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mlcnj8 | Why is it that when you cook an egg in different ways, the taste outcome becomes different? | Take seasoning out of the picture, why does scrambled egg taste different than boiled or omelette? Although it's the same egg white and yolk? | Other | explainlikeimfive | {
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"That's not just true for eggs, that's true for literally all foods. Boiled vegetables don't taste the same as fried vegetables. Different cooking methods have different effects on the chemistry of food and that gives it different textures and flavours. It's not something specific to eggs"
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mlcvga | why psychopath criminals are sadistic, narcissist and cold blooded people if they literally can't feel ANY emotion? | Biology | explainlikeimfive | {
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"That's an incomplete and simplified definition of psychopathy. The primary emotion they're missing is empathy. There are plenty of benevolent psychopaths who don't feel normal emotions but they have no desire to harm anyone. They still feel things like excitement, anger, and amusement. They have trouble with the complicated emotions."
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mld2mm | If you ate bad food, how does your body decide if it's vomit or diarrhea? | Biology | explainlikeimfive | {
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"Largely, time from when you ate it though *both* are common. If your system recognizes the poison before it enters your intestine, you get vomiting. After, you get diarrhea. Vomiting can start within the hour, often 30 minutes to 8 hours. Diarrhea can start within 12 to 24 hours.",
"It's usually a question of: HOW BAD IS BAD? Once something passes through the stomach down into the intestines (\\~6-8hrs after eating) it doesn't come back up. If the food is Very Bad, i.e. it's already got a few million to billion bacteria on it, your body can recognize that before it exits the stomach, and send it back up. If it's Only Kind of Bad, i.e. a few hundreds to thousands of bacteria on it, it'll usually get past the stomach. If any of those bugs survived the stomach, they can start reproducing again once they're down in your GI tract, and that's when your body sounds the alarm to flush things out—once the number of bacteria gets high enough that your body decides it's Very Bad.",
"It can depend on where the toxins are from the bacteria causing the food poisoning. Bacteria produced these toxins through a variety of normal biological actions such as multiplying. If the toxins are in the food, your body will most likely pick these up in your stomach and this will cause you to vomit, as this is the quickest route out. If the bacteria produce toxins in your body, it'll most likely happen in your intestine as this is a preferable environment to your stomach. Here they will produce toxins and your body will try to take the quickest route out, the back door. And sometimes, just for kicks, your body will decide to empty everything out of both ends, just to be sure!",
"LOL. This brings up a memory I forgot about. I was taking training sessions for a week out of town for a large bank. They were putting us up in a hotel for the week & it was Friday, we were finally about to go home. For lunch that day I ate Arby's Roast Beef sandwhich(s?). Love that shit. If it wasn't 30 minutes, then within the hour I was pretty much continuous vomiting, it was very obvious I got food poisoning from Arby's. At first I was so embarrassed because I was getting so sick while I was supposed to be learning how to be a teller, but after awhile I didn't even care anymore. I was a 30+M and these lady's were helping me walk to the bathroom 'cause I could barely stand, bringing me decarbonated sprite/blankets. I was fetal most of the time, just getting up to puke in the trash can they gave me. Class ended, everyone started their drive home...I was starting to wonder what I was going to do, I really wanted to go home, but I was about 2 hours from the house. Luckily the bank downstairs was open late 'cause it was a Friday so I had some extra time to recover from all the puking. I was ready to get a hotel if I needed it, but I was finally able to drive home. story over.",
"TMI below for the weak of stomach: One of the worst moments of my life was when I was shitting my brains out on the toilet and suddenly I thought to myself, \"oh my god, I have to vomit too.\" I leaned over the bath tub and chucked. IT WAS AWFUL! I don't even remember what caused the food poisoning but it was so gnarley. & #x200B; Fortunately after that moment, it was out of my system but I didn't have an appetite for a day and a half.",
"Vomit comes from your stomach if your body wants it out very soon after eating. Otherwise, it makes it to your small intestines and colon and if it isn't processed properly you can end up with diarrhea."
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mld7pi | Why can't we give protons to something to give it a positive charge instead of removing electrons? | In physics class today I learnt about charges and how to make an object charged. But my teacher said when we want to give a positive charge to an object we can't give protons to it, only remove electrons from it to make number of protons more. Why is that the case? | Physics | explainlikeimfive | {
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"Protons r big and removing them from one atom would be crazy energy, this is how nukes work",
"Protons bond *extremely* strongly in the nucleus of the atom once they are in contact, and generate an electric field that repulses other protons until they get close enough for the nuclear force to overcome it. So it's extremely hard to break protons out of an atom (you need basically a particle accelerator or sustained nuclear fission) and even when you can, it's very difficult to capture the protons, channel them towards another atom, and get them close enough to bind to the protons and neutrons already there. Electrons exist in a cloud around the nucleus, and are much easier to separate from the nucleus.",
"On top of these explanations, your physics teacher is there to teach you. If they say something that you don't understand, ask. Your teacher is much more likely to give you a better answer than asking random people on the internet. Seriously, folks asking the internet instead of an expert is a huge problem right now."
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mldrvo | the Federal Reserve System | Economics | explainlikeimfive | {
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"Federal Reserve banks are not owned by private banks. The FRS is a self-financing government corporation. Its Board of Governors is appointed by the President. The Federal Reserve Bank Board of Governors then chooses members of the Board of Directors for each regional bank."
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mldw50 | When tires wear down, where does it go? | If we are all driving around on tires and the tread wears down, where does the tread go? It doesn't evaporate or change state like liquid to gas? That would make me think we would see piles of tire debris on the side of the freeways or humps in the road where tires are constantly driving. If you think about all the tires sold in the world, and all the tread worn off of them- where did that tread go? | Other | explainlikeimfive | {
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"A little rubber becomes chemically incorporated into asphalt roads, because asphalt and rubber both are made of petroleum oils. But the vast majority wears off as small particles that are rinsed off the road by rain, or blown off by wind, ending up in the soil, on plants, and in lakes, rivers and streams.",
"Matter never created or destroyed grasshopper! In this case teeny tiny microscopic particles break off burn off from friction. It’s all still out there. Stuff Runs off enters the watershed. Water connects everything. It’s kinda amazing",
"It becomes micro plastic for the environment along the road, for all the cute critters to ingest and move up the food chain.",
"You ever see the tracks on roads where the tires have made permanent marks? A lot of it there. Some gets washed away in rain. It doesn't evaporate"
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mle4ge | How do statisticians apply a small sample group to a whole population? | Like how do these people gather enough information to account for the whole population for, for example, party ratings near times of election? How do you make sure these statistics are accurate enough? | Mathematics | explainlikeimfive | {
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"A sample isn't perfectly representative of the whole. The only thing that's perfectly representative is the whole itself. But we can't do that so we take a sample, and with that comes probabilities that the results are representative. So when you see statistics, you should also see: * Confidence level. This will usually be like 95%, but you can see it 80-99%. This is the percentage confidence that the results match the whole population, that if you keep surveying over and over you'd get the same result. * Confidence interval: This is the +-3% or so that you see. So if they say 70% of people agree on something at +-3%, that means the true number is somewhere between 67-73%. This is also known as the \"margin of error.\" * P value. You have your hypothesis where you can be right, and then you have the null hypothesis which means your results are meaningless, that you could have achieved these results even with your hypothesis being absolutely wrong. This will be represented by a p-value. Usually, .05 is acceptable (a 1 in 20 chance you're completely wrong). But this can be misleading because there is a thing called p hacking, where you fudge the numbers to artificially drive up the p-value. So don't take p= < .05 to mean the results are true. All of this together combines to give you general probabilities that your sample is representative. The more you want to drive up the confidence level and lower the confidence interval, the more of a sample you need. For example, a representative sample for our population at 95% +-3% is 1068. If you really want to lower the odds you're wrong you could do 99% +-1%, but you need a sample size of 16,641. Conversely, if you just want to get a number you like out in the media and hope nobody notices what you're doing, you could do 80% +-6% and you'd only need to sample 114 people. So your \"80% of people like X\" really means as few as 74% do, and there's a 1 in 5 chance your sample is not representative, that you'd get different results every time you did it, so nobody should trust the results. But as I said, you rely on the fact that most people will just trust the number and not dig too deeply. I always say the best class anyone can take in college regardless of the degree is statistics. You will learn to spot many lies and end incorrect assumptions. For example, \"Ooh, this car maker has a long warranty, so they must be built well.\" Nope. They take the expected failure rate and cost of repairs and run that through statistics. A long warranty could mean the car is crap, but they've allocated more money for warranty repairs. \"We don't want to spend $$$$$ to increase quality, but we could spend $$$ on extra warranty service and make more profit. Besides, warranty brings them into the dealer where we can try to sell them more stuff.\""
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mlessy | Why can we tell just by listening that someone is smiling while talking or singing? | Other | explainlikeimfive | {
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"Over time your mind becomes accustomed to the slight variation in acoustics a familiar spoken language has when said through a smile. The research study I read about this put it as \"Prototypical ideals,\" but that means pretty much the same thing. The cues are so strong that the slightly different alterations of the sound stemming from different levels of smiles can also be picked up, much of this subconscious; you can tell when someone is slightly smiling, fully, suppressing one, etc. Basically, they sound different and the human brain is very good at picking stuff like that up even if you don't consciously notice it. Edit: I pulled up the [study]( URL_0 ) for anyone curious. IMHO, it's pretty cool we can even do this, the brain is amazing."
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mlfdqc | Why are things that are going to fall or move, drawn different in cartoons/anime? | For example : If there is a mountain climbing scene in a cartoon/anime, and a character grabs a rock that's going to fall, it's most likely to be drawn in a different shade with less details on it. | Other | explainlikeimfive | {
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"Thats an artifact of cell animation. Basically the different parts of the scene are drawn on different sheets of a clear film, with the background sheet behind everything. This means when animators had to hand draw something that was going to move, they only had to draw that item instead of the entire scene. So they could draw a background in detail because they only drew it once. If something was going to move they may have to draw it dozens or hundreds of times. Edit: To add, this doesn't occur in modern cartoons because they are computer generated rather than hand drawn. So these considerations no longer apply unless the show creators intentionally add it for stylism.",
"The backgrounds of traditional animation are generally more detailed because, like you implied, they don't have to move. The animators make a single image look as good as they can. But for the moving parts, they have to be simpler to look consistent from frame to frame. Have you ever seen an animation style that's basically all paintings? Each frame is strikingly different from all the others, and it causes a flashing or shimmering effect because the brush strokes are so varied. But for mostly flat colors, that effect is very much reduced in regular cartoons."
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mlfgyv | ;What’s the detriment to “highly processed” foods? | Other | explainlikeimfive | {
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"\\*In general\\*, the more you process foods the more additives get in there...salt, sugar, dyes, artificial flavours, etc. You also tend to lose water, fiber, and bacteria (depending on the food), which don't show as nutrients but can still be good for you. None of those additives are necessarily bad on their own but the more you process the farther the food's nutriotional (and non-nutritional) profile drifts from where is started. That's \\*not\\* generally true for food oil. Most of them are just squeezed out of the source plant, through a filter, and into a bottle. I'm not aware of any meaningful processing difference between, say, canola and olive oil. Hydrogenated oils (e.g. Crisco or margerine) are a different case, but just straight veggie oils? Oil is oil is oil, from a processing standpoint. There's other reasons you might like olive (it's relatively high in unsaturated fats, which can be \"good\") but that's nothing to do with processing."
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mlfmem | How in the world do rich people file their taxes in such a way to avoid paying absolutely anything at all, and how could a normal person do the same? | Economics | explainlikeimfive | {
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"Having a lot of money doesn’t necessarily mean they have a large earned income for the year. I could own 100,000 shares of Tesla and if the stock rose $100 for the year, I made $10 million. My net worth would reflect that, but if I don’t sell any of those shares during the year, I don’t have to pay any taxes on them. Only when I sell do I pay taxes. The same could be said for real estate. I own 5 houses and their value doubles in a year. My net worth rises, but again, I don’t pay taxes unless I sell the houses. (I know property taxes are still a thing, but I’m strictly talking income tax). Another thing that can be done is to receive write offs for charitable donations. Donate $100,000 to a qualified charity and that is $100,000 less you have to pay taxes on. You can also carry forward losses if you lost money in the stock market in previous years. Those losses can be deducted from any gains you made and sold this year. So there are some CEOs who get a majority of their salary in the form of stock in the company and may only take home $100,000 in cash paychecks a year despite gaining $1,000,000 in shares of stock.",
"Taxes are focused on money income. There are other kinds of income that aren't taxed. The IRS isn't interested in the \"income\" I get from my garden even though my produce has a cash value. The IRS also isn't interested in things like your house or a business going up in value (until you sell). Rich people have enough resources that they can strategize their income in ways that people living paycheck to paycheck cannot. They maximize income that isn't taxed until they want to turn parts of it into money and when they do that they plan to minimize their taxes with every available strategy to reduce their taxes.",
"They can hire people knowledgeable and trained in tax law and regulation. They also have assets in quantities that allow them to use certain programs and processes in a way that will actually have a benefit. These include many deductions. Most people don't do itemized deductions because the amount they can deduct will be less than the amount allowed under the Federal standard deduction. Rich people don't avoid paying taxes at all as much as they utilize existing rules to reduce their legal tax burden down to the absolute minimum required (you likely do the same with the standard deduction). When media reports they \"avoided $X in taxes\" it is refereing to how much less they paid than the base rate for that income bracket, not that they didn't pay what they are legally required. And there are some years where they may experience losses in assets that overcome their annual income, which can allow them to deduct their entire income (owing nothing), but this happens when they have already lost a lot. (normally)",
"I can answer. I don't consider myself \"rich\" but I do make and have a lot of money compared to the average income in the US. The first and most important distinction to understand is the difference between earned income and asset appreciation or business cash flow. Most people pay taxes on earned income, which would be your salary, wages, tips, etc. Everything that shows up on your W-2 from your employer. Wealthy people don't earn money this way. So they don't pay the same taxes you pay. Wealthy people buy rental properties, invest in stocks, and operate businesses. Capital gains tax rates are different than earned income tax rates and that amounts to a large difference in total taxes paid. Now for business cash flow. People pay taxes on their income and use whatever is leftover to live on. Businesses pay all their expenses pre-tax, and then pay taxes on what's leftover (profit). So if I own a company that earns $10M a year in revenue, but has $10M a year in expenses, then I pay zero tax because I had not profits. The trick is to wrap things into your business to avoid paying tax on them. For example, my wife's car has a company logo painted on it so the IRS allows me to call her vehicle a marketing expense. I pay for her car with pre-tax dollars whereas most people pay they car payments with whatever money is left over after taxes are paid. I operate a business out of my home so portions of my mortgage and utilities are written off as business expenses and that reduces my taxable income. Wealthy people spend a lot of time and energy structuring their finances so that they're paying expenses with pre-tax dollars and reducing their taxable income. Another strategy is when you own multiple businesses you can offset income with losses in other areas. So if I have one business that makes $10M in profit this time (meaning after all expense are paid), and I have another business that broke even but has room for growth, I can spend $10M on that business purchasing new equipment and materials and that offsets the profits from the other business. I'm now growing my business and making money hand over fist but I'm not paying taxes on it because I'm investing that cash back into my businesses, increasing their worth and mine as a result. You may look at this and think it's totally unfair. I want to point out that your frame of reference is likely too narrow. When people are up in arms at folks like Jeff Bezos' Amazon not paying federal taxes, they're being intentionally narrow-focused. Everybody that pays employees, has to pay FICA or payroll tax of 6%. The average Amazon employee makes $35k, and there are 575,700 Amazon employees. 575,700 \\* $35k \\* 6% = $1.2B in taxes just on the cost of their labor. And they paid another[$300M]( URL_0 ) on state, local, property, and unemployment insurance too. They pay more taxes than you or anybody you've ever known combined. I don't have anywhere near that kind of money, but I can tell you that legally funneling certain expenses through a business saves me lots of tax dollars each year. I don't have a fancy tax attorney or an accountant on payroll. I do it myself.",
"There are of course many instances of fraud, but the majority of wealthy people take advantages of investment laws to avoid paying as much tax as would otherwise be payable. For example, if you have investments in a money losing venture or bad stocks you can claim capital losses when you sell them. Capital losses can be carried forward for many years and offset capital gains you may have made on other investment. And in my country 50% of capital gains aren't taxed at all. So it's quite easy to lessen your tax burden if you have good accountants and financial planners to help you.",
"They don't. First of all the notion that rich people don't pay anything in taxes is bogus to begin with. Let's be clear on the ask here. State and local taxes, Federal Income tax etc. There is a huge difference in using the law as it's written to allow yourself a lower tax rate, as opposed to doing an illegal activity like tax fraud etc.. The short answer is that they find specialized attorney's and tax professionals to take advantage of the tax laws. A normal person doesn't have the business write offs and tax shelters on income that come from owning a business (even if that business is largely nothing more than a tax write off itself).",
"This is a very loaded question. You're coming in making statements and assuming the rich people do a certain way and want an explanation as you think you're right"
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mlfzex | How are pirated movies recorded at such a high quality? | Technology | explainlikeimfive | {
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"Pirated movies are the same resolution as theater movies. Pirates aren't sitting in the back row with a camcorder. Most of these are data processed from the same data shown on the screen.",
"For early releases, High quality pirated movies are generally from screener versions of the movie (or any other pre-release version), Studios do ALOT of screeners and copies for celebs, friends, reviewers, critics, journalists, industry people, and awards shows. That is the studio sends out physical or digital copies of the movie for people to watch at home and during this process the pirate gets access to said movie, and makes a copy. Of course after this, once the movie is out in the public hands in physical form or on cable/streaming/etc., they have access to the general consumer version, and its trivial to make an exact copy. \"cam\" movies, which are low quality, generally are shot with a camcorder in the movie theater, and if they're lucky, they have a direct audio feed from the movie (yes that means someone at the theater is in on it), if not they just record the audio in the theater which is often pretty poor quality. Many cam recordings are done in theaters in Asia.",
"The other technique that you often see is 'Telecine', generally indicated in the title of the file as 'TS'. This technique uses a special camera and device to essentially scan the analog film strip to digital by photographing each individual frame. This can produce very high quality digital files depending on who's doing it and the quality of their equipment but a pure digital rip these days is still generally better. Fun side note: This is why so much stuff from before the '90s can be 'remastered' to look amazing today while there is a dark zone of early '90s - mid 2000's of stuff that's pretty bad. The earlier stuff can be up-scaled right off the original film, whereas early digital stuff was not shot in sufficiently high digital resolution to look good on today's AV equipment even though they were perfectly acceptable for a typical CRT TV of the time. While it's not impossible to upscale a low resolution digital video file, it's very hard and time consuming, usually involving techniques such as machine learning",
"There is no inherent reason why 'pirated' movies would be any lower quality than non pirated. You can buy a blu-ray disk, transfer the file to your computer and then upload that file.",
"In addition to what the others are posting, if Movie X has a July 1 release date, you can be fairly certain that it already has a BluRay release date sometime around October(ish). Those discs need to be mass produced (probably in some third-world factory), shipped globally, and stocked on retail shelves. That takes lots of time, so they begin manufacturing them sometime around.... July 1 or so. One of the discs accidentally doesn’t make it into the case, slips inside a pocket, and BAM, blue ray quality movie is now in the hands of a pirate.",
"Prescreening, releases for “awards considerations” very few is someone sitting in a movie theater with a bucket of popcorn and a camera hiding.",
"Simplest explanation: if you can see it, you can record it. Similarly: if you can hear it, you can record it. Some early-release movies (likely screeners, used by award companies to preview a movie before it hits theaters) have special software on the DVD that supposedly prevents certain recording software from being run. But capture cards throw all that work down the drain. All you need is a second computer hooked up to the player, and the DVD doesn't know anything's amiss. There may be some initial sound sync issues (if the pirate is a newbie), but usually not more than 200/300 milliseconds. So the second computer records, upload the file to the pirate bay, and Bob's your proverbial uncle."
