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5pt788 | Why is it often difficult to stay awake while reading, but as soon as you put the book down and try to sleep, you feel wide awake? | Other | explainlikeimfive | {
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"Actually, reading can be the *opposite* of stimulating! And that isn't shade. When you read, you're (hopefully) focusing on only one thing: the book. You're laying down in bed, you're comfortable and relaxed, your body is ready for sleep. When you put your book down, your thoughts don't have the 'filter' that focused reading brings. If you have any anxious or stressed thoughts creeping back in, you are amping yourself back up again and you'll have to calm down all over again before you can sleep. ETA: if you're reading off a screen, the blue light can mess up melatonin production, which impacts sleep."
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5ptdmg | What is the purpose of the turnable dial around the face of a watch? | Technology | explainlikeimfive | {
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"The ring as we know it today on some watches, also called rotating bezel, actually dates to the first diving watches of the 1950's. At the time, using a stopwatch was impossible, because every additional pusher could further compromise water-resistance, so instead they relied upon the bezel as a basic timing apparatus. Right before a dive, the wearer aligns the zero mark on the minutes hand. The bezel then indicates the minutes passed since entering water. To add security, the bezel can only be turned counter clockwise, meaning that if it were accidentally rotated, the immersion time would appear longer and the diver would be compelled to return to the surface earlier. During the 1960's and 1970's, the US and British Ministries of Defence also incorporated the bezel into military standard, either to display dive time or hours.",
"It can be used as a lapse timer or a reminder for a specific time. Turn the point on the rotating bezel to the current minute then at some future time you can see calculate how much time has passed without having to keep up with what time you started. Turn the point on the bezel to a specific time in the future as a reminder of some event at that time.",
"On pilot's chronograph watches, the bezel is used as part of a slide rule, used for calculations. Aviators used to rely on these to handle range and other navigational computations.",
"it's a timing feature. you turn the dial so the minute hand is currently on the number of minutes you want to count down, and you know it's been the correct amount of minutes when the minute hand reaches zero. it's originally for diving before digital watches. an alarm doesn't make sense under water and the old school watches didn't have stuff like flashing alarms or digital timers. it's mostly a traditional thing today, but i still use it from time to time, and sometimes when you're diving you may not want your watch to start blinking."
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5ptfy7 | How does Google Maps and other GPS calculate my estimated time of arrival? | I understand that Google has massive amounts of data available to them to calculate arrival time, but what do they use, exactly? For example, do they estimate as if you are going to drive the speed limit the entire drive or do they use the current data at hand and estimate that you will be driving the average speed of drivers currently on each road you will take? Further more, does it calculate for average slowdowns in certain areas on what time it is estimated that you will arrive in said area? For example, would it estimate for a rush hour scenario that you would hit 6 hours in the future if you were destined to drive through a populated city? If so, would it direct you around before you made it to that city? Sorry if I am not making sense. Edit: I'm on mobile and sorta high. Sorry for bad grammar and whatnot. | Technology | explainlikeimfive | {
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"It utilizes the phone signal from each device passing by the nearest towers and triangulates them to the closest ride. It it notices there are a lot of connected devices and none are connecting to the next tower then it will assume a traffic jam and average out the time it takes to move from one tower to the next. It does this for the most common and optimal routes to assume a time frame."
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5pti2o | Who/what is Anonymous? | Other | explainlikeimfive | {
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"Anonymous is/was a small group of highly skilled hackers, that were loosley organized together and somewhat activist or \"hacktivist\". They did some notorious hacks and denial of service attacks, and other cyber attacks. As well as being given hacked info that others did to help them and to distribute the hacked info. They were also known as LulzSec a group that existed before, though that name is less familiar than the iconic \"Anonymous\" and not all members of LulzSec moved over to the new group They also popularized the use of the Guy Fawkes mask, commonly known from the dystopian movie V for Vendetta. Most or all of the original members of the small group were eventually caught and charged with various crimes, with quite little fanfare, they were caught pretty solidly. After this, many other groups, related or not to the original group have also taken the \"anonymous\" title and headline as their names or who they represent, and often perform similar acts to the original group A good source for reading up more on the group, its origins, its people, and its begining, fall, and re-rise: [We Are Anonymous]( URL_0 ) by Parmy Olson"
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5ptiij | When you close your eyes and "look" at the sun, why is it that you see a reddish yellow color even through closed eyes? | Other | explainlikeimfive | {
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"Closing your eyes doesn't turn your vision off like switching off a television, it just blocks (almost all of) the light coming into them. The light passes through your eyelids which has blood vessels and layers of skin. Sort of like how putting a colored sheet of plastic over a stage light changes the color of the light (not exactly, but this is ELI5), the light passing through your eyelids is changed to the color of your eyelids.",
"I think that's the colour of your eyelids. It's the colour your fingers turn when you cover up a flashlight so it seems reasonable"
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5ptisc | Why do we laugh or smile when we are nervous | usually when we are unsure when something would work or something goes wrong that shouldn't. | Biology | explainlikeimfive | {
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"It is a psychological response to a threat. It is theorized we try to get others to like us by smiling at them, which is how anthropologists assume we became social animals. When we want others to like us, and not see us as threatening or give them a reason to harm us, we smile in attempts to get them to empathize with us. This response has been bastardized into other things that give us anxiety, like speeches or talking to girls, but it originally developed to protect us from getting our asses killed by other humans."
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5ptkaw | Why do all the planets appear on one horizontal plane in diagrams? | Physics | explainlikeimfive | {
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"Because they're mostly all on one horizontal plane in reality. [It's definitely not perfect]( URL_1 ), but it's pretty damn close. [Here's literally the first video I found explaining why planets form in one plane]( URL_0 ). I find a video helps because, at least for me, it's much easier to understand with a visualization (EDIT: And after watching it, it's not a bad video at all!). But basically, when you have a cloud of materials, as they clump together to begin forming the sun and protoplanets, they'll start to rotate, and as they collide and spin the dust and clumps will cancel the \"up and down\" movement relative to the plane [of the ecliptic] and leave a more or less pretty thin plane of planets and other junk.",
"They are for the most part. the largest deviation i believe is 15 degrees from the horizontal plane. this is caused by the solar system being formed by something called an accretion disk.",
"Because they pretty much *are* on the same orbital plane. URL_0 There a slight differences but there's no need for them to be reflected when your model isn't going to be to scale anyway.",
"Because they *are* all in one horizontal plane. I will quote from this site: [Why do all the planets orbit in the same plane? ]( URL_0 ) > The orbits of the planets are coplanar because during the Solar System's formation, the planets formed out of a disk of dust which surrounded the Sun. Because that disk of dust was a disk, all in a plane, all of the planets formed in a plane as well."
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5ptmgo | Why are some redirecting urls like URL_0 just as long as the origanal urls? | Technology | explainlikeimfive | {
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"A YouTube video ID is always 11 characters. Anything appended to the end is likely a marker pointing to a specific time (\"?t=75\" directs you to 75 second), an indication that the video is included in some playlist, or some other instructions like video size or window size, etc."
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5pto1o | Why did each (manned) Apollo Mission have a different crew? | I'm doing research for a paper on the Space Race during the Cold War, and part of that has been researching the Apollo Missions. I noticed that each of the manned Apollo Missions had a different crew on board. For instance Apollo 10 was basically a full test for the moon landing that would occur with Apollo 11, but without the actual landing part. Why did Apollo 10 and Apollo 11 have different crews? Why not have Neil Armstrong, Buzz Aldrin, and Michael Collins crew the test mission as well as the real mission? | Technology | explainlikeimfive | {
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"Good question... They had different goals/objectives on each mission. Everyone in that program got \"a piece of the pie\" and had to study the shit out of it/make it happen. Also, just sort of FYI, the crews did rotate (some people flew mutliple times). For example, Mike Collins could've walked on the moon but chose to end his NASA career after the first flight. Said it was so much stress and time away from his family, he decided if he made it through the first mission, that would be enough. And James Lovell was the Command Module Pilot (guy who orbited around the moon while the other two walked on the moon) on the Apollo 8 mission, and would have walked on the moon during Apollo 13 had things not gone wrong. Also, no one knew if \"moon germs\" were going to be an issue. So they had to be in quarantine for quite some time after each mission. Just a bit of an educated guess/jumping off point here - good luck with your assignment, sounds fascinating."
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5ptprj | Why do we grunt, yell, swear, ball our fists, grit our teeth, etc. when we're in pain? | Other | explainlikeimfive | {
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"Some think that doing all of the above activates the amygdala which is part of the fight-or-flight response. From what I understand it can also send endorphins to reduce pain. Its like the natural equivalent of smoking to reduce stress. URL_0"
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5ptpyf | how do computers tell time? | Technology | explainlikeimfive | {
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"There are three main engineering challenges to digital time-telling: - (A) Create a circuit that uses some sort of natural physical phenomenon to track the passage of time. - (B) Maintain accurate time when power is removed from the circuit. - (C) Keep the clock from drifting off the correct time. For part (A), we use a thing called *crystal oscillators*, usually using quartz for the crystal because it's cheap, has the right properties, and is common and well-understood in this application. Because of some complicated quantum physics stuff, you can take a quartz crystal of the right size and shape attached to the right supporting electronics, put a steady voltage in and get a steady stream of high speed pulses out. Millions or billions of pulses per second depending on how exactly you set it up. Add a digital circuit to count the pulses, roll over the \"seconds\" number once every however many million pulses it goes in an actual second, and check the system with a regular clock (or maybe a super duper stupidly high precision atomic clock) to be sure the number of pulses per second is right. Extra hardware and software can be added to the design for functions like displaying the time to the user, or any other time-based tasks like an alarm clock function. Almost any digital system these days contains one or more CPU's (that's the Central Processing Unit, the main part of a computer that does the actual computing) -- things like PC's, laptops, cell phones or game consoles have a pretty powerful CPU that's often \"front and center\" of marketing aimed at technically inclined audiences, to the extent that you even see commercials for Intel CPU's on TV. But even simple devices like microwaves or thermostats often have a *microcontroller* (a complete computer system including CPU, memory and other supporting circuitry on a single chip with very low performance, but correspondingly small size, cost and power usage). CPU's require a crystal oscillator to operate anyway, and many modern CPU's and microcontrollers have one built in, so it's usually just a matter of adding a fairly small amount of software code to harness the existing oscillator for a general-purpose clock, or any other timekeeping functions. For part (B), maintaining the clock without power, one answer is to add a battery to the design specifically for the purpose of keeping the clock running when the main power supply is cut. That's what's done in traditional desktop computers. Some other systems, like laptop computers, cell phones, and cars, already have a battery. The clock uses very low power so it's usually kept running even when the system's \"off\", except when the battery's completely disconnected. Of course, using a battery to keep time means you also have to have a fallback system to set the time whenever the system is restarted for the first time after a complete and full power cut including battery removal. For many devices, traditionally the answer has been that the user must enter the time in this case. However in the modern digital age, many devices connect to the Internet using NTP (Network Time Protocol). The current time is also available from the GPS (Global Positioning System) satellite signals. And the current time is also available over the cellphone network. And another possible answer to problem (B) is to deny that it is actually a problem that needs solving. That is, the designer simply accepts that the system will \"forget\" the time when the power's lost. Often you'll see a bunch of electronic devices around your place -- microwaves, ovens and alarm clocks -- all reset to midnight after a power outage (and sometimes blink or otherwise alter their display to indicate the outage occurred). For part (C), how to keep the clock drifting over time. It's impossible to make quartz crystals all 100% precisely identical. In other words, there is some error (deviation from the ideal tick speed), due to imperfections in the manufacturing process, and issues in the crystal's usage (basically temperature and the ability of the supporting electronics to supply a precise voltage). This error is usually small fractions of a second, but it can add up over many days, weeks, months or years of timekeeping. The traditional solution has been requiring the user to notice the clock is wrong and manually enter the correct time. But again, for modern systems, in many cases the system will be connected to an external machine readable clock source (Internet/NTP, GPS, cell network) which can be used to automatically correct the clock a couple times a day or so, before the drift has accumulated enough to make a noticeable difference.",
"They don't really \"tell\" it, they're just given it or get it from the internet and then keep track of it. Computers use a quartz crystal to keep time, as do almost all watches. The main element in quartz crystal, called silicon dioxide, has a piezoelectric potential which means when heat, pressure or any type of impact is applied, the electrons in the silicon dioxide begin to jump from their orbit and release a mild electrical charge that can be harnessed. The electrical charge is an oscillating vibration that is so constant and accurate it is harnessed for many things including keeping time."
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5ptpzl | How come people can taste substances that have been injected intravenously? | I've noticed I can taste whatever has been injected (Contrast Dyes, Vitamins, Morphine/Dilaudid etc.) and I've noticed other people have said they can too. What gives? | Biology | explainlikeimfive | {
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"There's very little between your mucus membranes and your blood. In fact, it's the second best of of administering certain drugs (by snorting them, or dissolving them under your tongue). It's just some of the chemical \"bleeding\" back through the mucus membranes that makes you taste it."
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5ptrdc | what's the difference between triple A games and other types of games? | Technology | explainlikeimfive | {
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"It's not a purely technical definition - the definition will vary from person to person and from context. Generally a triple A game is one that receives a large amount funding, normally from a major publisher, which is often visible in the number and quality of assets in the game. This doesn't necessarily mean the game is good (a major criticism of AAA games is that because they can't take risks with that much money on the line so they are cookie cutter games - identical sequel after sequel), just that the visual and audio components that is uses are pretty and plentiful. Think of AAA games like blockbuster movies. You can *see* the money spent on the screen in the form of big scenes, impressive CGI and lots of explosions."
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5ptryu | Why is it that some people can climb tall mountains like Mt. Everest without oxygen, but most people can't? | So the first man to climb Mt. Everest without supplemental oxygen was Peter Habeler, who is Italian. It astonishes me that some people can climb Mt. Everest without supplemental oxygen while most people will die if they do. What makes these human beings different than the rest of us from a physiological standpoint? I understand that Sherpas are really efficient at climbing tall mountains like Everest due to acclimatization and their ancestors living there for a while, which made them evolved to tolerate lower oxygen levels (correct me if I am wrong). But how do westerns, who do not live in places like Nepal, climb mountains like Everest without supplemental oxygen? Maybe Habeler was able to do it because he lived near the Alps? But the Alps are not as tall. Explain to me like I'm 5 please. I could not find a lot of information on this. | Biology | explainlikeimfive | {
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"Training. These people condition their bodies so they can last in high altitudes with little air",
"I just saw a tv show about this where they found a gene mutation in people native to Nepal that allow them to survive on less oxygen. They put an oximiter on a person from the USA and it was around 76% and heart rate was around 95 at rest. The Sherpa had oxygen of 95% and heart rate of 70. There was an extinct species of humans found buried in the caves that had genes found in the sherpas. I think the tv show was called the sky people or something like that."
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5ptsea | Why are the health benefits of sunlight not replicated by other light sources? | A doctor once told me I have low levels of Vitamin D, and so I should try to be outdoors for some amount of time each day. Why does sunlight help to increase Vitamin D levels, but other light (i.e., being indoors with lights on all day) does not? Is it just intensity? If that's the case, would blasting spotlights on my body do the trick? While we're at it, what is sunlight doing for plants that LEDs and incandescents are not? (Note: I rather love being outdoors. Not looking for a way to avoid it, just caught up on this thought.) | Biology | explainlikeimfive | {
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"Hey, this is fun - a chance to apply my real life job to an ELI5! I work for a narrow-band UVB device manufacturer, which uses UV-B bulbs to treat conditions like psoriasis and eczema. In short, there's nothing you get from the sun that we can't replicate with bulbs. But the sun puts out a HUGE range of the EM spectrum. Everything from UV-B, UV-A, the visible spectrum, and infrared. All of these wavelengths have different benefits. For example, recent studies have found visible blue light can kill certain bacteria on the skin that lead to acne, thereby giving you a clearer complexion. Red light can accelerate wound healing by increasing ATP production and collagen reshaping. With the sun, you're getting a dose of ALL of these various wavelengths that, for the most part, your body has evolved to receive. Companies like mine can replicate or, in the case of people like psoriasis, give extra-strong (but still safe!) doses of UV-B to treat conditions. SAD lights operate in the blue - UV range to stimulate vitamin D synthesis in the body, which can lead to increased happiness and mood during periods of low sun. TLDR: we can replicate everything about the sun using bulbs and LEDs, but what you get with the sun is a sort of evolutionarily-tuned dose of many, many wavelengths that have a huge variety of benefits, which is hard to replicate exactly in a clinical setting, even though each piece of said sunlight can be replicated.",
"Actually, there are lamps that stimulate vitamin D... They're marketed for treating Seasonal Affective Disorder (SAD) and they mimic the spectrum of light from the sun"
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5ptvgy | If fevers are part of our body's natural process to fighting off infection / viruses, why do we often take medication to take away the fever? | Biology | explainlikeimfive | {
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"The general consensus in the medical community is that fever may play a role in fighting infections. That being said, infections are not the only cause of fevers. When or if you should treat a fever depends largely on several factors such as the age of the person with the fever, underlying conditions, medical issues (for example, if they're immunocompromised, have cancer, are taking chemotherapy drugs, etc). Medications are generally taken to alleviate accompanying symptoms, not necessarily to get rid of the fever. Generally speaking, if someone under 3 months has a fever of 100.4 or higher, you should call the doctor. 3-6 months, if the fever is under 102, you should encourage rest and plenty of fluids. Call the doctor if they're irritable, lethargic, or obviously in pain. If it's above 102, you should call the doctor and likely be seen. Between 6 mo. and 2 years old, if the fever is below 102, medicine isn't warranted unless they're showing signs of pain (aching). If it's above 102, acetominophen or ibuprofen, in the proper dosage. Never aspirin. Call the doctor if the fever doesn't respond to ibuprofen or if it rises or if it lasts longer than a 24 hours. Older children, fevers under 102 don't need medication, just rest and fluids. The exception would be if they're showing/experiencing significant discomfort or they're lethargic, in which case, call the doctor. If they're aching, Ibuprofen can help. If the fever is above 102, as with younger children, use acetominophen or ibuprofen, never aspirin. Be aware that some other medications, like cold medicine, might have these in them so you don't over-dose them. Call the doctor if the fever doesn't respond or if it lasts longer than 3 days. Adults don't need to treat fevers under 102 either, unless the fever is accompanied by a stiff neck, severe headache, or extreme joint stiffness...in which case you should see your doctor. Above 102, again, ibuprofen/acetominophen. If you maintain a fever of 103 or higher for longer than 24 hours, if it doesn't respond to medication, if you have a fever (of any temp) for longer than 3 days, call your doctor. Elderly people generally have lower body temps, so a fever of 102 or higher is more significant than it would be in an average healthy adult. If you have a fever with no sweating, or accompanied by a stiff neck, seizures, severe headache, confusion, repeated vomiting or diarrhea, significant discomfort, rash, or above 104.5, seek medical care immediately.",
"The reason we have fevers is that most things that invade the body and make us sick can only survive in a narrow range of temperatures. When you have a fever, your body is cooking the invaders out. However, if the fever gets too high, you start to cook too, and that's not good for you. It's good to let a fever run its course as much as possible, but you can't let it get too high, which is why we sometimes take medication to suppress it. That might mean it takes longer to fight off the illness, but it mitigates the negative effects to you, and also makes you feel a bit better in the process.",
"We aren't supposed to unless it gets too high. If it gets so high that it's heating our internal organs, it can cause hearing loss, kidney problems, etc. That's why they say not to take medication for a fever unless it's over a certain degree. The medicine we take is usually meant more for the discomfort/pain. Medicine to control a fever is only in extreme cases or when it involves a child.",
"Can I ask something relating towards this as well, we feel physically cold and I remember needing like 2 blankets to warm myself, even though my temperature is actually already high. Is this instinct or is my body trying to kill me faster?"
