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o2hgkm | Why can't you hold your breath back-to-back for the same length of time? | Let's say I hold my breath for one minute. And then I quickly expel the air and immediately take another deep breath in. Why can't I hold my breath for as long the second time around? And why can't my body simply return to breathing normally after holding my breath? Why do I have to take many quick breaths before reaching a normal breathing rhythm again? Does it have to do with my body's muscles getting fatigued? Is it somehow related to my lungs? | Biology | explainlikeimfive | {
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"You don’t just have oxygen in your lungs, you also have oxygen in your bloodstream and as the oxygen in your blood stream is depleted it takes some time for your lungs to oxygenate your blood again",
"While you're holding your breath, carbon dioxide is building up in your lungs. When you breath out, you don't completely empty your lungs, and replace 100% of their capacity with fresh air, so if order to get back to a \"normal\" carbon dioxide level, you need several \"cycles\" of fresh air through your lungs. Your body's natural reaction is to do fast shallow breaths, to cycle out that excess carbon dioxide quickly."
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o2i4xf | Why do we have powdered sugar not powdered salt? | Other | explainlikeimfive | {
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"Flour Salt, also called popcorn salt, is the powdered variant of salt crystal used by humans and looks very similar to powdered sugar when put in a bowl or on a plate. It is used for coating things in salt (such as popcorn) or when you want salt to dissolve very quickly in something and may not have time to heat it (such as with some sauces).",
"You can make powdered salt. It just isn't needed and so it isn't popularly sold. What ever your use for salt is (in cooking) powdered isn't needed."
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o2ign4 | How do chemical and electrical communications differ from one another? Specifically in regards to living organisms, i.e. humans. | It is my understanding that life forms use both chemical and electrical signals to communicate. I know chemistry is elements forming compounds through electrical bonds, and therefore electrical in a sense. But just because a copper wire has electrical bonds in its chemistry that’s not the same as when a current is sent through the wire. What I’d like to understand is how do livings organism us chemical communication and electrical communication and how are they different? In depth responses are appreciated. | Biology | explainlikeimfive | {
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"Very good question. The human body utilizes both chemical and electrical signaling extensively. One type of cell that uses both is prolific throughout your nervous system: the neuron. The neuron uses chemical signalling via neurotransmitters. These in turn affect various gates and change the amount of \"stuff\" that's let into the cell. Now what you have to understand is that current fundamentally is just a movement of charged particles. Voltage is a difference in potential, so it is in turn a difference in concentration of these charged particles. Your body is full of these, and notably Na+ (Sodium) and K+ (Potassium) are let in when a neuron is ready to send out a signal, or action potential. So, a neurotransmitter is a chemical, which opens a gate in a cell. This gate then lets in ions, which are sitting in the fluid around the cell, thus generating a current as they rush in, and changing the voltage inside the cell (the difference in charged particles from the outside to the inside). Once this voltage hits a certain amount, the neuron releases an action potential, which is essentially a rapid rise in voltage across the cell membrane as it lets in more and more ions as the sodium channels are opened up. This current is carried along the neuron's body, and propagates through its axon. Propagation essentially consists of a series of cell membranes being charged and depolarizing as the ions travel through, changing their voltage. So to summarize, at the end of the day electricity is just created by a movement of ions. In the human body, this is regulated through chemical processes. I have to leave now, so I had to hurry up this response, but I'll look to clarify it later. Feel free to ask any questions!"
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o2iwbc | How did the Incas performed blood transfusions? | Other | explainlikeimfive | {
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"very badly, probably. We don't have too much evidence for how they actually performed the transfusions, most of our evidence for the transfusions themselves is medical. Nonetheless, we can make some sort of an assumption. We know that they were capable of making rudimentary [syringes]( URL_0 ) using hollowed-out bones. So likely, they bled a donor, then injected it the good old way into the recipient. In most of Europe this type of an operation was pretty fatal before we figured out blood types, but evidence shows that most Incans had a similar blood type (O), so their success rate was much higher."
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o2j9yo | What are cookies? | I'm referring to the ones such as when you visit a website, and there is a notice that says "this site uses cookies" | Other | explainlikeimfive | {
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"When you visit a web site, the web server can ask your computer to store a short bit of text on your computer and to send it back the next time you visit. The original idea was that this: Say it's an online shopping site, it might ask your browser to store \"customer: 12842\", where that is your customer account number. The next time you come back, your web browser will tell the server \"By the way, last time you asked me to store 'customer: 12842'\" and the server will know it's you and can greet your with your name, and your half-filled shopping cart. In principle, any cookie information is only given back to the same server that put it there. Now, for the catch: Say, there is a little \"Facebook\" button at the bottom of some news web site. To display the button, your browser sends a request to the Facebook web server to ask for the image with the Facebook button and logo. In doing so, your browser tells Facebook which site it is one and also transmits any cookie that Facebook may have put on your browser previously, and these cookies may contain your Facebook account number. So, now Facebook can connect and knows that you (as identified by your Facebook account name in the cookie) are interested in the topics of this news site (as identified by the address of the web site that contained the Facebook button) and Facebook uses this to tailor advertisement for you. Facebook, of course, has buttons on many pages of many news sites from many different news publishers, so they will get a good idea what kind of news you like to read. So, the advertiser follows you around, collecting information on what sites you visit. You might not like that, and this is why the site is legally required to inform you about that."
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o2ko3b | What does 'Legitimate Interest' mean/include on cookie banners? | Is there an agreed definition of what can be considered a site's 'legitimate interest', and if yes, what is it? Or is it just the wild west, i.e. 'this is my site and I say it's in my legitimate interest to maximise my income by tracking and selling your data in exchange for my content'? | Technology | explainlikeimfive | {
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"To give an over-simplified explanation that its appropriate for this subreddit: \"Legitimate interests\" are defined as part of the GDPR (the General Data Protection Regulation that governs data privacy throughout Europe), and they are one of the reasons why a business or website might collect personal data. Sometimes \"consent\" is requested, but it can sometimes be difficult (or really annoying for everyone) to try to get consent for every single thing. So, \"legitimate interests\" are those reasons why a business might collect personal data where you might reasonably expect a business to need that information. For example, a business that sells physical goods through their online store will need your name and delivery address (and possibly phone number and email) so that they can send your purchase to you - the business might just decide to collect these details as part of their \"legitimate interests\" rather than asking for your consent to let them use these details, because what if you don't consent to providing your delivery address, or withdraw your consent to them storing your name (which legally they must for six years, as part of their accounting obligations)? Therefore, a business or website doesn't need to ask for your consent to collect personal data for these \"legitimate interests\", but they do still need to ask for your consent to use your personal data for other things such as adding your email address to a mailing list for marketing. Of course, it's a bit more complicated than that, but hopefully this will help to simplify and explain things for you.",
"It's self-defined, but obviously if someone wished to challenge such a wide interpretation of legitimate interest as you've given, they could sue the website. It would then be up to the Courts to make a final ruling.",
"Wild West, they can choose whatever definition they want - just say no to everything especially when Apple asks if an app can track you. They’ve given that option so you can protect yourself so do it Source: I’m a dev, I work with cookies Slightly off topic because this isn’t cookies specifically but… Used to work for a larger retailer and the amount of data they collected was crazy - most of it unused but “might be useful one day”. They used to have “data warehouses” (huge servers) to store it all but that became too cumbersome so they implemented “data lakes” (massive storage) instead. Essentially all that data just gets poured into a “lake” and just collected and collected. Then one day when you need to target a specific subset of people, you run a query and grab whatever data you need to push ads/products to them Now that’s just one company that only wants to sell you things… push that out to multiple governments/bad actors across the world with much bigger resources and a potentially worse intent (either now or in the future) and you can imagine the scary consequences and/or dystopian nightmare we could one day find ourselves in… Limit the amount of day you give away wherever possible. Get a VPN (recommendation: Proton) and use Duck Duck Go (browser and search), close down any old accounts you think of and no longer need etc etc etc"
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o2kwbj | how exactly speakers recreate let's say a human voice. I'm not talking about analog or digital conversion, i know a bit about those subjects. But the physical act of a speaker cone moving back and forth, perfectly recreating a human voice or any other kind of recording seems like magic to me | Physics | explainlikeimfive | {
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"To answer your question - first we need to understand what is sound. Sound is nothing but a wave (of energy) which propogates through air (and other objects but lets ignore them for a while). Something like - compressed and rarified air (along the direction of its travel). Now if you have a 'membrane' (which is nothing but the cone of the speaker) that vibrates to and fro - it can create the same compressions and rarefications in air (in front of it). So when the membrane moves ahead it compresses the air and when it moves back - it rarefies it. The movement of the membrane is determined by electrical signals (which are in turn determined by some internal logic which determines how fast / how deep the membrane needs to move for specific sounds). Again all sizes / types of membranes are not equally effective for producing all types of sound (deep or high). So you have large membranes (bass speakers) which create bass sounds (low frequency) very effectively and small membranes (tweeters) which create high frequencies better. Thats because its easier to make the small membrane vibrate at higher frequencies as compared to the larger membranes (without creating any unwanted distortions)."
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o2m7y4 | What causes morning breath? | Biology | explainlikeimfive | {
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"Plaque. Bacteria build up on your teeth. Bacteria break down the calcium in your teeth, and when bacteria fart, it smells. Some of the bacteria that thrive on your skin are responsible for BO, for example. The ones in your mouth get a nice block of a few hours to do their worst, until you wake up. You can also have tonsil stones, wee buildups of bits of food and bacteria in the folds of your tonsils. These are absolutely honking!"
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o2m83j | How can videogames render many frames of high-quality 3D graphics every second, but rendering just one image in a 3D software like Blender can take hours? | Technology | explainlikeimfive | {
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"Video games cheat, blender doesn't. As you said, video games need to render their world in just 0.03 seconds. That doesn't leave a lot of room for fancy tricks and detailed calculations. If you really stop and look at a video game world you'll quickly notice the \"high-quality\" image has a lot of things that are wrong. Video game lighting usually is super simple. Shadows tend to be wrong, not match the light sources (or just the strongest light source), or be prebaked all together for things in the environment that do not move. Textures and models that are far away are usually just crude approximations of their close-up versions. Reflections typically are crude or missing entirely. Everything not physically on screen is not rendered. Cloth, grass, hair, and everything that has many very detailed things in groups will often move as uniform clumps instead of bothering to render each hair with accurate physics, and so on and so forth. Blender will usually follow whatever setting it is set to, but by default it will try to make whatever it is rendering as accurate and realistic as possible. Every ray of every light source is mapped and ray-traced, every texture is taken in to account, every shadow is factored in from every light source, reflections actually work correctly for reflected surfaces, everything that exists in the scene is rendered because it may affect the things on screen as well as off. Blender has the time to do rendering properly, whereas video games do not, and thus cut every corner they can think of.",
"Video games use a bunch of tricks to speed things up. For instance, not all shadows are dynamic. Many are \"baked\" into the texture they're falling onto beforehand and that process takes hours during development. But when you see it it just loads said shadow as an image texture and doesn't have to do a bunch of dynamic calculations. I don't know the full answer here, I'm sure there's more, but part of it is that it does actually take hours for some things, they just make sure those hours are spent behind the scenes lol."
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o2m8op | | Why do some words roll off the tongue, whereas others cause breaks in speech? | For example: Break: ABCDEFGHIJK Roll-Off: LMNOP You can say "LMNOP" much faster, because it "rolls off the tongue". This is the first example I could think of. Why does this happen? | Other | explainlikeimfive | {
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"Some letters are more complicated to say. For example, the vowel sound for A. It's not just a single sound. If you focus on what you're doing, you'll realise your tongue starts low and towards the back of your mouth, but it ends forward and higher. It starts sounding like the vowel in \"bass\" and ends like the the vowel in \"key,\" for example. This takes time. Others, like H, require a break before you start them. H is called the aspirant, because it starts by just breathing out. F also needs a bit of a break after the E. B, C, and D make your bottom lip do a bit of gymnastics. B and D start with your lip in one spot, but C starts with is further forward. So it kinda has to jump back and forth. Meanwhile, LMN has a sort of constant vowel sound, and just uses a flick of the tongue or a quick pinch of the lips to break it up."
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o2md79 | Why does rabies make people hydrophobic? | Biology | explainlikeimfive | {
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"*Why* is because it makes your saliva thicker and stickier. That's what causes the foaming of the mouth associated with rabies. The thicker saliva holds more virus, so it spreads better. *How* partially involves just eating holes in your brain that make you irrational and dislike water. It also causes loss of control over your muscles and often painful muscle spasms. This very much includes muscles in your throat. It begins with difficulty swallowing, so you kind of feel like you're choking when you try to drink water. As it progresses, the spasms make it impossible to swallow. It's also very painful. So trying to drink water makes you feel like you're choking and drowning, while you're also becoming more paranoid, delusional, and irrational. Eventually, just *looking* at water causes your throat to spasm in anticipation of drinking - by this point you're horribly thirsty, your body demanding that you drink the water in front of you, but your rotten brain is panicking at the choking and painful spasms in your throat.",
"When you drink water there are many muscles working together to get the water down to your stomach. In encephalitic rabies you begin to have spasms (severe, involuntary contractions) of your muscles and the spasms can be triggered when you try to use the muscle. In rabies, when you try to drink water the muscles in your throat begin to spasm as they try to move the water down to your stomach and the water won't go down. Your wind pipe (trachea) and esophagus initially share the same tube, the pharynx, so you also can't get air into your wind pipe to breathe until the spasms stop. To make it worse, the spasms don't just stop the second you stop trying to swallow, so it can be minutes before you can breathe again. This creates an intense fear of swallowing. Eventually, just the thought of swallowing can cause the spasms to happen. Though rarer, you can also get the same thing when you try to breathe. The muscles in the pharynx can spasm when air his them so air can't get into the lungs. The diaphragm can also spasm. Your lungs at baseline want to be small with no air in them but the diaphragm, a muscle at the bottom of the lungs, helps to keep your lungs from collapsing and having no air. Breathing in, inhalation, occurs because your diaphragm contacts and pulls the lungs open. This creates a vacuum in the lungs and air rushes into the lungs to fill the vacuum.When the diaphragm relaxes, the lungs can go back to their preferred form, empty, and the air is pushed up into the pharynx then out your nose or mouth. The entire goal of breathing is to get oxygen in the body and carbon dioxide out of the body. Spasms of the diaphragm keep you from doing either of these and you begin to suffocate. People have died from the spasms of the diaphragm. Hope that is clear.",
"I always think of [THIS STORY]( URL_0 ) when someone mentions rabies. Holy lord fuck that's fucked up.",
"Not an answer to your question, but FYI: if you suspect having been bit by a rabies infested animal, wash the wound with preferably green soap and water (if not possible any other soap/detergent available) for like 15 minutes and contact the nearest hospital/doctor to get vaccinated!! Even when you're already vaccinated you still need 1 or 2 vaccins after being bit!! Source: a tropical diseases specialist doctor who vaccinated me when i went to Indonesia for 6 months to work with wildlife and dogs."
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o2mdny | when a video you're streaming is buffering, why does it load faster when you rewind a little as opposed to just letting it buffer on its own? | Technology | explainlikeimfive | {
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"Id imagine 1 of 2 things is happening. 1. Your restarting the buffer/download and it could be getting a better connection the second time. 2. Its an illusion and its not faster you’ve just wasted enough time rewinding/waiting for it to buffer that when you watch the thing the content is now loaded far enough that watching the movie won’t catch up.",
"Sometimes, computers get stuck. Things can glitch, and maybe it gets caught in a loop that it's never going to exit. The rewind forces it to try again, and hopefully it'll do the right thing. Humans do this too. Ever tried to tell someone something, realising your just spouting nonsense, and then you pause and start again? Same idea."
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o2n6cl | Why do we have to brew tea or others herbs instead of eating them raw? Why (probably) can't we get the same health benefits from dry herbs? | Biology | explainlikeimfive | {
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"You can (and many people do) chew fresh herbs, either for their taste or their perceived health benefit. But fresh herbs only stay fresh for a very short time after being picked. Within a couple of days they're usually starting to go limp, to lose some of their flavour, and generally to be less desirable. So the answer to that is to dry the herbs and distribute them in their dried form. But then they're quite unpalatable: putting a handful of dried herbs into your mouth is not far different from shoving in a handful of sawdust! However if you steep the dried herbs in hot water for a few minutes, you get a reasonable compromise: a product that can be easily distributed and stored for months, along with an experience for the consumer of something that tastes good and isn't unpleasant.",
"Just adding a note about cannabis. THCA isn’t psychoactive, but once it’s heated (the technical term is decarboxylation), it becomes THC which is psychoactive. That’s to say, the chemistry of plants changes when you add heat. Edited to add: that’s why you can eat a bud of cannabis without any harm or true high, because there are only trace amounts of activated THC in the flower.",
"Tea can actually be eatten freshly picked or arranged in different recipes, though it becomes less delicious the further from first flush it it.",
"What health benefits from what herbs are you refering to ?",
"Some herbs require heat to be activated. Some herbs have their benefits hidden deep within them, like bone marrow, and you have to boil to get them out. Sometimes, it''s purely because those herbs have been dried and your body can't digest those vitamins/minerals etc when the source is so dry that you might as well be eating paper."
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o2phhp | what the United Nation supposed to do? | Other | explainlikeimfive | {
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"It’s to protect world peace and address the concerns of all the different governments, the idea behind it is if you don’t let quarrels grow there won’t be war. They also condemn and place sanctions on countries who are violating things like the human rights agreement This is in theory, in practice they fucking ignore genocides and have no real power",
"They are pretty explicit about that in their Charter: > The Purposes of the United Nations are: > To maintain international peace and security, to take effective collective measures for the prevention and removal of threats to the peace, and for the suppression of acts of aggression or other breaches of the peace, and to bring about by peaceful means, and in conformity with the principles of justice and international law, adjustment or settlement of international disputes or situations which might lead to a breach of the peace; > To develop friendly relations among nations based on respect for the principle of equal rights and self-determination of peoples, and to take other appropriate measures to strengthen universal peace; > To achieve international co-operation in solving international problems of an economic, social, cultural, or humanitarian character, and in promoting and encouraging respect for human rights and for fundamental freedoms for all without distinction as to race, sex, language, or religion; and > To be a centre for harmonizing the actions of nations in the attainment of these common ends.",
"The UN is a forum for nations to get together and discuss their grievances and issues, and in theory pool resources and efforts to deal with issues that impact everyone. It has done some of that, but also sometimes devolves into grandstanding and bickering. It’s not meant to be a world government or have any true enforcement authority, the more powerful member nations would never agree to that."
