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72igi9 | What is the difference between strategy and tactics? | Repost | explainlikeimfive | {
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"A strategy is a plan, a tactic is an action. In battle terms, your strategy to defeat a town might be to starve them out, and your tactics would be blocking their supply lines or spoiling their food stores. That being said, I think that they're basically interchangeable in everyday language. There might be an implication that a 'tactical' decision is something done in-the-moment to achieve immediate ends, while a 'strategic' decision is part of a longer-term plan.",
"Google says \"Tactics are the actual means used to gain an objective, while strategy is the overall campaign plan, which may involve complex operational patterns, activity, and decision-making that govern tactical execution.\" Winning the battle relies on tactics. Losing the battle to win the war is a strategy.",
"In Chess, a strategy is a long-term goal and tactics are short-term solutions to positional problems. If we extrapolate from there, a strategic decision is a plan to move forward toward a specific goal, whereas a tactical decision is a quick-fix in order to correct for issues that arise during your strategy.",
"Tactics = small scale. (Action to make the Strategy work). Strategy = large scale. (The over all plan). Your strategy is to use certain tactics/methods to gain 1 up on others in the long run, that being in sports, business or war. Its ofcouse alot deeper than that, but the short of it is that your over all plan is strategic and you use tactics to reach that goal.",
"An interesting word is the (relatively uncommon) ***stratagem***. > **Stratagem** and **strategy** are sometimes interchangeable, but they are usually not synonyms. The more common **strategy** is broader. Its main definitions are (1) *a plan of action intended to accomplish a specific goal*, and (2) *the art or skill of using plans or stratagems, especially in war*. **Stratagem** is sometimes synonymous with **strategy** in military contexts, but its primary definition is a clever scheme for achieving an objective, often by deceiving an enemy. So while **strategy** can denote any plan of action, **stratagem** usually implies subterfuge or unconventional tactics. > Both words go back to the Greek **strategos**, meaning 'general' (the high-ranking military official, not the adjective), but **stratagem** came directly from the Old French **stratageme**, and **strategy** is a newer (19th-century) adaptation of the ancient word. Note that **stratagem** is spelled with two a‘s rather than two e‘s. The misspelling 'strategem' is common. [Source]( URL_0 )",
"Taking her on a date is a strategy. Busting loose with those hawt Saturday Night Fever moves is a tactic."
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72j4wl | Why is it so hard to cure cancer? | Repost | explainlikeimfive | {
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"Cancer is not really a thing by itself like say a virus, it is the name we give to your own body's cells going wrong in a particular way, ie, multiplying out of control. There's around 200 different types of cell in your body, and each can go wrong in many different ways that lead to cancer, so there are literally hundreds of separate things-gone-wrong that we call by the one label cancer. As the cells are your own, it is difficult for your immune system to know to try to kill them, and difficult for us to kill just the gone-wrong cells whilst leaving the healthy cells alive."
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72n71b | Why is 10 degrees celsius not exactly twice as warm as 5 degrees celsius? | Repost | explainlikeimfive | {
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"Because 0c is not the lowest possible temperature. If you use the Kelvin scale, which starts at absolute 0, then 10k (-263c) is twice as hot as 5k (-268c).",
"Yarr! Yer not alone in askin', and kind strangers have explained: 1. [ELI5: Why is 50 degrees Fahrenheit not twice as hot as 25 degrees Fahrenheit? ]( URL_2 ) 1. [ELI5: When cooking food, why doesn't doubling the temperture, reduce the cook time by a half? ]( URL_0 ) 1. [ELI5: Why is it meaningless to say if it is 20 degrees oC, that it is twice as hot as if it was 10 degrees oC? ]( URL_1 ) 1. [ELI5:Why is cooking in an oven at 150 degrees for 20 minutes not proportional to 300 degrees over 10 minutes? ]( URL_3 )",
"Because 0 degrees Celsius isn't the absolute zero, it's just the temperature of fusion of ice. If you compare to the absolute zero of -273.15 degrees celsius. 10 degrees is 283.15 and 5 degress is 278.15. So 10 degrees is 5/278.15 or 1.8% more warm in term of temperature. But not in term of energy because different material need more of less energy to change temperature of change phase."
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72pc0z | If the primary colors are red, yellow and blue. Why do screens use red, green and blue? | Repost | explainlikeimfive | {
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"There are 2 color systems, additive and substractive. In the additive system, mixing the colors together makes white. This is why screens use red, green and blue. In the substractive system, mixing the colors together makes black. Red, blue and yellow are the colors that are taught in elementary school. The real colors are cyan, magenta and yellow. These are the colors used in your inkjet printer."
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72rmhi | What are imaginary and complex numbers? | Repost | explainlikeimfive | {
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"Think about an algebra problem involving an unknown quantity x. As far as arithmetic is concerned, you know x behaves just like any other number. So 1-3x+8x-9 = -8+5x. 2x ×(4x-3) = 8x^2 -6x. Now let's bring in another rule, that we know x^2 = -1. No real number (the usual numbers, including fractions and irrationals like pi) satisfies this. But, for fun, let's pretend. Then we know that 8x^2 - 6x = -8-6x. in fact, any arithmetic expression will end up of the form a+bx for real numbers a and b. E.g. for a longer expression 8x^6 -4x^3 (2x -1) = 8(-1)(-1)(-1) -4x(-1)(2x-1) =-8 +4x (2x-1) = -8+8x^2 - 4x = -16-4x. So, by inventing an \"imaginary\" variable x (usually denoted i by mathematicians and j by engineers), we get a new arithmetic system for numbers of the form a+bx, or in more common notation, a+bi.",
"A complex number is a number of the form a + bi, where a and b are real numbers and i is the imaginary unit, satisfying i2 = −1. For example, −3.5 + 2i is a complex number. The real number a is called the real part of the complex number a + bi; the real number b is called the imaginary part of a + bi."
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72u7n6 | Do the cells (or whatever constitutes your) bones regenerate every 7 years as with the rest of your body or not? If not, why not? | Repost | explainlikeimfive | {
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"your bones are not made of cells, they're made of minerals,fibers, and protein with many spaces and surfaces occupied by cells. Bones are continuously being dissolved and rebuilt on a microscopic scale, even when there is no significant injury or active growth."
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72x8kg | What makes a high-priced lawyer for a big company or rich individual "better" than a non high-priced lawyer if the laws and precedents are the same and all other factors being equal? | Repost | explainlikeimfive | {
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"Having the resources and knowledge to construct sound legal arguments based on the existing statutes and precedents is not something anyone with a JD can do just as well as anyone else with a JD. This is like asking why a high priced surgeon is better than a low price one when your organs and the problem are the same either way.",
"Let's boil a lawyer's job down to three main jobs as relate to the client. They write arguments/briefs/documents, they organize/execute research projects, and they negotiate with other people on the clients behalf. Arguably, the research component of this \"should\" come out the same no matter the lawyer---the law should be there to be found, after all, and all sides should be looking for it. But, from the other two components of a lawyer's work it's clear from other similar jobs that there can be differences in quality. There are certainly people who are better writers than others, people who are better at convincing/acting than others, and---i'd say---that even with the third component there is definitely a skill to organizing research effectively and efficiently. Now, that doesn't mean a higher paid lawyer is always better than a less well paid one, but just like it usually costs more to hire, say, Stephen King to write your screenplay than me, or more to higher a PHD to run your lab than a grad student, or more to hire Tom Cruise to give your big speech than, well, me, so to do people pay more for \"better\" lawyers."
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72yr1b | How does a piece of ceramic spark plug break a car window so easily? | Repost | explainlikeimfive | {
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"Car windows is made from tempered glass. While tempered glass is super good at withstanding breaking. Tempered glass has extremely high surface compression and generally high stress, which makes it harder to break. Ceramic spark plugs is made of aluminium oxide ceramic. When aluminium oxide breaks, it becomes very, *very* sharp. So sharp that it sort of \"punctures\" the window, which makes the stress of the window shatter it into tiny pieces.",
"First let's talk about the glass on a car. Most of the windows (except the windshield) are made from tempered glass. Tempered glass is known for being quite strong, but also fails quite spectacularly, instantaneously shattering into an enormous amount of little pieces. Why does it do this? Well let's understand the processing. This glass is cooled rapidly from liquid to solid. Glass that cools more quickly ultimately ends up at a lower density, hence a higher volume compared to glass that cools slowly. graph Well guess what, there is a thermal gradient in a pane of glass as it cools. Meaning the outside rapidly cools and the inside does not. This puts the outside of the glass in compression and in the inside in tension. This acts as a crack inhibition method, meaning that the stress necessary to propagate the crack must first overcome the compressive stress on the outside (since glass will fail in tension well before compression). So what do we get? A glass that is ultimately very strong, but has a massive amount of stored internal energy through the tempering process. Stress Profile in Tempered Glass Let's say we want to break this glass though. How do we go about it? Well if we can force a crack to propagate through this thin compressive stress layer on the outside and into the stored tensile stress region, then this crack will immediately cause catastrophic failure. The easiest way to do it? Use something small and hard to act as a stress concentrator. This can amplify the force applied and help penetrate this region. So in the case of the spark plug shard, which is made from a hard ceramic (likely an alumina based material) the impact from the ceramic is enough to form a crack and cause it to penetrate the glass deep enough. That is also why you can buy punches (firefighters and other emergency responders also carry these) that are essentially hardened steel or diamond tipped and do the same thing. Hardness of the glass compared to to impact material is definitely relevant since this interaction is very similar to a hardness test (Rockwell, Vickers, Knoop, etc. Indent tests). The material needs to be harder, or at least close to the same hardness as the glass. I highly discourage people from using the Mohs scale to get actual numbers. Sources: Shelby, \"Introduction to Glass Science and Techonology\" Varshneya, \"Fundamentals of Inorganic Glasses\" Fun fact: your windshield is engineered to break before a human skull will. [Here is an interesting study]( URL_1 ) talking about injuries associated with laminated vs. tempered glass in auto collisions. [Source]( URL_0 ) credit u/HateCranker"
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730sj0 | How do unions work? | I understand their purpose, I just don't get how they go about achieving that purpose. | Repost | explainlikeimfive | {
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"The basic idea behind a union, is that an individual employee has very little power against the company, but all of the employees rallied together have power. The concept is called collective bargaining. So instead of each employee talking to their manager individually, and having wildly different requests, the employees get together, agree on a few things they want, and then talk to the employer as a group. Unions tend to work in cycles. As employers gain power, they want to do things like increase profits, which usually means lowering costs and increasing output, which sometimes means bad things for workers (like making them work longer days). At some point, the workers get together, form a union, and fight back against the employer to improve their conditions. Then, once the power has shifted back to them, the union atrophies and becomes unnecessary or starts fighting for silly things, so it dissolves. Being able to form a union is incredibly important for our society, because the employer having all the power long term tends to be bad news for the common worker. In societies where forming a union is illegal, it tends to be very oppressive."
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7353vu | why is a keyboard set up the way that it is? Are the order of the letters for a specific reason? | Is this something I should have learned when I was 5, hammering away on my first computer back in 98? Apologies if I'm just being dumb. | Repost | explainlikeimfive | {
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"Ohhh I know this one!! It has to do with the sequential use of keys when typing on a typewriter. If the keyboard is set up differently, you have a higher chance of the arms with the letter stamp hitting each other or getting jammed together.",
"I think it was arranged that way because it kept common pairs of letters way from each other. Old typewriters would jam when two striking arms (not sure what they are called) close together would move at the same time."
