something like /r/basicincome. But I imagine people will still want to work so they will structure themselves around local economies. Hand made goods, food, starting small businesses etc. ",
"If you haven't read [this](_URL_0_), read it. It explains everything and it will explain everything. Seriously, just read it. Read all of it.",
"It has different names but the idea is the same. Basic Income. Social Wage. Citizens Income. Negative Income Tax. You get a small but livable income for no other reason than you exist. No means testing. Bill Gates Qualifies.\n\nok, we're realist enough to know that this not for the entire world yet. So there are some caveats. Let's say 21 years of proven residency in the country, then you qualify.\n\nThe right hate the the idea because it allows poor people to do bugger all without working. The left hate the idea because poor people get income without the state dictating how they live their lives. Gradually, people of the middle are coming around to the idea that nothing else will work long term."
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8ulg3y | the difference between chlorine bleach, hydrogen peroxide, and rubbing alcohol in their antiseptic properties | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/8ulg3y/eli5_the_difference_between_chlorine_bleach/ | {
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"Source: am biotech engineer\n\nBleach (sodium hypochlorite) is an oxidizing agent, so it destroys cells on a molecular level. You know when iron is converted into rust by air? Yeah bleach does that to bacteria and oxidizes all their proteins. 10 minutes of bleach is enough to fully sterilise anything.\n\nHydrogen peroxide is an even more powerful oxidizing agent. It is unstable and will rapidly decompose into oxygen, showing how reaction it is. Any concentration above 35% is potentially lethal on touch, as it will burn through your skin, muscles and nerves like it was a fizzy tablet in water. Most household bottles have only 3% concentration, so it’s safe-ish to use while still killing bacteria in seconds. Also, please don’t put hydrogen peroxide on your wounds. It does kill bacteria but your cells die too.\n\nRubbing alcohol (isopropyl alcohol) is the weakest of the 3. At 70% concentration it is the most effective, able to kill some bacteria by dehydrating them. Unfortunately, it doesn’t kill all strains of bacteria. Some bacteria are just placed in “stasis” when dehydrated and will happily come back to life when it is wet again. It should be good enough for common day use but most biotech laboratories have phased it out in favour of bleach."
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5qtf9d | why does america not want social policies like europe? | As an Irish person, it seems crazy to me as Ireland has a lot in common with America, policy wise but this is something I've seen over the years and still don't get.
I know there is the tax element but you have that in European countries too. Irish people hate paying tax and seeing the money wasted but it doesn't make us not want social policies that stop people dying. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/5qtf9d/eli5_why_does_america_not_want_social_policies/ | {
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"Because politicians use scare tactics: your taxes will go up, you'll get sub par care, you'll wait hours in the emergency room, you won't be able to choose your doctor, etc., etc. Those are the things you hear when people fight against universal healthcare. \n\nIf you need to apply and benefit from a social program, like food stamps, you're called lazy, assumed to be an addict, given looks in supermarkets and people try to tell you what you can and can't feed you or your family. When in reality, studies show most are not on drugs, most states REQUIRE you to have a job or be disabled to get food stamps (so the workers are technically being taxed twice for food) and the money that citizens pay towards food stamps per year averages to about $40/yr. \n\nI think it's great that we have a capitalist society, but when someone cannot work due to injury, disability or illness, there needs to be something in place to help them. People shouldn't have to live in poverty and be judged because they had the misfortune of getting sick or are working their ass off at a job that won't pay a living wage. \n\nPolitical propaganda spreads lies about the social programs we have now and also about foreign social programs. Lies that make what we have seen a ton better when in reality, our neighbors across the pond feel pity for us because we DONT have universal healthcare, paternity leave for new dads, and free education. \n\nThis is why.",
"The fact is that a significant portion of Americans either do not want the same political or cultural policies or norms of Europe, or at very least, do not see the government as the proper institution to bring about these changes. We want different things than you.We value different things, enjoy different things, have different expectations from our governments. "
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4pmprs | hayfever: how come, even with all my doors and windows closed, i still wake up in the morning with hayfever? | How does it get inside the house and upstairs? Is there any way to minimise hayfever symptoms? Thanks all!
EDIT: Thanks for the answer. Obviously the house isn't airtight, but I'm always amazed that pollen finds it's way from outside in through the gaps, along the hallways, up the stairs and into the bedroom (and going by my symptoms, quite a lot of pollen as well). | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/4pmprs/eli5_hayfever_how_come_even_with_all_my_doors_and/ | {
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"Do you have air conditioning? Did you seal the bottom of your doors? Are you running a positive pressure internal system?\n\nYour house is not air-tight by any means.\n\nIf you do have A/C, get new filters. Might also consider a large room HEPA filter for wherever you spend most of your time. Also might consider seeing an allergist for better treatment.",
"If your house was air tight you would use up all the oxygen and die. Your house is by no means airtight. You can go for the HEPA filter generating positive pressure. But the allergist may well be cheaper."
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8lkifw | a car with constant speed means sigma force=0, but yet i will feel the pain, why? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/8lkifw/eli5_a_car_with_constant_speed_means_sigma_force0/ | {
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"It's not about the acceleration here. It's about Momentum.\nWhen the car hits you, it brings about a change in its momentum in a short time (called impulse). That change in momentum (i.e. impulse) gets transferred to your body. Consequently, your own momentum shoots up from zero. And THAT is the force you experience.\n\nGiven how heavy the car is versus you, a small change in the car's momentum will still be a large impulse",
"Yes, according to Newton's equation F=M\\*A, a car moving \\(with no friction or air resistance\\) at constant velocity means that no forces are being applied to it. If you were to push the car in any way, then it will accelerate in the direction of the force.\n\nHowever, if the car were to hit you, then two things will happen; first, the car will apply a \\(large\\) force on you making you quickly accelerate in the direction that the car was moving; and second, you would apply an equal force on the car making it \\(de\\-\\)accelerate. Both forces will be equal and opposite. Since your mass is much less than the car's, your acceleration will be much greater than the cars.\n\nA car moving at a constant velocity may have no force on it, but it still has kinetic energy equal to it's mass times the square of it's velocity. Oh yeah, you will feel pain."
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4xo7yp | why does stress and tension manifest in tight muscles? and furthermore, what happens during a massage to relieve that tension? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/4xo7yp/eli5_why_does_stress_and_tension_manifest_in/ | {
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"Tight overworked muscles with weaker antagonists are chronically shorter and this leads to posture pain and biokinematic dysfunction. Massaging physically relaxes the muscles and moves waste products (lactic acid, dead blood cells etc) to the nearby lymphatic system vessels (bodies drainage system). Massaging can also release nerves and connective tissue like stretching. \"Knots\" or trigger points are specific points in the muscle that are more painful, tender and seem to feel better after constant tension is applied to them. Activating and working underused/dormant muscles is another part to the puzzle but topic for another conversation."
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||
whjqr | why if i put the + of one battery to the - of a different battery does nothing happen? | So as I understand it, electricity goes from the + to the - because the - side has a bunch of electrons and + needs them and a long time ago someone made a bad call and said that electricity flows against the electrons. Ok, fine, + needs electrons, - has got them, you connect them on the same battery, sparks fly because electrons are moving really fast. Makes sense to me.
But why when I take the - (has electrons) one battery and connect it to the + of a different battery (needs electrons) does no electron business happen? What is the difference? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/whjqr/eli5_why_if_i_put_the_of_one_battery_to_the_of_a/ | {
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"You need to have a full circuit. Here's an analogy:\n\nThink of electricity like water and the battery as a pump. If you put two pumps next to each other but dont loop it, the water wont be able to keep flowing through and back to the first pump again; won't be a cycle.\n\nIt's nothing like that but if it helps you to understand it, that's fine. So, if you touched the batteries together and then put a wire from one end of the two batteries to the other, it'll work. However, you'll get a short circuit and make some sparks so not good idea."
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2dqf37 | why are things like sex and drugs difficult for some parents to explain to their kids? | I am not a parent, but I often see situations where the parents give each other that awkward look when little johnny asks where babies come from. The parents give some unhelpful answer that makes everything more confusing. Why is it such an issue? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2dqf37/eli5_why_are_things_like_sex_and_drugs_difficult/ | {
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"Most parents don't like thinking of their kids as sexual beings, and drugs are generally taboo in most mainstream circles anyway.\n\nYou ask her dad for permission to marry his daughter, not for permission to sleep with his daughter.",
"The US has this sexual repressive society.\nI noticed it on the internet too despite all the porn.\n\nPeople just fear talking about sexual things mainly due to the way our current society is, it's not just parents.",
"As a parent I would say its differcult to talk about sex and drugs to children because the issues are very complicated and it is easily misunderstood by the children. I have never ran into a parent that would not tell a child something that was biological in nature. But....most kids ask questions and those questions are either misunderstood by adults or the child was sayingv it wrong.\n\nSix year old John asks his mother, \"Where did I come from?\"\n\nMother knew this day was coming and sat John down and explained sex the best she could.\n\nAfter, John says, \"No. Bobby said he came from New Jersey. I wanted to know where I came from. \" ",
"They might not want their child to actually try it, and they can't do that if they don't know what it is."