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o2qpp1 | Waves come in at New York, and waves come in at Europe. What happens in the middle? | Earth Science | explainlikeimfive | {
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"Waves are not current. Waves are really just pulses of energy and can pass through each other. They are mostly generated by wind. They can reflect and refract like light. In the middle of the ocean, most of the waves travel in the direction of the wind. When the wind changes direction, the already generated waves will keep traveling in the same direction (and will eventually dissipate) and it will start generating waves in a different direction. As a result, the open ocean has sets of waves traveling in several directions. Form the perspective of a small boat, there will be a main swell and then \"under\" it, you can usually notice secondary swells traveling in different directions. Waves go slower in shallower water. Like light entering a lens, this causes the waves to turn towards shore. As a result, any waves traveling at an angle towards the beach will get steered straight towards it.",
"Giant waves in between. They are harder to notice because the whole ocean is moving/they are more underwater. Imagine the earth is a cup of water, and if you move it around, the water goes from one side to the other, you don't really notice the peak of the water moving in the middle but you do when it hits the sides. Now imagine the cup is a ball (Earth) instead and gravity is holding the water in at all angles, give it a spin and that's what we got.",
"There are waves in the middle. Waves \"come in\" because the water is getting shallower as you get close to the beach/coast. In the middle, they just go up and down.",
"Most of all the waves are cause by wind. The friction between the wind and the water causes waves to form. You can verify this by blowing over a pan of water. Especcially in open water, waves can build up energy, becoming very long in wavelength and high in amplitude. Near shores it gets less deep, this forces the waves to become of shorter wavelength and slower. Because of this, the waves always turn towards the shores, and not in the original wind direction. Also, I am surprised by the amount of bad answers i read in this thread. Many people apparently overestimate their knowledge on this.",
"The waves pass through each other in the middle. When the waves hit a shoreline some of that energy gets reflected and begins moving in the opposite direction, back towards the other shoreline on the opposite continent. Most waves aren’t perfectly reflected though so they end up moving at angles to each other which allows them to move past one another without too much energy loss. And some waves moving towards the same shoreline will meet up and add together. The moon also adds energy by constantly pulling on the water as it gets closer and farther over the night cycle. You can try the experiment yourself in the bathtub, stay as still as you can and wait for the bathwater to calm to a still state, then just push your hand through the water towards the back of the bathtub and watch the wave bounce off the back. It will then travel towards the front and then bounce towards the back again. Here your hand is adding energy like the moon and you can start to get predictable tides if you add waves at a constant rate.",
"More waves. Wind blows the water to create most surface level waves. This happens in deep water as well.",
"Waves tend to go in the direction of the prevailing wind. The waves don't actually move, the energy spins in a circular motion. The energy goes down in front of the wave and up in the tail of the wave. The the faster the wind blows over the fetch ( distance and duration the wind blowing the same direction), the more energy builds up. The amplitude of the waves increase as the depth of the water decrease because the circling energy starts pushing against the bottom. When the depth of the water reaches 1.4x the height of the swell, the waves breaks. Swells are measure by period in seconds and amplitude ( ft in USA ). The the larger the period the period the faster the wave energy moves, resulting in a bigger breaking wave. The more quickly the depth of the water changes the more powerful the wave break. Look up the heavy deep water Reef breaks ( Jaws or Pipeline ) vs mushy beach break in the Gulf of Mexico. A seismic wave (tsunami ) is very low amplitude but travels almost 2x as fast as a regular wave.",
"A good way to think about it is if a tsunami was approaching. The tsunami is barely noticeable out in open water below you, but closer to shore you get, depth is lower so the only place the wave has to go is UP.",
"I dunno, I find all these explanations quite weird for a 5 year old. The water is moving the same anywhere, put a wall /coast anywhere in the ocean and you'll get the same thing. Imagine a pool, water \"waves\" up on the sides, but it also waves up against you, just because you're in the way"
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o2rczr | Why do some of the grains(chikpeas etc) stay hard/raw after soaking in water and others get sprouted? | Other | explainlikeimfive | {
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"Some grains/legumes just take longer to hydrate and sprout. It will still happen, that's how we are able to grow more chickpeas!"
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o2s5aq | Why does our skin "peel" after a sunburn? | Hi! Summer is coming and like many people I underestimated the sun which gladly gave me sunburns around my neck. Since a few days it started peeling and I was wondering why? And why is the skin under it so sensitive? Thanks and happy Friday! | Biology | explainlikeimfive | {
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"Well you've burned the skin, that's a trauma as far as your body is concerned. It tries to get rid of the damage and regrow underneath. The fresh new skin is not as hardened and nerve endings are less protected.",
"The skin peels because its dead and that's what happens to dead skin: it peels away and falls off. This is a process that happens normally all the time but with a sunburn you have a large, contiguous patch that has been killed all at once. The skin under is sensitive because it is thinner. You literally have less skin, and therefore less protection, at that location so the nerves are more exposed."
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o2u8pe | What do singers mean when they say they "sing from their gut" and "not their throat"? | Edit: Thank you for all your great answers! | Biology | explainlikeimfive | {
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"I'm not an expert on singing technically, however I do know the difference between the two. They say 'sing from the gut' meaning to use the diaphragm. Which is a muscle that holds up your lungs. When you use those muscles, you can get more than from using the throat as it sounds fuller and you can get more air out to sound better. Using the throat strains your vocal cords and can cause soreness and raspiness. To sum it up, the diaphragm feels more natural, and doesn't hurt, the throat does. I hope this clears it up.",
"Opera singer here — if I want to make a LOT of sound, I need the effort to come from the larger muscles of my body and not the fragile folds of tissue (or, more usually, a bunch of other muscles surrounding those folds of tissue that like to jump in and “help”.... but that’s not helping). I use my pelvic floor, my back, my belly, my ribs, a feeling of rooting my feet into the floor, to cue a more integrated and efficient movement that will allow for correct resonance. It feels a bit like I’m a giant pufferfish trying to maintain that expansion against the exhale, but all in a way that feels really good, makes a LOT of sound, and doesn’t damage my voice over time. Singing is simple but it’s not easy.",
"theres the head voice also that is like the throat voice but wont cause the same raspiness over time for higher pitched singing and the chest voice is what you use when you shout or project your voice alot, a way to get into it is to do a scale, and pay attention to the muscles in your stomach it helps to pull in your belly button and focus on your posture. i learned how to use chest voice by doing scales with my hand first of my head then my throat then my chest, it helps to be able to feel the vibration with your hand",
"I had a voice teacher that always stressed this, and it very literally just looks like using your belly a LOT for breath - as in you literally see your belly expanding when you inhale, and \"deflating\" as you exhale, because you're using the muscles in your abdomen to push the air out. The example he always gave me was toddlers/babies - they can scream all day long without ever going hoarse, ever wonder why? Watch their belly when they're breathing heavily; they support their breath with their gut, but at some point as we grow up we start to use our chest instead.",
"Melissa cross taught me the answer to this. Take your hands and place one on the middle of your chest, and wrap the other one under your breast/pec. Imagine you have a band wrapped around the area of that second hand and you want to break that band using just that bottom part of your chest. You do NOT want that top hand moving with your breath. It feels like you’re breathing with just the bottom of your lungs and is WEIRD the first time you do it. THAT is “gut”/diaphragm. Singing from your “throat” is that “untrained” way of singing. It’s like when you go “lalala not listening, lalala”. That very casual voice is your throat voice. It’ll get the job done but it don’t be very powerful and can’t be done long term as it’ll damage your vocal chords. Head voice is what you use when you’re making fun of someone and go “nya nya nya! I’m a stupid face and this is what my voice sounds like.” It’s all basically where you’re pushing air from, where the power behind the voice is coming from. I can’t sing for shit, but I least I know where to breath in order for my lacking talent to be heard lol! 😄😆😩😭",
"When we speak we pretty much just use air like when we breathe. When we exhale, a lot of air comes out at first and then it diminishes until we inhale. If you do that when singing, the last bit of a note will be quieter and lower pitched than the beginning. If you consciously expel air at a chosen rate by contracting your diaphragm, you have complete control of the sound's loudness. Keeping your throat muscles relaxed gives your vocal cords complete control of the pitch. And then your mouth shapes the sound.",
"Crikey. The answers here remind me of the blind men and the elephant story. They're getting part of the situation correct but they're not getting the whole story. \"Sing from the diaphragm/gut and not from the throat\" is a piece of folk advice. Like all pieces of folk advice, there is a kernel of truth and usefulness to it but it can also be inaccurate and misleading. If you literally did not sing from the throat, you would not make any sounds that would sound like normal singing because you need the larynx and vocal folds to create sounds for speech and singing and the larynx is located in the throat. And you can't sing from the diaphragm/gut because there is nothing down there that creates the sound. The advice is anatomically inaccurate but as I wrote, it doesn't mean it's not useful. The problem is is that it is quite vague advice, and different people will coordinate their bodies in different ways according to what they think the advice means. Hence the need for singing teachers and practice to recalibrate and readjust and reword so that the advice is useful to that particular singer with their particular body. Getting better at singing involves getting better at the breathing part of singing. There is this thing called \"subglottal pressure\" which basically means the air pressure below the vocal cords. There are a few different ways to control and coordinate and manage this pressure and one category of these ways is using the various muscles and structures of the torso. Higher pressure is required for louder notes and higher notes and vice versa. If the coordination for a particular note or phrase is inadequate in the torso, then something else will need to compensate in order to create the particular sound the singer is after. What that compensation is depends on the phrase and the singer. If we go back to the \"sing from the diaphragm\" advice, it encourages more torso activation to hopefully remove or reduce the compensations that existed before. But like I wrote, the advice is vague and so the coordination in response to that advice is unlikely to be the best option.",
"it means (metaphorically) sing with your nut sack! But literally from your gut not your throat because its comes out stronger, more confident, with more nuts! sacks.",
"It’s just what muscles you’re using. If you sing with your gut you’re using the muscles below the lungs which allows you get more air in and consequently much more air to play with when you’re singing. My first singing teacher had us hold one hand just over the belly button and the other on our chest. She’d then challenge us to sing without the chest hand moving, so we could get better control of our diaphragm (belly muscles).",
"Here's where 99% of new singers go wrong... They hear the phrase \"sing from your diaphragm\" and \"your belly will extend\" and then they do this... They force their belly out without actually taking in air and then let it all go once they start singing because you can't support a breath that isn't there. Essentially seeing the extended belly as proof of correct breathing when in reality nothing as happened. This actually makes singing harder. The stomach will extend out as a result of the diaphragm dropping and pushing the organs out of its way. To do this properly, your inhale should first be felt in the lower back and as an expansion of the rib cage. Once that expansion happens the belly will start to extend AUTOMATICALLY since there is now no rib cage weight on the lungs and they can fill completely up from the negative pressure created by the dropping of the diaphragm. Once they are full and the diaphragm is down it then becomes possible to hold that feeling since there is now something to hold. The support aspect will be natural, and will feel like a suspension of air, nothing going out and nothing going in. From there you can keep that feeling and start producing tone while maintaining that down and outward feeling. So if you've tried breathing from the diaphragm but didn't notice a difference in the voice, you're doing the first one. Breathe deep into the back and allow the ribs to expand, the belly will follow suit. This will make a difference in tone, so much so that you'll surprise yourself."
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o2ubfg | When testing electrical parts (inductors/capacitors) what makes some test parts to get “hot” and other cause “shock”? | When testing electrical parts (inductors/capacitors) what makes some tests get “hot” and other cause “shock”? | Physics | explainlikeimfive | {
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"Capacitors resist changes in voltage. They charge up like a low capacity battery and then store voltage. Touching them can cause them to discharge and shock you even after input power is removed. Other parts get hot because current flow produces heat. When testing insulation values on wires with an insulation tester, the wire can act like a capacitor and you need to touch the conductors in the cable together with a screwdriver or the next person who handles the cable can hurt themselves."
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o2us80 | What is a travel router and how does it work? | I hear about people using travel routers to connect devices to hotel wifi or in dorm rooms. What is a travel router and what does it do differently than just connecting to the provided wifi? TIA! | Technology | explainlikeimfive | {
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"As someone that has used these here are the scenarios for where I bring my own router and its configuration: Configuration: * The Router can connect to an available WiFi network or connect to a wired network. * It then makes a VPN connection back to my office * It then provides its own private \"to me\" wifi network and/or wired network where the network is secured through the VPN. & #x200B; The use cases: * Restrictive network access in the hotel. This is worst in Vegas, probably bad in San Francisco/New York/Seattle Particularly during conferences, hotels will have \"Free wifi\". that \"Free\" is with the compulsory \"amenity charge\" that grants you access to a fitness facility, business office, and room wifi. However, it is very often limited to 2 devices/room. If you are going to Vegas to gamble, well, fine, that probably works. But going to a technology conference? We will have 3 people in the room, each will have a minimum of 3 devices (phone, computer, tablets, whatever we are evaluating from the show, or working on for our demonstrations, or maybe some analytics devices for determining show success, etc.) Anyhow, we can expect to need 12 devices/room to be operating. At $15/day/device for a typical \"amenity\" change, that's a lot of cell phones going to the gym that can be avoided by using a single \"travel router\" connection, now our room can tunnel all that data securely out. & #x200B; * Travel to locations where your data can be expected to be scraped, spied upon, or filtered/censored From the above, this should be obvious. But maybe you aren't thinking about it when you go into that meeting room in a customer or supplier's building. They have the whiteboard setup, or the first slide of the powerpoint is the WiFi network access information. You have been traveling for 20 hours and want to get a quick message back to the kids so you connect and do that facetime meeting or whatevs. Then halfway through the meeting, you check your email… If instead you just connect your travel router to this network you can be sure your communications are a bit more secured.",
"I have one that I flashed DD-WRT on that runs a constant VPN so all my devices run through that. Hotel WiFi’s are notoriously unsafe."
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o2w7kf | Why are desalination plants so energy intensive or nonviable on a large scale? | With global warming changing weather patterns and fear of water shortages in the near future, why haven't desalination plants been a serious solution? Especially in coastal, drought prone areas such as California, Africa and Australia? | Earth Science | explainlikeimfive | {
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"This is only an amateur answer but desalination requires reverse osmosis which pumps water at very high pressure through membranes. This takes a lot of energy and is very slow. There is also distillation which is boiling water then collecting the vapor. Same two problems, slow and energy intensive. Both of these are done a lot on small scales. But to do it on the scale that farming and residences use water would require a ton of infrastructure and energy.",
"San Diego spent a billion dollars to build a desalination plant. A BILLION. It can only provide about 7% of the water needs that San Diego as a city requires. Desalination is a simple process. Boil the water. It's just that the sheer amount of energy needed to boil enough water to make a difference is huge, and we don't have the technology to produce more energy or have more efficient ways of boiling mass amounts of water.",
"Just like there is a certain amount of energy needed to heat water 30-100 degrees to boil, there is a certain amount of energy needed to desalinate water. It can be viable if there's cheap energy available. Nuclear power is the real answer. After a plant is built, it is cheap energy that is green and constant. Other renewable energy sources fluctuate based on wind, sunshine, and water flows. Unfortunately, people are afraid of nuclear power and so there are many regulations in building these plants. That makes them very expensive. There are also fears of governments enriching the nuclear fuel to make bombs. They are also safe. In Japan, there was a 9.0 earthquake, the *fourth largest in the world* since people started keeping track. This caused a tsunami that was taller than 3 houses. This was the absolute worse case scenario. Nobody died\\* & #x200B; ^(\\*Officially, one employee of the plant died of cancer 7 years later, but it's questionable if the disaster actually caused it.)"
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o2wngy | What do people mean when they say you don't actually own the games you buy digitally? | I guess this comes under both technology and economics. But yeah I don't get it. You pay money for a game, you now own that game. That's how a transaction works. If I don't own it what on earth did I pay all that money for? How can companies get away with this? | Technology | explainlikeimfive | {
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"You own a license to play said game. You don’t own a copy of the game to do what you like with it.",
"Imagine you wake up tomorrow and Steam says, “we made enough money, we quit, Steam has been permanently disabled.” (Obviously it wouldn’t happen quite like that, but still.) You don’t have a way to play the games you paid for. You don’t have a physical copy of it that you can just play without support from an outside source. You are relying on the service to continue existing. If you buy a paper book, you own it. Nobody can stop you from using it. But if Amazon wanted to, they could brick your kindle remotely and hold your books hostage for more money or a subscription service or something else. That’s really what people mean when they say you don’t own digital media; you’re paying for access to it and must use it within the framework of the digital supplier.",
"No, that's not how transactions work. For example, you pay to see a movie, you don't own that movie. You've paid for the right to see it once. You walk into an apartment and pay the landlord for an apartment, you don't own the apartment, you're renting it. It used to be you could go to the game store, buy the game and it was yours. Now (and especially with streaming and digital games such as you get with Steam) there are a whole hosts of terms and conditions you are agreeing to when you download the game. For a non-game example, I used to have a copy of a drafting software. I could load it up and use it whenever I wanted. It was, for all intents and purposes, mine. Well, it soon became out of date so I looked into purchasing a new version. Except the company that made it wasn't selling a new version, they were selling a license to use the new version for a monthly cost. And they get away with it because that's how things work. It's their software and they can sell, rent, and distribute it however they want. You aren't entitled to be sold something if they don't want to sell it to you. And when you see that big block of text and click \"I agree\" you are, in fact, agreeing to the terms and conditions under which you are accepting the software, which may include the fact that they are only giving you permission to use or play it, not that you outright own it.",
"I would also add that you don’t “own” something you buy on physical media either. You own the disc, box and manual but don’t own the contents of the disc. Digital licensing is basically the same thing other than the absence of the physical items.",
"You have a license to play the game, you don't own a copy of said game. This is how almost any software is distributed these days. Ita buried in the terms of service for the game and digital store front you use. You are allowed to play the game, but not duplicate, alter or otherwise do anything other than what the developers allow. If you owned the game, you are free to do whatever the hell you want with your own copy.",
"It's similar to a permanent rent than ownership. Imagine that you rent a home but only pay for it once, no monthly fee. You sign the usual contract and you can move right in. Most of the time it feels like it's your own home. You live there, you have your own keys, you can lock it, you can buy new furniture etc. But you're not allowed to resell it, remodel it, change the locks without notifying your landlord or rent it out yourself. You also don't own anything that was already in the home when you moved in, and you have to preserve them in good condition. The landlord can also evict you at any time, but it happens very rarely. If you break the rules you've broken the contract and the landlord can evict and sue you. Similarly, when you buy the game, digitally or physically, you don't really own it. You can't resell it, you can't dissect it and use assets from it for your own projects, or make derivative works. (Sometimes you can get away with it but officially most of these are not allowed) You can, however, play it as the developers or publishers intended. The only difference between digital games and physical disks is that they can't take your disk away."
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o2wnt5 | why isn't there a sharpest blade that can cut through stone like its butter by applying same force ? On the other hand diamond can cut diamond. What is the structural difference? | Chemistry | explainlikeimfive | {
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"Stone is hard, which means that, at the molecular level, the inter-molecular bonds are really strong and they don't stretch easily. This means it will always take more energy (more force per distance) to cut stone than butter...you have to break stronger bonds. In order to cut the stone and not the blade, the bonds in your blade material have to be stronger than the thing you're cutting. That's difficult to do with stone. Diamond has \\*extremely\\* strong intra-molecular bonds. That's why it's so hard. It's the hardest of (natural) stones. But it's not harder enough to allow you to build the kind of edge you'd need to cut stone with hand pressure.",
"Diamond can’t cut diamond. It can cleave/saw/erode it, but you’ll never get a diamond blade to carve another diamond as smoothly as a metal blade does butter because the bonds between constituent elements (atoms/molecules resp) are much stronger in diamond compared to anything else than butter compared to a knife."