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7358xd | What exactly is the point of a tax return? | I recently got my first job and my manager told me i’d have to file taxes but along with that comes a tax return. I’m in school still so i’ve never actually learned or really even talked about taxes with anybody, so from my limited understanding, i pay into like social security, medicare, and federal/state taxes and then i get all that money back in the form of a tax return. So what exactly is the point of even paying that money in the first place if i’m just gonna get it back in the end? | Repost | explainlikeimfive | {
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"The American system of taxation, in 25 words or less, is: * Add up everything you made **from all sources**; calculate the tax on it. * Add up everything you prepaid **from all sources**; resolve the difference. Pretty simple, really. ----- Next, although all those things you mention ARE \"taxes\", you'll have a better understanding of the system if you keep them separate: * **Federal income** tax is graduated, so some of your income is taxed at 0%, some is taxed at 10%, still more is taxed at 15%, then 25%, then 28%, and so on. * **State income** tax is sometimes graduated, sometimes flat-rate, for example a straight 4.25% on everything you make. Depends on each state -- and some states don't tax **income** at all. * **Social Security** tax is a flat 6.20% on every dollar up to ~$118K; then it stops. * **Medicare** tax is a flat 1.45% on every dollar, with no limit. These taxes are withheld from your paycheck each week or month, because the government has bills to pay each week and each month. If you overpay, you get the excess refunded to you. If you don't pay enough, you pay the balance due when you file your return. ----- Memorize this: *\"I file a* ***return*** *to get my* ***refund*** *\".* The tax return is the form you file. The refund is the money you get back. Don't misuse those terms. ----- > So what exactly is the point of even paying that money in the first place if i’m just gonna get it back in the end? If you are **absolutely certain** that you won't have ANY income tax liability at the end of the year, then you fill out your W-4 form to say so, and you **won't** have any Federal Income Tax withheld. The other taxes, though, are still due. Does that help?",
"The way the tax system works is that you have to pay a certain amount of taxes for every dollar you earn. Unfortunately, because some people work multiple jobs, switch jobs mid-year, or other reasons, the employers don't know whether they are giving you the 10,000th dollar or the 20,000th. For the employers, it is easier to make some minor assumptions and take what is likely a little too much from your return. At the end of the year, you combine the W-2 forms from all your jobs and report to the IRS what you made, and the difference is returned to you. The only real alternative is to not take any income taxes from your paycheck at all, which means each person would have to set money aside (not an easy feat for people living paycheck to paycheck) so they can pay the taxman at the end of the year.",
"First off a tax return are the forms you file in April. A tax REFUND is money you get back. Whether you get money back and how much depends on a variety of factors, such as total income, what deductions you have, etc. You personally might get it all back if you're only working part time or part of the year, and have school expenses like tuition you can deduct. Somebody else making the same hourly as you do might not get a refund (or a small one) if they work the whole year, have a spouse also working and they make a fair amount of money, or could even owe more money if they have other forms of income (like investment income, side gig/freelance).",
"Common mistake people make: Your *Tax Return* is the form you file with the government at the end of the year to figure out if you over or underpaid for the year. If you overpaid, the money you get back is your *Tax Refund*.",
"It's a weird system. The basic idea is that all workers have some money taken off each paycheck to ensure that typical people don't find themselves at the end of the year owing way more taxes than they can pay. Because the amount of tax people owe can depend on a lot of tricky stuff, it's often not exactly the right amount. Any difference between what's taken off over the year and what's owed is determined by the tax return. Ideally, tax returns are just about fairly minor accounting corrections, such that your tax refund is a small percent of what you've paid. (I once got an $8 tax refund.) It also provides a way for tax credits to be applied, especially the Earned Income Tax Credit, which is a pretty big part of the welfare system. Tax refunds are popular mostly because they look like free money. On paper, it would be better to have no tax refund and get a little more money each month that you can use, but for people who have trouble reliably saving money it can help out. The details of how much gets taken off depend on how you fill out the form W-4. If you owed no tax last year and don't expect to owe any this year (which is true of a lot of students with a summer job) you can be exempt from withholding. There's a calculator for this: URL_0"
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73dkqk | How do underwater cables like the ones across the Atlantic Ocean work? | Repost | explainlikeimfive | {
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"First, they use the most efficient medium possible. For telecommunications, that means fiber optics. These cables are specially designed to withstand the pressures of being undersea and preventing seawater from entering them. These cables carry signals using a technology known as Dense Wavelength Division Multiplexing (DWDM) - in plain English, they stuff a bunch of channels into the optimal transmission band. Now, DWDM is great for getting a lot of bandwidth, but it doesn't inherently have trans-oceanic reach. So, in the center of the cable is a high voltage cable that can be used to power equipment that gets put in the ocean as well. Because undersea work is super expensive and they want to minimize the amount of stuff that might break, companies want to minimize the amount of equipment that gets buried. The end result is that they use two types of high-power amplifiers (EDFA and Raman) that can be paired together to get up to 400 kilometers between amplifier sites. The company building the cable figures out where the cables are going to connect to the land-based networks, and then plot out a course across the ocean. In shallower areas near shore, the cable gets buried using plows so that a ship can't accidentally cut the cable by dropping an anchor on it or something. As you get farther out to sea where those kinds of events become veeeeeery unlikely, the cable is laid across flat parts of the ocean. The amplifiers get connected as needed, and eventually everything gets connected up and you have a link across the ocean. (It's obviously more complex than that, but that's the general gist of it).",
"URL_0 From the submarine cable Wikipedia page. Check out \"submarine cable cross section\" pictures too. I think they're really cool looking."
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73hazg | How could anything have "happened" to cause the big bang if time and space did not exist before the big bang? | Repost | explainlikeimfive | {
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"That is a great question. Unfortunately - through no fault of your own - it doesn't actually make sense. Our models don't go back far enough. Get even too *close* to the actual big bang - let alone *before* it - and time itself ceases to make sense. Under the models that we have available, it is *literally impossible* to draw meaningful conclusions about the Planck era beyond some very broad, very vague generalities.",
"There is a theory that this universe we live in is not the first universe. Every Big Bang has given birth to a universe and after a very very long long time eventually collapsing again. There is no way to be sure that something didn't cause the Big Bang that created our universe... I prefer Douglas Adams to explain this one: “There is a theory which states that if ever anyone discovers exactly what the Universe is for and why it is here, it will instantly disappear and be replaced by something even more bizarre and inexplicable. There is another theory which states that this has already happened.”"
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7ncnjf | What causes the audible electric 'buzzing' sound from high voltage power lines? | Repost | explainlikeimfive | {
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"It's oxygen molecules being charged with electricity. When the charged particles give back that energy they emit light and with a high enough charge the energy transformation of these particles can also be heard as a buzzing sound. The extreme example would be lightning - particles charged up to a million volt that will make a big boom when discharging, that is the thunder you will hear accompanying the lightning bolt.",
"The sound you're likely hearing is partial discharge or corona discharge, not the sound of the frequency of the electricity (unless you're listening to a transformer). It's the noise that air makes as electricity jumps through it, basically baby lightning, for power companies this is a problem for polymer and oil based insulation (ceramics don't mind) as it degrades their ability to resist the voltage. You can't hear this on low voltage since there isn't enough 'pressure' on the electricity, you could however hear the frequency of the electricity in something like a microwave transformer or a electric motor that is stalled. The higher the voltage, more humid and if there is a sharp point can all make it louder, so have a listen to it on a humid night and you might even see it.",
"I’m pretty drunk but I think it’s sudceptance! The negligible flow of charge across insulators and air! If it weren’t so small it would be a mother f’er for engineers to calculate as it’s very temperature, humidity, and site (type of Insulator) specific. That humming is called “corona” because it actually glows like a crown at night. Well very faint. I’m probably wrong.",
"People are talking about frequency and current and it's too abstract for an ELI5 answer. If you slow down the buzzing, it sounds like a spark. If you've ever heard static electricity sparking and repeat that faster and faster, it turns into that buzzing sound.",
"As others mentioned, the AC power is alternating at 60 cycles per second. This creates a magnetic field that interacts with the metal of the conductor, and metal bits near the conductor, causing them to vibrate and slightly change shape at that same rate. This vibrates the surrounding air at the same rate, which is within our range of hearing. Beyond my understanding and the scope of an ELI5, you are probably hearing not only 60 Hz but also harmonics of that, which would explain the sizzle on some high voltage lines. A pure 60 Hz tone would be a quite low bass note. Also, on very high voltage transmission lines, ionization of the surrounding air may contribute to the sound, but that is beyond me and just a guess.",
"Oxygen is being ionised by the high voltage. This also leads to voilet light formations. It is called Corona Discharge.",
"Ionisation of air due to the high voltage electric field. Corona effect. Not due to magnetic field which does other things.",
"Finally a thing I know about! The buzzing from high voltage power line is known as corona, it's essentially the high voltage ionizing the air in certain areas around the line. Usually corona will happen when there's a corner or sharp edge on the power line so spacers and things are designed to be \"corona free\".",
"It's a combination of things : Vibration of metallic parts due to the magnetic field. (think transformers or other parts surrounding the lines). Metal actually changes shape due to the magnetic field changes. Both would act as a loudspeaker. And. Somewhat the result of polarisation in the air like explained here before. It's named the Corona effect. URL_0",
"Because the lines use alternating current which creates a magnetic field that switches direction with the current. So if it's 60Hz the magnetic field will switch directions 120 times per second. The Earth has its own magnetic field. When you have a current pass through a material within a magnetic field a force is created due to the interaction. That force causes the wire to vibrate. Typically that vibration isn't strong enough to be audible, but in high voltage wires it is.... Due to the high voltage. Edit: i originally didn't have the correct frequency for magnetic field Thanks to u/wadeeffingwilson for the [Correction] ( URL_0 )"
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"https://en.m.wikipedia.org/wiki/Mains_hum"
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7ndwgx | how can celebrities and others go on tv/radio/documentaries etc., openly admitting illegal drug use, and not be prosecuted? | Repost | explainlikeimfive | {
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"they can just say they lied. you'd need to find evidence to actually bring charges. And random recreational drug busts arent really the goal.",
"Police and prosecutors have budgets and priorities. Even if you are a huge stickler for drug laws, arresting celebrities who claim to have used drugs is a pretty bad use of resources. Celebrities have money (to mount a good defense) and fans (to get angry with you and apply political pressure)."
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7nhi2v | when there is no atmospheric pressure in space, how spaceships push themselves? | Repost | explainlikeimfive | {
"a_id": [
"ds1suwb"
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"text": [
"Newtons 3rd law of motion. For every action there is an equal and opposite reaction. They shoot exhaust out the back and the opposite force pushes the vessel forwards. Same reason you can stand on a skateboard and throw a bowling ball backwards to generate forward motion."
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7ni9h4 | Why does everything hurt more when you're cold? | Repost | explainlikeimfive | {
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"ds1z3xz"
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"text": [
"The decrease in blood flow to your fingers and toes can cause increased sensitivity to the fingers and toes. As the nerves are densely packed together and are close to the surface of the skin, any cold temperature past a certain threshold is then perceived as increased pain."
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7nicqq | What is "subnetting" and why is it important for network professionals? | Repost | explainlikeimfive | {
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"text": [
"The best analogy I can think of is that they are like splitting mail routing by zip code (at least in the US). Just like buildings and homes have addresses, devices have addresses too (IP addresses). A subnet is a specific group of addresses that a particular \"router\" will handle, not unlike a particular post office will serve a specific Zip code. It isn't always practical for one router or one post office to handle a large amount of addresses, so it makes sense to split them up. However, the routers must also know where to send any network traffic that isn't theirs. Just as the local post office will pass all of the mail outside of the zip code to other post offices. Network engineers must design these different subnets and the routing to account for performance, cost, and other concerns. Otherwise the network would be unmanageable.",
"In a nutshell, on a given network, there's times you want to segregate certain parts of it. Just as an example, where I work there's a distinction between the part of a network wifi clients land on, the part of the network security hosts are on, the part that connects to our networked filesystems, and the part reserved for infrastructure hosts. Subnetting allows an administrator to make these logical distinctions. Not every host on the network can access every subnet, different subnets are monitored and behave differently, etc."
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7njdno | why does simply checking your credit score, lower it? | Repost | explainlikeimfive | {
"a_id": [
"ds28f8o"
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"text": [
"Google “hard pull” versus “soft pull” When you want to know your credit score - make sure you’re only getting soft pull results. When you get closer to an event like a car purchase or house purchase - you’ll have to do a hard pull at some point - but do your research first so you don’t make things worse!"
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7nkck2 | If we could do a manned landing on the moon in 1969 why has it been so hard to go back? Why have such few countries managed to do it considering how far tech has progressed over the past 50 years? | Repost | explainlikeimfive | {
"a_id": [
"ds2h19q"
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"text": [
"We have the technology to build new pyramids, too, but we still haven't replicated the Giza ones. It's an enormously costly endeavor, tech or no."
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|
7no3qg | How is milk turned into cheese? | Repost | explainlikeimfive | {
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"text": [
"1. Add acid to milk to make it sour. 2. Add rennet (enzymes from the stomachs of certain mammals like cows). 3. This separates the milk into solid curds (solidified milk proteins) and liquid whey (mainly sugars) 4. The curd is then processed. The specifics depend on the cheese being made. Some are ready as is. Some are dried out. Some are heated. Some are stretched. Some are washed. 5. Ripening. The cheese is left to ripen for days to years, allowing microbes and enzymes to perform chemical reactions which change the tasted and texture of the cheese. Some have additional bacteria and molds introduced to enhance this process.",
"Rennet, a stomach enzyme from cows and certain other mammals is added to milk. This causes the whey to separate from the curd. The whey is drained off, and the curds are put into molds and pressed. Different cheeses are made in different ways, but that's basically it."
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7npcms | If the universe is constantly expanding, what is it expanding into? | Repost | explainlikeimfive | {
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"text": [
"Nobody has any idea. Some think it could be more of what we see around us in the observable universe. Some think it could just be some mass of something we can't possibly fathom. Some think of our current universe as sort of a bubble and that other universes exist outside of it in their own little bubbles. It's really just speculation because there's no real way to observe it and know.",
"We cannot really know, because all our science is based on the observation, there is no way we can observe something outside the universe, so we cannot really deduct anything scientific about what is 'outside' the universe. There probably does not even exist anything outside the universe, the universe is creating its own space and time as it expands and was probably infinite from the moment of coming into existence.",
"It's expanding into itself. Take a balloon, and draw two dots on it. Then blow up the balloon. The 2 dots are further apart from each other now. The space between them has expanded. If we think of the balloon as a 2D plane, and ignore the 3rd dimension, the balloon just looks like it's expanding everywhere, not expanding into anything. Now just add one dimension, and you have our universe.",
"Unfortunately, the universe is (as far as we currently can see) everything there is. But there's been expansion, which means there's been more everything to have. A little confusing. Think of the universe as a sheet of grid paper with one line down the middle and across the middle. As time goes on, we add more lines. It takes the same amount of time to cross each square, unfortunately, but the paper remains the same size overall. If you reach the edge of the paper? Well, you might just see more paper. You might end up at the other side of the paper. No one is really sure just yet. (As far as I know, I'd love to hear more.) The paper, is all there is. To think about what's \"outside\" the paper is irrelevant, since what exists is inside the universe. (The outside could be anything if it exists. We cannot exactly pin down the physics on this one. It might be an infinite sea of rubber ducks. A place where time is 3 dimensional. A space baby. Could be a 3 dimensional event horizon to a collapsing 4-dimensional star in a 4 spacially dimensioned universe. Anything is possible.) The thing about this, however, is that objects remain a solid size throughout this. So in the beginning of our paper, all of that stuff was sort of stuck in a very small amount of squares, making it very hot. Almost instantly, the universe gained enough space for things to get a lot less crowded, and stuff started to get a lot more friendly so stuff could happen. Though physics sort of fails on the specifics. (Why didn't it collapse into a black hole if it was basically a singularity? Hmm...) So in short, it's unknowable if an \"outside\" exists, and all we are capable of being aware of at this time is our own visible universe. But we'll have to see where science takes us."
