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m8plwe | Why do imperial and metric units use the same standard measurements for time (seconds) when many other measurements (length/distance, volume, temperature, weight, etc...) are so different? | Other | explainlikeimfive | {
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"A fundamental difference between *time* and other dimensions is that our lives happen to be dominated by an omnipresent and very powerful standard metric of time-keeping: the day-night cycle, and the whole reason clocks were *invented* was to keep track of it. I cannot think of any other unit which had its usefulness defined almost entirely by a similarly important universal reference point."
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m8q6xt | is there is a scientific reason of why kids hate sleep so much? | Biology | explainlikeimfive | {
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"Culture is a big part of it. Turns out forcing people to do something when they don't want to and/or using it as punishment/threat doesn't help them appreciate said activity. (\"You don't want to finish your dinner? You can go straight to bed then.\") Also just being certain it's going to be a problem helps in making it one.",
"I think this is one of those things that people just believe. When babies hit major milestones they tend to go through a rough patch sleeping, the general consensus is that they're trying so hard to get the pieces together or to practice they don't want to sleep. I've had my 3.5y ask to go to sleep when he's ready since about 2, mainly for the odd nap since that's when he dropped them. I think like anything else it varies from person to person. Edit to add there are several factors to successfully putting a child to sleep. They can't be over or under tired. Teething is painful. Gas is painful. Unfamiliar locations can make it harder. Not having a comfort item they love (binki, stuff animal, blanket). If they had in appropriate foods too close to bedtime. More of the difficulty usually lies in anticipating the needs of someone who can't communicate effectively."
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m8qb0l | What exactly is stopping me from making 20 email accounts and referring all of them using paid survey sites/apps to get loads of points? | Technology | explainlikeimfive | {
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"Nothing. Typically those sites/apps have some requirements meant to curb it and make inconvenient though. Such as minimums balance for payout, spend a certain amount, or wait an amount of time. Additionally, many of those sites pay terribly, you're better off just doing an actual job than trying to get points. So, in summary, you can, but it's not worth it.",
"Time. This is actually a thing, its always been a thing, its generally not something most places care too much about, they aren't going to go through the effort to try to defeat this tactic that will cost them a lot of time and money to implement when its an extremely small inconvenience at best. There are various ways to attempt to prevent this, and likely they will have at least some safeguards in place, its just not a big deal to go overboard on prevention of this, you're better off just working on running your company. If people want to find ways to navigate loophole or piracy, they'll eventually figure it out. Put some basic security in place and worry about the rest of your product, not like 3 guys doing something awkward when you have a customer base of 100,000 people. To take it to another level, a lot of time, \"free trial\" stuff people just rotate around email addresses and such over and over, but eventually it just gets to be a burden enough that most people stop doing that. Its something that is more common to find in developing countries where there is more willingness to continue spend time and effort to find loopholes"
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m8qlz1 | How do teeth "know" when to come in? | I had my tooth pulled and the dentists were hoping that my molar would come down. Two of my siblings have had to have teeth pulled to let a tooth come in as well. I don't understand how the tooth that's inside can tell there's an opening now | Biology | explainlikeimfive | {
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"The tooth doesn't \"know\" anything. It's just trying to grow the root to push the tooth into position. If there's another tooth in the way it can't. Removing the obstructing tooth lets the tooth do what it was trying to do anyway. It's similar to how you can leave a heavy object on your lawn and flatten your grass, then when you remove it the grass all stands back up. The grass doesn't \"know\" the obstacle is gone, it was always trying to stand up and just couldn't...as soon as the obstacle is gone, it can."
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m8t0s9 | Why animals react weird to mirrors? | Earth Science | explainlikeimfive | {
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"It's quite rare for an animal to be able to recognize itself in a reflection. They usually think it's another animal and get defensive.",
"Most non-human animals are not able to recognize that they are seeing their own reflection. Instinctually, they believe that what they can see must be another animal, and react to it. They are reacting to external stimuli, and don't have the cognitive awareness to reflect on a sense of self. Some animals such as humans, many primates, dolphins, and I believe elephants are able to see a reflection and understand that they are seeing themselves. They have a sense of \"self\" that they recognize. There are likely a number of various species that can do this, but humans are obviously the most familiar to us. In this video, put yourself in the place of the gorilla. It has never seen a mirror before, and is shocked. Eventually it figures out that it is a mirror reflecting, and all is good. Likewise, the chimpanzees here have no problem figuring it out.",
"Recognising yourself in the mirror shows self awareness and is something we deem to be only exhibited by creatures of higher intelligence."
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m8t24b | Why do we feel a tingling sensation when an object is close to our forehead but the feeling goes away when the object touches the skin? | Happens when you point your finger at your forehead or put your forehead very close to another person's, but stops when the skin is touched. What is the biological explanation about it? | Biology | explainlikeimfive | {
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"I get that too. IMO It's a psychosomatic sensation. You won't be able to sense it with your eyes closed.",
"Are you talking about touching the very fine hairs that we, as mammals, have on our skin? If not, I'm unsure of what tingling you may be referring to."
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m8td35 | how do we know the entire universe is expanding, and not just our region of it? | Other | explainlikeimfive | {
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"Totally possible, just very unlikely from what we know now. There's no evidence that suggests that the expansion is dependent on some position, but a ton of evidence that it's everywhere that we looked so far. Nothing we \"know\" is absolute truth. But if a theory matches the observations every time and nobody has ever seen something that contradicts, it's *likely* to be true."
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m8tl7h | Why is nuclear fusion so much more difficult for us to achieve than nuclear fission? | Physics | explainlikeimfive | {
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"Nuclear fission is achieved by bombarding a nucleus with neutrons, so that the nucleus absorbs them and becomes unstable. The unstable nucleus undergoes nuclear fission, spitting out more neutrons, as well as energy. Nuclear fusion is achieved by forcing two hydrogen nuclei (special ones that consist of 1 proton plus 1 or 2 neutrons) to come together and produce a helium nucleus. You have to provide a lot of energy because you're forcing two positively charged particles, that normally repel each other, to get close enough together that they overcome their tendency to repel each other.",
"The basic way to think about it is that with nuclear fission, you have a giant structure that is just _waiting_ to fall apart. You just need to give U-235 a little nudge — in the form of a neutron — for it to break apart. And because it releases neutrons when it does so, it can sustain a chain reaction under the right circumstances. Of course, you need to have the U-235 in the first place — that's where the real \"work\" comes into nuclear fission, getting enough of the right fuel together. With fusion, the hydrogen isotopes don't \"want\" to fuse together. They are repulsed by each other, literally (electrostatic repulsion). If you try to push them together, they'll resist you with greater and greater energy. But if you can somehow get them _very_ close together, they'll suddenly fuse together and release energy. So for nuclear fission, it's like setting up a whole line of dominoes and just starting the reaction. For nuclear fusion, it's about creating very tricky conditions and sustaining them long enough for the reactions to take place. What kind of tricky conditions? Conditions not dissimilar from the centers of stars. We can do this with fission bombs, and that's how thermonuclear weapons work (a fission bomb creates the conditions for the fusion reaction). There are various ways to do this on a smaller scale, but any little imperfection in our schemes and the hydrogen atoms won't fuse. So far the engineering of it has eluded us in making fusion reactions that produce more energy than they take to operate (contrary to some of the comments here, we _have_ achieved fusion under laboratory conditions, but never with net energy production), but the work appears to get closer and closer over time."
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m8tnno | Why is it so easy to make a box so that no light enters, but blocking out sound is much more difficult? This is also in context to my own bedroom! | Do the waves “penetrate” in a different way? Is it about sense perception? | Physics | explainlikeimfive | {
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"Sound operates on a different frequency scale (a million times slower) and so will vibrate through solid objects. Light will reflect off solid objects easier. In contrast to your question, light will travel through a vacuum whereas sound will not."