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o2x11j | How is it that we can feel people staring at us? Or is it an illusion of the mind? | Other | explainlikeimfive | {
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"It's an illusion. It's been [studied]( URL_0 ), and there's no evidence that people can tell without looking. Part of it is we've evolved to observe people's eyes, so it's easier for us to notice when those eyes are directed at us. Also, turning to look at someone often makes them look at you.",
"I suspect that our awareness that someone is staring comes from sound. When you are aware of other people in your space, you expect them to be making certain sounds, when you hear nothing, it is usually because they have stilled, which would trigger your lizard brain for danger (hunting behavior, child at-risk, etc.)"
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o2xpe5 | Why do birds fly around so much? Where do they have to go each day? | I’m not talking about migratory birds, just your average bird that flies around all day making noise. | Biology | explainlikeimfive | {
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"Well they gotta eat and not get eaten and look for mates sometimes and get stuff to build nests and build them and feed babies sometimes.",
"Because they have to eat and drink while avoiding becoming someone else's dinner. Different birds have different diets, but all have a fairly high need for calories because flight is very energy consuming. Add to that the need, for several weeks, to feed hatchlings, and the demand for calories is intense. Even in a good territory, one with lots of the right kind of food for the species in question, they are not going to find all those calories in one place: they have to search them out. Water is the same: no birds' nest comes with municipal water supplied, so they have to find the puddles, streams, bird baths, whatever they can access to remain hydrated, and these won't all be in the same place day after day. Further, the time spend on the ground, or close to it, actually eating and drinking, is fraught with danger from predators seeking *their* meals, whether other birds, cats, snakes, you name it. Being able to fly when the predator cannot is pretty handy, and the smart bird will not stay on the ground where s/he is vulnerable for too long.",
"Why do you leave the house? To be social, to get food, to gather resources (money for humans)"
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o2xqg5 | why anesthesia for surgery doesn’t give us the “well rested” feeling we get from good sleep | Biology | explainlikeimfive | {
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"Sleep during surgery isn’t restful. A surgical operation is stressful for your body whether or not you are conscious. If you slept through a marathon run (or even a brisk hike) I promise it would also not be restful.",
"Sleep is far more than just shutting your brain off for a few hours. The brain remains active during sleep; its focus switches from external activities to internal housekeeping. The purpose(s) of sleep are still not well understood, but we know that sleep contributes to the upkeep of chemical balance and to the formation & curation of long-term memory.",
"Because you don’t go through normal sleeping phases like REM. You just get knocked out, I think you don’t even dream during surgery.",
"Sleep in some respects is the complete opposite from anaesthesia. In some stages of sleep your brain is more active than when you are awake. Anaesthesia generally works as a depressant which reduces activity."
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o2yijt | why do some alcoholics have a huge belly and some remain thin? | I sort of understand visceral fat, but I know people who drink a bottle of hard liquor a day with no belly, yet some remain skinny with a similar amount. | Other | explainlikeimfive | {
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"The typical beer gut is present for hard beer drinkers (typically) - beer is super high in calories - average beer is about 100-150 calories. Drink a six pack and that's the same as a Big Mac, and a six pack is pretty tame for heavy drinkers. Wine is also high in sugars, while liquor is usually around 80 calories per oz. So a whole bottle of juice and jive would be 2000 calories just about an average adult's body weight maintenance intake, mebbe a bit more. A good night for a heavy beer drinker would be a whole case of 24, so 3600 calories easy. The difference comes down to whether they're ALSO eating. The beer gut alcoholic is probably also eating unhealthily. Your hardcore 26 oz bottle of whiskey/day alcoholic probably isn't interested in eating too much (or doing some would cause them to vomit under most circumstances), the majority of their caloric intake is ONLY from the booze.",
"Some alcoholics with bellies *aren’t* fat. They have cirrhosis of the liver, which can cause the liver to physically become enlarged. This pushes the other organs (like the stomach) further out. Additionally, cirrhosis slows the flow of blood through the livers. That backup of blood causes increased pressure in the vein that brings the blood to the liver (the portal vein), which results in the accumulation of fluids in the abdomen. Aside from liver problems, alcohol contains many calories. Some alcoholics burn off fewer calories, thus leading to weight gain. Depending on genetics, this fat might be distributed evenly over the body, or may accumulate in certain areas (the abdomen being one of the most common).",
"Alcohol will be metabolized and used as calories. This is in addition to the other calories you often find in alcoholic beverages such as beer, cider and wine. On the other hand spending all your money on alcohol and drink it instead of eating food when hungry, actually preferring to go hungry to get drunk faster, is a way to lose weight because you eat less. And there are lots of other factors which play a big role in weight management, both related to the alcoholism and unrelated things."
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o2yk5o | Do people during heart transplant die and get back to life later? | Biology | explainlikeimfive | {
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"No. But that depends on how you define \"death\". When people say \"he was death for 2 minutes and then the doctors brough him back\", that person was never truly dead, it's just that his heart stopped. If you define death as whenever your heart stops, then yes. But that's not how death is usually defined nowadays. A person is considered dead when they have brain death, that is, when the major processes that keep the cognitive part of the brain alive, stop working and it's irreversible.",
"No. Before their heart is disconnected, they are connected to an ECMO machine. This machine works like their heart and lungs, keeping them alive."
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o2z47l | Why does the wind feel colder when you're wet? | For example, It could be a 100° with a breeze. If you get in a pool, and then get out, the breeze makes It feel much cooler than 100°. Before getting in the pool, the breeze did nothing. Thanks for any replies. | Physics | explainlikeimfive | {
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"Feeling cool or cold is the result of having heat _removed_ from you. When a breeze flows over your skin, there is a very small amount of heat transfer from your skin to the air molecules. A little, its not very efficient heat transfer. Same reason why you can stick your hand in a hot oven for quite a while before it feels uncomfortable - poor heat transfer. When air flows over water, the water molecules near the surface that temporarily absorb more thermal energy are more excited, so they \"escape\" (evaporate) from the surface of the liquid, taking their thermal energy with it. The transfer of heat from your body to the water on your skin is much more efficient. When that water evaporates into the airflow, it takes that heat away, leaving the water - and your skin - that is left much cooler. So if you're hot and want to cool off, go soak your shirt in the pool and put it back on sopping wet.",
"It’s called evaporative cooling. When vaporization of a fluid takes places, the droplets that are left, on your skin, are in a state of lower kinetic energy and that equates to a relative cooling sensation. Next time try misting water on your face when you’re super hot, fan yourself and feel the awesomeness. Don’t forget to use sunscreen.",
"Water needs energy to go from being a liquid (on your skin) to being a gas (in the air). When the wind blows, the water takes energy from the wind and energy in the form of heat from your skin and evaporates, making you feel colder because you're losing heat."
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o2zrev | How do prosthetics work? | Biology | explainlikeimfive | {
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"Most prosthetics don't have any kind of connection to the nervous system. Assuming you're talking about the robotic ones, they connect the nerves that used to go to muscles in the limb up to a muscle where the prosthetic attaches, then measure contractions in that muscle to figure out how you want the limb to move."
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o30re7 | Why do we cringe when we hear certain sounds | My question is about why the human body feels "scratchy" for lack of a better word whenever we hear certain sounds like when someone scratches a blackboard with a fork and also why the exact sound varies among different people. | Biology | explainlikeimfive | {
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"YES. And for me - voices especially! Like last night, was watching a show and the girl’s voice was so gravelly and sounded like she needed to clear her throat... lol I literally had to turn off the show even tho it was good because it made me feel gross, irritated, scratchy inside like you said."
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o30yaz | What is the probability that my next toss is heads, if my first two tosses were heads? Why? | Mathematics | explainlikeimfive | {
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"50% (if you don't count the rare case of falling on the edge and staying that way). The universe gives no damns about your previous throws, only the present matters and that present is you holding a coin with two sides.",
"50/50. The results of the previous tosses have no impact on the probability of the current toss.",
"It’s 50% for any coin toss- the result of one coin toss does not influence the next. But, the probability that starting from no coin tosses you end up with three heads is 0.5^3 = 12.5%"
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o311l9 | when we take anti-inflammatories, how does the medication know what swelling to target? Or would it just decrease any swelling anywhere? | Biology | explainlikeimfive | {
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"Swelling is the result of an immune response from the body. It's a natural defense mechanism, often times hystamine. Non steroidal ant-inflamation drugs (nsaids) block the response and thus reduce swelling. You don't necessarily have to do that, much like a slight fever. It may give you physical relief because inflammation is painful, but you're slowing your body's best defense system."
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o32z8v | On the personnel list of music albums, “mixing”, “engineering” and “production” are listed as 3 different categories. What’s the difference between them? | Technology | explainlikeimfive | {
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"The producer works on the music itself (arrangement, lyrics, etc.), the engineer records, and the mixer mixes the recorded tracks. If a programmer is mentioned they are involved with sequencing and synthesis usually."
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o33ee4 | Why does stress often lead to weight gain? | Biology | explainlikeimfive | {
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"Stress releases the hormone cortisol which increases insulin levels which causes blood sugar to drop which increases appetite for sugary and fatty foods.",
"Some people cope with stress by eating/drinking more. This leads to a higher caloric intake and thus weight gain."
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o33qmb | Rubbernecking | Other | explainlikeimfive | {
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"Morbid curiosity. One can’t help but look at things like this as we have a morbid fascination and also need a life reassurance that we are the ones still alive and unhurt."
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o33xhx | Why is physical harm, like a slap on the back, more painful when you’re wet than when you’re dry? | Biology | explainlikeimfive | {
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"Under normal conditions, water isn't compressible, air is (this is why hydraulic tools are a thing). Also, water is denser, so it's harder to move out of the way of incoming force. These property have the effect of transmitting the force more efficiently. For a scaled up example of this principle at work, read about [Operation Crossroads]( URL_3 ). This atomic bomb test used decommissioned warships in 1945 at Bikini Atoll. Three bombs of identical yield were planned, to test ideal weapon deployment against a naval formation. The first bomb, shot Abel, was detonated 520 feet above the surface of the water. Here's footage of the [test]( URL_1 ) from the 1995 movie, '[Trinity and Beyond: The Atomic Bomb Movie]( URL_0 ). The second bomb was detonated 90 below the water, and, well... I'll let my man Bill Shatner [tell]( URL_2 ) you, he does it better than me. (Warning: Disturbing footage, live animals were used during the test). The same principle is why depth charges can sink a submarine without actually making contact with the hull of the sub. The pressure wave from the explosion is enough to crumple steel. It's also why falling from a great height into water is deadly. The water can't get out of your way fast enough, and the impact is therefore forceful enough to crush bones.",
"If you're wet, you're likely to be colder than normal. Your body responds by pumping less blood to your skin to maintain your core temperature. (vasoconstriction) So your skin cells are already being starved a little and as such your belly flop hurts a bit more."
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o33y0h | How are some infinities bigger than others? | I was watching Veritasium's video about math having a fatal flaw. He explained that if we make a set of all the numbers in between 0 and 1, then added one to the first digit of the first number and added one to the second digit of the second number etc, we would always have a new number. He said this proved that there were more numbers in between 0 and 1 than natural numbers. I was confused as to why you can't do this with natural numbers, and how that proved one infinity was smaller than another. | Mathematics | explainlikeimfive | {
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"The thing about math is, in some ways, it's like a game. The rules are whatever we say they are. Math is a human invention so all of its rules and definitions are whatever humans have come up with. So we have decided that, in math, we can have things called sets. Sets are just like collections of things. And sets can have sizes, which we define by the number of things in that set. But what about the size of sets that have an endless amount of things? Like the set of all natural numbers? Or the set of all real numbers? Well, in this case we have decided that to sets with an endless amount of things are the same size if you can create a rule that maps every single object in each of the sets on a 1-to-1 basis without missing any in either set. For example, take the natural numbers {0, 1, 2, 3....} Then take the even numbers {0, 2, 4, 6...} Clearly there are \"more\" natural numbers than even numbers, right? Because the natural numbers *include* the even numbers, plus more! Wrong. Given our rule, they are the same size because we can map them 1-to-1. Take any natural number, multiply it by 2 and you get a unique even number. Taken any even number, divide it by 2 and you get a unique natural number. 1-to-1 mapping. They are the **same size.** So we began to wonder if all sets with an endless amount of objects were the same size. Back in the day, a dude named Cantor came up with a rather elegant argument that showed that the set of real numbers is actually bigger than the set of natural numbers. He created a proof that showed that, no matter what rule you created to map the natural numbers to the real numbers, that there would exist real numbers not accounted for in that mapping. That there would always be and endless amount of real numbers left over. For that reason, we consider the set of real numbers as being \"larger\" than the set of natural numbers. Notice that, at no point have I used the word infinity. Unfortunately, \"endless\" *means* \"infinite\" and both of those sets we were talking about (natural and real numbers) are endless, so they are both infinite, yet according to our rules of math, the latter is larger than the former. Hence, \"some infinities are bigger than others.\"",
"> He explained that if we make a set of all the numbers in between 0 and 1 Not just a set, a list. It has to be well-ordered for the proof to work. There has to be a first number and a second number and so on. They can't all be in a disorganized heap. Remember, the point of the proof is to show that such a list is *impossible.* The argument is, no matter what list you present, his method will find a Real number 0 < x < 1 that isn't on the list.",
"> I was confused as to why you can't do this with natural numbers, If you take a natural number, and change one of its digits after the decimal place, you don't get another natural number. If you start with, say, 3, and change the ten thousandths place, you get 3.0001, which isn't a natural number— so it's not a problem that it's not found on your list of all the natural numbers.",
"First, we need to agree on what a list is. A list is just a way to assign a real number to each integer. There are a lot of possible lists, so just to make things clear, here is a possible list with an obvious rule of construction : * 1) 0.1 * 2) 0.11 * 3) 0.111 * 4) 0.1111 * 5) 0.11111 * ... And so on This is a particular list of real numbers between 0 and 1. It contains infinitely many items (one for each integer) but it certainly does not contain all the real numbers between 0 and 1. For exemple, it does not contain 0.2 Given any list of real numbers, there is a procedure (known as diagonalisation) that will return a real number that is not on that specific list. To illustrate the procedure, let's just take an example with a beginning of a list * 1) 0.**1**45869735... * 2) 0.2**3**3813848... * 3) 0.12**1**565351... * 4) 0.835**8**35833... * 5) 0.1535**7**3831... * ... Take the digits in bold (**1** **3** **1** **8** **7** ...) , add 1 to each digit (2 4 2 9 8 ...) , and create a new number by concatenating these new digits after a \"0.\" . This gives will give a number starting with : 0.24298... (Note that this procedure always gives a number which is a real number between 0 and 1) This new number cannot be anywhere on the list. Indeed, for any integer n, the n-th digit of that new number is different from the n-th digit of the n-th number on that list. Now, one can answer the following question : \"Can we make a list of real numbers that contains all real numbers between 0 and 1 ?\" The answer is NO. Because whatever the list is, there is always at least one real number that is not on that list, which is the one created by the procedure. This happens because there are far too many real numbers. Which means that even if you try to make an infinite list of real numbers, you will always miss some of them. So we translate that by saying that the infinity of real numbers is larger than the infinity of integers. You can not do the same procedure with a list of integers, because the object created by the procedure of concatenating digits is not an integer.",
"> I was confused as to why you can't do this with natural numbers Because then they're not natural numbers. Natural numbers *must* be integers. Let's try \"adding one to the first digit of the first number and one to the second digit of the second number etc\": * 1 is a natural number. * 2.1 is not * 3.01 is not The Natural Numbers are 0, 1, 2, 3... But there are infinite numbers between 0 and 1. And another infinite numbers between 1 and 2, and another between 2 and 3... The smaller infinities are called \"**countable**\" and the bigger ones \"**uncountable**\". Here's why: 1. Count the natural numbers: OK. 0,1,2,3,4.... It would take forever to count them all. But *if you had forever, you could do it*! 2. Now, count the numbers between 0 and 1, decimal numbers allowed: Alright. 0 ....um, *what's the next number*? Is it 0.1? No, can't be, then you'd have missed 0.01. Is it 0.01? No then you'd have missed 0.001... **If you try and count the numbers between 0 and 1, you can't even get to the first number past 0 in the list**, because no matter what number you say next, you'll have missed an *infinite* number of numbers before that one! When trying to list the numbers between 0 and 1, there's infinities *inside* infinities. An infinite number of numbers between each of an infinite number of numbers. It's **uncountable**. Listing the natural numbers doesn't have this paradoxical-explosion-of-infinities problem. There's just a \"regular\" list of numbers. It's infinitely long, but each step is well defined and not growing within itself."
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o3449l | How can the human ear (the brain, really) clearly discern more than one sound at a time? | I understand how sound is generated by pressure waves vibrating the eardrum. And this makes perfect sense to me when a single sound is generating that vibration. But when multiple sounds are vibrating the eardrum at the same time (like when listening to music with different instruments and vocals) how does the brain tease those differing vibrations apart so we can hear the individual inputs...as opposed to them mixing all together into one sound; The equivalent of mixing a bunch of different paint colors together and ending up with brown. | Biology | explainlikeimfive | {
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"ELI5: When sounds are added together a completely new sound wave is constructed that is an amalgamation of both waves. Think of waves in a pool. If you have one person making the waves at one end of the pool using the same amount of energy every time, then you'll see one set of waves moving across the pool in an orderly fashion. But what if two people are say... 10 feet apart and both make the same type of wave. Do you still see one wave in the pool? No. You see places where the waves add together, and places where the waves cancel each other out. This \"addition\" of both the waves together is actually a unique wave in itself. This is how sound works as well. Each individual sound \"adds\" together to make a new, unique, sound wave. Our brains are just good at picking out one sound in that sound wave. (Computers are also very good at it.) ELI'mOlder: What you want to look up is related to Fourier Transform. It's a math... thing... but you don't actually need to know the math. Watch this video from where I linked it (at 50s). URL_0 You only need to watch until ~2:00. A fourier transform is the way we program computers to separate sounds, or rather, the way we program the computer to be able to identify certain individual sounds in a sound amalgamation. Our brain does the same thing, and that's how we can pick out a \"single\" sound among an array of others. Also, the sound \"addition\" is also how a single speaker with a single moving component can produce many different tones at once (aka music!)",
"The same way your brain draws boundaries between the individual objects in a pile of objects sitting on a tables. The details of the process are incredibly complicated. So complicated, in fact, that our best computers running our best algorithms can't do it nearly as well. Basically, our brains evolved to be good at pattern recognition, including patterns in sound.",
"[Waves add up]( URL_1 ). Your ear drum is like a rubber duck floating on the ocean; it moves up and down with the big swells (bass sounds) and with the little ripples caused by the wind (high pitch sounds), at the same time. The surface of the ocean is \"big swells and tiny ripples\" all added up together into one \"complex\" wave. But the \"sound sensors\" in your ear are NOT in the ear drum, they're in the spiral [in this diagram]( URL_2 ) called the Cochlea. So what happens in the Cochlea ([more detailed diagram here]( URL_0 )) is the complex sound wave from your ear drum pushes through those bones into the Oval Window at the top, and vibrates the liquid in that spiral. The sound waves travel through that liquid in the direction of the arrows. And the sensor hairs (Cilia) in that Organ of Corti in the middle, they vibrate as the sound passes, and send those impulses to the brain via neurons. The trick though, is that the thicker hairs that detect bass sounds are at one end of that liquid spiral path, and the thin hairs that detect high pitch sounds are at the other end. So the sound frequencies (low bass vs. high pitch) get \"decomposed\" and picked up by separate hairs, and sent to the brain on different neurons. Your Cochlea decomposes that \"complex\" wave of all the instruments in an orchestra, by frequency. But it's your brain that makes sense of it all. Your brain is very good at recognizing patterns, and waves are patterns. Violin vs. drums vs. not just a person's voice, but words and *meaning* of the words, all of that is figured out by the brain, from sound frequencies. It's just what the brain does. Same with vision. Sound frequency is pitch (bass vs high pitch), light frequency is color. Your brain doesn't just see a splotch of different colors (different light frequencies), it recognizes objects, people's faces, *emotions* on those faces, etc. Pattern recognition."