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5ptxqz | Why are aquariums lit by blue lights? | Other | explainlikeimfive | {
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"Fish store manager and avid aquarist here! There are several reasons! Side note, that blue color is called \"actinic\". First of all, it's more \"natural\" [for saltwater tanks]. Lower frequency light, the red side of the visible spectrum, is absorbed pretty quickly in water. That leaves more high frequency bluish light, which is why [underwater pictures have a lot of blue]( URL_6 ). A fish tank isn't as deep as the ocean (duh), though, so when you shine a white light into your tank, the reds don't have time to be absorbed before they're reflected out of the tank and into your eyes. Tanks lit with bright white lights often look \"unnatural\" because of that - the colors aren't what you would expect to see if you were deep underwater. Many aquarists are also divers, and they want to bring a part of that experience home with them with a tank. Even those that aren't divers still often want to create that underwater blue mystique. That's what actinic lights are for. They overwhelm the other colors coming from the white to give you that deep, piercing blue that you find underwater. Too much actinic also looks just as weird, though, which is why an ideal [saltwater] tank blends actinic light with whites to create the right balance to look natural, especially a reef tank with live corals. Exactly what blend of white and blue you want for your tank is mostly a matter of taste. That brings us to reason number two: corals fluoresce under the right light. Fluorescence is the absorption of one frequency (or several) of light, and re-emitting that energy as lower frequency light. This is how black lights work: they put out very high-frequency violet and ultraviolet (not very visible and invisible, respectively, to our eyes) and your [psychedelic paint]( URL_8 ) absorbs it and emits light you can see better, which makes them look super bright and colorful. Corals do the same thing. Corals can be [ridiculously colorful]( URL_3 ) and [amazing]( URL_1 ), and actinic light helps bring out a lot of those colors by making them shine, just like stuff under a black light. [Here's a picture comparing an acropora coral under typical white light and under actinic blue light]( URL_7 ). You can clearly see that incredible green color fluorescing under the actinic! Corals *do* also fluoresce under UV light, but not as well as actinic. This makes sense, since 1) UV light doesn't penetrate very well into seawater, so corals wouldn't evolve to interact with it much, and 2) actinic *does* penetrate *very* well into the water. Not all of a coral's color is seen best under actinic, though - some corals look great under white light, too, so again a mix of white and actinic is preferable. *However*, corals do *not* grow primarily from the actinic light, as someone else suggested. They do receive some usable energy from the actinic, but they need a range of frequencies, including a tiny bit of red! [This article goes into some detail]( URL_0 ) but if I had to boil it down I would point to [this graph]( URL_0 _album/image007.jpg) (actinic is generally considered around the 450-440nm range) which is the spectra of light absorbed by zooxanthellae - which are the \"algae\" that corals host in their tissues to photosynthesize food for them. (If you'd like a little more information about the relationship between zooxanthellae and coral, I'll toot my own horn a bit and point you [here]( URL_5 )). Basically, that graph shows which parts of the light spectrum the corals are \"using\". *Except* that the graph just shows what's being not being reflected, not necessarily which parts of the spectrum are specifically being used for photosynthesis. The topic of what spectrum is the most important for coral growth is a topic of much debate, particularly in the aquarium hobby, which is made difficult by the fact that there are thousands of different species of corals, *and* the same species of coral might have different species of zooxanthellae algae living inside of them... It's complicated, is the point. Also the point: most of your growth comes from the white lights over your tank. Remember that \"white\" means \"a combination of all of the visible spectrum\", so exactly what parts of the white are being used for growth is not fully known (at least to me, maybe there's a marine biologist around that knows?). All of this has been talking about *saltwater* tanks. Freshwater tanks usually do *not* have actinic lights over them, although some people do still use them to create that same \"I'm totally in the ocean\" mystique even with freshwater species. Actinic lights are particularly good over [Glofish^^TM]( URL_4 ), which are genetically modified freshwater species that fluoresce just like corals (more accurately, like jellyfish, since the modified DNA came from jellyfish). **PRO TIP**: Use actinics over your Glofish, not black lights - they'll glow brighter and your tank will look better that way! But most freshwater tanks look better with a slightly *redder* spectrum. First, because bodies of fresh water tend to be much shallower than the ocean (duh) so there's more red light to go around, but also because a lot of freshwater fish have a little bit of red in them. It makes great camouflage, since red light doesn't last underwater (so there's no red light to reflect off of their red pigment, making it dark and hard to see) and freshwater systems tend to be much murkier and muddier. Wood can also affect water, releasing tannins, which are the chemicals that make tea and whiskey the color that they are (a slightly reddish brown). By putting a slightly reddish light over your freshwater tank, you reflect off of that red and get a little more color out of your fish. Red is also a more important part of plant photosynthesis, so lights designed for plant growth will have more red light than a light designed for coral growth. TL;DR: it looks more natural because water is \"blue\" (it's not but it looks that way) so a blue tank makes it seem like you're underwater, and corals look waaaaaay cooler under the blue lights, although they probably don't use much of it for growth...probably...maybe. EDITS: clarifying some minor things here and there."
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5pu1a2 | What is Altitude Sickness and why do people get it? | Biology | explainlikeimfive | {
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"Oxygen pressure lowers the higher up you go, the lower the pressure, the less oxygen available so less gets to your brain and other vital organs. This leads to bad effects over a short time from not being able to think straight to physical weakness. Edit: for more in depth than ELI5 this would be a useful link: URL_0"
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5pu36m | How were the values of constants such as e and pi historically determined, and why do these constants find themselves in so many formulae? | Mathematics | explainlikeimfive | {
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"As you probably know, pi is intimately connected with circles. Whether you regard pi as the ratio of a circle's circumference to its diameter or the ratio of its area to the square of its radius, etc., pi can be seen to be connected with circles. It should come as no surprise that you can find pi whenever you're working with circles. Circles come up all the time in math even if you have to squint pretty hard to find the circle. For example, many of the occurrences of pi have to do with trigonometric functions like sine, cosine, and tangent. These functions can be thought of as relating an angle (which is really part of a circle under a loose definition of \"part\" and \"circle\") to the ratio of sides of a right triangle having that angle. These functions come up in geometry and trigonometry, of course, but they also come up in waves. (For some motivation here, look at the graph of the sine function). Waves are very important in physics for a number of reasons, notably electromagnetic radiation. (Whether this is really a wave or a particle or both or neither is the topic of a whole other eli5, but suffice it to say that even in answering this question properly you come to things called wave functions.) f(x) = e^x is a unique function because the \"slope\" of the function (technically the derivative if you know a little calculus, if not imagine drawing a straight line that just touches the curve at one point, almost bouncing off, and taking the slope of that with rise over run) at a point is equal to the value of the function at that point. This is one of the reasons e crops up everywhere because it represents exponential growth. When the rate at which something is changing is related to the amount of something there is at a given time, look for an exponent. Of course lots of numbers could be used for an exponent, but because e^x's slope equals its value (rather than being proportional to the value like 2\\^x, for example) e is often how mathematicians will write the equation. Since a^x == e^(ln[a] x), for any positive a, any time you see an exponent you could rewrite it in terms of e. (For an explanation of this fact consider the rules of exponents and that ln(x) is the inverse function of e^x, so e^(ln x) == x and ln(e^x)== x). Another reason the two numbers come up so often is actually a deep connection between trigonometric functions and e^x. In order to understand this relationship properly you need to understand Taylor series. A Taylor series is an infinite sum. By that I mean the sum has an infinite number of terms, not that the value of it is infinite. It turns out that if the things you're adding shrink fast enough you can add an infinite number of things and still get a finite number. Anyway, what a Taylor series does is approximate a function by an infinite sum of polynomial terms. Intuitively, you can approximate a function around some value, a, by looking at the value of the function at a, f(a). This works for that point, but probably not for points near a like a+0.000001. To get a little better, you can approximate a function by a straight line passing through f(a) but having the same \"slope\" at that point. To get a little bit better still you could approximate the function by a parabola, g, which has the same value at a, the same slope at a, and the same slope of the slope at a. That is g(a) = f(a), g'(a) = f'(a), and g''(a) = f''(a). You can keep this process going forever and you do a better and better job of approximating the function. Ok, where does e come into this? Well, back before we mentioned that the slope of e^x at x is simply e^x. That means when we were taking the slope and the slope of the slope, etc., we kept getting things that look like e^x. I didn't mention it above but in order to use all of those slopes you have to scale by some constants that don't really matter for our purposes at the moment. In any case, e^x 's self similarity means that the Taylor series for it at x= 0 looks like this: x^0/0! + x^1/1! + x^2/2! + x^3/3!... which is one of the prettiest Taylor series you can have. All right, that's e, but what does that have to do with sine and cosine? Well, sine and cosine have similar properties to e^x. The slope function of sin(x) isn't sin(x), but it's cos(x). And the slope function of cos(x)? Well, that's just -sin(x). This means that the slope function of the slope function of sin(x) is -sin(x). It's not quite self-similarity, but it's pretty close to it. Because sin(0) = 0, the value at zero of the slope of the slope of sin(x) is also 0, and this holds true for any even number of \"slope function of\"s. You can make a similar argument for cos(x) but with odd numbers. Well, this means that the Taylor series for sin(x) around x=0 ends up being x/1! -x^3/3! + x^5/5! -x^7/7! + x^9/9!... and cos(x)'s ends up as 1/0! - x^2/2! +x^4/4!... Well, if you squint you might already be able to see a connection between sin(x), cos(x) and e^x, but we'll drive forwards a bit more. I'll assume you're familiar with i, the imaginary unit, the square root of -1. Some people struggle with imaginary numbers because they don't show up too obviously in ordinary life, but, believe it or not, they're there. You just have to look for them. If you don't like imaginary numbers you probably won't like what happens next, but it's pretty cool. It turns out we can make sense of something like e^(ix) even though that seems a little strange. How can we make sense of it? Taylor series! e^(ix) == (ix)^0/0! + (ix)^1/1! + (ix)^2/2! + (ix)^3/3!... A little bit of algebra will let us factor that series into something like (1/0! - x^2/2! +x^4/4!...) + (ix/1! -ix^3/3! + ix^5/5! -ix^7/7! + ix^9/9!... ) == cos(x) + i sin(x). Whoa, that was crazy! It is from this fact that we have e^(i pi) = -1 since e^(i pi) == cos(pi) + i sin(pi) = -1 + 0 = -1. One of my favourite surprising occurences of pi is in the probability distribution for the standard normal, or Gaussian, distribution. This distribution is the famous bell curve you may have heard about. The Central Limit Theorems in statistics tell us that the sum of lots of little distributions approximate a normal distribution if you sum enough things. It's this theorem that helps explain why things like height of males or height of females within a population tends to follow something that looks like a bell curve. When you try to get a formula for this magical distributions others converge to you end up working with infinite series again and for detailed reasons that probably can't be eli5'd e pops up again. Through this e, pi pops up too! Now we have the circle constant showing up for population structure statistics. That's pretty weird at first glance. Now for how they could be calculated. One way to calculate pi is to draw a circle, measure its diameter, measure is circumference, and divide the circumference by the diameter. This works well enough for getting an approximation like 3.14 but it's tough to get an approximation too much closer than that because you're relying on how well you can draw a perfect circle and how well you can measure. Another way pi was calculated, historically, is a method famously associated with Archimedes. Imagine drawing a triangle with all sides and angles equal. A polygon with all sides and angles equal is called a regular polygon. Now imagine that the triangle has its points lying on a circle. We'll call this a circle circumscribing the triangle. It may not be obvious that you can draw a circle like that, but you can. Now imagine the same circle, but we'll draw a triangle around the circle with the edges of the triangle just touching the circle. Now we'll say the circle is inscribing the triangle. If you think a little bit, it should be clear that the perimeter of the inner triangle is less than the perimeter (or circumference) of a circle. Similarly, the perimeter of the outer triangle is greater than the circumference. It turns out you can do the same thing for regular polygons with any number of sides. The more sides you have, the closer the shapes will look to a circle, and the closer their perimeters will be, but the circle that's inscribing one and circumscribing the other will always have a circumference in between their perimeters. There's a fairly nice way to calculate the perimeter of a regular polygon and the diameter of its inscribing/circumscribing circle without doing any measuring. That means we can pick some really big number of sides and get two perimeters that are very close together. Once we've done that, we know that the circumference is somewhere in between. Now we just divide the estimated circumference by the calculated diameter and we have an estimate for pi. This method was popular for over 1000 years, but it was eventually beat out by methods involving infinite series (which probably have something to do with circles if you squint hard enough and look for trigonometric functions). Human knowledge of e is a lot younger than human knowledge of pi. We've only known about e since somewhere around the 1600s. Because of this, there's less history about how it was calculated. There are lots of ways to calculate it just like there are lots of ways to calculate pi. Almost all of them look at infinite series in some way. If you've been paying attention you might see that you could use a Taylor series for e^x (around 0) evaluated at x =1 to calculate e. This method works reasonably well and it's relatively simple so it's a good way to think about it. There are lots of other ways to calculate it, though, and I'm guessing this wasn't the first way it was done, but maybe.",
"Imagine if you took a circle (area = pi* radius squared) and measured it's area and radius physically without doing any calculations, then for fun you randomly divided area by radius squared. You do this several times before realizing you always get the same number: 3.14159....... so it's easy to just define that number as pi and remember the value of it for future use.",
"Pi is the ratio of a circle's circumference to its diameter. This ratio crops up basically anywhere you have circles or spheres. It's determined by simple measurement. The derivative of e^x is e^x, which is unique. This means that the slope at any point on the curve is equal to the y-value. This is supremely important for any quantity that changes based on the current quantity, for example radioactivity. Each atom has an x% chance of decaying over a given time period, so the amount left is (1-x) times the total amount. The resulting graph is e^-x . Other numbers can be used, like 2^x or 10^x, but again, e's derivative is better. You can switch between them easily, thankfully. This constant can easily be determined with a series of x^n /x!. And you might have seen e^pi*i =-1. This is because e raised to any imaginary value e^ix can be expressed as i sin x + cos x. The sine of pi is zero and the cosine of pi is -1, so that's how that formula works."
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5pu6mg | Why do some foods taste better cold and some hot? Is it strictly cultural, or are certain tastes more apt to be pleasurable at a certain temperature biologically? | Biology | explainlikeimfive | {
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"It's more physics, actually. Flavor is as much scent as it is taste. Certain foods taste better because heat allows scent molecules to move faster which mean they move into your nose quickly and you can taste them. Try this experiment: Eat something sweet, chew it up, and focus on how the taste hits your mouth. after you swallow it, eat a piece of the same food again, but hold your nose closed as you chew. You'll notice that it doesn't taste the same way. Cold foods taste the way they do because there's a taste change between when you first put it in your mouth, and when the heat of your mouth heats up the scent molecules to go up inside your nose via the back of your throat. As to which foods are better cold vs hot, that tends to be cultural. You'll see certain cold foods popular in hot climates to help cool the body down. you'll see certain hot foods popular in cold climates because it makes you warm. There are millions of opinions on the whys and the wherefores of the matter and one single theory explaining everything does not exist yet."
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5pubqu | How does working out in the morning give us *more* energy through out the day when our body is using energy to work out? | Titles says it all. I looked through ELI5 to see if someone else had asked this question, I could not find anything. Thanks! | Biology | explainlikeimfive | {
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"Well this is a leading question, because you're assuming, by fact, that working out in the morning *definitely does* make you more energetic throughout the day, which is not a guaranteed fact. But I am being nit-picky. Regular exercise *does* indeed make you feel more energetic, and it isn't necessarily time-dependent. Regular exercise, whether AM or PM, most often makes you feel more energetic throughout the whole day. To answer this question though, its very important you understand a key difference: your *actual bodily energy stores* and your *feeling of bodily energy* are two very, very different things. A great deal of the time, especially in our modern, more lethargic society, we may *feel* tired, but we have in reality an abundance of energy; most of us are walking around with plentiful fat stores that could easily carry us through a week of no food. Your body is a thing of routine. It always acclimates to satisfy its expectation. If your body things its going to do nothing but sit around, you will *feel* tired, because your body is accustomed to *not* spending energy. Exercising regularly increases the demand for muscles, and for ambulation (movement) in general. Excercise increases certain bodily hormones, including ephinephrine, norepinephrine, and dopamine. These have the effect of dulling the pain from exercise, but they also dull pain globally, which makes you feel happier, more alert, and more energetic. Our bodies were made to move, and moving is closely tied to our pleasure center. Your body associates movement with getting food, because in the prehistoric age, we moved to get food, that was the excercise. So your body rewards you generously in the form of hormones. There are a lot of very complex interactions in addition to this, some of which are short term, and some of which are long term after long periods of daily exercise."