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7ns500 | The moon’s gravity can visibly affect tides, but not the water in a glass. Why is this? | Repost | explainlikeimfive | {
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"text": [
"Given how much water is in the ocean, the few feet of tide isn’t really that much at all. If you scaled the ocean down to the size of a cup, the tides would be imperceptible.",
"Tides aren't just about the strength of the moon's gravity, it is about the *difference* in its strength. The gravitation pull at the left side of your glass isn't that much different than the right side. But with an ocean, one side can be thousands of miles further from the moon than the other. This *difference* in the pull cause the ocean to warp, which in turn causes the tides.",
"Same reason there are no tides on a small lake. The gravity change needs a massive 'bowl' for the effect to be noticeable. Tides are just the water sloshing around the world due to the changing pull of gravity. The moon pulls water a little closer to it. 5 feet of tides in an ocean that is thousands of feet deep isn't all that much. Now, the gravity at one end of a pond from the moon is basically the same at the other end because they are so close. Same as in your cup. The moon is 3 inches further away from one end of the cup than the other. Vs 25,000 miles for the earth. TL;dr: Much bigger volume in the ocean and much bigger difference in the distance between one side of the ocean and the other to the moon."
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7ns7m1 | Do our eyes have frame rates? why do things get blurry when they are moving fast enough? | Repost | explainlikeimfive | {
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"text": [
"No, your eyes do not have a frame rate. They work on analog signals, essentially. The blurring you seeing is caused by the way the rods and cones respond to light. It's a continuous image that you perceive not snapshots N times per second.",
"1^st Question: > Eyes work like an analog way, instead of digital way. > Therefore no. 2^nd Question: > Your eyes cannot track the object because it is moving too fast. > Therefore, your brain adds motion blur to the object."
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7nso9x | How do people become so addicted to alcohol they can’t go a day without it? | Repost | explainlikeimfive | {
"a_id": [
"ds488mb"
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"text": [
"Yarr! Yer not alone in askin', and kind strangers have explained: 1. [ELI5: Why can quitting drinking kill an alcoholic? ]( URL_0 ) ^(_54 comments_) 1. [ELI5: What is it exactly that alcoholics become addicted to? ]( URL_2 ) ^(_ > 100 comments_) 1. [ELI5: Why is alcohol supposedly very addictive, yet so few addicts are around (relatively)? Explain addiction to me. ]( URL_4 ) ^(_56 comments_) 1. [ELI5:Why is alcohol regarded differently from other addictive substances? ]( URL_1 ) ^(_80 comments_) 1. [ELI5: How do people get addicted to alcohol? ]( URL_3 ) ^(_6 comments_)"
],
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"https://www.reddit.com/r/explainlikeimfive/comments/1kgx4h/eli5_why_can_quitting_drinking_kill_an_alcoholic/",
"https://www.reddit.com/r/explainlikeimfive/comments/3sni1z/eli5why_is_alcohol_regarded_differently_from/",
"https://www.reddit.com/r/explainlikeimfive/comments/3toln8/eli5_what_is_it_exactly_that_alcoholics_become/",
"https://www.reddit.com/r/explainlikeimfive/comments/1rt32a/eli5_how_do_people_get_addicted_to_alcohol/",
"https://www.reddit.com/r/explainlikeimfive/comments/2yclea/eli5_why_is_alcohol_supposedly_very_addictive_yet/"
]
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|
7nsy1r | Wattage, voltage, amperage, and resistance | Repost | explainlikeimfive | {
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"text": [
"Think water in pipes: Voltage = water pressure Amperage (current) = volume of water that passes a single point in the pipe within a given time Resistance = inverse of pipe width voltage (water pressure) = Current x Resistance Power = water pressure x volume of water that passes a single point in the pipe over time more pressure through a given pipe diameter equals more flow, equals more power more voltage and less resistance equals more current",
"Joule (J) is a measurement of energy. Coulomb (C) is charge, basically A * s Voltage (V) is J/C. Energy per charge. Ampere (I) is C/s. Charge per second. WATT is V * I; J/s. Energy per second. Resistance is V/I. If we think of electricity as packets. C is the package. V is the size of the package. I is the speed the package travels. Resistance is the speed limit/size restriction through a component. Be aware, this is a super simplistic view and does not accurately portray how electricity works. It's just a way to sort of understand the values.",
"Compare it to a bus, with one elektron being a bus and the amount of people in the bus the energy that an elektron carries. Amperage would be the amount of busses that are driving. Voltage the amount of people per bus, wattage the total amount of people transported and resistance the amount of people a bus would lose going through an area. In more technical terms, Amperage is the amount of elektrons going through an area/point on a wire. Voltage the amount of energy that an elektron carries, Wattage the total amount of energy going through a point on a wire and resistance the amount of energy an elektron loses going through a part of a wire."
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|
7nt3fx | How was the speed of light determined to be 3*10^8 m/s? | Repost | explainlikeimfive | {
"a_id": [
"ds4bk09"
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"text": [
"It was measured. This began with Galileo who attempted to measure the speed of light with lanterns on hills. He concluded that the speed of light was very fast. Measurements continued and continue to this day. You can research the Michelson Morley experiments which found that the speed of light is not changed by the speed of the Earth."
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|
7ntvbo | How does laser eye surgery work? | Repost | explainlikeimfive | {
"a_id": [
"ds4g1y4",
"ds4fvgm"
],
"text": [
"Idk how the fuck it works but I'll tell you how it went for me. -tests done to see if I'm a candidate. -I wasn't a candidate for the \"best one\" so they opted me in for the \"2nd best\" -I said fuck it let's do this shit. -2 weeks with glasses because my eyes had scars (or some shit) due To contacts. -sign a bunch of shit so I won't sue em. -walk in (nervous as fuck) for the surgery. -they installed some metal eye opening stuff on my eyes so my eyes can't close. -they put numbing drops on my eyes. -some hydrating drops. -and more numbing drops. -Dr, optometrist, guy burning my eyes dude, touches my eyes. \"do you feel that?\". -\"hell the fuck no I don't! Let's get it on!\" -Green (not red laser like everybody expects) laser on my eyes for about 23.72 seconds each eye. -smell burning Fucking flesh!!! -close eyes, put on glasses, walk out with blurry vision and vicodin. -wake up (after sleeping Fucking 14 hours) with sensitivity to light for 48 hours, eyes crying for 48 hours... -i had to do steroid drops on my eyes (which taste like sour milk down my gullet) and hydration drops 3 to 17 times a day. -then after a week or so I got fucking 20/20 vision! -10/10 would do it again. Edited for drunken antincts.",
"They remove a really small piece from top of your eyes which is a \"lens\" that focuses incoming light. This makes the light go correctly where it's supposed to go."
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|
7ntzot | Guns and Sights | Repost | explainlikeimfive | {
"a_id": [
"ds4gls8",
"ds4gnf5"
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"text": [
"It's called [sighting in or zeroing]( URL_0 ) The sights can be manually calibrated by moving knobs on the optics themselves, causing it to aim down slightly so the barrel of the gun is pointed ever-so-slightly up. So when aiming at a distant target, your sights are directly on the target, but the bullet flies slightly up and falls through the air in an arc, before landing where you were aiming.",
"It's not just your barrel being lower. At extremely close ranges, this can pose a significant difference, but at longer ranges gravity also starts pulling your bullet down. The solution to this is that sights are ranged, and have built in or adjustable correction for these things - the technical term, I believe, being to 'zero' your shot. As you shoot further away, you need to aim the barrel further up to hit the same level above ground. So sights have settings for this - set to the range the target is approximately at - so that the point in the bullets parabolic trajectory intersects exactly with the point the sight is aimed. As visible on the top of this image - the striped line is the line that'd be looked along down the scope, the dotted line is the straight extension of the barrel, and the solid line is the path the bullet actually follows. URL_0"
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"https://defensivetraininggroup.files.wordpress.com/2015/03/battle-sight-zero.jpg"
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|
7nu3yq | - How are fuel prices at the pump determined and why do they fluctuate every day? | Repost | explainlikeimfive | {
"a_id": [
"ds4hmwq",
"ds4hdoz"
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"text": [
"If they think oil prices are going up, they raise prices. If they think oil prices are going down, they leave prices up to make more profit. If they think people will be travelling, they raise prices because of more demand. If they think people won't be travelling, they raise prices because of too little demand. About the only time prices go down is when there's a national election.",
"I am certainly no expert, but from what I understand it's the cost of crude oil, which is affected by various things, such as geopolitical issues. As far as I know most other costs are fairly fixed; taxes, marketing, transport, etc... So the fluctuations at the pump are due to fluctuations in the price of the raw product. But other things can come in to play as well. Here is a good [article]( URL_0 ) explaining the factors."
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"https://www.google.com.au/amp/s/amp.businessinsider.com/factors-that-determine-gas-price-2012-5"
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|
7nzl0w | Why does the earth being 1 degree warmer so significant? | Repost | explainlikeimfive | {
"a_id": [
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"text": [
"> If the weather was warmer by a degree on average every day there would be no difference. Well, that isn't what is being talked about. Instead think about how much energy is required to heat up the entire atmosphere and surface of Earth by one degree. A huge amount! That much energy being at work in the atmosphere can mean more powerful weather effects in the short term or in a specific area. Also think about how it gets colder as you move toward the poles. At some point water starts to freeze to ice. Now if you raise the overall temperature by one degree this would mean that point where water freezes consistently would move closer to the poles by some amount. As the change is very gradual this might mean like 100 miles, in a strip all the way around the planet for both poles. How much area is that?! And it isn't like that line is always in the same place throughout the year so ice melting at different times than normal can translate to unpredictable changes in the weather."
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|
7o0h9a | What happens to dead birds? How come we don't see them dropping from the skies when they die and we don't see millions of dead birds all over the place? Where do they all go? | Repost | explainlikeimfive | {
"a_id": [
"ds5w71g",
"ds5wbbq"
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"text": [
"Other things eat them. Vultures, raccoons, foxes, rodents, insects, etc. Nature has a cleaning crew.",
"Why would they be dropping from the sky in large enough amounts for you to notice? Those that are ill or otherwise dying are likely not able to fly. Why would we see millions of them all over the place? Corpses are scavenged and decompose, like all other dead animals."
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|
7o1fdq | Why does food taste weird after brushing your teeth? | Repost | explainlikeimfive | {
"a_id": [
"ds64ju6"
],
"text": [
"My guess would be the minty aftertaste. Same reason it tastes funny after chewing gum. I’m probably wrong but I figured I’d throw in my 2 cents"
],
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|
7o1glf | Why are people screaming Fake News when yellow journalism has been around as long as we can remember? Are they different? | Repost | explainlikeimfive | {
"a_id": [
"ds63f7g"
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"text": [
"Yo ho ho! Yer not alone in askin', and kind strangers have explained: 1. [Why has the term \"fake news\" become so popular lately? Didn't we already have words for that - lies and/or propaganda? ]( URL_2 ) ^(_13 comments_) 1. [Why did it take until 2016 for fake news to enter common slang terms and become part of popular culture? ]( URL_0 ) ^(_._) 1. [ELI5: Why was \"Fake News\" added to the dictionary this year when its just made of two standard words being used appropriately? ]( URL_1 ) ^(_6 comments_)"
],
"score": [
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"https://www.reddit.com/r/NoStupidQuestions/comments/7fxkvb/why_did_it_take_until_2016_for_fake_news_to_enter/",
"https://www.reddit.com/r/explainlikeimfive/comments/7cvoy2/eli5_why_was_fake_news_added_to_the_dictionary/",
"https://www.reddit.com/r/NoStupidQuestions/comments/7jt3pn/why_has_the_term_fake_news_become_so_popular/"
]
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|
7o2nkk | why were dinosaurs much larger than most animals we see today? | Repost | explainlikeimfive | {
"a_id": [
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"text": [
"the oxygen theories posted as other comments applies to insects, not dinosaurs. URL_1 the following theories are not mutually exclusive (meaning it's not #1 or #2, it could be #1 *and* #2 etc.). and tl;dr **we don't know for sure**, all the theories are controversial. theory #1 for dinosaurs: the mesozoic era (~250 million years ago - 65 million years ago, the time period all dinosaurs lived in) had much higher levels of carbon dioxide (co2) in the atmosphere. more co2 = higher temperatures. plants feed (via photosynthesis) off of co2, and higher temperatures promote more vegetative growth. the theory is that some dinosaurs were so big simply because there was so much for them to eat, which would explain why some herbivores were much larger than carnivores. note that the only dinosaurs that were small were carnivores, almost all herbivores were taller than 1 meter. this theory is also being challenged though ( URL_2 ) theory #2: hugeness was simply an evolutionary defense mechanism theory #3: if dinosaurs were cold blooded, as many paleontologists believe, their size could be a way to maintain their internal temperatures despite environmental circumstances. \"a house-sized, homeothermic Argentinosaurus could warm up slowly (in the sun, during the day) and cool down equally slowly (at night), giving it a fairly constant average body temperature--whereas a smaller reptile would be at the mercy of ambient temperatures on an hour-by-hour basis.\" ( URL_0 ) see also URL_3 theory #4: larger size = lower metabolism, longer digestion = bigger dinosaurs need less food. there's probably more out there, but these were the main ones that i found on google.",
"Higher oxygen content in the air allowed animals to grow to a much larger size. Their hearts didn't have to work as hard to pump oxygen through their body because there was more of it."