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o3621v | How does somebody become extremely tall (over 6'3) even if both of their parents are short? | Biology | explainlikeimfive | {
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"This touches on the concept of *recessive genes.* In this case, both parents' shortness came from *dominant genes,* meaning they only needed one of two copies. The other copy was for shortness, but it wasn't expressed because you need two copies of a recessive gene. This person's parents were, however, able to pass on their recessive genes, and if one of their children gets both recessive genes (in the very simplest case, 25% of the time), they'll express that trait.",
"You have 4 potential factors at play. Firstly with genetics you need to look at the Grandparents, not the parents. The parents are passing on a mixture of their parent's chromosomes. Then you have to look at environmental factors especially nutrition. Poor nutrient during childhood could have caused the parents to be significantly shorter and good nutrition fixes that for the current generation. Mutation's can always occur resulting in minor (or more rarely not so minor) changes. Lastly hate to be obvious but could be one or both or parents are not the biological parent."
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o36l8y | How do rivers (such as the Thames in London) have tides? | The River Thames in London is a tidal river, it's not the only one in the world, but it's the only one I know of. How does a river which surely has a constant supply of water flowing into it have a tide? | Earth Science | explainlikeimfive | {
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"The whole river isn’t tidal, but the estuary is. Estuaries are where the fresh water meets the sea. The tides in the river are caused by the sea, not by the river itself.",
"The constant supply of a river is the bay, sea, etc. When that bay experiences high tide, there is more water in the bay. That water wants to go somewhere, so it proceeds downriver, and increase the water level in the river as well. The smaller and shallower the river, the greater tide it will experience. Eventually, the extra tidal water reaches a point a larger part of the river, where it has covered a certain area of river, and thus the extra water flow has less of an effect."
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o36nmy | when we have colds, why is the other nose dry and the other wet even though both holes are connected to one nasal pipeline | "I mean the nose holes" | Biology | explainlikeimfive | {
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"You only ever use one nostril at a time. This is so that when one gets clogged, you can switch to the other. With a cold, your mucus builds up faster, so it will block the active nostril quicker. That excess mucus causes you to notice when you normally wouldn't, but you always have a drier and wetter nostril."
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o36r5t | If carnivores secrete more acid than omni/herbi-vores, why can't they break down cellulose? | I'm guessing it has to do with some stuff about enzymes. | Biology | explainlikeimfive | {
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"Cellulose requires special enzymes **and** a long time. That's why grazers hve a very different digestive system."
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o3b6g0 | why is asphalt used on roads ? | Technology | explainlikeimfive | {
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"It's cheap (it's essentially just the crap leftover from refining oil) and much easier to apply than concrete.",
"Predominantly because it gives a very smooth finish. That's going to be quiter for the vehicles but also mean less repairs to the road. It also has the durability required and is relatively easy to lay",
"It's got grip so tires have good purchase on it. It can withstand a good amount of wear and tear before repairs are needed, it doesn't change consistency too much in high or low temperatures. It's weatherproof, it's super cheap. It's relatively safe to drive on even when wet. There are companies who are out there trying to sell \"smart roads\" which are modular and made of plastic panels which supposedly make repairs quicker but actually because it's plastic, repairs are needed almost daily compared to asphalt which needs repairing every few years. It will be a very long time before we move away from asphalt as a road surface",
"Awesome, one of the things I studied and do work with on the daily. Asphalt binder is relatively cheap as compared to cement. It is the excess “sludge” from refining crude oil while cement is made from burning multiple ingredients at 2000-3000 degrees F. Asphalt has a Viscoelastic property to it. Which means that as temperature changes, so does it viscosity, and elastic response to loads. When it’s cold outside, it is tougher and won’t flex as much. When it’s hot outside it will flex more. There are hundreds of not thousands of different types of asphalt binders. They are categorized by a method developed by Superpave in the 1990s. In Alabama they use a Performance Grade (PG) 67-22. The 67 is the high temp range in Celsius of the binder for it to not rut to failure. The -22 is the low temp range for it not to be too brittle at cold temps and crack. This PG can change based on the binder source. Colder states like minnesota might use a 58-28 to account for lower high temps and lower cold temps. If the right grade of asphalt is selected then you can prevent rutting and cracking. Rutting is when the road is too soft or the load from traffic is too high and the wheel paths sink down. This typically happens at intersections when traffic sits for longer periods of time. Cracking is when the road is not elastic enough to “relax” under loads and has to crack to relieve stress. Asphalt pavement can be paved in one continuous stretch, while concrete must have joints every 15-20 feet to allow the segment to expand and contract with temperature. It also can be driven on relatively quickly as compared to concrete which may need 7-14 days before trafficking. If the road is paved with a strong granular or asphalt base, only the top 2 inches needs to be replaced every 15 years or so. Unless cracking/rutting is bad from poor designing or unexpected truck loads. Asphalt pavement is recycled all the time. It’s relatively used in new roads taking up 10-40 percent of the mix depending on the state and project. Ask me anything else below this and I’ll get to it. Sorry for any typos!!",
"Its cheap, its almost 100% recycled, it gives good grip on the tires while providing a water barrier. Its not hard and stiff so it can adapt to changes without cracking."
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o3c6qi | When players are singing the National anthem during sports games, why do they always have children singing with them? | They’ve always got little children standing next to them, why? | Other | explainlikeimfive | {
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"Those children are called player escorts / match mascots. The idea probably comes from Brazil and was introduced in Europe in the 90s. There are a couple of ideas behind it. While some clubs charge money for the opportunity, the children also decrease the likelihood of people throwing stuff at the players. Posing with 'innocent' kids is also a clever move to paint the whole sport as a family friendly event and gives different campaigns like UNICEF a platform (jerseys) to promote their cause.",
"Because pro sports teams are usually very involved in their communities. For example, hockey teams will bring a kid out on to to the ice for the anthem so they can get a chance to stand on the ice in the big leagues beside some of their idols in front of 20,000 people. It will probably be one of the highlights of their life to stand on NHL ice beside their 'hero' for an anthem before a game. How many kids can say they led an NHL team out onto the ice in front of 20,000 screaming fans? It's literally just community outreach."
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o3dp8b | Why is the sea calm in the mornings? | So I've noticed that any time I've gone to the beach relatively early in the morning the sea is really calm. Practically no waves and really still. Is there any reason for this? | Earth Science | explainlikeimfive | {
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"There are two types of waves which can turn a flat sea into a rougher one - swell waves and wind waves. Swell waves can arrive at any time of day, but because wind waves are generated by the wind, they only develop when the wind begins to blow steadily. Since wind speeds are often low at night, and increase during the daytime, wind waves often die out during the night, leading to a relatively flat sea (perhaps with swell waves) in the early morning. During the day, the wind waves increase in size as the wind speed increases, leading to a rougher, more choppy, sea surface during the afternoon and evening. URL_0",
"Yeah during night it's colder and the sea and the land will have a similar temperature. When there is only a small temperature difference there will be less wind, and without wind there are no waves.",
"I don't know how much this effects waves but it might be interesting to you anyway: Close to the shore the wind usually forms convection cells. At day, the warm air from the land mass rises due to it increasing in volume and 'sucks' cold air from over the ocean towards the shore. This is that steady seabreeze you might be familiar with. At night the land cools down faster than the water since there is no sunlight hitting the land. Neither do they hit the ocean but water can collect much more heat and gives a little of it off at night. So, the air above the ocean gets heated up, rises and leads to the same circle (rather a cylinder spanning the shore) spinning the other way around with cold air coming from the landmass. In the morning the wind would thus normally come from the land (at least before the sun heats up the land again) Waves form due to wind catching on small irregularities on the water and from then on it catches on the small waves this wind has created. This can build up to the big waves you might know from the days. At night the wind came from the land and that could be why the sea is calm then. You could go out at night once and check if that hypothesis is true. It should be calm most of the night unless bigger weather phenomena interfere with this system. Also, you might want to look up convection cells yourself. Could be helpful to see a video of the process. There are also 6 major cells (3 on each side of the equator) spanning the whole planet leading to the steady trade winds the sailors used before motorised ships made the wind direction less important Edit: I just checked the other comments and found this to be the right answer appearently (yaye). I hope this longer explanation still helps someone out there thus I will leave it here anyway.",
"In surfing circles there is a thing called, 'Dawn patrol' which is basically the act of going surfing before work in the mornings. As someone who tracks waves, believe me there are waves in the morning just as there are in the evening.",
"In the absence of any large weather system wind you basically have two winds on the coast: Sea breeze and land breeze. Sea breeze is wind coming in from the sea and is caused by the sun heating the ground and happens during hot days. Land breeze is wind going out to sea and is caused by the cooling of the ground and happens during the night. So you have wind blowing out to sea at night. Also, wind causes waves by gently/violently pushing the top most layer of the water. So at night and in the morning you basically have winds that cause waves going out to sea but not coming in from the sea. During the day it reverses and you have wind and waves coming in from the sea.",
"The land and sea temperatures fluctuate differently because of the materials they're made of have different specific heat. Put simply, water takes a great deal more energy to raise its temperature than plants, dirt, and rocks. So, during the day, the land heats up faster, and this creates a high pressure zone which generates a seaward breeze. In the evening, as temperatures fall, the reverse happens, and you get a landward breeze. Since wave energy is affected by winds, that accounts for your cyclical changes in their behavior. In many coastal communities, these temperature and pressure changes produce evening fog, as the evaporated water through the day which had been pushed out to sea from the seaward breezes, and when those wind patterns shift and air temperatures drop, the water condenses out of the air, and the wind blows the how misty air inland.",
"Sailboat captain here: this is a big deal for us, and is a big part of how we get from point A to B sometimes. Worth noting that its a land phenomenon and doesn't happen in the ocean once you get out a ways. The \"sunrise glass-out\" (also happens around sunset) is a bubble of warm air coming off the land, it can extend for miles if the coast is right. It kills the normal wind, so if you have to move a boat upwind you can motor at sunrise/sunset and make great progress. Particularly useful off Cuba and Hispaniola if you hug the coast.",
"Waves come from wind, mainly. Wind comes from temperature changes. Temperature changes come from the sun.",
"If you live in a temperate area, then the winds might be calmer at night where you live. That could explain it. It could also be that you don't go to the beach in them morning when it's stormy. So it isn't necessarily so. Do you go to the beach early in the morning on stormy days? Depending on where you live you might have a calm sea just in general based on geography. I lived by the sea for years. Some mornings it's calm, and some it's not. Seas are not calmer at night in the tropics. They might be in temperate areas. Trade winds in the tropics are effectively constant and ocean wave trains are driven by these winds, so there will be waves breaking continuously night and day. The storm patterns in the area are also a factor."
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o3gyuz | What makes thermal wear warm? Why is often polyester made? | Technology | explainlikeimfive | {
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"Good thermal wear works by a combination of capturing and holding the body heat while transporting moisture towards the outside.",
"It traps a lot of air. Air is a very bad conductor of heat i.e. a good insulator. Generally thermal insulation is all about trapping as much air as possible, using as little material as possible. That’s why down is such a great material for winter clothing. It’s very light, yet expands to considerable size. The advantage of “synthetic” fibres like polyester is that they don’t clump up when wet and don’t trap a lot of water. But for insulation it’s generally a good idea to have some wool (or down).",
"A good thermal layer wicks the sweat away from your body keeping you dry, having this layer is extremely important especially if you do any winter related sports; if you were to wear a cotton shirt and go say snowshoeing the cotton would absorb all your body moisture and sweat eventually once you open your over coat that cold damp shirt will freeze. Not sure what makes polyester the best but I’m guessing because it’s a man made fabric it was designed for that purpose? Also sometimes you’ll see a thermal lining inside jackets it looks like a shiny metal layer of fabric it bounces heat back towards you so you’re always warm"
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o3h59t | what causes antlers to become larger as a deer ages, even though they're shed and regrown every year? | Biology | explainlikeimfive | {
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"Part of it is genetic. The antlers is designed to fork more as the deer ages. But it is also based on how much stored up energy the deer have. The bigger the deer the bigger their antlers will be regardless of how many forks they have.",
"Interestingly, the antlers wouldn't be able to grow as the deer ages if they _didn't_ shed them. Growing antlers are covered with a thin layer of tissue called velvet. The antlers themselves are bone, and like all bone are created by cells which have to be inside the body to function. Velvet provides nutrition and bloodflow to the cells growing the antlers. But of course, all that fragile velvet couldn't withstand the combat that antlers are used for. So it is lost when the antlers mature, leaving only dead bone. The problem is, dead bone can't grow. So a deer that didn't shed and replace antlers would be stuck with the same ones it had in the first season. Antlers really are incredibly _weird_ when you think about it. Anyway, getting stuck with your original antlers would be a problem because, as you note, antlers get larger as a deer ages. And big antlers let deer get more mates. So being stuck with your first set is bad. But to get back around to your actual question, deer antlers are really expensive to grow. They are the fastest growing bone in any mammal, and they require lots of calories and _loads_ of calcium. On top of that they are pretty heavy. So small deer just don't have the capacity to produce big antlers. As they get older and larger and have bigger reserves of energy and calcium, they can support larger antlers. More resources means antlers can grow faster during the growing season meaning they wind up being larger.",
"I actually read about this a few days ago! Deer antlers usually first come out after a year, and they're pretty small since a lot of the calcium goes towards bone growth. As the deer gets older and matures (around 5-7 years) they'll need less and less calcium for bone growth and more of it is used for growing antlers. After the 7 year mark is when they start getting those giant antlers. That being said the maximum size for antlers is somewhat determined by genetics so it varies from deer to deer, some mature deer will just never get massive antlers.",
"Just wanted to add that they do get bigger every year until they reach middle age. They start to go down in size after middle age, except for the base of the antler. The base always gets bigger. You don't see this in the wild, because most deer don't live past middle age in the wild. Also, antlers are like finger prints to the animal. They always grow the same shape for that deer. URL_1 URL_0"
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o3hfhn | Why do we loop rockets around Earth instead of shooting them straight up? | I get that rockets need to go sideways if they are putting satellites into space, because those satellites need a certain amount of velocity to maintain an orbit. But why do we loop rockets around the Earth if we are sending something out into space, e.g. to the Moon? Why can't we just point the rocket at the Moon and shoot straight up? | Physics | explainlikeimfive | {
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"It's called a Hohmann transfer to get to the moon or other orbital bodies. This is the most fuel efficient way to reach escape velocity with a targeted trajectory leading to intercept. If you go straight up, it would take immensely more fuel to to create a seriously large elliptical orbit which won't even get you to the moon. Gravity is everything and the affect of it on orbits is real... If you are really interested in learning more.. think about playing Kerbal Space Program.. will teach you all about orbital mechanics, delta v and fuel management. It's amazing to learn with.",
"I'm a moron and might be half remembering this, but I think it has to do with fuel efficiency and how orbiting works. To stay in orbit, you've got to go sideways, whatever you put up is essentially always falling back down to earth so you need to keep it going fast enough that it continually falls over the edge. Plus, orbit allows time for adjustments and making sure everything is good to go, space travel is dangerous and complicated. Then, when traveling between bodies, you want to make sure relative positions are set up so you're making the shortest trip using gravity to sling you out.",
"> I get that rockets need to go sideways if they are putting satellites into space, because those satellites need a certain amount of velocity to maintain an orbit. But why do we loop rockets around the Earth if we are sending something out into space, e.g. to the Moon? Why can't we just point the rocket at the Moon and shoot straight up? Accounting for your initial vector and the movement of your target, basically directly going on an intercept course... you could *totally* do that - if you had a rocket with arbitrarily large thrust and arbitrarily large fuel reserves! The kind of fledgling space travel conducted by humans in the immediate vicinity of our home planet is not really limited by travel time or distance, it is limited by the physical and chemical restrictions imposed by our current level of engineering. Rocket motors that do what you envision do not exist. Engineers have to desperately scrounge for every last bit of efficiency that can be wrought out of the limited fuel reserves that contemporary space craft are physically able to carry in relation to their payload. That means abusing every possibility of a [gravity assist]( URL_0 ), that means launching rockets from the equator, that means launching rockets into the direction of the Earth's spin, that means timing your [gravity turn]( URL_1 ) properly and that means *not going straight up*.",
"Because of gravitational forces, the moon is constantly circling the Earth, as we are the sun. If you were to point at the moon and launch, you'd probably get to where the moon was but not is. So you have to coordinate where the moon is moving to, and use the Earth's gravity as a catapult, basically. Edit - this may help [ForYou]( URL_0 )",
"It's about fuel. If you didn't have to worry about fuel, you could just go from A straight to B like ships in The Expanse show. But unfortunately we are very limited by fuel, so we have to use Earth's gravity to 'swing' towards other bodies, only burning fuel at critical moments similar to how you push with your legs on a swing only when you're at the closest point to the ground."
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o3hkcc | Why do the televisions in the store always have amazing pictures but when you get home and pop in your favorite movie...? | Shopping for a new TV, this is mild infuriating. | Technology | explainlikeimfive | {
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"TVs typically need to be calibrated after you pull them out of the box. They look great in the store because they are specifically calibrated to make the demo video used to show off the TV look as good as possible. However, those demos don't translate to every day TV, movies, etc. I usually Google the make/model of my TV plus the key word \"calibration\". You will see several professional review sites that will usually share the recommended calibrations or calibrations they used to test. Now, if multiple sites are saying the same thing for a certain setting, that's what you do. If they vary on another setting, go with the one you like the most. This will give your TV a good baseline configuration and then you can make adjustments from there. Hope this helps!"
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o3ilgv | Why do our eyes blink when we try not to blink? | Biology | explainlikeimfive | {
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"To clarify; are you asking why the need to blink becomes greater when we try not to blink? If so, blinking is a reflex, much like breathing. Your body does it without realising. It’s to keep your eyes from drying out and keep dirt out of them. If you force yourself to not blink the urge to blink increases as your brain wants your eyes to not dry out."