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mlgowf | how are bodies identified with dental records? | Biology | explainlikeimfive | {
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"The medical examiner will take X-rays of the deceased mouth. These X-rays are compared to X-rays within the person’s medical records. There’s enough variability in tooth shape, size, and precious dental work for a match to be probable.",
"They basically have to have a good guess of who they are. Then they can do X rays and compare the teeth to the records of the person's dentist. So if you haven't been to a dentist ever, they can't match you up.",
"Dentists are always xraying and taking those prints of bite patterns, forensics can request acess",
"The shape and pattern of your teeth, as well as any dental work (fillings, crowns, etc.), are unique to you. Skulls/teeth survive almost all decomposition and death processes, so if you can find it and compare the teeth to the dental records (X-rays, mostly) then you can match them like fingerprints."
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mlhr6m | Why social credit score system is such a bad idea? | Other | explainlikeimfive | {
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"Who decides what’s “good” and “bad”? The government? Big business? The mob mentality? Do you truly trust any of those entities to have any semblance of fairness and impartial behavior, or will they just ostracize and destroy whoever they happen to dislike that morning? It’s the stuff of totalitarian dystopias, not a free society.",
"It destroys the concept of individuality, personal autonomy, and freedom. You are giving over to the government (or whatever business running it) the authority to not only craft laws forbidding extreme behavior but to micromanage all behavior that a person does. Anyone who does anything against orthodoxy will stop being able to travel, get jobs, get medical treatment, buy food, etc. It is totalitarian and abhorrent.",
"So... on one hand, a social credit score can be good - it can encourage behaviors that benefit society... but it depends entirely on the society that implements it and what its trying to encourage: as _could_ happen in the case of China's implementation is it gets co-opted to encourage behaviors that benefit particular demographics i.e. the state (and not its people... despite what the state claims). For example: if one were to altruistically reward \"being kind to people no matter who they are\" vs. the CCP's \"..except if they're Uyghurs\". \"Engage in spirited political discourse\" vs. \".. except if its critical of the state.\"",
"Look into the manipulation and review bombing that happens on Yelp, and imagine that happening to you. As with many systems, the idea isn't that bad but humans will make it bad.",
"Once a system like that is implemented it has a very high potential to slowly get changed into a tool for maintaining control and power by adding or changing the definitions of whats \"good behavior\". If people become dependent on social credit to live a functional life, and social credit is dictated by the State's criteria, then you are de facto beholden to behave as the state sees fit in order to live a functional life. If a a corrupt administration gains control it just becomes one more tool they can use to coerce people. No more protest or dissent, no more free speech etc."
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mlhzl0 | why scientists claim that we never detected any alien signals although space is full of all type of waves? | One of the stuff i don’t understand is why scientists claim that space is empty of any life sign but still disregard any wave we receive as natural in origin | Physics | explainlikeimfive | {
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"What they mean is they haven't detected radio (or any \"observable\" frequency) waves that indicate _life_ or _intelligence_. Plenty of things emit electromagnetic waves: our planet just sitting there (without us), emits radio waves. All the planets in our solar system emit radio waves... the sun just pours them out. Other stars, quasars, black holes.. all emit EM waves on various frequencies that we can pick up. But its all just noise, static or fundamental waves at various frequencies depending on what physical mechanism is generating them. Some of these are cyclical or periodic but those typically are following some observable physical period like a spinning quasar or the rotation of a planet. None of these signals exhibit the artificially constructed traces (like a steady carrier wave or regularly repeating patterns) that might indicate someone is doing something or designed a transmitter that is giving off these radiations _intentionally_.",
"We don’t disregard them as natural, we find the sources that create them. For example when we first discover the signal emitted by pulsars we thought they were alien because we had never discover such consistently pulsing and tight band of frequencies before. It seemed unnatural to us at the time. But when we figured out how pulsars worked we realised it wasn’t aliens.",
"We've yet to receive anything that can be identified as intentionally created. No patterns beyond those naturally produced by various stars.",
"Waves intended for communication would have some sort of periodicity to them that the reader would know to look for. Repeating bits of frequency or amplitude that are carrying information. You wouldn’t know how to decode it, but it would be clear that this signal isn’t random. When you look out into space you get a lot of static noise from all directions, but very few periodic signals. When we do detect something that seems more structured, telescopes aim in that direction and try to discern the source. So far, all these repeating signals have been traced to pulsars or local sources on Earth. Non-repeating unusual signals have been detected, but since they don’t stay “on” for very long, there’s no time to examine the source.",
"Aside from the great reasons also given, there are a few other criteria behind this claim. 1st (and largest reason) is time frames. The universe is both extremely young overall, and also incredibly old. We have only known about and used radio waves for approx. 145 years. So as \"advanced\" and long lasting as we think of humanity, we have only really been in the realm of generating and using radio waves for less than 150 years. So any intentional signal we may have sent is only up to approx. 145 light years away. The galaxy is about 100,000 light years across. That's how long and how far we've given other civs a chance to detect us. Its the same, but reverse for them signaling us. A civilization could have screamed out a signal for a million years, but if they were at the wrong distance, sending the signal at the wrong time, the signal would have gone past us before we were capable of detecting it. Or it may not have reached us yet if they were say, in the Andromeda galaxy. The potential overlaps for a civilization being able to generate a signal and any other civilization being advanced enough to detect it at the appropriate time are very slim. Second is signal strength. The distinct signals we detect above the background radiation of the universe tend to be generated by some mind boggling, nigh unimaginably powerful natural sources. Pulsars are generated by the left over cores of stars in some of the most extreme conditions allowed by physics. We could point every transmitter we have in existence at the same point in space and the power we would generate wouldn't even appear on the same graph with that type of signal strength. Any signal that is going to travel across light years and still be strong enough to detect will require an incredibly powerful transmission source. So far the only signals strong enough for us to detect have been generated by powerful natural generators."
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mli10u | Why do people refer to their babies in terms of months after a year, or in weeks after months? | Biology | explainlikeimfive | {
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"A 22 year old is no different than a 21 year old, and not much from a 28 year old. But a 12 month old cute toddler learning to walk upright is VASTLY different from a 24 month old 2T hellbeast toddler who has learned the word ‘no’ and won’t eat their peas. Kids develop so quickly from baby to infant to toddler that you have to define the age range differently. They outgrow their god damn $30 target shoes by the time you drive home with them or Prime can ship a new pair for to you.",
"If a baby is 1 year, 1 month old then that extra month is about 8% of its life. That's not insignificant By the time to get to 5 a month is about 1.3% of your life. Much less significant. To compare, 8% of a 40 year Old's life is 3 years.",
"Because little humans make so much progress in their first weeks/months, and it makes it easier to compare to others. (The comparing your child to others is human. I’m really against it but I also do it myself...)",
"Well, since babies are very young, every month is more \"valuable\" then it would be then if you were, say, 10 years old. That's why parents say their babies are 18 months instead of just saying 1 year. It's the same as turning a year older. When you were a kid, every birthday seemed special and every year was \"valuable\", while if you are 50, turning 1 year older isn't a big deal."
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mlik2q | Why do people normally like sweets less as they get older? | Biology | explainlikeimfive | {
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"My understanding is that part of it is that the ratio of tastebuds change. Children are much more sensitive to bitter, which I'd assume is a biological advantage as children are more susceptible to toxins. As we age, our tastes shift such that we're less sensitive to bitter and more sensitive to sweet. We like sweet the same amount, but we just need less on our palette to get the same perception. This changes again later in life; elderly people tend to prefer more sweet things again as their overall ability to taste declines.",
"I'd venture to say older people continue to enjoy the *taste* of sweets just as much as children, but the side effects such as an upset stomach get worse and so older people become more reluctant to eats sweets because they know they may be uncomfortable later. And even if children get upset stomachs, they don't quite fully make the connected between yummy taste now and discomfort later.",
"The taste receptors for sweet foods develop earlier than other flavors, and is an evolutionary advantage because sweet foods are (generally) more calorie dense. A growing child requires more energy relative to their size than adult does to fuel that growth. When you’ve finished growing the body no longer needs the excess energy and shifts towards maintenance, and looking for proteins, vitamins, minerals, etc—which are more prevalent in savory (red meats, poultry) and bitter or sulfurous (vegetables) flavors."
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mlilzy | Why do things moving fast (ex. fan blades) seem to disappear when they move very fast? | Physics | explainlikeimfive | {
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"It's mostly because of how our eyes work. After we capture light, our photoreceptors have some down time before they can do it again. That means that our eyes have a refresh rate. But each cell is on its own timing, so one receptor will capture the image of the fan blade, while the one next to it will capture an image a fraction of a second later, when the blade is gone from that specific spot. So our brain averages these conflicting patterns out to a semi-transparent blade."
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mlj27p | How does something wind up becoming muscle memory after some time? | Biology | explainlikeimfive | {
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"There is a specific part of your brain (cerebellum) that does that specifically so you can take your higher mind off doing those things."
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mlj3co | Why is glass the material of choice for chemical glassware? | I’m in a relatively beginners-chemistry lab at my school, and it dawned on me that we use glassware to store/conduct a lot of the experiments. Is there a specific reason that glass is the widespread material of choice? Is it just not very reactive? | Chemistry | explainlikeimfive | {
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"Glass can take a lot more heat than plastic. Glass reacts with fewer chemicals than metals. Glass doesn't expand/contract much when heated and cooled. Glass is quite cheap.",
"Glass is extremely chemically inert, has a very high melting point, and doesn’t expand or contract much with temperature changes. It’s unlikely to interact with whatever you’re doing and won’t melt or explode if you heat it or cool it significantly. Materials that do expand/contract with temperature have a tendency to crack if they get too hot/cold. It’s also cheap - so cheap that it’s sometimes still used even in applications where the chemicals *do* destroy the glass because more specialized materials are too expensive."
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mlj6zb | how do small clock radio antennas pick up larger radio waves? | I'm guessing it's either my misunderstanding or it's because even though the radio brave is long the up and down amplitude of any radio station is very small in comparison to the radios antennae otherwise I don't understand how a small thing can pick up the entire range of the radio signal when it's larger. | Technology | explainlikeimfive | {
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"A radio wave isn't literally going \"up\" and \"down\", it's changing electric and magnetic field strengths. It's more like a sound wave (pressure rising and falling), not a water wave (literally up and down). The familiar graphic of two sine-waves at 90 degrees moving through space is a plot of field strengths, not the geometry of the electromagnetic wave. Ideally, you want the antenna to be about the size of the wavelength you want to detect but any antenna is going to pick up \\*some\\* EM waves that hit it and you can make up for under-size antennas, within reason, with good tuners, filters, and amplifiers on the back end."
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mljupu | How do bugs magically respawn every summer? There’s no way they’re hibernating, because their lives aren’t long enough. Are their eggs really lasting that long without expiring, getting crushed, or hatching and dying since it’s not the season that supports them? How does this work? | Biology | explainlikeimfive | {
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"Mosquito eggs can lay dormant for 10-15 years if need be. So, yes. They really do last that long. The process of insect dormancy, as in not in egg form, is called Diapause. Essentially, it's an insect form of hibernation that involves shutting down all processes to a near complete level, and altering their metabolic process to just be enough to keep the insect alive.",
"Some insects have a “super generation” that lives much longer than a normal lifespan. For example, monarch butterflies migrate to Mexico/Central America during the winter. It takes 4-5 generations for them to make it to Canada in the spring, but only 1 generation to make it back in the fall. This super generation then lays eggs in Mexico before dying and they start all over again. Some butterfly and moth caterpillar/larvae go into a hibernation under the snow. They are able to slow their circulatory systems and their blood contains a substance almost like anti-freeze. When it gets warm in the winter, they wake up and go through metamorphosis to become adults.",
"Insects can live much longer when hibernating then when active. Various insects have different ways of hibernationg to increase their chances of survival through the winter. Some do of course die but for the most part they are able to survive even through months of winter, far past their normal life expectency.",
"The main thing that limits the lifespan of an insect is the wear and tear on the exoskeleton. Insects can live for a very long time if they either don't move much (like ant queens)\\* or if they regularily molt (like walking sticks or other insect nymphs). It's only in their final stage of life that insects live for a really short time (just a few months), and that's a tradeoff because an insect with wings can't molt (getting wings is a one-time process and signals the last stage of life for an insect). \\*Or like an insect in diapause. Which is when an insect shuts down most body functions and go into a sleep-like state, similar to hibernation, and wait for better times. Spring for example.",
"Depends on the bug. Bees overwinter the hive, living off the stored honey. Wasp queens hibernate and start a new hive once the weather warms up. Some do lay eggs that last through the winter, or larvae that can survive or hibernate underground. The biological mechanism to not hatch until warm is pretty easy and common.",
"While digging a trench through my garden for an underground cable last month, I was surprised how many different larvae I found as deep as 50 cm, in good shape after a month of frost. Impressive how they managed to munch through the concrete-ish clay the soil is made of."
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mljw8s | What does it mean when people say “Light behaves as a wave or as a particle”? Whats the difference between waves and particles? | I think I got the flair right | Physics | explainlikeimfive | {
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"Light is a wave. It has frequency, wavelength, it experiences interference like other waves, it diffracts. Light is also a particle. It has momentum, it moves in a straight line until forced to change, it bounces off things, it has physical interactions with other particles. So which is it? It's both. Turns out, particles and waves have more to do with each other than we once thought, but [explaining *that* requires a Ph.D. in Quatum Mechanics...]( URL_0 )",
"The traditional particle example would be BBs fired at a small opening that has a paper behind it. As particles they either hit the wall and stop or go through the opening and hit the paper directly behind it. If you were working with a wave though you'd get interactions with the edges that caused little ripples coming from the left and right side which would cause a neat little interference pattern on the wall behind Photons (light) and other \"particles\" (electrons, protons, etc) that you're familiar with do both. If you send light through a very narrow slit it will interact with the edges and cause and interference pattern, but you can also totally model it like a particle in many scenarios. All of the fundamental particles (and many higher level ones) exhibit behaviors like a particle but also behaviors and features of a wave like having a wavelength despite being commonly thought of as a little ball. This is the last semi-sane stop on the Quantum Physics train, its all brain hurty from here",
"A wave is basically a constant \"vibration\". It's a pulse of energy that repeats at a constant interval. A particle is just that: it's a hunk of matter. A little piece of something (usually smaller than an atom). The thing about light (photons) is that it behaves like both depending on how you measure it.",
"Something I think other comments haven't mentioned is locality or position. A particle is always in one place. If you ask, \"Where is it?\" you can very clearly and definitely point to some space and say, \"It's there, it's occupying *this* space.\" Waves, though, aren't really in one space. Sure, you can measure from one wave peak to the next and everything in between is \"this wave,\" but that's not really satisfactory. If someone asks you where an ocean wave is you can point to its general area but when you zoom in, it's kind of in a lot of places. The best you can say is that there's sort of more of it here and less of it over here. That's what's going on in the experiments others are describing. The particle behavior is when they get measured and you definitely find them in one place. The wave behavior is when they're kind of a little bit more here and less there, and when they overlap it's just like an ocean wave - places where there's more add up to be a lot more and places where there's less add up to be a lot less, and more and less together cancel to make a neutral flat lack of wave. Depending on what you're doing to elementary particles, sometimes you find them definitely for sure right in one place, and sometimes their location is kind of smeared over an area and they're just *mostly* here or there, maybe.",
"Imagine you've got a 1x1x1 cube. And you allow one photon of light into that cube. You would expect that photon to be one individual particle inside the cube. But when we do experiments, it's not, sometimes it's one individual particle, sometimes it's one individual wave. The delayed choice quantum eraser is the one experiment I *need* a solution for in my lifetime.",
"There are several differences in the way that waves and particles behave. For example if a particle gets close to an edge it will just continue straight forward while a wave will get diffracted and spread out on the other side. If two particles meet they will either pass by each other unharmed or hit each other and bounce in different directions while if two waves hit each other they will join together and form an interferance pattern. A particle does however only exist in one single spot while a wave stretches out over a larger area and can move in different directions at the same time. They behave completely differently with maybe only sharing the property of reflection. What is odd about light is that it have properties of both. When we observe it, for example by capturing its effect on a piece of film, we can see that it impacts only single points on the film and we can even count the number of photons that hits each part of the film. However in the parts of the experiment where the light is allowed to travel without getting directly observed it behaves like a wave. It will diffract and interfere with itself just like a wave, but when it hits the film at the end of the experiment it is a particle."