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"https://www.thoughtco.com/why-were-dinosaurs-so-big-1092128",
"https://news.nationalgeographic.com/news/2011/08/110808-ancient-insects-bugs-giants-oxygen-animals-science/",
"http://www.pnas.org/content/109/26/10403",
"https://www.livescience.com/5527-dinosaurs-big.html"
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|
7o3sqq | How do snails make their shells? | Repost | explainlikeimfive | {
"a_id": [
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"text": [
"Shells of things like snails and clams have shells made (primarily) of calcium carbonate. There's some protein in there too, but it's just a chemical that their bodies produce in a structured way over time. I guess it's analogous to how you grow hair or fingernails, but instead of growing the protein keratin they're putting down layers of calcium ions in a crystal lattice."
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|
7o3tmq | Game engines: what are they and why are new ones always needed? | Repost | explainlikeimfive | {
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"text": [
"So let's say you run a game studio that is making two very different games. One is a cute adventure game for kids where a princess has to rescue her animal friends from an evil witch. Another is a bloody shooter where a battle hardened soldier has to save the world from vicious aliens. Now, these games are wildly different thematically, but beneath the surface they both have a lot in common. They both need a way to render 3D graphics, as well as a 2D user interface. They both need to play music and sound effects. They both need to save and load the player's progress. They both need to detect collisions between the player character and the world around them. You don't want to do all that work twice, so you do it once and build it in a way that it can be used by both games, and possibly reused by others. This library of underlying tools and functionality is what you would call the game engine. New ones are needed for the same reason we need new anything. Sometimes the old ones just don't offer the power and flexibility that people want. A company may decide to make their own proprietary engine either because they aren't satisfied with what's available, or because they just don't want to pay to license what someone else made."
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7o9sjv | How pyramid schemes work | Repost | explainlikeimfive | {
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"text": [
"OP, I can sell you 100 plumbuses at 10 dollars a pop. If youre wondering what you would ever do with so many plumbuses, well you could sell 20 of them to 5 at other people at 15 dollars each, making you a hefty profit. Why would anyone buy 20 plumbuses from you? Well just tell them that they can sell 4 of them to to 5 other people at 20 dollars each, making them a nice profit for themselves too. Everyone wins."
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7oe4kn | Why do amplifiers read volume in negative decibels? | Repost | explainlikeimfive | {
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"text": [
"Decibels are used to measure sound volume, that's the usage of them that you are likely most familiar with. However, they are also a way of expressing a ratio. If you have a given signal strength, you can then express the strength of another signal in terms of decibels as related to that original signal. (Negative decibels would be weaker, positive decibels stronger) Most amp manufacturers aim to have a 0dB volume ratio mean \"as loud as we can get without distortion\", that is, super, super loud. You can therefore understand why most of the time we listen to the stereo, it is at negative decibels, i.e., weaker than \"as loud as we can get without distortion\"."
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7oerlt | Why is ice slippery? | Repost | explainlikeimfive | {
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"I was once told it’s due to the pressure from an object (a shoe, a tire, etc). The pressure creates a thin water barrier between the object and the ice surface and reduces friction significantly.",
"Typical ambient air temperatures will cause a thin layer of the water molecules on the surface of the solid ice to melt into liquid form. The layer of liquid water will cause things to be a little more mobile when they touch.",
"When you step on it, the pressure of your weight liquefies the top of the ice slightly, so you slide around on a thin layer of water. Notice that there has to be enough pressure or heat to melt it for it to be slippery.",
"These answers about pressure melting ice are a common misconception. If you look at the phase diagram of water you will see that it takes an absurd amount of pressure to do that. Ice is a lattice structure, and the top layer of molecules can’t fully participate in the lattice, so they can be thought of as liquid"
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7offqe | How does the tab under a rearview mirror dim lights when hitting it? | Repost | explainlikeimfive | {
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"It does indeed change the angle. The Mirror looks something like this: |\\ The left line being the mirror, reflecting all things behind you. The right line is the glass in front of the mirror, angled differently. When you press the button, the angle changes, to look like this: /| The mirror is now pointing downward and reflecting the headlights down, where they do not disturb your vision. Since it is probably dark/night you can now still see the much dimmer reflection of the glass instead.",
"I've searched tha seven seas fer an answer. Yer not alone in askin', and kind strangers have explained: 1. [ELI5: How \"flipping\" my car's rear view mirror makes it more dim (instead of just showing me my back seat). ]( URL_5 ) ^(_3 comments_) 1. [ELI5: How does the tab on my car mirror dim the reflection? ]( URL_3 ) ^(_1 comment_) 1. [How the fuck does my rear view mirror show the same exact image but dimmer when I pull the tab down? ]( URL_1 ) ^(_6 comments_) 1. [ELI5: How does the rear view mirror work after flipping it up at night? ]( URL_0 ) ^(_37 comments_) 1. [ELI5: Why tilting your rear-view mirror makes headlights dim. ]( URL_6 ) ^(_3 comments_) 1. [ELI5: The tab under my rearview mirror, when flicked, removes glare from headlights. How? ]( URL_4 ) ^(_8 comments_) 1. [ELI5: How does my rear view mirror get dim when I push the little tab on the bottom? ]( URL_2 ) ^(_2 comments_)"
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7ofshh | Can someone explain the year 2038 problem and what the consequences are exactly? | Repost | explainlikeimfive | {
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"text": [
"Yo ho ho! Yer not alone in askin', and kind strangers have explained: 1. [ELI5: The year 2038 problem. ]( URL_0 ) ^(_74 comments_) 1. [ELI5:Year 2038 Problem ]( URL_1 ) ^(_ > 100 comments_) 1. [ELI5: The year 2038 problem for computing systems? ]( URL_2 ) ^(_22 comments_) 1. [ELI5: The Year 2038 Problem ]( URL_5 ) ^(_20 comments_) 1. [ELI5: The Year 2038 problem ]( URL_4 ) ^(_6 comments_) 1. [ELI5:The 2038 problem. ]( URL_3 ) ^(_ > 100 comments_)",
"Computers run out of numbers for counting time. Basically current systems use 32-bit intergers to measure seconds then these seconds are added to 1/1/70 0001:01 and give the current time. Well in 2038 current systems won't be able to count any higher so it'll revert back 1. It's similar to the Y2K issue in which systems couldn't account for 2000. It's not really an issue. Every information system should be updated before then. Most are already compatible with 64bit intergers. The worst thing is that old Commodore 64 collecting dust will have the wrong time."
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7ok9xw | Now that we've found the Higgs Boson, what has it taught us about mass, or why objects have mass? | Repost | explainlikeimfive | {
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"Mass is a term claimed for how much an object interacts with the Higgs field. Think of water in a bucket. Each of the water molecules are interacting with eachother with hydrogen bonds. You stick your hand in the bucket, displacing water molecules around your hand. The Higgs field is exactly like water. But instead of water molecules there are little Higgs bosons. Thus if you have an object that interacts more with the Higgs field, then more Higgs bosons are displaced creating more mass.",
"It hasn't really taught us anything knew, it's confirmed some theories. The properties and impact were predicted by Dr. Higgs and his successors from the 1960s forward, the problem was just seeing if the thing actually existed.",
"As a preface, note that any layman-friendly explanation you will encounter here is going to be a gross oversimplification of the Higgs-mechanism, so take everything with a grain of salt (including this comment). To clear up some confusion that I've seen in this thread, first lets talk about something a little more fundamental, the Pauli-exclusion principle (PEP). It says that no two Fermions (particles that ordinary matter is made up of) can occupy the same quantum state (i.e position, angular momentum, energy etc). This is why we expect some resistance if we're trying to squish something together, for example. Now, Bosons are different from Fermions. They don't obey the PEP and as a consequence can be packed arbitrarily close together. This is for example why stating that particles gain mass by \"displacing\" Higgs-Bosons is not true, Bosons cannot be displaced. Anyways, back to your question. Particles gain mass by _interacting_ with an omnipresent Higgs _field_ that permeates all of space. The best way to think of this field is a room full of your friends (bear with me, this will all make sense in a moment). The people inside are _excitations_ of this room, much like the Higgs-Boson is an excitation of the above discussed Higgs field. Suppose now you want to go trough the room. Of course every single one of your friends will want to talk with you, slowing you down along the way. Meanwhile a complete stranger with the same path would get to their destination much faster, as only few people would slow them down with a conversation. A similar thing happens with particles. Their coupling strength (or popularity, in our analogy) determines how drastically they're \"slowed down\". the more they interact with the Higgs field, the more mass they get and vice versa. As I mentioned above, this is not a complete rundown on the mechanism, but seeing as it nevertheless is a pretty lengthy wall of text already I will stop here. If you have any follow up questions, feel free to ask.",
"I am curious to see if we can manipulate the Higgs and make matter have more or less mass than normal. Imagine high tensile strength steel wires that are a couple inches thick and yet per foot of length weighs the same as spider silk. More a what if than a reality"
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7omwsl | Why can we make bluray versions of old movies that look better but cant make better quality versions of old songs? | Repost | explainlikeimfive | {
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"text": [
"We can and they do. And they do it in pretty much the exact way that they restore films. They go back to the original recordings, clean them up, and remaster them.",
"The general principles behind releasing anything of higher quality is that you can't improve what you don't have. With movies, they were shot on film which is way higher quality than you might think. They simply have the information to work with and their only limiting factor is the medium that you are producing for. Note for things shot on videotape, you don't get better quality, often times you get worse Older songs though have different issues given the medium that they were recorded to with mediums that weren't as high quality as you think. But there is a wide variety of mediums and techniques used in recording and that limits you since your master can vary so much. SO if your source was good enough for the medium of the era, you are going to have to go through a lot of work to clean it out and if your source is crap, you can only do so much. TLDR - different mediums over time with different levels of quality."
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7ou27k | If your skin is constantly growing and shedding off of your body, then how are tattoos permanent? | Repost | explainlikeimfive | {
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"text": [
"The outer layer of your skin is sloughed off constantly, yes. But tattoos deposit ink deeper than this, where it's not shedding off."
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7oydhz | When you have an internal organ removed, what does your body do with all of the new space in your chest\abdomen? | Repost | explainlikeimfive | {
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"Generally it closes the hole back up with fluids or meatstuff. In the event of a kidney removal, for example, the hole just closes up over the course of a few months. In the event of a partial brain removal, cerebrospinal fluid fills in the hole. Our bodies don't enjoy having holes in them, so they do a pretty good job of tidying it up."
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7p1fw1 | Why do certain smells get stuck on clothes? | Repost | explainlikeimfive | {
"a_id": [
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"text": [
"Yo ho ho! Yer not alone in askin', and kind strangers have explained: 1. [ELI5: Why do smells \"cling\" to you? ]( URL_8 ) ^(_2 comments_) 1. [ELI5: What makes clothing hold onto certain odors? ]( URL_5 ) ^(_1 comment_) 1. [ELI5:Why do some smells stay on clothes? ]( URL_6 ) ^(_1 comment_) 1. [ELI5: Why does the smell of Indian food stick to me so greatly? ]( URL_0 ) ^(_1 comment_) 1. [ELI5: How can the smell of cigarette smoke stay in walls, curtains, clothes, etc. for long periods of time, but smells like perfumes, casseroles, other foods, etc. do not linger for more than a couple of days usually? ]( URL_7 ) ^(_ > 100 comments_) 1. [ELI5: Why does the smell of smoke \"stick\" to you? ]( URL_1 ) ^(_2 comments_) 1. [ELI5:Why do clothes put away in storage come out with a smell? ]( URL_4 ) ^(_ > 100 comments_) 1. [ELI5: Why do some odors attach to clothing and some don't? ]( URL_3 ) ^(_3 comments_) 1. [ELI5: How do things (like your body or clothes) absorb odors and smells? ]( URL_2 ) ^(_1 comment_)",
"When you smell something, what you're actually smelling are gasses and particles given off by the thing you're smelling. With some smells, like smoke, the gasses are accompanied by particles that get ingrained in fabric. Those particles continue to break down and become airborne, allowing the smell to linger far longer than anyone wants it to."