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o3j2hh | Why do we sometimes get a feeling of falling when really close to falling asleep that wakes us up? | Like you know when you’re already about to fall asleep and then you just randomly get this feeling that you’re falling and you instantly wake up in fear? Why does this happen? | Biology | explainlikeimfive | {
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"These are called \"Hypnic Jerks.\" They occur when: * You have **anxiety**. As your body falls asleep, your brain remains awake. Your body may send out an alert, because it thinks it's falling. * You've taken **stimulants**, like coffee. Your brain is falling asleep, and this chemical wakes you back up abruptly. * You've **exercised** too recently. Your body is still in go-mode! * Your tree-dwelling **ancestors** may have received these jerks to keep them readjusting as they sleep high up in trees!",
"So I see some general reasons as to WHY it happens, but not what is actually happening. A hypnic jerk occurs when your brain, which is still in \"awake mode\", senses a sudden relaxation of too many muscles as your body enters \"sleep mode\", similar to what happens when falling, your muscles suddenly aren't supporting you while in free fall. Sometimes we'll even have a dream that we trip or something as a way of our brain providing an explanation for it",
"Your brain doesn't fully realise that it's asleep and notices that your muscles aren't moving so it makes them jolt to make sure you're still alive",
"Humans are funny; at night, we just lay down and pretend were asleep until we actually fall asleep lol",
"Our distant ancestors used to sleep in trees. Falling out of them was a real danger and we needed to wake up fast if it happened. Our brains are still a little hyper viligent in this regard.",
"From what I've had explained by my nurse friend, your brain sees your heart rate / blood pressure dropping off and not knowing if you are dying or not, brain gives you a small adrenaline boost save your life or something. I know I'm probably explaining this badly. But yeah small dose of adrenaline"
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o3jml9 | I’ve always understood that computers work in binary. But programming languages use letters, numbers, symbols, and punctuation. How does the program get translated in binary that the computer understands? | Technology | explainlikeimfive | {
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"Most of the answers here are correct, but it's also important to note that all the letters, numbers and symbols you enter with your keyboard are also in binary. Each character is represented by a number, for example the uppercase letters A-Z are represented as the numbers 65-90. These in turn are represented in binary.",
"The answer actually depends on what programming language you're using. In compiled languages like Java and C/C++, the code gets transformed into a computer runnable executable after you write it, which consists of binary instructions. This transformation is a process called \"compilation\". By far the biggest non compiled language in use today is Python. In python, the code actually gets turned into binary on the fly as you run it. Quick edit for clarification: A compiler can mean multiple things. If someone is talking about a Java compiler, they are generally referring to the entire pipeline that converts Java into machine code. However, if someone is talking about the compiler stage, they are probably referring to the individual part of compilation called \"the compiler\", which actually is not the part that creates binary.",
"Letters are converted to binary using some [character encoding]( URL_4 ) . This is a kind of convention that says how a character is written in binary. This has changed through the time. Nowadays many systems use [UTF-8]( URL_0 ) Integer numbers are also converted using different methods. The most popular is [Two's complement]( URL_2 ) . With 2 sub-variants [Little-endian and Big-endian]( URL_1 ) . Real numbers are now mostly converted using one of the [IEEE 754]( URL_3 ) floating point formats",
"It's all binary in reality. The letter 'A' in this message is simply character #65, which is `1000001` in binary. And in old computers there's literally a table where characters are drawn, again in binary. With a 1 where a black pixel would go, and a 0 where the background would be. Even when dealing with compilers you're taking one kind of binary data in, and producing another kind of binary on the output.",
"It would be fun to do a deep dive on computer languages as an ELI5. Let's give it a try! Computers, at their lowest level, are electrical circuits. Complex ones. Very very complex ones. But what's neat is that we've made these circuits into interesting patterns where we can load a 'program' into it and it performs math and logic and interacts with inputs (keyboard, mouse, internet, etc) and outputs (monitor, speakers, internet, etc). Since everything is an electric circuit, everything is stored and processed as 'binary'- 1s and 0s, meaning 'on' or 'off'. Electricity flows or doesn't flow. (Often it's 'high voltage' vs 'low voltage' but the idea is the same). That is where the idea that programs are binary comes from. Everything on a computer is binary! And when we load a program onto the computer, we're just turning circuits on and off very quickly in specific patterns so that the computer (the processor) does the things we want it to do. But it turns out that writing programs in binary by hand is really really hard. And we programmers are, usually, the laziest people you will meet. Do you know what happens when you give a lazy person a tedious and difficult task? We find ways to make it easier. And so we came up with very slightly higher level 'languages'. Instead of raw binary, we would make 'words' that represent specific binary patterns. Move this bit of data into this CPU register (a memory spot)! Run CPU operation ADD! It made things really a lot easier. Except then we started to have bigger, more powerful computers and we needed to make bigger, more complicated programs. Lazy programmers to the rescue- we made higher level languages that map more English-like words down to Assembly language and binary. This pattern keeps repeating. Programming languages today are often very readable, sometimes very close to being English. There's a whole field of study in computer science of how to make the best computer languages, and how to make them compile down into the fastest, most efficient binary programs. Source: Bachelors of Computer Science, plus ten years as a software developer"
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o3k6qt | why does that finger trick for nine times tables work? | Ykno like you put the first finger down and that’s what 1x9 is, second finger leaves one finger on the left and eight on the right meaning 2x9 =18and so on... why does that work? It’s so perfect it’s weird | Mathematics | explainlikeimfive | {
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"Nine is one less than ten. Each time you count up another nine, another way to think about it is that you are counting up ten and subtracting one. Thus, you add one number to your left hand for the ten, and then remove one number from your right hand for the minus one. Edit: I think I'm thinking of a different hand trick, but basically all tricks related to the 9 times table work like this so hopefully this still helps.",
"One way to think of it is 9=10-1, so to get to the next multiple of 9, you add 1 to the tens place and subtract 1 from the ones place. This is what you are doing when you move to the next finger. You put up the finger that used to be down (add 1 to tens), and put down the next finger (subtract 1 from ones, since this finger used to be part of the ones place). For fun, this also works with any base. For example, if you use just 1 through 5, you get the same effect using one hand for multiples of 4, since 4=5-1. If you put down the first finger on the left, you get 1\\*4 = no fives and 4 ones. If you put down the second finger, you get 2\\*4 = 1 five and 3 ones. This corresponds to 8, since 1(5)+3(1)=8, which is the correct answer to 2\\*4. Sidenote: It took me a moment to realize you weren't saying you had 8 fingers on your right hand.",
"Multiplying some number by nine is actually the same as multiplying that number by ten and subtracting an equal number of ones. If you want to do 4x9, that’s the same as 4x10 - 4x1 You have ten fingers, so when you put down one of them, you’ve done that second step. If you put your fourth finger down, you have six fingers on the right, because 10-4=6",
"In base 10 it works for the nine times table. In base 16 it works for the 15 times tables, but you have to use 6 imaginary fingers. In binary it works for the one times tables. It also works for 999 times tables in base 1000 which is actually usable but not useful. To calculate 57 * 999, you do 056 for the first base 1000 \"digit\" and 943 (1000 -57) for the second digit, giving 56943. Seems like the pattern is for base n it works for multiplication by n-1 That's not actually an answer for why it works but it at least demonstrates why multiplying by 9 is special in base 10."
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o3km4k | How does glow sticks works | Its maybe a dumb question but I always wondered how does glow sticks work I made some researches on google but I can’t figure it out. So explain like im five...? | Chemistry | explainlikeimfive | {
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"Inside the glow stick is a chemical. Also inside is a glass cylinder filled with another chemical. Neither chemical glows. But, if you bend the glow stick and break the glass cylinder, the two chemicals mix, causing a chemical reaction that slowly gives off light.",
"The glow stick is actually two sticks! The bigger, outside stick holds a special chemical that glows under special lights (like black lights) and another special chemical that wants to break apart. The smaller stick that is inside the bigger stick has hydrogen peroxide, which you may have at your home to use on a cut to prevent infections. The smaller stick is made of glass, so when it's broken, the hydrogen peroxide reacts with the chemical that wants to break apart. When that reaction happens, it makes light like a blacklight would. That light makes the chemical that glows under blacklight, glow!"
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o3krqt | - why is airplane internet so unstable? | Technology | explainlikeimfive | {
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"Oh wow. This is my job! So imagine every piece of information goes through hoops to get to the server and back to you. On an airplane when you fly above the clouds the information must go through a satellite, and the more hoops there is to jump the more possibilities for something to go wrong."
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o3kwxs | Why does human species look more or less the same, even among different races, while there are so much varieties in other animal species? | Biology | explainlikeimfive | {
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"There is a theory that visual diversity is so low because at one point during human evolutionary history the population was reduced to 2% of what it was. This would drastically have reduced the visual variety, regardless of the population rebuilding.",
"> there are so much varieties in other animal species? Generally, there aren't. In most species which haven't been deliberately selectively bred by humans, individuals all look pretty much the same. Think about the range of human skin and hair colouring, for example, and think about how many different colours you've seen in polar bears or lions or bumble bees. In many species - and I'm thinking particularly of birds here, but I expect it applies more widely - tiny differences in colour or shape can be used to reliably identify which species an animal is.",
"Like dogs and cats? Partly because we selectively breed them. As humans, we made an effort to breed dogs that had particular features to try to accentuate those features. Over time, this has resulted in breeds of dogs that look less and less like each other. Historically, this has happened a bit with humans too, where certain subgroups are more likely to breed with each other (for example, European royalty, or people of a particular faith), but we're much better now at intermingling."
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o3kzio | How is the average earth temperature calculated? Where are the values coming from to calculate the average? | Earth Science | explainlikeimfive | {
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"There are weather stations, small and large, all over the world. You can even set one up in your house and have it report to the official weather watch systems over the internet. Almost every country has their own military weather networks. Then there are civilian weather networks. That's because weather is vitally important to human survival. Been various oceanographic institutions and national actors have weather condition buoys out at sea. There's also weather satellites that read the infrared conditions, ie the surface temperature and air temperatures, over vast swaths of land. The world is almost choking to death on weather data because weather affects everybody all the time. So when doing a particular study one looks for a continuity of data from various sources to make conclusions about various regions. There are weather archives run by all sorts of organizations and governments that you can just download for online. Now the older weather data, like from 100 years ago, used to be in big books with summary pages and stuff like that. But a lot of that if not most of it has been transcribed into online databases over the years. The age when we had to write shit down several times a day to monitor the weather has long since passed, but that old data is still out there."
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o3l14t | If hot air rises, why does it get colder as you increase altitude on earth? | Earth Science | explainlikeimfive | {
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"As hot air rises, it expands. As air (or most other fluids) expands, it cools down. So air that was hot at ground level will expand an gradually cool as it rises through the atmosphere.",
"Because the density of the air is reduced with altitude. There is \"more space\" between each air molecule. Temperature is equal to pressure, and lower density equals lower pressure. Hot air will be able to ascend a limited distance before the mass of air expands and the molecules scatter more and more."
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o3l9wl | what makes sushi safe? | With all meats, you need to cook them to a certain temperature to kill bacteria like salmonella. How do sushis dodge this problem with just washed, raw fish? | Biology | explainlikeimfive | {
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"In general fish used for sushi is frozen immediately after being caught, killing the bacteria. URL_0",
"generally speaking, the things that make meat unsafe to eat raw, such as ecoli and salmonella, are not present in fish. Additionally, fish is often frozen before being used, which can kill parasites or worms that can be found in fish.",
"In addition to what everyone else has said, it is a common misconception that sushi = raw fish. That's Sashimi. Sushi is defined by the rice used in the wrapping, so the fish inside of sushi absolutely can be and often is smoked or cooked, and ALWAYS frozen beforehand.",
"We don’t normally get sick because of safe handling standards. Yes you can get sick from sushi but it’s more than likely the place you got it from or the production chain were not following safe standards. Same with raw hamburger, perfectly safe to eat if the animal was slaughtered properly and no contaminates came in contact during production.",
"People alao eat raw beef, raw chicken, raw pork fat, etc. Bacteria is not normally inside the meat, but outside the animal or in their guts. Chicken in the US is processed in such a way that salmonella from the bird's guts gets all over the carcass. Chicken prepared carefully is sometimes served as sashimi. Fish for sushi is deeply frozen as soon as it is caught. This kills the parasites (worms) that can be found in ocean fish. When they cut up the fish, great care is taken to not contaminate the flesh."
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o3lbnz | How do built-in random functions work in programming languages? | Many programming languages have built-in (pseudo)random functions. How does the algorithm for those functions work? I mean, how can you create an algorithm that picks a random number and how does the picking process work exactly work if it's just pure math? What would the mathematical formula look like for such function? | Mathematics | explainlikeimfive | {
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"Any random function in a programming language is only pseudo random as you say. You give it a 'seed' and it manipulates the seed to give you a number that is pretty random for most purposes other than cryptography. But it will eventually start repeating and the number produced is deterministic (i.e., given the seed and the function, you can predict your 'random' number). So it doesn't 'pick' a number as much as just produce an output given an input just like any other function. If you see the full list [here]( URL_0 ), you'll see they are all just normal functions that take some input and produce a 'pseudo random' number as output. Beyond this though, cryptographically secure random numbers must come from some 'true source of entropy' which exists outside the digital system. You could sample say the voltage on an open wire or read the temperature of the system super accurately to say 10 decimal places and use the lower few numbers as a random number. In practice though, this number is then used as the 'seed' to then be processed to produce a 'true random number' that you can use for secure transactions and such."
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o3lvg4 | Why does the egg shell "run away" from you while trying to pick it out from eggs? | Biology | explainlikeimfive | {
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"text": [
"the albumen that's between your finger and the egg shell piece is thick and sorta viscous, so when your finger moves through it, it continuously pushes it up towards the shell piece momentarily before it makes way for more albumen",
"Pro tip: If you need to pick a piece of egg shell out of the egg white, use one of the half of the shell as a scoop. It will cut right through the white and not push the shell piece away."
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o3lxgc | What exactly is radiation and how can we visualise it? | Physics | explainlikeimfive | {
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"There are a couple big types of radiation. The first is non-ionizing (radio waves, sunlight, stuff like that) that has less energy and can't knock electrons out of their orbit; they can still excite cells and matter with enough exposure to generate friction and heat (look at sunburns, or what happens to someone who stands too close to a high-powered radar antenna when it goes off). The second is ionizing radiation, which are higher energy waves (x-rays and gamma rays) and physical particles (alpha [two protons and two neutrons] and beta [high-speed electron or positron]) caused by radioactive sources like radon or uranium or plutonium, that *can* remove electrons from atoms. That means they are also powerful enough to deal damage to the DNA in cells and that can kill cells or cause mutations that lead to illnesses like cancer or worse at high enough exposure levels. As far as \"visualizing it\", do you mean through actual technical means or just in general what would it be analogous to?"
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o3mem2 | How can lightning split open a 10ton tree, setting it ablaze, yet most people that are struck will survive? | Ive seen several trees reduced to a burning splintered mess in my life, yet when my uncle safaried in the congo and got struck, all he was left with was some hearing loss and pocket full of welded change. | Physics | explainlikeimfive | {
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"Humans are more electrically conductive then trees. So the current have an easier time going through a human and less energy is converted to heat. And when human cells gets flash boiled the surrounding cells is able to squish out of the way without getting damaged while a tree have very hard cell structures that gets turned to splinters under the same force. The fire is also different as humans do not burn in open air while trees do. So if you are going to be struck by lightning, be a human and not a tree.",
"Conductivity, our body is way more conductive than wood, the lightning will travel fast through the body, the point of entry and exit will sustain the most damage; wood is not that conductive so all the energy will make it split because it can't pass quickly enough. This might not be the most exact explanation but I believe it's in the ELI5 range.",
"Trees are more combustible than the human body. It’s really difficult to set a human body on fire because of the water content. When hit by lightening, the energy will pass through the human body and dis-regulate the central nervous system which can be fatal, but because the strike isn’t sustained for a long period, it doesn’t cause the water in the body to evaporate and so there isn’t a fire. A person could have a heart attack because the normal electrical signal that tells the heart muscle tissue to fire (contract) is interrupted. If the electrical charge interferes with the brain’s neurological function, that can also cause death. But usually, one large jolt won’t kill you unless that jolt affects the aforementioned systems. A dry tree is more likely to catch fire than a wet tree. The size and weight of the tree is inconsequential."
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o3mpl8 | Random, short lived ringing in the ears… | Biology | explainlikeimfive | {
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"So, any time you hear a sound that isn't a physical sound, it's called tinnitus. There can be a bunch of different reasons for it. Some are that there's something wrong, others are just about what's going on in the moment. Our ears require the pressure inside them to be the same as the pressure outside, on either side of the eardrum. To do this, our ears pop. This lets air flow through a tube from the back of your throat/nose, the eustachian tube, to balance the pressure. Sometimes, this takes a bit longer than usual. Maybe you're a bit congested with a cold. When this happens, we can hear a bit of a ringing sound. This is just tinnitus. The reason is that the sound can't properly get through your ear. Your brain tries to compensate by turning up the volume, but it's like turning up the volume in the car when there's a bad radio signal. You just get more static.",
"For me, those times where sound is very muffled *most* of the time is caused by a buildup of earwax that has essentially blocked the entire ear canal. It doesn't necessarily take a lot to do this, just enough to block the opening and block sound. It could also be blocked due to sinus congestion, like when you get a bad cold and then can't hear out of one ear for a few days. Sometimes tinnitus can be temporary or in my case permanent, with several different ways that it can occur. For me, growing up on/around USAF bases (loud planes for 18+ years) I'm sure is part of the reason, but I also used to get ear infections growing up which definitely contributed to my tinnitus. I just tend to ignore it / tune it out by having other background noise to listen to. If I accidentally focus on the ringing it will get a lot louder, and it makes me hate complete silence (because then the only thing there is to hear is the ringing). In the end my tinnitus is caused by damage to my ears growing up. I can mask it or ignore it, but it's always there."
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o3myrt | DNA Base Pairs | I am satisfied that DNA exists, but how do we prove that base pairs exist? I was reading about their discovery and was not satisfied with the explanation so I was hoping someone could explain it. And bonus question, how do we know their physical size? | Biology | explainlikeimfive | {
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"Chemist here, not biologist, so would appreciate if a biologist could confirm/expand on this: Very simply, we can extract and crystallise DNA. Then we can shoot x-rays at the crystals and look at how the x-rays bounce off (diffract) this is a method used to determine what the structure of a crystal is, called X-ray diffraction, commonly used in materials science. By looking at the crystal structure we can deduce information about the structure of DNA (for example existence of base pairs). Today, we are also capable of cutting out individual bases from a strand of DNA using special enzymes (like scissors that will only cut at a specific place). These can be further analyses by NMR or chromatography (see below) We are even capable of \"writing\" DNA with a specific sequence, which is being tested for high-density data storage. NMR: Nuclear Magnetic Resonance, put something in a very strong magnet, then take another, weaker magnet and (literally) shake it around close to your thing. Then measure how the magnetic field inside the strong magnet changes, depending on how fast you shake the weak magnet. Liquid Chromatography: Put your stuff in one end of a very long tube with a specific material on the inside (called the \"stationary phase\", typically silica) and pump some fluid (can be pretty much any fluid, depending on the experiment) through. Then measure how much light is absorbed by the fluid that goes out. If your stuff is a mixture, and you use the right fluid/stationary phase, you will see increased absorption whenever one of the components of the mixture leaves the tube. They will take different amounts of time getting through the tube depending on their chemical properties. Gas chromatography: Same thing, but do it with a gas and burn the stuff as it comes out and measure how hot it burns. The challenge is using a fluid/gas/stationary phase that makes the mixture separate. TL;DR: We can cut up the DNA and analyse it with various methods. We can also measure the structure of the DNA before we cut it up with other methods. Edit for the bonus question: That is part of the information we can (probably) get from XRD, I'm a materials chemist, so I'm not too familiar with XRD of organic molecules, but I would bet that's how it's done."