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5pudl2 | How does 20th Century Fox, Universal, Sony Pictures and Lionsgate own rights to some of Marvel's characters in film even though Marvel made those characters originally? | Other | explainlikeimfive | {
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"Marvel sold movie and TV rights and such to a lot of their characters (such as Spider-man, X-Men, and the Fantastic Four) many years ago when they were going through some troubles in their business. It helped keep them afloat, and increased their popularity, and frankly, Marvel wasn't doing much with regards to producing film/tv anyways, they sold them to people who could actually do something with their characters. Not a bad call at all. They still retained rights to many other characters, such as Iron Man and Captain America. What happens in the future, if Fox and such keep those or if Marvel tries to buy them back, or they make some other type of agreement is unknown.",
"As mentioned already, Marvel sold the rights to various studios to get them out of financial trouble before they were making movies and television. However, a lot of characters remained with Marvel because at the time they weren't classed as \"big hitters\", heck Iron Man was classed as a \"b-list character\" when Marvel Studios first ventured into filmmaking and it all rested on that; had fans not loved Iron Man, Marvel Studios may have gone away because they just didn't have the big characters due to selling them off to other studios. Many characters and properties however naturally reverted back to their originator, Marvel, after their contracts expired with various studios (Daredevil, Blade, etc) because nothing was happening with them. But just to delve a little deeper about retaining the characters, it's difficult for Marvel to get certain properties back whilst films are still being made. There's a lot of talk about this supposed bad blood between Marvel and FOX, hence why there hasn't been a deal between Marvel and FOX to share their respective universes like Sony and Marvel have done for Spider-Man. However, I'm not actually sure if there is any bad blood at all - it boils down to a simple fact; the X-Universe may not crush it critically but they never fail to make profit from their films, so they have no reason to share their characters and stories with Marvel. Whereas Spider-Man, despite still making a profit, saw their profits starting to dwindle and critically since Spider-Man 2 haven't really wowed anybody. I mean, nobody really hated TASM but it wasn't universally loved either, and again with TASM2 - many people viewed it as a bit of a mess and repeated the same issues as the critically panned Spider-Man 3 (particularly with being over-stuffed with villains), and it grossed less than any Spidey film to-date. Sony had good links with Marvel anyway, so they made a business decision to get ahead of the dwindling enthusiasm by scrapping their universe and put Spidey in the Marvel Cinematic Universe, which most will agree has consistently made big profits and pleased fans and critics alike. Let's also not forget the creative head of Marvel Studios, Kevin Feige, used to work for Sony as an executive producer on Spider-Man 2 and Spider-Man 3. There was already an existing relationship there, despite being considered \"rivals\". It was always a fairly friendly rivalry there, to the point where Andrew Garfield (Peter Parker in the last The Amazing Spider-Man films) actually encouraged Sony to team up with Marvel before. Sony, like FOX, at the time felt they didn't need to and could form their own Spidey-centric universe. Only when profits dwindled and critics/fans started to lose enthusiasm, they got ahead of the curve. In this case, Sony still own the rights entirely to Spidey and his characters, but Marvel (and Sony) now produce those films in an attempt to get Spidey back on track as a character with fans so Sony can reap the rewards, especially financially, but in turn, allowed Marvel to put Spidey in any film they wish within their own current roster. It's working out wonderfully for both studios involved. It's made a lot of people say \"why on earth wouldn't FOX want to do this as well if it's working so well with Sony/Marvel?\" - simple answer is that FOX don't think they need to share, financially at the very least it's ticking the boxes just fine without the behemoth that Marvel Studios/Disney has become. It's become a LITTLE murkier with Scarlett Witch and Quicksilver being both owned by Marvel/FOX and that's why we've seen different iterations of Quicksilver, but that's a whole other thing. Personal opinion; I'll be interested to see what happens with Fantastic Four; on both sets of films FOX have put out have been rushed out with the aim to retain the rights and stop them reverting back to Marvel. However, now Fantastic Four utterly bombed and it's not looking likely FOX will bother overly with it in the future, a deal maybe made with Marvel to revert the rights back to Marvel at some point in the future. FOX, if at all, won't let it go back to free - but who knows, a rights deal may be worked out. I know Marvel Studios own the TV rights to the X-Men on the small screen, so maybe a deal can be worked out where FOX swap the Fantastic Four rights for the X-Men TV show rights, which would benefit everyone as Marvel aren't going to do an X-Men show given they don't own the movie rights. It would just confuse the general audiences, so it'd make sense for both FOX and Marvel to do that deal - whether it'll happen though, I couldn't say with confidence that it'd ever happen."
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5pufu6 | Sharia Law | For the past 8 years, I have heard about Obama's "plans" to enforce it, and with the new controversy regarding one of the coordinators of the Women's March, it's come up in conversation again. I've never understood what it is or how it works. Could someone please explain? Much appreciated! | Other | explainlikeimfive | {
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"Well first of all, what you heard about Obama or anyone in the WM is completely bunk and total and utter nonsense. The word *Sharia* IS law in Islam, so saying \"Sharia Law\" is a bit of Fox News manufactured redundancy for people who don't understand it. Sharia is Islamic Law based on the Koran. In states like Saudi Arabia, the government is a religious government. Thus, their laws are based in the Koran (even though their interpretation is questionable). The state makes and enforces laws directly from the Koran. People (idiots) who claim Obama is going to bring about Sharia are conspiracy theorists who are convinced he is a muslim, and therefore would inject Sharia into American law. Again, this should be obviously, blatantly ridiculous to any thinking, breathing human being, but as there were major news networks continually reinforcing this absurdity, I suppose it stands repeating.",
"• Theft is punishable by amputation of the right hand. • Criticizing or denying any part of the Quran is punishable by death. • Criticizing Muhammad or denying that he is a prophet is punishable by death. • Criticizing or denying Allah, the god of Islam is punishable by death. • A Muslim who becomes a non-Muslim is punishable by death. • A non-Muslim who leads a Muslim away from Islam is punishable by death. • A non-Muslim man who marries a Muslim woman is punishable by death. • A man can marry an infant girl and consummate the marriage when she is 9 years old. • Girls' clitoris should be cut (Muhammad's words, Book 41, Kitab Al-Adab, Hadith 5251). • A woman can have 1 husband, who can have up to 4 wives; Muhammad can have more. • A man can beat his wife for insubordination. • A man can unilaterally divorce his wife; a woman needs her husband's consent to divorce. • A divorced wife loses custody of all children over 6 years of age or when they exceed it. • Testimonies of four male witnesses are required to prove rape against a woman. • A woman who has been raped cannot testify in court against her rapist(s). • A woman's testimony in court, allowed in property cases, carries ½ the weight of a man's. • A female heir inherits half of what a male heir inherits. • A woman cannot drive a car, as it leads to fitnah (upheaval). • A woman cannot speak alone to a man who is not her husband or relative. • Meat to eat must come from animals that have been sacrificed to Allah - i.e., be \"Halal\". • Muslims should engage in Taqiyya and lie to non-Muslims to advance Islam. My proof: Been a Muslim for 15 years {Mods this is the truth don't remove this because it might offend others.}",
"I'm not a fan of Obama but the idea that he was going to enforce Sharia Law is absurd. Sharia Law is just 'Law' in the Islamic sense, and details punishments to crimes as written in the Quran. However, whilst other religions have moved past some of their equally harsh practices described in their Holy Literature (Christianity discussing stoning gays for example) the influence of Wahhabism and Conservative Islam in the middle east has meant that many Muslims and Islamic nation have still clung to these rather outdated or extreme punishments"
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5pughp | Why are birds (i.e. Parrots, Crows, Hawks, etc) so intelligent if they have such small brains? | Biology | explainlikeimfive | {
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"First off, gross brain mass is irrelevant. Among mammals, brain to body mass ratio appears to be a good indicator of relative intelligence. Not perfect, unless you want to admit that dolphins are smarter than humans. Among other species, avian say, the same URL_2 hold true: with corvids (crows and ravens and such) and parrots having higher brain to body mass ratio than those stupid Robins. However, they still have a lower brain to body mass ratio than comparably intelligent (and that's a tricky distinction in itself) mammals. That said, bird brain cells tend to be a bit smaller, so possibly more neurons per pound of grey matter. References: all wikipedia : URL_0 URL_1"
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5puhx2 | Joyful people are said to have a twinkle in their eyes, what physically changes in a depressed or sad person's eyes to create the "dead eye" effect? | Biology | explainlikeimfive | {
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"Emotionally healthy people emote with their eyes. When they smile, the outer corners of their eyes tend to wrinkle. They raise their eyebrows when they're happy to see you. They look around to see the world and to observe others. Their eyes, in other words, are \"alive.\" Depressed people either don't feel these things, or spend so much time not feeling them that they lose touch with how they'd usually express them. A depressed person will smile with their mouth, but not their eyes. They won't move their gaze around to see the whole picture - they don't care. They basically use their eyes strictly as a tool to grab certain information and not trip over things. They might not even be paying attention with their eyes, or with any of their senses. They might point their eyes at you just so you'll think they're fine. In other words, their eyes are \"dead.\"",
"My eyes used to sparkle. I can't remember how I made them do that but I have been depressed for twenty years. It's easy to forget.",
"That twinkle comes from natural lubricant on the eye's surface. When eyes connect exactly with someone else's, they reflect light back and forth creating a sparkle/reflective effect. When people are happy they have a greater likelihood of making more eye contact, depressed people tend to avoid it and thus no sparkle while tired and worn out eyes will be less lubricated and other signs of fatigue such as redness or dark circles will offset the twinkle too. Additionally, when you smile, you squint, increasing the depth of the lubricant, by reducing the surface area of the eyeball with your eyelids increasing the amount of sparkle on the eye.",
"I'm surprised no one's mentioned pupil dilation. The \"thousand mile stare\" is mostly unfocused eyes with the pupils dilated. The lids also stay in a neutral position. It looks like \"giving up\" because our brains can recognize there's no effort being expended by the eyes. A normal \"happy\" expression involves a very slight narrowing of the eyelids and the pupils narrowed to a near focus. \"Dead eyes\" and \"twinkling eyes\" aren't so much expressions as micro expressions- the language is just our way to articulate recognition of changes that are so subtle that they've been borderline subconscious until very recently.",
"Just look at an air hostess on a commuter flight. You will see dead eyes on a face forced to smile.",
"Any literal twinkle/sparkle must come from reflected light. In most situations, lighting cones from above. In order for you to see a reflection of that light on someone's eyes, you have to see a portion of their eye that is on an angle somewhere between the angle facing the light and the angle facing your eyes. Depressed people tend to look downwards more than up, and tend to have their eyes less than fully open/half lidded. On average, the angles that would show a reflected light are covered by their eyelids or shadowed due to their downcast gaze. Add this to the general lack of energy and emotion in their eyes and you get the dead eyed effect.",
"I feel like unless you've been blindsided by having your heart ripped out by someone you were in real love with that you will see that same look in people or through peoples facades of being okay."
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5pusrw | Counting Cards in blackjack | Mathematics | explainlikeimfive | {
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"A standard deck of cards has four of each value: four Aces, four Kings, four Queens, four Jacks, etc. These cards are shuffled up so that they're in a random order. In most blackjack games, the deck is not re-shuffled after every hand. Rather, the used cards go into a discard pile and the **next hand continues with only the unused cards**. Therefore if you keep track of the cards that were already used, you have a general understanding of what cards aren't used yet (and might be coming up). For example, if you know that all Kings have already been used up, then you know for certain that the next card can not possibly be a King. When laymen are talking about card counting, they are usually referring to the hi/lo system. The hi/lo system doesn't keep track of *exactly* which cards were used (because that would be too hard), but rather just counts if high cards or low cards have been used up. If there are a lot of Tens (face cards count as Ten) and Aces remaining unused in the deck, then the player is at an advantage. This is because the dealer is more likely to bust, and also because the player is more likely to get a blackjack dealt. The way counting cards works is that you sit at the table and bet small amounts in the beginning. At the beginning, you don't know if you will see high cards or low cards. Sometimes, the high cards come out in the beginning. This means that the rest of the deck has a bunch of low cards and you won't get an advantage. You continue to bet small amounts. Sometimes, the low cards come out in the beginning. This means that the rest of the deck has a bunch of high cards. This is when you have the advantage so you bet big amounts. If you're betting $5 per hand when you're expecting to lose, and betting $500 per hand when you're expecting to win, you can see how this is a possible way to make money. (Edit: added bold for emphasis)"
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5put8i | Why do tennis players use stationary cycle right after a match? | I have recently seen Rafa and Wawrinka do this. What is the reason/logic behind this? | Other | explainlikeimfive | {
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"It's to help them warm down from a match so they can recover faster and all their muscles don't cramp up. It helps remove lactic acid that's built up. They have about 10 minutes on a bike then eat a lot of carbohydrates and protein based food. Iirc Andy Murray normally eats loads of sushi after a match."
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5puuuz | How is the ink permanantly sticking onto the paper but can be erased from the hand? | Other | explainlikeimfive | {
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"You mean erased or washed off? Pen doesnt wash off easily. The difference is your skin isnt a solid piece like paper. It has different layers of living and out on the outside dead cells. By washing your hands or rubbing hard, you remove all the layers that can in contact with the ink",
"Paper is very porous, it has wood fibers in it, trees needs to be able to suck up water to it's leaves. So the ink gets into the whole 3D structure of the paper, not just on the surface. So you need to do a lot more than washing off the surface to get rid of the color, probably you'd need to do something rough enough that it destroys the paper in the process. Your skin on the other hand is pretty waterproof (at least that's what the captain told us in the military when we complained we'd get wet if we crossed the river), so you just wash off the surface. Furthermore, it's a lot tougher than paper so you can be rougher when cleaning it off. **If you get a tattoo on the hand, that's also ink, but it goes in depth, just like when writing on paper, and it cant get washed off!**"
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5puxud | Why does a real person who is speaking right next to me sound so different from a person on TV, apparently speaking right in front of me? | Physics | explainlikeimfive | {
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"1. As mentioned above, the quality of television speakers. 2. In a real conversation there is some other sound going on. The wind is blowing outside, your house is creaking you are tapping your foot, you are moving in certain ways. There are a thousand factors in the real world that alters the sound. Essentially no film or television show (including \"reality\" television) uses the sound recorded on set. Instead, they will film the actors, take a basic recording, and on a later date [put the actors in a sound proof box with a mic in it]( URL_0 ) and have the actors say their lines *again*, probably while listening to their original recording lines to match the speed/tone of it. This perfect audio, where there is nothing that is distorting the sound and the only other noises you hear are the sounds the director/editor adds to the scene. [Here is a demonstration of the difference]( URL_1 )."
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5pv0ti | Why exercise is more beneficial than resting when it comes to organs, specifically the heart. | I'm just curious as to why stressing out the heart during exercise makes it stronger and last longer versus a heart that got to rest more. i.e A person that works out versus a person that lays on the couch any chance they get. In my mind, it seems like someone who is able rest all the time would have a better heart because it didn't have to deal with the strenuous activity of exercise. I know it doesn't work that way thought. | Biology | explainlikeimfive | {
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"The heart is a muscle. Use it or lose it. Like, if you use your heart often you are training it like any other muscle, so when you have to do some heavy work when you are a couch potatoe you are more prone to heartattacks and what not, because your heart isn't really used to do all that work."
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5pv8j8 | How do fishermen on those large trawlers with nets catch the exact fish they are looking for? | Technology | explainlikeimfive | {
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"text": [
"The fishing spots are not randomly chosen. They are chosen because there is a lot of the desired fish there. Different fish will have specialized themselves to feed on different food, swim at different depths and handle different ocean conditions. So if you go to the place that best fits the fish you are after and throw your net you have a good chance of getting the right catch. The nets is also a complex piece of equipment designed to only catch fish of the right size and shape. Too big and the fish will not be able to enter the net, too small and it can flee through the net. Finally a lot of fish travel together in steams. These steams are visible on sonar and you can even see the size and shape of the fish to find out what kind of fish is in the steam. A trawler can then throw its nets and catch the entire steam at once."
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5pvef0 | Why Do We Tend To Notice Things in Pairs? Or, why does there seem to be a general consensus that even numbers are more, "attractive"? | Biology | explainlikeimfive | {
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"I've always looked at it as it has to do with being symmetrical. You can divide even numbers into two equal halves. When you look at someone and find them attractive their face is normally symmetrical. People without birth defects have symmetrical sides of the body, two arms, two legs, ten fingers and so on. This might not be as scientific as you were wanting, just my two cents."
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5pvh97 | Why is it recommended to not sleep for a while when diagnosed with a concussion. | Was diagnosed with concussion yesterday, have been several times before (sport-related). When I tell people, they often tell me to make sure I don't go to sleep for a while. Where does this come from? Is it based on any actual medical advice? | Biology | explainlikeimfive | {
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"A concussion is a functional injury, which means you'll have difficulty operating at 100% for varying amounts of time. Sleep is the best way to heal said concussion. Staying awake right after a concussion is helpful in assessing if there is also physical damage, such as swelling or bleeding in the brain. But if you have no issues walking, or holding a conversation, and neither of your pupils is dilated, rest is your best option for healing the concussion.",
"For a long time people attributed death to people's going to sleep, due to diminished consciousness that happened after severe brain injuries. This isn't a relevant factor, because passing out (and wanting to) is a symptom and not a contributing factor; but in current medicine it's a pretty good idea to stay awake and seek medical attention after any serious injury. EDITED: Made the wording less stupider.",
"With a patient suffering a concussion, first responders are meant to keep patient awake, as without specialist equipment and staff it is very difficult to tell the difference between someone sleeping and someone unconscious.",
"It was believed for some time that if one went to sleep after a head injury, they'd be more likely to slip into a coma. Doctors now believe that rest is actually good for someone with a concussion, as it promotes healing. They recommend staying awake for 4 hours, which is a window of time to allow any other potential symptoms to show up (dilated pupils, incoherent or slurred speech, etc) that could indicate the injury is physical as well as functional. If the person with a concussion is able to speak and understand normally, they should definitely get some rest."
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5pvnxq | what is a superfluid? | Chemistry | explainlikeimfive | {
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"\"Superfluidity is the characteristic property of a fluid with zero viscosity which therefore flows without loss of kinetic energy.\" An example is: Helium!",
"A superfluid is a fluid with no inner friction. This is usually only achievable by cooling down some gases like Helium to ~2 degrees above absolute zero."