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6ts70j | what would happen if you just drank soup for the rest of your life? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/6ts70j/eli5_what_would_happen_if_you_just_drank_soup_for/ | {
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"It's possible to live of liquids. Maybe not soup specifically but solid food isn't necessary to keep one alive "
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5lo88z | how does an organization like the ku klux klan still exists and operates in america? on what basis? constitutional? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/5lo88z/eli5_how_does_an_organization_like_the_ku_klux/ | {
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"The constitutional rights to assembly and free speech both allow organizations like the KKK to exist. In the US, being racist is perfectly legal. As long as you don't harass specific people, or break any actual laws, you're allowed to be as hateful as you want. And the KKK doesn't break laws these days.",
"They're allowed to think and speak whatever they like, and are constitutionally protected. They just can't act on their hatred, legally. ",
"Anyone in the US has the right to peacably assemble per the 1st ammendment to the constitution.\n\nThis is true regardless of how offesive the views of the assembly are.",
"Essentially the constitution, yes. As long as they don't get violent they can essentially do whatever they want. Contrary to popular believe, yes, hate speech is protected under the first amendment. The exception to free speech is \"fighting words\", meaning if you walk up to a black person and start screaming the N word and berating him for his race, then your speech isn't protected. Their organisation doesn't do those kinds of things these days because they know they can't get away with it. In addition, if they follow city permit laws and assemble at designated times on public property or private property approved by the owner, they are also protected under freedom of assembly. \n\nSo yeah, they're pretty shitty, but they aren't illegal under current US legislation. ",
"Having and expressing beliefs of any sort is not illegal. Organizing with others with any sort of beliefs is not illegal. Why should these organizations not exist?\n\nAllow hate to be seen so it can be opposed.",
" > Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or **abridging the freedom of speech**, or of the press; or the **right of the people peaceably to assemble**, and to petition the Government for a redress of grievances.\n\nHow would you prevent them from meeting without violating the 1st amendment?"
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2jgze7 | what makes certain animals litter box-trainable and others not? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2jgze7/eli5_what_makes_certain_animals_litter/ | {
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"Some animals, particularly steal predators, have an instinct to leave their waste in the same, secluded area, often burying it, so as to not scare off prey.\n\nOthers want to spread their scent all over the place, so a predator doesn't have anything in particular to follow.",
"It all depends on how they evolved and how they would behave in nature.\n\nPoop is smelly, which can be either a good or a bad thing. Some animals, like cats, will naturally bury or hide their poop so that it will not let predators know where they are. Other animals will use the strong scent to mark their territory, and they will leave it around everywhere (or in certain locations). Some animals will pick a single spot to poop in (which can be also related to scent marking, or to keep their waste out of the rest of their living area.)\n\nMost animals that choose a particular spot to poop in, or that prefer a certain type of surface (like sand, for cats) can be litter trained. Since they take care to only go in a certain spot, you can reward them for going in the \"right\" spot, and they will remember it. Or, you can simply place the box where they naturally would go.\n\nAnimals that like to spread their poop around all over the place will be more difficult to train, for obvious reasons.\n\nAnd, still other animals don't seem to notice or care where they poop. Goats, for example, seem to have no concern whatsoever about where they go. These would be very difficult, or maybe impossible, to litter train."
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62cf6w | why do pornsites have so skechy advertisement? | Even on the big sites like pornhub or youporn you get popup ads, those stupid "Lisa close to you wants to fuck" (who does even believe them), make your dick bigger and WARNING YOU HAVE VIRUS ON YOUR COMPUTER.
Isn't it a bad rep for the site, annoying to customers etc? I understand they pay money but couldn't they get better ads that are not scams like sex toys or something.
Bonus question: Who the hell would like to share porn videos on facebook or twitter because there are banners for that? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/62cf6w/eli5_why_do_pornsites_have_so_skechy_advertisement/ | {
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"The reason for this is, \"normal\" advertisers do not want to be associated with porn. Which means these sites have to turn to other advertisers to generate revenue. ",
"Bonus answer: it doesn't come down to if you want to share porn on social media.\nIf your computer or phone is set up to automatically log in to different social media, it'll automatically log in once you visit a site that has a ' post/share on ______ ' as your credentials are stored locally on the computer/phone. That plus the Terms and Conditions of the social media that you've agreed to will allow data mining on the site that has the post/share function. ",
"IIRC someone who made these ads answered a question on Reddit once and said quite simply that it is because those ads are the ones that get clicked on. Somehow. ",
" > who does even believe them\n\nNever underestimate people's stupidity. I know too many people who have tried those things. And surprise surprise, none of the shit works. Having said that, they do send you physical stuff most of the time (I was honestly expecting it to be take your money and not even have products to ship).\n",
"* mainstream advertiser don't want to be associated with porn\n* people looking for porn are more likely to click a dodgy link to find some\n* people who get malware looking for porn are less likely to complain about it"
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5yo2qz | how do astronomers know the exact position of every planet at any time they want? | Suppose I am an astronomer and I will launch a probe to mars right now. In order to do my calculations, including the slingshot from earth I have to know where mars is right now and where it will be when the probe arrives. But how do I know the position right now?
Using a metaphor, if I want to adjust the clock of my computer I simply connect it to the web and it will get the time from a time server. In other words, someone has an atomic clock running somewhere that is accessible from the web and agrees with other atomic clocks around the globe. But what about the positions of every planet. Is there something that is accessible from the web that astronomers use to get the position information of planets? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/5yo2qz/eli5_how_do_astronomers_know_the_exact_position/ | {
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"Astronomers over long periods of time have visually pinpointed Mars' position in the sky. \n\nUsing lots of these observations and our knowledge about gravity and planetary orbits, they've been able to use math equations to describe Mars' orbit around the sun. There is an equation that describes Mars' position relative to the sun, and there is an equation that describes Mars' position relative to the earth. All you need is to define the variable of 'time' (just plug in a date) and those equations will tell you where Mars will be on that date.\n\nThese equations exist for all of the planets and many other celestial bodies. You can create an equation for any celestial body relative to any other celestial body if you have enough data."
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4o94j2 | why hasn't snapchat fixed the picture and video quality for android to match the quality on apple devices? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/4o94j2/eli5_why_hasnt_snapchat_fixed_the_picture_and/ | {
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"the problem is that there is not just one version of android. you have lollipop, and kitkat, and marshmellow each with different versions. Some phones will not upgrade to the newest software. be thankful that you don't own a windows phone that you can't even get snapchat on",
"I'm not sure if this has changed, but Snapchat 'takes' pictures by opening the camera and taking a screenshot of the preview feed. It's dumb and depends on the resolution of your screen rather than the actual sensor. It never really takes a picture in the same manner that your camera app or other apps would.\n\nI wouldn't know why the developers decided to do this though.",
"I can't tell you why they don't fix it, but I can explain the problem. On android devices, Snapchat never actually takes a picture. It just takes a screenshot of the preview shown on the screen (the preview obviously has worse quality than the pic by definition).\nOn Apple devices, Snapchat actually takes pictures, explaining the by far better quality.\nAgain, idk why they do it like they do, heard it does have something to do with avoiding to deal with all the (varying!) Android hardware that's out there and just simplifying the coding process.",
"These answers all get roughly half the answer but not all of it. On Android, Snapchat will just take a screenshot of the camera view. The reason isn't for 'compatibility' or 'iOS fanboyism'. No the reason is that way they can take a picture instantly. Not every device can handle taking a picture with no delay, and especially not with HDR+ and post processing which can sometimes take forever. So instead of potentially missing the moment for a better picture they take one instantly. Especially because WHO CARES about a marginally better look? Snapchat sends pictures with good enough quality, especially because you'll only see it for a few seconds and it's gone. The only problem with the different hardware is that some phones can't handle taking a picture quick enough, not that Snapchat would need to code in a billion different lines of code (this is true for almost everything in Android....almost all the hardware differences have APIs that abstract the differences out)."