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o3n011 | What’s the difference between high quality and low quality speakers? What’s actually happening that causes one speaker to sound super crisp while another speaker sounds muffled? | Technology | explainlikeimfive | {
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"The main measurable things are frequency response, distortion, resonances, and dispersion. Bad speakers have a poor frequency response so certain frequencies are louder than intended, such as boomy bass or high pitch noises. This is very hard to achieve and requires digital processing/equalization to be near-perfect. They also have high distortion. This would be like if only bass is supposed to be playing but instead you also get higher frequency noise that shouldn’t be there at all. Resonances cause very specific frequencies to be very loud and also they keep ringing even when the sound should have stopped playing. Finally, speakers should emit sound in a fairly even distribution in front of the speaker (this is very simplified) so things sound about the same whether you are sitting directly in front of the speaker or to the right/left/above/below it. Bad speakers typically don’t do this well.",
"Acoustic engineers can tell you the answer is not simple, and I ain't even one of those. The entire system works together to produce sound. The material, size, and angle of the cone; the weight and strength of the magnet; and the size, structure, and resonant frequencies of the cabinet (among other things) all play a role in the overall dynamics. You could have a perfect cabinet for one cone, and it could sound either bright or muffled with a different cone, ect. tl;dr i dont think this can be explained to a 5 year old."
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o3n6qb | When you brake in a car, where does all the kinetic energy from the wheels go? | Physics | explainlikeimfive | {
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"Traditional braking: friction is the mechanism but that means heat. Specifically heating up the brake disk/pad Regenerative braking: a battery! You're basically switching an electric motor over to an electric turbine/generator so the energy is being used to charge the battery."
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o3o4ve | how am I supposed to know when is proper to use a number, like 15, when writing or write it out like fifteen, especially for college papers? | Other | explainlikeimfive | {
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"What I learned was write out if it's under 10, numbers over (both can happen in the same sentence). Aways write it out when it begins a sentence.",
"It all depends on the context surrounding the number. The \"general\" rule is to write out numbers using alpha until you get to 10. After that, use numerals. Here's a good page about when to use what: URL_0"
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o3p7j8 | Why is circular polarization preferrable for satellite communication? | I know that electromagnetic radiation behaves like a wave, and that it is also a stream of particles. And I know that its polarization is the geometrical orientation of oscillations, like for example if you had a rope and you swung it in a circle, that would make it "circularly polarized". But I don't know why it is better to use circular polarization for sending signals through space? Can somebody please explain why this is and how it is actually achieved? | Physics | explainlikeimfive | {
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"with linear polarization, the relative orientation of receiver or sender is important. Of one (or both) are spinning, you will go through phases where you can't detect it. With circulars polarization, relative orientation doesn't matter anymore. Plus, it is much easier to filter out your own reflections when waiting for responses."
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o3q1ue | How do ice hotels exist? | I am floored by their existence. Especially the ones with fireplaces within them and also the beds. Surely, touching ice would a: result in freeze-burn and b: melt the surface layer of ice so it is constantly wet. This means lying on a bed made of ice, would make your clothes damp and you would freeze. I know very little science, please help me understand this, thank you | Earth Science | explainlikeimfive | {
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"First, for why ice hotels exist, theyre and interesting and rare experience so people go to them just to experience the ice hotel itself, not because they expect a nice comfortable stay while traveling for work. Its the same reason hotels with water parks exists, it is an entertainment destination. Second, yes, touching the ice for a long time would hurt your hand and lead to frostbite. The inside if ice hotels are usually kept around -5 C or min 20s F, so the ice never melts from the air temperature, and your body would lose all its heat before it significantly melts the ice. Third, while the structure of the bed itself, like the bed frame, is made out of ice, you do not sleep directly on the ice itself. Between you and the Ice is typically a mattress of some kind if not at minimum a waterproof covering. Also Ice hotels aren't a year round thing, typically they melt in the spring and start to get reconstructed in the fall, also, ice hotels aren't typically ALL ice. Most have heated attractions as well as the ice attractions. There may be both an ice bar and a heated bar, there are the ice rooms and normal heated bedrooms, ice sculpture attractions as well as things like hot tubs and saunas. this varies from location to location, some are purely ice that aren't open year round, others are more like ICE Additions added to the normal hotel during the colder months."
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o3qei0 | What causes body shrinkage? E.g.: why is the queen so much shorter now than when she was younger? | Biology | explainlikeimfive | {
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"Technically, the queen has been trading her height for immortality. Time is slowed down by an increase in gravity, so she has agreed to greater pull on her bones in exchange for increased lifespan.",
"In a single word: gravity. Check out Scott Kelly the astronaut. Grew 2 inches in space I think."
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o3ryzd | How wild plants and trees can grow so big and resilient with almost no care and potted plants need costant attention? | Biology | explainlikeimfive | {
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"Wild plants are in the ground with constantly replenishing nutrients and circulation, and it has the soil and any bodies of water to pull the water from. Potted plants are separated and have no community soil to get nutrients and water from so they need to be cared for in order to get them.",
"A wild plant, by its very nature and existence, is perfectly suited for the location it’s thriving in. It’s a little bit survivorship bias and a little bit survival of the fittest. A potted plant has at the very least been yanked out of where it feels most comfortably and is frequently the product of decades, or even centuries, of selection for charactistics that are **not** optimizing for survival in the wild, but rather appearance, or fruit production, or flavor, or any of the other numerous characteristics humans select for.",
"What you're seeing has partially to do with the fact that you've taken a plant away from its own resources. Imagine, for a second, that you were picked up, and plopped somewhere in the arctic. Whoever put you there would need to do a lot of work to keep you alive. * You would not be able to work your normal jobs, so you would have lost an income and a way to spend your time * You would need to have food and heat provided for you, as you cannot follow your typical survival strategy of \"pay electric company for money and turn on heater\" or \"drive to store buy food\" * You would not be able to create your typical social support network * Your medical system would be completely inaccessible to you Now, let's apply this to plants. Note this is not 1:1 * Normal places where soil nutrients can be found are unavailable. Plants can't find animal manure or worm tunnels, so you'll have to provide things yourself * Rivers, streams, and underground water sources are missing entirely. there's no pool to tap into when the weather gets dry. * Plants sometimes share nutrients through a fungal network. This is not an option for your potted plant * Unless your plant is native to the area, many of the species it has a symbiotic relationship with will simply be missing. If a plant is typically protected from aphids by ladybugs, but ladybugs aren't found in your area, there might not be a species that will see the plant as fertile hunting grounds, leaving your plant unprotected. * Your plant does not have the room to stretch out that it normally would. A wild plant will have roots that cover a vast area, allowing it to gather what it needs from where what it needs is. your potted plant only has a pot to search.",
"Survivorship bias is also a factor. You're only seeing the ones that survived, not the many that didn't make it.",
"Darwin… plants evolve to adapt to their environment. Potted plants did not evolve to their environment. If you want to have perfect potted plants, you need to mimic the plants’ natural environment. The closer you get (temperature, sunlight, soil nutrition, water, noise, latitude, mycology etc.) the more robust your plants will be.",
"I guess I've always thought that for every 1000 wild seeds out there, one actually makes it. Its why allergies suck.",
"What others have said about the benefits of a functional ecosystem are true, but it's also a case of survivor bias. Think about how many seeds any given plant casts out each year, and how many actually thrive. What you're seeing are the few success stories, not the thousands and thousands of failures.",
"> potted plants need costant attention Is not necessarily true, at all. There are many plants you can basically ignore for a month at a time without consequence",
"Why do you think some trees drop hundreds to thousands of seeds at a time of seeds at a time… they wont all survive. But year the ground is more self regulated, in their natural environment they evolved to live in compared to a pot. Also more room to spread roots etc. Pests do kill some, but the hardier trees make it, and them make slightly hardier trees a few decades later. In theory",
"The ground is a never ending and ever replenishing store of nutrients and water. More importantly, those plants and forests you see are the result of thousands if not millions of years of natural selection and that means only the best, toughest, most vigorous, most resistant to pests and diseases native to that area, etc end up making it. After a while each strata of a forest is occupied by the group of plants that survived this natural selection process. There’s a whole lot more to it but it’s what it is in a nutshell.",
"Each system of the tree gains benefits for being outside versus being inside. Roots: Trees outdoor have a constant source of nutrients as long as their roots grow just a little bit further. Plants indoors will deplete their nutrients in 3 months and then start to become rootbound. Rootbound can cause a plethora of problems for the plant that outdoor plants do not struggle with. Cambium layer: plants and tree outdoor send nutrients up the cambium layer to grow softwood ok the inside and bark on the outside of the tree. That cambium layer is constantly provided with nutrients to make the tree grow vigorously. Trunk / stem: The outdoor plant is constantly at the mercy of harsh winds. Wind causes a plant to grow shorter and strong stems to support the plant. Consequently the cambium layer is more efficient. Leaves: an outdoor plant has increased efficiencies of photosynthesis because their is a higher rate of carbon monoxide outdoors than indoors. Indoor plants receive none of these benefits and more that I didn't mention."
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o3s2i6 | If all noise cancelling headphones do is reverse the soundwaves coming into them in order to ‘cancel’ the background noise, why can’t they cancel a sine wave completely? | Technology | explainlikeimfive | {
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"They can. But only at very specific spots and, since your ears capture sound over an area, they can't completely make you not hear it. If you have a pure sine wave signal (a pure tone) and broadcast the exact opposite, you will indeed cancel to exactly zero wherever the loudness (amplitude) and alignement (phase) of the reversed wave exactly opposes the incoming wave. Assuming that the cancelling signal is louder than the incoming signal, this will always happen \\*somewhere\\*. But it'll be a very small region. Your eardrum is a whole area so you can't cancel the incoming signal across your whole ear, so some will get through, so you'll always hear some of it. Edit:typo",
"In addition to the great explanations already shared, when you hear a sine wave you’re hearing the wave, plus all the slight echos from the environment. Your brain does a remarkable job cleaning it all up for you, while using those echoes and the folds of your ears to interpret the direction the sound might be coming from. (As an aside, consider this: with both ears you can imagine how your brain could figure out where something is on the horizontal axis, based on comparing the left and right input. But your brain is also able to guess approximately where on the vertical axis a sound is coming from. With your eyes closed, if there is a click straight ahead of you, you can tell if it’s up high or down low.) So, what hits your eardrum is never a simple sine wave. The simple sine wave can be canceled but you still hear all the slight echoes.",
"Because there is always some small distance between where the outside sound is sensed by some sort of microphone and where it needs to be cancelled, ie at the entrance to your ear canal. That introduces a small time discrepancy. The effect of that varies with frequency of the sound in relation to the length if time for one cycle of the sine wave.",
"Because they're using miniaturized components manufactured to a specific cost and not lab-grade equipment in a tightly controlled environment. What they can do is pretty amazing but all of the variables they cannot control makes the situation difficult. Noise bleed via physical transmission(making the headphones vibrate or noise passing through the headphones), air leaks between your ears and the headphones, physical conduction of sound (feeling the sound due to the pressure waves). They're also extremely limited in amplification and to offset a sound you have to produce the opposite off that wave in frequency(pitch) as well as amplitude(volume). If it's not the same amplitude, you'll simply get an attenuation (lower volume)",
"To completely cancel the sound the reversal would have to be instantaneous, but there is a finite but non-zero lag between the sound being picked up on a microphone and when it goes through the circuits reversed."
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o3t75r | Why we do hate alcohol at first but slowly come to like it? | Biology | explainlikeimfive | {
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"What your describing is a pretty subjective experience. Some people like the taste of alcohol right away and some people never like it. The truth is, alcohol itself doesn't have much flavor, it just provides a feeling of astringency on our tongues and a burning sensation in the backs of our throats. That is just a shock when you don't expect it but can become enjoyable with time. For ELI5, you get used to it over time and it tastes better when you know to expect it",
"I quit a few years ago at 44yo not through denial. Social conditioning is all it is. I can remember using cider as a step to beer as a new legal drinker. Alcohol in its pure form is toxic and will kill you. We have to add sugar and other flavours to make it slightly palatable. We learn to like the intoxication get addicted to it.",
"Because you're literally poisoning yourself, and your body recognises this and reacts accordingly. Eventually, if you continue to consume alcohol, your body will adapt to it. The animal part of your brain essentially just assumes that this poison is being forced on you, so it will lower it's alarm signals and try to manage it as best it can. Those warning signs start to go away. It also starts to associate the percieved benefits of being drunk with the drinking of alcohol, and a feedback loop is created."
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o3te79 | What does "e" represent in math in the most simplest terms? | Like I've seen posts about this, but none of them seem like they know what they're talking about? What does e represent? | Mathematics | explainlikeimfive | {
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"So pi is a special number in maths. It's defined as the ratio of the circumference (edge) of a circle by the diameter (length across the middle). This is a nice tangible definition, but pi crops up in loads of places. Really, this is because there are a lot of places where circles are hiding in the background, and pi is like the key number of circles. Euler's constant, e, is a bit like this. It crops up in loads of places. These areas might seem to be unrelated, but there's something linking them all together. The difficulty is that where e comes from isn't as simple as a nice shape. e is to do with change. How quickly things change, and how this rate of change changes. There isn't something as tangible as a circle. But it crops up enough that we notice it, and so we give it a special name. The number is roughly 2.72. If you plot a graph of y=e^x and then you measure the slope at any point along the x axis, you'll find the slope is exactly e^x . This is the only number that does this. It's sort of the key feature of e. When mathematicians try to work out the slope of a line, we use something called differentiation. There are a bunch of rules you can use to do this, but e^x is the simplest, because of what I said above. It's its own slope. So, if we can find a way to sneakily change a function to have an e^x in it, we can make our lives a whole lot easier. Edit: thanks :) Edit 2: double thanks :)",
"Let's say you go to a bank that offers 100% interest per year. You deposit $100. After a year, you check your balance, and you get $200. But then you see an offer at another bank. 100% interest, compounded every 6 months. So 50% interest at 6 months, another 50% on the new balance at the 1 year mark. You get $50 and then $75 for a total of $125 in interest, or $225 total. Not to be outdone, the first bank offers you monthly compounding. (100/12)% per month. After the end of the year, you end up with $261. The second bank goes back and offers you compounding weekly. 52 compounding periods of (100/52)%. You end up with $269 after the year. That's more, but not as big of a jump as before. The first bank tries to get you back, they offer daily compounding. 100/365% interest every day. You end up with $271. Not to be outdone, the second bank offers you per-minute interest. 525,600 compounding periods. After a year, you get... $271. The pennies might have changed, but nothing more is really happening. We've reached the limit. That's where it stalls out. You can generalize the formula we were using to be (1+1/n)^(n). As *n* got bigger, we got more compounding periods, but for a smaller amount. As *n* gets bigger, the equation approaches *e*. This is the natural growth of the exponential function. *e* shows up everywhere in basically everything dealing with exponential functions. This is especially true because every single exponential function can easily be changed to work in form of e^(x) (more accurately, y=b^x = e^(ln b * x)).",
"People have explained what e is, so here's a couple places where e shows up in math. * You're a trader using a camel to transport hay bales. If the camel tries to carry more than 1 kg of hay, its back will break. You load up hay bales onto its back one by one, and each hay bale has a random weight between 0 and 1 kg. On average, how many bales will it take to break the camel's back? * The answer is e. * On a game show, you are presented with n boxes of cash. The boxes have different amounts of cash. The rules are: You can open them one by one in any order you'd like. Once you open a box, you must then choose whether to take the box of cash or not. Once you open another box, you can no longer choose any previously opened box. In the case that you have opened all the boxes, you will need to pick the last one you opened. You can only pick one box to go home with. What is the optimal strategy to win as much money as possible? * The answer is to first open n/e boxes, reject them all, and then choose the first box which contains more cash than any of the first n/e boxes you opened. * n people are playing Secret Santa. They choose who will send a gift to who by putting all their names in a hat, then having each person pick one out randomly. What is the probability that nobody will choose themselves? * It turns out that as n gets larger and larger, that probability approaches 1/e.",
"Other answers here are great, but I want to give a completely different answer just in case it’s relevant. If you ever see a number written like 6.02e23, that is *not* the transcendental number e=2.71... but a way to denote very large numbers called “engineering notation “. It’s equivalent to 6.02 x 10^23 , and means you should shift the decimal place on the first number over by the number of places given by the second. That is, 602000000000000000000000. Since many people see this system in computer programs that deal with large numbers, I thought I’d mention it because the other answers will be really confusing if this is the context which prompted the question.",
"E has tons of different uses it I think the simplest is compount interest. Imagine you had 1€ and got 100% interest per year. How much would you have after one year? Well 2€ that's easy. Now imagine that the interest wouldn't be payed out once a year but twice (you only get half the interest of course because only half a year has passed). How much would you have after a year? You'd get 0.5€ after six months giving you 1.5€ and and 0.75€ after the next six month so you would have 2.25 €. Thazs better! How much would you have if the interest wouldn't be payed out twice a year but continuously? Correvt you'd have e€",
"e is euler’s number 2.7182818… its digits never end, just like pi. A function y = e^x has a slope of (slope y over x) = e^x. This means it’s as important to slopes of functions (the basis of calculus) as 0 is to addition and 1 is to multiplication. And it can be further found that e, despite describing exponential growth, can also describe trigonometric functions like sin and cos via the use of imaginary numbers. Linking exponential growth (which is a very basal characteristic of our universe- quite often the more of something you have, the faster it grows, decays etc) to cycles and periodic events (anything from sound vibrations to car dampers to the brightness of stars) like this is extremely powerful and is the basis of many applications of math, physics, engineering, you name it. For example, the Fourier transform uses e^i and can tell you, from some data over time, the frequencies of events creating that data. In short, it’s important because it is the identity of exponential growth, but has many many uses beyond that.",
"Well, it's a number. An irrational constant, like pi. It's about 2.718. It's useful wherever you do exponents",
"One element I haven't seen mentioned is that e tends to imply infinite feedback of some sort. That is, when you see a result that includes e, there is almost certainly some underlying process whose output is fed back into the input and you're looking at the steady state of a potentially infinite process.",
"e is \"euler's number\" or \"the natural number.\" It is a mathematical constant similar to pi that represents 1/1+1/1\\*2+1/1\\*2\\*3+1/1\\*2\\*3\\*4... Do you have additional questions. Edit: If you are wondering \"yeah but so what, what was euler's number invented?\" The answer is so that you can make a sin,cos,tan fucntion on a calculator. You may be surprised by this but sin is simply a formula using eulers number that is sin(theta)= (1/(2j))\\*(e\\^(j\\*theta) - e\\^(-j\\*theta). So basically eulers number was made to save us all some time, and sin theta was also made to further save us time."