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5pvtwx | How exactly did OJ Simpson get a not guilty verdict? The evidence seemed insurmountable | Other | explainlikeimfive | {
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"In fact, the evidence was pretty shaky. The two main items of evidence were the testimony of Det. Furman, who the defense successfully impeached as racist, maybe racist enough to frame Simpson. (Probably Furman was just garden-variety sorta prejudiced, but he was prepared very poorly to field questions about it.) Then there was the DNA, but the defense also showed that the county's tracking and recordkeeping procedures with evidence were lax, so if Furman really were intent on framing Simpson, it would have been possible for him to adulterate the sample. Therefore, both major planks of the prosecution's case were questionable. Then, the prosecution relied on Simpson, an experienced actor, to try on the gloves and surprise, surprise, they didn't fit. (Which is why you never let the other side control one of the main elements of your case.) Normally in L.A. County, when a big black dude was accused of killing a white woman, the prosecutors knew it would be an easy conviction to get, especially from a mostly white jury. And so they did a shitty job of building their case. But this particular big black dude was rich, famous, and charismatic, and so he was able to put them to the test in a way most defendants weren't, and they had no capacity to respond. I would imagine that every single member of the jury in that case thought Simpson had probably done it. But after the defense poked holes you could drive a truck through in all the County's evidence, there is no way the jury could vote to convinct consistent with their oath to find guilt \"beyond a reasonable doubt.\" Because it wasn't likely that Furman manufactured to whole thing, but he was so badly impeached, it was certainly possible. Edit: typos",
"I think the prosecution made a major strategic error. They tried to make it a physical evidence case and put the vast majority of their effort in that. Cochran wisely made it a credibility case and (I think) successfully) portrayed the police as racists and out to get Simpson. Then when the prosecutorial team stupidly had Simpson put on a leather glove misshapen by being soaked in blood, and it naturally did not easily fit, that just played into the racist narrative and severely damaged the physical evidence strategy as well. Probably because the case became racially charged, Many jurors also later expressed fear for themselves if they returned a guilty verdict. It's worth noting that this was not too many years after the Rodney King incident and the later riots, in a large part caused by racial tensions. My personal opinion is that Simpson was definitely guilty. There was a lot of good evidence, not the least of which was Simpson's history of obsession and domestic abuse. EDIT: Changed Reginald Denny with Rodney King. Thanks ostermei! Sorry for the error.",
"You had a high profile black defendant and a mostly black jury. Also, LA was stil having race problems after the Rodney King incident. This verdict was seen as \"payback\" to the white community by most blacks.",
"OJ had great attorneys. Many elements of the evidence were flawed. After Furman appeared to lie on the stand, everything fell into place. If a person lies about one thing, everything he says or does is suspect. Even OJ was shocked at his acquittal though.",
"Bill Maher line from the time, \"The LAPD is so incompetent that they can't frame a guilty man.\" I'm one of the people who think that OJ did it **and** the verdict was correct. The State simply failed to demonstrate in court that he was guilty beyond a reasonable doubt. They mishandled the case as well as mishandling the evidence. The details that convinced me are things that were not presented in court. And the police misbehavior was enough to support reasonable doubt.",
"The short version is that to be convicted, you need to be convinced \"beyond a reasonable doubt.\" Even if there is strong evidence, if the case is not made well, or if there is not faith in the strength of the evidence, that can undermine the verdict. In addition, things like police or investigators mishandling or making assumptions can damage the case. In the Simpson case, despite the evidence, the defense was able to convince the jury that there was enough reasonable doubt in the strength of the case presented and the evidence gathered that it was not enough to convict Simpson.",
"There are a lot of reasons. One is that DNA evidence was new at the time, and the prosecution did a poor job of explaining it. So the defense made up some bullshit about it being contaminated and tampered with so the jury ignored that evidence. Another big piece was the defenses claim that OJ was framed. The jury was almost entirely minority, so this argument had a lot of weight with them, and again the prosecution did a very poor job of explaining why it was impossible for this evidence to be planted. As far as the jury was concerned, all the evidence could be explained by the police framing Simpson, and there was no reason to believe this was an unreasonable explanation, so that gave them enough doubt to find him not guilty."
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5pvyck | What is a Health Savings Account? | Economics | explainlikeimfive | {
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"Money is deducted from your paycheck and placed into an account that is to be used only for medical expenses. The advantage is that you don't pay taxes on that money. For example, let's say your paycheck is $1000 and you pay 30% in taxes. If you don't contribute any money to your HSA, then you pay a total of $300 in taxes. $700 is in your pocket and that's your money to do with as you please. If your paycheck is $1000 and you contribute $200 to your HSA, then you are only taxed on the remaining $800. You pay $240 in taxes. You have $560 in your pocket to do with as you please plus a savings account with $200 in it earmarked for health expenses. Your HSA works pretty much just like a bank account works. You'll get a debit card for it that looks and behaves just like a regular debit card. (My HSA card is MasterCard.) Anytime you pay a medical expense, just use that card instead of your regular one. EDIT1: Cleaned up a few minor words so I don't look like a dumb-dumb. EDIT2: Your HSA card behaves like a debit card."
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5pw1dw | Why does Rorschach hate Veidt's Plan while likes Truman's Hiroshima Bombing? | Other | explainlikeimfive | {
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"Hiroshima's bombing has very few similarities with Veidt's plan at all. Hiroshima's bombing was done to end a war between two nations, and was exactly what it seemed to be: a strike used to end a war. Veidt *purposefully* caused disasters and pinned them on someone else in order to get people to unite against that \"common foe\" (which wasn't a foe at all). It was basically a trick. Rorschach doesn't think the deception is worth it."
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5pw2zt | Why do we pee our beds as kids, but not as adults? | Is there a process in our brains that stops us from peeing the bed which didn't happen when we were kids? | Biology | explainlikeimfive | {
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"- Your body learns to control its bladder - Your body learns to respond to signals of the bladder At first you wear diapers, so your body doesn't have to learn, but once you take those off, your body will slowly learn to control the bladder muscles as well as signal your brain that it's time to wake up and go pee"
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5pw3fq | Why are US congress member's allowed to retain their private careers and other outside business interests while serving the government? | Other | explainlikeimfive | {
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"Once upon a time, citizens were expected to return to their lives and careers after serving in Congress. The same with Presidents. Many were lawyers, merchants, craftsmen, farmers, and all had means outside of government. They were given a stipend for their service but not a salary.",
"Private careers and outside business interests are two very different things. Federal Legisllators don't typically maintain a second job outside of their legislator job, because they simply don't have enough time to do both. However they would retain any licenses they have, like a law license for example. In terms of business interests, this primarily means investments. As long as they aren't using their power to improve the outlook of their investments, it's not a conflict of interest.",
"Because the constitution doesn't say they have to give them up. And the Supreme Court hasn't ruled that it's a conflict of interest.",
"It would be a matter for the ethics committee, notice the first thing the GOP did after the election was to try and get rid of the ethics committee? URL_0 ."
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5pw73n | Why does honey sometimes crystallise and go 'hard' in the jar? | Biology | explainlikeimfive | {
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"Honey is highly concentrated solution of sugar. We don't actually see or feel the sugar at first since it is dissolved in the honey. IIRC, the liquid in the honey gradually becomes over-saturated, causing the sugar particles to separate from the liquid and clump together. This is what creates the \"hard\" texture of the honey.",
"Honey bought in stores is about 70% sugar and 20% water with 10% other various chemicals. This high concentration of sugar doesn't occur naturally and the honey is unstable. The sugar is oversaturated and the two major types of sugar in honey (Fructose and Glucose) start to clump up and crystallise. How fast it crystallises depends on how much fructose there is relative to glucose. [Bee Raw, a little more technical explanation if you're curious]( URL_0 )"
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5pwcnl | Why does a flight from London to Italy(2500km) cost about $70...but a flight from New York to Atlanta(800km) costs about $250 ? | Economics | explainlikeimfive | {
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"The answer is actually *really* neat! In addition to overhead costs in the US being generally higher, airlines in Europe (due to the way the EU handles borders) are generally cheaper. Airlines which are based in a country generally have to pay different fees to different countries for air-traffic-control services, so as a result the first instinct is to think that London to Italy would cost *more*. But, the EU treats airlines from all member countries as domestic. This helps *immensely* without travel costs because it expands the negotiating powers of budget airlines in member countries. But, since both flights you mentioned are treated as domestic that's not a factor in the answer. *** Given the lack of information on airlines and airports, I'm going to assume you're talking about RyanAir in the UK taking off out of Stansted and flying to Pisa. RyanAir has extremely low overhead costs relative to other airlines simply based on their purchasing and employment choices, however they use a secret weapon for budget flights: using smaller, more remote airports. Stansted is a small airport about a 40 minute train ride outside of London, so RyanAir is able to negotiate much more favorable prices in take off and landing fees simply by bringing business to the airport. And while Pisa is a larger airport, they're able to offer cheaper prices by keeping the runways in use during slow times of day. If you'd like more information on budget airlines, check out [[this video]]( URL_0 ). *** So, why doesn't this work in the US? Increased costs following 9/11 have been cited, and this is true... But it's not the whole story. Budget airlines in the US have rarely been successful. ~~, and lately they're being executed incorrectly. Many of the current \"budget\" airlines in the US are subsidiaries of larger airlines, which means that their costs/profit margins are supposed to be high... But their big-ticket airline managers are executing the budgeting and negotiating incorrectly.~~ Additionally, there are simply fewer cheap airports in the US. In the end, US-based budget airlines just don't have the playing field to run well ~~and aren't executed properly.~~ *** Update: apparently my information about airline-within-an-airline schemes was dated, so I've struck it out of the answer. Update2: People are asking about Brexit in relation to air travel. I don't really know much about how this will affect air travel between the UK and the EU, but air travel between other EU states and between EU states and international destinations shouldn't change much. From the US to EU states, there are many airports in Ireland that can be used instead of UK airports so those costs likely won't change by much after Brexit.",
"Do you mean $70 for a budget airline like RyanAir? A fair comparison would be Frontier Airlines, who offers round-trip flights from LGA (NY) to ATL frequently at $60 roundtrip. I've similarly gone from Philadelphia to St. Augustine (880miles), Minneapolis (1,172miles), and Raeligh (471miles) for $30-$60 through Frontier. ELI5: you're comparing a budget airline to major US carriers. There's often a discrepancy, but I've taken similarly expensive flights in the EU. Budget prices exist in the US, but people often complain about amenities being taken away despite seeking lower fares.",
"The price you've quoted for the London to Italy flight comes with several strings attached - flying from smaller airports outside the city (airlines save on airport tax), weird takeoff and landing times (again, to save on taxes by utilizing undesirable times). Also, the price quoted is pretty much $2-$3 for the actual ticket itself + taxes. The airline is not making any money on you (yet!). Real income comes with all the additions you need - check in at the airport (fee), print a boarding pass at the airport (fee), take a carry on with you (fee), check in a bag (fee), choosing your own seat (fee), drinks (fee), snacks (fee), etc. Buying a ticket on a major airline to fly between to major cities comes with its perks. All 3 airports in NYC (JFK, LGA and EWR) and the airport in Atlanta (ATL) are all Delta hubs (3rd largest airline in the world). Hub to hub flying is always a little more expensive, not to mention direct flying. Hub to hub because anywhere from 40% to 99% of the flight could he connecting (I work for Delta, worked a flight a few days ago from Salt Lake city to Atlanta with 99% of the people connecting), mostly international; airlines like to keep these flights for people who are going onwards or are willing to pay extra. Direct because it's a luxury getting to your destination quicker, and luxuries often come with a surcharge. Now, if you were to go on the same route but were to do LGA to DCA to ATL, your ticket would be cheaper because you're not taking a valuable seat on a direct flight, and don't kind getting to your destination in 5 hours rather than 3. And, flying on big name airlines also come with added benefits. On international flights, they almost always serve free meals. On long haul international flights with Delta, even booze is free. Also, flying with a major airline comes with their name, and what it stands for. Delta prides itself on being the #1 on time airline in the US, and also the airline with the fewest cancelations. If you're an occasional flyer, this won't matter to you that much. But if you're a business traveller, then an airline can use this title to capture your business travel needs because it's offering you something no other could. That gives the airlines the right to jack up prices even further. tl;dr budget airlines can offer cheap tickets, but they come with many inconveniences. Major airlines charge more, but comes with more peace of mind. Flying hub to hub is expensive because of mostly connections.",
"I work in Aberdeen Scotland, the flight home (250 miles MAX) costs £250 I have a spanish colleague who flies from Aberdeen to Malaga Spain(1920 miles) at the price of £15! Airlines and supply and demand normally dictate the price.",
"What I want to know is why it costs $900 to fly from Toronto to Vancouver, and only $300 to fly from Toronto to London, Heathrow on Air Canada. I understand costs are higher in Canada but it is the same airline, they use more fuel going to London, so where is the money going?",
"public transportation is a thing in Europe unlike most of the states. trains run across Europe more effectively and provide serious competition to air travel. trains in the states are no where near Europe's quality and will never compete. I also believe the majority owners of travel companies own airlines and the trains allowing them to price inflate. there are issues in reference to price fixing, but when have we actually punished white collar crimes in this country.",
"If you think airfare is high in the US, try flying in Canada. Vancouver to Toronto (equiv Seattle to NYC) is at least $700. Flying Comox to St. John's, pretty much as far W/E you can go in Canada, is more expensive than flying to Australia.",
"A lot of people have given good answers citing supply and demand, I just wanted to add that your numbers seem wonky to me. According to Wolfram Alpha, New York to Atlanta is 1200 km and London to Rome is about 1450 km which is a HUGE difference between the numbers you put here. Also, URL_0 has flights to Atlanta for $117. And flying to Miami (even further away) went as low as $77. So maybe the ELI5 is that there isn't really that much of a difference after all, and it's all just perception.",
"I just came home from London with my fiancee last weekend. Travelling costs were(for each person): 40 minutes drive to Basel Airport from Freiburg via shuttle bus: 20 Euros Flight to London Stansted, with priority boarding, no checked bags: 27 Euros 40 minutes drive from airport to King's X via bus: 12 pounds Return bus to Stansted: 12 pounds Flight back home: no idea, the 27 euros for the flight to London covered the flight back home as well. Bus back home to Freiburg from Basel: 20 Euros So the flight two ways was cheaper than transportation to the airports EACH. Weird world.",
"Fun fact: A flight coast to coast in Canada in coach/economy is often more expensive than international flights.",
"One of the biggest reasons is the prevalence of budget airlines like Ryan Air in Europe. Google Flights shows a London -- > Rome departure tomorrow for us$36. However, having flown Ryan Air, I can tell you you get what you pay for. And that price is only realistic if you do everything self serve and have only a small carry-on bag. Check in online? That's free. Check in at the airport? They will charge you £50. Bag fees are similar to North American airlines if you pre-book that online, but if you are overweight or the overhead bins are full, Ryan Air will either reject your luggage or force you to pay £30-£125 depending on weight. And then the entire god damned flight is nothing but sales pitches. Major airlines will try to sell you food and drink. Ryan Air will push that harder. And, hilariously, will try to force things like lottery tickets on you too. And the plane... you know that \"Super Nintendo yellow\" colour you got after the console was about 15 years old? Yeah. The plane I flew in was probably the exact same plane Air Canada flew in the early 1990s. Discount airlines are trying to make a go in North America. ~~Sprint~~ Spirit is notable in the US. NewLeaf is trying in Canada, though they have run into some issues where an incumbent airline will match their route and prices until driven out. Now, what I would like someone to explain is why it costs me 60% more to fly from Calgary to Toronto direct than it does to fly from Calgary to Detroit *via* Toronto. That's the baffling one.",
"Demand plays part in the role. Flights between two major cities (such as NYC and ATL, which are both regional airline hubs and buisness centers) are typically expensive because airlines know those routes will be heavily utilized no matter what, and charging a bit more could mean extra profit.",
"We have a more developed low-cost-carrier (LCC) market. I think this is mostly demand driven. Europeans travel more for leisure and leisure travel would be more price-elastic than business travel. Thus cost and cost-cutting is much more important. We probably also have a somewhat more robust lower-middle class. Who in any case travel a lot more for leisure than Americans. It's perfectly normal for poorer Europeans to spend holidays in Spain or even go for the odd package-skiing holiday. Of course they will only buy the cheaper options and can be more flexible in their planning and time than business travelers. Which allows carriers to lower costs by flying to airports with low fees and utilizing otherwise unattractive flight times to lower costs.",
"Guys the answer is simple I don't know why everyone is looking for such in depth reasons. It's because ever since deregulation of the EU air travel market, competition has been fierce on many routes - in comparison consolidation and mergers between US airlines in the last 15 years has left many routes suffering from oligopoly and a lack of competition.",
"In Europe we have this fency public transportation called \"train\" which is competing with airlines biggly. So true. (Approved by DJT)",
"Very simple: Americans are willing to pay too much, so the airlines will keep charging too much",
"Mind also that a flight from Italy to Italy (about 800km) is also ~250 euros, so I think it depends on the companies",
"Wendover productions did two very good videos, the first one ( URL_1 ) breaks down costs for a flight similar to Atlanta New York) while the second one explains how low budget airlines manage to cut down on those costs ( URL_0 )",
"You think the price of flights are terrible, the price for a flight from Baker Lake, Nunavut (where I'm from) to Winnipeg, Manitoba is approximately $2,000. The airlines here love to fuck us over, we're basically stuck living here, not a lot of people are rich",
"I have to say, in the last year I've flown from the UK to France, Italy and Hungary with budget airlines. The flights were always between £200-300 (return). Prices like $70 do happen but it's the exception, not the rule. It's probably off-peak season, flying at awkward hours (arriving after the last public transport finishes) and at a remote airport. Normal budget airline prices are probably closer to what you guys see in the US.",
"simplest answer is it doesn't depend on what the costs are. it depends on what people are willing to pay.",
"The airline prices skyrocketed in the U.S because of post 9/11 fear and companies fixing prices",
"We can pay as little as 10€ for Italy-London. Enjoy your amazing land of the \"free\" and the \"brave\".",
"That's great and all but how and about explaining the above points. American doesn't need yet another no-frills discount carrier. BTW Europe has bigger Unions and more regulations and employee benefits than America.",
"I'm Spanish and almost each week have to fly to different European cities, for example this month I have fly from Madrid to Milan, Warsaw and Munich. Prices in this order: 144, 89 and 125. Iberia, airBerlin and Ryanair",
"Cut price carriers carry more freight, hence the baggage restrictions. Then there's things like subsidies, reduced fees/taxes in the EU ... the benefits of which we may or may not loose when the UK leaves. Edit: And filling the plane.",
"~~Transatlantic flight has to carry enough fuel to be able to reach emergency landing sites, which are fewer transatlantically than on the European continent.~~ ~~Also, European flights need to be priced competitive compared to rail travel. There is no such competing rail travel for transatlantic travel.~~ Edit: nvm",
"I took Ryan air to Stockholm from Berlin. Saved a metric shit ton of money. But I didn't research where the flight landed. After I got through customs, I had to buy a fucking bus ticket to Stockholm proper. It was nearly 90 minutes with traffic. I wish I took an actual airline that time.",
"I don't think the distance (ie fuel needed to get there) is the huge factor, A lot of it comes to the tariffs airlines pay to land their planes at the airports. In Europe a lot of the cheaper flights are due to flying from and to obscure smaller airports as opposed to flying JFK to Atlanta which are busy airports.",
"Some airports in the US has exclusivity deals, in which only one company is allowed to fly from that airport to certain areas. That can also inflate the prices quite a bit in the US. From my understanding in the EU is it a lot less common to happen, which is why in EU flights, it cost a lot less, because competition is higher. But of course it also depends on the amount of people and amount of flights. If there are many flights from london to italy (several a day), it can cause less overhead, while if there are less flights and maybe some flights leave without a full plain, they increase the price to cover some of those losses.",
"Well, there are cheaper airlines in the US too, but they are not nearly as popular. I think a big reason is that, in order to make tickets cheaper, they pack the seats tighter, and Americans are less likely to go for that. Another reason those flights are so cheap, is that you get one personal item, and that's it. You pay extra for a carry on, and/or each checked bag. I think another reason that sort of airline hasn't really taken oof in the US is because the cities are so far apart. You can fly practically from one end of Europe to the other in 2 hours. It takes more like 5 from, say, DC to LA. 2 hours packed in isn't bad, but 5 starts getting really lengthy...",
"This needs some real freakonomics applied. Take data from thousands of tickets then correct for miles flown, type aircraft (fuel economy is huge), correct ticket price for a baseline service like 1 carryon and 1 checked bag, and some other factors that can majorly skew the data. Then you can examine which outside factors impact ticket price the most be it taxes, fees, wind, market. It may be more interesting to examine if it's cheaper to generally fly east or west and if this is continent, hemispherical, or global. It's faster to fly east across the Atlantic than west due to the jet stream and pilots constantly battle to grab this contested altitude at the tropopause. Also because of its ideal combo of low temperature and high air pressure. The reason we don't fly higher is temperature increases as well as pressure dropping until the mesosphere 60km-80km and if you're that high you may as well make a suborbital rocket."