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m8u1er | Why does an orchestra have many people playing the same instruments? How does it add to the overall performance? | Other | explainlikeimfive | {
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"Generally, the main reason is that having more instruments playing the same part creates a richer sound, but there are multiple reasons that vary for different instruments. For example you have three trumpets, and they often play different parts (different melodies that harmonize with each other) but they can also play the same part, then that melody will usually be heard over the rest of the orchestra. Now, the instrument that there are the most of in an orchestra is the violin. There are usually around 30 violinists. They are usually only divided into two parts (but can be divided further) so you often have 14 instruments on the same part. One of the reasons is as I've mentioned richness, but another is that brass instruments like trumpets are so much freaking louder than strings so having more strings creates a more balanced sound. Edit: typical number of violins. Edit 2: clarity",
"An alternative answer to the others, most of which assume the musicians are playing different parts - when playing the same part, it adds a more layered/textured effect, like a “chorus” pedal for a guitar. When recording guitar, for example, you’d often record multiple tracks of the same part for a fuller sound. Even copying/pasting the same recording but moving one ever so slightly out of sync has the same effect. It makes a huge difference, and without these layers it’d sound quite thin and underwhelming. You could even compare it to a crowd chanting the same song at a soccer game vs one lonesome chap.",
"You place the horsehair of your bow atop the violin string and pull. The rosin effects a friction that causes the string to vibrate. This vibration resonates through the cavity of the violin to produce a sound quite different than the simple sine wave of the string's vibration. It makes a sound that is beautiful and pleasant and musical, reflective of the unique characteristics of the violin's constituent wood and of the exact shape and size of the resonant cavity within. Ten people place the horsehairs of their bows atop their strings and pull. They are all playing the same note. Their violins are the same size--or are they? They are almost the same size, but not quite; the margin of error in manufacturing is small, but greater than zero. The violins are made of different wood from different trees, each with its own voice. Each performer is pulling their bow at a slightly different speed. Their fingers are all placed expertly on the exact spot they need to be placed on their fingerboards, but as the violin is a fretless instrument, each finger is placed very slightly differently to all the rest, offering a barely discernible difference in pitch. The pitch and timbre of each individual tone is unique among the rest. Combined, they are far louder than any one of them could be alone; this is vital in eras before (and venues without) electronic sound reinforcement. But this is not all; combined, they offer variegated and living ideas as to the interpretation of the sterile and static sheet music in front of them. Together, they are something different than they could ever be apart. They are the choir to the soloist; they have crowdsourced greatness.",
"People are missing the obvious. Orchestras predate sound systems. They were the loudest musical event most people in the western world would experience in their life. Several fellow playing the same line is much louder than one and can be heard clearly throughout the venue. The other aspects are side effects.",
"Trumpets are absurdly loud. In a 1:1 sound-off between any given string or wind instrument and trumpet Trumpet would completely dominate. Now imagine you need 5 violins playing the same thing to overcome the trumpet. But now you need 2 or 3 trumpets to play harmony, so now you need 15 violins... look you see where I'm going right? Trumpets (prep you Jean Ralpheo voice) are the WOOORRRRSSSTTTTTT",
"I am the sound engineer for the San Diego symphony. We mic every instrument when we play outside. That is around 80 microphones. There is no way to recreate that symphonic sound through the PA with just a couple instruments of each section directly miced. We have about 25 violins, 14 violas, 10 cellos, 8 double basses, 10 horns, 10 woodwinds, piano, keyboards,percussion, and usually a guest soloist. We run a full Dante rig with a CL5. During the summer at the pops site we use Digico Sd12 consoles with a L’acoustics PA. When inside the symphony hall we don’t mic for amplification (just recording) because the stage walls are designed for acoustic amplification. For recording we do not directly mic instruments. We mic the sections with hanging microphones in an ORTF pattern. In terms of mixing you don’t mix like a normal band. With the symphony everything needs to be even and equal to the other. The conductor is the one truly mixing the symphony. I am there to make sure each instrument is heard by the audience with equal loudness across the section",
"Because they’re not all playing the same notes. It allowed for multiple movements at a time, producing a more dynamic presentation. Or when they are playing the same notes at the same time, it creates depth.",
"And usually, no matter how many violins or tubas you have, you only need one piccolo player. That tiny little flute can dominate the entire band.",
"I’ll explain in an analogy, imagine each instrument as a separate ingredient for a cake. Some are sugar, eggs, flour, vanilla extract, and some are water. The baking is the performance. You need a different combination of ingredients to bake and you need a different combination of instruments for a performance of different kinds of music. Each ingredient on its own is great but the combination of ingredients is what makes a cake so good. You also need way more grains of sugar than eggs. With instruments, you need way more string instruments compared to wind instruments for the orchestra.",
"Same reason a piano has three strings for each note, volume and articulation of the right sound.",
"Another ELI5 question: why are orchestras arranged in a \"asymmetrical\" layout? For example I see that violins are on one side and cellos on the other. Wouldn't a more simmetrical layout be better?",
"Usually those instruments won't be playing the same thing. For example, you might have one set of violins playing the main melody, another set of violins playing a harmony of that, and another set playing a higher/Lower harmony. If the instruments are playing the same part, it's usually a choice to add more of one particular timbre (the sound of the instrument for lack of a better explanation)",
"Many here are explaining the balance for amount of sound produced. I’ll give another reason and analogy. It also helps with the richness of the sound. Imagine a paintbrush with hundreds or more bristles. Each of the bristles is one violin. The type of stroke is very different from one where you drag a piece of cloth dipped in paint across a canvas. Sure you can paint with both, but the texture of the paint will be vastly different from one brush to the next. Each instrument section is like a different brush. They have different colors, textures, timbres, sizes/volumes that different artists want to use differently. This is the difference between a string quartet and a string orchestra. The sound quality is vastly different when there are many of the “same” instrument doing almost exactly the same thing but with minor barely noticeable differences in timing, tone, intonation, volume, etc.",
"This is not totally it, but certainly part. In the same way, when you have a crowd of dozens singing something it's sort of greater than the sum of it's parts (many people may be off key etc) having multiple players of the same instrument adds slight variations that makes a sound more \"broad\" and \"powerful\". In audio production some very very very common effects are delay, reverb, and chorus. These are all slightly different, but generally all of them are usually used to take one sound and multiply it in different ways, because it feels more \"full\". A simple example, if you have a bland room with way too much absorption, a single instrument playing is very \"dead\" sounding. Place that instrument in a cathedral, and suddenly the delayed reflections of the \"same\" sound arriving at your ears at all different times turns it into an incredibly deep, dynamic, emotional experience by comparison. Then there's also a matter of chords and the relationship between multiple notes being played at once, and many instruments are best at focusing on only playing a small number of notes (sometimes just one) at once, so having multiple instruments also allows the orchestra to play larger chords than a single instrument could play.",
"The biggest reason is balance. You could have 100 violins going ham on stage but if one trumpet decides she'd like to be heard, she could play over all of them without a huge amount of effort. Theres a (weak and rarely followed these days, but very prevalent before the 20th century) rule of thumb in orchestral composing that the strings are going to be playing 90+% of the time, the woodwinds about 30-40%, and the brass and percussion no more than about 10-20%. Thats because the way orchestras were built then, if that wasn't the instrumentation balance, it would just be the Trumpet and Horn show with violin accompaniment. This is even more pronounced the further back you go, largely because orchestras were much smaller then (25-40 people vs today's 60-80). In a baroque orchestral piece from the early 18th century, the trumpet might have 3 or 4 minutes of silence, then a couple bars of playing something to accentuate how big and exciting the violins sound, followed by another 3 or 4 minutes of silence. The other reason is color and acoustics, especially for strings. Instruments in the violin family have an incredibly complex sonic profile, also known as the timbre or color. Basically, timbre is what makes a violin sound like a violin. (Fun fact: a flute in the upper register has a timbre very very close to a pure sine wave, which is the simplest form of oscillation). When you have multiple string instruments playing the same thing\\*, each of those complex sound profiles combine to create a rich, lush bed of sound. None of them are matching the others timbre or pitch *perfectly exactly*, so you get this great chorus effect of a bunch of sound all hovering and kinda shimmering in the same place. If you've ever watched an orchestra play, you'll notice that the string players are all wiggling their hands back and forth -- thats called vibrato. The more they do it, the more the sound wobbles back and forth, and the more rich the sound the entire string section will produce. Pay attention the next time you're watching an orchestra: the more intense and emotional a section is (not necessarily loud!), the more vibrato the strings will use, and vice versa. There's nothing quite as dead-sounding as a string orchestra playing without any vibrato at all. Thats part of why composers have them playing all the time -- its like a pad synth in EDM; you probably don't notice that its there, but you'll definitely notice when its not because it'll feel empty, hollow, weak, or unstable. Strings are great to put in the lead because they are so rich and versatile, but also great to have as support because they provide sonic presence without dominating the actual lead. Trumpets and any other (cylindrical\\*\\*) brass just can't do that; they're too bright and too piercing, no matter how hard they try to mellow out and play quiet. \\* Side note: if you're ever writing for strings, never ever have two of them play in unison. One is fine; they make for great solos. Three or more is fine because they start to have that nice chorus effect I described above. But with two playing in unison, they will never be able to match the other's pitch, and even the wobbliest vibrato in the world won't save them. \\*\\* There are two types of brass instruments: cylindrical and conical. All brass instruments have a conical bell (the end) in order to project the sound, like a megaphone, but the shape it takes from the mouthpiece to the bell can either be cylindrical aka the same diameter or conical aka gradually getting wider. Cylindical brass have a much brighter, more piercing sound, while conical brass tend to be mellower and full in tone. Both can play very loud though, so don't mistake mellow for quiet. Examples of cylindrical brass: trumpet, trombone. Examples of conical brass: French horn, euphonium, tuba."