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mlk2yr | Why is gold shiny-yellow but most of the other metals have a silvery color? | Chemistry | explainlikeimfive | {
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"Basically, because gold has an electron transition (two different levels the electrons can be in) that corresponds to blue light wavelengths, so gold absorbs a little blue and the reflected light looks yellow as a result. Most metals don't absorb within our visual range so they just act like mirrors, reflecting all colours. A few have electron transitions that can absorb visible colours...the lack of those in the reflected light is what gives them their colour. It turns out the detailed chemistry of this takes you down a horrible rabbit hole of correcting quantum mechanics for the relativistic effects of moving electrons. It gets messy in a hurry.",
"Materials rarely reflect all wavelengths (colors) of light equally. In gold, there's a sudden drop off once we reach the part of the spectrum that we call \"blue\". This means that colors in the red and green areas are reflected, which combined appear yellow. Silver, for example, drops off in a similar manner, but the drop off point is outside the range of visible light. Since the light we can see is a very narrow slice of the spectrum, few metals have such an uneven distribution. If we could see more of the spectrum, they would look more varied. Why the reflected light varies in a particular way is more complex than my understanding of physics can explain.",
"While there is already a [great top level answer for the chemical side]( URL_1 ), there is another component that could be a top-level answer. In the question you state \"most of the other metals have a silvery color\". This idea is probably just because you've not worked with metals. They can appear metallic which includes being reflective, but various metals cover the rainbow. Silver is only \"silvery\" when freshly polished or cut and highly reflective. Naturally it can be anywhere from white to black, but can also appear as a pale green or yellow. Polished silver is highly reflective, nearly white. For better or worse people generally associate mirrors and reflectivity with silver. The raw elemental colors vary based on how they cool and bond together. Their various chemical lattice structures result in different colorings. The way the metals are finished and oxidized on their outer layers also affects the colors it appears. Since metals oxidize to different colors (metals develop an oxidation layer almost instantly in the air) the oxidation levels can give an additional semi-transparent color in addition to the layers below it. Iron can appear reflective like silver, but the underlying color can generally be white to black, and also commonly red, brown, green, and blue. With 11 oxidation states and a bunch of potential bonding options, iron can appear any color of the rainbow. Example from a Wikipedia image showing a rainbow of colors just by changing the temperature of the metal as the bonds form and cool: [image clicky]( URL_0 ) Copper was mentioned by other posters, the most common colors are coppery and green, neither is \"silvery\". Cobalt wasn't mentioned. It can appear as a pale reflective color that's somewhat silvery, but can also appear black, blue, green, red, and even bright pink. Blue cobalt has been used in art for millennia, and pink cobalt is mixed into a bunch of pigments. Polonium has black, yellow, red, and purples. Sodium is more of a white to yellow color. Lithium goes reddish. Tin is white, ancient names for it translate as \"white lead\". Etc., etc. Metals can be reflective, and while it's easy to associate \"reflective\" with \"silvery\", they have far more color when you look deeper.",
"Relativity! Gold is a heavier element than the other \"coinage\" metals (copper and silver). Heavy enough for relativity to become a factor. What does that mean? Electrons near the center of a gold atom \"move\" at speeds that are significant when compared to the speed of light. What this means is that electrons close to the atom are pulled in. Electrons hate each other, so when it's crowded around the center of the atom, they push others out further than lighter atoms do. This changes the spacing between electron shells, in terms of energy, where electrons want to hang out. Add to this another effect, that electrons in \"orbit\" around an atom have some spin. In heavy atoms, like gold, this spin and orbit spin combine in ways that light elements don't so much. This, too, changes where electrons like to hang out, more so than, say, lithium. Think of it like a you're an electron at a school cafeteria, with so many seats at a table, and if you're not cool enough, you can't sit there. Because gold is so \"heavy\" (protons), it pulls some tables closer, and pushes some further away, and it changes the number of seats at those table in ways non cool kids that aren't gold can't do. Combined, a heavy (lots of protons) making closer electrons move fast (compared to the speed of light), and the mixing of orbital spin and intrinsic electron spin, changes the color of the atom. What does the color of an atom mean? Well, it's what light it absorbs, vs what light it passes. Silver absorbs light that isn't visible, in the ultraviolet spectrum. Gold, because it's a fat fuck, shifts that color towards the visible spectrum, and looks yellow.",
"There's a limited amount of colors to metal to begin with, both gold and copper stand out as having an unusual one. They absorb more blue light than other metals, and as a result their apparent hue skews more towards yellow. The actual physics of that are beyond me to explain as an ELI5, but basically the elemental structure of those metals cause them to absorb more blue wavelengths. Also keep in mind that many metals you see are alloys, so most aluminum or iron based ones are going to appear silver. Bronze is a noticeable copper based exception, and appears golden as well",
"At the risk of being too simplistic, gold absorbs blue light. Most metals do not absorb any visible light. Therefore gold reflects back mostly yellow light and other metals reflect everything back. As for why that is the case, it involves electron transfers and some complicated chemistry and quantum mechanics. Not really ELI5",
"Can we reliably predict the color a material if we know its chemical form in enough detail?",
"Metallic gold has an unusual colour because it's high density means the electrons go faster around the nucleus than the electrons in lighter metals. As the electrons approach the speed of light, school level physics doesn't explain everything and the more complex theory of relativity is needed. This leads to \"relativistic effects\" including the unusual gold colour. Cesium is another heavy metal which is also gold in colour when pure.",
"Gold appears to have a color because it has a perfect slot for a type of light that we can see. You remember those shape sorting toys? There might be a star, a square, a circle, etc., each color we see has it’s own special slot. Most metals don’t have any slots for any colors we can see, so they just reflect everything. The slot is a difference in possible energy states. Each individual jump in energy can only correspond to a single wavelength of light. Different colors are different wavelengths of light. The wavelength of a light particle corresponds precisely to the energy of that light particle. When an electron makes a jump in energy in a material, it requires some external energy coming in or or going out to balance it out. It requires exact change. Some wavelengths of light are visible, many more are not visible. So a cliff of a specific height can correspond exactly to a given energy per particle and therefore wavelength of light."
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mlkn9a | what do spiders eat in bathrooms? Do they starve if nothing falls in their web? | I have always wondered why spiders prefer to make webs in bathroom corners and I somehow feel sorry for the little guys - I have never seen a fly or other insects in my bathroom and I can't help thinking my spider-bros will starve. Do they? | Biology | explainlikeimfive | {
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"They’ll eventually ditch the web and try again elsewhere if there’s slim pickings in that spot. You’ll know if they’ve been successful because they don’t eat the exoskeletons and so pieces of bug armor begin to collect beneath active webs. They like humidity because the water helps keep the web material pulled tight. It’s harder to keep a web taught when it’s very dry. Some household bugs like silverfish are also attracted to moisture.",
"Simple answer is that they are just more noticeable in the bathroom as there isn't exactly much furniture in bathrooms but bare walls. They are pretty much in same numbers perhaps even more outside of bathrooms but you don't get to notice them as they are mostly outside of our vision hiding behind furniture, paintings, clocks etc.",
"One factor is that arthropods need very little food compared to, say, mammals. A single gnat or springtail, too small for you to notice, wandering into the web is enough to keep the spider going. It takes a couple of weeks to starve a spider to death, so if it doesn't get anything for a couple days, it heads out. At least the bathroom is humid, which was good for it. Think on this - the glue on the back of a postage stamp can keep a cockroach alive for a month or more, and spiders are far less active animals than cockroaches, so don't burn as much energy. (Also gnats provide more nutrition than glue.)"
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mlmtyi | What happens when you tune a radio? How do the frequencies change? | Technology | explainlikeimfive | {
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"The station frequencies don't change, but by tuning you are adjusting the receive part of your radio to become sensitive to a certain frequency you want to hear. Inside the radio are parts (capacitors, inductors and resistors) that allow this resonance frequency to be set.",
"The basic idea of most radio systems is \"frequency division multiplexing\", that is, different channels of information propagate through the air all at the same time but can be separated out from each other because each channel's information is confined to a different part of the radio frequency spectrum. So the general job of a radio receiver is to allow the user to control which part of the radio spectrum to \"listen to\", and to block out all the other parts, so (only) the material of interest can be received. We generally call this \"tuning\" on a radio, \"changing the channel\" on an old TV, etc. If you want to transmit radio information, you generally need to get a license, which will specify what frequency band you are allowed to use, how much power you can transmit with, and what modulation scheme you will use for your signal. Some licences are easy to get, while others are scarce, expensive, and/or require certification and training. Receiving radio usually requires nothing more than the equipment itself. The technical specifics of what the radio does to \"tune in\" a particular signal depend on what is being received. An old-style ham radio station will turn a carrier wave signal on and off rapidly to convey \"dots\" and \"dashes\" of the Morse code. An AM (amplitude modulation) radio station broadcasts a constant frequency carrier wave whose amplitude varies in such a way that it carries the sound or other signal. An FM (frequency modulation) radio station broadcasts a carrier wave whose frequency varies slightly; this variation carries the signal. There are many other schemes. Each requires dedicated circuitry that can lock on to the carrier wave of interest and then extract the original information (audio, video, dots and dashes, digital data, or whatever was sent). Radio is actually a wonderous and amazing technology, though we kind of take it for granted now. I imagine it must have revolutionized the world in the first half of the 20th century, allowing far-flung people to instantly connect with each other for the first time.",
"The wiggle trapper looks for and traps different speed wiggles. This is tuning a radio. The radio waves are wiggles. Y’all really know some genius 5 year olds if you think anything more complex will make sense.",
"Depends on the radio receiver, there are multiple designs. If you have an old radio with a physical knob, it likely changes the value of one or more variable capacitors, which will change the resonant frequency of parts of the circuit, like a filter or local oscillator. Often you get coarse filtering with a variable filter, then mix the incoming signal with the output of a local oscillator, before putting it through a much more selective fixed frequency filter. For more information search for \"superheterodyne receiver\" Though for modern devices, it's also possible to use software defined radio, where you have some RF front end, but put the signal into an ADC so you can use more general purpose hardware to do the heavy lifting.",
"The radio station mixes the audio (voice/music/etc.) with high frequency noise (the exact frequency is the radio dial number like 101.1) and sends it out over the airwaves. Your radio receives this mixture and if your're tuned into 101.1, the radio removes that frequency noise leaving just the audio for your enjoyment."
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mlmv8u | Why routers still take so long to power on in 2021? | I remember dial up connections taking at least 2 minutes to connect, plus the time it took for the computer to turn on. However, with broadband and fiber internet I'd expect everything to be faster. How come routers still take so long to stabilish a connection nowadays? | Technology | explainlikeimfive | {
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"text": [
"routers are basically running a lightweight linux (or whatever) computer inside of them and they need to boot up just the same."
],
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18
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mlmy6h | What is happening in your body when you physically feel dirty? | Biology | explainlikeimfive | {
"a_id": [
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"text": [
"Basically, nothing. It’s all in your head. Which makes sense, because that’s where your brain is. Your brain is your body’s grand commander. It makes sense of everything your body tells it, and sends back signals. You don’t actually “feel” things with your body - you feel with your brain. Your body just sends up the message and your brain interprets. Whenever you get a signal from any receptor - taste, smell, sight, touch, or sound - your brain follows the same protocol. It receives the information from your receptors and immediately begins to cross-reference with any other information coming in, as well as with your memory. If you get a pain signal coming up from your hand, for instance, your brain reaches for your sight - I’m standing in front of a stove - and hearing - sizzling sound - and smell - can smell the gas cooker is on - and memory - I was just cooking pancakes, and I’ve burned myself before, and this is what that felt like. It assembles all these things in a fraction of an instant, and sends back “PAIN, MOVE HAND!” When you “feel” dirty, the same process is happening. Your brain is assembling the memory of what you’ve been doing all day, the “tired” signals from your body, the smell of BO from your body, the memory that you usually shower at this time of day and the memory of how pleasant the warm water feels, etc etc, and it all comes together to send out a generalised “you have a thin layer of scum over your body” kind of sensation. Because brains are weird like that."
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mlnb56 | How does oxygen in a scuba tank get compressed at high pressures deep underwater, when the tank itself stays closed and the same size? | Physics | explainlikeimfive | {
"a_id": [
"gtme3jv"
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"text": [
"The gas in the scuba tank doesn't get compressed by going deep underwater. It's filled with pressurized gas while it's on the surface, and its pressure doesn't change with depth."
],
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10
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mlnbmn | How do dishwashers clean everything so thoroughly? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"It's a combination of high pressure hot water sprayed over and over and over again, and a detergent in the water that breaks down grease and food particles and dissolves them into a solution in the water to be drained away. Even without detergent, just the hot water spraying repeatedly for the cycle does the majority of the work."
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mlo9by | how DDOS protection works | I went to a website and it redirected me to a page that said, “wait for up to 5 seconds to be redirected,” and then, approximately 5 seconds later, I got to where I wanted to go. When I looked how it worked, I got a whole bunch of technobabble that I couldn’t understand. What exactly is happening during those 5 seconds? How can it tell the difference between me, a legitimate user, and an attack? | Technology | explainlikeimfive | {
"a_id": [
"gtmks85"
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"text": [
"Imagine you're calling a friend, but so are spammers. So many spammers so that every time you call, you get a busy signal and you can't talk to your friend. That's the DDOS. But a new guy says, call me instead and I'll patch you to your friend when I hear your voice so I know it's you and not some guy trying to sell her ephedrine diet pills. That's the protection. It's an intermediary that filters out bad traffic and only pushes the good traffic. There are a lot of methods on how they do this, usually requiring machine learning and/ or IP databases of known bad actors / previous denial of service traffic logs, etc."
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mlonnt | What do “sound guys” at live concerts do? | Technology | explainlikeimfive | {
"a_id": [
"gtmn1bk"
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"text": [
"There are separate mikes for each musician and singer. The sound guy adjusts the volume for each of them. They make sure you can hear the singer over the drums, that sort of thing. The volume you get into the microphone is based on how loud the person is plus how close the microphone is to them. So you don't want to just let them all play at whatever sound level they happen to get."
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mlooh9 | how are travel pigeons trained to travel long distances and know where to return to, like the way they were used during the world wars? | Other | explainlikeimfive | {
"a_id": [
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"text": [
"They aren't trained. Homing pigeons instinctively find their way home. So you just raise them in a place. Then when you take them some place else they fly to their home. No training required. But they do one way trips - back home. They don't fly someplace else and then come back.",
"They didn't really need to be trained at all, which was the good part. They just found their way home through methods still somewhat mysterious. Of course this meant that if you wanted to send a message somewhere you needed a pigeon that nested there to attach it to. You couldn't send pigeons to arbitrary locations, they only went home."
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mlowca | How does pressing leaves make them last? | I pressed some leaves by placing them in a book and placed a lot of weight on it for a month. Now the leaves are framed. Why does pressing leaves preserve them? Why wouldn't they wilt or decay either during the press or now that they are framed? | Biology | explainlikeimfive | {
"a_id": [
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"Pressing leaves essentially dries them. You can do something similar by hanging them upside-down by their stalks in a dry place. The reason you press them between paper is to make them flat so they can be framed. The pressure helps the moisture to seep out into the pressing paper, which wicks it away. Once there is no moisture in the leaf, there is nothing to appeal to fungus or bacteria. It is just a husk of cellulose. Eventually it will disintegrate if you leave it exposed, but it can last a very long time kept safely under glass."
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mlowm3 | Why is a sepsis so dangerous? Can't we just filter the bad stuff out? | Biology | explainlikeimfive | {
"a_id": [
"gtmpqgg",
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"We currently have no way for doctors to filter out good things and kill bad things. We need to rely on the body to be able to detect the bad things. If the body starts getting real into it and killing everything, then it may start killing good things as well as bad things. This killing of good things is sepsis.",
"Sepsis isn’t the infection itself, it’s the body’s reaction to an infection. One of the main ways the body fights off infection is by slowing activity to that localized area, so that the infection isn’t spread around, you don’t bleed out, and a few other reasons. That’s fine for skin and other redundant/widespread organs and functions that are more likely to get infected. But it’s a large reason why singular unique organ infections (think liver, kidney, brain, etc.) tend to be bad. With sepsis, your whole body can treat itself as if it’s infected, slowing down your brain, liver, kidneys, etc. all at the same time. And those reactions are caused by molecules. There’s no good way to remove/destroy specific molecules in the bloodstream without basically destroying the blood, just like there’s no good way to remove/destroy the color dye molecules in a soda without rendering the soda entirely unlike soda.",
"Sepsis is an infection in your blood. Bacteria are very dangerous in your body. They are very, very tiny - smaller than some of the cells in your blood. You body will do anything to keep them out of your blood, because once they get into your blood they can travel around your whole body. Your body tries to keep the bacteria in one place so that it can fight them. We can’t filter out the bacteria because they are so small. We can fight them with antibiotics. But the problem is that they multiply so rapidly, and if they are in your blood, they are through your whole body. That means that you are very, very sick and your body may go into shock. Septic shock is almost always fatal. It’s a reaction to the bacteria being everywhere. It’s like a storm inside your body, as your brain hits emergency buttons at random in a panic, and accidentally kills you in the process. It’s very hard to reverse that while a person still has bacteria in their blood.",
"Sepsis contrary to popular belief isn't referring to the infection but the response to it. Sepsis can broadly be considered an immune system overreaction to an existing infection which in turn causes damage. You could for example have an infection in your urinary tract that spreads to a kidney, pathogen associated molecular patterns (PAMP's) and damage associated molecular patterns (DAMP's) are released into your bloodstream when infectious agents or your own cells are damaged. Think of them as the really common bits of dead pathogens or cells your immune system is trained to recognize because they're so common. As these are floating around in your blood your white cells find them and begin an immune response. However instead of getting a localized response at the site of infection, you get a wide-ranging response across the whole body. So instead of localized swelling, fever, and all the other stuff you associate with an infection, you get that across your whole body. This can lead to a whole host of problems, but top of the list are organ failure, and hypotension (low blood pressure). So to answer your question. Doctors can't just filter the infection out, because most of the time the infection isn't actually blood-borne. And even if it were most bacteria are smaller than the cells in your blood, meaning any filter would also catch the components you need to survive."