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frdiua | how do cpus have such a high wattage and such a low voltage? | Most CPUs run at less than 2 volts, yet they pull more than 100 watts. Surely they don't have 50amps running through the tiny traces? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/frdiua/eli5_how_do_cpus_have_such_a_high_wattage_and/ | {
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"They have many, many traces.\n\nThe goal of low voltage is to reduce power consumption, it takes fewer electrons to charge up a gate to 2V than 3.3V.",
"yes, they do. They run at such a high speed that the transistors are always switching, and therefore they're pretty much always in their linear region and burning power. They tend to have upwards of 8 seperate power phases for high end CPUs. Look on the motherboard, near the CPU there's a bunch of massive inductors. each one is a power phase.",
"Not through each individual trace, but remember there are BILLIONS of transistors inside them and so there are a LOT of individual traces. Similarly many of the pins on the CPU are for power in/out and not just a single input and output.\n\nAlso the voltage is more like 1.3 volts. And yes, there is 77 amps (`100 / 1.3`) amps coming out of the VRM (voltage regulator modules) heading towards the CPU. It scatters around, but it's there.\n\nFinally that is supposed to be a worst case number. You'll hear the CPU get busy as the fans spin faster to cool the CPU. Most of the time it'll be much lower, and the voltage may even come down.",
"They have very large traces connecting to a huge amount of power and ground pins.\n\nAround the CPU you'll see a dozen capacitors and probably some square box inductors as well. These are the voltage regulators that step the CPU power down from 10A at 12V to 100A at 1.2V that the CPU needs to run.\n\nAll this will hop into a very large copper trace(generally called a plane or pour) to get to the CPU socket where it will then join up with the appropriate pins, and there are a lot of power and ground pins going to the processor. Intel LGA 1151 sockets have about 150 power pins and nearly 400 ground pins to carry all the current the processor needs\n\nOnce inside the chip there is going to be a thick amount of copper running around the chip serving as power and ground as all transistor sets need access to it. These tiny copper wires each carry a small amount of current, but a million copper wires each carrying 100 uA is 100A of current! This is why heatsinking is so important for a CPU, all the power that it uses gets turned into heat"
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35z47v | what is the difference between these two urls: "_url_1_" and "_url_0_x"? specifically, why would a website use one or the other for a new page? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/35z47v/eli5_what_is_the_difference_between_these_two/ | {
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"One is a subdomain, the other is a part of the main page of the website.\n\n_URL_4_ is the main domain. \n\n_URL_1_ is a subdomain, but still part of the main one. (Think of google then _URL_0_)\n\n_URL_2_x is another page from the main website. \n(_URL_3_)"
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d5m29w | how does a three wire three phase circuit work without a neutral? | I'm learning about three phase three wire circuits in class and I got a little confused. If you have a three phase source of 120V each 120 degrees out of phase, how does the current return? I thought all current needs some type of return wire? How can the current return when you only have three source wires? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/d5m29w/eli5_how_does_a_three_wire_three_phase_circuit/ | {
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"If you drew each phase on a single diagram, you will notice that at any point in time, at least one of the phases will be positive and at least one will be negative. Using electrical parlance, the positive phase(s) will source the current and the negative phase(s) will return (or sink) the current.",
"The neutral is only there to carry unbalanced loads(for example, a light bulb connected from one phase to neutral), with a balanced load there is little if any current on it(gets complicated when you consider low power factor). \n\nIf you connect three identical incandescent light bulbs in a Y configuration, there won't be any current on the neutral. When phase A is at maximum positive voltage, B and C will be at half that voltage, but negative. The return path for current will thus be split between phase B and C. \n\nIf the only thing you're running from a 3 phase circuit is 3 phase loads, like motors, it's relatively easy to get a balanced load. Only one phase crosses zero at a time, so the other two can act as current return paths for each other"
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106118 | why can't i have a fox or koala bear as a pet? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/106118/why_cant_i_have_a_fox_or_koala_bear_as_a_pet/ | {
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"In some countries, you can! But there are several reasons for why it would be illegal.\n\n1. An exotic pet that posses little immediate risk to human life can still get loose and cause damage to crops/wildlife.\n2. The animal is a protected species.\n3. It has been ruled that such an animal would not thrive as a pet.\n4. The animal posses a risk to humans.\n5. It would be unlikely that the general public would be able to properly care for that animal.\n6. The animal posses certain health risks.\n\nFun fact: With a lot of exotic/wild animals, you do sometimes have the option of applying for a license to own the animal legally.\n\nAlso, don't worry about foxes for too much longer. They are currently being domesticated with great success and in the future may be available for legal pet ownership.",
"Because they would bite you and pee all over your house. "
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bphqu8 | why and how do we get tongue blisters? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/bphqu8/eli5_why_and_how_do_we_get_tongue_blisters/ | {
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"It sounds like you may be referring to a canker sore. \n\n\nThe precise cause of canker sores remains unclear, though researchers suspect that a combination of factors contributes to outbreaks, even in the same person.\n\nPossible triggers for canker sores include:\n\n & #x200B;\n\n* A minor injury to your mouth from dental work, overzealous brushing, sports mishaps or an accidental cheek bite\n* Toothpastes and mouth rinses containing sodium lauryl sulfate\n* Food sensitivities, particularly to chocolate, coffee, strawberries, eggs, nuts, cheese, and spicy or acidic foods\n* A diet lacking in vitamin B-12, zinc, folate (folic acid) or iron\n* An allergic response to certain bacteria in your mouth\n* Helicobacter pylori, the same bacteria that cause peptic ulcers\n* Hormonal shifts during menstruation\n* Emotional stress\n\nCanker sores may also occur because of certain conditions and diseases, such as:\n\n & #x200B;\n\n* Celiac disease, a serious intestinal disorder caused by a sensitivity to gluten, a protein found in most grains\n* Inflammatory bowel diseases, such as Crohn's disease and ulcerative colitis\n* Behcet's disease, a rare disorder that causes inflammation throughout the body, including the mouth\n* A faulty immune system that attacks healthy cells in your mouth instead of pathogens, such as viruses and bacteria\n* HIV/AIDS, which suppresses the immune system"
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79madw | what is the meaning of "1.4" in "1.4 petrol engine"? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/79madw/eli5_what_is_the_meaning_of_14_in_14_petrol_engine/ | {
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"1.4 is the number of litres the cylinders have collectively, i.e. in a 4 piston 1.4 L engine each cylinder has a volume of 350 cc. \nHow it relates to power is that the larger the volume/cylinders, the larger the explosion in each cylinder so the more force generated in the engine. ",
"1.4 is the engine displacement. It's measured by the cylinder bore (width) and stroke (the difference in the farthest travel up and down in the cylinder). \n\nGrossly overgeneralizing, larger engine displacements will result in greater power production, while smaller naturally aspirated engines (not turbo or super charged) produce less. Can't speak for where you are located, but 1.4 L would be on the smaller end of engines here in the USA.\n\nEdit: a word",
"Nowadays, it's mostly marketing, but their meaning used to show engine displacement (i.e. swept volume of all the pistons inside the cylinders of a reciprocating engine in a single movement from top dead centre (TDC) to bottom dead centre (BDC)), specified in liters. \n\nSo 1.4 means the volume of the piston chamber that is where the explosion happens as the pistons move down is a total of 1400 cubic centimetres. \n\nHowever, these figures are usually rounded up, for multiple reasons, so you can have a 1211 cm^3 engine that is labeled as 1.3.\n\nHistorically, displacement meant more power, since there was more room for the explosion, thus a more powerful explosion could happen.\n\nFurthermore, displacement is far less important in modern engines that make a lot of power from less displacement, with significant fuel savings."
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8dtjjv | does our brain perceive and interpret subtitles on a screen we are not focused on? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/8dtjjv/eli5_does_our_brain_perceive_and_interpret/ | {
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"In my experience, kind of. But it's a learned skill. When the average person is watching a movie or TV show, their brain is purely focused on the visual. When people first start watching something with subtitles, they'll focus on the subtitles because their brain isn't trained to read and watch something simultaneously. Eventually you learn to split your attention, but you still have to focus on them to some degree. But you don't have to focus solely on the subtitles.\n\nAn interesting way around this is in The Shape of Water. In scenes where sign language is subtitled, the subtitles follow the focus of the scene, so as you're following what's happening onscreen you're automatically focusing on the subtitles.",
"Your question is a little confusing to me, do you mean subtitles on a single tv screen at the bottom or do you mean something altogether different?"