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5pwcsq | What does a virus or bacteria gain from making its host sick? | Biology | explainlikeimfive | {
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"Bacteria and viruses don't necessarily want their host sick, or even dead. Complications happen when the virus is in an organism it's not supposed to be in, and that organism isn't equipped to handle the virus. Rats carried the plague and were doing just fine, but when they jumped shipped and infected humans, they wiped out millions in the 14th century. It's the same with the influenza virus, and other viruses. Their goal is to multiply within their host for a while and then spread. Sometimes though, killing your host and exposing its fluids to other organisms is the best way to migrate.",
"The same thing people gain from turning a forest into a grassland, or a meadow into a city, or by fouling a river by pooping in the river rather than pooping in the house. Basically, the bacteria or virus doesn't see you as a being, it sees you as terrain. That it hurts you, or provokes an immune response that makes you feel bad, isn't relevant. It's just trying to live, and in living it creates waste product, eats your cells, or interferes with your processes as helps itself.",
"These organisms exists only to replicate and spread. Our bodies fight them, and in the process, we feel \"sick.\" This is our body's response to the fight. Fevers kills bacteria",
"Sometimes making you sick helps the illness to reproduce. Such as making you sneeze and cough to spread infection. Often times it's not intentional. Diseases that are new to a host often are the most dangerous. They aren't built to infect their new host so they sometimes kill it. In doing so they can actually make it harder for itself to keep living and reproducing. Most illnesses that have been in humans for a LONG LONG TIME are quite benign. For example, humanity has gotten infected multiple times from cross species herpes infections. The type of herpes we've had the longest is almost totally invisible to us. It can infect over half the population and no one has any symptoms at all. The newer forms of herpes are the more obvious and painful ones. The illnesses evolve over time to be less and less harmful and to infect more and more people.",
"It's troubling to think of these viruses as if we were explaining humans and the host as the earth."
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5pwdmf | What is a "sigh," exactly, and why do we do it when we're sad or exasperated? Does every culture sigh? | Biology | explainlikeimfive | {
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"I don't think it's cultural or even human for that matter. I've heard my dog sigh when he's frustrated",
"There is a great article in the Guardian that discusses this; > Californian scientists have identified the source of the sigh. It is not just a response to sadness, depression or despair: it is, also, they report, a life-sustaining reflex that helps preserve lung function. URL_0 It occurs in humans and animals, so would happen in all cultures.",
"I might have to dig it up somewhere but there was a good response to this question before as it being a kind of \"emotional reset button\"",
"What about sighs of exasperation? They don't seem so... resty to me."
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5pweu1 | There's plenty of cow milk to buy, and some goat milk, but is there's a reason we don't produce and consume milk from other farm animals (like horses, pigs, etc)? What about cheese made from that milk? | I'm guessing maybe it's because these animals don't produce nearly as much milk to make production viable, or because it tastes nasty to us? | Biology | explainlikeimfive | {
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"Humans domesticated cows and have been selectively breeding them for milk production (among other things) for so many generations that they're in no way similar to their wild ancestors (who have been extinct for centuries by the way). So they basically kind of fell into that niche - it basically became *easy*. That said, as you mention, goat milk/cheese are fairly popular, as is sheep milk cheese. Water buffalo is also fairly common (it's what mozzarella, for example, is supposed to be made from). Horse and camel milk are also common in certain areas of the world."
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5pwgfp | Why are Americans so worried about losing jobs to other countries when their unemployment is at 4.5%? | Other | explainlikeimfive | {
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"I think the real fear is losing skilled jobs. Yes, our unemployment rate is 4.7%. However, our underemployment rate is 13.7%. The last decade has produced significant increases to costs of living (home/rent costs, insurance, tuition). During this time, many skilled jobs have been outsourced to citizens of other countries who are willing and able to work for less than the average American worker can afford. Many people who have lost their skilled jobs have turned to other less skilled forms of employment as an interim solution until they find another skilled position. The problem is that the skilled positions continue to leave the country. If prices keep increasing like they are and our average salary's and work opportunities continue to decrease, you start to think about a dystopian future of a country full of Uber drivers and fast food workers, being ruled by the \"1%\".",
"A lot of it has to do with the government changing the definition of \"unemployed\". Basically, everyone considers a person with a 40 hour/week job as employed, but the US government expanded the definition to anyone who is employed either part time, full time (40 hour/week), or someone who has been out of work for over 6 months or 1 year (I forget which one it is, but it's either 6 months or 1 year). The reason is that people with 40 hour/week jobs are properly marked as employed. Part time employees had their status redefined. There is a second part to this though, because some people work more than 1 part time job to make their living, so that skews the numbers as well. The people who have been unemployed for longer than 6 months or 1 year are also removed from the unemployment status because they are considered \"no longer looking for work\", even though there are some that likely may still be looking for work. So when you break down the numbers, say there are 1,000 jobs. 600 people have full time jobs, 200 are working part time jobs, 100 are recently unemployed and 100 are long term unemployed. This means that 600 full timers have 600 jobs and 200 part timers may be working between 200 and 400 part time jobs. Even though there are \"technically\" 200 people in that scenario that are unemployed, if 200 people are working multiple part time jobs, the unemployment rate would be 0% because there are 1000 jobs and \"technically\" 1000 employees. That's the problem. The number is manipulated to look better. So if you see 4%, there is a legitimate possibility that it could be 10% or more. Sorry for the long response, but with US labor designations, there is no easy explanation. I hope this helped clear it up a bit?",
"First thing is that the unemployment rate doesn't include people who gave up looking for jobs or people that are looking without the help of the Workforce Commissions or other unemployment services. Secondly, if jobs move from America to Mexico (for example), then it means less people employed here in America. No one really has a problem with a company opening a *second* plant in Mexico, especially if that plant is focusing on making products *for* Mexico. It helps build their economy using their own resources. But when an American plant closes down in favor of a Mexican plant making products for America, then not only do Americans get put out of work, but more money flows from America to Mexico, bolstering their economy at the expense of our own.",
"That number is an intellectual lie. There are plenty of unemployed and underemployed in the US, as well the low skilled, low pay and seasonal work make up a disproportionate amount of the employment numbers.",
"You already have other excellent answers, but also note that unemployment varies by industry. Nurses aren't particularly worried about losing their jobs, factory workers are."
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5pwivc | How do eyeglasses fix our vision? | Other | explainlikeimfive | {
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"They transform the focus point of light so that it focuses on your retina instead of behind or in front of it. Bad vision just means your eye shape isn't perfectly focusing the light on your retina, so the glasses pre-adjust the light for your eye."
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5pwk1g | Why does it take so long for death row inmates to be executed? | Other | explainlikeimfive | {
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"Basically, we have to have a certain amount of process and double-checking and appeals before it's acceptable to kill someone. Let's say you get wrongly accused of a crime. One that carries the death sentence. I don't imagine you'd be cool with the sheriff executing you on the spot. You'd want a trial, a lawyer, plead you case, argue that the circumstances that make you look guilty are a coincidence. That's how a normal crime works. And if the system screws up and puts an innocent person in prison ([which it does]( URL_0 )) they have a chance to fix it and get set free. Like if something changes. Like DNA testing gets invented. Stuff like that. Death is hard to undo though. And they've killed innocent people that have been exonerated after the fact. So there's some extra process to make sure that doesn't happen that often. The question is, how much effort would you be ok with people expending and still wrongly executing you?"
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5pwl2h | How does the UK justify that they have a reasonable claim over the Falkland Islands? | Other | explainlikeimfive | {
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"> But how does the UK justify that they have a reasonable claim over this territory? Is it simple as 'we were here first'? Less of 'we were here first' and more of 'our people have been here for a while now, so it's ours.' Control of the Falklands basically relies on alternative colonialist and imperialist ideas. The Argentinians believe it should be theirs because of the Papal Bull that basically gave South America to the Spanish (so, they inherit the Falklands from Spain's Empire). The British say it's theirs because they took it in 1833 and no one stopped them, mainly because Spain completely abandoned the islands in the early 19th century. The UK populated them with settlers, and the descendants of those settlers overwhelmingly support remaining within the UK. Furthermore, there is absolutely no evidence to suggest that the Falklands have ever been populated by humans, except through various settlement attempts from European nations. The British keep it because their attempt was the only successful one.",
"They weren't actually there first, New Spain was, then they withdrew from it during the peninsular war, which resulted in it going to British hands. The claim is strengthened by the fact that Falklanders overwhelmingly wish to be British instead of Argentinian, and Britain's military might further strengthens the claim.",
"The British settled there. So the inhabitants of the islands are of British decent and want to be under the British crown.",
"Strategically they hold almost no significance, although oil may change that. At the time of discovery they were uninhabited and there was no official claim to the territory. It's now a case of we have British citizens who live there and they voted in favour of remaining British in a referendum so, the islands will remain British. Just because an island is close to your country, doesn't mean you can stake a claim to it.",
"Because the people who live there want them to. It's the same logic used to justify pretty much every legitimate claim. When asked, the people of the Falklands say that they are British and that they want to remain that way. When asked if they would like to be ruled by Argentina they decline. But even if they weren't part of Britain, that wouldn't mean they default to being Argentinian. It's an island far outside Argentinian coastal waters with it's own distinct history, culture and ethnicity. They would default to being their own independent state. Argentina is trying the same imperialist bullshit that Britain tried in Ireland, or Japan in South Korea. \"It's near, it's smaller, therefore it is mine\". When has that ever ended well? The fact that the people live on an island makes absolutely no difference in that regard. From the early 20th Century onwards we've been using self determination as the basis for legitimate claims of sovereignty and the people of the Falklands have spoken unequivocally in that regard. Arcane historical claims are not, nor have ever been, a reasonable justification for war. Geographic proximity (or in this case non proximity) doesn't even make any sense, Argentina is the same distance from the Falklands as the Falklands is from Argentina, the argument that the Falklands should be ruled by Argentina is the same as the one that Argentina should be ruled by the Falklands. The only thing that matters is what the people say."
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5pwm1n | Why is it colder at higher altitudes even though hot air rises? | Physics | explainlikeimfive | {
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"> Why is it colder at higher altitudes even though hot air rises? Hot air rises, but as it does so it spreads out and by spreading out it cools down again.",
"When sunlight hits the earth, the air absorbs some of the energy and gets warm. The atmosphere at high elevations is thinner, so there is less air to absorb the light, which means it's cooler.",
"Let's say you have two containers that are sealed. One has twice as many atoms or molecules in it than the other. Both containers are the exact same size. The more molecules or atoms you have the more hot they will be. There will be more random collisions between particles. The closer you are to the surface of the earth, the more dense the air is, just like the container with twice as many particles. Someone else also said that there are more air particles near the surface to absorb energy from the sun. I think this is the case as well. Also any energy not absorbed by air particles will be absorbed by the earth's surface. On top of all this the closer you get to space, the harder it is to transfer energy by conduction. Space is very, very cold because heat transfer occurs almost completely by radiation. So the closer you get to the emptiness of space, the colder it is as well. I'm not one hundred percent sure that I am correct. I've taken two physics classes while pursuing my engineering degree but I'm not an expert."
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5pws3l | how do big hotels keep their showers so hot and high pressured? | Currently staying in a big hotel and had a shower thought this morning - how does their system cope with the 8am rush on hot water? Is it an upscaled version of what I have at home or is something special happening? How do they keep the pressure so good - my hotel shower is better than my amazing pressure at home! | Physics | explainlikeimfive | {
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"Large buildings like hotels, high rise condos/apartments, etc have large boilers that can generate massive amounts of hot water and use pumps to supply pressure.",
"For big buildings they use cisterns on the roof to increase pressure. And giant water heaters that refill a lot faster then home units.",
"In-line water heaters are used more commonly nowawadys too. There's never a loss in hot water because it is heated on demand to any temperature you set.",
"The hotter the water is, the less of it you need to make a comfortable shower, percentage-wise. Since there is uneven demand for hot water, and a fixed amount available in the tank, keeping it super hot means more people can take comfortable showers."
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5pwv1s | Given that x-rays have more energy than visible light and radiowaves have less energy than visible light, how come visible light can't penetrate walls but x-rays and radiowaves can? | I have a physics degree, and I have always been worried a 5 year old would ask me this question. | Physics | explainlikeimfive | {
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"This is my understanding (from my sibling who has a physics degree. So, fair warning, I may bring misunderstanding or misexplaining what I was told.) Transparency isn't about a wave being strong enough or fast enough to get through a material. It's more like having the right shape to fit through a space then it is like powering through a barrier. Imagine a hole that looks like a capital B. A capital P could fit in that hole, and go through to the other side. A lowercase b could do the same. But neither a capital S nor a lower case s would fit. Different materials are like different shaped holes, and different wavelengths are like the different letters trying to fit through them. It's not about the speed or the energy (even if shape is related to speed and energy) it's about whether a particular speed or energy fits the particular shape.",
"Well technically, visible light could pass through the walls in your home. It'd just have to be several times brighter than the sun. The answer to your question though, is that radio waves are very large and slow, while gamma waves are very small and fast; these properties essentially means that gamma waves can move past walls by slipping past the subatomic spaces, while radio waves just ignore the walls completely, because they're so large and thin. Visible light on the other hand is in that weird spot where it's neither fast enough, nor large/small enough to ignore the physical properties of the wall. So when photons get exposed to structural elements within a wall, they get scattered. Heck, even the paint on the wall absorbs the photons of the visible light, depending on their vibrational frequency, thus causing even more scattering."
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5pwvdz | If water and ice both have transparent properties, why is snow white? | Physics | explainlikeimfive | {
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"Snow is tiny ice crystals which disperse light. And when you add millions of them together they disperse light in many different directions turning the snow white. The same will happen if you have lots of ice cubes who are transparent individually but when lumped together they become white as well. It's the same principal."
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5pwvwo | Why does a bullet stopped by kevlar do damage, but the recoil from the other end of the gun doesn't even hurt my hand | Physics | explainlikeimfive | {
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"The gun and the grip are designed to apply forces to a part of the body that's pretty sturdy. It would bruise your body if it was resting on your belly. Many folks who are new to shooting fail to hold the butt of the shotgun or rifle firmly to their shoulder. Fearing the recoil, they allow a little gap to form. This means the gun gets a little momentum and makes a sharp impact. This causes a shoulder bruise every time.",
"Theoretically. The amount of force that you feel when you fire a gun is equal to the amount of force you feel when you are hit by a bullet. (Every action has an equal and opposite reaction){I have only fired a gun, never been shot by one. But this is what they say in training} So imagine firing a gun, the force you feel on your hand is spread out over your entire palm and thus is more spread out and less potent. Now imagine that force being squeezed into a small point of a bullet. Maybe a few millimetres. When all that force combined on that small point, it pierces the body and goes through. Now what Kevlar does is stop the bullet using layers of Kevlar fibre sheets. When a bullet hits it, it does not pierce but 'stretches' the fibres spreading the force over a large area thus numbing the impact. Obviously it is not perfect and a shot is likely to leave a bruise. Hope this helps Stay safe",
"Replace gun and bullet with a hammer and a nail. If you hold a block of wood and pound a nail into it, you'd feel the impact but if you hold it correctly it wouldn't hurt. That's what it's like shooting a gun. If you hit a nail directly into your skin, it's going to hurt like hell and possibly kill you if you hit a vital organ or pierce an artery. That's what it's like to get shot without any protection. I can't think of another common material that works well with the hammer/nail analogy besides kevlar, but kevlar works by keeping the bullet from penetrating the skin. You still feel the full force of the bullet but it is spread out over an area of a few square inches rather than the very small tip of the bullet. So instead of getting hit with the pointy end of the nail, it would be more like flipping the nail around and hitting the tip with the head against your skin. It won't penetrate and kill you but it will hurt like hell and leave a nasty bruise. In all those cases, the amount of energy from the hammer hitting the nail is the same. How the energy is transferred into the body is different.",
"When firing, the bullet only transfers momentum (mass*velocity) to you, the shooter, by conservation of momentum. However when it strikes its target , it delivers BOTH momentum and KINETIC ENERGY (mass* velocity*velocity) to the target. via conservation of momentum and conservation of energy. The velocity squared term (and thus the kinetic energy) is extremely significant because of a bullet's high velocity.",
"I'm going to gave you a bowl of ice cream. You get 30 minutes and a spoon to eat it all. Easy right? What if I told you to eat it in 30 seconds? That would suck. A spoon wouldn't do the trick. You'd just end up with the bowl in your face. Ice cream is kinda like energy. There's a bunch of it. You have to eat it. How much time you have to eat it determines how good or bad the experience is going to be. Larger people have more mass for eating more ice cream at once.. Small children can't eat as much before it sucks. When the weapon recoils, you have a bunch of energy. But you have a nice big mass in your gun and your body. You also have a relatively long time to eat all that energy. You can casually rock back over a half second. On the other end there's the same amount of energy. But it has to be eaten like... NOW or else someones gunna die. So kevlar has to eat a lot of energy very very quickly and only has a tiny spot of kevlar and human stuff directly behind it to do that. Which means you're gunna have a bad time, but maybe not as bad as it could have been."