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mlp2xf | ; How do spiders make silk? How do they use it to make webs, and how do they make their webs so intricate? | I was in the shower and I suddenly had the horrifying thought that spiders make silk out of digested flies. I need someone to tell me I’m wrong so that I can sleep at night again. | Biology | explainlikeimfive | {
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"text": [
"Well... technically, they do, in the same way you make yourself out of what you eat. Every animal eats in order to get the base nutrients it needs to survive and function, and then repurposes those ‘building blocks’ into something new. It’s like recycling. Or like ‘the great circle of life’ from the Lion King. Spiders spin webs out of silk, which is made up of special proteins that they keep as a liquid in their silk bladder. These proteins lock together in an incredibly strong silk strand as they pull it out of their spinneret. They have several kinds of silk they can spin - sticky kinds and strong kinds. As for how they make their webs so intricate: well, it’s a complicated answer. Spiders are born knowing how to spin webs. The patterns are imprinted in their brain before they are even hatched. It’s in their DNA. This is called *behavioural inheritance*. We’re not really sure how it works, but lots of creatures have it - including humans! Every spider just “knows” how to spin its own web. That’s not to say they’re immediately good at it. Juvenile spiders have to practice to get it right."
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mlp8cg | why are we more tired when we do things in the heat vs in the cold? | Wouldn't it take more energy to make cold muscle move vs a warm one? | Biology | explainlikeimfive | {
"a_id": [
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"text": [
"Because your body has to do the work and dissipate more heat into an already heat rich environment. The colder the environment, the more the environment helps cool you and the less work your body needs to do to release the heat."
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mlpmq2 | Why do Humans and Animals need heat? | What does being warm do for us? | Biology | explainlikeimfive | {
"a_id": [
"gtmsai7"
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"text": [
"Many of the chemical reactions in your body only happen in a certain range of temperatures. In particular, enzymes - which accelerate certain reactions by a factor in the thousands - often only work within extremely narrow temperature ranges, which means the reactions they support effectively shut down outside those ranges. This means your body needs to maintain a fairly narrow range of internal temperatures to function normally. Humans, as mammals, are endotherms (\"warm blooded\"), so our body regulates its own temperature by things like sweating or shivering. We also have behavioral cues: if you're cold, warm feels good; if you're hot, cold feels good."
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mlpum4 | Why are Magnetic Resonance Imaging (MRI) machines so incredibly loud? | ELI5: Why are Magnetic Resonance Imaging (MRI) machines so incredibly loud when they are operating? | Technology | explainlikeimfive | {
"a_id": [
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"gtnnhwh"
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"text": [
"The magnetic fields used are extremely strong. To get good image the machines use a minimum amount of steel. Applying huge forces on plastic parts causes them to flex. Flexing them back and forth makes noises.",
"The MRI magnet is always on, whether it is making a noise or not! There is 2 magnetix parts to making an image with an MRI. The static magnet, eg the 3 Tesla, provides the base. The second part is called the magnetic gradient. This is a very small magnetic field on top of the 3T that makes small changes in magnetism along the length and breadth of the magnet. This is what allows the image to be formed. The gradient is turned on and off rapidly. This is done by pulsing a current through the wires wound around the magent. This current pulsing gradient causes the wires to oscillate and create this loud sound. For faster image acquisition, a higher current is passed and this causes louder sounds."
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mlpyyw | How do people actually die from dementia/Alzheimer’s? | I know that dementia and Alzheimer’s cause a significant mental decline but what does it physically do to the body? Does the brain just stop telling the body how to function? | Biology | explainlikeimfive | {
"a_id": [
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"text": [
"In the end, basically for either/both, yes, the brain forgets to function key organs and the person dies. You should be aware that Dementia and Alzheimer's are not the same thing. Dementia is the decline in mental ability. Alzheimer's is an actual disease, which can cause dementia. I had a father in law with dementia and my pops has been dealing with it for a few years and is closing in. Neither had/has Alzheimer's though. If someone you know is dealing with this I cannot recommend it enough for them and their friends and family to go to therapy or group or have some safe outlet to discuss what they are going through.",
"The brain literally disintegrates, it shrivels up like a raisin in the sun, it's awful, the disease itself is fascinating, but what it does to people, it's bloody heartbreaking. I believe Mad Cow Disease & Dementia/Alzheimers has similar symptoms. The last time i read about the disease was a few years ago, someone else may be able to comment.",
"With Alzheimer's, yes, the body stops being able to do the stuff it's supposed to do. The person forgets/loses the ability to swallow, for example. They start getting more and more problems, like they might breathe in food particles into their lungs, not be able to cough them out because their body doesn't know how, get pneumonia, and die. Or they stop being able to pee right, get a urinary tract infection, and die. Basically, you're talking about old people who are already fragile, and they have no way to perform the normal bodily functions, so things start breaking down and they die."
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mlqi2k | Why do we have to pee more as we age especially in the middle of the night? | Other | explainlikeimfive | {
"a_id": [
"gtmxzk9",
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"text": [
"And what can we do about it? Asking for a 58 year old guy.",
"So basically your colon is shaped similar to a donut. And you bladder has a reservior if you will that sits above it and a small pathway that leads directly through the hole of this donut. As we age, your prostate grows in size. This enlarged prostate means theres less room for urine to accumulate, and as a result, we get to the \"oh crap, i have to pee NOW\" stage a lot faster. The bummer part is, we often pee slower, in lower volume and have a harder time urinating as we age. Fortunately, there are cheap, relatively simple medical procedures to help with this."
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mlqqm0 | What exactly is art deco? | I keep hearing how this painting or that building or that sculpture is art deco, but it's never very clear to me what exactly makes them art deco. For example, the Chrysler Building, Christ the Redeemer in Rio de Janeiro, and the mural on the ceiling of the Rockefeller Center lobby are all described as art deco, despite none of them having anything in common. What should I look for in a work of art or architecture to identify it as art deco? | Other | explainlikeimfive | {
"a_id": [
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"text": [
"> despite none of them having anything in common They have certain design elements in common-- strong geometric lines, a sort of \"futuristic\" aesthetic as perceived by people of the time, and a sort of flashy optimism. Even the Redeemer statue is recognizable: compare it to something like Michelangelo's David. It's still a lot sleeker and sort of abstracted from a purely realistic human body. But as much as art deco can be identified visually or by the materials, it's also largely a product of a certain era-- about the 1910s to the 1930s. If something was made with the trendy architecture of that era, you can almost guarantee it will be a part of this movement.",
"From Google the predominant decorative art style of the 1920s and 1930s, characterized by precise and boldly delineated geometric shapes and strong colors and used most notably in household objects and in architecture.",
"Here are some signifiers of art deco. Everything is a bit geometric and abstract. Symmetry and geometric patterns are common. Art isn't realistic. Big bold shapes like starbursts, fans, zigzags, and arcs are used as ornamentation, like the [top of the Chrysler building]( URL_2 ). Here's a [statue of Icarus]( URL_1 ), notice how the wings are just geometric shapes and the pose is not naturalistic.[ Christ the Redeemer]( URL_0 ) isn't as obviously art deco, but the perfectly symmetric pose, the geometric straight lines of the lower robe, and the sharp, un-fabric-like folds of the upper robe point to art deco influences. Rich materials like ebony, ivory, gold, and inlaid wood are used, as well bold and \"futuristic\" materials like chrome and polished metal. Combine that with the geometric influences and you get stuff like these [patterns]( URL_3 ) or the floor in [Rockefeller Center]( URL_4 ). Generally, stuff looks like futuristic, or at least what what people thought was futuristic a century ago."
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mlqsyy | How do DVDs and CDs work? How do they know what to play? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Let's start with describing a record player / phonograph. A record has a groove in it that has bumps and grooves in it. You can even see it here: [ URL_0 ]( URL_0 ) The movement of the needle in the record groove gets transmitted directly to the movement of the speaker. When the needle moves up, the speaker is pushed out. When the needle moves down, the speaker is pulled in. Do that very quickly and you can reproduce any sound. A CD is actually a very simple device that accomplishes the same thing, digitally. Just like a record, it's a flat disc that has a \"groove\" in it. But instead of the groove moving up or down, the CD has a pattern of holes that can be detected by a laser. The holes encode the same information as the record does, but digitally, using binary code. Think of it this way: suppose the position of the record groove could be \"high\", \"medium\", or \"low\". Those could be represented with dot patterns like \"dot dot\", \"dot blank\", and \"blank dot\". To be specific, a CD records a 16-bit binary number, once for the left and the right channels, and it does so 44,100 times per second. Those numbers are read by a laser and fed into a DAC (digital to analog converter) that can be used to move a speaker. A DVD is a lot more difficult. A DVD stores things in a similar manner as a CD, it's just more dense. It stores about 10x as many bits of data. But the idea is pretty similar. However, the actual interpretation of those bits is a million times more complex. While a CD has a pretty straightforward encoding of an audio signal that can be implemented by a pretty simple digital circuit, a DVD has a very complex encoding of a video. Decoding a DVD and turning it into a picture basically requires something as complex as a full computer. It's a very complex algorithm that takes a highly compressed digital code and uncompresses it to result in a series of full-color video frames that can be sent to a video screen. Plus the audio too."
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mlqynf | Why are hang overs worse on an air plane | Why is it that hangovers get wat worse when you fly? | Biology | explainlikeimfive | {
"a_id": [
"gtn0z5r"
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"text": [
"Dehydration. Airplane air is notoriously very dry, like Sahara desert dry. Hangover is mostly lack of hydration hence adding dry air 'makes it worse'. You're probably also drinking not a lot of water etc since waving down the hostess and getting a tiny cup is not quite the same as hanging over the toilet in the comfort of your own home."
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mlrkbo | Why is it accepted that some commodities can fluctuate in price daily, (like hotel rooms or gas), but others are expected to stay relatively stable (Windex, batteries, an iPhone)? | If Apple changed the price of the iPhone based on daily sales, people would lose their minds. It would be considered price gouging. So why is that same behavior considered ok when it comes to certain other commodities? | Economics | explainlikeimfive | {
"a_id": [
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"Apple certainly decides how much the next iPhone is going to be priced for, based on popularity / sales of the previous year's iPhone. Likewise, a grocery store certainly updates prices regularly based on demand as well (go check out the 'clearance bin' if you don't believe me). So demand-driven pricing still applies to all those things, but you generally don't see it because it happens on a much slower time scale, and you're not regularly buying those things. What's special about the items that you do observe price fluctuations on, is that those items are based on _immediate delivery_ of something that has a _limited supply_. For those industries, the price fluctuates much more quickly. Also, when a local sports team near me moved from standardized ticket pricing to dynamic ticket pricing, the local media / fans _did_ go apeshit. We complained and yelled. And then we got used to it, and bought the tickets. So I guess the real answer is, that behavior is ok because we let those companies get away with it.",
"Most of the answers here are insanely muddled for what is such a simple explanation: Both the supply and demand for Windex, batteries, and iPhones is relatively stable, so the price is relatively stable as well. The supply for hotel rooms is relatively stable, the but demand is highly variable, so the price is variable as well. Both the supply and demand of gas is highly variable, so the price is variable as well. All that nonsense about one or the other being \"commodities\" is wrong- commodities can be as stable or unstable in prices as anything else. Also, what makes something a \"commodity\" is interchangeability- so if you don't really care what brand battery you're buying (which, in an emergency, you probably don't) then batteries are effectively a commodity as well. So is Windex. Case in point: When toilet paper became scarce, nobody was worried about what brand they were buying. It wasn't one brand that was sold out, it was all of them. As for people being offended by \"price gouging\", it's not really a rational position in the first place. Higher prices during emergencies have several useful functions, such as encouraging people to only buy what they need instead of hoarding, encouraging people to stock up on non-perishable items ahead of time, and encouraging stores to increase supply, and encouraging outside companies to send in higher supplies ahead of predicted emergencies. The truth is that the prices of batteries *should* rise during emergencies, but people aren't used to batteries changing prices, so they get mad and pass laws against it. The price of",
"Commodity prices are more volatile because they are usually **simple, unfinished goods**. So the price is intimately tied to the supply of the commodity. If sugar crops fail around the world, sugar in your grocery store will become more expensive. But now imagine a large conglomerate like Nestle. They have already stockpiled large amounts of sugar, or have contractual agreements to buy sugar at regular intervals for set prices. Even if sugar crops fail, they do not need to raise prices for their candies. And even if they did choose to pass on the cost of sugar, it's a very small component of the price. But why some things are accepted as custom is usually about what's normal. We all accept that gas prices fluctuate all the time, but after a hurricane (when supplies are disrupted and demand is through the roof) people are upset if the price changes. It's not necessarily rational.",
"There are three factors: 1. Supply and demand. The longer a span you can predict demand, the easier it is to keep prices stable. 2. Shelf life. In the case of a hotel room, either it's sold tonight or it isn't. In the case of the fruit in the supermarket, if it isn't sold fast enough it will go bad. Glass cleaner can pretty much sit on the shelf until it's sold. iPhones go on sale when a newer model is about to come out. Except... 3. Pipeline capacity. Stores put winter items on sale at the end of winter because they have more profitable things to do with their space than let winter stock sit there all summer. Refineries sell gas cheaper when they know they need to make space for the next contracted crude delivery. For expensive infrastructure, it's often more profitable to keep it running even when marginal profits are lower."
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mlro8x | About Leasing a car | Other | explainlikeimfive | {
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"The \"down payment\" on a lease isn't refundable, it's a prepaid portion of the total leasing cost.",
"Answer: Leasing is just renting a car for a long period of time. Your down payment just made your other payments smaller. You paid 10k + monthly fees to use the car. You can go back to the dealership and see if they will give you a deal, but you may also be required to do another down payment. It is sunk money and you won't get it back."
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mlujz8 | Surface of a river has different wave patterns at different points. | When I looked across a river at my hometown I observed that some areas had small patches where the water appeared more calm. | Earth Science | explainlikeimfive | {
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"Different portions of the river have different elevation changes, different widths of the river, different depths and landscape, and different weather."
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mluk81 | How come when you wash a cut, it kills the bacteria but not the cells trying to heal the cut? | Biology | explainlikeimfive | {
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"It doesn't kill the bacteria per se. Soap will stick to the bacteria and make it easier for water to wash it away. But yes when you rinse a cut you are washing away immune cells and bacteria, but you have tons of immune cells and only very few bacterial cells trying to infect you. On top of that it washes the bacteria away from the area around the cut, further decreasing the infection risk.",
"Washing a cut doesn't kill the bacteria. It just helps rinse the bacteria off your flesh down the drain. When you use antibacterial products however it does also kill some of your own cells along with the bacteria, but it's OK because you'll heal."
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mluoup | Why are moths so intensely attracted to sources of light? | Biology | explainlikeimfive | {
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"text": [
"It is believed that they use moonlight to navigate, since they are nocturnal. They mistake bright lights for the moon. I'm not sure if anybody TRULY knows, but this is commonly accepted."
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mluvfd | How does Internet archive work? | URL_0 On this website you can see old snapshot of particular website. How do they maintain it? They crawl the web and save copy of each website? | Technology | explainlikeimfive | {
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"Yep, that's literally it. They webcrawl constantly. With some internal logic that decides how often to crawl sites, how deep, and what images and similar do or don't get saved. And it's all stored compressed and decompressed when you want to retrieve a site. It's still tens of petabytes of data but it's manageable. They also apparently use Alexa Internet crawls (they're the the guys who rank websites) as well as their own to find sites to archive."
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mlx0wy | How are internet speeds regulated by the service provider? | Technology | explainlikeimfive | {
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"It can be done in simple software settings in the routers that direct the traffic to you. They limit the amount of data to you. Extra data Thai is not forwarded can be stored in a memory buffet or simply dropped. That is if the speed is artificially limited and not because of a slow link."
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mly455 | Why is mayonnaise not high in protein when it's mostly just eggs, which are very high in protein. | Biology | explainlikeimfive | {
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"To make mayo, you use about 200-300 ml of oil per 2 eggs. This makes it obvious why its not a good protein source. The amount of eggs is too small in comparison to the fats.",
"Most of Mayonnaise is mostly oil/fat, eggs are of course an important ingredient but it's overshadowed by the amount of fat in it.",
"Also, by mass, eggs aren't that great a protein source. They're about 12% protein by mass, nuts and beans being higher than that, while meat is usually 25% or more (depends on the animal and cut)."
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mlycue | Why and how does alcohol have all the effects we know it has (disinhibiting, loss of balance, impaired vision, etc.)? | How does alcohol 'work'? From the moment you drink it. | Biology | explainlikeimfive | {
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"text": [
"It influences many neurotransmitters in the brain dependent on the dose. It impacts on the way your brain send signals to the body. Mainly it works on GABA in the brain and body which in excess can make you sleepy or disinhibit you. It works on other neurotransmitters too."
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mlyinx | How does skin hydration work ? | I'd like to ask you how does skin hydration work and are there any drawbacks of using products of skin hydration, not because of the other chemicals that the product might contain, but because of skin hydration itself. | Biology | explainlikeimfive | {
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"text": [
"Skin cells absorb water, but not oil. Most products are a combo of water plus oil plus emulsifiers that keep the product from separating. The water gets absorbed, but the oil stays on the surface of the skin which \"seals\" it in a way, reducing evaporation of the water that was absorbed."