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6hadlb | why are pools cold in the middle of summer? | Shouldn't the water heat up in the sun if it's literally been open to the elements for months of hot sun? How is the pool still freezing, and not just the bottom of the pool, the top isn't even warm. What's the science behind this? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/6hadlb/eli5_why_are_pools_cold_in_the_middle_of_summer/ | {
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"Water has a lot of mass, simply put there's a lot of \"stuff\" there. With all that water to soak up the heat energy, it'll take a while to get hot. If you have two identical-sized spaces, one containing air and one containing water, and hit 'em with the same amount of sunlight, the air will \"feel warm\" long before the water will. \n\nAdditionally, it's easy for any absorbed heat energy to dissipate through the concrete and into the ground. \n\nAdditionallier, the pool has all night to dissipate heat.\n\nAdditionallilililier, because water's a good heat conductor, it'll pipe heat away from your hands better than air will, which makes your nerve cells go \"this is cold!\" even if the air and the water are the same temperature.",
"Because it gets cold again at night, and the ground around it is also cool. The sun does heat it, but the heat is lost very quickly to the cold air once the sun goes down. \n\nIn places where it doesn't get cold at night, pools can get really hot. In Phoenix, AZ, there are services that will bring ice to your pool to lower the temperature, because pools can reach the high 90s when the summer heat peaks. ",
"A few things -\n\nFor one, water heats up more slowly than the air, so all else being equal, the temperature of a pool will lag behind the changing season.\n\nSecond, the water is out warming up all day, but it's also cooling off all night. So it will never get quite as hot.\n\nFinally, it might *feel* cold, but it could well be the same temperature as the air. It's just that either way, it's cooler than your body, so you lose heat to 80 degree water faster than to 80 degree air.",
"Keep in mind that the ground doesn't get nearly as warm as the air (especially once you get a few feet into the soil). So the pool must warm a large amount of earth to maintain temperature. Next, for the night it's exposed to the [very cold night sky](_URL_0_). \n\nFinally, remember that your body is pretty terrible at measuring temperature, rather it's does a great job of measuring heat transfer away from you and calling that temperature. Water transfers more heat from you than air, so when air and water are the same temperature, the water will feel much, much further from your body's temperature (or in the case of the pool cooler). "
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8zcyzb | why do tires lose air pressure faster when the car isn’t being driven? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/8zcyzb/eli5_why_do_tires_lose_air_pressure_faster_when/ | {
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"I don't know for sure. But I'd assume its because when a tire under weight sitting in one position for extended periods of time, starts to deform slightly on the side thats touching the ground. Weakening the seal around the rim. (I'd also assume, the longer it sits and leaks the faster it deforms because it has less air to maintain its shape. And the more deformed the weaker the seal.)\n\nBut when its in use regularly its weight is always being distributed on different sides of the tire when moving and stopped. So it doesnt deform, causing the seal to leak as much as when its been sitting in one spot for a long time.\n\nBut again im not an expert, it just to make sense to me. I'd love to hear from someone who knows for sure though."
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93aohm | can someone explain dr. hawking's concept of "imaginary time" like i'm 5? what does it exactly mean in laymen's terms? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/93aohm/eli5_can_someone_explain_dr_hawkings_concept_of/ | {
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"Oh boy, this is a tough one to ELI5, but I'll try. Without getting into too much detail, the important part of general relativity is what is known as a metric tensor (the name is kinda intimidating, but try not to worry about it). Basically, this is the thing that gives you all of the information about your spacetime. However, the only difference between a space dimension and a time dimension is a negative sign (so the time term gets a negative and the space term gets a positive or vice versa depending on convention). It also turns out that, usually, these terms are all squared. So, if you multiply the time term by the square root of -1, you get back a space term. But the square root of -1 is an \"imaginary\" number, hence the name imaginary time.\n\nBut what's the point of it? Well there are a lot of thermodynamic implications of imaginary time, but I think you are more asking about the big bang type of deal. Essentially, what Hawking (and others with him) found is that, by considering imaginary time and using it with standard time, you can \"cap off\" certain types of universe. Basically, at early times, you can consider time to be imaginary and therefore act more like space. What this does is actually closes up the boundary of the spacetime so that it looks like it is all originating from one point. It gives you a big bang. This is known as a Hartle-Hawking state and has actually been a very valuable tool for understanding quantum gravity.",
"The namesake of Imaginary Time gives it more of a mystical meaning than I believe it is generally interpreted. \n\nIt results when solutions to certain kinds of problems are given where time is in the form of the square root of -1, or i - the so called “imaginary unit”. \n\nThese problems where imaginary time arrives are an artifact of particular kinds of approaches both in Quantum Mechanics, the study of subatomic particles, and of General Relativity, the description of gravity in the context of space and time, as well as the unification with QM with classical statistical mechanics / general thermodynamics. \n\nThis is all not to say that Imaginary Time does not have significant implications to physics. Most notably, it serves as a beautiful approach to justify the events before and after the Big Bang as explainable in the general geometry of spacetime. \n\ntl;dr: it’s a trick for physicists to connect different areas of physics and help explain events like the Bing Bang. \n\n",
"Normal numbers get bigger and positive when you square them.\nImaginary numbers get bigger and negative when you square them.\nTime is measured with these numbers. Moving in time contributes negatively to the Pythagorean theorem, moving in space contributes positively. Those numbers always add up to a constant, and the exchange rate between distance and time is the speed of light. Photons move 100% in space, and experience no time passing. We material objects move in space so little as to be unnoticeable, so we move (almost) entirely in time. When objects move at speeds closer to the speed of light, there is less interval available with which to experience the passage of time.\n\nedit: fixed an inaccuracy, I was tired. I'm glad this helped out some folks! IANAScientist, just a nerd, so I encourage you to research more on your own! This stuff is extremely cool, at least to me.",
"Okay, think about it this way. \n\nImagine that you want to specify exactly where and when something happened.\n\nSo, first you have to put it somewhere on earth:\n\nYou need longitude (how far East or West from a specific place)\nand latitude (how far North or South from a specific place). \n\nSo you have two separate measurements you need to take to put something at a particular place on the earth's surface. (also up-down, if you want to worry about being above sea level).\n\nFor time, we usually have only one line we worry about : Past-Future. \n\nWhat Hawking is saying is that in order to do certain kinds of physics, it might be useful to have a second line that *behaves like* our normal time-line, the Past-Future line, but is as distinct from it from it as the East-West line is from the North-South line.\n\nSo, just like the East-West and North-South lines are sort of similar in how we interact with them, but perpendicular to each other (but very different in behavior from the time-line) - the regular Past-Future line and the \"Imaginary Past-Imaginary Future\" line would be similar in the way they behave, but treated as \"perpendicular\" to each other in calculations. \n\nWhy \"imaginary\"? Because there's a kind of numbers called imaginary numbers, and you work with them by taking the normal number line, and putting another number line perpendicular to that, which is called the imaginary \"axis\" (another word for line). \n\nSo now you're probably wondering what it would \"feel like\" to deal with two different kinds of time ... at the same time. And there's no real answer to that, because we're only made to experience our one kind of time, and this \"imaginary time\" is mainly talked about to help understand certain physics calculations about the beginning of the universe - it's not something we could experience ourselves. ",