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5pwx90 | If the Keystone Pipeline is approved, but the US withdraws from NAFTA, what will this mean in terms of oil trade through the pipeline? | The oil will obviously be crossing the border, so will it be taxed? Will this mean that Canada will still go ahead with the pipeline if they will suddenly make a lot less money off the oil? | Economics | explainlikeimfive | {
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"Canada already makes a lot less money off our oil, so paying more in taxes would be merely one more expense to consider. WTI crude - the price you see in the papers - is currently trading in the $55 range. Western Canada Select - what we sell to you - is around $38 right now. There are actually several pipelines already running between the two countries. The denial of Keystone XL did not prevent trade, but limited our capacity to ship to US refineries. Even if the US pulls out of NAFTA entirely and if the pre-existing Canada-US Free Trade Agreement doesn't contain provisions regarding the transport of crude oil and natural gas, we aren't going to turn off the taps. Largely because our own oil policy has been tremendously shortsighted and created a situation where most of our product goes south to the US. For this reason, I expect TransCanada Pipelines is likely to go ahead with Keystone XL even if it cost more in the end. Keystone XL (note: there is a different but related pipeline called Keystone that is already in service) gets all of the press, but it is also not the only pipeline in the works. The Line 3 pipeline replacement is a project by Enbridge that will replace and upgrade an existing pipeline to the states. Since it wasn't made into a political issue by American interests, it already received quiet approval by Obama, while Justin Trudeau approved it in Canada a couple months ago. Once that project is complete, the shipping capacity will double. Also, the Canadian government approved the Trans Mountain Pipeline extension that goes west from Alberta to the BC coast at Vancouver, and which will expand our shipping capacity across the Pacific. Unfortunately, the success with which (largely American) groups have had with hamstringing Canada's oil growth via the Keystone example has caused them to double down on trying to halt any and all improvements and expansions - even though the two examples I list are replacements and upgrades of existing pipes. I'm not sure what environmental benefit is gained by forcing the industry to continue to use 50-year-old pipes, but I digress....",
"It just means that the taxes and tariffs for the pipeline/oil will need to be negotiated separately. NAFTA is a framework agreement that makes it easier to trade by not requiring state-to-state level negotiation over every good and service that crosses the border."
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5pwxbq | Why is quartz so useful in making watches? | Technology | explainlikeimfive | {
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"Quartz vibrates when an electric current is passed through it. The watch counts the vibrations and uses it to accurately count seconds.",
"If you put an electric signal into a quartz crystal, it resonates in a very dependable way. Quartz watches contain a tiny [quartz tuning fork]( URL_0 ). The tuning fork is cut to a size where it will vibrate 32,768 (2^15) times per second. That's a high enough frequency that humans can't hear it. The vibrations drive a 15-bit digital counter, which reaches its maximum value exactly once per second, producing the pulse that drives the second hand."
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5pwz3y | Can the POTUS issue Executive Order on withdrawing from NATO? | I'm interested what powers the President of the United States has. Can he single-handedly issue Executive Order to withdraw from the NATO, or perhaps single-handedly issue order to make rules in NATO without any Congress approval? I know the POTUS has pretty broad powers when it comes to foreign policy, but what about different treaties like NATO? Thanks for explaining! | Other | explainlikeimfive | {
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"No. NATO is part of a treaty (the North Atlantic Treaty), and only the Senate can make or break treaties. Withdrawing from any organization that we are members of by treaty, like NATO or the UN, isn't something that the president can do unilaterally."
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5px15l | Why do women's breasts get bigger before they have their period? | Biology | explainlikeimfive | {
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"About a week before a woman's period, her progesterone levels increase which causes the milk ducts to swell. This can also cause benign breast lumps. Women are also more prone to water retention which can cause body-wide swelling and bloating."
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5px2v6 | What is the recent ruling about the UK Parliament and Brexit mean for the people of the UK? | I recently saw this article from the BBC. Call me uneducated but I cannot wrap my head around it. URL_0 | Other | explainlikeimfive | {
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"It doesn't really mean that much to the average person, it still means we are leaving the EU. It's about the formal procedure for withdrawing from the EU. The PM (who essentially is \"the government\" in this context) claimed she has the right to formally start the process of leaving the EU without consulting parliament. Someone challenged this assumption in court, claiming that because leaving the EU removes people's rights, it must be voted on by parliament. In the end the Supreme Court agreed. So this means that there will have to be a vote in parliament before we start leaving the EU. The vote will easily pass as the two main parties have said they will vote for it."
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5px40z | There are a surprising amount of people who believe any moon landings were a hoax. Why can't we use telescopes/powerful cameras to prove there was activity on the moon? | Are there no traces of the landings (flag, residual space ship parts, any other debris) that are visible using a high powered camera or telescope? I know even consumer-grade cameras are getting to be pretty good at taking high res photos from very far. I'm not saying that it is necessary to provide MORE evidence of a moon landing nor do I care to open this thread to a debate, but I am curious if this would be possible and if not, why not? | Technology | explainlikeimfive | {
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"The Lunar Rconnaissance Orbiter took pictures of one of the [Apollo landing sites]( URL_0 ). But to a conspiracy theorist, any contrary evidence is part of the conspiracy.",
"The lunar landers are so small (0.009km wide), and the Moon so far away (380,000km), that no Earth-based telescope can make them out. Not even Hubble. You'd need a *huge* telescope to do it. Like, \"hundreds of meters wide\" big. Or, you could use a camera mounted on a satellite orbiting the Moon, which is what NASA has done (the Lunar Reconnaissance Orbiter), as linked by /u/AzrgExplorers.",
"> Are there no traces of the landings (flag, residual space ship parts, any other debris) that are visible using a high powered camera or telescope? Not from Earth, and even if there were the conspiracy theorists would call it fake. It isn't worth trying.",
"Word is that it's too hard to hold a camera steady while zoomed in that much. I believe it. I tried holding a 72× zoom camera, and that was unwieldy enough with zoom.",
"In a myth busters episode they explained how they left a special reflector that can be detected with a laser. The surface of the moon scatters the laser beam but the reflector can send the beam back and so it can be detected. This was demonstrated on the episode but, again, conspiracy theorists will just think the show was in on it. There is plenty of evidence available for the average person to demonstrate that the Earth is round, but there are plenty that still believe otherwise."
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5px7np | What is Net Neutrality and why is there a lot of controversy surrounding it? | Technology | explainlikeimfive | {
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"Say I run a factory building steel folding chairs. I have my steel imported by rail, on the one rail line that accesses my town. Now, railroads are expensive to lay down, and the ones we have were all built a while ago, and only because the government helped by providing large subsidies and seizing right-of-ways through eminent domain. That means there aren't gonna be any new railways coming into my town any time soon, and the railroad company in my town essentially has a monopoly on railroad traffic for the foreseeable future. Now, there are four steel refineries that I could purchase my steel from, and they all compete on price and quality. The biggest of these companies used to be the best, but it dropped off in quality a long time ago, and it's starting to lose business to its competitors. It has way more money in the bank than the other companies, though, so it hatches a plan. Instead of investing to make its steel better or less expensive, the big company instead pays a giant kickback to the railroad company for an \"exclusive contract,\" which requires that the railroad charge the other steel companies *double* to carry their steel and won't allow them to ship steel on the railroad's express trains. This makes it impossible for the three other companies to compete, and they eventually stop shipping steel to my town. Once that happens, the big company is free to jack up the price on its crappy steel. Many, many years ago, the government recognized that deals like the one between the railroad and the steel refinery are bad for competition and the free market, so they made a rule to prevent it. The government has long required that railroads are a \"common carrier,\" meaning they can't discriminate between customers and have to charge everyone the same for carrying freight. This ensures that, in my case, the market for steel in my town stays competitive and free instead of being taken over by a monopoly. \"Net neutrality\" does the same thing, establishing ISPs as common carriers for Internet data. Like railroads, Internet infrastructure was all laid down years ago with healthy government subsidies, and it's prohibitively expensive for a new company to come in an lay new lines. (RCN has tried to and found it very difficult to make overbuilding profitable.) This means that most localities only have one, maybe two ISPs to choose from, and there won't be any competitors in the near future. Say you're Comcast, the country's largest ISP provider, which also owns the Xfinity cable service brand. Xfinity has a streaming video service, and Comcast would much rather you watch that service (and the advertisements on it) than Netflix. Comcast would very much like to add a surcharge to Netflix data to discourage people from using it, or throttle Netflix transfer speeds so it has a lower resolution than Xfinity streaming. Net neutrality says they can't do so, and have to treat Xfinity and Netflix data the same. This means that Netflix and Xfinity have to compete on price and quality, not just who has a sweetheart deal with the local monopoly provider. Consumer advocates, startups, and smaller companies like net neutrality because it helps keep the Internet a free, competitive marketplace where the best product wins. Incumbent telecom giants hate net neutrality because in a free market, they might lose their position on top, and because they can't squeeze out more money for mediocre products.",
"The idea of Net Neutrality is that all internet traffic has equal access to bandwidth/speeds. Doing away with it would be akin to allowing for highway speed limit signs that read \"Speed Limit: 65, BMW Owners Speed Limit: 85\" if BMW decided to pay for such access as a selling point. Or conversely, it'd be like a state choosing to impose slower speeds against a car maker who jilts them and builds a plant in the neighboring state. On the internet, this could play out with ISPs being able to pick winners and losers by doing something like giving Hulu priority speeds and throttling Netflix, since Comcast owns NBC, which is a partner in Hulu. Or an ISP might speed up load times for right wing news sources while slowing access to left wing sources. The loss of Net Neutrality could mean the uneven flow of information, which goes against the basic beliefs of the internet being open to all.",
"It's the idea that internet service providers won't give priority access (more bandwidth, faster speeds, etc) to domains and sites that pay them premium access fees to do so. Net neutrality = everyone has equal access to the same information superhighway. It's controversial because some companies want to be able to pay more to be more visible, and ISPs want to get their hands on that extra revenue stream. The rest of us want the \"little guys\" to have an equal shot at internet bandwidth and access.",
"Internet access is provided mostly by large cable companies. Comcast, AT & T, Time Warner Cable, Verizon, Century Link, etc... Those companies want to make as much money as they can. They can make more money (on top of subscriber fees) by charging companies money to use bandwidth. Right now, they are required to let all companies use bandwidth and speeds equally, and they aren't allowed to charge extra to a company that uses a lot, like Netflix, or one that competes with their products, like Netflix. Net Neutrality is what requires them to keep bandwidths/speeds the same for all websites. These companies don't like that. They want more money. And they already have a lot of money, so they are pressuring politicians to change the rules to let them charge different users different prices.",
"In a world where you can/have to pay for a faster/bigger line to your customers, companies like Netflix, YouTube etc would have a very hard time if they were starting up new today. Net nutraility ensures that all traffic is treated the same."
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5pxav2 | Why would you ever need to know the anything beyond the 2nd derivative of an equation? | Mathematics | explainlikeimfive | {
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"> U.S. President Richard Nixon, when campaigning for a second term in office announced that the rate of increase of inflation was decreasing, which has been noted as \"the first time a sitting president used the third derivative to advance his case for reelection.\" Since inflation is itself a derivative—the rate at which the purchasing power of money decreases—then the rate of increase of inflation is the derivative of inflation, or the second derivative of the function of purchasing power of money with respect to time. Stating that a function is decreasing is equivalent to stating that its derivative is negative, so Nixon's statement is that the second derivative of inflation—or the third derivative of purchasing power—is negative. Also: > In differential geometry, the torsion of a curve — a fundamental property of curves in three dimensions — is computed using third derivatives of coordinate functions (or the position vector) describing the curve. But yeah, typically you don't *need* to know a third (or further) derivative. But it still *exists*.",
"The third derivative of position is jerk (it's the first derivative of acceleration and the second of velocity). Jerk is important for vehicles that accelerate quickly since you don't want to give anyone whiplash while getting up to speed.",
"If you are using a Taylor Series to do a polynomial approximation of a function near a point and the second-derivative term doesn't give you enough accuracy then the next term involves taking the third derivative. This is sometimes done in practice to simplify calculations very close to surfaces (e.g. boundary layers). It is true that most intuitive physical behavior is described with first and second derivatives. Third-order differential equations are not that common. But my fluid mechanics professor used to say \"derivatives are easy, *integrals* are hard\". So don't sweat the higher order derivatives!"
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5pxbf3 | What causes those random shudders that happen seemingly for no reason? | Other | explainlikeimfive | {
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"I'm not sure if this is what you were looking for, but the reason one might get the chills even though we're not sick is because of either a buildup of dopamine that got released in one go, or a sudden rush of fear. This happens more often when we listen to music or watch movies that we really like. There's no specific genre that triggers the shudders, just as long as the structure of the song/movie leaves room for the element of surprise. In a sad song at one point you might eventually shudder because for a split second fear rushes through your body assuming the pain is real, but then the brain realizes it's just fiction, and halts the reaction."
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5pxbgj | when muscles get stronger they grow. How do our lungs get stronger if you go for a long run? | Biology | explainlikeimfive | {
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"Your lungs aren't actually a muscle. They themselves can't get stronger, because they're not the thing providing the power to breathe. You breathe with a muscle called your *diaphragm*. It's a sheet of muscle that separates your chest from your belly. When it contracts, it moves downwards. This increases the pressure in your belly and decreases the pressure in your chest. As the pressure in your chest decreases, air rushes in from your nose/mouth and inflates your lungs, like two little balloons. To breathe out, the diaphragm relaxes, moving back upwards. This increases the pressure in your chest again, squeezing the air out of your lungs back up your windpipe and out your mouth/nose. Your lungs never actually do any work; they only ever \"get inflated\" and \"get deflated\". When you go for a long run, you're strengthening your diaphragm.",
"They don't particularly get stronger. You just increase the efficiency of your body. So much so that you can better process's oxygen. When you get fitter, your heart doesn't need to work as hard to pump blood around your body, so that is more efficient. Your muscles get stronger so exercise gets easier, which in turn makes breathing easier as you don't need as much oxygen. Have a look at VO2Max. It's the efficiency of your heart/lungs."
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5pxc6x | One way mirrors | Other | explainlikeimfive | {
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"text": [
"It is just a piece of glass with a very heavy tint on it. On one side, the lights are off. On the other side, the lights are on and very bright. Those on the dark side can clearly see in to the lit room; those in the lit room can only see glare and reflections off the glass and can't see in the dark room. If you turn off the lights in both room, the glass just looks dark. If you turn on a light in the previously dark room, you'll se able to see in to it from the formerly lit room."
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5pxei6 | What makes blue ink more memorable than black ink? | Other | explainlikeimfive | {
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"Our minds ignore what we deem to be expected and predictable information. It's the same reason why you can often drive an entire commute and not remember the drive when you get home: your brain immediately forgets the routine stuff that you see every day. Blue ink is different than black (which you see 99% of the time); your brain makes a mental note of the difference."
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5pxfou | Why can't touchscreens recognize a touch while a finger is being held on it in another location? | My toddler plays a learning game on my touchscreen phone but he doesn't understand that when he holds the phone (with this thumb touching the screen) he can't touch anything else on the screen. I cannot get him to move his thumb because otherwise he will not be able to hold onto the phone. | Technology | explainlikeimfive | {
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"text": [
"It's not that the touch screen can't recognize the touch, it's that it doesn't know which one to pay attention to. It doesn't want to randomly click things if you grab the phone with your whole hand or if you touch something on the side of the screen with the hand holding it. Basically it's designed to be conservative and safe otherwise people would be accidentally clicking things all the time. My toddler had the same problem. Our solution was to get him his own tablet with a big thick rubbery case. When playing with our phones we put it on a hard surface like a table and tell him he can only touch it with one hand. It's a new life skill. If the game is fun enough, he'll learn soon enough!"
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5pxgiy | Why is it important to preheat the oven before you cook? | Other | explainlikeimfive | {
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"Every oven is different, some ovens might be able to get to 400 degrees in 5 minutes, and some might take 20 minutes. Or maybe you just made a batch of cookies and your oven is already hot. If you just put your food in the oven for X minutes, it would come out differently depending on how long it took your oven to reach the correct temperature. If you pre-heat your oven, then it should come out the same no matter how long it took to preheat. If you know your oven well, you can often get away with not pre-heating by adjusting the cooking time."
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5pxgth | How does rolling upon impact with the ground after a long fall save you from bodily harm? | Physics | explainlikeimfive | {
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"dcuknha"
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"The thing that hurts you in a fall is a change in momentum - the sudden shift from \"going down\" to \"completely stopped\" puts a lot of force on your body, which causes injury. But if you roll upon impact, not all of that force is applied straight into your body - you're taking the momentum of you going down and changing it into the momentum of your roll - it's going in a different direction, and it's rotational. Now much less force is going into the impact (the part that hurts!) and much more is going into the direction you're rolling. It's the same reason that parachutists shift their momentum right before hitting ground, and they land running. That downward force would hurt, even with the parachute slowing you down. Changing its direction means that less energy is going downward into bone-breaking force, and more is going into a forward run that you can slow down on your own."
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3
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5pxjm9 | How did universities and hospitals and such charge so little for services in the past and still turn a profit when they struggle today even charging so much? | Economics | explainlikeimfive | {
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"dculwt9",
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"text": [
"Inflation, for one. But also because the systems are rather screwed up. Universities, for one, are responding from a poorly-constructed incentive created by easily-obtained, government backed loans. The more money governments offer to students in the form of loans, the more tuition increases, because now they have a very definite idea of *what* every student can afford, even though, since they're incurring debt, they can't *really* afford it. Hospitals, similarly, have a batshit crazy system of getting compensated for the work they do through insurance. The government, through medicare, usually sets the price standard for procedures. What this does is violate a company (hospital)'s ability to generate the cost of something based on overhead and profit. Most other insurance companies take their compensation queues from medicare, so it all follows. So, say a hip replacement cost a hospital $5,000. That's the amount they calculate it will cost. Medicare says, \"no, we'll pay you $2,000, and that's it\". Well, now that hospital has an issue. They're making a net loss on that procedure, and there's fuck-all they can do about it. To make matters worse, a HUGE percent of hospital staff are administrators and office staff hired *just to deal with the insurance companies and get their money*, which can be a herculean task. All of this further increases their operating expenses, and yet insurance companies will still dictate and set pricing at whatever they feel is appropriate, regardless if that is unfeasible for the hospital or not.",
"University - Really two things. With the rise of government backed loans, you can borrow a basically unlimited sum of money to go a school no matter the cost. Parents are also usually willing to kill themselves financially to get their kids into the best possible school. I had a teacher who was trying to finish his house quickly just to borrow against it to send his daughter to NYU. For the schools, this means that they want to attract the best students (for a number of reasons), but the students aren't cost sensitive at all. So the schools are going to make the school as nice as possible, at whatever the cost. For example, my alma mater had 10 [Bloomberg Terminals]( URL_0 ) each costing about $24k per year, a swimming pool with a high rise diving board, a movie theater, and probably more stuff I don't even know about. This is probably an extreme example, but the point is that there is just no incentive to cut cost. The other story is as states have been trying to reduce their budgets, one was they do it is cut funding for public institutions. Let's say, using your example, your state decides to cut funding to the school and tuition rises to like $500 a semester. Still not terrible, and the state politicians can pat themselves on the back for cutting spending. But the money has to come from somewhere, and the schools had to raise tuition to meet their budgets. Healthcare - This one is super complicated. There's really no one main reason, but lots of little reasons that all work together to form a horrendously expensive system. Here are a few! 1. You can't bargain with your life. If you go to buy, let's say a BMW, and the cost is too much, you go down the street to Honda and settle for an Accord. BMW then has to decide if they want to sell the car at a lower price or not. But if you need bypass surgery, you're going to the best person you can, whatever the cost. A real example is my buddy that uses Epi-pens. There were generics on the market, but some got recalled. You wanna take a chance on the generics to save a couple hundred bucks a year? Mylan knows the answer, and will charge whatever they damn well want until the patent runs out. 2. The American Medical Association represents doctors. They also also sponsor the organization that accredits medical schools. Supply and demand dictates that if there are less doctors, they get paid more. So they keep the medical schools small and are very reluctant to accredit new ones. This is a huge part of why medical schools are almost impossible to get into today, and a lot of people who would be good doctors can't get into med schools because of one C in school or something but the AMA doesn't represent them, it represents people that are already doctors. 3. The uninsured. As I'm sure you're aware, hospitals are required by law to treat you for emergency services regardless of your ability to pay. So when someone is in the emergency room, and can't pay, the hospital absorbs the cost of the treatment. That cost, plus any costs associated with chasing you down to collect your payment, must be absorbed by the hospital and billed to the people that can pay (or billed to your insurance most likely). 3b. The uninsured also have no access to preventative care. An insured person goes to their physical, the doctor finds high blood pressure, tells the patient to eat a few more salads, exercise a bit, and gives them a prescription to help bring it down. An uninsured person doesn't get that, so they walk around like a ticking time bomb until they go into full blown cardiac arrest, then the hospital has to take them for expensive emergency surgeries, then absorbs the cost. There's other problems with healthcare, and I know it's long winded, but as you can see there's no one reason, so there's probably no simple solution. Sorry it's a bit long winded."