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m8u7hk | Is there a limit to how much information to how much information can be stored in the human brain? | Double wrote that but whatever. I’m asking about a storage limit for the human brain like gigabytes on digital storage | Biology | explainlikeimfive | {
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"You can't really rate the storage of the human brain in these terms because all of your memories are stored with a form of lossy compression. As a result, there is no theoretical maximum amount of information you can store - as long as you have a sufficient tolerance for inaccuracy. Moreover, your memory is associative by nature. What this means in practice is that you're likely very, very good at remembering certain things but terrible at remembering others. Think of the kid who can tell you what every single Pokemon does - but can't remember who the 9th President of the U.S. is. The amount of information contained within the data set of 'every Pokemon' is far greater than the amount of information contained within the data set of 'Presidents of the United States' - but there's a lot of associations you can draw between various Pokemon that permit you to compress that data set to extreme levels.",
"Stored, no. Recall and pulling the memory seems to be the greatest issue for people. Think about when you “forgot” something, then remember it. It never left, but your ability to recall memories can change or be affected over time. Computers are amazing at recall, but realistically fairly limited in storage capacity relatively",
"You can theoretically store infinite information in just one neuron. That's because neurons are analogue electrical devices. It can fire all charge it has, not fire anything or fire something in between. If we say neuron firing is 1 and not firing is 0, you can split 0 to 1 into infinite amount of small segments. Say 0.42 means one thing, but 0.318294 means another. The problem is that the smaller segments you choose the more susceptible is this signal to noise. If some small EM enviromental noise changes your 0.318294 to 0.318295 your original information is lost. As a conclusion the answer to your question is that there is a limit how much information can be stored in brain. But this limit is not clearly definable. It depends how much EM noise we tolerate and how precisely we want to store that information. We'll probably never know a general answer to this question. Each brain is similar in broad strokes, but very different. It's like we're running with CPUs each with entirely different architecture."
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m8udfc | what exactly is disk defragment on computers do? | Technology | explainlikeimfive | {
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"Imagine a messy room where everything is thrown all over the place and u have to run to different places to get everything u need. When u defragment the computer is putting things back where they are supposed to be so it's easy to find Edit my best explanation: Pretty much. If u haven't defragged in months you will usually notice a speed boost when opening things. Imagine u have a messy room. U want to play monopoly but instead of putting everything back in the box, u just literally threw it into your room. And stuck the box on a shelf so u know where it is. Now when u want to play monopoly u got to search through your messy room looking for all the pieces. Each piece tells u where the next piece is, but u still have to go-to that spot to find it and the instructions where the next piece is. Sooo u always know where the box to monopoly is in ur room. The box tells u where one of the dice is, that dice tells u where a chance card is, that chance card tells us where another chance card is, which tells u where boardwalk is, which tells you where the board is etc etc etc. So ur running around diging through things playing treasure hunt just to play monopoly. Defragging puts all the pieces to monopoly in the monopoly box on a shelf where it is supposed to be in the room."
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m8uv51 | How are we able to predict the weather ahead of time? | Earth Science | explainlikeimfive | {
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"Past observation of similar weather patterns and convergence extrapolated into future forms based on known measures (e.g. rising or dropping pressure, speed of movement of high/low weather patterns) etc."
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m8v2nu | how have kings retained power without divine right? | Lords under their rule could form alliances to take down the king and appoint a new one, unless they had a reason to follow the king. How do kings motivate them to follow his command? I can’t really wrap my head around this lol | Other | explainlikeimfive | {
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"Kings don't rule alone. They needs the support of civil society to stay in power. That can include the military, police forces, tax collectors, etc. So long as the king keeps those people happy, it's relatively easy to stay in power. Here are a couple of great videos that explain more. [The Rules for Rulers]( URL_0 ) [Death & Dynasties]( URL_1 )",
"Supporting the king was a good way to become rich. If you fought for the king, you could be rewarded with land and title and never have to worry about money again. Or, you could marry their daughter, and thus your grandson might be the new king some day. You could try to take down the king, but if you are living comfortably, then why? The king would have to make sure that enough people though that the risk of a overthrow was not worth the possible reward.",
"Most European nobility these days are just figureheads and barely influence the government. It was basically a compromise in the shift to a democratic system to have them be still there, still noble, but not the center of authority (many have no authority at all). The reason they're still around is... complicated. Usually a combination of nostalgia, tourist money, historical and cultural connections, and bureaucracy dragging its feet. I believe most royal rulers in Islamic countries claim relation to Mohammed, so they do have a divine right in that sense. In general, autocratic rulers generally buy or suppress whatever opposition there is. They restrict the press and monitor and suppress the other upperclass, influential, and/or powerful people. This makes it hard for lords/nobility/the masses to oppose them. Perhaps you're speaking to a specific ruler though! I might be able to explain more if you have a particular person in mind."
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m8ver4 | why can’t we just decide to go to sleep? like turn our brains off manually | probably a really dumb question but think it’s messed up that in order to fall asleep we have to pretend we are until we trick our brains or something, why can’t we just do it? like flipping a switch? | Biology | explainlikeimfive | {
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"Its an evolutionary trick. The brain wont shut down until we are sure we are safe. Unfortunately real danger has been replaced with worry",
"Really as an adult we \"forget\" how to fall asleep. The trick really is to clear your mind and relax. This used to come naturally when you were younger, but now you have the stresses of being older which make it harder to relax and let go of. If it helps I have some tricks on how to get to sleep easier. The big trick I've found is you need to \"practice\" going to sleep. When you go and lie down in bed, don't do anything else. Don't lie there and reflect on the day's events, don't read a book, and certainly don't look at your phone or TV. Remove those from the room if possible. Get in the habit of bedtime is sleep only. If you lie down on your bed you only sleep. You have to be strict with yourself. Next is a sort of form of self hypnosis. When you lie down to go to bed, think of a trigger phrase. Something pleasant, but which you wouldn't say normally. Good night sweetie to yourself or something. Whatever it is just make sure it is unique and pleasant. This becomes a sort of hypnotic trigger which will tell your mind know you are trying to sleep. Finally relax. Flex and release your body muscles starting at your head and going all the way down to your toes. This will help you relax and fall asleep. Most important though, clear your mind, if you start thinking of something catch yourself and clear your mind again. Eventually this will become habit and you should be able to just fall right asleep.",
"You ever get bored and sleepy? That's how it's supposed to work. If you're stressed or preoccupied, your brain knows it shouldn't be sleeping. Clearly there's a tiger nearby and laying down is a bad idea, right??? That's what it thinks, anyways. If you're not bored, you shouldn't try and sleep.",
"I watched a video somewhere, the other day, of a guy explaining a trick to fall asleep. He said to close your eyes, and visualize a black chalkboard in front of you. Now imagine drawing the letter A, and the wipe it off the board. Do the same with the letter B, and work your way through the alphabet. Have been doing this for the past week, and I end up falling asleep within 10 minutes or so. Most of the time I trail off, thinking about something else, and come back to it, but the “trailing off” is my mind shutting down.",
"Evolution made us weird! I’d 100% rather have an intelligently designed body. Normal backbone for standing, controllable heat, not addicted to fat and sugar, and maybe even a brain that doesn’t over react to literally everything",
"I mean, it *is* possible to turn your brain off manually. You just might not be able to turn it back on.",
"keep the fan on 5th speed (variable resistor) and just jump from below facing backward from fan so it hits your head from back where there is memory lobe and it can take rest.",
"I turn my brain off manually on a regular basis. I usually use name brand alcohol, but sometimes I use off brand alcohol as well, which is often just as effective. Sometimes I just force myself to stay awake for days on end, knowing that my brain will eventually surrender and sink into the sweet embrace of oblivion out of sheer total exhaustion. & #x200B; Glad to have helped!"
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m8vq5x | how do sounds travel down a phone? How is it the noise from my voice is transported and heard miles away? | Technology | explainlikeimfive | {
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"A phone is two parts, a microphone that records your voice and a speaker that plays back the voice from the other end. A microphone works by having a tiny diaphragm that moves back and forth when a sound wave hits it. There is a coil of wire attached to the diaphragm and a magnet surrounding the whole thing. When the coil of wire moves inside of the magnetic field, a current of electricity is created in the wire. This current is amplified and sent down the electrical wires all the way to the person you are calling. On the other end there is a speaker in your friend's phone that works the opposite of the microphone in your own phone. The current of electricity causes the diaphragm to move inside of the magnetic field and it recreates the sound wave that was originally your voice. Modern phone systems have a few extra steps where the electrical current is measured and converted into a digital signal. That digital signal is what is actually transmitted over long distances but it's converted back into an electrical current before it reaches the speaker on the other end.",
"Sound is converted to voltage on a wire. The changing voltage is digitized into a string of numbers. The numbers are sent to the other end of the call where the process is reversed."