"A big problem when talking about imaginary time is the real-life definition of \"imaginary\", which gives the impression that imaginary time (and imaginary numbers) are \"made up\" or \"not part of reality\" in a way that non-imaginary time (and real numbers) are. This misunderstanding dates back to when someone first came up with a convention for taking the root of negative one, which was met with such derision that the resulting numbers got the epithet \"imaginary\". And we got stuck with it.\n\nAll that happened was that we found out that the result of a square root of a negative number wasn't in the old set of numbers. We then found out that if we defined a new number as equal to that value (_i_), we could manipulate combinations of that new number with the old numbers and we would have an entirely new set of numbers that all the old operations still work on. We made them up, but it's _really important_ to note here, _we didn't make them up in a way that was any different than how we made up all the rest of math up to that point_. The concept of zero is equally imaginary, we just calculate with it all the time, so we are comfortable with it.\n\nNow, back to imaginary time, it turns out that there are some ways of describing time that map them to some sets of numbers that, when multiplied by _i_, result in similar sets of numbers that also usefully describe time. The approaches are not ways you'd normally count time--they are specifically used to relate special relativity to other physics concepts--so there's no such thing as a \"clock to measure imaginary time\", or something. It's not an \"inverse time\" similar to dark matter, either--it is simply a way of describing time's behavior in a very specific context where this math is used.",
"Can anyone explain why squaring time gives negative? i.e. why is time placed in imaginary line?",
"Is this Imaginary time and Imaginary, complex numbers the same?",
"I think what I really really don't get with just about any physics question is time itself.\n\nWe invented it.\n\nEarly on, I suppose it was candles, sundials, and such. Now, we're look at radioactive decay and have atomic clocks.\n\nBut any/everything I know about time seems to derive from observation.\n\nWhy does relativity/point of reference not sort of tautologically 'destroy' the concept of time?\n\nWe don't really have any idea what our point of reference is, nor if it constantly changes.\n\n[Where's the center of the universe?] (_URL_0_)\n\nI read something like that and it says, oh there is no center because all of it expanded at once.\n\nHuh? However tiny it started, it had a center to begin with. Where'd it go?",
"We have some math that describes the world pretty well. But some people think you might be able to do things in the world that seem impossible using this math, by inputing negative numbers. So, something with negative mass might be repelled / \"pushed up\" by the earth's gravity instead of attracted / \"pulled down.\" Or we might be able to go \"back\" in time rather than forward. Or something like that.\n\nExcept that some of these numbers in this math use square roots, so that something like \"negative time\" doesn't actually make sense. Instead, if you try to put negative numbers in some places in the equation, you don't get negative numbers; you get the square root of a negative number.\n\nThere's one problem with this. There is no good answer to what the square root of negative number would be, since 2 * 2 = 4, but -2 * -2 also equals 4. So, instead, mathematicians designate the square root of -1 to be i, and multiples of i to be imaginary numbers.\n\nSo, what would it mean for there to be imaginary time? There's no good answer as to what that would even mean, outside of these equations. But it is allowed by these equations, given certain circumstances that just happen to never occur.",
"Time needs one number to describe a point in time.\n\nSpace needs three numbers to describe a point in space. \n\nSpace is three dimensional, forward-back, left-right & up-down\n\nTo make 4D space-time the timeline needs an extra dimension, just like a line needs a flat sheet of paper to be drawn on.\n\nMixing the 1D timeline with 3D space requires a second dimension of time. It as if the timeline were drawn on a 2D sheet of paper.\n\nThe second dimension is called imaginary time.\n\nImaginary means it is a numberline based on the square root of -1, called an imaginary number.\n\nImaginary numbers keep separate from normal numbers which is useful for a dimension.\n\nImaginary numbers have mathematical properties that allow rotation between the real and imaginary dimensions - just like a line can be rotated on a flat piece of paper.\n",
"Imma give this a shot. \n\nBefore talking about imaginary time we need to talk about imaginary numbers. They sound intimidating but they're ok. Let's look at them.\n\nWe're all familiar with \"real numbers\", these are the regular numbers like 4 or - 10 that we use every day to describe things, like temperature or how many eggs we have in a basket. \n\nBut real numbers are not the only kind of number. There's also a type of number called an \"imaginary number\". These guys get the symbol *i*. For example, we can have *i* or - 4*i*... And we can do pretty much every thing we can do with regular numbers with them, but not everything. The reason for this is that they represent a different kind of thing which behaves differently to real numbers. This is why we can have 5 apples but not 5*i* apples. It just doesn't make sense in the same way having a negative distance doesn't make sense.\n\nNow in the same way time can pass, ie. A glass may take 10 real seconds to fall from a table, you can also have imaginary time passing (I.e. 10*i* seconds) , but in the same way you can't have 5i apples you wouldn't use imaginary time to measure how long it takes for something to happen in the \"real\" world.\n\nHope this helps! ",
"the trouble with time, from what i've read, is that we experience it wrongly. we tend to think of time as a line that goes from left to right (past to future) and the present moment is a fizzy point (like a lit fuse) that is traveling along that time line.\n\nbut time is not like that. we experience the past and we anticipate the future, but that is a function of how we have learned to process time. (some cultures don't see time as a line that travels left to right, they see it as traveling from east to west...like the sun. so we don't even all process it the same way). not to get all \"alan watts\" with this, but technically, there is no such thing as the future. it does not exist at all. in our experience *something* will happen in the next moment, but we'll never know what that is for *sure*, and so, according to watts, there is nothing. \n\nas i understand it, time is basically the measure of entropy and is subject to the forces of gravity. it doesn't travel neatly along a line.\n\ni only say all of that to respond to the question of the OP. if someone is to answer the question, they also need to be clear about what time actually is. in a very philosophical way, all of time is \"imaginary.\" the past is not a thing...(it's highly subject to errors), and the future is non-existent. we barely know what the \"now\" is since our brains actually process things a few milliseconds after the fact...so we are, in a way, constantly experiencing the now from in the past.\n\nso maybe the first step is for someone here to help us understand what we're talking about when we're talking about \"time,\" imaginary time notwithstanding."
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4n7liw | i recently sliced the tip off of my finger. why are my neighboring fingers now sore / more sensitive? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/4n7liw/eli5_i_recently_sliced_the_tip_off_of_my_finger/ | {
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"I've had similar sensations in the past. A Doctor friend explained it to me as your brain just sort of cross-firing the pain response. From the standpoint of evolution, it could your body's way of saying, \"Hey, Klutz, you're hurting yourself, how about we just slow things down a bit?\"\n\nIt's nothing and should pass. If, on the other hand, it isn't nothing and doesn't pass, enjoy the short time you have left, or, your super powers. Whichever comes first.",
"Curious. Could it be related to the phantom limb syndrome that amputee's fee? ",
"Maybe inflammation has spread a bit?\n\nBefore fixing my diet I had gut issues - and the inflammation would often spread to my back muscles and gave me issues there as well.",
"Bear with me:\n\n > A major nerve in my arm was severed in a car accident. As a result, I cannot move my pinky or ring finger on the hand at the end of that arm.\n\n > But I also cannot \"clamp down\" the thumb on that hand in certain ways. I can move the thumb around anywhere I want, but I have to hold things in my hand a certain way if I want my thumb to hold on to them. I just cannot apply much force with my thumb in certain directions.\n\n > The same goes for the entire arm. If you've ever lifted a heavy weight over your head, you may have noticed that there's a point half-way up where it's natural to pause and gather your will together before lifting the weight further. If you can picture a professional weightlifter in a competition, you can see where they pause.\n\n > A gym teacher told me once that this is because lifting the weight further relies on a different muscle group. Lifting the weight over your head is two separate actions.\n\n > I can't do that second part very well with that arm. I can lift that arm all the way up, but I can't lift much weight with that arm above that muscle-switching point.\n\n > The point of all this is that the nerves running through everyone's bodies -- including my arm -- are cross-wired in funny ways. The severed nerve affects my two smallest fingers, and then the one on the other end of the hand. The two fingers between work fine, as does my lower arm. But my forearm is impaired.\n\n > Even stranger, though I can move my thumb and forearm any way I want, I cannot move them with strength in certain directions. This is because the non-damaged nerves in my arm have connections to all the muscle groups in my thumb and forearm, but most of the connections to certain muscle groups ran through the damaged nerve.\n\nTL;DR/ELI5: Your nerves aren't wired like the wiring in your house or a map of the Internet Backbone. There're a lot of cross-connections and they're not all created equal. If one finger is reporting \"PAIN OMG DAMAGE REPORT AVOID DEFEND\", your brain will see that message from every nerve \"ringing on that line\" -- and there are a small number of nerves in your other fingers on that circuit (this is \"referred pain\").\n\nThey are reporting -- falsely, as it turns out -- the need for increased defense, i.e. sensitivity. The more \"mainstream\" nerves connected to those digits don't see the problem.\n\nYour confusion is entirely natural; you're getting two different messages."