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o3tih4 | If the interstellar medium (ISM) is defined as regions of Space beyond a Star’s influence, why is there an ISM between the heliopause and the Oort Cloud? | Other | explainlikeimfive | {
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"The heliopause is basically the limit of the Sun's physical influence...it's the outer edge of the Sun's particle bubble. Since what's beyond that, by definition, can't be from the sun then the contents must be interstellar medium. The Oort cloud goes \\*way\\* farther out than the heliopause. You might be thinking of the sun's gravity...that doesn't have a limit to it's influence, it just gets so weak that nobody cares if you go far away...but that's much much farther than either the heliopause or the Oort cloud. And the gravity well doesn't have anything to do with the heliopause."
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o3u8e2 | Why do mockingbirds sing the songs of other bird? | Biology | explainlikeimfive | {
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"This is where they got their name. Scientists believe that mockingbirds imitate the calls and songs of other birds to discourage these birds from settling in the mockingbirds' territory by making it appear heavily populated.",
"If i remember correctly mocking birds imitate other birds to make it appear as if the area is already populated by many other species so other birds dont try to move into the mocking birds territory"
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o3ude6 | What actually happens internally when we "see stars"? | Biology | explainlikeimfive | {
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"Your retina becomes starved for oxygen, for one reason or another. This makes all the rods and cones that are not at that very instant right next to a fresh red blood cell dim significantly, since they don't have enough oxygen to do their job (converting light into sensory information and sending it on to your brain). The ones that ARE right next to a red blood cell aren't dimmed nearly as much, so the light that hits them appears brighter. As those blood cells flow through the blood vessels in your retina, the bright spots appear to 'swim' through the air in predictable patterns, following the path of blood flow."
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o3uobd | why does infrared heats things faster than more energetic light waves? | More energy in means a higher final temperature, how does this work? | Physics | explainlikeimfive | {
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"Well, it depends on absorbtion. That's why microwaves heat water so well. Visible light is reflected off things that you shine it on."
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o3w29c | why does wood when its burning sometimes 'pop' with little sparks? | I'm not exactly sure why it does that. Is there something in the wood? | Biology | explainlikeimfive | {
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"It usually occurs because there is a pocket of either water or sap in the wood. This pocket becomes superheated and the pressure builds until it releases explosively (the “pop” you hear). The sparks are little bits of wood that are burning that get knocked off when the pressure releases.",
"It happens when wood isn't fully seasoned. There are pocket of moisture still in the wood and the heat creates steam pressure which expands until the moisture pockets burst creating the popping sound."
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o3wde5 | Why is water cloudy from the tap, then turns clear afterwards? | Other | explainlikeimfive | {
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"Most sinks in the US have aerator caps screwed into the faucet spout. It looks like a fine mesh screen. What you're seeing is water being forced through it which makes it seem opaque since the water stream is now mixed temporarily with air, but once the water settles it is clear. The main purpose of an aerator is to reduce water splashback. In some cases it can be used to modify the water pressure and even slightly filter debris or gunk in the waterline. You could go to your sink right now and remove the aerator, and then your water should come out more clear."
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o3wfk3 | What is wind? Where does it come from? And is there always wind in a very high altitude? | Physics | explainlikeimfive | {
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"BLUF: Wind happens due to unequal heating of the earth’s surface. There is always wind at high altitudes up to a certain point. That point is the tropopause (aka the top of the troposphere) There are 3 main cells that controls global weather. Those are the Polar, Ferrell, and Hadley cells. Within the Hadley cell, closest to the equator, is a system called the Tradewinds. Those winds carry into the Ferrell cell and then into the Polar cell. I’ve been a meteorologist in the USAF for about 4 years now, but its been just as long since I’ve learned the material so my answer may be a little off."
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o3widf | Why does vinegar preserve things ? | Chemistry | explainlikeimfive | {
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"Two big reasons. First, the acidity makes it difficult for bacteria, mold, and oxygen to turn the food its trying to preserve. The second is that vinegar is a desiccant, so it draws water out of things which further inhibits bacterial and fungal growth"
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o3wxw6 | How are ants so strong? | So we've all heard that ants can carry upto ten times their weight. Which so much more than what humans can do. A 150lbs person lifting 1500lbs even as a deadlift is an inhuman feat. I read some online articles about it but I don't think I have clarity on it. Can someone explain it to me like I'm 5? Thank you in advance. Edit: not sure if the flair should be biology or physics lol | Biology | explainlikeimfive | {
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"In addition to the cubic mass issue that's been brought up already; it's a matter of leverage in the form of torque. It depends on where the moment arm (the distance as a percentage from the point of rotation) is in the lever (joints are levers.) Our jaws, for example, are the strongest joints in our bodies per muscle weight because they have a nearly direct pull on whatever the muscle is working on. The masseter muscle spans far from a low degree angle joint on both sides of the joint, so it has a ton of pulling power. Monkeys are about 9x stronger than humans in a lot of their joints pound per pound because their moment arms are about 9x further up their joints. This allows for some awesome tree swinging! Even a small monkey can easily dislocate the arms of a human. However, when you increase the moment arm you sacrifice speed! Humans are therefore 9x faster across the joint as monkeys too, so we can run and throw balls hella fast compared to monkeys. So, ants are like monkeys, they're simply set up for more leverage across those specific joints.",
"This is actually more of a physics question, but also sort of biology, so you were kinda right. So first I need to explain something called the Square Cube Law. Imagine you have a cube that is 1 foot in every direction and that weighs one pound. If you double the dimensions of the cube, it is now 2 feet in every direction, but weighs 8 pounds. 3 feet in every direction brings it to 27 pounds, and so on. Even though the dimensions are increasing at a steady pace, the mass is increasing exponentially. Now, what does this have to do with ants? Everything. If you compare the physical amount of weight ants can carry to humans, humans can obviously carry much more. But *proportionally*, ants are stronger as they can carry more weight relative to their size. Smaller animals have a smaller mass:body weight ratio, and thus are able to carry more relative to their size. We also see this in the opposite direction; while elephants seem quite strong (they can carry several hundred pounds), they can actually only carry ~10% of their body weight. This would be equivalent to an adult male only being able to carry 15-20 pounds at any given time, ever. Tl;dr smaller animals are proportionally stronger because of the Square Cube Law, and larger animals are proportionally weaker for the same reason"
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o3xbx2 | If everyone likes diffrent stuff, than how can people like Gordon Ramsey say that something is "absolutely disgusting" as a fact? Wouldn't it just be the opinion of one guy? | Other | explainlikeimfive | {
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"Most people like similar things. It’s really that simple. Were you looking for a technical mind blowing answer?",
"Some people are considered an authority in their field. So everyone can like different cheeses but the cheese makers still want to impress the judges at the cheese championships because the are considered the authorities of cheese and their opinion is considered more important than others. It still doesn't mean they're right."
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o3xehl | what is the difference(s)? between SNRI’s and SSRI’s? | in the middle of a long mental health battle and have been switched back and fourth on many prescriptions through the years, google only uses words like “reuptake” and “inhibitors” without explaining what those words mean in a medical context. it’s complicated and i really find examples help my understanding of things. analogy’s are also welcome. thanks for any reply’s! | Other | explainlikeimfive | {
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"I know others have already answered, but I like this topic so what the heck. Serotonin and norepinephrine are two kinds neurotransmitters. When a nerve needs to send a message to another cell, it does so by releasing a bunch of neurotransmitter chemicals in the space between the two cells. They touch receptors on the other cell, and when enough receptors are activated, something will happen in the receiving cell. After sending the message, they sending cell has to reabsorb (or, reuptake) those same neurotransmitters so they can be reused. SSRIs affect serotonin, and SNRIs affect serotonin and norepinephine. They slow down the process of reabsorbing the transmitters (as in, they Inhibit the Reuptake), which means the neurotransmitters stay out there between the two cells for longer. This means that the signal is more likely to be received on the other end. What we don't really know is why that helps some people manage their depression.",
"SSRIs are selective serotonin reuptake inhibitors (Prozac, Lexapro etc) and SNRIs (Cymbalta, Pristiq) are selective norepinephrine reuptake inhibitors. Serotonin and norepinephrine are both important mood regulators with various functions in the body. Serotonin and norepinephrine are neurotransmitters, which means they're chemicals which brain cells use to communicate with each other. Think of both as messengers which are used to send different kinds of messages. SSRIs and SNRIs work by increasing the activity of serotonin or norepinephrine in the brain, which increases the activity of brain cells that use these neurotransmitters to communicate. Both types of drug do this by preventing brain cells from re-absorbing serotonin or norepinephrine, so that they stay in between the neurons and keep doing their thing instead of getting broken down and reused. Treating depression/anxiety is complicated because mood and well-being rely on a ton of interconnected systems and chemicals that all do multiple things. You can't just increase serotonin levels and feel happier, it takes time for the change in brain chemical activity to be felt throughout all the systems that regulate your mood. We don't really understand all of the reasons these drugs work or don't work in different people. Best of luck with everything and lmk if you have questions, I'm not great at explaining things haha",
"Imagine you’re playing hungry hungry hippos. Over time, the little beads or whatever get eaten up, right? Taking an SSRI is like reducing the number of players so the beads last longer. Basically, serotonin needs to flow to a lot of different places to be affective. Reuptake is when the serotonin is reclaimed and it can’t be used anymore. By making the receptors (ie, the things which reclaim the serotonin) less effective, we can guarantee that the Sheraton in lasts longer and reaches the places it needs to go! Unfortunately, I can’t offer an explanation for the other.",
"SSRI’s inhibit (stop) the reuptake (absorption/your brain absorbs/eats the excess) of serotonin In your brain so that more is available to use. SNRI’s inhibit the reuptake of serotonin and norepinephrine in your brain so both of those are available to be used. This article explains how they work pretty well URL_0"
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o3xqn1 | targeted marketing | Have you ever been talking to someone about a specific product or food and then the next day, someone else is starting to see advertising on their phones for that very thing? I was recently talking to my husband about a German sausage shop called the Sausage Man for a BBQ and then the next day, my brother-in-law started seeing ads even though he wasn’t even in the conversation but sat in the same room. How does that work? | Technology | explainlikeimfive | {
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"Sometimes it is coincidence! But technically, the apps on the devices will have pre-configured rules which will use phrases heard in this case to target advertisements or offers or rewards for you. This is a very high level explanation. In reality, it is complicated, businesses configure weighting for lots of different attributes and other factors to be able to give you the most useful and applicable advertisement or offer in front of you. YouTube, I am sure will be doing the same for their recommendations. So it's the phrases that matter, not the entire conversation. So for example, if the rules are configured for \"UFOs\" then even if you said something about sausages for a long time but uttered the word UFO maybe a couple of times, it might be sufficient to trigger those recommendations. It's not super easy to configure very effective rules, that's why they add machine learning behind it, which will come up with the correct weighting based on statistics rather than a hunch.",
"On the one hand it's confirmation bias. If you're talking about a product then you're primed to view it. So you're just noticing a relevant ad. On the other hand, if you actually search for the same product or navigate to a page that sells that product then advertisements learn your preference for a product. \"The Algorithm\" (TA) goes a step further, and begins predicting other products that are similar to the one you searched for. Let's say you search baby diapers, so TA will guess you probably will need formula, wipes, baby powder, and other relevant baby products. So it seems like advertisements are being targeted to you. TA goes yet another step further by identifying your browsing profile as a whole and comparing it to other profiles. So you don't even have to be planning a child, but if you share enough trends with other people that are planning a child, you might get a few ads regarding diapers even if you don't have a kid. In this case the advertisement failed, but this logic is applied across your entire profile. On the third hand, there are some apps that do passively report audio and feed you ads that are relevant to the recordings. I remember Facebook and Facebook Messenger caught a lot of flak for this a few years back. I'm sure more apps or smartphones may be doing the same thing and have it hidden somewhere in their Terms of Service. When you take all three of these together in tandem, TA can almost appear clairvoyant in how it selects advertisements.",
"A lot of that is just coincidence. We see so many ads that most of them fly by without us consciously registering them. Your brother-in-law could have seen the ad before, but didn’t pay attention until your conversation. (This is especially likely if the shop is in your area, since many ads are targeted by location)."
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o3yiuf | - How did the mafia make money off labor unions? | Other | explainlikeimfive | {
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"It depending on your position in the mafia hierarchy. Lower level people would be given \"no show\" or \"no work\" union jobs. Those were jobs where an employer hired them but they either didn't show up or showed up but didn't work. So, for example, you're a shipping company that needs to hire 20 teamsters to drive your trucks. The Teamsters Union makes you hire 25 people. 5 of those people are low level mafia enforcers who just don't show up to work but get paid as though they do. Any one person might have several of those plus a no work job - and those were all well paying, middle class jobs. For the higher level mobsters, most were just given a cut of the union dues, which were quite high. They would also get a cut of the salaries paid to their underlings who were working the no show/no work jobs. For the mafia more globally, unions had huge pension funds. Those funds would provide no-interest, no-recourse loans to legitimate mafia backed projects. A good example of this is Las Vegas, which was built almost entirely with no-interest, no-recourse loans that were made to investment companies affiliated with the big mafia families. What a \"no-recourse\" loan means is that if the project fails, the lender is limited to going after the assets of the failed business. No recourse loans are basically unheard of in large projects because when a large project fails its assets typically become worthless. Institutions that make large investments typically require the partners in the project to put up a substantial percentage of their own, personal wealth as collateral for the deal. Being given a no-recourse loan is like being allowed to gamble with someone else's money. If you get a $50 million loan from the Teamsters Union, you've basically just been given $50 million to gamble in a real estate investment. If the investment fails the Teamsters lose everything while you lose nothing. If it succeeds you could make hundreds of millions of dollars and the Teamsters only get their $50 million back despite having taken all of the risk.",
"The unions would have employees.....those employees would be paid salaries. Those salaries would go to senior members of the mob and give their families all the benefits of full time legitimate work.....while doing crime things.",
"In the late 70s I was a member of Amalgamated Meatcutters and Butcher Workmen local #1 out of Utica NY. I was a grocery checker. This local was what was known as a \"sweetheart union.\" We made minimum wage, and had to pay union dues. We could not get a copy of the union contract even to look at. It was not posted anywhere. The union dues went to the mobsters. The store gave kickbacks to the mobsters. There were suspicious shipments on and off the loading dock. There was something about narcotics moving on produce trucks, idk details. Bonus fact: the manager of the store was named Al Soprano 😂",
"A few ways, but the essential factor is that they were union members that received money and benefits. Other factors: 1. biggest leverage potential was in monopolizing so that prices could be driven up. Mafia did this with vending machines, unions, drugs. Creating barriers to entry so that they could prevent competition from underselling them...while finding ways to avoid taxation and costs was essential to making mafia advantageous over putting the same energy into legitimate options. 2. Union contract renewal. Traditionally \"strike breakers\" such as Pinkertons were hired to encourage people to go back to work and thus the power of the strike was broken. When the mafia offered to protect the \"strikers\" in exchange for % of the sign on bonuses of fake people that don't exist...and subsequently collecting wages from the nonexistent people helped. This is covered pretty well in The Sopranos where the mafia get involved with lots of white collar things to collect a wage by showing up for work whenever there is a labor audit."