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mlyjs4 | In solar PV, what is Maximum power point tracking? | Physics | explainlikeimfive | {
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"Solar cells have a certain efficiency sweet spot, and MPPT (maximum power point tracking) is a strategy to find that sweet spot. They put out a certain amount of voltage and current and the more current you draw, the more the voltage will go down, but it's not a linear relationship. If you find exactly the right amount of current to draw, you maximize how many Watts the panel is able to deliver. * If you draw 0.1A from the panel, the voltage may be 28V, so that's 0.1A * 28V = **2.8 Watts**. * If you draw 1A from the panel, the voltage may be 20V, so that's **20 Watts**. * If you draw 1.2A, the voltage may be 18V, so that's **23.6 Watts**. * If you draw 1.4A, the voltage may be 10V, so that's **14 Watts**. In this example the maximum power point or sweet spot would be right around 1.2A and 18V. If you draw more or less current, you're wasting power. This sweet spot varies with the intensity of the light and the temperature of the panel, so it's not always the same. MPPT controllers constantly play around with the amount of current that's drawn from the panel to check how the voltage changes to maximize the output power, so they're always running the panel very close to its sweet spot."
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mlzujb | How did Gandalf the Grey become Gandalf the White? | Other | explainlikeimfive | {
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"Wizards in Middle Earth aren't human, they're angels, called Maiar. When Gandalf died fighting the Balrog, he was reborn with the power of the White, which he used to depose the fallen Saruman and lead the White Council.",
"Within the mythology of Middle Earth (the setting of Lord of the Rings) Gandalf and the other wizards were sort of demi-gods, send to help the goodies (Elves and men) defeat the baddies (orcs). They were sent to Middle Earth in mortal bodies but still had powers etc. When Gandalf was basically finished off by the Balrog his mortal body basically died. But God decided his mission wasn't finished so sent him back as Gandalf the White. It is worth noting that the third book of the Lord of the Rings is much more about Gandalf's rise as a leader than is portrayed in the films.",
"God (Eru) literally just brought him back to life. One of his prevailing themes from before time and creation. Maiar (what Gandalf is) are basically lesser Angels and the Istari (or the Wizards) are special Maiar that are limited to a physical body and are supposed to only work to influence the world for the better. When the Istari Saruman fell to Morgoth’s/Sauron’s influence, Eru revived Gandalf and ‘promoted’ him in order to rebalance the world. The whole story was predetermined by the Ainur and Eru long before Middle Earth existed. In short the answer to how Gandalf went from ‘the Grey’ to ‘the White’ is: Deus ex Machina; God intervened and saved the day.",
"Gandalf was one of the Maiars, Tolekien's equivalent of an angel. He was sent by the Valars (archangels/lesser gods) on a mission to help good guys in the fight against Sauron - of course he couldn't use his full power so he disguised himself as Gandalf the Grey, a happy old man who knows a few magic tricks. Then we have his duel against Balrog where he died. That was the end of his quest, he did what he could and that was supposed to be the end. But being an angel with a mission he couldn't simply die. Eru (God with a capital G) revived him and lifted a bunch of restrictions he had as old Gandalf so he could finish his quest - Thus becoming Gandalf the White, a much stronger, wiser and more powerful version.",
"There are multiple wizzards, akin to angels, and they are characterized by the different colors of their cloaks. Gandalf have a gray cloak and the head of the wizzards, Sauroman, have a pure white cloak. But Sauroman gets corrupted by Sauron and Gandalf dies while fighting the Balrug. So Gandalf is \"sent back\" to Middleearth in a white cloak symbolizing that he is now the leader of the wizzards after the fall of Sauroman."
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mm0dux | What does it mean when objects absorb light? What happens to the light and to the objects? | Chemistry | explainlikeimfive | {
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"Every object is made up of atoms and molecules. Those atoms and molecules have different electronic structures, meaning the electrons inside them sit at different energy levels, different amounts of energy apart. Electrons can absorb photons (light) and move up to a higher energy level with the energy of the photon. So when an abject absorbs light, a photon is basically giving it's energy to one of the electrons inside the object, allowing it to move to a higher energy level and destroying that photon. Objects can only absorb light that corresponds to an exact transition from one energy level to another. Because different materials have different levels, this is why different objects absorb different colours of light and appear to have different colours.",
"The light being absorbed (rather than reflected) transforms into heat. This is why a black car sitting in the sun heats up far quicker than does a white car. The white car reflects away far more light, and thus takes longer to heat up. The black car absorbs the massive amount of light, which transforms into heat, and becomes hotter faster. This is on reason satellites are often coated with reflective material...in order to reduce the heating they would endure from their sun-facing side absorbing light. Instead, most of the light bounces off."
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mm0lrh | What determines the strength of a currency, and how representative is it of the economy strenght? | Economics | explainlikeimfive | {
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"Faith and desire for it. Most currencies aren't backed by anything physical anymore. Even when they were, that backing was still based on peoples desire for the physical item (for example, gold). Basically, a currencies strength is based in peoples desire to possess that currency along with a faith that it will be usable to purchase goods and services (basically the belief that others will want it just as much, if not more than, you do). Currency strength is a direct reflection of economic strength, as economic performance is directly related to the currency. The currency is representative of the economic performance. This is why a country with a poor economy has a currency that is worth less than a country with stronger performance (note: this isn't a straight 1 to 1 comparison as different currencies use different denominations and base values).",
"\"Strength\" here is not a technical term used in economics. The exchange rate of a dollar can go up or down--that's it. The demand for currency is determined by the desire people have to hold that currency. The main reason is in order to make purchases from that country. \\[But sometimes it has to do with paying debts (e.g. China).\\] For example, if I want to buy some manufactured goods from Japan, I will need to convert my USD to Japanese Yen. So I trade some USD for Yen. The more Americans there are like me who want to buy from Japan, the more we will outbid each other for Yen and cause the Japanese to sell us Yen at increasing prices. In this sense, the Yen is \"strengthening\". But that's a terrible term to use here because it suggests this is necessarily a good thing. It is not. Imagine you were the CEO of a Japanese manufacturer. You want to sell your goods. But now Americans are having a harder time buying your goods, because the Yen is getting expensive. So countries will often intentionally seek to keep their currency cheap to encourage exports. The cost of that strategy is it makes it harder for them to buy goods from other countries. So the countries that are famous for this export-driven growth strategy were also famous for struggling to buy imported items, sometimes including basic commodities. Also, when a country is growing especially in its export sector, the currency will likely appreciate *relative to other currencies* (this has nothing to do really with inflation). That is what is usually meant by \"strengthening\". But, again, that's a terrible term."
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mm0tj9 | How in the hell does the 4th dimension work, visual-wise? | If I existed in a 2D world and someone from the 3D world explained to me how their dimension worked, of course I'd have a hard time understanding it. But I feel like I'd be able to at least get a good grip on it eventually since it's not that hard. However, I just saw this video in Youtube which shows how 4D behaves from a 3D perspective and I just do not get it lol. Explain it to me like I'm 5 *please*. TIA! EDIT: So I just realized that 2D would have no idea either how 3D works if a 3D person explained it to me due to visual (and possibly) audio restrictions. Sorry about that. | Physics | explainlikeimfive | {
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"Visually? It doesn't. From a mathematical perspective \"it's not that hard\" to appreciate [4D geometry]( URL_1 ) but it doesn't translate into our physical reality. We can make outlines with 3D figures in plexiglass, say, but they capture one slice at a time. [You can rotate a computer generated 3D model to get a shadow of one, but it's like a cube in 2D space - it doesn't translate well.]( URL_0 ) There is pretty much no way you can draw on a page or watch a Youtube video about a 4D object and get a good representation.",
"\" But I feel like I'd be able to at least get a good grip on it eventually since it's not that hard. \" I think this is quite a leap of logic there, I'm not so sure you'll be able to understand it since the analogy applies to us in the 3rd one trying to understand the 4th",
"There's a great book on the subject that targets your current understanding level called Flatland. It's a quick and easy read, so I'd definitely recommend picking up a copy. Best to use a book so that you control the speed at which it delivers information. There's also a [4D maze game]( URL_0 ) that was written to test if a human mind could learn to visualize 4D space well. The overall finding has been that despite it being possible to become somewhat okay at navigating 4D mazes, your brain never gains the ability to visualize them well. You end up using higher cognitive tricks instead of visualization.",
"I think one could boil it down to how you see a shadow is a two dimensional object from a three dimensional object. We can only see the shadow of the fourth dimensional object.",
"2D-3D: imagine you're standing inside a chalk circle you've drawn on the ground at the middle, the 3rd dimension is whichever direction takes you away from all points of the circle at the same time - in this case up, or down (if you dig). 3D-4D: imagine you're perched in the middle of a spherical bird cage, the fourth dimension is whichever direction takes you away from all sides of the cage at the same time. That... Is as close to visualising it as I can personally get, because I've never experienced that direction, but it's there... In mathematics at least.",
"I was reading “Three Body Problem” and there was a passage there about this topic, which totally broke my mind so I am with you. Basically, something was able to perceive world in 4-D and when asked what do they see they said something like “I can see you from all angles but also inside of you at the same time” and then they explained how a circle when viewed from 2-D perspective is just a line, but shifting to 3-D perspective allows you to see the whole circle along with area inside (not in a transparent way but in a completely mind-altering way) I still cannot imagine what 4-D could look like but it probably is incomprehensible to me.",
"Carl Sagan does a superb job explaining it here: [ URL_0 ]( URL_0 )",
"Yeah, I think your assumption that \"it's not that hard\" is the flaw here. It's almost as difficult for us as 3D creatures to imagine the world of 2D creatures as it is for us to understand the world of 4D creatures. One way to try to visualise this is to imagine \"showing\" q 3D cube to a flatlander. You might do this by slowly passing the cube through their 2D world. It would be a bit like slicing the cube up into thin layers, and letting them look at each shape, then try and get them to imagine the cube. But the layers the see change a lot depending on how you align the cube. Start with the cube flat. As you lower it through their world, they'd see nothing, nothing, nothing, and then suddenly a square would appear. Then this square would stay for a while as you lower the cube, and then it would vanish. So, from their perspective, a cube is just a square. Okay, now you angle it so one edge is along the ground. This time, they'd see a straight line that expands to a rectangle, maybe moves a bit depending on what angle the cube is as, then shrinks back to a line and vanishes. Okay, so a cube is also rectangular. Now the fun one. Suppose you lower it corner first. They'd see a dot, then a triangle, which grows, until suddenly the corners vanish and it becomes a hexagon. Then this becomes a regular hexagon. The it starts to go the other way. Corners appear again and you have a triangle, except this one is facing the other way. Then this shrinks back to a dot. So, flatlander is trying to imagine a shape that's a square, rectangle, triangle, and hexagon all in one. That's not that easy! Besides, did you even know that a cube had a perfect hexagon hidden inside? Trying to visualise 4D is similar. A tesseract (4D version of a cube) that \"falls through 3D\" might look like a cube inside a cube, or a cube beside a cube, in particular orientations and position. But trying to understand how it rotates in 4D is a mental nightmare. We can do it mathematically, but trying to visualise it is nearly impossible.",
"First you have to realize that you're looking at a 2d representation of a 3d representation of a 4d object if you're looking at a flat phone/pc screen 3d looks intuitive on a flat screen because you're used to seeing 3d things represented in 2d",
"Imagine that you have a sphere. A watermelon for example. It's a 3D object. Now imagine that you have a whole shelf of spheres. A supermarket shelf with watermelons. The watermelon in the middle of the shelf is the biggest one, and as you move to the either side, they become smaller and smaller. And then even further away there are empty shells with no watermelons. Well, the shelf is your 4-th dimension, and all the watermelons are one single 4D object, a hyper-sphere. You can pick either one waterlemon, and it will be a 3D 'slice' of the hyper-sphere. They are arranged like this because when you slice a regular 3D sphere, you get smaller circles, then bigger circles in the middle, then smaller circles again, then no circles at all when you reach the edge of your sphere. So similar to this you get smaller spheres, then bigger spheres, then smaller spheres for 4D. That's as good as you get for visualizing it. It's impossible to properly visualize 4-th dimension on the flat 2D screen anyway. Or you can say that the time is your 4-th dimension, and imagine a small watermelon that grows bigger, then gets smaller again. Pretty much what you will see by walking along the shelf with a constant speed and looking at each individual watermelon as the shelf passes by. And if you want to imagine 5-th dimensional hyper-sphere, well, now you have a street of many many supermarkets, each one of them has a shelf with many watermelons. Supermarket at the center has the biggest watermelons, supermarkets farther away all have smaller watermelons, and supermarkets even farther away have no watermelons at all. You get the idea.",
"Think about representing a 3d skyscraper with a bunch of 2d representations, like a floor plan. Lets say a two dimensional person takes an elevator up to the top, and can only perceive the floor they're on. They'd only see one floor, but it would change around them as they ascend.",
"Side question: when did we stop calling Time the \"4th dimension\"?",
"One of my favorite ways of conceptualizing how a fourth dimension works is from Monsters Inc. Check out this JRE clip of Neil Tyson talking about it. URL_0",
"I get that the point of this sub is to actually explain things, but people are already doing that. [This video is a helpful little lesson, complete with an app you can buy.]( URL_0 ) The creator is building a 4D video game that I’ve been anxiously waiting for since like 2014? I don’t even remember when it was first announced."
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mm0v5z | what is so different from console to pc that prevents game from being developed once and published to different platforms? | I keep hearing that consoles nowaday are basically computer, isn't the hardware almost the same? | Technology | explainlikeimfive | {
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"It's like the difference in speaking English and Japanese. Coding languages are different for different platforms. That's why skyrim didn't come out on every platform at the same time but took years to come out on different platforms. They didn't have to start from scratch but they did have to program them to speak different languages of those platforms",
"Consoles are all identical. They have the exact same processor and the exact same graphics chips. This allows developers to build software that can be hyper-specific for that exact computing environment, taking a lot of short cuts and making a lot of assumptions. More general purpose computers don’t have that luxury, there’s a vast array of possible hardware setups that gamers may be using and accounting for them all requires more flexible and less efficient programming. These days developers usually do work with PC in mind as well, but in the past a lot of console exclusive titles took massive hardware-specific shortcuts that left the software extremely difficult to emulate on a PC."
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mm0yk6 | Why can outdoor temperatures fluctuate wildly over short periods of time? | So I vaguely get how seasons work, winter is cold because you're tilting away from the sun etc, but the recent weather in the UK made me curious about more short term fluctuations. It was 20C here last week and today it's dropped down to 4C. Afaik the northern hemisphere hasn't decided it's shy and swung back away from the sun all of a sudden so other things must be driving the sudden drop, but other than *it's kinda windy maybe?* I'm not really sure what those would be? | Physics | explainlikeimfive | {
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"It’s where the wind is coming from basically. Cold air from the Arctic has been getting pulled down to europe which is causing this cold snap. If the air was coming up from the equator it would be warm. The sun is giving out the same amount of energy as last week but it’s trying to warm up a deep freeze.",
"Air is actually a pretty good thermal insulator. This means it takes a while to heat up and cool down. So even though the Earth's tilt is more in position for warmer weather, you still have large masses of cold air in areas. The earth's atmosphere really likes to move too. So on occasion these masses of air will get displaced from their normal spots, such as cold air over the poles."
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mm0zbe | How do we know that photon has no mass? | URL_0 This explanation is way too complex.. can someone ELI5? Thanks! | Physics | explainlikeimfive | {
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"Preempting the comments like \"Well a 5yo isn't going to understand *that*\" by pointing out Rule4 and the fact that OP already used the technical terms \"mass\" and \"photon\". One of the things that happens when we look at things moving at relativistic speeds (say 10% of the speed of light and upwards) is that their effective mass (or momentum) begins to increase. The amount this goes up by is something called the gamma factor, which involves the ratio between the speed of the thing and the speed of light. As the speed gets closer to the speed of light, the gamma factor grows faster and faster. This is why we can ignore it for everyday speeds, the factor is basically 1. But near the speed of light, this number blows up. At the speed of light, this factor would be infinite. So because photons travel at the speed of light, if they had any mass then their effective mass (and so momentum) would be infinite. Given that you can't be blasted in to oblivion by a single photon, this can't be the case. This means their mass must be 0, since 0 times infinity is still 0, sort of... But, the do still have momentum, which is a bit more complicated.",
"r/TorakMcLaren gives a good explanation. A real world indication to use involves Newton's laws. Mainly rule #3. Every action has an equal, but opposite, reaction. This is how rockets and jets produce thrust. They throw gas backwards extremely fast. Because they are throwing the gas backwards, the gas is throwing the rocket/jet forwards. Because gas has mass. Now, lets use the example of a flashlight. It emits a lot of light in a specific direction. If the photons had mass, this would result in a net force pushing the flashlight in the opposite direction. Using the information given by r/TorakMcLaren , if photons had any mass, this would not only obliterate anything in front of the flashlight, it would also launch the flashlight backwards killing you and a very large number of other people."
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mm1bua | Why do rechargeable batteries lose capacity over time? | Technology | explainlikeimfive | {
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"Rechargeable batteries relies on chemical reactions to provide electricity, and the opposite chemical reaction occurs when you provide electricity **to** the battery. That's how they store the energy. Because of lots of factors (temperature, impurities, age and cycles, degradation of chemical compounds, physical degradation of the materials making the cell, etc) over time that reaction becomes more difficult, or there is less materials available for it to happen, and the result is you see a reduction in battery capacity.",
"* Rechargeable batteries produce electricity through a chemical reaction. * They also store energy by reversing that chemical reaction. * But there are also by products of both the forward and reverse version of the reaction. * Those byproducts are basically junk that take up room on the internal terminals on the battery. * They block electrons from flowing through the terminals. * Eventually too much junk builds up and not enough electrons can get through fast enough to maintain the voltage needed for whatever device your are powering."