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3wpvg8 | my local mcdonald's charges $1.07 for a large water and only $1.00 for a large sweet tea. why is this an economical decision for mcdonald's? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/3wpvg8/eli5_my_local_mcdonalds_charges_107_for_a_large/ | {
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" I haven't been to McDonald's in quite a while, but I assume the sweet tea is something that comes in a beverage cup, is made with local tap water and they just add some sort of sugar or mixer that costs them a very small amout, while the water was filled in a bottle at a plant and trucked to your location. If you ask them to fill a cup of water from their faucet, they will do it for free, it's the law. ",
"You will need to be more specific. Here in Texas they are not legally allowed to charge for tap water, which would be the kind that goes into their tea. But they can charge for bottled water which would have its price set by what it costs them to get it. So my automatic response is that you got a bottled water. If you did not then they either made a mistake and charged you for a bottled water, illegally charged you for water, or you live in a region that they can charge you for water. ",
"Where does McDonalds charge for water? Do you mean a bottled water or a fountain water? Most places in the US provide fountain water for free.",
"This has nothing to do with profit margins. They don't want you to drink water, because water isn't bringing you back again in the future. Sugar loaded sweet tea is. \n\nUsually the $1.00 large drink is part of a marketing promotion designed to bring customers in the door, where they will be sold food with their $1.00 drink. At $1.00, the drink is meaningless to them, they are going to make their money from food orders. It costs them like $0.05-$0.10 whether you want a water or sweet tea. That extra 2 cents isn't going to matter to them. \n\nYou are looking at the situation the wrong way.",
"They don't want you to sit there and just drink water taking up space? Addictive stuff will keep u fat and coming back",
"Large sweet tea for a dollar is a promotion. It's like the five dollar twenty nuggets. Depending on where you are and who the gm is at the store you were at, water is free or they charge. Source: worked at mcds for 2 and a half years.\n\nAt my store a large sweet tea is the same as a large soft drink. Water is free no matter the size if you buy something else, small waters are always free.",
"The sweet tea is advertised as only a dollar but comes out to $1.07 after tax. Ask for a small ice water and it'll be free. Any large drink regardless of what it contains will cost $1.07. \n\nSource: first job was at McDonalds",
"My guess is that they keep track of drink sales by cup consumption. Like yours, my local McD's has a different prices for iced tea and soda. They also have different cups - styrofoam for iced tea, and a waxed paper cup for soda. I guess also in self-service drink stores it helps them keep an eye on who's paying for iced tea but drinking the soda.",
"It's because you wanted a large.\n\nJust order water and it's free and a very small cup.\n\nYou're paying for the cup.",
"Tea a good deal, but how often do you get just tea? ",
"On mobile so I won't be posting sources unless less you ask. But having a sugary drink makes you eat more than if you didn't have the sugary drink. So their sweet tea should theoretically bring in more money (customer buys more food) than just plain water. Also sugar AND caffeine can be addictive separately. Having both in one drink? That's how they can try to hook you into coming back for more. \n\n\nEdit: Changed Subaru to sugary. ",
"Here's my guess. I used to work at a corporate McDonald's, and even large water in a styrofoam cup was free. You are probably going to a franchised McDonald's, not a corporate McDonald's. Back when water in a large cup was free at your McDonald's, someone was consistently coming through the drive-thru and getting water in a large cup. Some manager at the restaurant got really pissed off about it and changed the policy so that it cost $1.07. As other people have pointed out, they're probably still legally obligated to provide tap water in a small cup if you ask.",
"Why not just ask for a small water cup? Then it's free.",
"You didn't buy a water, you bought any drink they offer.\nYou can get any drink for $1 in a large cup, you bought a large cup and choose water.",
"In my state, tea isn't taxed. Perhaps that's the case here and not some weird financial decision?",
"I have a similar question (in Australia). We have Dinner Boxes (2 big macs, 2 cheeseburgers, 6 pack nuggets with sauce, 2 large drinks, 2 small drinks and 4 medium chips). Now, if i were to purchase a large normal coke, it would cost me about $2. While a frozen coke would cost me $1. However, if i want to change the 2 large cokes in the dinner box to a 2 frozen cokes (essentially costing $2 less, $1 less per drink) it increases the cost of the dinner box by $2. How does that work?",
"Do you seriously have to pay for a glass/cup of water where you live? Tap water is free everywhere here in Sweden.",
"I work at McDonalds (Canada)\n\nInterestingly, when you buy a carbonated drink the total with tax comes to 1.13\n\nA non carbonated drink such as ice tea or fruitopia comes to 1.05\n\nA cup you fill yourself is also 1.13\n\nMy guess is either a) the system was wonky (these things get overlooked so often on our tills)\nB) she read one with tax and one without\nC) there's some sort of deal they have with the sweet tea company \n\nWe don't even sell anything but small water on our drive thru, but its free. This is because we sell 751 ml bottled water for 1.99.\n\nAnyways, its all a bit flukey so I'd say there is nothing going on her but a mistake, not a decision made by the company.",
"So...based on some previous work, I can tell you that McD's more than likely has national/local volume incentives and/or rebates on what goes through their fountain. \n\nThese numbers obviously go up every year as their prior year numbers continue to increase, so it makes sense for them to offer it cheaper. \n\nFor example, they sold 1,000,000 gallons last year and Luzianne tells them, \"if you sell 1,100,000 gallons this year, we'll rebate you $1 per gallon”\n\nIf they only pay on \"growth cases\" it'd be an additional $100,000, but most often the rebates go back to the first case/gallon, so it could be an extra $1,100,000. \n\nThis is just an example, but should give a pretty good idea of why they offer it so cheap.",
"If it hasn't been said yet, some businesses use remaining cups as a way to inventory and measure sales of various sized beverages and somehow perform an auditing measurement of cup use and cash in the register.\n\nSo, it forces the staff to charge per cup size, no matter what was put into the cup.",
"This is just a guess as to why there may not be a discount to the price of a large cup of water. Water, as you mentioned, is flavourless and something you can get anywhere. Their sweet tea is a speciality of their company. This is encouraging you to try it, and hopefully hook you enough to continue visiting and purchase more in the future. \n\n",
"I work at McDonalds and we charge 25 cents for a large water just for the cup, any other water is free.",
"Sounds like they rung up a large drink for 1.00 and the sales tax added the .07 cents, same would happen for the sweet tea, it's 1.00 before sales tax. Most mcdonalds only charge .27 or so (the price of an extra sauce pack) for a large water, some give all water sizes free. ",
"Short answer: The 7 cents is a tax, usually included in the dollar even when ordering with other items.\n However upsizing a water disassociates it with the rest and for some reason as a solo item is charged as a dollar plus tax.\n\nI was a manager at Mcdonald's until recently. There is an ongoing promotion where drinks are a $1 at Mcdonalds. Usually drinks that are not water are grouped with a food item and are charged a dollar even (doesn't mention tax on the screen but assumedly tax included on the dollar even price)\n\nAlso, ordering a sweet tea by itself can produce a $1.07 total\n\n water is free unless you ask for a larger size and for some reason is a dollar then the 7 cents (or more) tax\n\nThis is not a marketing gimmick, just the system automatically attaches it to a meal and has tax included in the dollar even price, or there is an upsizing seen as a special command and the water becomes a solo meal item where for some reason tax is not included in the dollar.\n\nthat was redundant!!",
"The tea is actually most likely cheaper.\n\nThe tea probably comes out of a soda fountain or tea urn. If from a soda fountain, it's hooked up to a water pipe. When you hit the button to dispense tea, it shoots water through the fountain and mixes it with a very, very concentrated flavoring syrup, making it taste like sweet tea. The amount of syrup it takes to flavor a 16oz cup is next to nothing. For instance, you can buy a 3 gallon container of sweet tea syrup from Sam's Club for [under $40.00](_URL_0_). For comparison, a 1 gallon syrup container of soda runs around $70.00. Most soda fountains mix water (or carbonated water) and syrup at a 5:1 ratio. So a little math gives us a basic profit yield. \n\n3 gallons is 384 ounces. Now, since the dillution rate is 5:1, a 3 gallon bag of syrup will give you 1,920 ounces of sweet tea.\n\nYou said you bought a large sweet tea for $1. In the US, a large cup at McDonald's is 30oz (holy fuck that's a lot, by the way). That's 64 large sweet tea portions (without compensating for the dilution from ice, for which you can estimate about 25% of the total container volume is taken up by ice) at $1.00 each, so $64 gross income from 3 gallons of sweet tea syrup. Earlier, I said that you can get sweet tea syrup for under $40.00 from Sam's Club. Now, mind you, McDonald's pays much, much, much less for theirs. Because they buy such huge amounts of it, their vendor (assuming McDonald's doesn't just make the syrup themselves, which they probably do) is likely around $20 or less. \n\nThe water also comes out of the fountain, but is affected by other costs. The water out of the fountain is the same water in the ice, in the sinks, in the bathrooms, from the hose. Every single thing in that restaurant that uses water all comes from the same place, the pipes under the store. Now, without looking at their monthly utility bill, I can't be sure how much water the average McDonald's store uses in a day, so I can't do a cost breakdown, but they most likely make more profit on the sweet tea (or soda) sales than they do on the sale of water.\n\n",
"Here in Wisconsin, the large is $0.50 (not including tax), and the small is free. I believe that may be due to the cost of plastics in the area, or your local store having an upcharge for some reason\n\nSource: I work at a McDonalds",
"The bigger question is: Why is it $1.00 for a sweet tea and $1.20 for unsweet tea!? ",
"In my country in Colorado, not all items for sale are subject to sales tax. From what I can surmise as a layperson is that food items which are considered to be very basic and necessary are not subject to tax. Included in this appears to be things like milk (even small individual serving bottles), bottled water, etc. Prepared beverages, however, are definitely taxable. \n\nI think your large tea has the same base price as the large water, but only the tea is taxable. ",
"Do they have the fountains outside in the lobby? If that's the case, the price is probably to deter sneaky hoodlums from getting a free large cup for water and then sneaking soda out of the machine when they're not looking. ",