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m8vura | if European contact wiped out native populations in the new world by bringing diseases that natives didn't have resistance to, how come Europeans weren't wiped out by native diseases? | Other | explainlikeimfive | {
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"There is a YouTube video that explains the core reason excellently. URL_0 TL;DW version: The Americas didn't have the massive collections of domesticated animals like Europe, Africa, and Asia did. Domestication increases the chance that a disease will jump from animals into humans. The more species you domesticate the more types of viruses can make the jump to people. Also, the European model of animal husbandry put the animals right into major cities with practically no sanitation. Feces commonly in the streets until rain washed them into a convenient stream or river, slaughteryards were often as close to people as possible to avoid spoilage from transport. Most American cities of the time had full sewage systems, or relied on regular canals to move sewage away, and with few large domesticated meat species (alpaca in South America, but those were primarily raised for wool rather than meat) animal slaughtering was far less industrialized. Your local butcher would probably take care of the animals (rabbit and small fowl mostly) in his shop for days or weeks before slaughter, slaughter only what he'd need for the day's sales. This reduces the amount of waste and spoilage, as well as making it so that animals that were ill were LESS likely to be harvested for food, and therefore less likely to spread those diseases to humans.",
"There were some diseases that were sent back from the New World to Europe such as syphilis. But, there weren't any devastating plagues from the Americas to send back. These sorts of diseases require cities to thrive. Without a large population of people, any really bad disease will burn through a tiny village and have no one left to infect. Then the disease will die out. The New World didn't have a lot of very large cities to act as incubators for plagues. Here's a great video with more information [Americapox: The Missing Plague]( URL_0 )"
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m8wij3 | why does soda or other carbonated beverages foam up when poured over ice? | Physics | explainlikeimfive | {
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"Common ice cubes have uneven surfaces. When carbonated water touches those bumpy surfaces, it gives something for the carbon dioxide to cling to. The bubble eventually grows large enough that the upward pull causes it to lose hold of the icecube, float to the surface and break! Before it breaks, it causes the foam you see."
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m8wu5e | How does our bladder avoid low pressure when we're peeing? | Biology | explainlikeimfive | {
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"When you have a solid tank full of liquid, the pressure gets lower as the volume of liquid gets lower. When you have an elastic container like a balloon full of liquid, as long as it's stretched out, even a little by the volume of liquid, the internal tension on the material trying to stretch back to its unstretched size will keep the pressure pretty high. Think of your bladder like a water balloon, and not a water bottle"
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m8xtjl | how did water appear in Earth and how did we end up with such vast amount of it? | Earth Science | explainlikeimfive | {
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"Water is Hydrogen + Oxygen, two of the most abundant things on Earth. Much of the Earths crust is made up of Oxygen, bonded to other things like Iron to make minerals. Since a lot of Oxygen existed on the primeval Earth, and Hydrogen is the most abundant thing in the Universe, having water was inevitable. So where did it come from? Either the Earth was formed from material that contained a lot of Oxygen and Water, or the early Earth was bombarded with Comets and Asteroids that contained Oxygen and Water.",
"Water is really common in the universe. It's made of hydrogen (by far the most common element) and oxygen, which is made by stars and not very rare either. Water is found on/in all the gas giants, on many moons, and most/all objects out near pluto, in the Kuiper belt. I don't know if we do have a huge *amount* of it; some moons of Jupiter and Saturn have tons and tons of water ice. Mars had a huge amount of liquid water, but it's all either frozen or swept away now that the planet has no magnetic field (along with its atmosphere). Venus probably lost whatever water it formed with to solar wind in the same way.",
"\"Vast amount\" is a relative term here. The total amount of water on Earth is still only about a millionth of the total volume of the planet--by any normal measure, that would actually make the place rather dry! It's just because our atmosphere and temperatures mean we have liquid water on the surface that it's quite so obviously part of our world.",
"We're not exactly sure, but a leading theory is asteroids with water bombarded the Earth and provided the bulk of the water, with a significant fraction coming from comets and maybe 1-2% from the solar nebula (the disc of gas surrounding the sun).",
"Once upon a time, there was hydrogen, and it came together because even though it's a tiny particle, it still has mass and gravity, and more and more gathered together into a star. That star got so big and heavy that it started to mush the hydrogen atoms into helium, and then helium into lithium, and so on. And at some point, that star became unstable and exploded, filling the surrounding space with all kinds of planet stuff. Some of that planet stuff included hydrogen and oxygen, lots of it and as we know from fire, hydrogen and oxygen mix pretty easily when an ignition source is involved. Boom! Big fiery reaction... and the hydrogen and oxygen are now... you guessed it, together as water molecules!"
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m8ydwb | What is special about some bricks and charging cables that make my Google pixel 2 phone "rapid charge"? | Some brick/cord combinations make it charge but not say "charging rapidly" and others make it tell me it's charging slowly and I should use the ones that came with it. | Technology | explainlikeimfive | {
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"Fast charging requires a device and charger that are rated for higher amps. Amps is essentially a measure of flow, more amps mean more electrons moving. The device determines if it can fast charge or not, but it needs an adaptor capable of delivering the extra juice it needs. I've actually heard a bit recently that fast charging does have a negative effect on the longevity of the battery. If you have multiple chargers, some fast and some slow, it's better to use the slower chargers overnight and save the fast chargers for times when you really need them. I bought one of [these USB charging monitors]( URL_0 ) a while ago and it's kinda cool to see what your USB chargers are actually doing."
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m8ymd7 | How do archaeologists know when to stop digging? Couldn't there be many more dead sea scrolls if they just keep digging up more of the area? | Other | explainlikeimfive | {
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"Archaeologist here. I can’t really speak to this project. As the other person said, yeah the dig usually ends when the funding blows out. But that said, ethics dictates you always leave at least some portion of a site undug. The reasoning is that some day in the future, someone might come along with far better methods and technology than what you have available, so you want to leave them something untouched to study. If people hadn’t at least sometimes followed this rule in the early 20th century, we would have lost a lot of stuff that can now be dated by radiocarbon and other means. It’s also why I’m reluctant to wash excavated artifacts any more than is absolutely necessary, and I always keep a portion totally unwashed. Who knows what kinds of residues or other data someone might be able to pull from that 50 years from now.",
"If I'm not mistaken, the Dead Sea Scrolls weren't dug up. They were found in containers inside of caves. There is an Israeli archaeological project under way to explore more of the caves in the area.",
"I work in western Canada, we stop when we reach sterile sediments which we interpret as glacial deposits because people weren’t here before glaciers.",
"Generally they stop digging when the funding runs out. Although they can also take some reasonable guesses as to whether an area is likely to be worth the time. If they're digging in an established area and they see signs that they've reached the edge of the habitation, either in area of in time, there probably isn't much point in continuing to dig. There *might* be--there could be an adjacent settlement or one that existed earlier in time--but the chances are lower. It ends up being a bit of a judgment call. When establishing a new dig area, they typically conduct a number of different surveys to try to predict where they'll most likely find something. Satellite photos have become very popular for this but other methods exist, including picking an area and digging some random test holes.",
"Archaeologist here. We know it's time to stop digging when it's about 5pm. Beer doesn't drink itself.",
"They can tell when they have reached the natural, undisturbed ground or bedrock, when they know there is no point in digging further because there can't be anything there.",
"I actually know a woman who works on the Dead Sea scroll digs. She’s one of very few experts on the Dead Sea scrolls in the US (might be the only one? I’m not sure). The Dead Sea scrolls are kind of a special case when it comes to archaeological digs because there are looters in the area who are after all the same artifacts that the archaeological teams are looking for. There’s literally a race to find the Dead Sea scrolls because whatever the archaeologists don’t protect, the looters will sell on the black market. It’s some Indiana Jones shit. Edit: here’s an article about it URL_0"
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m8z96j | Why are things you aren’t meant/allowed to go often much more fun? | Other | explainlikeimfive | {
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"Evading getting caught can be fun because hiding it feels like a game of skill, and you are winning. It’s the same psychology as hide and seek, but with higher risks."
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m8zm8m | Why does the crypto market fluctuate so much every day? | Economics | explainlikeimfive | {
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"There's no governmental power keeping it stable like other currencies. It quite literally is only worth what people think it's worth.",
"It is a very small market. Fluctuations will occur with much smaller movements of money than in our bigger stock markets. Plus the supply of tokens is variable, being mined and burnt along the way, meaning the 'number of shares' is ever changing."