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mm269n | Ultraviolet radiation falls inbetween x-ray and visible light in terms of wave length. How is it that we can see ”artifical” UV in e.g lamps? | I stunpled upon a wave length figure explaining different radiation and had this thought which I couldn’t find an answer to on google. Maybe my googling skills are more inferior than I previously percieved. | Physics | explainlikeimfive | {
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"UV lights usually don’t *only* produce UV - there’s also a lot of light near the higher energy end of the visible spectrum. This tends to make them appear blueish. Sources that only produce UV do exist, but they’re often more expensive. They can also be dangerous because it’s not always clear that they’re on.",
"UV lamps don't create a sharp peak, but a very broad spectrum. The majority of it is in the UV wavelength area, but a small portion of the peak is still in the visible. Think of it like a mountain that technically belongs to the neighboring county. If it's very narrow, you won't really notice it from yours. But if it's broad, you will have hilly terrain leading up to it already in your county, even though the peak isn't there."
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mm2bbr | (HACKING) How are bruteforce, dictionnary and hybrid attack still a thing when a server can just limit the number of attempt per seconds ? | Technology | explainlikeimfive | {
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"Normally you don't attack the server, you manage to get a leaked copy of the database (which holds the encrypted/hashed passwords) and brute force that. Same goes with winrar - you don't try to break the encryption using winrar, you write your own program that tries to decrypt the rar password without using winrar itself.",
"Here's what happens. Someone runs a website called funnycatpics.whatever. They let you log in, with your email as the username, and a password. You just use the same password you use for everything. One day, funnycatpics.whatever gets hacked and their database gets leaked. It contains a lot of email addresses and password hash combinations. I pay someone money for a copy of that database. Now I have emails and password hashes. I start using a series of attacks to reverse the hash of the passwords and get the original passwords. I now have a list of email addresses and passwords. I start trying them on other websites. Lo and behold, the password also logs you into the hotmail account you were using, and from there I can get anywhere. It might also get into your online banking, or into many other accounts that are a lot more damaging from being exposed than funnycatpics.whatever.",
"Just because something can be done, doesn't mean it *is* done. Some people write bad websites that don't have this kind of limitation."
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mm2oiu | -How does the atmosphere stop the oxygen from leaking and spreading out into space? | Physics | explainlikeimfive | {
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"The atmosphere doesn't. Earth's gravity is what makes sure that most of the oxygen (and the ither gases) is concentrated fairly close to the surface if our Planet",
"Gravity keeps them confined to a thin layer near the Earth. The molecules would have to reach a speed of about 11 km/s to escape Earth's gravity. Any less and they will fall back sooner or later. It's called Escape Velocity and it's true for any object, gas molecule or spacecraft like the Voyager probes. The typical speeds of oxygen or nitrogen molecules at 20°C is only about one twentieth of that value, they are even slower in the cold upper air. Occssionally, a fortuitous combination of collisions could allow a single molecule to gain that sort of speed but note going to be rare. Lighter molecules like hydrogen or helium can escape though.",
"I blame [educational graphics like this]( URL_0 ) for making people think Earth has this huge atmosphere layer, and how could gravity possible hold it in at that distance? The atmosphere is a [very thin shell]( URL_1 ) around the planet. Beyond that the atmosphere gets so thin it starts blending in with space. Our gravity can only hold this thick of an atmosphere very close to it.",
"So some of the previous answers are close, but not complete. The earth is constantly streaming atmosphere into space. Part of the issue in this topic is defining exactly WHERE the earths atmosphere ends. The generally accepted definition for \"space\" is 100km. The problem is that our atmosphere doesn't just stop there, it extends above that. The International Space Station orbits at approx. 400 km. It has to periodically reboost its orbit because it is slowed by atmospheric drag. Yes, atmosphere at 4x the height space starts. Basically, the atmosphere isn't like the ocean, it doesn't just stop at a definite point. It fades out. So eventually there is a point where the \"atmosphere\" becomes indistinguishable from solar wind. Check out this wiki article for some of the different methods atmospheric loss occurs: [ URL_1 ]( URL_0 ) Edit: To add, the amount of loss is overall very small. A few kilograms per second. Current approx. total mass of the atmosphere is 5,150,000,000,000,000,000 kilograms. So we have plenty of time."
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mm2trv | Do small people wear out their shoes faster because they take more steps or do large people because they weigh more? | Other | explainlikeimfive | {
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"Larger people wear out shoes faster than smaller people, regardless of shoe size. Friction is independent of surface area when examining the wear and tear on shoe soles. The size doesn't matter as much as the weight of the person wearing them. For other items internally, like the cushion, or the stitching, those factor in the size of the person's foot. A heavier person on a small foot will wear out the cushion more quickly because their heel applies more force per area than a person with a larger foot of the same body weight. And the stitching has the same tensile strength regardless of the size of shoe or weight of person, so whichever combination provides the highest tension on the stitches will damage them most quickly. I'd say heavier people wear out shoes more quickly than smaller feet."
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mm2wg3 | Why do you start seeing a word/phrase/expression everywhere right after you learn what it means?? | Other | explainlikeimfive | {
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"Might explain it **Frequency illusion**, also known as the **Baader–Meinhof phenomenon**, is a [cognitive]( URL_5 ) bias in which, after noticing something for the first time, there is a tendency to notice it more often, leading someone to believe that it has a high frequency (a form of [selection bias]( URL_4 )).[\\[1\\]]( URL_7 #cite_note-zwicky-1)[\\[2\\]]( URL_0 )[\\[3\\]]( URL_2 ) It occurs when increased awareness of something creates the illusion that it is appearing more often.[\\[4\\]]( URL_1 ) Put plainly, the frequency illusion is when \"a concept or thing you just found out about suddenly seems to crop up everywhere.\"[\\[5\\]]( URL_6 ) [ URL_3 ]( URL_7 )",
"It’s called the Baader-Meinhof effect, or frequency illusion. It’s when being made aware of something makes you notice it more, so you think it’s more common. But you’re just noticing it more.",
"If I were to explain from experience, it's basically this. Your brain is good at blocking what you don't know out, allowing you to focus on what you do. When you learn something new, your brain doesn't block that out anymore, so it seems that it exists everywhere.",
"I think it could be said that the same effect applies while learning new languages: Without a good vocabulary, most of what you hear in other languages might sound like gibberish as you can not discern one word from the other, but when you hear a word you know you can single it out from what is being said."
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mm3p3v | - How can you be addicted to something and unable to stop? | I am unsure of how an addiction works mentally and what drives those with addictions. I understand on a small scale biological way (i.e. caffeine withdrawl headaches) but I have no understanding on why dropping/ controlling an addiction is difficult and sometimes incurs relapses? | Other | explainlikeimfive | {
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"The drug/substance causes certain physical responses and releases of chemicals in your brain that your brain then develops a dependence on - it needs that chemical more to \"feel normal\", and the only way to get it is to consume that drug/substance again. It's a dumb example but imagine you have a canal in your brain that water flows through normally and you function just fine without any chemicals or substances. And then you start drinking alcohol - well that alcohol starts carving out a second canal in your brain. Your brain starts wanting you to open the tap to keep that beer river flowing because it feels \"normal\" and makes your body function. A person without alcohol dependence doesn't have that secondary beer canal but a person with alcohol dependence does.",
"Lots of people are putting relatively good information into this thread, but it's important to stress that addiction is complex and not completely understood. Chemical dependency and withdrawal symptoms seem to be important for addictions to substances like opiates, but these drugs are often used by people who do not become addicted. Environmental factors such as social networks and life situations are clearly important. Genetics and personal biology also surely play a role along with life experiences. Also, it's worth pointing out that it would be difficult if not impossible to design ethical experiments that would be helpful in teasing out the influences of these various factors, so you're left with observational studies. Furthermore, even defining addiction from a diagnostic and scientific standpoint is contentious.",
"Downers are addictive, because they make you not mind the things you hate. Uppers are addictive because they give you the energy to do the things you love. Psychedelics are addictive because they give you a mind when you don't have one.",
"You can get psychologically addicted to almost anything. The key is that it makes you feel good (or at least less bad). You genuinely *like* the way that it makes you feel. With psychological addiction, it's not a case of being unable to stop. It's more that you don't really *want* to stop, even though you know that you should. You simply enjoy the thing you are addicted to more than you like the idea that you'll have a better life in the future. You know that if you stop, your life will probably improve in some ways. But you also know that you can get instant gratification from the thing you are addicted to. It's very easy to choose the thing that immediately feels good over a long-term quality of life improvement. Physical addiction just adds to all that. If you do stop, you start to feel bad. In some cases, very very bad. So on one hand, you've got a course of action that makes you feel like crap but hopefully you'll have a better life down the road. Or you have a choice to feel good right away. That can be a hard trap to escape from.",
"Someone else will explain the physical aspect better than I; so I will tackle the psychological: You don't become addicted to drugs for no reason. People rarely get addicted just because \"it's fun.\" People who use drugs regularly enough to become addicted are consistently attempting to treat underlying disorder or pain. Asking a severely depressed, mentally ill, emotionally damaged or physically infirm person to stop using drugs is like asking a healthy person to stop being happy.",
"The best way I can put it is this: You eat food. Your body realizes it likes food. But then you don't get food for a little bit and you get hungry. This is your body telling you it needs food. The same happens for addicts. You add a new substance to your body. Your body realizes it likes this substance. But then you don't get the substance for a little bit and you get hungry for that substance. This is your body telling you that it needs/wants it. You know how people can get hangry or shaky because they haven't eaten? It's similar to those in addiction who are being deprived of their drug of choice. In order to fix this new \"hunger\" deprivation, people use again to fix it. And it becomes a cycle. I hope this helps?"
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mm54hr | What are colors on an atomic level? What makes a rose red, a tree brown, and gold yellow? | Physics | explainlikeimfive | {
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"Photons or light waves can have a variety of energy levels, from very low (like those emitted by radio antennas) to medium (the light you can see) to high (the x-rays or gamma rays that can give you cancer). When light hits a surface, it's hitting the electrons of the atoms in that surface, and either being absorbed by the electrons or bounced back off of them. There can be other effects, like how hot surfaces actively emit light (like red-hot iron), or some surfaces absorb light at one color and emit it in another immediately (fluorescence) or over time (phosphorescence). White light contains all the visible colors of light. When white light strikes an object and the object appears to have a particular color, that means that most of the light hitting it was absorbed, but some colors of light were reflected or emitted from it.",
"What we see as color is all the light that wasn't absorbed by whatever it bounced off of. A rose is red because the matter that makes up the rose absorbs all the light except red. A black road is black because it's absorbing all the color from the light",
"Think of light as a mixed bowl of candy. This bowl has jolly ranchers, it has starburst, it has packets of MnMs, it has mini snickers, and so on. These candies are the colors in our light - sunlight (and other white light) has all of these colors already in it. Then you give this mixed bowl of candy to a classroom of kids. You know they like every candy except snickers, and sure enough, after that bowl of candy makes contact with the class, they eat everything in the bowl, except the snickers. After the bowl leaves the classroom we only have one candy left, our snickers, and everything else had been absorbed by the class to fuel their youthful energy. Same thing with light. After hitting a material, most of the possible colors get absorbed, their energy staying in the material (usually as heat). All you get to see if the light enters your eyes afterwards - if you look at the bowl after the class got to eat - is the color that's left. You only get to see the snickers they left behind.",
"I would like to stress something: there are some \"real\" colors and some \"non real\" ones, basically made up from our brain. Brown is one of them. It actually does not exists. There is no difference from brown and orange. It all depends on what our brain sees surrounding it. For all of those that missed some point here it is a good [resource]( URL_0 ) to explain what I meant.",
"(Talking about chemical color only.) Roughly speaking, a given molecule has a number of different states that the electrons around that molecule can be in, each with a certain amount of energy, and a certain number of electrons to partially fill those states. Naturally, the electrons will almost always be found in the lowest energy states, but if light arrives of the right energy range it can temporarily bump an electron up to a higher energy state. This is what light absorption, so color, is. Normally the difference in energy between the occupied and unoccupied states is very high, like ultraviolet level or higher, so most small molecules appear colorless. Visible color comes from an exceptionally small energy gap. For example, transition metal ions (say, copper or iron) often have both filled and unfilled \"d orbitals\". If the ion was just floating out in space the different d orbitals would be the same energy, and so colorless. But in solution the various molecules surrounding the metal atom break the symmetry to make some orbitals slightly higher energy than others. Hence solutions of metals in various solvents tend to have bright colors. Similarly, if you look at a drawing of a colored organic compound (search for pictures of dye molecules), you will see an extended sequence of alternating double bonds. You should interpret this as giving room for complicated electronic behavior (some electron states get spread out over the whole molecule) that can allow for closely spaced energy states. (Actually telling what color, if any, the molecule will be is still serious chemistry.) Many pigments, like chlorophyll or heme, combine a transition metal core with a surrounding system of double bonds, for extra amusement.",
"Colour is the result of light of specific frequencies hitting receptors in your eye. There are 2 main types: spectral and non-spectral colour. When light hits an object, some frequencies of light are absorbed and some are reflected. Each object reflects different bands of frequencies. The reflected frequencies are the spectral colours we perceive. Our eyes only have 3 colour receptors though, red, green, and blue. For the red receptors, a particular frequency of light causes maximum signal, and the frequencies surrounding that optima may still cause a weaker signal. The same is true for the green and blue receptors. Each receptor is tuned to specific wavelengths of light. Finally, non-spectral colours don't actually correspond to a frequency. For example, there is no \"purple\" frequency, instead it's a what we perceive when we see red and blue frequencies simultaneously.",
"Since people seem to suck at explaining this, I'll give it a try. Even though it's a bit problematic and incorrect think of the model of an atom you were taught about. You have the center and then electrons which can orbit at different levels. Each level of orbiting electron needs a certain amount of energy to \"jump\" up to the next level. So when you have full spectrum light hit an object the electrons will absorb the wavelengths of light needed to make the jump and reflect the wavelengths it doesn't need. Eventually these \"excited\" electrons drop down by releasing the energy they absorbed which allows it to happen constantly and why colours stay consistent. This emitted energy doesn't provide colour to an object cuz it either gets drowned out by the reflected light, or cuz it happens in stages and emites low energy photons which we can't even see. This is also why an object that is a bright colour looks a lot darker than normal when in a light that isn't full spectrum, like infra red, or black light, cuz there isn't the right wavelength for the electrons to absorb. Also fun fact: this isn't really how blue works in nature. Not a lot of things are naturally blue, and most things that look blue do so for a completely different reason than explained here.",
"Colors on an atomic level are produced by electronic transitions. When light falls upon an object, the electrons of the atoms of the illuminated material absorb certain wavelengths and reflect the others. What wavelength is absorbed depends on the difference in electron energy levels of that specific atom/material. Now if the material absorbs all the wavelengths, means that the object would appear black. You can test this by shining blue light on a red rose. As a red rose reflects back the red portion of white light, when only blue light falls on it, it gets absorbed and nothing is reflected back, thus making it appear black. This is the reason why fashion shows do not have any colorful spotlights like in dance halls, bars. Just bright white lights. On the other hand, if a material reflects all the wavelengths, the object would appear white. You can test this also by shining colored lights on a white car for example. If you shine blue, the illuminated portion would appear blue. If you shine red light there, it would appear red. Because it just reflects whatever wavelength you throw at it. For us to see color, the important part is that the reflected light from the object should contain wavelengths from the visible spectrum.",
"Colours don't exist on an atomic level. They are made up by our brains when light hits our eyes. Light can have different wavelengths and different combinations of these wavelengths get interpreted as different \"*colours*\" by our eyes. Just like music doesn't exist in nature. Sound exists, but music only exists within the human mind.",
"There are actually different ways of producing color. It can structural or atomic. I think gold's color is atomic. In that case the atoms can absorb certain wavelength which cause an electron to jump an energy level, then to return to its normal energy level it releases a photon at a specific frequency that we can see. I do not understand how structural color works.",
"To this effect, what are atoms/matter actually \"made of?\" Like elements are formed by different combinations of atoms, and chemicals different formations of elements, but what is the actual \"stuff\" a proton or electron or quark, etc, are \"made of?\"",
"In reality colors don't exist like we think they do. The colors that we see are just what our brain makes up to interpret different wavelengths of light. When you see red, someone else could be seeing a completely different looking color, but both of your brains have always interpreted that color looking that way. If you asked them what color they see they'd say red, but you really have know idea if you're seeing the same thing.",
"Color is what your brain interprets different wavelengths of light. An atom giving off a color is merely the wavelength of light it emits.",
"Oooh, a question I can answer! So, what we see as white or colourless light is actually a combination of all the colours of light. (Fun bonus fact: that's how rainbows work the rainwater fractures and splits the light apart so we can see each colour individually rather than one colour: white) Now, on the molecular level, everything is composed of atoms, which are connected by pairs of electrons. These electron pairs can have different amounts of energy, but mostly they hang aroung like a bunch of depressed/stoned teenagers. If someone's made pot brownies, they're game! And for electrons these exciting things are usually provoked by radiation. Much like light. The energy these electrons care for is a consequence of how they're paired up, but usually they only care about radiation that *isn't* visible light. When electrons do care about visible light energy however, they partake. To go back to the pot brownies analogy: they'll have some, and by the time they leave you can see by the empty platter that they've been there. Heck if you're really clever you might be able to identify which stoner teen was over by knowing if they only like corner pieces, edge pieces or middle pieces. Similarly if they care about visible light, they'll have *some* and *leave the rest* of the visible light which remains for us to see. That help? Please hit me up with questions, I'm seriously considering a carreer in education."
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mm6up5 | How exactly does soap clean our skin? | Chemistry | explainlikeimfive | {
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"Water is good at cleaning some things because those things interact with the water more favorably than they do your skin. When water washes over your skin that stuff binds to the water and leaves with it. However, there are other things that interact with your skin more favorably than water. these won't, for the most part, leave just because some water comes by. Soap consists of molecules that have two very different ends. One end interacts well with water while the other end interacts well with stuff that doesn't interact well with water. This means it can basically act like a chain connecting the water rushing by to this stuff that water normally doesn't interact with too much.",
"Soap does two things 1) soap decreases something called \"surface tension\", which essentially means it makes things break apart and become slippery. So any dirt, microorganisms, chemicals, etc, on our hands (With good washing) will wash off and leave our hands and go down the drain. 2) soap chemically damages the cell walls of microorganisms helping to deactivate them even if they aren't 100% removed from your skin during washing."