"Too many folk asking for cups for water then getting soda with it instead. So they are charging you for the cup not the water.",
"Ok so I'm in New Zealand, and this may not apply, but when you get water in a cup here at Maccas, they have to walk to a different area(usually the mccafe part) to pour the water.. now the water is free because it has to be due to NZ law, but maybe that time it takes to go to the tap instead of the fountain right behind them is what they are charging the 7c for? ",
"They charged you $1.07 for tap water? That's shitty. It's illegal to charge for tap water in the UK ",
"OT but a nice water story from my hometown.\n[Captains Well](_URL_0_)",
"Yeah at the one I used to work at we always just rung up water as sweet tea because of this",
"A cup of water is free but there's a specific size cup associated with free water. If you deviate to a larger size then they'll charge you. Not all chains do this but most do I think.",
"I've never heard of McDonalds charging for water. However you usually can't get a large water, you'll get a medium cup.",
"They also charge 4.45$ for 10 nuggets and only 5$ for 20 nuggets. Furthermore, 20$ for 50 nuggets. Logic is not a priority for them. ",
"Ever notice that the McDouble is 30 cents cheaper (in Canada at least) than a cheeseburger even though a McDouble is just a cheese burger with an extra patty? ",
" > 1.07\n\nIf I had to guess, I would say that the goal is to make you fiddle with small change a lot. :-P",
"Part of big phrama, its cheaper to buy sugar loaded items at first but when you need medication for diabetes thats when the money rolls in. \n ",
"If you're willing to spend X amount already, you're more likely to spend more money on something that's \"better\" than water. Like a Coke. ",
"I dunno but my mcdonalds will allow me to fill my 2gallon camel with sweet tea for the $1. Nice for long rides lol",
"This probably has to do with an economics concept called price elasticity.\n\nProducts range from being perfectly inelastic to perfectly elastic, and mostly fall somewhere in between.\n\nLet me give a simple example regarding the water, which is probably quite inelastic.\n\nLet's say you were at McDonald's, and you wanted a water. Most people get a water instead of an actual drink because they really, really want a water. Either they're really thirsty, or they're on a diet. In either case, a water is significantly superior to anything else on the menu.\n\nIf I really wanted a water, I wouldn't care if it costed 10 cents or a dollar; both are within what I can afford. Now, I might get outraged if it cost 10 bucks, enough that I'd storm out of the restaurant and go somewhere else with cheaper water. Or more likely, I'd just call them on their BS and buy a bottled water for $2 or whatever.\n\nMcDonald's is a smart corporation. They probably did extensive analysis, and found that they maximize profits by selling the large water at that price. If they sold it for a higher price, there would be a large drop off in number of buyers, which results in less profits overall.\n\nRemember that revenue = price * quantity sold. So number of buyers matters (a lot). If they can sell water at $1.07 to 100 people per day, that's probably better than selling it for $1.57 to 50 people per day, even taking into account the cost of the sale.\n\nFor the tea, we have a product that is probably far more elastic. There are many more substitutes for the sweet tea on the menu. If we think it's too expensive, we could get a coke, or a sprite, or a lemonade or whatever. Heck, we could even decide that it's fattening and get a water instead. :)\n\nThis is why McDonald's can't charge that much for a sweet tea. Not because it's not worth more than the water, but because selling it for more would not be profit maximizing. Less people would buy it, which would result in lower revenues.\n\nOf course, this is a very very simplistic explanation with many issues , so take it with a grain of salt.\n\nTL;DR: Charging a price that maximizes the profits for an individual sale is not the same as charging a price that is profit maximizing overall.",
"I'm a McDonald's employee who has a bit of knowledge about how some of the company is ran. The big thing to remember is each store can have completely different pricing. There are 6 within a 20 minute drive of where I live. Of those 6 there are 3 that have different prices for different foods and drinks. It's largely a mix of whether or not the store is Owner-Operated or a corporate store. Also it will have to do with state laws, city laws, random tax changes, and just general location.",
"I asked for a cup of tap water in McDonalds once \"We can't do that\" they said\n\nYeah I'm sure your drinks fountains use fucking vichy water and out of the faucets comes the piss of angels.\n\nEnded up giving me hot water with ice for free. What?",
"In some eastern European countries, beer is cheaper than water.\nIn your case maybe the icetea was manufactured in a state where water + ingredients is significantly cheaper so when it gets here could be cheaper then just using tap water.",
"$1.07 is the cost of the LARGE CUP. You can use the Large Cup to Refill ANY Drinks not just water.",
"In my opinion it is based on their insight into the buyer. Individuals who are purchasing bottled water instead of the soda earn more and will pay - McD’s can get away with charging that demo the higher price. Consumers of sugary drinks tend to be less well off socio-economically speaking and are less tolerant to high prices.",
"McDonalds manager here. The reason you're getting charged $1.07 is because you're getting charged for the drink ($1.00) and tax. Really you're just being charged for the cup. A sweet tea is $1.07 as wel after tax.\n\nWhy they are charging you at all though is pretty strange. Their food cost must be incredibly bad or just their sales in general if they charge for large water. I've work at 4 stores and none have done that. \n\nThey should be charging you you only a dollar as water shouldn't have the .07 sugar tax on this if they were going to charge you. They shouldn't be charging you at all though. The amount of money their losing on giving free water is completely unimportant and so incredibly low.",
"I would suspect that the water charge is to discourage people coming in for free water while the sweet tea is a loss leader. You come in for tea and something else.",
"It sounds like they made a mistake to me. Normally they give free \"courtesy water.\"\n\nIt might be because you asked for it in a large cup. That might just be the price for any drink in a large cup. Tea usually has some sort of \"any size for a dollar!\" promotion. They should not have charged you for tap water though.\n\nThe profit margins on drinks at fast food restaurants are so big that they are making a huge profit no matter what they charge you. My first job was in fast food and my manager showed me the math for a few of the products. It only costs the corporation about 8 cents to sell you a drink. That includes labor and the cup actually costs more than the liquid inside does. ",
"Caffein is a diarrhetic. That means it flushes water from your system. They charge extra for the water because water will actually quench your thirst while the caffein in the tea will cause you to become more thirsty. The chances of you coming back for more are then higher. This is assuming you don't get free refills, you don't refill it yourself, or you ordered at a drivethru. So you coming back would mean you paying more for another drink. Otherwise, I can't imagine why the name of the drink you ordered would matter because if you were filling it up yourself, you would just ask for a large drink and just leave it at that..",
"It's economical because people, who would mostly buy the tea anyways, will now feel that they are getting a deal one the tea and be even more likely to buy the tea",
"Man, McDonalds just makes no sense sometimes. For example, a Sausage McMuffin costs $1.00. \n\nIf you want just a sausage patty, say to have an extra one with your hotcakes, it's $1.19. \n\nI will literally order a Sausage McMuffin minus cheese, minus muffin to get my extra patty. ",
"Tea has not been charged tax since a little tea party we held at Boston Harbor. That's why it works out that way -- .99 cents + tax on the water, $1.00 even for the tea with no tax. ",
"youre lucky it wasn't brawndo. It's the thirst quencher that plants crave because of electrolites",
"For McDonald's, the Sweet Tea is called a \"loss leader.\" It is a product that McDonald's has already accepted that it will not make a profit on. However, despite this product being sold below market price, it stimulates the sales of other profitable items. It essentially draws the customer in, a $1 dollar sweet tea sounds incredibly appealing (partly due to its cheapness) so you go to the restaurant, buy one, and inevitably buy other things that are profitable for McDonald's. It is a form of marketing built right into their menu. Water on the other hand is not going to bring as many people into the store. So they do not care about discounting it and it is more than likely priced at market value. Another explanation for water's price is they want to discourage sales of water and make you buy soda (more profit). People are extremely reluctant to pay for water, so the price tag may be an effort to dissuade water purchases. As another user said, water is not going to make a repeat customer, but addictive sugary beverages will.",
"Come to Australia. $3.80 for water I think? Large \"Big\" Mac meal is like $9.50.\n\nPay a dollar more and get a huge delicious plate of food from a local cafe and their chef.\n\nFor some reason people still go to McDonalds. Not many, but some.",
"\"If like a large water\" actually means \"I'd like a free large cup that I can put (enter random pop selection here) in\". They can't legally charge for the little cup but they can charge extra for those idiots who think they're getting away with a cheaper drink.",
"The tea is a promo for the restaurant but the $1.07 for water is to probably cover the cost of the cup they gave you. Or the clerk was dumb and charged you.",
"It's called a \"Loss Leader\". Fast food restaurants use them to encourage business. You walk in for the $1 iced tea, then once you're inside you can't resist the Big Mac or a super sized order of fries. The restaurant is willing to offer a popular item for cheap just to get you in the door.",
"My local McDonald's started to charge even for small water with the purchase of food... I got mad and made sure I complained. They sent like $20 in coupons however I don't want their coupons I just my little small free water that cost them $0.05 max after spending $5-8 every time... \n\nI could fully understand wanting charge if I just walked in there not getting anything else or wanting the largest cup there is.",
"The large plastic fountain drink cups cost McDonald's more than the foam cups that come with the Sweet Tea.\n\nSource: Manager of 7 years.\n\nEDIT: To add to that, most McDonald's don't charge up to a large, because the child, small, and medium cups are all cheap paper cups.",
"Reps for soda companies push restaurants to push soda over water. Drinking is seen as a habit. The more often people drink their product the more often that person will tend to opt for that product again rather than water. I don't know if this is what's going on at the location you're talking about but it is common in the industry so it wouldn't surprise me if there was a deal to make the cup water comes in more expensive than just ordering flavour sugar water of the same size.",