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m90fb1 | If you can't sleep so you lay still for an extended period of time with your eyes closed, does that do anything to restore energy? Or does the fact you're still awake make it a useless gesture? | Biology | explainlikeimfive | {
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"When you are laying at night with your eyes closed and relaxed, but you feel awake, you may actually be in the first stage of sleep. People who go for sleep studies can report that they didn't sleep all night but when their brain wave activity is analyzed, they were going in and out of light sleep.",
"Resting would, I think, have a similar effect on the physical recuperation side of things, but wouldn’t help with the mental aspects of recovery that sleeping provides.",
"Eyo neuroscientist here! You’ll be producing slower waves of neural activity (alpha waves) as you rest, but this is not nearly as slow as the waves you get in deep non-REM sleep. So, yes it would be better than being completely awake, but it wouldn’t have the same effect as sleep. Hope this helps!",
"I find it helpful. I stay in the dark, and don't do screen time. Music in the background is good for me though. The hardest part is not to be anxious about why am I not sleeping and how I will feel tomorrow. As long as I stay calm and relaxed, I usually feel well rested afterwards.",
"It doesn't really do anything to restore energy, more that it slows the rate at which you use up your current energy reserve, so if the goal is to ultimately recharge your batteries it is pretty much a \"useless gesture\". There's some discussion around the idea that a deep meditative state can give the feeling of energy being restored, but it's not really been proven scientifically, it's likely more a perceived effect not unlike a placebo.",
"I would imagine it's better than being awake and alert, but worse than being fully sleep how big that gap is and which one it is closer to is a mystery to science"
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m90lg4 | An actual five year old probably wouldn't understand this but how come irrational numbers can never repeat or be fractioned? | There are an endless digits in irrational numbers, so theoretically, shouldn't there be some point where the digits repeat? Edit: ok I realized that I worded this very poorly, what i meant to ask was how do we know an irrational number is truly irrational, and that there's no pattern that will ever appear in the number? Maybe the first ten digits don't but the first 100 digits are, or maybe the first 1000 and so on. | Mathematics | explainlikeimfive | {
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"Irrational doesn't mean there are no repetitions whatsoever - that would be impossible. When you write a rational number as a decimal fraction, you either get a finite fraction (such as 0.12) or an infinitely repeating fraction (such as 0.12121212...). With an irrational number, if you write it as a decimal fraction, then you won't get a part that repeats infinitely. For example, the number 0.01001000100001000001... has a lot of repetitions, but isn't infinitely repeating fraction, so it is irrational.",
"Irrationals, by definition, cannot be fractions. So how do we know an irrational cant ne a fraction? Well, by definition. I feel like you are more curious about 'how can we tell a given number is irrational?' And that depends on the number. You can easily prove sqrt(2) is irrational. Other numbers, like 'pi + e' we havent fogured out yet. > Maybe the first ten digits don't but the first 100 digits are, or maybe the first 1000 and so on. True. For example, an outstanding question in mathematics is 'is pi + e rational?'",
"Addressing your question you specified in the edit, we pretty much have to check for every irrational number. And we have a variety of different proofs we can use to do that. For example, we can prove that the square root of 2 is irrational. But doing that doesn't also prove that pi is even. You need to go do that on its own (which we did). & #x200B; Btw, the term you are looking for is \"prove\" proofs are a huge part of math. Where we prove without any doubt that a certain thing is true (or not true).",
"It doesn’t mean that no digits occur more than once - for instance .1122111222111122221111122222... never repeats. Think of it as periodic. The big picture is to show that a number is irrational, we prove that it isn’t rational.",
"I momentarily can't remember the part about the repetition, but as for the fraction: that is, by definition and their name, what makes them different from rational numbers. If you were to find an irrational number that can be written as a fraction, it is a rational number, not an irrational one.",
"Well, for the first part, because anything that DOES fall into an eternally-repeating bit somewhere down its decimal expansion? Can be expressed as a fraction. {Say the number is I. a) Multiply I by 10 enough times to get to where the repeating part starts right at the decimal; remember how many times, N, that was. b) Note down what the integer to the left of the decimal now is, D. c) Figure out how long the repeating part is, how many decimal places: M. And note down what the integer is that makes up the repeating part, F. Then I is the fraction ( D * ( 10^M - 1) + F ) / (( 10^M - 1) * 10^N ), which is one integer over another, so clearly is a fraction.} Of course, this pushes the \"why?\" to the second part ... and there, the reason an irrational number can never be an exact fraction is because all fractions are \"rational\" numbers by definition: they are the \"ratio\" of two integers, one divided by the other. \"Irrational\" numbers are numbers that aren't rational. Now, irrational numbers CAN repeat bits and pieces you've already seen further up their expansion ... there's only 10 digits to use in base 10, and only 10^n combinations of them that are n digits long, after all. They just can't keep on repeating one particular sequence forever-and-ever. --Dave, now ask about \"transcendental\""
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m90qkz | Why are Diamonds the hardest rock but also easy to cut? | So if Diamonds are a 10 on the Mohs scale of hardness which I understand they're super hard then why are they so easy to cut? After all shouldn't the hardest rocks be really hard to make jewelry and rings out of? How can you cleave or shear a diamond if it's so hard? | Chemistry | explainlikeimfive | {
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"They are not easy to cut by abrasion, but their crystalline structure allows for them to be cleaved. Most diamonds that end up on jewelry are not so much *cut* as *polished* on the surface of a diamond wheel which has been impregnated with diamond particles. The massive diamonds are essentially ground down to their final form, facet by facet. It's all about geometry and abrasion.",
"There's a difference between hardness and toughness. The harder the material, the less tough it is. Hardness is basically a measurement of how well something can scratch. If you rub a rock against a diamond, the rock will be shaved, though if you take the rock, and drop it on diamonds, the diamonds will shatter. As for cutting diamonds: The way the atoms are arranged make for weak points that you can use other diamonds, and high pressure water to cut."
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m90qrh | Why does red look like green? | I have protan-type colourblindness, and it is often referred to (along with Deuteran-type) as “red-green” colourblindness. Why is it specifically red and green that get mixed up? | Biology | explainlikeimfive | {
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"The human eye has 3 types of light-sensitive cells. Some are sensitive to red, some to green, and some to blue. If you have protanopia, you either are missing or there is otherwise some dysfunction to the cells that detect red. However, these cells aren't binary. They do react in different magnitudes to light. Imagine a spectrum with red at the far left, blue at the far right, and green in the middle. The sensitivity of your cone cells are like little bell curves that peak at their corresponding colour. So, even if we call it a \"red\" cone, it reacts a bit to green and much less to blue. Green responds a little to blue and red in similar amounts, and blue responds a bit to green and a little to red. On top of that, there's very little in the real world that gives off a \"pure\" wavelength, so even looking at something that most people would call \"pure red\" is still likely going to have a little bit of blue and green in it. So, whenyou look at something red, the green and blue cells get activated together, you get muddy yellow. Likewise, when you look at something that's green, red and blue would normally both react a bit, but lacking red, you only have blue and green, which is again yellow. The result is that it's very hard to tell if something is green or red.",
"Human color vision spans a range of the electromagnetic spectrum with wavelengths from 400 to 700 nanometers (nm). Your color vision is broken up into 3 different light sensitive cells known as cones centered at blue, green and red colors. The peak of blue is at 445 nm wavelength while green and red are closely spaced with peaks at 530 and 560 nm, respectively. Because green and red cones are so close, any defects in them can shift their color absorption towards one another, causing the common forms of red/green colorblindness.",
"Your eyes have three types of sensory cells, for red, green and blue. Your background in graphics will be helpful to understand how these three are enough to perceive all colours because we are of course dealing with light / additive colours. Any of these cells can be malfunctioning so colour blindness can affect any combination of colours (why the fuck do I keep misspelling it as \"colurs\" goddammit...). It's just that red/green happens to be the most common one, with blue/yellow being second most common. Why these are more common is probably something a geneticist might answer, I'd assume. Edit: or maybe just ask /u/PrionBacon because the wavelength explanation makes obvious sense."