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o3z1gy | What makes blue-light so bad for our eyes? | Biology | explainlikeimfive | {
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o3z97g | If every part of the universe has aged differently owing to time running differently for each part, why do we say the universe is 13.8 billion years old? | For some parts relative to us, only a billion years would have passed, for others maybe 20? | Physics | explainlikeimfive | {
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"We're simply judging by earth years not relativistic years. Sure technically, certain parts have advanced further in \"time\" due to the effect of gravity. But according to us here on earth, looking out. There has been approximately 13.8 billion years since the big bang. (A year being the time it takes for the earth to complete 1 full cycle around the sun)",
"Physicist here. Here's a copy/paste from [my answer to an old /r/askscience thread on the topic that included lots of good discussion.]( URL_2 ) ---- It depends on how we measure it, but all reasonable reference frames give about the same value. The most precise measurements are based on the [Cosmic Microwave Background (CMB)]( URL_1 ). There is a convenient reference frame called the [comoving frame]( URL_0 ), in which the CMB light coming from all directions is equally redshifted. This is also the reference frame in which the universe is the oldest, and is the reference frame we use when doing most cosmology. Our solar system is moving at about 371 km/s relative to the comoving frame, which gives a time dilation factor of only 1.0000008, which is why it doesn't matter much what (reasonable) reference frame we pick. In this frame the universe is only about 10,000 years younger, out of 13.8 billion years.",
"The oldest anything in the universe could be is 13.8 billion years old. This would be a hypothetical object that came into existence at the big bang and has been stationary (called comoving) relative to the cosmic microwave background for its entire existence. You are correct that there is no universal time for the whole universe, and any reference frame is valid, but using the CMB makes the most sense since it's the leftover radiation from the big bang. It's also important to note that most parts of the universe are pretty close to being comoving with the CMB, so most of the universe is pretty close to this age. The only places where you'd expect a large difference in the measure of elapsed time would be close to massive objects like black holes and things that have been moving at relativistic speeds for most of the existence of the universe.",
"I'm no expert but as I understand it everything comes down to frame of reference. We are trying to measure the age of our part of the universe. The assumption is that physics works the same in every part of the universe so if we could instantly teleport to the farthest place we can see and take a measurement there we would get the same answer. Of course time dilation, univers expansion and the like produced some interesting effects like Methuselah star: URL_1 And we're not even so sure about the 13.8 billion years old part: URL_0",
"For 99.9% of the conversation, the only perspective that everyone understands is that of humans living on earth. So it makes sense to use that perspective as a measurement point. It would not make a whole lot of sense to say it is xx \"years\" old from the perspective of someone living on another planet since pretty much no one understands anything from that perspective. We can say that a \"year\" on Jupiter is about 12 of earth years. Would it make much sense to say that someone is 2 Jupiter years old? It is perfectly definable and measurable, but such a measure is pretty meaningless to everyone. Science is about discovery and the communication of discovery. So, where possible, it is logical to choose a way of communication that is relatable to most people.",
"There are several good answers here, but I think it's worth mentioning how rare relativistic things are. Most things in space tend to be moving at about 0.1% the speed of light. Now that seems fast, but it turns out the relativistic effects that make clocks move differently are very small until you hit about 90% the speed of light. You can also change the clock's speed with heavy gravity, but again you need to be near a black hole for that to matter. Overall, you get that for pretty much all the clocks out there, the age of the universe is going to be the same, give or take a few thousand years. Last thing worth noting is the cosmic microwave background. Basically there was a time the universe was full of gas that was so hot we can still see the glow from it today. You can tell from this glow whether you are moving with respect to that gas, so you can use it as a reference point for a standard speed, and so a standard clock, for the universe. As I describe above, it doesn't make much difference to account for this, but it's pretty cool.",
"No no, he's got a point, it's not even a \"we are humans so we describe it in a way humans understand\" I get the whole \"from our point of view, the universe is x age\" but what do we gain from saying? Like, if we find a rock, and we know this rock has existed since the start of the universe, we cant say that its 13.8 billion years old because we dont know the speed at which its travelled for the last 13.8 billion of our years, it could be older if it travelled slower than us, or younger if it travelled faster, and thats ignoring the effect of gravity",
"I'm not smart enough to offer an answer, but this video on the [Twin Paradox]( URL_0 ) might offer some additional insights.",
"Time can run differently for other observers, yes. However, this difference is with respect to earth time. The different observer wouldn't measure the age of the universe in earth time (and get a different result) but would instead measure it in his own time and get 13.8 billion as well",
"Don’t think of time as something measurable in and of itself. What we experience as time is the effects of entropy. Entropy is how things change (super simplified version) and time is how much things change. In places where time doesn’t move as quickly, entropy sort of slows down. For example, if you have a nail that is rusting, it will rust more slowly in places with higher gravity or speed than others. If you have two rusting nails and one of them is near you and the other is 1000 lightyears away, it makes no sense to say “The entire universe is x amount of rust on my nail.” and expect all of the nails in the universe have rusted the same amount. All of the nails have been rusting at different rates. Instead, you would have to say, “My nail rusts at this rate, my nail has rusted this much, therefore the local ‘time’ is x.” You would then say that the universe is x years old compared to your nail.",
"Where in the world did you get this idea from?",
"A guy by the name of hubble figured out that some of the smudges in the nights sky were actually other galaxies and not just nebulea. In figuring this out he also discovered that the ones which were further away from us were also moving away from us the fastest. Through plotting these galaxies on a graph of distance and speed he determined the rate of expansion called hubble's constant. Through a little mathematics (1/hubbles constant) we can determine how long the universe has been expanding for, approximately 14.4 billion years.",
"Cosmologist here. You are right! Every point in the universe has aged differently. I’ll give two levels of explanation: Easy: 13.8 by is actually the average over all the different points Hard: Have you ever heard of the expansion of the universe? Everything is moving away from everything else due to the expansion of space itself. This is called the Hubble Flow. If you don’t move but just go with the flow , ie only see the distances of galaxies change because space is expanding and not because you are moving in it, you are said to be a comoving observer. So 13.8 by is the time as measured from someone who has been moving with the hubble flow since the big bang.",
"First of all, ask yourself the question: why is the universe so dark? If the universe is infinite and contains an infinite number of stars, shouldn't it be brighter? A lot of smart people asked this question too and it's know as [Olber's paradox]( URL_2 ). Next, convince yourself that the further you look in the universe, the further you look in time. If you don't understand this, let me try to explain it with a simple analog. Suppose you are giving a small party. One of your friends lives 2km away and the another one 15km. they both travel by bike, because they care about the environment, with a constant velocity of 20km/h and arrive at the same time at your place. which one of them has left his house the earliest? The same reasoning can be done for a [photon]( URL_0 ) (fancy name for light particles, \"why is light a particle?\", that's a whole other story). A photon that comes from a distant star will have traveled a lot longer than a photon from the sun and thus has to leave the star at an earlier time than the photon from the sun. Now back to Olber's paradox. The paradox can be solved by stating that the universe has a finite age (13.8 billion year). This means that we can only see photons that have traveled less than 13.8 billion years. Or in other words, and this is the clue, we can only see photons from stars that are less than 13.8 billion light years away (a light year is the distance a photon can travel in one year). Remember: the further you look in the universe the further you look in time. We don't see every star in the universe and thus the universe is a lot darker (less stars == > less light). Saying that the universe is 13.8 billion years, is thus a way the explain why the universe is so dark. I now, it's a lot to read, but I need to explain just one more thing before I can answer your question, so bear with me ;) The universe is not completely dark. If we look at a dark spot on the hemisphere, we can still detect some radiation. This is known as the [cosmic microwave background]( URL_4 ). Smart people have stated that this is the light from the [Big Bang]( URL_3 ) (the beginning of the universe) that has \"dimmed\" over time. This background light is almost the same at every place in the universe. Aha! so now we can understand why we say the universe is 13.8 billion years old. The finite age of the universe depends on how dark the universe is and because the universe is equally dark at every point, we can find that the universe is 13.8 billion years old no matter where we look. I know that this isn't a direct answer to your question, but in order to give you that, I think that we need to talk about special relativity, redshift, [Hubble's law]( URL_1 ), ... Stuff that makes your head spin, or at least mine, and I don't think I can do that in a reddit comment. Just keep in mind that a lot of smart people are looking at stars and that they figured out how to account for a lot of stuff that can change a picture of the night sky, like relative motion, and after all those calculations, they find the same cosmic microwave background. Quick note: I put some links to wikipedia in this explanation to be complete, but be aware that it can melt your brain. Sorry for the long post, hopefully someone can explain it in less words ;)"
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o3zdvn | How can you multiply something by a rate? | Specifically, e = mc2. How do you get one unit of measure (joules) by multiplying it with a different unit of measure (grams) by a rate (speed of light which is m/s)? | Physics | explainlikeimfive | {
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"This is because joule (and J) is just a more easy name (abbreviation) for (kg*m²)/s² which one joule is defined by. So basically you can imagine calculating with the units of measure, just like m*m=m². But because always writing (kg*m²)/s² is kind of annoying we call it Joule. So J is just an abbreviation for (kg*m²)/s² and it is like that for all other instances where this happens aswell.",
"That’s just how the units work. Energy is measured in joules, and joules can be written in a more complicated Way as kg*(m^2/s^2). This holds true for other ways of getting joules, say for Kinetic energy, KE = (1/2) m v^2 (1/2) kg * (m^2/s^2) Or Potential energy PE = mgh kg * (m/s^2) * m = kg * (m^2/s^2) You’re multiplying by a rate, sure, but you’re getting a totally different unit of measurement.",
"The entire point of e=mc^2 is that mass and energy are interchangeable. The units of measurement are somewhat arbitrary, but you can get from kilograms to joules because according to e=mc^2, mass and energy are the same thing in different forms! Remember that joules can be presented as newtons per meter (energy equals a force over a distance over some time). What is a newton then? It's a force that represents accelerating one kilogram over one meter over one second squared. Do you see now how mass (kilograms) can ultimately relate to energy? In the case of e=mc^2, the mass is considered to be in a rest frame (no velocity or momentum). Since all energy is transmitted at the speed of light, we can find out how much energy is in an object by multiplying the mass times the speed of light squared. When mass is converted to energy, that energy is moving at the speed of light by definition. You might ask, why is the c squared? We know from the formula for kinetic energy (ke = 1/2mv^2) that the kinetic energy of an object increases exponentially with the velocity of that object. Therefore, the latent energy in some mass isnt just mass times c, but rather mass*c^2, because energy scales exponentially against velocity. ELI5: joules can equal kilograms times meters/second^2 because energy is interchangeable with mass.",
"A joule is defined as the energy required to exert a force of 1 Newton (1 m/s^2 ) on a mass of 1 kg over a distance of 1 meter. Therefore a joule is equal to 1 kg × 1 m^2 / 1 s^2 . From e = mc^2 : *m* gets you the kg, *c^2* gets you the (m/s)^2. Presto bango, that's all you need to calculate Joules.",
"I think understanding “Derived” and “Base” units might help you. In Physics there are 7 base units, these are the simplest ways things interact (s is time in seconds, or kg is mass for example) Now lets get into a “Derived” unit. If we take the unit of force “Newtons” and break it open, its actually just base units (Mass, Distance and Time). This allows us to compare, multiply etc with different physical properties and even reduce them to these if needed.",
"Just working with units is a very powerful concept in physics. The kinetic energy of a moving object is given by a similar formula; 0.5 x m x v^2. And the gravitationalpotential energy: m x g x h g being an an acceleration (meters per second per second), and h being in metres - you get the same unit combination. You can almost imagine that Einstein observed that mc^2 represented an amount of energy - an enormous amount of energy - and decided to work out the possible meaning of that."
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o3zpps | When an body part gets swollen. Where does the fluid/volume come from? | Biology | explainlikeimfive | {
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o400vn | How does gpu and cpu work by comparing them to a different object to explain their similar functions | What I mean is that if you can think of an object to compare them to and explain their function so it will be easier for me to understand. Like comparing a chest's size to a phone's storage and how much a washing machine can wash clothes comparing to RAM. Despite learning about CPU's and GPU's description, I still can't understand how they work specifically | Technology | explainlikeimfive | {
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"A cpu is like a university professor and a GPU I’d like a room of 1000 children. The professor can solve difficult problems but he can only really work on a small number of things at a time. The room full of children can solve lots of simple problems very quickly, in the case of a GPU normally those problems are simple arithmetic.",
"The Mythbusters crew did a demonstration of this for Nvidia a few years back. They built a \"CPU\" using a paintball gun mounted on a servo gimbal so they could aim each shot perfectly and paint complex images on a canvas. Then they built a \"GPU\" which were just a bunch of tubes all in parallel all with their own paint ball but the air hoses all went to one big trigger and there were no servo gimbal at all. And using this they were able to paint an entire picture all at once with just one trigger pull. This was a good demonstration because each core in a CPU is a lot more capable and is able to act on its own individual instruction thread. However a GPU have hooked up a lot of much simpler cores that shares as much as they can and all act on the same instructions together (but on different data).",
"I suggest you look at [this]( URL_0 ). Keep in mind that Leonardo 1.0(see vid to understand what I mean) is more \"dynamic\" in the sense that it can move around, be reprogrammed way more easily etc., while Leonardo 2.0 can only do one thing: put paint on a surface as fast as possible. Obviously it's much more nuanced than this, but you asked for an analogy, so here it is."
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o42ofp | What is shallowing hypothesis ? | Other | explainlikeimfive | {
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"Me answering this on reddit is a pretty good, albeit, loose example. I tell you that it's digital media's power to tell you the answer to a question you would have sat on the toilet and thought about (coming your own hypothesis) and now you won't sit on the toilet and think about it because you read it here. It's basically the notion that now that information is so easily accessible, people don't come to their own conclusions anymore. Why think when you can google. But it's a double edge sword that leads to wide spread misinformation, uncanny valleys, but also a wealth of amazing knowledge from all around the world."
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o43dzn | What causes black rings to form under your eyes when you are tired. Is it your body’s natural response to give you a hint to go to sleep or is it a nutrient deficiency | What actually causes it. | Biology | explainlikeimfive | {
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o43wgg | What is the difference between 5.1, 7.1 and 3D audio and which is better? | I see alot of these terms being used when selling headets and also used by game developers, but never really knew the difference between them. | Technology | explainlikeimfive | {
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"It all pretty much only describes your sound setup and therefor what kind of sound processing you want to take place. Ignoring 3D for a second cause honestly I don't know much about it. But 5.1 and 7.1 is pretty much the same thing with it describing your speaker setup. The .1 is the subwoofer in both setups. A 5.1 Would have a center front, left and right speaker + left and right from behind. And a subwoofer. A 7.1 sound system is pretty identical with speaker directly to your sides as well. 3D sound would in addition have sound coming from above and below. 3D sound as a concept means sound can come from any direction really, so it's generally achieved by fooling your brain into thinking sound comes from one direction or another and isn't \"true\" sound coming from all directions.",
"The problem you're going to have is trying to define what better means. I used to be really big on surround sound but for the past few years I've found it really distracting. So a good 2.1 system that's cheap is going to be better for me than a 5.1 or 7.1 system no matter how amazing. If you're a professional gamer and want to hear a gunshot coming from behind you so that you can respond then yeah maybe it is better. But that probably depends a fair bit on what games you're playing. I would also guess (though I'm no sound engineer), that a headset that kicks ass at left and right (and that's it), is going to do a lot better job for sound quality than a headset that is trying to bend and play with sound waves to make sound appear to be coming from different directions. Kind of like how a cake is going to taste better if it isn't coated in icing to try and make it look like a unicorn jumping over a rainbow. Which is the better cake? Well if you care about taste then plain is the way to go. If you care about how it looks then maybe the unicorn jumping cake is better.",
"> when selling headets In the context of headsets, there is no significant difference between those terms, and which headset is better has little or no relation to which one is used and is partially subjective. When selling surround sound speaker setups, both 5.1 and 7.1 refers to the number of speakers you're getting: the number before the . is the number of mid and high frequency speakers you'll place around the room while the number after is the number of subwoofers. \"3D audio\" is another term that doesn't have a \"hard\" meaning, but it could be used to describe the software solutions some games - especially VR games - use for giving you vertical audio cues such as \"shoulder reverb\" when the source of the audio is above you. Not that I'm actually certain any VR games do that, could be it's just my subconciousness keeping track of terrain and noticing stuff out of my peripheral vision."
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o4681y | How come, given we hear ourselves differently from how we think we sound, we can reproduce musical notes accurately by singing, just by ear? | I mean, shouldn't we be slightly out if we hear ourselves and think we've hit the note? Same goes with mimicry, I guess... If we think we are replicating a sound of someone's voice, wouldn't it be different to everyone else hearing it? | Other | explainlikeimfive | {
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"So, there are sort of two different things going on here. Nobody sings a single musical note, note really. When we sing, speak, or play a note, there are a bunch of different pitches that blend together. These give us the tone or *timbre* of the note. The thing we think of as the pitch of the note is the lowest or *fundamental* note. When we hear ourselves speak live vs in a recording, we don't hear a different note. Instead, we hear a different *tone*. The notes are the same, but the version we hear internally has more of the lower parts that make up the tone. But the lowest note is still the same one. TLDR: we hear ourselves sing the same note but with a different tone. Harmonising is about the note, so the tone doesn't really matter.",
"You hear your voice differently because of sound reverberating through your bones and being picked up by your ears through your skull. When you’re singing, you are trying to hit a specific note. You know you’re on because you hear the note being played, then you harmonize with that note that you’re hearing with your voice. Your ear can be trained to hear harmony and what is called “intervals” (the distance between 2 notes). Practicing pitch matching with your voice and practicing interval matching will train you to both hear what a harmony is supposed to sound like and feel what you need to do in your stomach/throat to match that sound. Then, when you do it on your own, you just mimic those feelings to produce the notes.",
"We generally don't. Lots of untrained singers \"push over the top\" either harmonically (because it sounds fuller to them) or just slightly (because of what you said). Try hitting a long, steady note, then cup your hand around the back of your ear. That helps you hear yourself, and — unless you're a natural virtuoso — you'll be surprised how much you're off by. It's an old trick used in both training and in practice."
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o47uic | How exactly does Mentholatum clear one's sinuses? | I hope I picked the right category! My sinuses started going berserk, yesterday(as they're prone to do during abrupt weather changes or seasonal changes), and, as usual, some mentholatum rub just under my nose generally gets right to work at least opening things up for me to breathe more easily...but I've always wondered just what the mentholatum is actually *DOING*? Thanks! :) | Chemistry | explainlikeimfive | {
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"Is this like Vicks vapour rub? I'm also suffering currently and can't find anything that's works..so much pressure built up its getting unbearable",
"Holy Google vomit. The ingredient you care about is camphor oil. It relieves congestion. I knew that much and decided to see if I could find out the rest. However, if you want to find out why it works, good luck. Googling that just turns up a thousand essential oils websites. I didn’t even bother clicking those."
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o4842d | How is it that tattoos last a lifetime, when the body replaces most of its cells roughly every 10 years? Wouldn't the dying and creation of new cells remove the solidified ink over time? | Biology | explainlikeimfive | {
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"The way an artist explained it to me is that the ink sits between the epidermis (outer layer of skin) and the dermis (the base layer). The molecules of ink are just the right size to so that they aren't absorbed by the dermis or ejected by the epidermis, so they just stay there, between the 2 layers forever.",
"Check out [this image]( URL_1 ) and ignore all the labels but the ones on the left that say \"Epidermis\", \"Dermis\" and \"Hypodermis\". Now check out [this image]( URL_0 ) where the tattoo needle is injecting ink into the Dermis layer. So the Dermis has cells in it, but it's not *made of cells*. Instead, it's made of a bunch of stuff that we collectively call \"connective tissue\". These are protein scaffolds that hold all of our bits together. These proteins are made and managed by cells in and around the Dermis, and those turnover just like most other cells in the body, but foreign stuff like ink just sort of... sits there. But that's just the ink that stays there. At first the wound weeps ink (if you've ever gotten a tattoo, part of that gross stuff that's under the bandaging is ink that your body is rejecting and pushing out). And over time the body still recognizes the ink particles as foreign and tries its best to deal with it like other things in the immune system by capturing it and bringing it to lymph nodes where the body just... doesn't know what to do with it so it just kinda hangs around. See [this picture]( URL_2 ) (not really NSFW, but if you're really squeamish maybe don't click) of dissected-out human lymph nodes with tattoo ink stuck in them. I can attest to finding multicolored ink-laden lymph nodes in cadavers during anatomy dissection in med school. But this is really slow and inks are safe nowadays where there isn't much safety concern from an ink-retention point of view (risks are more associated with shady folks who reuse needles, body fluid exposure, infection, etc). TL;DR: Ink is injected into a layer of meshwork structure of proteins and fiber material rather into cells. Cells get turned over and the structural stuff gets reworked around the ink, but the ink sits in that layer generally untouched.",
"The ink is under the layer of skin. The skin that is shed and replaced is above the ink. If you tattoo too shallow then yes it will fade really bad because of what you mentioned.",
"The outer layers of the skin grow and shed. Tattooing uses needles to inject ink underneath those layers.",
"It sits under the top layer of skin but over the bottom layer. Your body does actually break down some of the ink. You'll find (after death hopefully) that lymph nodes actually pick up the pigmentation as the immune system breaks it down.",
"The body is able to remove some of the smaller ink particles as the cells regenerate. The problem is that the cells die and gets replaced one by one and not all at once. So as the new cell replaces the old one the ink is still getting trapped in. It is only rarely that an ink particle is able to move around between the cells and this will cause some fading and smearing of the tattoo over time. But it will not cause the tattoo to disappear in a lifetime.",
"The myth of the body replacing every cell every 10 years is quite prevalent, but it simply isn't true. All cell types have very different lifetimes, and some of your cells live for as long as you do while others live only a few days. For example, your neurons and the immune cells that make up your immune memory stay with you all your life, while your red blood cells only live a few months and the cells at the top of your skin only a few weeks. Your skin itself is made up of three different layers. The outermost, which is the one that sheds all the time, is called the epidermis, and it's made up of mostly very thin cells stacked quite deep. The next layer is called the dermis, and it's mostly made up of proteins (like collagen, elastane, hyaluronic acid...), the cells that make those proteins (which together with the proteins are called connective tissue), and blood vessels and nerves. The lowest layer is called the hypodermis, and it's mostly made up of fat cells. When you get a tattoo, the ink is injected into the connective tissue of the dermis, mostly missing the few cells in there and instead sitting between the proteins, so the lifespan of those cells is not important. Your immune system does come to investigate, as ink is a foreign substance, and those cells literally eat up the ink. Once they do though, they can't move anymore, and so they sit there until they die, releasing the ink. When they do, more immune cells of the kind that are always on patrol come by, spot and eat the ink, and end up stuck themselves. Every time this happens, some of the ink is lost, flushed away by the water that's always circulating between your tissues and your blood, and that's why tattoos slowly fade over time."
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