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5pxjv4 | Why is it that a 10 minute 720p video I record with my phone is 700mb, yet a 720p 1.5 hour long movie uses less data? | Thank you everyone for your answers. | Technology | explainlikeimfive | {
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"dcul68h"
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"Before movies are distributed, the data gets carefully compressed on full-sized computers that may have spent many minutes or even hours compressing it, after the recording was complete. The result is better compression, hence a smaller total file size."
],
"score": [
7
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5pxn0m | Who physically writes out things like Executive Orders? | There were Executive Orders ready to go on Jan 20th, so they had to have been prepared in advance, right? Who actually writes these out to be signed? | Other | explainlikeimfive | {
"a_id": [
"dcum657"
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"text": [
"One of the numerous press or speech secretaries/aids that work at the Whitehouse. There are literally dozens of aids who specialize in writing that do things like this for the President."
],
"score": [
8
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5pxn8c | How can I know if a News Source is biased or providing 'Alternative Facts'? | Other | explainlikeimfive | {
"a_id": [
"dcum5em",
"dcumwzd",
"dcuo5kh"
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"text": [
"All news sources are biased to some degree. The best way to prevent misinformation is to cross reference sources. Try to have 3-5 sources known to disagree with each other and compare their reports. When they agree, you can be reasonably certain they are reporting honestly on that fact. It is especially important that at least 1-2 of those sources be ones that disagree with your personal viewpoint. It is too easy to be convinced that what you already agree with is true. You must have some input from \"the other side\" if you want to hope for a reasonably unbiased opinion.",
"All news is biased. OK? That's the plain fact. Humans wrote it. There's billions of events happening right now; a news source has to decide *what*, exactly, they're going to write about, and that very decision is, in itself, evidence of \"bias.\" But bias itself isn't inherently reason to dismiss the news source. Just like any paper you wrote in college, look for *where* the article got its facts. For example, outlets like CNN and Fox are usually re-reporting on news published by the Associated Press. So go there, and read *that* article. If the news article is about a scientific discovery, find the *journal article published by the actual scientists* and read that article. If it is about statistics (for example, 1-in-5 people think oranges are gross), find out *where* that statistic is being reported. In today's day and age, you have to be a meta-journalist. Which is hard, but doing so is rewarding and will make you 10x more informed than the average reader. Publications like The Wall Street Journal, The Guardian, The Atlantic, Vox, all have their leanings, slightly liberal in most cases, but they do solid journalistic reporting with sound facts. The Guardian broke the Panama Papers in a *massive* effort of collaboration with 400 other news sources around the world, which clearly indicated they weren't after money so much as breaking an important story. Based on that, you can *trust* the articles that they put out on important subjects. Now what they choose to write about may often be more of-interest to liberal leaning readers, but the articles themselves are ethical and properly sourced.",
"They're called news \"stories\" for a reason. Someone is ALWAYS telling a story when they publish. To me, the key is to break the story apart. Separate the verifiable facts from the story being told about them. \"Henry VIII killed his wife this morning because she was being unfaithful.\" is a story. Whether or not he killed her is a verifiable fact. Why he did it is story. Now, that story may be backed up by more verifiable fact, \"Henry VIII killed his wife this morning because she was being unfaithful according to a statement he made this morning.\" In this case, we have a verifiable portion and still some story. We can verify via other sources about whether he killed her, whether he made a statement, what that statement actually was, whether it actually said that he killed her for that reason, etc. We still don't know if that actually WAS why. That's still story, but less of one than the first version. Taking the verifiable portions to other sources is relatively easy. And, once separated from the story, you can much more easily verify those portions. If FOX News and MSNBC both agree on those portions, but tell different stories, the kernel of what happened is in those facts. As you search for the facts themselves instead of the stories told about them, you'll usually get closer to the source. Instead of a story about a reaction to a speech someone gave, you can find video or transcripts of the speech. Instead of clips of the speech, you can see the entire video, complete with context. Over time, if you do this regularly, it becomes second nature. Beyond that, with practice, you'll soon start noticing which sources of news do more story-telling than others and which are almost all verifiable reporting of fact. Bonus: If the pieces that SOUND like verifiable facts come from secret sources or sources you can't check out for yourself, wait. Independent information that either verifies or refutes the secret source is almost always on it's way within the coming days or weeks. Reject the storytelling."
],
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5pxwa5 | How does an air fryer work? | Technology | explainlikeimfive | {
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"dcuoe21"
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"text": [
"It's just a self contained convection oven. It uses fans to circulate the hot air so that it cooks things very evenly. Most ovens are not convection. They have heating elements that heat up the food but might not always do it evenly. A convection oven has a fan in it that moves the air around constantly this helps distribute the heat evenly around the space inside the oven which helps cook the food more evenly. This also cooks faster since it takes less time for each part of the food to reach the required temperature."
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7
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5py3mv | In the age of computers, why do traffic cops take ages to write a traffic ticket by hand? Why not have the system that scans your drivers license and creates a ticket for the next available court date? | Technology | explainlikeimfive | {
"a_id": [
"dcuqhzf",
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"text": [
"Actually, there are some agencies that do just that; however, the underlying need for all of the relevant computer systems to be inter-connected does not exist everywhere.",
"Some do, I know from personal experience the California Highway Patrol has a system and doohickey where your ticket is printed up just like a receipt at a store."
],
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3,
3
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5py78a | The hole in the ozone layer. | 1. What is the ozone layer and what does it do? 2. Is/was there a hole in the ozone layer? 3. What caused the hole to form? 4. If the hole is no longer there, how was it closed? | Other | explainlikeimfive | {
"a_id": [
"dcurho3"
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"text": [
"Ozone has the chemical formula O*_3_*. It is constantly formed in our atmosphere. Ozone absorbs harmful UV light so it reduces the amount that reaches the ground. Hole isn't the best description really, there is a lot less of it over Antarctica and the southern parts of Earth. CFCs (chlorofluorocarbons) can react with ozone and turn it back into molecular oxygen (O*_2_*). These were discontinued but they are still present in the atmosphere. It's still there, but it does appear to be getting better. Come visit New Zealand in summer, you can get sunburn in as little as 20 minutes if you aren't careful. This can largely attributed to the ozone hole."
],
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8
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5pyfqf | If the Earth experienced heating and cooling all the time before humans were around, what triggered the switch to cooling when it got too hot and heating when it got to cold all on its own and why won't that happen with the current climate changes? | I don't know a lot about global climate change but if the planets temperature has fluctuated up and down since forever but never just kept going one direction or the other, shouldn't that same environmental mechanism correct for human interference too at a certain point? | Physics | explainlikeimfive | {
"a_id": [
"dcuub5z",
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"text": [
"Yes and no. The planet does have a natural warming and cooling cycle, but it take place over thousands or tens of thousands of years. At its coolest, ice would cover NYC by hundreds of feet. At its warmest, large portions, even a majority, of the US would be swampland, if not under water completely. It's worth noting here that our models of climate change don't predict things getting this warm any time soon. Currently, we're seeing warming at a level that isn't new. It's just happening in decades instead of millennia. Rapid change brings on all kinds of nasty side effects, as the ecosystem has less time to adapt and evolve to the new environment. The planet can easily handle these fluctuations, and on a geological time scale, is barely a blip on the radar. Humans on the other hand aren't so lucky. Huge portions of or population, like NYC or LA, live in cities built on the waters edge. We rely on crops that need consistent weather from year to year fixed optimal yields. Diseases, and the things that carry them like mosquitoes, are slowed by colder climates, but spread rapidly through warmer climates. We rely on fish in the ocean for 15-20% of our food worldwide. Those fish rely on plankton and microscopic life in the oceans that can't survive warmer or more acidic water. There are plenty of other things like this that'll really suck for humanity. We'll survive, but optimistically it's going to take a lot of sacrifices to accommodate everyone in the global population in the new environment. Pessimistically, there won't be as many of us around to adapt to the world.",
"In the past it did get hotter and colder, but it didn't hew to some particular average. Sometimes it was hot enough that there was no ice even at the poles. It was at one point so cold that glaciers covered the whole planet. And there have been points between. Point being, it's not that there's some system that keeps earth in some particular temperature range, it's that various natural processes have different and sometimes cyclical effects on temperature. The two biggest long term drivers are the sun, which gets steadily warmer over time but also moves though various cycles of strength and weakness and CO2. But other factors can play a role, especially to kick off a change. So, for example, an ice age might start because the sun enters a phase where it is relatively weak, and the continents are arranged in a way that is favorable to glaciers forming and spreading. This leads to a run away effect as the highly reflective ice means even more energy from the sun simply reflects back into space, making the ice age more severe. But, that also means that there are fewer areas with trees or open ocean to absorb the carbon dioxide and other green house gasses from volcanic events, which still occur. Now, over time, the CO2 concentration builds significantly, and when the sun returns to full strength, it's not only warm enough to melt the glaciers, but the extra CO2 means it gets even warmer than before. That in turn leads to some new dynamic, say a proliferation of trees that start to take carbon out of the atmosprerequisite, moving the cycle in the other direction. Also, If you're interested in a good straightforward explanation of climate change basics, checkout the potholer54 climate change series on youtube."
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5pyjim | How are syringe needles made? | How are the "holes" in the syringe needle made so fine? How can they make so many in large quantities for so cheap? | Other | explainlikeimfive | {
"a_id": [
"dcutufo"
],
"text": [
"Take a tube and yank on it. It stretches out to be very thin but the hole in the center doesn't collapse! Do this carefully a bunch of times and you can end up with good thin needles."
],
"score": [
10
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5pytt9 | Who is Ajit Pai and why is he such a threat to net neutrality? | Other | explainlikeimfive | {
"a_id": [
"dcux7qw",
"dcuyyh2"
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"text": [
"The big battle about net neutrality in the US was between the FCC (for neutrality) and the service providers like Verizon and Comcast (against neutrality). Ajit Pai worked as a lawyer for Verizon and he has just been appointed head of the FCC. Don't know if it's fair to call it a conflict of interests, that depends on what exactly FCC's mandate is. But people are assuming that Verizon and Comcast are laughing their heads off.",
"So it's like this: Many of the federal agencies or departments in question do good for the citizens. Many of the cabinet heads being nominated to be the leaders these agencies are people that either are on the opposite side of the citizens or want to either do away with that agency or department. In this case, making someone who worked for an internet provider corporation in charge of the commission that controls internet laws and regulations is probably not going to turn out good for the citizens. Just google conflict of interest. Some fake examples that are scary accurate: -Nominating Darth Vader as Secretary of the Jedi -Nominating El Chapo as the head of ATF -Nominating Wylie E Coyote as head of the Department of Roadrunner Conservation -Nominating Rick Perry (someone who said he wanted to eliminate the Department of Energy) as the head of the Department of Energy (oh wait, this one is real)"
],
"score": [
5,
5
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5pyu7o | If I eat 50 twizzlers in one sitting, will the effect be the same as if I ate the 50 twizzlers over 3 days (assuming everything else is constant) | Other | explainlikeimfive | {
"a_id": [
"dcuwx5b"
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"text": [
"It really depends on how long of a time frame you are looking at after you eat them. The only thing that matters in gaining or losing weight is caloric intake vs calories burned. If you ate 50 twizzlers in one sitting and then for the next 2 months, had a very normal diet and excersize, then you will probably not notice a difference in anything. If you ate 50 twizzlers in one sitting and your look at it 1 day later, then most likely you will not have burned the excess calories that those 50 twizzlers amounted to. When you eat food, your body will use that energy before using the energy in yourself (fat and muscle), because the food energy is readily available. If you are looking at both scenarios from just 3 days, then not much will change because in your theoretical scenario the calorie intake vs calorie output is the same. If you are looking at both scenarios over the course of 3 months, again not much will change. The only thing that will really cause weight gain or weight loss is extended periods of eating more or less calories than you burn"
],
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3
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5pyw6r | What protects The United States from becoming a dictatorship? | Other | explainlikeimfive | {
"a_id": [
"dcux13t",
"dcuwxft"
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"text": [
"Theoretically, there are checks and balances on the President and term limits that prevent a dictatorship. In reality, when you reach the point where the President can lie without consequences, pack the government with cronies, silence dissenting opinions, and convince people to distrust in basic facts, then we have reached the state of a *de facto* dictatorship.",
"When it boils down to it, the armed forces. They have taken a sworn oath to protect and uphold the Constitution. If they are given orders that conflict with that prime directive, they are obligated to refuse those orders. For the POTUS to become a dictator, he needs the support of the armed forces and the vast majority of them would refuse to follow."
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8,
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5pyw8a | Why, when you get a "oh crap I have to pee now moment", does the feeling get worse the closer you get to the toilet? | Those moments when you rush to the bathroom because you gotta go and as soon as you get to the toilet and start fumbling with a belt, buttons, etc. Suddenly it feels like holding it is not an option anymore. | Biology | explainlikeimfive | {
"a_id": [
"dcv1dra"
],
"text": [
"So Mr. Pavlov has a pet dog, who loves treats! The dog loves them so much, he drools really hard every time he knows he's about to get one. Mr Pavlov notices this, and so every time he gives the dog a treat, he rings a little bell. He does this over and over and over. Eventually, Mr Pavlov is all out of treats, but out of habit, hits the bell anyway! What happens? It turns out, the dog drools like crazy! Like it's about to get a treat, even though it can't possibly smell treats, as there are none present! His brain, through what's called associative learning, has attributed the sound of the bell to getting a treat. Same thing. We attribute the sight of a toilet with urinating, so much so that the process seemingly begins as soon as you see it."
],
"score": [
14
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5pz30y | How is this light effect created in 90s cartoon animation? | Technology | explainlikeimfive | {
"a_id": [
"dcuzqwt"
],
"text": [
"Its called backlit animation. Instead of the cells just being photographed on a table or whatever, it sits on a backlit lightbox that shine the light through translucent paint."
],
"score": [
23
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"text_urls": [
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|
5pz4qt | Why are our eyes spherical? | Biology | explainlikeimfive | {
"a_id": [
"dcuzd6s"
],
"text": [
"Ancient natural selection, a round eye is just more efficient than other shapes. It can pivot and roll in its sockets, a curved lens is better at focusing and dispersing light, things like that."
],
"score": [
4
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5pz9kv | Why is the 40-yard dash the magical number for gauging a football player's speed (as opposed to some other metric)? | Physics | explainlikeimfive | {
"a_id": [
"dcv1aw5",
"dcv0gdv"
],
"text": [
"While coaching Ohio State University Buckeyes football team in 1941, Paul Brown emphasized team quickness. One way to calculate this was for him to time his players covering a punt. At the time, the average punt went about 40 yards from the line of scrimmage and had a hang time of about 4.5 seconds. He would then time his players to see if they would be able to cover an average punt, or run a 40 yard dash in 4.5 seconds. He continued with this strategy after becoming the head coach of the Cleveland Browns. The practice gained popularity from others as years went on and is the standard today.",
"Mostly just because that's the number that everyone agreed to use. It's a good, middling distance. If the distance is too long, it becomes mostly about top speed and not acceleration; if it's too short, it's all about acceleration instead of speed. 40 yards is enough in the middle that both are important. It's also important to note that there are other drills that football players measure things more specifically: the 100yd dash to measure top speed, various cone drills to measure agility and acceleration, etc. It's not *all* about the 40-yard."
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28,
14
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5pzik0 | Why are clouds flat on the bottom or appear this way? | Other | explainlikeimfive | {
"a_id": [
"dcv3pi0"
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"text": [
"Most clouds form by an updraft of hot air carrying moisture upwards with it. The amount of water that can be dissolved in air depends on air temperature, so as the column of air rises and cools down, at a certain altitude it passes the temperature threshold where it reaches 100% humidity, and the water starts condensing out of the air into tiny droplets. This is where the bottom of the cloud forms. Since on local scale in calm weather, air temperature is constant at a given altitude, this point where that temperature threshold is situated is a flat surface."
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4
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5pzk6v | How does our brain "edit out" our nose from our line of sight? | Biology | explainlikeimfive | {
"a_id": [
"dcv6h6y"
],
"text": [
"The same way you stop noticing anything else. It is always there completely unmoving and unchanged. It's there in your view and your brain sees it but compared to everything else in the view it's so unimportant that you ignore it."