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m917re | Why is it common to see Intel or AMD processors in computers, but no other brands? | Technology | explainlikeimfive | {
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"Those companies have the infrastucture, technology, and knowledge to manufacture processors on computers.",
"Motorola used to be a big processor manufacturer. The Apple II and early Macs ran on their processor. PowerPC was a collaboration between Apple, Motorola and IBM. They could not compete with Intel in horsepower or architectural breakthroughs. Also, Intel aligned itself with Microsoft early on and MS flooded the market with their OS, both personal and enterprise, consequently making Intel an ubiquitous processor. AMD emerged later, and mounted a successful challenge to Intel. Apple just released their new line of non-intel Macs last year, because iirc Intel processors run too hot and consume too much power. They are back to being a player on the market but they are limited by the fact that they are limited to the personal computing space and only used in their products so I doubt they’ll challenge the big 2 for the title.",
"It's very, very, very expensive to buy the tools and experts required to create processors. Thus, it is economically difficult to run a competitor. Source: Dad worked for Cyrix, back when that was a thing. It's also worth noting that the latest Macs don't run Intel or AMD, nor do Raspberry Pis, nor does any cell phone, and I don't know what the current generation of game console runs, but the previous generations didn't use them either.",
"There use to be other brands. I remember a company called Cyrex I think. And there were others. Back in the 90s. But they couldn't complete with Intel and AMD. So they either got bought up or went out of business. In current times Intel and AMD are codependent on each other.",
"A long, long time ago, I can still remember, there *were* multiple Chip companies: Intel, AMD, IBM, Cyrix, … and those were just those compatible with the Intel microcode (the low-level language that actually influences the tiny transistors on each chip). For a time AMD was actually ahead by delivering better thermal efficiency. But here are the problems: 1. If you try to be compatible, you'll always be slower to market 1. If one instruction set dominates the biggest market – consumers – it's hard to make money elsewhere Apple managed to do do their own thing for a while using Motorolla 68k & similar CPUs, and a lot of big iron still had their own stuff, like the HP PA-RISC or IBM with the System/360. But most developers folded, were bought, or moved to other niche chips. AMD wasn't doing so great either, but then they managed to do something that Intel hadn't done: create a backward compatible 64bit CPU & instruction set. Intel *did* create a 64bit CPU – the Itanium – but it wasn't compatible with its other chips and only meant for big servers. That did put AMD back on the board. The big hurdle for new players, at least in this market, is that you'd need to - create the CPU from scratch, and CPU design is not easy - be fast enough to market - have an advantage over both Intel and AMD (performance, thermal, price being the most obvious targets) - find a fabber (chip factory) to actually manufacture them So other systems usually play different fields: - VIA is stil creating Intel-compatibles, but for the Chinese market, probably with big subsidaries from the government - ARM licensed out their design, and those chips are largely used in embedded systems (though there is a growing market for general puropse machines, see Raspberry Pi & Apples M1) - a lot of energy is currently going to new RISC-V systems, an open source chip design - and then there are all the ATmega(-compatible) chips for embedded boards like the ESP32"
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m91ijj | How does your body 'feel' or perceive wind? | Biology | explainlikeimfive | {
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"It's the same way you can feel your computer mouse + keyboard. Wind is just air that's moving around. That moving air creates a force, which slightly compresses your skin. Your skin senses this compression and interprets it as the feeling of wind.",
"Your Skin can detect temperature. Wind disturbs the shell of temperature you are in. Bodyhair is linked up to nerves so you notice how the wind moves your hair."
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m91plf | Why does the body lose appetite when sick (like with the flu)? Shouldn’t it be super hungry as it needs more power to the immense system? | *immune not immense | Biology | explainlikeimfive | {
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"The reason why you lose your appetite is usually nausea. So basically you don't feel like eating because you'll probably just throw it back out. That being said, you should still try and eat when you are sick and keep as much of it down as you can because, as you said, you need that energy.",
"There are lots of reasons for changes in metabolism when you are sick. * Increasing temp as part of immune response * rapid increase in white blood cell production and other immune factors * Body getting rid of stomach and bowel contents in case infected or poisoned food is an issue. There are probably more as well. Then there are the benefits of emptying the digestive tract (in case you have been wounded) to reduce sepsis (internal infection) Then there is the benefit in a competitive environment of hiding away from predators (human and wild) when you are least able to protect yourself and most likely to be the part of the \"herd\" that is culled. If we feel sick we tend to hide in the cave. Add to this that occasional fasting is good for us, so this is a perfect opportunity to reduce our food intake, and reduce the part of our metabolism involved in food gathering, consumption, digestion and elimination.",
"Digesting food uses up energy, energy you are lacking as your body is trying to fight off foreign bodies."
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m91wlk | Why is a movie deemed a failure if it doesn't perform well in the box office but continues to be watched for years? | Other | explainlikeimfive | {
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"Studios make the bulk of their money from early week theatre sales. The theatres and the studios have a unique type of deal. For the first couple of weeks or so (the exact timing is determined by contract) the studio gets all the money from ticket sales, or at least the vast majority. For every week that goes by, the theatre starts to get a larger cut until they start to make all the money from the sales. For example, if a theatre is showing a movie eight weeks after the initial release, the studio might get $0 from that. So, studios need movies to make as much money as possible in those first few weeks. People might keep watching those movies for years, but the studio sees little of the that money."
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m925jv | If cheese can be aged, Why does the cheese slices i buy from my local store have expiration dates? | Other | explainlikeimfive | {
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"For cheese to mature correctly it has to be kept in precisely controlled and monitored conditions, often involving physical interventions like being turned over or rotated. As soon as it is removed from these conditions and packaged for sale the 'disciplined' ageing process is ended and the 'decaying' process begins Edit: you specifically mention cheese slices - these are so heavily processed that they do not undergo any kind of controlled ageing system, coming straight off of an artificial production line"
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m92p7o | why do we see transparent floaters infront of our eyes sometimes? | Biology | explainlikeimfive | {
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"The floaters you see in your vision are made of the debris floating around inside your eyeball. A certain amount of this is completely natural - it is just caused by some of the natural fibers that make up your eye clumping together and floating around, which appears as a small shadow in your vision. Over time these just get absorbed by your body (as new ones appear). These are generally most obvious when you look at a plain background such as a blue sky out plain wall, but they are always there - your brain just tubes them out for you. They are not normally a worry - everyone has a certain amount of them. The only time they are more of a worry is if you see a pretty sudden increase in the amount of floaters you are seeing, and especially if that is combined with seeing flashing lights or a shadow in the edges of your your vision which can be the sign of a more serious problem that needs seen by a professional.",
"Those are baby brainworms, they dont know how to hide yet, but soon you will forget about them"
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m92ryy | How does the volume increase or decrease in a speaker ? | Physics | explainlikeimfive | {
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"When you raise the volume the voltage of the pulse going to the speaker coil increases while remaining at the same frequency the overall power going through the circuit goes up. A speaker is composed of a magnet attached to a diaphragm with a coil around the magnet (or the other way around). It works similar to a brushless motor. The signal your phone gives to the speaker oscillates from positive to negative and this moves the speaker in and out resulting in sound waves. In order to make it louder you need to move the speaker in and out harder so in the signal given to the speaker the voltage of the + and - go up, while still switching from + and - at the same rate or at the same frequency."
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m9330s | Why is physically hacking into game studio's servers the only way to obtain game's source code? | Technology | explainlikeimfive | {
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"When it comes to code there is an important distinction between high level code and low level code. Source code is the highest level code that is available for any written project. Afterwards you translate that code through a compiler which makes it low level code. High level code is meant for people to read. It has syntax that is recognizable to humans and is usually broken up into parts to make working on it easier. Low level code is meant for machines. It is the ones and zeros that tell your computer how to move the rest of the ones and zeros. When you download a game you are receiving that low level code. Its all you need to actually run the program and is far more optimized. The problem is that data is actually lost in the translation process. There are actually programs that attempt to rebuild source code based on machine code, but it can only do so much.",
"The copies distributed out to users aren't human readable code, rather, they are machine readable code that is the output of a compiler. Think of it as the recipe of a cake: you can't always determine how it was made from just having the finished product.",
"> How is it locked from accessing by user? It is compiled. That is it is sent to customers in a language only the computer understands and can logically execute. There are tools to decompile it, but they can't do so perfectly, they usually cannot recover things like variable names and code comments, making code, especially code of that size, very difficult to read.",
"Decompiling code doesn't mean it dumps the code outright, let alone a nice and neat editable format. Decompiling can get you the \"what\" and maybe *some* of the how, but that doesn't mean you'll just get a raw dump of the code as the devs wrote it. Programming is a language - in any given language, there are different ways of saying the same thing. Decompiling is a little like using Google translate, but backwards, except you understand the words that it produces but not what it means in any context. That context and grammer are what you need to make a sentence, and therefore hacks and all that. Edit - Programming languages allow a person to make something on a computer by using a more human-friendly language and interface to turn whatever it is into \"assembly\". Assembly is what the computer can understand directly - some say \"1's and 0's\" but that's just a term for the billions of transistors being on or off. Decompiling gives me a way to recompile that code again, but not in the same way as the devs did, and it's the \"how\" the devs did it that makes hacks and other stuff possible."
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m937jl | Why is it that some phones today have cameras with hundreds of megapixels but advanced DSLRs and Mirrorless cameras have only 64? | What are megapixels? How do they work? What is the difference between a 64mp mirrorless camera and a 24mp mirrorless camera of the same brand? | Technology | explainlikeimfive | {
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"Images are made up of squares of a single color, pixels. A megapixel of course refers to a million pixels, 64 million pixels means 64 million tiny color squares. > Why is it that some phones today have cameras with hundreds of megapixels but advanced DSLRs and Mirrorless cameras have only 64? Because not all pixels are made the same. A digital camera has a sensor, this sensor is divided into smaller sensors for each pixel. While phones can have higher number of pixels, the sensors that absorb these pixels are smaller and thus more prone to error. The sensors on the DSLR are not only larger, allowing them to absorb more light to avoid this error, they also take in more light because these cameras have bigger lenses to get more light. DSLR manufacturers just have little reason to join in these \"megapixel wars\" since their customers know more megapixels doesnt necessarily mean better."