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7p2g2j | How is windchill measured? | Repost | explainlikeimfive | {
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"text": [
"It isn't measured. It's calculated. WC = 35.74 + 0.6215T – 35.75(V^0.16) + 0.4275T(V^0.16) Where T is temperature and V is wind speed.",
"Yer not alone in askin', and kind strangers have explained: 1. [ELI5: How is wind chill measured? ]( URL_1 ) ^(_1 comment_) 1. [ELI5:This is a little late, but explain how wind chill works. ]( URL_0 ) ^(_2 comments_) 1. [ELI5: How does wind chill work? ]( URL_4 ) ^(_10 comments_) 1. [ELI5: How do we know how much colder the windchill feels? ]( URL_3 ) ^(_2 comments_) 1. [ELI5: Wind chill ]( URL_5 ) ^(_12 comments_) 1. [ELI5: What exactly are the heat index and wind chill, and how wre they measured? ]( URL_2 ) ^(_1 comment_)"
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|
7p670m | why does detecting road signs prove I am human on the internet? | Repost | explainlikeimfive | {
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"text": [
"Most bots that try to steal accounts probably aren't set up to recognize road signs. Meanwhile, the captcha doubles as you helping train image recognition bots for self driving cars.",
"As with all \"captchas\", it's about making it more expensive for artificial intelligence to solve it. The goal is that it would cost more to have it solved than an unwanted access would yield in returns. Analyzing the pictures for road-signs is possible but currently (still) too complicated to be implemented in AI cheaply enough for it to pay off.",
"You feed an AI a few million pictures and tell it thats signs. And a few million other pictures and tell it thoes are not signs. But you want to be able to use the same AI for other stuff than just signs. As an example, telling dogs from bees. AIs have great dificulty telling things apart that are edge cases. A [dog in a bee suit]( URL_1 ) a human would be no problem for a human. Or what if you looked at a blury image? Or a drawing perfaps? That said CGP Greys video [How Machines Learn]( URL_2 ) (and the [follow up video]( URL_0 )) explains it better than I ever could if you have 10mins to spend < 3",
"There is a little more to it that other comments haven’t addressed. The software you are talking about is called [reCAPTCHA]( URL_0 ) If you look at the images there you will recognise the older version with suspicious looking book text. The system works on guessing and learning. reCAPTCHA doesn’t know the 100% correct answer - but it can guess close enough. If your answer matches its guess close enough, then you pass. It then looks at all the data it has collected from everyone answering the same specific questions with the same specific images, and the software looks at trends of the most common answers. It accepts that as correct, and updates its algorithms to be more correct in future. When you use it, you are teaching Google’s computers how to identify road signs better in future. The older style one with text was really cool, Google wants to have every book ever stored on its computers, and stored as text, not just scans of books. Whenever the algorithm came across a word it didn’t know - usually due to either poor quality scans, or print errors or wear and tear on books, it would include it in a reCAPTCHA, along with a word it was sure about. Eventually by collecting everyone’s answers, it was able to learn how to read that word. This is called Machine Learning. No person anywhere can write a computer program to correctly identify road signs, but a computer can be given an insanely large amount of data (the squares you do and don’t click on) and be told to use that data to come up with its own algorithm for identifying road signs. Every time you do and don’t click a road sign, it compares it to its algorithm, and it then either decides you are wrong, and therefore you fail, or it’s algorithm is wrong, and it makes a minor change and it won’t make the same mistake next time. I think eventually we will see this implemented in to Google Maps were Google can read every road sign."
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|
7p6lpt | Why are upload speeds significantly lower than download speeds? | Repost | explainlikeimfive | {
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"text": [
"In short, because ISPs (Internet Service Providers) prioritize download speeds rather than upload speeds. This is because they assume most people are downloading than uploading."
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7pcc9y | I have a question on Ohms and Speaker impedance. | Repost | explainlikeimfive | {
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"text": [
"Speaker impedance is ohms, they're the same. They represent the resistance in the coil of the speaker. If its too low it'll try to pull more current than the amp can handle, too high and the amp won't be able to deliver enough power to it. You want the Ohms/Impedance of your speakers to be within the range that the amplifier supports, and you want their power rating to be greater than or equal to the amp. An amp that can provide more power than the speakers can handle can burn them out."
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7pegqv | Why earth maps have always been drawn with the "North up / South down" orientation? | Repost | explainlikeimfive | {
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"text": [
"They haven't been, the key was the word orientation. There was a time they were organised facing the orient, or east.",
"Because it was more convenient for the people who drew them: 1. Most of Earth's landmass and population is in the Northern hemisphere. 2. The people who drew these maps are mostly Europeans, which is also why Europe is in the middle.",
"I feel like we used the stars to navigate at one point, using the north star as a reference of true north. Plotting a course relative to something that's always north probably reduced the amount of lost or missing verses at one point",
"Until the sixteenth century most maps had east on top. When compasses began being widely used, it made sense to align the map to the compass. When you're you're looking down at your compass pointing straight in front of you, you are facing north. So the map is drawn to align to a north facing person."
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7pepag | How film editors used to edit movie in older times without computers? | Repost | explainlikeimfive | {
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"text": [
"By literally cutting and taping together pieces of the film. At first they would do this completely by hand, later on [machines that helped with editing]( URL_0 ) were created.",
"Old movies were filmed on celluloid film reels, in the editing room directors would cut scenes... merge footage and change colours literally on the reel rather than through digital processing. A good movie that proves a quick demonstration of how it used to work is Fight Club, when Tyler Durden does some film editing at a cinema. Some directors still use this approach, Christopher Nolan, Quentin Tarantino"
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7pjdfm | Why have Jewish people been persecuted so much historically? | Repost | explainlikeimfive | {
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"text": [
"Early Christian edicts stated that Christians were not allowed to collect interest on loans. Because of that, there was no incentive for any Christian to make any loans--since they will risk not getting the money back for no potential gain. Jews did not have this restriction, therefore they became the bankers. If a King or Duke needed extra funds for something immediate, they had to go to a Jew. This made many of them rich (since interest is a good way to make money) and unpopular (since nobody likes paying interest). This then makes them a target--if your debt gets too high or if you think confiscating money is the best way to get quick cash, use them as a scapegoat for whatever dastardly rumor you want.",
"For a lot of European history the Jews were an insular but also obvious minority. They spoke a different language, lived in separate communities, practiced a foreign religion, and dressed and acted in strange (to European Christians) ways. Jews were also often relegated to undesirable professions (itinerant trading, money lending, etc) due to prohibitions on them owning land or settling in certain areas. All of this made them easy targets for scapegoating, especially in a time when for the vast majority of people their only real interaction with the world outside their village was through the Catholic Church."
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|
7pky8j | why do cold symptoms seem stronger/worse later in the day or before sleep as compared to during the day when you’re active? | Repost | explainlikeimfive | {
"a_id": [
"dsi2vqn"
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"text": [
"Your immune system has a circadian rhythm much like your sleep cycle. During midday, functions related to cell immunity—antibody production and macrophage activity—dominate. During the night, these ramp down in favor of discomforting—but healing—inflammation functions. [Source (just googled)]( URL_0 )"
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"http://m.huffingtonpost.ca/jason-tetro/colds-flu-worse-at-night_b_14303482.html"
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} | [
"url"
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|
7pmyqg | How do record players turn physical rivets into any possible sound from any instrument? | Repost | explainlikeimfive | {
"a_id": [
"dsigvr4",
"dsihfk5"
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"text": [
"Every sound from every instrument is, at its simplest level, air vibrating at a specific frequency. If you can reproduce that exact frequency, you can produce the sound of anything you want: instruments, animals, speech, whatever. As a record needle bounces within the grooves of a record, it's picking up those vibrations and sending the signal to the speaker, which pumps out the frequency of the sound.",
"all sounds are just little vibrations in the air, and all those vibrations add up to make a single wave at any given moment. the microphone is hit by the wave and converts it into electrical pulses. those electrical signals are then converted into mechanical power, which cut the master disc in a pattern. through some manufacturing wizardry, the master is used to create the vinyl record. when set to play, the grooves in the vinyl push the needle around, causing it to close an electrical circuit, reproducing the same electrical pulses the microphone created when it was recording. those signals are amplified and sent to the speaker, which then pushes air."
],
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|
7po4ff | What is that ear hurting noise that happens when you have one window of the car open while driving fast? | Repost | explainlikeimfive | {
"a_id": [
"dsioevp",
"dsio2id"
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"text": [
"If you have a large volume of air with a small hole to the outside, the air can start to resonate. That means that air is pushed inside by the motion of the car, increasing pressure inside your car. The rising pressure will stop more air from rushing in, and then push it back back outside. This process repeats over and over again at a very rapid pace, creating a loud noise. It's the same effect that makes a sound when you blow over an open bottle, or helps increase the volume of subwoofers through bass reflex holes. The technical term for this is [helmholtz resonance]( URL_0 ).",
"It’s called wind buffeting, and happens when your open window interrupts the aerodynamics of the wind tornados passing over the sides of your car as you move."
],
"score": [
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"text_urls": [
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"https://en.wikipedia.org/wiki/Helmholtz_resonance"
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|
7pq2um | How come you can hold your bladder for hours, but as soon as a toilet enters your vision it feels as though you’re going to explode? | Repost | explainlikeimfive | {
"a_id": [
"dsj44i9"
],
"text": [
"Your brain is what's suppressing the urge to urinate when it knows that there's no chance of urinating at the time. Once you're near a toilet, the suppressing wears off, and you feel the full urge to urinate. You can think of it as a measure to ensure that you take the opportunity to urinate when you can."
],
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7ps7tb | why can we often “feel people staring at us”? I have woken up at times because I could feel someone staring at me. Is there any science behind this? | Repost | explainlikeimfive | {
"a_id": [
"dsjmef9"
],
"text": [
"There is *psychology* behind it. Often you notice someone is around you because of faint noise, change in air currents, lighting, or temperature. The brief alarm over discovering someone often overwhelms the sensation that caused you to notice them in the first place. Also, there is a lot of confirmation bias here. If you wake up and someone *isn't* staring at you, it won't make much of an impression and you likely won't remember. In fact, it isn't unusual to wake up at nice and go back to sleep with no long-term memory of it. You only take note of those rare times someone was actually there."
],
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|
7pt20u | Why is a small amount of inflation considered good for the economy? | Repost | explainlikeimfive | {
"a_id": [
"dsjtqeg",
"dsjtf88",
"dsjtxab"
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"text": [
"You want some inflation to discourage currency hoarding and lower the effective cost of borrowing. If your money is never losing value, why risk investing it? Put in in your Scrooge McDuck vault. But if it's losing 2% a year, now you better get moving. For your average person 2% a year isn't a big deal, but for institutions that deal in billions that equates to a vast sum down the toilet if they don't keep their money pile moving. Inflation helps keep the cash flow going in a modern economy. Now for your average person, you don't have much in savings but you probably do have a mortgage. A thirty year mortgage. Over thirty years, inflation puts a real dent in the effective cost of the mortgage, and makes it cheaper for you to borrow money long term. Your payments don't change, but they're worth less every year.",
"Ahoy, matey! Yer not alone in askin', and kind strangers have explained: 1. [ELI5: Why is a small inflation rate considered good but not, say, a small deflation rate? ]( URL_0 ) ^(_34 comments_) 1. [ELI5: Why is inflation good for an economy? ]( URL_4 ) ^(_6 comments_) 1. [ELI5: How is slow but basically unlimited inflation sustainable or even good for the economy? ]( URL_8 ) ^(_4 comments_) 1. [ELI5: Why is inflation considered good thing? ]( URL_3 ) ^(_22 comments_) 1. [ELI5: In a healthy or growing economy, is inflation inevitable? Is inflation necessarily a bad thing? ]( URL_7 ) ^(_2 comments_) 1. [ELI5: Why is there constant inflation of currency? ]( URL_2 ) ^(_15 comments_) 1. [Why is inflation considered a good thing? ]( URL_5 ) ^(_30 comments_) 1. [ELI5: Why is moderate inflation considered a good thing ]( URL_6 ) ^(_9 comments_) 1. [ELI5: Economic inflation. Why does money consistently decrease in value? ]( URL_1 ) ^(_15 comments_)",
"Small amounts of inflation encourage spending and investment. If you're money becomes more valuable over time (as it would under a deflation), then why buy a house/TV/Car now, when you're dollar will be worth more next year? Or why take your money out of the bank and invest it? You're basically able to make money by just burying cash in your backyard. So why risk the market goes down? Why would a bank lend out money? Who needs to take a risk that lendee won't be able to pay it off? You're gaining value by letting it sit in your vault. All of these things lead to shitty economy, less spending, less movement of money, less jobs, and overall a worse standard of living. A small, controlled amount of inflation helps stimulate the economy."
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"https://www.reddit.com/r/explainlikeimfive/comments/6gsoox/eli5_why_is_a_small_inflation_rate_considered/",
"https://www.reddit.com/r/explainlikeimfive/comments/6t1p0i/eli5_economic_inflation_why_does_money/",
"https://www.reddit.com/r/explainlikeimfive/comments/1qemc1/eli5_why_is_there_constant_inflation_of_currency/",
"https://www.reddit.com/r/explainlikeimfive/comments/5l9yzq/eli5_why_is_inflation_considered_good_thing/",
"https://www.reddit.com/r/explainlikeimfive/comments/3o36ei/eli5_why_is_inflation_good_for_an_economy/",
"https://www.reddit.com/r/explainlikeimfive/comments/1tzybb/why_is_inflation_considered_a_good_thing/",
"https://www.reddit.com/r/explainlikeimfive/comments/5ns0qz/eli5_why_is_moderate_inflation_considered_a_good/",
"https://www.reddit.com/r/explainlikeimfive/comments/43b7cy/eli5_in_a_healthy_or_growing_economy_is_inflation/",
"https://www.reddit.com/r/explainlikeimfive/comments/2h4j48/eli5_how_is_slow_but_basically_unlimited/"
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7pvk05 | Why is it that you when plug in a MacBook with a dead battery it instantly turns on but with an iPhone it takes time? | Repost | explainlikeimfive | {
"a_id": [
"dskcaa8"
],
"text": [
"Laptops are designed to run directly on mains electricity, so the electricity goes to the laptop and the battery is charged in the process. So even if you remove the battery the laptop will still turn on. But phones are designed to be only portable so all power goes to the battery and then to the phone."
],
"score": [
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7q01cg | How do electronics lose charge while not being used? | Repost | explainlikeimfive | {
"a_id": [
"dslbrqw",
"dslde72"
],
"text": [
"The chemical reactions in batteries don't stop, even when not in use. As time goes on, this reduces the free charge and capacity of the battery. Most batteries nowadays are relatively efficient when not in use, but there will always be a small drainage of energy over time.",
"Some electronics never fully turn off, they're in low-power mode to keep internal clocks, infrared detector, etc. active."