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mm70qc | Why is it that when you chew gum on flights it helps with the changing of altitude pressure in your head? | Biology | explainlikeimfive | {
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"Your inner ear and outer ear are separated by a thin membrain. The air pressure in youre inner ear is made homogeneous with the air pressure in your outer ear by a duct when you chew, yawn, or work your jaw in a similar manner to when you do those things. Thats how I remember it from anatomy class anyway. That was a while ago",
"The eustachian tube is a tiny tube that helps balance the pressure in your inner ear. Effectively, it's the only way air can get in or out of the part of your ear behind the eardrum. It goes from your inner ear to the back of your throat, upwards behind your nose. Chewing and yawning, and jaw movements in general, help flex the eustachian tube to allow air to move through it, think of it kind of like coaxing toothpaste out of a tube. This balances the inner and out ear pressure, giving you some relief."
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mm74bg | What do today's groundbreaking results of the Muon g-2 study actually mean for (particle physics) science? | Physics | explainlikeimfive | {
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"We don't know yet. If the results hold, and are repeatable, then it could mean that revision to the Standard Model of Particle Physics (current best model of particle physics) might be needed, and it gives a place to look more closely at where it breaks. Right now, the only places where we know it to be incomplete is in black holes, which we can't readily test, so any place where we can improve our models will be exciting."
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mm7nsa | What is the "science" behind people being attracted to anime characters? | Biology | explainlikeimfive | {
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"There is a phenomenon called 'superstimulation' that might be partly responsible. At least in a biological sense. Superstimulation is an overexaggeration of certain qualities that we, as humans, are hardwired to find appealing. This exaggeration is pushed to extreme and often impossible limits. Certain things like hip size or body ratio (indicating peak fertility) and especially eye size can play a part in this. The mannerisms of these characters can help to emphasise a sexually suggestive nature and work in tandem with extremely noticeable body proportions. Hermit crabs (the ones that use shells for houses and switch them up) often prefer soda can to natural sea shells simply because the drinks cans trigger absolutely everything they find ideal in a new home. Despite the cans offering less benefits than shells. Similar things can happen across the animal kingdom often with terrible consequences in that the animal will perish due to being tricked by itself. Additionally, advertising agencies and gambling companies use the exact same tricks to hook you to products. Many more factors are at play here as human psycology and sexual attraction is a gigantic and complex issue. But this be a contributing factor explainable in a more scientific way.",
"It's not like humans' sexual instincts are wired to know every single detail about what a human appears to be in order to be attracted. We're pattern recognizing creatures. If a fictional character fits the pattern that is a human closely enough, attraction, empathy, and such can be triggered. Our pattern recognition runs on the principle of \"close enough.\" This is why pareidolia exists.",
"There's no science it's just normal attraction. Just like you get a celebrity crush you get an anime girl crush.",
"The character might have a physical representation that you like or that your brain can work around (in case for furry/alien characters). Said character might also have a kind of personality that you find endearing or attractive. Mix in a bit of humanization (the exact same thing that we do to our pets) and you have a brain that can find a way to find something attractive."
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mm7qjx | | How does a computer calculate sin/cos/tan? | Mathematics | explainlikeimfive | {
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"They either use a look up table, or some sort of easily computable approximation like [CORDIC]( URL_0 ). These don't give exact results, but computers have limited precision, so results only need to be correct up to the available precision.",
"If you know calculus, one pretty simple option is just to use its Taylor series (sin x = x - x^(3)/3! + x^(5)/5! - x^(7)/7! + ... + (-1)^(n)x^(2n + 1)/(2n+1)!, and cos x = 1 - x^(2)/2! + x^(4)/4! - x^(6)/6! + ... + (-1)^(n)x^(2n)/(2n)!, [here you can see the sin graph]( URL_0 )). You only need a few Taylor series terms to get a good approximation for all values between -pi and pi, and any trig student knows you can just subtract or add by 2pi until you have a value around this to put into your sin or cos. CORDIC was mentioned by the other poster and is also pretty cool, a rough explanation for the motivation behind that method is that they hardcode sin and cos values for powers of two, then just use the angle addition formulas from your trig class to add up to whatever angle you wish. CORDIC is used less these days from my understanding though, CORDIC is cool because it can be optimized to not use multiplication and division operations, which once were more expensive operations to implement in computer hardware, but from my understanding Taylor series approximates better with less operations than CORDIC, even if the Taylor series requires more expensive multiplications to do, thus cordic is used less these days."
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mm8q82 | My wife & I have consistently opposite temperatures in the same room/environment. I could understand if it was just like "Oh, she's always colder than me" or whatever. But no, when I'm roasting, she complains that it's too cold; when I'm absolutely freezing, she'll ask to turn the heat down. | So yeah, how does this work, physiologically? | Biology | explainlikeimfive | {
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"You are two different people, with two different body types, with two different thermal characteristics. Each of your bodies handles maintaining thermal stasis differently. Its entirely possible one of you has a naturally higher capillary blood flow in your skin. This results in different perceived comfort zones for external temperatures. One of you could have a slightly higher resting metabolic rate. This generates more heat, so you prefer a cooler room to help remove the heat quicker. Multiple possible reasons.",
"Are you sure she's not just trying to finish you off?",
"Is she menopausal or premenopausal? That would explain a lot."
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mm9ki4 | Why is it easier to detect air currents when our skin is damp or wet? | Physics | explainlikeimfive | {
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"text": [
"Because the liquid on your skin evaporates faster in a breeze. This evaporation pulls heat out of your skin, and the result is you get cold where the air is moving."
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mm9vkd | What are Muons? | Physics | explainlikeimfive | {
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"Muons are somewhat like heavier versions of the electron, both electrons and muons are a type of fundamental particle called a lepton. Just like electrons Muons have a negative charge and can interact via the electromagnetic or weak forces, but they have a much higher rest mass than electrons, about 200 times greater. This higher mass means they are unstable, a muon on its own will quickly decay into an electron with a half life of around 2 microseconds. We detect muons in particle accelerators and also as showers of particles resulting from cosmic rays hitting the atmosphere. There is also an even heavier lepton called a Tau with a mass around 3000x that of an electron, this much higher mass makes them even more unstable and so they decay with a lifetime of 2.9x10\\^13 seconds, we can only really detect tau particles in very energetic particle accelerators.",
"A muon is one of 6 types of fundamental particles that are collectively called \"leptons.\" It's a fundamental particle that can be described as being \"like an electron, except 207 times heavier.\" Of course, just saying it like that can be very misleading -- because a key fact about muons is their very short average lifetime of only a couple millionths of a second (measured in their rest frame). Indeed, they're unstable and will \"decay\" to yield electrons as part of the process. Crucially for us, electrons are stable particles, because the universe's conservation laws won't let them \"decay\" into lighter particles. So if you want to calculate the fundamental forces acting on a muon, you can say \"it's like a kind of heavy electron\", but if you're considering it in daily life, you have to say \"its short lifetime makes it quite unlike an electron.\""
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mma2t5 | Why is colonel pronounce kernel? | Other | explainlikeimfive | {
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"it is the result of several countries stealing the word colonello from the italian language, meaning a military official. the french stole it and it became something like coronel, because 2 l sounds back to back is difficult to annunciate in the french dialect. then the spanish also stole both versions and straight up turned it into the version you posted \"kernel\" finally america stole the spelling of the word from the french and the pronunciation from the spanish resulting in \"colonel\" being pronounced \"kernel\"",
"there’s a phenomenon in linguistics called “dissimilation”, where similar sounds next to each other are made more different to make them easier to hear. this is the opposite of “assimilation”, where sounds next to each other are made more similar to make them easier to say. in english, dissimilation can be seen in the words “february”, where the two R sounds that close together can be hard to pronounce, so most people say something like “febyuary”; or how the two nasal sounds in “government” can be hard to pronounce so most people just say “goverment”. this happens in many languages; not just english, so oftentimes when a word is borrowed from one language to another, it changes to make it more easily pronounceable for the speakers of the language it’s borrowed into. as another comment states, “colonello”, the original italian word, was borrowed into several other european languages. all of these influence english in different ways, where a language might influence the spelling but another the pronunciation. this is common, and sometimes the spelling and pronunciation doesn’t line up correctly, as with “colonel” or even “lieutenant”."
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mma38z | How does our brain create interests/hobbies and is there any advantages for humans having them? | I just want to know the process of the brain selecting a particular thing and making it an interest/hobby and the reason for doing so. | Biology | explainlikeimfive | {
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"The term you’ll want to look into is “motivational salience.” Basically, when we do something, based on our experience of it, we may consider it to be more rewarding (has an incentive quality) or punishing (has an aversive quality.) And then based on our continuing interactions with that object, we can reinforce if it is rewarding or punishing to interact with it. Our relationship to working with it over time can be considered a “hobby” or “interest” in the simplest understanding of those terms. Now, based on how rewarding or punishing we find an activity, our brains are wired to have us consider how much time and energy we want to devote to doing that activity, which when it continues for long enough periods of time, would fit a definition of a hobby or interest. The advantage of this is that we can be conditioned to be inherently motivated (motivated by our own processes and not by external reward such as money or the praise of others) and still want to do something, just because it catches our interest. Even if such an interest started originally due to external reward. This kind of reward system can be very powerful, and can foster behaviors that impact you over your entire life (e.g. pursuing a career, taking up a study, amassing a collection, amongst other goals and preoccupations.)"
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mma4xa | How to Recruit Moderators? | Hi Everyone, ELI5 is looking for new moderators. There is no pay. You can expect people to be rude to you. People will blame you personally for actions you take that are entirely in line with the subreddit rules. There is no personal glory, and you can't use your position to cross promote yourself, your personal projects, or your other subreddits. The only redeeming quality is that get help the community out, as a whole. If that sounds like a position you're interested in, we'd love to hear from you. Fill out this form: [ URL_0 ]( URL_2 ) If you have any questions before you apply, please put them in this thread. We don't know what kind of demand we'll have, so we can't promise an individual response for every applicant. I'll also use this thread as a brief opportunity to plug [/r/ideasforeli5]( URL_1 ), where any ideas for eli5 are presented directly to the moderators and for public discussion. (Obviously Rule 3 doesn't apply in this thread, the only real rules are try to stay mostly on topic and Rule 1 is never waived, so be nice!) Thank you | Other | explainlikeimfive | {
"a_id": [
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"text": [
"One can recruit moderators by stickying a post to their subreddit asking for members to fill out a form that acts as an application. Hope this helps!",
"Might as well become a meter reader instead. At least you get paid for that.",
"I hope there's new mods coming. I left this sub because my answers were not dissertations when dissertations were not needed. Sometimes a full explanation only requires a sentence or two. Good luck!",
"ELI5: Why would anyone want to be a moderator? Does it give them a sense of purpose in their otherwise meaningless lives?"
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mmamar | What is equity and how is it different from equality? | I am in high school and I need to write an essay on whether or not the US justice system provides equity. However I can’t seem to understand any of it . If you could provide examples or an explanation that a teenager could understand, that would be wonderful! :) Thank you !! | Economics | explainlikeimfive | {
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"Equality is everybody gets the same, whether it's the right amount, too much, or not enough. Equality might be something like everybody gets fined $100 for speeding. But for the unemployed person racing to get to an interview on time, $100 is a HUGE financial burden. For a middle class person, it's not fun to lose $100 but not life changing. And for a millionaire, it's not even pocket change so they'll drive fast for fun and view tickets as an expense like filling up with gas is. So a system looking for equity might charge people a % of income, ie. an unemployed person getting unemployment might pay $10, a middle class person pays $100, and a wealthy person pays $10,000. Then their financial burden is more consistent relative to wealth.",
"Equality is everyone gets the same treatment. Equity is everyone gets the treatment tailored specifically to their needs to achieve the same results or outcome. As others have mentioned, there's a handful of useful illustrations. Here's [my favorite]( URL_0 ) example (comes from economics). In the argument between equity and equality, you have to examine all sides of the argument and the system within which it's being argued. In large scale systems I tend to believe equality is superior to equity from a pragmatic perspective. It takes lots of attention to detail, power, and control to administer equity on a large scale. Economic equity is a bad thing. College admission equity is a bad thing. Income equity is a bad thing. In those cases equality is a far superior standard, and easier to implement. But in the examples of distributing bandaids to four kids like u/DevlynBlaise said, obviously equity is the right approach. Administering equity in this case provides the best care. Healthcare in general is an equity industry. You're given treatment based on your individual needs. It lacks equality in that those with more money can afford better doctors and pricier procedures and medications. There's no clear cut answer for whether equity or equality is superior. It's case-specific and depends a lot on how you define the favorable outcomes. u/WRSaunders mentioned things like equality in the Justice system by having the government win all the time. That's an unfavorable outcome and a great example of when equality is a bad thing. For the specific example you're asking about, the justice system, we generally have both equity and equality. True in life, and the justice system, the more money you have the more options you have. Our legal system imposes a much higher burden on the poor. However, it's often flooded with the poor to begin with. There's a correlation between annual income and criminal behavior. I'll caveat that by saying criminal behavior has many contributing factors and most statistical social science on the topic is difficult to draw clear conclusions from along a single dimension like \"income\"; however, people who hold steady jobs and make more money find themselves committing crime less often than folks in more desperate or less stable situations.",
"My understanding is - Equity means everyone is given what they *need* so that we are equal. Example: 4 kindergartners are given bandages when they get hurt, with the size changing based on the wound size. Each given what they needed, each had been cared for. Equality means everyone is treated the same, even if they need more or less. Example: 4 kindergartners are hurt, every child in the class is given the same sized bandage, even if it's not needed or too small."
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mmaqia | Why is everything in 3D modeling triangles? | Downloaded blender looking to try something new, gain a new skill. Fired up some YouTube tutorials, after a while I’m just left wondering why is literally everything made of triangles? I get that you can make other shapes out of all triangles, but why use two triangles when a rectangle would work just as well? | Technology | explainlikeimfive | {
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"You already said it yourself, every shape can be made out of triangles. Most modeling is done using meshing, which is a large series of interconnected nodes (usually triangular meshing). I think a good way of picturing this is if you had a rectangle, and you needed to know the distance between one corner of the rectangle to the other for interaction purposes, there's only two ways of calculating this. The first is vector addition (unnecessarily long and arduous), and the second is triangulation which is much faster and more efficient.",
"Three points is the simplest way to define a flat plane in 3-dimensional space. This allows 3d models to be made, by defining various combinations of triangles. For solids, the interior volume is coded as ‘filled’, rather than empty. This giant assembly of triangles makes a ‘wire mesh’ that defines the geometry of the solid body.",
"Former game developer here, > why use two triangles when a rectangle would work just as well? And what is a rectangle, but two triangles? Triangles are the smallest geometric unit possible for a render engine. It simplifies matters that you have few foundational parts that you build everything upon. There are few advantages to using different fundamental geometries. There are volumetric geometries and renderers out there, they're principally used in engineering and 3D printing/CNC milling and machining."
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mmb93i | Why do otherwis reputable news agencies choose to host fake/misleading clickbait articles on their sites? | Technology | explainlikeimfive | {
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"text": [
"Because it makes them money. They are corporations, and corporations exist for a solitary purpose: make the stockholders money *NOW*."
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mmcuwd | Who decided that this side of the world map is the top and it should be the north pole? | Physics | explainlikeimfive | {
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"16th century Europeans, probably because they used the North Star to navigate as it is the only fixed star in the northern hemisphere.",
"There is a fairly neat article on this [by the BBC]( URL_2 ). The simple answer is Gerardus Mercator in his [1569 map]( URL_0 ). His method of projecting the surface of a sphere onto a flat space fixed lines of longitude (so North-South lines) as those were particularly important for long-distance sailing. Having North at the top (and South at the bottom) is important for this, but makes the map really inaccurate at these edges; but that's not a problem when no one wants to travel to the poles. Before that maps used all sorts of different directions. Earlier Christian maps tended to have East at the top (pointing towards Jerusalem), and the verb \"to orient\" (as in orienteering, disorientate etc.) comes from the idea of orienting maps so that the Orient (where the Sun rises, i.e. the East) was that the top (\"orior\" being the Latin to do with rising). Other maps picked all sorts of different directions for the top, although the older they were the less reliable. So [this map]( URL_1 ) (the Hereford mappa mundi from ~1300) has Jerusalem in the middle, so East at the top, but the map is... kind of wrong; the Mediterranean is L-shaped as it turns into the Black Sea, and Great Britain is East of parts of Scandinavia. [Here is another fun East-is-up map]( URL_3 ), a recreation of the Ebstorfer World Map from the 13th century. Again, precise layout over long distances is pretty terrible, but wouldn't be that important to travellers (particularly without aeroplanes), with more importance on how to get from city to city.",
"Short answer? European cartographers who used compass and sextant to keep there bearings, however there are plenty of maps that don't put north on top. Generally they are small scale town, city, region maps, but there are of course [larger maps]( URL_0 ) as well. In some middle eastern areas it is common to use maps with east at the top.",
"90% of the population lives on the North Hemisphere, and all the earliest maps were designed by those people. Maps currently in use are all more or less descendants of European early Modern period maps",
"A magnetic compass points north-south which makes those the most reasonable possible orientations for maps intended to be navigated using a magnetic compass. Also, as someone pointed out, the north star, which appears to be one of the only stars visible in the northern hemisphere that doesn't change orientation constantly because of the earth's rotation. the earth is rotating along its north-south axis, and that axis wobbles in relation to the sun, which means that even sunrise and sunset change constantly... so in the northern hemisphere, the easier direction to reliably find is north. The reason it's oriented north instead of south is probably just that europe is in the northern hemisphere, and europeans are the ones who made those particular maps"
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mmczzo | Explain the rules of thermodynamics, but in a way that people can actually understand it. | Physics | explainlikeimfive | {
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"The famous line is that the laws of thermodynamics is as follows: 0th law: There is a game. 1st law: You cannot win. 2nd law: You cannot break even. 3rd law: You cannot stop playing.",
"First law: energy can't be created or destroyed. Dropping some chili doesn't destroy its potential energy, it just converts into sound, vibration and heat. Second law: most natural processes are not reversible. The chili will never recompose itself into the pot and rise back up into your hands, because the sound, vibration and heat will never turn back into potential energy. Third law: highly technical, not really that important for the layperson"
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mmduwx | Most people who die from hypothermia are found naked due to a burning sensation in the body, how does this work? | Biology | explainlikeimfive | {
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"In hypothermia, your body vasoconstricts (constriction of blood vessels) which shunts blood from the extremities to keep the warm blood to your core, where your most vital organs are. In the last stages of severe hypothermia, those mechanisms begin to fail. This causes the warm blood that was being shunted to your core to spread throughout the rest of your body, and you experience a rush of “warmth” sensation which causes you to feel hot. Thus the stripping of clothes.",
"The body rushes warm blood from deep in the body as we freeze to warm up our skin and prevent frostbite and since we have a lot of nerves in the skin we feel that warmth."