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m946pm | How does a Chameleons colour change work and how does it activate it? Also, is there any colours it struggles with and can it change into colours beyond our visible spectrum? | Biology | explainlikeimfive | {
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"Chameleons aren't the masters of color and camouflage - for that you need to go to the octopus, the cuttlefish and the squid. Chameleon are mostly greens or browns and shift to lighter and darker colors. Some do have red or yellow markings as well and they have UV markings as well. When they get angry or threatened then their color changing goes into overdrive and they go very dark. But Chameleons are born with particular markings / pattern and they can't change those - their color changing is restricted to lightening or darkening their existing pattern.",
"Chameleons use two systems for color change. To explain this first you need to know the way color works in chameleon skin (and really the skin of many animals). There are three kinds of pigment cells. Melanophores basically control how dark or black an animal looks. Iridophores are tiny crystals that scatter light, and based on the arrangement of the crystals, the light scattered can show an array of colors from blue to red. Finally, there are xanthophores which contain yellow and red pigments. Chameleons can expand or contract the melanophores, which causes them to become lighter or darker (basically they either spread out the black pigment into a blotch or concentrate it into a little dot). Lots of other animals can do this too (most fish, for example). But chameleons can _also_ control the crystals in their skin and change what hue they reflect. By controlling both these things they can change or alter their color. Contrary to what you often see on TV, they aren't able to just arbitrarily mimic any color, although they are usually pretty well camoflaged in their resting color. They can change color to absorb more heat from sunlight and especially to make displays at each other. Different species and individuals have different color patterns they display. Think of it less like a camoflage suit and more like one of those billboards which shows a series of ads. Some chameleons have UV markings but I'm not sure if they can change them or not."
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m948pe | Who decides or how is having a unique bank account number designed so that no two bank account numbers are the same anywhere in the world? Similarly, how were country-codes for phone numbers decided? | Economics | explainlikeimfive | {
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"Bank account numbers can be the same. Each bank has a unique code, as long as the account numbers are unique within each bank then both numbers together form a unique reference. Allocating a list of unique account numbers in a bank IT system is relatively easy.",
"The bank account number is not unique globally or even in most countries If you do transfer between banks the system in countries tends to be that you have a back code that identifies the bank the account is located in. The system tends to be national and you can find example [Bank\\_code]( URL_2 ) Some countries have the bank ID in the account number but most do not. There is also an international [International Bank Account Number (IBAN)]( URL_0 ) system that contains a two-character national identity that is [ISO\\_3166-1\\_alpha-2]( URL_1 ) a checksum and then up to 30 letters and digits that is the country-specific system. So bank account does not have a unique number there is just an international way to designate a country and national system to identify a bank, but the last part that is the account number is not unique.",
"Typically, bank cards have 16 digits. The 1st digit represents an Industry ID; 4 for Visa, 5 for Mastercard, 6 for Discover, etc. The next 5 digits represent the ID of the institution (i.e. bank) that the card belongs to. These are unique to the institution. For example, \"4111 11\" might mean that the Visa card (4) was issued by JP Morgan Chase bank in USA (111 11). \"5444 11\" might mean that the Mastercard (5) was issued by Fifth Third Bank in Singapore (444 11). The next 9 digits are unique to each customer from the issuing institution. Two people might have the same 9 digit number, but be from different institutions. The final number is a 'checksum' number to ensure that the previous 15 digits were entered correctly without having to contact the institution for verification. & #x200B; The International Standards Organisation (specifically [ISO/IEC 7812]( URL_0 )) determines which numbers that each industry and institution get."
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m94nch | Why are most cups and glasses designed with a smaller base and bigger top? | My first impulse was that it's easier to hold them like that, but it's also very common among coffee mugs that don't have handles and uncommon among large water bottles. It would seem like a larger base would make a glass harder to knock over, both because of a widened base requiring more force to destabilize, and because of the weight distribution. | Technology | explainlikeimfive | {
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"Aside from stacking, it's easier and more confortable to drink from a glass that widens to the top, than from a one that narrows, you'd have to tilt the glass and/or your head more to finish the drink.",
"Glasses are made larger on top so they stack well. This saves space and make them safer and easier to store and move around."
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m95kmb | How do painkillers work? | Biology | explainlikeimfive | {
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"It depends on the kind of painkiller. Aspirin and ibuprofen for example alter the way your body responds to pain and swelling, codeine blocks off the pain messages from your brain and spinal cord.",
"Imagine a pain cell is like that basketball game at arcades. Every ball through the hoop increases the amount of pain you feel. Certain painkillers just keep the ball from going in the basket. The shots are still coming but none of the balls are going into the basket so your body doesn’t feel the pain. Other pain killers are anti inflammatory medicines. That’s a whole different game at the arcade. Imagine you’ve got a ski ball machine and you have your seven ski balls and the holes. The other 10000pt hole is hard to get through but the anti inflammatory will make all the holes only worth 10 pts. So the body doesn’t respond in like and produce a bunch balls for the basketball game."
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m96mt7 | How does water evaporate without ever reaching 100 degrees celsius? | Chemistry | explainlikeimfive | {
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"Temperature is a measure of the *average* energy of the molecules in a substance. At 100c the energy of the average water molecule is high enough for them to overcome the bonds keeping them in liquid form. Some molecules won't have quite enough, some will have more than enough, but *most* will evaporate, so the water boils. Below 100c the *average* molecule can't evaporate, but the occasional molecule on the surface of the water might happen to gain enough energy to evaporate on its own.",
"If you mean transition to steam, boiling will occur at lower temp with altitude/elevation. At 5000 ft above sea level, water boils at 95 C and so on.",
"Because the water molecules are moving about and some at the surface move fast enough to break away and float off. Heating the water increases the speed of the molecules and increases the vaporisation.",
"Heat in this context is the energy of the individual molecules. The higher the temperature the more energy, and the easier it is for them to overcome their connection to the other molecules. But this can also happen at lower temperatures. Since this effect also removes energy from the system this effectively cools it. To see this in action wrap a bottle in a wet towel & leave it out in the sun for 15+ minutes.",
"The body of water is made of molecules. Individual molecules on the surface can be given enough heat to reach evaporation before that heat transfers to the surrounding molecules. If you've ever swam in a lake, you'll notice that the surface feels nice and warm but a few feet down it can be noticeably colder. Water is not a perfect conductor of thermal energy.",
"100 degrees C (212 degrees Fahrenheit) is the temperature at which the _vapor pressure_ of water equals one \"standard atmosphere\". Breaking that down a minute: liquids usually have a 'vapor pressure', meaning how much of that liquid compound in vapor form is in equilibrium with that liquid, so that as much is condensing into the liquid as is evaporating from it. As might be obvious, as the temperature rises, a liquid's vapor pressure will also rise, and as temperature falls so will vapor pressure. Different liquids have different vapor pressure graphs. Now add in that the atmosphere is pressing DOWN on everything, with the weight of all the air above that stuff; on average, at sea level this is 14.7 pounds per square inch = one 'atmosphere'. (This sounds like a lot. And it IS. But we evolved down here and are used to it, and maintain the same pressure inside our bodies, so there's no net ballooning up or crumpling in. Meanwhile, if you go underwater, every 33 feet down, approximately, is another atmosphere of pressure. Which is why scuba divers take _pressurized_ air or oxygen, in tanks, to breathe with.) Given that, you can see that at sea level, water starts boiling when the internal vapor pressure equals (or exceeds) the outside atmospheric pressure. But even below boiling temperature, it still has a vapor pressure ... and if the humidity ( = water vapor amount in the air) isn't too high, it will still evaporate, though more slowly than by boiling, until there's enough humidity in the air to be condensing back in just as fast. --Dave, fun fact: a liquid's vapor pressure at its freezing point is NOT necessarily zero"
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m96ynw | what does antipsychotic medication, specifically risperdal, actually do to the brain, and what are the long term effectso of it, after a long time (9 months) of taking it? To what degree will the brain revert to its default state after you stop taking it? | Biology | explainlikeimfive | {
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"Why does it say theres a comment but I can't see a comment?"
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m9715f | what can realistically happen if your IP address has been exposed? | Technology | explainlikeimfive | {
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"> What can they do with IP addresses? Send you a message that your router will then promptly ignore. You are sending your IP address to every single website you visit, it's inconsequential."