],
"score": [
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7q1sym | What really determines stock prices? | Repost | explainlikeimfive | {
"a_id": [
"dslsgim",
"dslqyfp"
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"text": [
"**In theory:** The price of a stock is the net present value of all future dividends to be paid on that stock. Since this is ELI5, I can break that down a bit more. A \"dividend\" is a portion of a company's profits that is paid to shareholders. Some companies pay dividends every year, others (often tech startups) will go decades without paying a single dividend. No successful company can go its entire existence without ever paying dividends. Microsoft was founded in [1975]( URL_3 ) and paid its first dividend in [2003]( URL_2 ). Amazon was founded in [1994]( URL_1 ) and still [hasn't paid]( URL_0 ) a dividend. Stocks can have high prices even when they don't pay dividends because it isn't the current dividend that matters, it's the value of all dividends in the future. So, Amazon's stock price is currently $1300 because people expect that all future dividends to be paid on each share of stock will total $1300. We say \"net present value\" because money today is worth more than money tomorrow, so we consider that as part of the calculation; e.g. a $50 dividend paid out a decade from now is only worth $41.01 today, assuming 2% inflation, therefore that $50 has a \"net present value\" of $41.01. **In practice:** Occasionally, short term fluctuations have easy explanations. Did Apple report lower earnings than expected in the second quarter? Their stock price will go down, because lower earnings mean lower dividends. Note that what matters isn't their actual earnings, but the difference between their expected earnings and their actual earnings. This is because, before the earnings report, knowledge of the expected earnings is already included in the stock price. Similarly, a company issuing a recall or announcing that a new product will go to market sooner than expected will expect a quick change in stock price. The stock market is a market. The price is where the supply and demand curves meet. Short term changes in that price are almost completely random (with notable exceptions, listed above). Medium term changes in that price are highly correlated with (people's confidence in) the overall health of the economy or the specific industry of which the company is a part. It is only in the long term that the theoretical relationship between dividends and price holds. And, in the long term, we're all dead. EDIT: u/Phage0070 has helpfully pointed out that I forgot to mention that the assets of a company (and its expected future assets), such as the computers and manufacturing equipment it owns, are also included in the theoretical value of the stock price. This is because if the company were to suddenly stop existing the shareholder could still recoup value by selling off those assets.",
"supply and demand. there's millions of potential buyers with varying levels of demand. there's millions of potential sellers with varying levels of supply. each buyer and seller's level of demand or supply isnt' static. it changes on whims, ideas, guesses, emotions, opinions and etc. if Adam wants to buy widget for $1 but Betty is willing to pay $1.10 for it, and Will has a widget and is willing to sell no less than $1.50 but Yolanda has the same widget is willing to sell for $1.10, then Yolanda sells the widget to Betty for $1.10. Yolanda gets $1.10-broker fees and Betty gets the widget-broker fees. And Adam doesn't get anything and Will still holds his widget. and the broker's board has the last price of the widget as $1.10"
],
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"text_urls": [
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"http://www.dividend.com/dividend-stocks/services/department-stores/amzn-amazoncom-inc/",
"https://en.wikipedia.org/wiki/Amazon_\\(company\\)",
"https://www.wsj.com/articles/SB1042311223645379424",
"https://en.wikipedia.org/wiki/Microsoft"
],
[]
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} | [
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|
7q3y4u | Why does our taste in food change during our lives? | Repost | explainlikeimfive | {
"a_id": [
"dsm6ov3"
],
"text": [
"It's my understanding your taste buds actually start to fade. When your a child things are that much more intense tasting. As an adult they begin to regress and start dying off. Be interesting to get a real scientific answer though, just something I remembered reading somewhere"
],
"score": [
8
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"text_urls": [
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} | [
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|
7q4mk2 | If human cells get changed so often, why do scars retain for a long time? | Repost | explainlikeimfive | {
"a_id": [
"dsmc28b"
],
"text": [
"Imagine your body as a house where the blueprints were lost during construction. One day, the neighbor's kid manages to smack a baseball through a window. It's pretty easy to tell that there is a shattered window that needs replacement within a window frame even without the blueprints. You get some new glass, install it, and the house looks as good as new. Now, think of the damage if a distracted driver plows a truck though the wall to your living room, taking out a large chunk of wall and an entire window frame. Your first concern is to seal the hole so that the inside of your house is not exposed to the outside. With the hole sealed, you realize that you don't remember what the original wall and window looked like and you don't have the blueprints. You can repair what you can based on the edges but it may look very off both physically and functionally. The seal probably lacks the same insulation and the actual window, but at least nothing can get in or out. This is a scar. Your body only can regenerate (repair back to the new state) parts when it knows what it is based on its surroundings. If it takes too much damage, it won't be able to correctly regenerate and seals it with a scar. The cell replacement acts constantly but can only swap out what is already there. Since there are no blueprints, it cannot make what it doesn't know."
],
"score": [
5
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"text_urls": [
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|
7q7dj6 | If a person jumped into a hole that began on one side of the globe and stretched to the other side would they fly into the air while exiting the hole or would they land safely on their feet? (Assuming no obstructions in the hole) | Repost | explainlikeimfive | {
"a_id": [
"dsmwivx"
],
"text": [
"Neither. Assuming that you ignore the fact that the temperature and pressure in the middle of the earth would kill them, they'd make it most of the way to the other side, but then start falling back down the way they came. They'd get even less close to the entrance where they jumped in, and switch directions again. They'd oscillate back and forth like that for a while before eventually settling into the center of the earth, weightless, and unable to escape without climbing the walls. This is because friction with the air will slow them down during their fall and subsequent ascent."
],
"score": [
3
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"text_urls": [
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|
7q9332 | When a new tech interface standard comes out (USB 3.1, HDMI 2.0, Thunderbolt 3), what is changed that makes it faster? | Repost | explainlikeimfive | {
"a_id": [
"dsnbmjv"
],
"text": [
"The protocol on the wire gets changed. Usually a combination of a faster clock rate because of better/faster chips on the interface cards and more efficient methods of transmission. Look at 100mbps fast Ethernet vs 1 gigabit Ethernet. Same cables, but different modulation techniques and thus different speeds."
],
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|
7q9oly | Why does milk help when you eat spicy food? | Repost | explainlikeimfive | {
"a_id": [
"dsnhnoi",
"dsnh5gt"
],
"text": [
"Right! The capsaicin which causes the spicy feeling on your tongue binds with casein in the milk so you don't feel it anymore",
"I think the fats in the milk bind the either the chemical that causes the spice, or the nerve endings that would feel it, i kinda forget which."
],
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|
7qbvlj | Why can't light penetrate walls but radio waves can? | Repost | explainlikeimfive | {
"a_id": [
"dsnyo8b"
],
"text": [
"It has to do with how EM radiation interacts with materials, and on how that depends on wavelength/frequency/energy of it. Quick little excursion into quantum mechanics. Photons come in discrete packets (quanta), and the energy of the photon determines its wavelength and frequency. The reverse statement is also true, if you have a photon of a certain wavelength/frequency then it must have the corresponding energy. 100 MHz radio means the photons have ~4*10^-7 electronVolts of energy. Red visible light photons meanwhile has an energy about 2 eV. Very high energy gamma rays can push 100 Tera electron Volts. Shorter wavelength/higher frequency=more energy Energy when dealing with subatomic particles is also quantized. Atoms and molecules absorb energy in discrete packets (quanta) and can only deal with energy that comes in packets of the right size. If a photon doesn't have enough energy to cause it's state to jump from a lower energy to a higher energy, it doesn't sit around waiting for another photon to come along and then add the energy of the two photons, it just doesn't interact at all. I should probably mention conducting materials as well. If you have an oscillating electromagnetic field (which is what EM radiation is) near something conductive, you'll find a current develops in the conducting material in response. This takes energy out of the electromagnetic field, reducing the intensity of the radiation. This is how antenna work, but anything conductive in the way will do the same, which is why your wifi is a bit spotty in the bathroom (all those pipes). Radio waves are very low energy. This means they simply fail to interact with most material. It can, but it will take quite a bit of it to do so. While conductive material in the walls will reduce it's intensity, radio waves wavelength can be quite large (that 100 Mhz is has a wavelength 3 meters ) which effectively lets it go around things like concrete pillars with rebar in them, or some pipes. Visible light meanwhile is much more energetic, and can interact with most solid material. So it gets absorbed and either gets scattered off randomly. It just can't make it through. However you can also create situations where radio waves can't get in, but light can. [A Faraday Cage]( URL_0 ) is the classic example. The complete cage of metal bars means it's impossible for radio waves to go around, so it interacts with the metal in the cage, and can't make it through. Visible light meanwhile has a wavelength much much much smaller than the holes in the cage, allowing it to pass right through the holes and never notice the cage is there."
],
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|
7qbys6 | How does a knife cut through material on atomic/molecular level? | Repost | explainlikeimfive | {
"a_id": [
"dsnylg8"
],
"text": [
"They push atoms out of the way. I know its a really common fact that atoms never touch eachother, but you have to understand that on the scale that that is true it never ever impacts anything practical. Its like if I showed you a stacked stone wall and said \"here run through this, don't worry, those stones aren't technically connected.\" But atoms are connected on a macro level, and the knife can break these intramolecular bonds as it passes through."
],
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|
7qc022 | Why is it you can think of a word and use it properly in a sentence even though you can’t recall what the word means? | Repost | explainlikeimfive | {
"a_id": [
"dso1unk"
],
"text": [
"Because you've heard or seen it used in that type of context, so you are essentially imitating without understanding. In vocabulary tests, constructing a sentence using a word correctly is taken as a sign that the comprehension of the meaning is there."
],
"score": [
3
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"text_urls": [
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|
7qfsx8 | What Is the Concern with the Use of Mobile Phones on Aeroplanes? | Repost | explainlikeimfive | {
"a_id": [
"dsoufqm"
],
"text": [
"There were (are) two main concerns - that cellphones and other wireless devices can interfere with radio communications onboard the plane, and that they can cause interference and confusion within ground network operations. Even though there's no evidence that this has ever happened, the FCC and FAA still preferred to play it safe since theoretically all communications devices involved operate on radio frequencies and that has the potential to cause interference... even though they're at drastically different frequencies. Also there was a time when people considered cellphone usage on planes to be rude, but I think in the last 15 years or so people have given that attitude up."
],
"score": [
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"text_urls": [
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} | [
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|
7qlsvz | Why does rapid changing weather cause people to get sick? | Repost | explainlikeimfive | {
"a_id": [
"dsq6kui"
],
"text": [
"The simple answer to your question is that it doesn’t. There is no evidence that temperature changes make one sick. Instead, people likely make false correlations (X% of people get sick on any given day and some of those days have temperature changes) or other factors that happened with a temperature change — plants blooming in spring, a cold front that brings new allergens in the air — are actually a cause rather than the temperature change per se."
],
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|
7qohx4 | The differences between Suni, Shia, and Kurdish muslims in the Middle East and the conflict(s) surrounding them. | Repost | explainlikeimfive | {
"a_id": [
"dsqp8aq"
],
"text": [
"The Shia and Sunni are the two main branches of Islam, and concern the proper line of descent from Muhammad. The Sunni believe that the rightful heir was Abu Bakr, Muhammad's father-in-law, while the Shia believe it was Ali, Muhammad's son-in-law through his daughter Fatima (hence why the Shia are historically sometimes referred to as the Fatimids, particularly in Egypt prior to the rise of Saladin). In addition to the above, there are also ethnic tensions associated with the Shia/Sunni split, as Arabs (and Muslims in general) are overwhelmingly Sunni, while Iranians are Shia. There are ethnic tensions between the Arabs and Persians/Iranians that date back far before Islam was founded, and that continued into the modern variant that's primarily Sunni Saudi Arabia vs. Shia Iran. The Kurds are a mix of the two (although they are largely Sunni), in addition to other ethnic groups like the Yazidi that are generally held by the Muslim Kurds to be fellow Kurds, and are an ethnic group sandwiched between Turkey, Iran, Iraq, and Syria. Kurds basically want their own ethnic state, and have been oppressed for generations by their neighboring ethnic groups. As a result, Kurds are a bit more nationalistic than religiously-affiliated. The Kurds are also pretty heavily influenced by their diaspora, both in the US and the former USSR, which is part of the reason why they don't generally care as much about religious differences as other Muslim groups in the region. Beyond that, the Kurds are also in a particularly important region of the Middle East that's been influenced by essentially every single Empire in Western and near-Eastern history, including the Persians, Greeks, Romans, Byzantines, Ottomans, the various Crusader States, and the British, Russian, and French empires prior to WWII."
],
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|
7qp6lv | does sleeping late 2am and waking up late noon harm your body and age you prematurely? | Repost | explainlikeimfive | {
"a_id": [
"dsqv531"
],
"text": [
"The schedule you describe is not that unusual and will not cause you any problems. But living a truly 'opposite' schedule, like people who work a graveyard shift, [can have an adverse effect on your physical and mental health]( URL_0 ) but again, you are NOT at risk for this waking up at noon. You're fine."