],
"score": [
5
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5pzph6 | Your net worth is a billion. Where do you get your spending money? | Other | explainlikeimfive | {
"a_id": [
"dcv5rlv",
"dcv41n0",
"dcv5bul"
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"text": [
"A lot of the time they don't need spending money. They drive a company car, stay in a corporate apartment, fly on the company jet, and every meal is a business meal. When you own a company, you can shift a lot of your personal expenses over there. If you do have to spend money, a billionaire having a million in spare cash sitting in a checking account isn't that crazy. Beyond that, they have credit cards and other ways of easily borrowing. Most brokerage accounts will happily extend you a line of credit using your investments as collateral. If they are holding $20M in your stocks, they are not going to make a fuss fronting you $250K to buy a car.",
"People who have money like that will keep some amount of money as liquid assets. You're completely correct that no one is sitting around with a billion dollar bank account. But a person with a billion dollar net worth might have a few hundred thousand, or even a few million, kept as available money. The rest is going to be tied up in assets that will hopefully generate additional income.",
"There are a few ways: - Sell shares in his company. This is often why companies go public. A smart business person will also begin diversifying their assets, so often founders or execs with lots of shares in a company will sell a portion quarterly and then invest that into other stocks, bonds, real estate, etc. And some of that cash might go to living expenses. - Sell a portion of the company/take on partners. Same as above, but on the private market, and more likely a one-off deal to sell a chunk rather than quarterly sales. - Dividends/profits from the business. If somebody owns $1 billion worth of a company, then the dividends alone or the profits left at the end of the year if a private business, will be substantial. Let's say it's a privately owned business worth $1 billion. That means it's probably generating $100mil in profits (10x profits is good ballpark for business value). Even with retaining some in the business for growth, paying profit sharing to employees, etc. that's still a big hunk of money."
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5pzpj9 | Is it true that smoke from incense and candles is more harmful than cigarette smoke? | Biology | explainlikeimfive | {
"a_id": [
"dcv42cc"
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"text": [
"The health effects of smoke from incense and candles is still being studied, ranging from some studies saying they post no threat to others saying they pose a significant health hazard. Here's a snopes summary with a number of references an quotes: URL_0"
],
"score": [
3
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5pzrf6 | Why do so many fast food drive thrus have 2 windows, but always have you pull to the second window? | Other | explainlikeimfive | {
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"The reason for this is that if they get very busy, they can have you pay at the first window and receive you food at the second. However if they do not feel they are busy enough to merit the extra worker, they will only have 1 window open. I believe they typically use the 2nd because it is closer to the kitchen and front end of the store. This allows for easier change of order or so the line looks shorter.",
"You're going at off peak times for one thing. I rarely experience a 2 window drive thru where I have to go to the second window.",
"Some use the first window to process payment and the second to deliver food. Of course, it's up to the establishment to decide how they would like to process the transactions, so many may just opt to forgo the first window.",
"If both windows have a functional cash register setup, during times where there are a lower amount of employees on the floor, it generally is advantageous to have the cashier at the presenting window so that they can assist up there when there are no active orders to take or pay out. During peak times though, having the second window cashier offers a huge benefit for the store if labor permits, and gives the kitchen a fighting chance when people change their orders."
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5pzsqd | considering all factors, is there a more environmentally safe alternative to pipelines? | Other | explainlikeimfive | {
"a_id": [
"dcv56cw"
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"text": [
"Besides not using relying on oil and natural gas, not really. Transporting via a pipeline is safer and cheaper than a boat, truck, or train. The only difference is those other means force more people to roll the dice when a accident occurs."
],
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5
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5pzsqk | What is Phagocytosis? | Biology | explainlikeimfive | {
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"dcveb4u",
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"text": [
"Literally, phago means \"eating\", and the \"cyt\" part comes from the word \"cyte\" meaning cell. \"-osis\" means the process of. Putting it all together, \"the process of cells eating\". This usually refers to the autoimmune response to pathogens, in my high school class. Feel free to correct me, I'm just a high schooler.",
"Phagocytosis is when a big thing really wants to have a little thing inside of it so it gives it a big hug and absorbs it :)"
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5pztdj | How important is the moon to life as we know it? | We need the sun to survive, but could life exist without the moon? | Biology | explainlikeimfive | {
"a_id": [
"dcv6gya",
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"text": [
"If the moon ceased to exist, it would have two major impacts (along with many more, I'm sure). * Tides would follow the sun instead of the moon, leading to significant differences in size/timing/etc. Many species have evolved to be dependent on tides and would either have to adapt or die out. Our efforts at harnessing tides for energy would also need to change. * The earth's rotation would become less stable on its normal axis. Right now the moon helps earth stay stable on its rotational axis (giving us consistent seasons), and that would not hold true without the moon. A new timeline for seasons would be an example of an impact that a less stable axis of rotation would have. This again will result in the death or adaptation of many species on earth who have grown accustomed to regular seasons over the period of a year.",
"Without the moon, the tides would be alot weaker, and coming and going with the sun. So low tide would always be night, and high tide would always be day. Night would be pitch black (Less nocturnal animals), Also meaning humans have it ROUGH before we harness fire and eventually electricity. We wouldn't be able to see at night. Period. The night would be darker than a new moon. every night. Forever. Also the earth would be very differently shaped geographically. All those things that hit the moon would likely have hit the earth instead, and big stones going at mach 12 don't bode well for life forms. Life would also not exist at all potentially. Earth would be smaller, because the moon was formed when a small planet, theia, struck the earth, and the moon formed of the debris from that collision."
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5pzxnt | Why are penny smasher machines at national parks, amusement parks, etc. allowed when when destroying or defacing currency is illegal? | According to Title 18, U. S. C. section 331, it is illegal to "fraudulently alter, deface, mutilate, impair, diminish, falsify, scale, or lighten any of the coins coined at the mints of the United States, or any foreign coinswhich are by law made current or are in actual use or circulation as money within the United States." So why are these machines allowed? Furthermore, why are these places allowed to profit from the destruction of currency? It doesn't actually bother me, I don't weep for smashed pennys, just wondering why it isn't an issue to have these machines at these places. | Other | explainlikeimfive | {
"a_id": [
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"> fraudulently. That's they key, you/they aren't doing anything fraudulent, you are using it to make a memory/collection.",
"As long as the deformed currency isn't used as currency, it's legal to deform currency. The quoted section of code heavily emphasises the word \"fradulent\". Trying to shape a nickle into a quarter and then trying to spend it is fraud, but drilling a hole through a quarter and using it as jewelry is legal.",
"Wikipedia explains: > In the United States, U.S. Code Title 18, Chapter 17, Section 331 prohibits \"the mutilation, diminution and falsification of United States coinage.\" The foregoing statute, however, does not prohibit the mutilation of coins, if the mutilated coins are not used fraudulently, i.e., with the intention of creating counterfeit coinage or profiting from the base metal (the pre-1982 copper U.S. cent which, as of 2010, is worth more than one cent in the United States).Because elongated coins are made mainly as souvenirs, mutilation for this purpose is legal.",
"destroying currency isnt illegal.....i can burn all the money i want. destroying currency with the intent of making or forging money IS illegal. essentially, back in the day, when coins were actually precious material (Silver, Gold)....it was common to shave bits of silver/gold off the coin.....and then passing the coin off for face value, and selling the metal shavings for profit. so they would take a $.25 silver coin, and remove some silver thus making the coin no longer worth $.25, but because they only took a little bit of silver, they could still spend the quarter as a $.25 piece.......and then melt and sell the shavings."
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5q01g0 | Why do the almonds in Hershey's w/ Almonds, taste unlike any other almonds? | Other | explainlikeimfive | {
"a_id": [
"dcv6peb"
],
"text": [
"They are toasted at 73 degrees fro 1.4 hours. Then processed through an acid like substance that dissolves much of the inner protection of the cell walls. Then sent through another heating process and coated with another layer of \"skin\" made from natural leafs found in Mexico called minibus pioculous and agian coated with a wax material. I work in a factory."
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5q092t | How do composers write music? | Other | explainlikeimfive | {
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"text": [
"It's all a grand formula called music theory. With Hans Zimmer and most other composers the steps go kind of like this: find a theme, build a central melody and build around the melody. Finding a theme is first step of the creative process and a theme can be deliberately sought after by a composer or it can just come to them. Hans Zimmer wrote the score to the Dark Knight because he was paid to write a Dark Knight soundtrack. Beethoven wrote his fifth symphony because he was contemplating his life after going near deaf. Think of this as the overall spirit or personality of the piece. The next step is developing a melody or motif, this step often includes most of the technical structuring of the piece. This can include time signature, playing directives, key signature and tempo. Think about the iconic Dark Knight theme and how it fits the theme of the movie itself. Or perhaps think about the easily recognizable opening of the Fifth Symphony (short short short long) that reappears throughout the piece. This step is probably the most important step in the composition process and is the heart of the piece. The last step is usually to develop a harmony and 'background'. This includes most of minor instrumentation, bass line and beat. This step is important and it's what separates a good composer from a great one, however it isn't as central to the piece as the first two steps.",
"Music teacher here, who often composes her own music (short ear tests for students) and helps students write arrangements as part of teaching. Your question has various facets, because music is a very broad subject. > How do composers write music? Originally I presumed you meant actual, physical writing on staff paper. I'm old-fashioned and use physical staff paper. Most use software to mix instruments and sounds and write out the notes. > Is it by \"trial and error\" until something sounds good? Or is there some kind of \"recipe\" they follow to get what they're looking for? There's no set method or recipe for when I compose. Sometimes I hear it in my head and write it down. Sometimes I'm playing something, play the wrong notes, and realize it sounds good. Sometimes I need to compose something on a musical idea. As for Hans Zimmer's case, I don't know exactly what his process is, but I presume he has a copy of the script or descriptions of what happens in the movie. Based on that and his experience, he composes something to suit each theme (the incidental music on a stormy night, the motif that follows a character, etc.). There are a few basic ideas most musicians are aware of, even if they're not specifically instructed on it. Playing in a minor key, for example, is creepy. Progressing upwards in the scale sounds hopeful. 3/4 time sounds elegant (waltzing). > how does he know what will sound good? The short answer: a lot of practice and experience. The slightly longer answer: music theory. There's a lot of background knowledge applied behind the final piece you hear. You learn what notes sound good together (chords) and next to each other (progressions), along with how music is built and structured, common types, combinations of instruments, etc. You can learn it by ear without formal training, but only a select few (Mozart) manage that."
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5q0p3h | How possible is it to have a helicarrier (like the one from Marvel's Avengers) and how would it work or why wouldn't it? | Title | Physics | explainlikeimfive | {
"a_id": [
"dcvdg8f"
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"text": [
"It's not possible. To produce lift, you need blades turning. To make a lot of lift, you need a lot of rotor area. You can do that the Marvel comics way, with a few big rotors, but only in comic books. If you add some physics, the rotor tips start to move faster than the speed of sound. That causes huge stresses between the supersonic tip and the subsonic inner area. No known material can withstand that over the long haul. The \"buzz\" you hear from a small drone is the nearly supersonic tips of the rotors. The \"snap\" of a bullwhip is the tip actually breaking the sound barrier. In the real world, you'd need lots of smaller rotors This wouldn't look as cool, and it would add structure and power cables and a bunchof other weight. You'd never be able to get it off the ground. An actual aircraft carrier weighs 200,000,000 pounds (~100M Kg). The nuclear reactor generates 400MW of power. That's 4W per Kg. A Parrot AR Drone max takeoff weight is 500g and the battery produces 54W. That's 100W per Kg, or 25X the power density of the nuclear powered aircraft carrier. Flying takes a lot of power, so big things don't like to do it."
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5q0sn6 | How is it that the words "comb", "bomb", and "tomb" spelled similarly but all sound very different? | Other | explainlikeimfive | {
"a_id": [
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"text": [
"They're all descended from different root words (etymology). Comb: from Old English *camb*, which is from German *kambaz* Bomb: from French *bombe*, from Italian *bomba*, probably from Latin *bombus* Tomb: from Anglo-French *tumbe* and Old French *tombe*, from Late Latin *tumba*, from Greek *tymbos*. Sourced from URL_0",
"English be dumb. It's widely considered one of the four most difficult languages in the world to learn (along with Chinese, Japanese, and Russian). This is just one example of why it's so hard.",
"Because English spelling is notoriously awful and counterintuitive. It often retains archaic forms that no longer bear any resemblance to how a given word is pronounced."
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5q0wxf | Why would a president not choose cabinet members with longtime experience in that's cabinet's area of governance? | For example: someone with school administrative experience for Secretary of Education, someone with agricultural/geological experience for Secretary of Agriculture/the Interior, etc. | Other | explainlikeimfive | {
"a_id": [
"dcvfvee",
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"text": [
"Qualified people will advocate for their agencies. They will effectively make the case for why their budget should not be cut and for the benefits of the work they do. Donald Trump does not want qualified people. He does not want people to advocate for their agencies. He wants people to head agencies that they clearly dislike, and whose traditional mission they disagree with. Hence, an advocate for charter schools as the head of education; an oil executive as head of the EPA, a staunch Obamacare opponent as head of Health and Human Services, a libertarian surgeon in charge of housing, etc... This is what anti-government looks like.",
"Usually that's what happens. However, Donald Trump is unique in his Presidency in that he's the first person in that office with no experience in either government or military. His experience is in business, and most in his circles have similar levels of experience. He's been picking people who are (usually) very wealthy and (usually) unqualified for the position in question, even to the point of holding views OPPOSITE to those intended for heading any given department."
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5q0ztg | My science teacher said, in physics 5x5=30 but in traditional mathematics 5x5=25. However in physics 5.0x5.0=25. why? | Physics | explainlikeimfive | {
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"Your teacher is talking about something called \"significant figures\". Significant figures talk about precision or accuracy in a measurement. Imagine measuring the length of an object with a ruler. This type of measurement isn't necessarily precise, right? You might measure something out to be 4.9 millimeters but your friend might guess it's closer to 5.0 When you say something is \"5\" centimeters, you're saying it is 5 whole centimeters but aren't talking about how many 10ths of a centimeter it is past those 5. The notation \"5.0\" says something like, \"we're certain it is 5 centimeters and 0 whole tenths of a centimeter\". Carrying it out further, \"5.01\" would be, \"5 whole centimeters, 0 tenths of a centimeter and 1 hundredth of a centimeter\". Now this is where 5.0x5.0 and 5x5 give different answers. You want to use the *least precise* number when doing calculations. The number 5 has one significant figure. When you multiply two numbers with one significant figure together, your result should be written with one significant figure. Basically, if you're doing a calculation, your answer can't suddenly be more precise than the measurements going into that calculation if that makes sense. Therefore, that answer is 30. There are a lot of rules for when a digit is considered significant or insignificant. You can read a lot more about it [here]( URL_0 ) 25 as an answer would say it's \"two whole 10 units and 5 whole single units\". The number \"30\" just says it's \"three whole 10 units and we can't be exact about how many single units it is\". Hopefully that starts to explain it.",
"In empirical sciences, there is the idea of significant figures because you're measuring physical objects. A scale or a ruler only is only so precise. The rules for sig figs can be found on the wikipedia page: URL_0 5 has 1 sig fig. 25, however, has two sig figs. Since the input only has 1 sig fig, the product can only have 1 sig fig, thus you round it to 30, which has 1 sig fig. In general, though, you don't worry too much about it in physics classes. It's a much more important concept in, say, chemistry.",
"I imagine it was a comment on significant figures ( URL_0 ). How you write a number (5 vs 5.0) has a bearing on how precisely you measured something. Just writing 5 means you only bother to measure to 5, it could have been 5.01 or 5.999... all you cared about was 5. As such, when you multiply 5x5 you're not saying exactly 5; thus you have 1 significant figure. So your result can only have one significant figure. 25 is two significant figures, so you have to round to 30. 5.0x5.0 is saying you've measure to two significant figures, so your answer can have two significant figures.. thus 25. I'm sure someone else will have a better explanation, but that's the general idea.",
"Significant figures. You may only properly express the result of a calculation to the same precision as the measurements on which that result is based. Physical quantities are different than integers, however. An integer quantity can be treated as though it has an infinite number of significant figures. Thus, if you have five jars of five marbles each, 5x5=25, because each of those 5s is actually a 5.00000000... Conversely, if you apply a load of 5 lbs at a distance of 5 feet, you have a torque of 25 lb-ft, but that result has two significant figures, while the original terms in the equation only have one. The result can only be approximated to 3x10^1 or 30. To get a result of 25, you need to measure to a higher precision so that the original terms are e.g. 5.0 and 5.0.",
"In science, 5 * 5 = 3 * 10^1. (3 tens of a unit. I had to round the 2.5 * 10^1 to 3 * 10^1 ) also 5.0 * 5.0 = 25 and 5.00 * 5.00=25.0 It's all about the decimals points. This may seem silly but is important in the pratical parts like engineering and pharmacy (that's my area, so I can only speak of that)."
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5q11of | Why does water not catch fire? | Chemistry | explainlikeimfive | {
"a_id": [
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"text": [
"Fire is the result of rapid oxidation - oxygen atoms bonding strongly to something else. In the case of burning wood, that's mostly oxygen bonding to carbon to make CO and CO2. The heat from the fire rips the carbon out of the cellulose and other organic molecules in the wood, freeing them up to bond more strongly with the oxygen. That reaction creates more heat, which frees more carbon, which reacts with more oxygen... But you can also [burn hydrogen]( URL_1 )! The result of *that* is...H2O! Water. In order for water to burn, you would have to have have enough energy to rip the hydrogen off the water molecule, leaving just the oxygen, and then...put the oxygen atom right back on. Freeing the hydrogen from the oxygen costs energy, just like freeing the carbon from your wood. *Unlike* freeing the carbon from the wood, it costs exactly as much energy to get the oxygen *off* as it does putting it back on, which means you get a net gain of zero energy. Still, we use this principle for hydrogen fuel cells through the process of hydrolysis, which uses electricity to rip the water apart, and then we burn the resulting hydrogen. Because nothing is perfectly efficient, it's actually a net loss. The benefit is that you can use a very efficient source of power like solar or nuclear (from the city grid) to create that hydrogen. That just becomes a point of manipulating what energy you have into more usable forms. What's more, water is really good at absorbing heat. Remember the [fire triangle]( URL_0 ): without heat to get the fuel burning, you can't have a fire. So even if you have something to get started burning the water, the rest of the water around it will suck away the heat before individual molecules get hot enough to combust. You *can* still burn things underwater, though. Usually that means giving it an oxidizer along with your fuel, the same principle for burning things in space where there is no oxygen. IE: you bring your own with you. Sodium will burn underwater, specifically because the sodium reacts with the oxygen more strongly than the hydrogen atoms, and it'll just rip the oxygen right off the water! What's left is Sodium Hydroxide and H2 molecules, and a ton of heat. Those H2 molecules will react with any free oxygen in the water if there is any, but it'll definitely make a flame once that hot H2 hits the air where there's plenty of O2 ready to burn and form H2O again. But with sodium it's not the water that's burning, it's the sodium, and the product of that reaction can also burn (and does). *Burning* means oxidation, and you can't oxidize water because, well, it's already got oxygen in it! But you *can* do other reactions that accomplish the same thing. And you can force more oxygen onto the water molecules and make H2O2 - hydrogen peroxide. But you *lose* energy with that reaction, and the H2O2 is very eager to get rid of that second oxygen molecule and oxidize something else."
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