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mmeoc2 | Why are the three laws of thermodynamics not theories? Who broke them and how did they do it? | Physics | explainlikeimfive | {
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"Laws describe what does happen, theories describe how things happen. In science the meanings of those terms are different then in normal common language. A scientific theory is well supported. The theory of gravity or the theory of evolution. Both are so well supported that to deny their truth would be to show your ignorance. Laws on the other hand state the effect that will happen given a set of circumstance but doesn't say how. For instance Newton's laws of motion like \"an object at rest will stay at rest until acted upon\" that describes what will happen but not why. There are theories that describe concepts like friction or momentum.",
"Everything in science is a, part of, a theory. There is no real definition of what makes something a \"law\" but \"law\" is usually a loose descriptor given to a more simple statement or observation about the universe we believe holds true. \"Thermodynamics\" is a broad term that covers aspects of scientific observation involving heat and motion and such. In one sense it encompasses many different theories, but in another you could consider it a subset of the overarching theories of quantum mechanics. The laws, generally put are: 0. If two systems are both in thermal equilibrium with a third system, then they are in thermal equilibrium with each other. 1. Energy can be neither created nor destroyed, but can only change form. 2. The entropy of any isolated system always increases . 3. A system's entropy approaches a constant value as its temperature approaches absolute zero. Now, as far as I know, known of them have conclusively been \"broken.\""
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mmerjj | Why is there no heart cancer | Biology | explainlikeimfive | {
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"To understand why we don’t get heart cancer, we must first understand how cancer comes to be. As you may already know, our cells are constantly regenerating in order to repair the body’s damages. Each time a cell divides, it copies its DNA – and sometimes, mistakes happen. If cells accumulate enough genetic mutations (about half a dozen is enough), it may become cancerous. In other words, the body’s healing process also makes it more likely for cancer to develop. Unlike the rest of the body, the heart actually has very little cell regeneration. In fact, the amount of cell division that takes place is so low that only 50% of the cells in our hearts are ever replaced. That means that half of the heart cells we’re born with stay with us for our entire lives. Without active cell division, there is very little opportunity for replication mistakes to occur and thus, true heart cancer, originating from heart cells, is extremely rare. The cases of heart cancer you might have heard about are actually cancers of the supporting cells in the heart or cancers that have spread from other parts of the body. URL_0",
"It is possible, a malignant primary cardiac tumour can develop on the heart, it’s just rare.",
"So heart cancer is a thing. You can get a cardiac tumour. But the reason it is so rare is that the cells in the heart, termed myocytes, do not divide and regenerate at a very slow rate. Cancerous tumours grow due to uncontrolled cell division and because the myocytes don't divide, heart cancer is a very rare condition.",
"Part of cancer by definition is excessive cell division, or making new cells. Muscle cells in general, and cardiomyocytes in particular don't.. really... Do that... Whole \"cell division\" thing. They just individually get bigger as needed. Because they don't multiply under normal conditions, it makes it astronomically rare for them to become cancerous."
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mmf54n | Why did World War 1 seem to be the nastiest and most brutal war in modern history in terms of the psychological and physical effects on soldiers as opposed to more modern wars or even WW2 for that matter? | Other | explainlikeimfive | {
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"WWI was basically a tipping point in terms of technological advancement. Technology was good enough to kill people on a massive scale, but not good enough to fight a more modern war. The result is essentially a meat grinder where two sides dig a hole and shoot at each other for days on end until one of the holes is filled with dead people. Then reinforcements come in and you do it again.",
"There is a misconception about WW1 that it was all trench warfare and mud. It actually wasnt and trench warfare of that scale was rather rare and there was large variety, you could have trench lines and a few kilometers away, you would have soldiers fighting in open and rather pleasant looking fields. What made WW1 so nasty was that it was a war using old tactics with new weapons. This created a horrible meat grinder. You would have entire armies who had no doctorine to adapt to these new weapons so you could entire companies charging into machine guns because the idea of flanking or a pincher manuever wasnt perfected WW1 also saw the invention of many nasty weapons. Chemicals were used everywhere and WW1 also saw the invention of the flamethrower and the tank. This was extremely jarring to the common soldier back then who was used to horse carriges and archaic bolt action rifles. WW2 on the other hand was much more reminiscent of the wars we have today. It was a highly mechanised war where machines did the fighting. There was no time for trenches and frontlines moved rapidly not that it wasnt a horrible war in itself",
"They used chemical warfare for the first time. Plus both sides dug in and endured artillery fire sometimes for months at a time. Edit: they also shrugged off ptsd and shell shock as cowardice so no one really came out and talked about the deep fear and anxiety they had.",
"It was a time when people saw things like tanks and chemical warfare and large-scale machine gun use for the first time, combined with trench warfare in general being a large loss of life to gain not very much ground each charge. And A LOT of artillery fire that would bombard people and take (if I remember correctly) the most kills. They started using zig-zagged trenches so that when an artillery round would hit a trench, you might live since you were around a corner from your buddies Also trench life had its own problems outside of active combat with things like trench foot.",
"It was supposed to be the war to end all future wars but rather shamefully most of the worst atrocities occurred during ww1 not quite holocaust levels but still pretty bad shit happened to a lot of people back then we had never had anything to compare it to eg previous battles or wars. The biggest atrocities occur when both sides think they are the good.",
"I don't believe WWII in any way seems lesser in it's toll than WWI. It's just the toll in human lives and the profusion of stories due to the magnitude of both wars that brought home the cruelty and scope. Everyone knew someone who was lost, injured or took part. That said, if ever we have another world war the previous ones will pale in comparison. We will be lucky if any remain to discuss it. Edit; I see all the posts about new tech and chemical warfare during WWI. The truth is no recent soldier has had a easier time during a heated conflict than a soldier during an earlier time (foot soldiers at least). Methods of killing men have not gotten \"easier to take\" as time has progressed. Lower intensity battles and higher levels of domination by more technologically advanced countries has not made it any easier for the losing soldiers."
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mmfll3 | How do the deciduous trees know when autumn begins, and when it's just a cold front? | Biology | explainlikeimfive | {
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"Deciduous trees (trees that lose their leaves in winter) aren't actually responding to the cold, they're responding to changes in the quantity of daylight. These trees have chemicals inside them all the time that break down the chlorophyll in their leaves, and then break down the stems of the leaves so that the leaves fall off the tree. Light breaks these chemicals down, and the tree has to keep producing more of them. In each hemisphere of the Earth, summer is marked by a shift of the Earth's axis so that that hemisphere gets more sunlight (days are longer), and the other hemisphere gets less sunlight (days are shorter). As the amount of daylight hours decreases, the amount of these chemicals being destroyed by the light is reduced. When too much of the chemical remains in the tree, it starts to break down the leaves. EDIT: Fun fact, this is also related to why maple syrup is harvested in the winter and not the summer. Trees have vein/artery like structures called xylem and phloem that help transport different nutrients, waste, and water through the trunk (this is how nutrients get from the roots to the leaves, for example). Xylem transports mostly water. Because there isn't a lot more in the xylem other than water, the water would normally freeze in the winter, and the freezing would cause the xylem to explode as the water expands (in fact, you may hear or see this on trees in forests with cold winters, it may appear as a bulge in a tree, or the be source of a loud pop from a tree during cold winter days or nights). To help prevent this, trees pump other nutrients into their xylem during the winter - primarily sucrose, which helps to lower the freezing temperature of water, meaning it has to get colder before the water can freeze enough to destroy the xylem. That means the contents of the xylem during winter are mostly a water-sugar mixture which can be boiled down into a syrup (this can be done on more than just maples, but maples tend to put a lot of sugar in their xylem, meaning it requires less boiling to make the syrup - hence, maple syrup)."
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86
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mmfnsd | how does plastic get turned into yarn/fabric? | We’re starting to see companies taking plastic bottles etc. and turning them into clothes, backpacks, all sorts of things. How does hard plastic get turned into a soft fabric that can then make something and flexible and soft as clothing? | Chemistry | explainlikeimfive | {
"a_id": [
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"text": [
"The basic process of turning plastic into cloth is to melt the plastic or solubilize it in some type of solvent and form it into very thin threads which are then pulled together into thicker threads or yarn. These thicker threads or yarn are then woven into cloth just like your windbreaker or jeans are now. There are varying degrees of hardness in used plastic such as water bottles. Some water bottles you can easily crush with your hands while others are very strong and resistant to deformation. The hardness/softness of the plastic will translate into flexibility and brittleness once made into a thread. Certain plastics are better than others for turning into thread for garment making. Another approach would be to blend our materials into software materials to get the right properties for fabric making."
],
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9
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mmgeo9 | How does a “corporation” pay taxes? | When phrases such as “Amazon paid 0 in taxes” are said, who exactly is this referring to? Is this Jeff Bezos? | Economics | explainlikeimfive | {
"a_id": [
"gtr8ndf",
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"text": [
"Corporation taxes are paid, or not, by the company accounts department out of corporate funds. Only in small one person non-incorporated operations is it paid by an individual, and even then usually from an account in the name of the company.",
"There are rules in the tax code that let you carry losses forward or backward. Amazon lost money for years. So if you don’t earn anything, you dont pay INCOME TAX. When you do start making a profit, you can offset that profit with your past losses to reduce your tax burden. Now amazon may pay 0 INCOME TAX, they are still paying a ton in other forms of taxes. Also the shareholders of amazon are also paying taxes on their cap gains and dividends."
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mmghw4 | What happens to air when it's exhausted into outer space? | Physics | explainlikeimfive | {
"a_id": [
"gtr8yy6",
"gtrbn6j"
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"text": [
"It expands until it reaches the same pressure as its environment. Even in outer space there is some gas floating around. For all engineering (and breathing purposes) we often ignore it in calculations, but it's still there.",
"It disperses around until the pressure equalizes. That just means there’s a few molecules of oxygen, nitrogen and CO2 here and there, but at very low density, so you can average it to more or less nothing, just like the rest of vacuum."
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mmhd44 | How does a photon NOT experience time? | Photons don’t experience time, how does that work since it obviously takes time to get from Point A to Point B. | Physics | explainlikeimfive | {
"a_id": [
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"text": [
"*tl;dr: from the outside, its time slows down completely because it is going so fast. From the inside, the universe is flattened so it runs out of space as soon as it comes into existence.* Photons not experiencing time comes from Special Relativity. *Disclaimer: We are not allowed to apply Special Relativity to photons or other things travelling at light-speed. However, it applies to everything travelling slower, and we can take the limit and see what happens.* So we need to talk about time dilation and length contraction. If something is travelling at some speed relative to you its time runs slower, and its lengths get shortened in the direction of relative speed. So if a 500m long spaceship is travelling past you at 3/5ths the speed of light, its time will be running at 4/5ths the speed of yours (for every 5 ticks your clock makes, its will make 4), and it will appear to be only 400m long (so if you had two space-bouys 400m apart there would be an instant where you could see both either side of it). The 4/5ths is the reciprocal of the Lorentz factor for something travelling at 3/5ths speed of light - effectively the \"magic-squish-factor for that speed.\" That is basic SR. The maths is fairly simple; equations of straight lines. If you are really interested it can be fun to put some numbers into scenarios, draw some graphs, and see what happens. So, now we can apply this to our photon. From the outside (our perspective) the photon is travelling at the speed of light (taking account of the disclaimer above). That gives us a magic-squish-factor of 0. Applying that to the time dilation effect, for every tick of your clock, the photon's clock... doesn't tick. So nothing can happen to it. Similarly, applying the length contraction effect, it will be flattened in the direction of travel - infinitely thin. But now let's look at it from the photon's perspective (we are not allowed to do this in SR, but who cares about rules!). From the photon's perspective it is stationary and the rest of the universe is moving at light-speed towards it. So from the photon's perspective no time passes for the rest of the universe. But remember the length contraction effect! From the photon's perspective the entire universe is completely flattened (in the direction of travel). If the universe is completely flattened there is *no distance between where the photon is emitted and where it is absorbed*. The two points are in the same place. So the photon takes no time to get between them; it is immediately emitted and absorbed. It immediately runs out of universe."
],
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14
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mmhr2b | Why does coffee have to sit in a French press for like 5min to be strong enough, whereas with pour over the water is only in contact with the grounds for 10-15 seconds and produces a similar strength? | My first guess is that it has something to do with gravity pulling out the flavor as it narrows through the tunnel of Godly caffeination, my second guess is absolute fucking magic... Edit: haha ELI5 makes you pick a flair but I literally cannot think of a subject that doesn't relate to coffee so we'll go with "physics." | Physics | explainlikeimfive | {
"a_id": [
"gtri7ua"
],
"text": [
"Ahh as a physics person that loves coffee, this just makes me happy. This has less to do with physics but rather coffee preparation. If you take a look at any coffee brewing guide they will recommend that you grind coarser for french press, and finer for drip. Coffee is made when water \"washes\" off the soluble material from your coffee beans. Larger pieces of coffee (like those that you'd use for french press) have less surface area than finer ground coffee (like drip coffee). So while contact time between French Press and Drip differ vastly, the amout of soluble material that the water extracts for each method is similar due to it's grind size. Similarly, that is why you need an insanely fine grind for espresso because all the extraction happens in 30 seconds."
],
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60
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mmhtf8 | Are bugs/flys/bee, etc. territorial, as in they know of a home base? If one flys into my car and then escapes 20 miles away, are they screwed or do they continue with their bug life at that location? | Earth Science | explainlikeimfive | {
"a_id": [
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"text": [
"A fly will just keep on being a fly. A bee will immediately start flying directly home. An ant would just kinda wander around aimlessly until it died. It depends on the bug.",
"When we were packing up our house, we didn't notice something significant. Once we unpacked our washing machine, we realised that we had transported a bunch of toads halfway across the country."
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mmi223 | Why is it that when lightning strikes land a person can still get electrocuted even after being 10+ feet away from the strike zone but when electricy hits a big body of water fish don’t float up to the surface dead? | Earth Science | explainlikeimfive | {
"a_id": [
"gtrjih4"
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"text": [
"Some do, but you should never be in the position to see them. Regardless, [most of the electricity is on the surface, so any fish beneath the first foot should be fine.]( URL_0 .)"
],
"score": [
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"https://www.weather.gov/safety/lightning-fish#:~:text=So%20why%20don't%20all,the%20surface%20and%20are%20unaffected"
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mmj79g | how bug barriers (e.g. Ortho Home Defense, Raid Max Bug Barrier) kill a large variety of insects for 6+ months even afte its dry? | Biology | explainlikeimfive | {
"a_id": [
"gts67r9"
],
"text": [
"Those are best case scenario tests. Basically, the spray is applied to an area. Then they put some bugs in the area. They count how many bugs die, and how many bugs come back to the area. “Up to” is a very important part of the sentence. These products say they will prevent bugs for “up to” some amount of time. All they are is a product that kills bugs. You spray, bugs die. Most bugs found in a home are scout bugs, they find a new source a food and tell the colony where it is. If you kill the scout, it will take a long time for a new scout to come along. So, when testing, they see which bugs come to check out and area and then die, and then time how long it takes for a new scout to come along. Unless you have lots of bugs in your house, it is best to not use pesticides, and instead continue to keep the house clean of unsealed food and other food like items for bugs. For example, cardboard is a wonderful source of food for cockroaches. Then mice will eat cockroaches. If you have a really large bug problem, keep all food in a sealed container, plastic or glass. Mind you, cockroaches can find any opening and rats will eat through a lot of stuff, so it must be sealed right."
],
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12
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mmjfj1 | Why does a computer screen appear brighter when viewed from above, and darker / of a higher contrast when seen from below the face of the screen? | for instance when you tilt the laptop screen too far towards yourself or too far backwards. Also, this doesn't appear to happen with a phone | Technology | explainlikeimfive | {
"a_id": [
"gtrx7vu"
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"text": [
"The answer is, it depends on the screen. Electronic screens are complicated devices. Essentially we have many “pixels” that emit light of varying colors, but.... how do we do that? There are different ways to physically make a screen that does this, and each has different concerns. Some have small viewing angles, where each “pixel” is only directing light mostly forward. Viewing the screen from above, below, the side, ruins the brightness or color or some other aspect of the image. Other screens keep their color and brightness even when viewed nearly from 90 degrees. They would differ in price and materials. On a technical level, different display technologies can have almost nothing to do with each other. They all make a screen with pixels, but *what it’s made of* and *how it works* are different. Your phone might have an expensive screen with great viewing angle, because it’s small. But a screen like that might not work on a laptop. They could pull different amounts of power, weigh different amounts. They’re also completely unrelated to a CRT screen, which literally uses a massive electromagnet to bend a stream of electrons to only hit the parts of the screen it wants to light up."
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