],
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"text_urls": [
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"https://sleepfoundation.org/shift-work/content/living-coping-shift-work-disorder"
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|
7qp9gj | what is Escrow | Repost | explainlikeimfive | {
"a_id": [
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"text": [
"Depends on context, but in general 'escrow' means that a third party holds things and manages the transactions between the two main parties. The most basic example is a mortgage escrow account, where, if the account holder chooses, they can direct deposit a chunk of their wages into the escrow account managed by a bank or similar institution, and the bank handles paying all the bills related to the mortgage, like property tax, the mortgage itself, homeowner's insurance, etc, from the escrow account.",
"My bank collects an escrow payment with my mortgage payment each month, and then they pay my property tax and homeowner's insurance when they are due. Instead of having escrow I could choose to just pay these items myself, but that would mean a once-a-year payment of maybe a couple grand I would have to pay out of pocket. I just don't have the discipline to save up for these expenses myself.",
"Remember when you were a kid and wanted to trade something with a playmate you didn't quite trust? You'd play this little game where you would try to swap items at the exact same time so no one would wind up with both. If you really didn't trust each other, you might go find an adult who would ensure everything went fairly. Now imagine doing that same thing, but instead of trading a toy car for an action figure, you are buying a house from a stranger. Escrow is that adult, a neutral third party who keeps things fair. You deposit your money, plus a small fee, into an escrow account, where it stays until the house is transferred to you and you agree everything is in order. You can't try to swindle the seller out of the house because your money is already gone. And he can't try to take the money and run and keep the house because he doesn't have access to it. If there is a dispute, the money stays in escrow until it is resolved. Another common use of escrow is when the bank requires you to keep a certain level of insurance in your house while you still have a mortgage. They don't trust you because you could just not get insurance and just declare bankruptcy if your house burned down. And you don't trust them because they could just pocket the money and say \"what insurance?\" if your house burned down. Instead, you put a certain amount away in escrow, and the insurance gets paid out of that."
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7qpggt | why is there no thunder or lightning during a snowstorm? | Repost | explainlikeimfive | {
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"I've seen and heard lightning in a snowstorm. Worked at a ski resort as a lift operator, nothing more scary than lightning when you're sitting in a metal shack at the top of a mountain. The weather people call it *thundersnow*.",
"It's possible. Meteorologists call it \"thundersnow\", but it's pretty rare. I'm far from a weather expert but I can make an educated guess on why this is the case. Thunderstorms are caused when you have columns of warm, humid air clashing with cooler air. Since hot air is less dense, it rises, forming towering clouds. Daytime heating energizes this cycle, forcing more hot, unstable air upwards. The huge amount of energy in these clouds creates a strong convection current. Any particles within that current will collide building up a static charge, and you get lightning. Winter storms though just don't have that kind of energy. They tend to start life as cooler, dryer air moving across relatively warm bodies of water. They can suck up a huge amount of moisture, but without the daytime heating, there's just not enough energy to create the convection currents necessary to produce lightning. To get thundersnow, you have to have a line of storm cells move over top a layer of cooler air, where precipitation will turn into snow before it hits the ground."
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7qq7dq | What is Beta Decay? | Repost | explainlikeimfive | {
"a_id": [
"dsr2xy2"
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"text": [
"Yo ho ho! Yer not alone in askin', and kind strangers have explained: 1. [ELI5: Why does beta decay shoot the electron out of the atom instead of putting it to orbit and become a new element? ]( URL_6 ) ^(_5 comments_) 1. [ELI5: Beta decay ]( URL_2 ) ^(_5 comments_) 1. [ELI5:Beta decay, the missing electron ]( URL_3 ) ^(_4 comments_) 1. [ELI5: Beta decay ]( URL_0 ) ^(_3 comments_) 1. [ELI5: How does a neutron release an electron in beta decay? ]( URL_5 ) ^(_5 comments_) 1. [ELI5 Beta particle decay what exactly goes on when this happens? ]( URL_1 ) ^(_2 comments_) 1. [ELI5: what are the differences between Alpha, Beta, and Gamma decay ]( URL_4 ) ^(_4 comments_)"
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"https://www.reddit.com/r/explainlikeimfive/comments/1m9n2c/eli5_beta_decay/",
"https://www.reddit.com/r/explainlikeimfive/comments/5xn131/eli5_beta_particle_decay_what_exactly_goes_on/",
"https://www.reddit.com/r/explainlikeimfive/comments/soc2b/eli5_beta_decay/",
"https://www.reddit.com/r/explainlikeimfive/comments/689swz/eli5beta_decay_the_missing_electron/",
"https://www.reddit.com/r/explainlikeimfive/comments/30rh2r/eli5_what_are_the_differences_between_alpha_beta/",
"https://www.reddit.com/r/explainlikeimfive/comments/687sn3/eli5_how_does_a_neutron_release_an_electron_in/",
"https://www.reddit.com/r/explainlikeimfive/comments/1ny7cq/eli5_why_does_beta_decay_shoot_the_electron_out/"
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7qtyxh | Why is it easy to stay upright on a bike when moving, but difficult when stationary? | Repost | explainlikeimfive | {
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"text": [
"When moving, the wheels of the bike have angular momentum. Because of the conservation of angular momentum, the wheels want to stay in a particular direction unless a torque is applied. This assists in making the bike dynamically stable (As opposed to statically stable). When not moving, you aren't assisted by anything, so it can be difficult to balance the bike as it is an object with only two contact points with the ground."
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7qugi9 | If the boiling point of water is 100 degrees C/212 F, why do oceans, rivers, lakes etc not have to reach that temperature for clouds to form from them? | Repost | explainlikeimfive | {
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"Water evaporates all the time from the surface of any water body. Boiling is when the whole water body starts evaporating at once, not just from the surface.",
"100C = steam. Water can become water vapor at nearly any temperature (vapor != steam) otherwise a puddle would never dry up.",
"boiling point means that the average kinetic energy (thats temperature) is above the amount where material goes from liquid to gas. Some water will still be below that energy level, and even if the average isn't up there then some will still have enough energy to undergo that change. So some of it will evaporate naturally, without the whole liquid boiling (its also why your pot of water doesn't instantly disappear when it hits 100 degrees and boils)."
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7quzkb | How Snap Freezing works? | Repost | explainlikeimfive | {
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"For water to form ice, it's molecules have to arrange into a crystal lattice form. Being cold can make this possible, but if the water is pure & still, that may not be enough. It also needs a place for the crystals to start forming around. We call this a nucleation site. Water that is cooled below freezing temperature, but hasn't found a nucleation site, is called 'super cooled'. As soon as you give it a nucleation site, by adding something or even just shaking it up, then the ice will form rather quickly."
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7qy4vt | What is three phase power? | Repost | explainlikeimfive | {
"a_id": [
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"text": [
"I've searched tha seven seas fer an answer. Yer not alone in askin', and kind strangers have explained: 1. [ELI5 how three-phase power works ]( URL_2 ) ^(_7 comments_) 1. [ELI5: 3 Phase Power ]( URL_6 ) ^(_18 comments_) 1. [ELI5: 3 phase power. ]( URL_0 ) ^(_6 comments_) 1. [ELI5: What exactly are three-phase power systems? ]( URL_1 ) ^(_12 comments_) 1. [Fuckin' three-phase electric power -- how does it work? ]( URL_5 ) ^(_6 comments_) 1. [ELI5 Three-phase power ]( URL_4 ) ^(_8 comments_) 1. [ELI5: Explain 3-phase vs. Single Phase power ]( URL_3 ) ^(_7 comments_)"
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"https://www.reddit.com/r/explainlikeimfive/comments/qy1jt/eli5_3_phase_power/",
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"https://www.reddit.com/r/explainlikeimfive/comments/rh30r/eli5_how_threephase_power_works/",
"https://www.reddit.com/r/explainlikeimfive/comments/1jfywb/eli5_explain_3phase_vs_single_phase_power/",
"https://www.reddit.com/r/explainlikeimfive/comments/nlsx8/eli5_threephase_power/",
"https://www.reddit.com/r/explainlikeimfive/comments/le3nx/fuckin_threephase_electric_power_how_does_it_work/",
"https://www.reddit.com/r/explainlikeimfive/comments/4nzw1r/eli5_3_phase_power/"
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7r4ty6 | How can hot water freeze faster than cold water? | Repost | explainlikeimfive | {
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"Hot water loses heat at a faster rate than cold water but it doesn't freeze faster. Heat lose has an aspect of temperature difference in the equation (Q=mCp(T1-T2)) so the rate of heat loss is faster with a bigger temperature difference. Hot water from a tap does hold a lot more metal from the pipes (which is why you aren't supposed to cook with it). Metal ions in water provide a surface for the water to crystalize on, making the freezing process easier. Thats more related to where the hot water came from though than the fact that it was hot (at least not directly). EDIT: if you boil water and toss it into the air it will spread out and evaporate. once the mass of water is small, the rate at which it freezes goes up. A sitting pot of hot water will not freeze faster than a sitting pot of cold water."
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7r53vv | Elon Musk's belief that we are likely computer simulations | Repost | explainlikeimfive | {
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"Basically that as technology progresses, not only do things become more and more realistic, but that the users become more and more embedded in the experience (thing virtual reality and augmented reality). Elon suggests it's possible that humans became so advanced with hyper realistic virtual reality that we are not the users ourselves, but instead are the characters in a simulation and that the feeling of \"reality\" is incredibly well crafted. I don't think he *believes* this, though, but rather offers it as a theory to explore. Edit: apparently he does, in fact, believe it, as per a few correcting comments below",
"Elon Musk's belief that we are likely in a computer simulation requires just two assumptions. 1) \"Virtual reality\" indistinguishable from \"actual reality\" is possible. We know that human beings experience things through sensory inputs that can presumably be manipulated with advanced enough technology. 2) If there is only one base \"actual reality\" the number of \"virtual realities\" that can exist in the universe at any given time is much higher. If there are 20 hyper-realistic indistinguishable VRs and only 1 actual reality, we are 20x more likely to be in VR than actual reality. If you hold the above assumptions to be true, it's pretty hard to challenge the logic strictly on a philosophical or mathematical level.",
"We are at a point where we can run some pretty intense simulations and we've only been computing for a few decades - think where we'll be in a century or two. It's conceivable that we could create a simulated world filled with self-aware AIs who feel a very real existence. Assuming that's possible, what are the odds that we're the first to think of it? Going off on a tangent, there's an episode of Rick and Morty that explores this idea. Rick has a battery powered by a micro-universe inside it, filled with people generating power that he syphons to power his car. When the battery stops working, he goes inside this world and finds that a scientist in this world has created a new battery-universe, unaware that he is himself living within one.",
"I think this one would be easy enough to google and easily comprehend, I'll link a video that I watched and thought was really good in a sec. Edit: Link - URL_0",
"It's an interesting bit of speculative logic. Here are the points you need to buy into: 1. Technology will continue to improve. Note that it does not have to improve at the same rate as now. 2. A technological civilization can survive. 3. A technological civilization will remain curious 4. Self-aware A.I. is possible. If you buy into all four of those things, then at some point a technological civilization will be capable of running a large number of simulations including self-aware A.I. Now the question is: are we in the one true universe or are we in one of the many, many simulations? Considering that there is only one chance for this to be the real universe, it's much more likely that we are in one of the simulations. As an interesting aside, some people have theorized that the fuzzy nature of physics at the quantum level might indicate a kind of optimization similar to the kinds of optimizations we already make in our simulated MMO games.",
"For Elon Musk himself, he's probably on some sort of drugs, heard it, and thought it sounded cool. But let's consider the general argument. Let's say it's practical, in some universe, to simulate a reality using computers. (This can be done, it's just prohibitively expensive in our laws of physics.) So someone, for some reason, in that universe, decides to simulate a reality. And that reality is capable of creating people. If you're a person and you know that this happened and that's it, you might reasonably assign a 50% chance of you being in a simulation. Now, if one person can do this, probably many people can. So the odds are much higher than half that you're in a simulation. To take it further, in one of those simulations, someone builds a computer capable of simulating another reality. And similarly, once one person does it, many people can. So this multiplies the number of simulations by a large factor. But wait, we can apply the same process to the simulations inside the simulations! So now there's a stupendous number of simulated universes. What are the odds that yours is the one on top? Very low indeed. There are some problems with this, but that's the basic idea.",
"Yeah but have you gotten to play Second Second Life? I know a pretty good paper salesman there."
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7r6s6o | Stainless Steel is hard. Meat is soft. You take a stainless steel knife that is very sharp and start to cut meat and the knife gets blunt very fast. Why? How can something so soft destroy the sharpness of stainless steel or other metals? | Repost | explainlikeimfive | {
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"I sold cutco knives for a brief period of time so I actually know the answer to this. The answer is that very little food actually dulls your knife. It's usually your cutting board. Wood, plastic, stone, ceramic. All of these dull your knife edge very quickly. The \"trick\" to cutco knives is that the actually cutting part never makes contact with the cutting board.",
"Part of it is that the ultra-thin edge gets *folded over,* rather than actually blunted. Even a soft (but dense) material can do that."