"The cost of making a product has no relation to it's value!*\n\nI spend a week digging a wonderful, fantastic hole. Want to buy it for a weeks worth of labor (~$600). Will it be worth twice as much if I keep digging for another week?\n\n*cost will affect how many will be made at a given price, but not the price itself.\n",
"Remember that the price that a business charges for a widget is not based solely on the company's cost to put that widget in your hands. It's actually driven far more by *what you're willing to pay* for that widget, or more specifically what the market is willing to pay.",
"Strange laws there. Our McDonald's (unless laws have changed and I'm not aware) cannot charge for water even if it is in a cup. They have to give it away for free.\n\nI wonder if it's actually legal there?",
"That's weird, I asked for water a few times and never got charged for it large cup small cup don't matter ",
"When I order a bottled water with my combo, I get a 50 cent upcharge vs a regular soda. Insane.",
"My local gas station charges $1.67 for a gallon of gasoline, but $1.99 for 20 oz. (16% of one gallon) of bottled water. It's sort of ridiculous.",
"Haven't been to McDonald's in years but if I went to a restaurant/dinner/eating facility and was charged for a cup of water I would just laugh and leave. ",
"No tax on tea? Anyone no of this beingtrue",
"I'm so surprised by how many people are trying to logic or math the shit out of this. No tax on tea cuz fuck that shit in America!",
"At my local McDonalds the tap water is free. You can get a large water for free, but if you want a bottle of water it costs more. ",
"I think the right answer is probably that tea would also be 1.07 after tax. But if you really want your head to explode - I was there at breakfast once and ordered the pancakes with sausage. I asked how much for an extra sausage patty and it was 1.50. So I said, no thanks. Give me the sausage biscuit from the dollar menu. Hold the biscuit. Voila! Extra sausage patty for 1.00 instead.",
"I would bet $1 that some MBAs studied buying patterns and found tea drinkers spent more than water buyers. They get a little break because more will be spent in total. \n\n",
"Marx taught that commodities had ideological dimensions. Your starbucks coffee is more than beans and hot water, it's a eucharist of leftist values. Your buying a water at McDonald's is more than hydration, it's an opportunity to pay to feel good about a decision.",
"You don't go there for the beverage you go for the burgers, so what they charge for water vs. pop has no influence on your decision to go there. \n\nIt's like a movie theater, if you were making the decision to use them based on the price of popcorn, popcorn would be fairly priced, you don't so it's not. ",
"Simple. Water is a healthy choice. They want people to be unhealthy so they encourage people to drink sugar water by making the price lower. ",
"Kind of Relevant...My daughter likes sausage patties in the morning from MCD's. They are $1.19. So I typically just buy a Sausage Biscuit for $1.00, and just take off the bread. IDK why that makes sense.",
"Are you in Georgia? If so that's just tax and they don't charge tax on prepared beverages I think.",
"At the McDonald's I worked at for several years (I'm sure at any McDonaldl's, actually) there was a problem with people getting a free cup for water and actually walking away and getting soda. My guess would be it is a defensive move to charge for a large water because they assume you will just be stealing soda anyway. The McDonald's I worked at in NY just refused to give out large cups for water, instead filling it up for you behind the counter so there'd be no need to walk over to the beverage machine. ",
"I used to work at mcdonalds. The person behind the register was too stupid to put in \"Large Water\" most likely, because whenever I did it it would come up as 10 cents.",
"If you buy a large cup, you're not buying the beverage, you're buying the cup.\n\nThe small water cup is free.",
"I thought it was a legal requirement to free water?",
"Are they allowed to charge for water where you are? Here in Ohio businesses aren't allowed to do that. tap water is free",
"It's probably as simple as them not wanting you to use their large cups for water when you could use small cups, so they charge more so demand goes down. I'm sure there are a ton of people who will opt for the small cup once they find out you have to pay (any price) for a large one. ",
"Supply and demand. You will find quite often with food/beverages that the price charged has much more to do with what people are willing to pay for a product than what is costs the company to supply the product. \n\nDo you notice how Mc Donalnds always asks \"would you like fries with that?\", its because the profit margin or fries is huge! "
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||
2st45t | how did antonio banderas' acting career go down the toilet? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2st45t/eli5_how_did_antonio_banderas_acting_career_go/ | {
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"text": [
"He's Puss in Boots...he's set. I wish my career was in that toilet.",
"Some actors are like fads, he went out of style in Hollywood.",
"I think he's just working in less now. He made that sweet Puss in Boots money so now he only does projects he's really drawn to. Check out Haywire and The Skin I Live In. 2 awesome movies he's been in in the last few years. ",
"I dont think his career went down the toilet. He made a ton of money from Puss in Boots and can now afford to only do stuff he is actually interested in, even if that will not a huge commercial success.\n\n",
"\"Automata\" now on Netflix. He is good in this one. 💀"
]
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||
2ponkp | if i have a dream in which i'm being shot, stabbed, or otherwise physically attacked, why do i feel a sensation in my body as if it's actually happening to me? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2ponkp/eli5_if_i_have_a_dream_in_which_im_being_shot/ | {
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"cmykq1w",
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"text": [
"Dreaming is an altered state of consciousness so your brain perceives the dream as real, hence why they're realistic. ",
"Pain isn't caused by being hurt, its caused by signals being sent to the brain. I suppose if you think its happening the warning signals are still sent.",
"The simplest answer to this is because it *is* happening to you.\n\nWhat you have to remember is that you are not actually a body: you are, at best, a brain driving around a mecha-suit made of meat and bone. Philosophically speaking, you might even be some other spiritual-type substance driving around a brain, but let's not get into that.\n\nWhen you feel pain, or pleasure, or perceive any kind of sensation, nerve impulses are traveling from your body up to your brain and relaying information that is (hopefully) about the objective outside world, like Jarvis telling Tony Stark that we're at 19% power and need to finish fighting this bad guy quick or we're going to die. \n\nThe upshot of this is that \"you\" (i.e. the brain in your head) can only know the information that is presented to it by the senses in your body. Now, we all tend to work off the assumption that the information we receive from the outside is accurate and objective, but sometimes it isn't: amputees feel phantom limbs, schizophrenics see and hear things that aren't really there, and even totally healthy people get weird signals from time to time (all you have to do to experience this yourself is get really tired, or really drunk, or hopped up on pain pills, and your interpretation of the outside world will start to drift from true north).\n\nSo when you're dreaming, your brain has no way of knowing that what it's seeing (and feeling!) isn't real. The signals may all originate in the brain itself (because of Freudianism or messages from the beyond or bad Chinese food before bedtime, take your pick), but \"you\" interpret the information you have on a good-faith basis. Your mind makes it real, just like in The Matrix.\n\nTL;DR - You are a brain, and there is no difference between real sensations and fake sensations."
]
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||
80f7vu | why can some feelings, like being hungry or tired, get progressively worse but after enough time has passed without eating or sleeping your body no longer feels as bad as it did before? | There's usually a slum when i have to pull an all nighter where I'm tired as hell, but if i fight off the sleep and stay awake, i return to my usual alert state, and even when it's time to go to bed and I've been up for 30 hours i can't seem to fall asleep.
Same for eating. If i don't eat for a while after i felt hungry i just don't feel hungry anymore until i realize i haven't eaten in like 2 days. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/80f7vu/eli5_why_can_some_feelings_like_being_hungry_or/ | {
"a_id": [
"duv5sd2"
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"score": [
5
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"text": [
"Because your body assumes that you're staying up late/not eating for an important reason and so adapts.\n\nHaven't slept in awhile? Your body thinks \"Well I must be awake because I need to in order to survive\" and gives you what people call a \"second wind\". This keeps you alert and focused so that you can do whatever it is that you need to do. It doesn't last forever though, and you'll eventually conk out.\n\nSame with going hungry. If you're hungry and don't eat for awhile, your metabolism will slow and your body will start burning off reserves instead."
]
} | [] | [] | [
[]
] |
|
3g7fzv | how does a locksmith create a new key if you have lost or locked your key in a vehicle? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/3g7fzv/eli5_how_does_a_locksmith_create_a_new_key_if_you/ | {
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"ctvl1vc",
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"text": [
"There are only limited versions of any given key shape for each model of car. A locksmith or car dealer can use the V.I.N. of your car, and get the specific key shape for your car from the manufacturers database. This is the same for electronicaly coded keys",
"They usually don't. \n\nThey will usually find an alternate way into your vehicle or house. This may take the form of exploiting a vulnerability using established tools, or outright destroying the lock. You're basically paying someone to break into your house or car. \n\nNow as /u/andyblu mentions, modern cars have coded keys and you actually need the code to get a new key made, so perhaps that method is available, too (but I'm not sure a run-of-the-mill locksmith can quickly and easily make a key based on a VIN). Usually when you call a locksmith it's because you're in a hurry. ",
"On some vehicles you can do what I used to call scratching. Basically you insert a blank key for the particular model of car into one of the locks. Wiggle it back and forth and take it out. Wherever you see scratches, cut a notch. Repeat this process several times, stopping where the wafer no longer scratches the key, and going progressively deeper in the positions that are still getting scratched. Probably doesn't work for ignition keys on newer models, but I've been out of lock smithing for about 10 years"
]
} | [] | [] | [
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