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7r9cz9 | How can we "hear thoughts in our heads when we can't physically hear them ears? | Repost | explainlikeimfive | {
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"text": [
"One of the nice features of the brain is it's ability to simulate things, benefit of the frontal cortex. This helps us do a lot of things like not touch the stove (that would hurt, my skin would sting) hang out in public bathrooms (smells like pee, I don't like that), and hear our thoughts before we voice them. It's been suggested that this helps us organize our thoughts, similar to talking out loud. There's a popular technique for problem solving called the rubber ducky method, where you explain your thoughts to an inanimate object like a rubber duck out loud to better think through a problem. It's like your friend asking you for help on a physics problem and explaining it, only to get it before he gives you the chance to try. Source: took psychology last semester"
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7ra2bh | Why are cryptos primarily(always?) mined using the GPU? | This specific question came to mind, but it also solidified the thought in my mind that I don't really understand how a CPU/GPU works and its primary function. Hopefully I can give some more context through some other questions I have, in turn giving more insight to where this question is stemming from. So, why are cryptos primarily mined using the GPU, but what does that say about the CPU; why is a GPU more efficient at these computations? What specifically is GPU designed for(Image processing?)? Image processing, but what exactly does that process look like? What steps are taken on the path of processing an image? Both virtual steps and physical steps. How does that process correlate to coin mining such that it is more efficient to mine via the GPU? Does it have to do with registers? Is a register simply a different piece of memory? just closer(easier to access) than RAM? What path would the computation take if the CPU were processing it vs if the GPU were processing it? | Repost | explainlikeimfive | {
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"TLDR: Cpus run your computer, and thus have to be able to do a lot of things well at the cost of speed. GPUs are mostly just process graphics, which is mostly a monotone process. As such they are built to do few things incredibly fast. CPU are masters of general logic. They can do a lot of different things very well, and as such are great at running your computer and general purpose computing. GPU's are designed to do one thing very very well: repeated calculation. Their intended purpose is processing graphics which involves a whole lot of doing the exact same calculation over and over and over. Most of graphic processing is just built on linear algebra and a whole lot of matrix multiplication. They are thus optimized to be able to calculate a lot of similar things in parallel using multiple cores. Because cryptomining is just running a hashing function again, and again, and again, until you find an answer GPUs are a prime candidate (aside from single purpose CPUs) for mining. Their entire purpose is to calculate a lot of things fast."
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7rbtdo | the 4th and 5th dimension | Repost | explainlikeimfive | {
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"Imagine a new type of people that only exist on a piece of paper in two dimensions. They can go left and right on the paper and up an down, but they cannot go past the paper. They only exist in 2 dimensions: up/down and left/right. Now if you were to show them a ball, they wouldn't be able to even fathom a ball. At best, they would be able to see a rapid series of circles coming at them getting larger and then smaller as the ball goes past. Now you exist in 3 dimensions, but the 4th and 5th would be similar to you as the ball is to a flatlander. We can explain the dimensions with math, but we can't experience them. Our brains are simply designed to operate in 3 dimensions and not more. Additionally, some people refer to time as a 4th dimension, but since I assume you actually meant spatial dimensions, so that is what I explained it as.",
"URL_0 Carl Sagan is really good at explaining things.",
"Imagine a line. A line is one dimension. Now how do we make this a square? We tilt it up on its side while leaving the first one behind and finish the other two lines, now we have ourselves a square. How do we make a square into a cube? We turn it on its side, finish the other 5 lines. Now we're in three dimensions and have a cube. How do we get to four dimensions, a hypercube? Well, when we look at a line and a square, the square can be gotten by \"popping\" the line sideways into two dimensions, and the cube from the square can be gotten by \"popping\" the square up and into three dimensions. So, it makes sense, for us to get to the fourth dimension we need to pop the square... in what direction? This is the constraint of our third-dimensional thinking. In what direction do we pop out? There are two ways of thinking about this. One is that there is that there's some unseen direction (that for the most part, I visualize as diagonal when needed) and we simply turn the cube on its side in four dimensions and connect the other 20 lines, creating a hypercube. Continuing this process for a hypercube, we get our fifth-dimensional cube or penteract. The other is that the fourth dimension is time. Suppose there was a world working in two dimensions on an infinitely wide plain and you pass a sphere through it, from their perspective, they see a circle appear, get wider, smaller and eventually disappear. Now imagine the sheet is blank and you pass through an extremely complicated spiral thing, and from the 2d perspective, it's playing like an animation, going through a universe. Every instance is in this 3d shape but the 2d people can never experience it. This 3d object shifting shape as it passes through becomes time. Now imagine the same for a four-dimensional object going through our space, we see a collection of 3d space moving around, but 'time' is just the shifting of this four-dimensional object. Puts you into perspective, doesn't it? All that being said, I'm no expert, but that's my take on it all. And as has been mentioned, we can explain these dimensions mathematically but our minds can't experience them."
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7rcgxi | How does everyone have a different voice? | Repost | explainlikeimfive | {
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"text": [
"The shape of everyone’s vocal chords are different. This effects how frequencies are produced. Every trained singer can sing the same note, but we can’t produce a pure sine wave that is exactly one frequency. Instead we produce a note that has a specific base frequency and then based on the shape of our vocal chords and some other factors we also produce additional frequencies at varying levels. This gives us our unique voice and is also the concept that makes a trumpet sound different from a piano or a flute. Google frequency graphs of ‘overtones’ for more information."
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7rdqva | What is fantasy football and how does it work? | Repost | explainlikeimfive | {
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"text": [
"In a nutshell, people get together and make up imaginary \"teams\" composed of actual NFL players. There's usually some sort of imaginary budget, a mock draft to choose players, etc. Statistics for those players serve as the basis for scoring how well your players are doing each week. Typically people who get together to form a fantasy league charge a fee which goes towards some sort of prize for the winner after a season. All in all it's just a fun way (for some) to stay interested and engaged in the sport as a whole."
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7rfkht | - How can I regulate my entire body's temperature by sticking my foot outside of my bedsheets? | Repost | explainlikeimfive | {
"a_id": [
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"text": [
"It's like a heat sink on a cpu. Blood there exposed to cooler air cools your blood. This cooler blood circulates in your bloodstream cooling your body. New warm blood pumps into your foot cooling it a little bit more"
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7rgtdj | Why do our joints and bones hurt when the wearther is changing? | Repost | explainlikeimfive | {
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"text": [
"Changes in weather are accompanied, and in fact usually preceded, by changes in atmospheric pressure. Changes in atmospheric pressure affect the fluid pressure in your joints. Changes in fluid pressure in your joints hurts."
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7rha9b | when you're ill, why do you feel the worst in the morning and better throughout the day? | Repost | explainlikeimfive | {
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"text": [
"Being horizontal and immobile allows a lot of buildup of goop, so for instance the back of your sinuses and your throat get coated in an extra thick layer of old dry mucus, making any cough or laryngitis worse, as well as keeping your lymph nodes from draining well, causing additional swelling. You just fasted for 8 hours, you're dehydrated and hungry. Most symptoms of illness are actually things your body is doing to itself to keep the illness contained. When you're asleep your body does them harder because you aren't doing anything. Your immune system responds to you doing things or not and cranks up or down your symptoms to match; for instance you may notice that if you start working hard on something physically intensive you stop producing as much mucus, you stop feeling as achy, and lymph node swelling goes down as your immune system slows down, but other symptoms like headaches get worse because you're not containing the illness as well anymore.",
"Maybe because you're at your most dehydrated and malnourished when you wake up?"
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7rjrif | how do we know the calculation of pi number is correct? | Repost | explainlikeimfive | {
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"text": [
"Most approached for calculating pi are series expansions that have mathematical proofs of their equivalence to pi. [This great Wolfram Alpha page]( URL_0 ) explains the most common formulas and cites their discoverers."
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7rlx3o | is the concept of light speed defined by light itself, or does light just want to go infinitely fast but physics puts a cap on it? | Repost | explainlikeimfive | {
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"text": [
"As far as we know, it's the second one. Particles with no mass travel as fast as physics allows anything to travel. Since photons are the massless particles that we encounter most often, we first encountered that maximum speed by observing light and we called that speed \"the speed of light\".",
"Light is fast, way faster than most people can even imagine, but thankfully our measurements are very precise as well, so we are able to measure it very accurately (First done by Fizeau and Focault in 1830ish, not like /u/ganganinja claims by sending lasers to the moon, we do that to measure how far the moon is away, knowing how fast light is and then measuring the time). Light, sadly, is not infinitely fast, it is actually very, very, very slow compared to the size of the universe, even the closese star is lightyears away form us, meaning that the light you see when looking up at the sky and seeing all those small little bright spots has taken millenia (and often way, way, way, way, way, and i mean like way way way, longer than just a few millenia, wich is basically no time, to be honest), to get from the star that emitted it to us here on earth. I would also like to add that in fact these days we dont measure the speed of light at all, in the 1980s we just agreed on the speed of light as a certain number (exactly 299,792,458 metres per second) and are now using that number as the basic measurement for everything (so if you know how long a metre is you no longer go to baris and look at that stick napoleon made and about wich he said \"this is a metre, and any metre on earth is defined by beeing exactly as long as this stick\", you instead take the distance for wich a beam of light needs exactly 1/299,792,458 seconds to travel it)",
"Watering it down, a lot, light is a wibble in the em field. Sound moves at different speeds through air, or helium, or steel essentially because of atoms knocking into each other. So basically energy take time to transfer through the material. Even light! Because its just a wibble in the EM field. If you were to shine a light next to a steel beam while passing electric current through the beam, the light would arrive *just* ahead of the electric current. The energy took longer to travel through steel than free space. Suppose you wanted to travel faster than sound, what happens? You move faster through the air than the air can transfer the energy of the sound you make. It stacks up and you get a boom, all the sound at once. What happens when you toss a light speed particle at steel(which it should travel slower through, electric current is a wibble in the EM field too), what happens? Well, again really watered down, the energy stacks up and you the excess energy gets released as [Cherenkov radiation]( URL_0 ). A light boom! Ok so TLDR whats this all mean? Light can travel slower through a material. But in free space, a vacuum, it travels as fast as energy can be transferred through the EM field. You can't travel faster than C because youd outrun the fields holding you together."
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7rmj2s | How do microwaves not heat up plastic and ceramic dishes? | Repost | explainlikeimfive | {
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"text": [
"Microwaves excite water molecules and make them vibrate, there are no water molecules in plastic or ceramic.",
"Those substances are transparent to light at microwave frequencies. It's like how light can go through a window and warm up the cat.",
"It all has to do with polarity of the molecules. Microwaves work by emitting microwaves in alternating directions which causes the polar molecule to move slightly. Since this happens so fast the molecules look like they are vibrating and this vibration heats up the molecule. This is why a polar molecule like water will heat up. Molecules that are not polar like plastic, ceramic, oil, etc don't move or vibrate which means they won't heat up. You can test this out by putting a small cup of olive oil in the microwave. It isn't going to heat up and you will be amazed."
],
"score": [
5,
3,
3
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|
7rmup7 | why is it that cameras cannot take a clear picture of an LCD screen? | Repost | explainlikeimfive | {
"a_id": [
"dsy3r9k"
],
"text": [
"Monitors and TVs typically have a set refresh rate - 50Hz and 60Hz are fairly common. This means that the screen is redrawn around 50 or 60 times a second. To the human eye, this looks smooth - it's fast enough to be almost unnoticeable. Cameras, though operate differently from our eyes. If the frame rate of the camera matches the refresh rate of the screen you're looking at, it'll probably look fine. Usually, this isn't the case. The camera then could capture a partly drawn screen as one of it's frames, and then capture a different part of the screen in the next frame, etc. Net result: it looks like it flickers (or you see moving black bars), since it does this very quickly. The black bars are a slightly different story from the flickering - the issue there is called aliasing. It's the same reason why if you film a wheel moving at the right speed, it can look like it's spinning backwards. If you think of video cameras as just taking a lot of pictures really fast, the way we perceive motion in a video is that you assume things move the smallest amount possible. So if a wheel has 8 spokes (evenly spaced, 360/8 = 45 degree separation) and rotates 35 degrees between frames, you'll probably think it took the shortest possible rotation - 10 degrees in the opposite direction (this breaks down if the spokes are distinguishable). The black bars you make see on some cameras are the same effect - the camera captures snapshots at different points in time that make it look like the bars move in a way vastly different from the actual scanning of the screen."
],
"score": [
9
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"text_urls": [
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} | [
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|
7rt5sp | What's the practical application of imaginary numbers? | Repost | explainlikeimfive | {
"a_id": [
"dszezz8"
],
"text": [
"They're used in a lot of math that has real world applications since they can be used to denote the x and y axes of a sinusoidal function. For example the function F = cos(theta) + i sin(theta) has tons of practical applications in electric circuits, mechanism analysis, and in a fluid analysis technique called potential flow. The details of these applications are quite a bit beyond ELI5 though. Just know that the equation I posted above is super useful in many fields."
],
"score": [
3
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|
7ru2k4 | if human skin cells reproduce and you essentially have different skin than you did 5 years ago, why do scars never disappear? | Repost | explainlikeimfive | {
"a_id": [
"dszl8si"
],
"text": [
"From what I understand scars are made of collagen fibres, and when the layers of skin move from the deeper layers to the surface to eventually be shed it simply moves around this different structure of collagen fibres (the scar) instead of eventually shedding the scar as well"
],
"score": [
4
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"text_urls": [
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|
7ru9jz | What is the source of heat for the Earths core? | Repost | explainlikeimfive | {
"a_id": [
"dszmckf",
"dszniyv"
],
"text": [
"> What is the source of heat for the Earths core? A small portion is residual heat from the initial collapse of material into the gravity well of Earth, but the majority at this point is from radioactive decay of heavy elements in the core.",
"The majority comes from radioactive decay. There are various elements in the core which are not stable; slowly, over time, they decay into lighter, more stable elements. This doesn't produce much heat per volume, but that heat has nowhere to go; the crust makes for a very effective \"blanket\" to keep that heat inside. That, combined with the sheer size of the planet, means that the core is hot enough to be molten (though the core itself is solid due to pressure). Other sources of heat include the residual heat from Earth's formation and tidal heating from the moon. For tidal heating, note that the moon doesn't pull all parts of Earth equally: the side closest to the moon feels the moon's gravity slightly stronger than the side farthest away. This leads to Earth squishing a bit (and water sloshing around a bit--tides!), which means some friction internal to the planet. Some celestial bodies feel this effect so strongly that it is sufficient to melt their core on its own; Jupiter's moon Io is a notable case of this. The relative size, distance, and mass of the moon means that it wouldn't be enough to keep Earth's mantle molten on its own."
],
"score": [
6,
5
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