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m97x4y | Why can't we stimulate human body part growth yet? | Biology | explainlikeimfive | {
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"The body is ridiculously complex and is programmed by DNA to grow to certain proportions before stopping. There's a name for excessive cell growth past these points: Cancer. Breast size in particular is controlled by DNA, fat levels and hormones, one we can't control, one that fluctuates constantly, and one that has nasty, unavoidable side effects if you mess with willy nilly.",
"If we knew how to start and stop cell growth, we wouldn’t be inundated by cancer like we are.",
"Your body and everything it does is because of DNA, which is like the lines of code in a computer's operating system that tells it how to behave, but instead of using 1's and 0's, it uses four different chromosomes, G, C, A, and D. Long lines of this coding are called a genome, and they are incredibly delicate and complicated, and our bodies don't contain all the information within its genome to do that. Imagine a computer virus that deletes your files. You can run antivirus software to find and it and uninstall it, but you won't be able to get your files back, because the coding you would need to do that is very complicated and we haven't figured out how to do that yet."
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m98b03 | How do touch sensitive lamps work? | I looked it up and it has something to do with capacity but to be honest I didn’t understand any of the explanations I found. | Technology | explainlikeimfive | {
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"There is a common electronic component is called a capacitor, and we use them because they are able to store a little bit of energy, and release it in a way that we understand very well. We can design a circuit with a capacitor that causes electricity to 'oscillate'. This means that it goes back and forth thousands of times a second, with the frequency of this being controlled by the size of the capacitor. We put part of this circuit just under the bit of the lamp that you are meant to touch. The reason that this is useful is that our bodies can actually act like a capacitor. This means that when you touch the lamp, you change the frequency that the circuit oscillates at. It's very easy to feed this into another circuit that can see when the frequency changes, and change the state of the lamp (on/off, or brightness). Touchscreens on phones use basically the exact same concept of your body's capacitance, which is why a water droplet can make your phone think it's been touched, as a water drop also has some capacitance.",
"Your skin conducts electricity. When you touch the lamp, it detects a change in voltage and uses that as a trigger to change the setting of the lamp.",
"Water is a \"polar\" molecule. That means it is slightly positive at one end and slightly negative at the other end. If you put it in an electric field, it will try to rotate. This stores a little bit of energy in the molecule. We call the ability to store electrical energy in this type of way \"capacitance\". And humans are mostly made of water! Put your finger in an electric field and the water molecules in it will try to move. A sensitive circuit can detect this *change* in capacitance and then react. That's how touch sensitive switches and most touch-screens work."
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m99z20 | Why didn't we keep the fur while evolving? | Biology | explainlikeimfive | {
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"A widely accepted theory is that, when human ancestors moved from the cool shady forests into the savannah, they developed a new method of thermoregulation. Losing all that fur made it possible for hominins to hunt during the day in the hot grasslands without overheating."
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m9a19y | Why water feels soft in some houses and hard in others? Is it minerals? | Some places the water just feels so soft during a shower or when washing your hands. Other places, especially old buildings the water can feel a lot less comfy when washing your hands etc. Why is this? | Chemistry | explainlikeimfive | {
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"text": [
"You have it about right! \"Soft\" is the correct word. Some (like newer) buildings have a \"[Water Softener]( URL_0 )\" which removes minerals from the water, making it feel less \"rough.\"",
"Along with mineral content having different feels, it can also be the type of aerator or sprayer. Adding air bubbles to the water make it \"softer\" and better at \"wetting\" surfaces than a solid stream of just water (which has a single surface tension rather than one subdivided/perforated/weakened by air). Also air bubbles added to water underneath a floating object such as a boat, will cause the item to sink quite rapidly. Structural integrity of the surface tension is destroyed by subdivision (aside from air compresses and water doesn't, so bubbly water is \"extra squishy\" and can't carry loads).",
"Yup. It's minerals. Hard water is water that's come from a limestone reservoir underground. It contains a lot of Calcium and Magnesium ions, dissolved from the limestone."
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m9a1gj | What makes our brain determine whether something is hygienic or not? | On a scientific level, what makes something hygienic? What goes through our brains to lead us to a conclusion? | Other | explainlikeimfive | {
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"The answer is complicated, and a lot hinges on what you are conditioned to feel. I recommend a book called \"The anatomy of disgust\", by William Ian Miller, where these issues are investigated."
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m9a3gx | Why does your brain seem to make you want to scratch things that would heal faster when left alone? (I.e. bites, rashes) | Biology | explainlikeimfive | {
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"Simply put, the brain does not know that it will heal faster if left alone. In most cases, when your body has something stuck to the skin, itchiness can get the conscious brain to do something about it by scratching it away and letting the body start healing; but when that something is, say, a scab, the system works against itself. The situation is similar for bites and rashes; the body sends an itchiness response to make sure there is nothing on the surface of the skin that will keep causing it while the immune system deals with what's already made it into the body, but the cause of the issue is no longer directly on the skin, so the brain just made the problem worse by asking the body to keep messing with the thing its trying to heal.",
"Foreign substances trigger the body’s immune system. The body’s immune system releases histamine, a compound that helps white blood cells get to the affected area. Histamine is what causes the itchiness, inflammation, and swelling. Bites and rashes itch because histamine sends a signal to the nerves around the affected area. You are feeling the body’s response to fighting the foreign substance."
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m9algh | Why do MRI machines cost so much to shut off? | Other | explainlikeimfive | {
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"You need liquid helium cooling to keep the magnets working. The only way to shut the MRI machine off is to flush the helium. And then you need to pump in new helium to be able to start it again. That's not particularly cheap.",
"In addition to the helium issue, there is also the expense of re-calibrating it which requires some very special nerds and is a fairly extensive process.",
"So basically the magnetic field from the MRI comes from a huge current in the superconducting wires inside a liquid helium bath. The superconducting wires are special in that below a certain temperature, they can flow the current without resistance. Normally, because the current is so large, you want to slowly put it in or take it out, because if you do it too fast, it's too \"turbulent\" for the current to flow without resistance. This heats up the wires and causes a runaway effect, which will boil off the liquid helium. In an emergency, you can't do it slowly, so a lot of the liquid helium is blown off. For regular maintenance, you can take the current out slowly and the liquid helium is not wasted. Normally, you can collect the helium flowing out and recycle it, but in an emergency, a lot of liquid is turned into gas and takes up a lot of room, so the pumps can't collect all of it and most of the gas is relieved to atmosphere. By the way, just to give an idea of the cost of helium. I work in lab settings not hospital so maybe the prices are slightly off. But 100L liquid helium costs about $1500 plus shipping and handling. Typical MRI machines holds 1700L liquid helium. So each emergency quench will cost $25K in just liquid helium, plus shipping and machine maintenance."
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m9apbf | Why do some fruits ripen after picking, but others don’t? | I eat avocados and grapes every day, and I noticed that I am able to perfectly ripen avocados, but my grapes just stay the same and then rot. I cannot figure out why I cannot turn a sour grape into a sweet grape like I can turn a hard avocado into a perfect one. Thanks. | Biology | explainlikeimfive | {
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"Kind of hard to get into the details as an ELI5, but simply some plants ripen on the plant and some dont. It comes down to the production of ethylene gas in something called the climateric stage of ripening. Avocados will continue to produce this gas when plucked, which triggers avocado cells to continue respiration at a higher rate, which makes them continue ripening (also why closing them in a bag helps speed that up). Grapes on the other hand, are preclimateric. Once you pluck them they will not produce ethylene, and not have this faster ripening effect (for the most part. Grapes and melons have exceptions to this rule)"
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m9bbcn | Why do we need to stretch our muscles after doing any form of physical activity or exercise? | Biology | explainlikeimfive | {
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"text": [
"**The long answer:** When you damage sarcomeres during use, the body reacts by making new ones to compensate. Think of it as scar tissue within your muscles. When created the actin filaments within doesn't always line up 100% with the direction of all the other actin filaments in the sarcomere. The more a filament is off the ideal angle , the more ATP is wasted due to the actin/myosin causing a more or less diagonal pull instead of pulling straight along the axis of the surrounding muscle fibers. You know, basic classical mechanics. Vectors and shit. These conflicting directions in your muscle fibers are undesirable when you want the muscle to be as efficient of as possible. So we stretch the sarcomeres to make the actin filaments slide so far along each other, that they reach the end of their counterpart. Let's call it elasticity. This pulls the misaligned filaments more into the axis along which the majority of the other actin filaments lie, because when the elasticity is gone deformation begins. Better aligned muscle fibers equals better efficiency. & #x200B; **The short answer:** Gains, bro!"
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m9dacw | How do full blooded siblings end up with such varying results from DNA testing? | Biology | explainlikeimfive | {
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"text": [
"A child will inherit 50% of each parent's DNA. 50% of the mother, 50% of the father. But each child will not receive the *same* 50% from each parent. The genetic code that is passed on is random, every time. So, let's say one parent has a small amount of African ancestry in their blood. They have a child, which inherits 50% of their genetic code at random. That small percentage of African ancestry is passed on to them by chance. But when that parent has another child, the 50% they inherit is different to their sibling, so it's entirely possible that they don't inherit any of the trace amounts of African genetics at all. This is how two siblings can produce different genetic ancestry results."
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m9dcmq | how do fireworks form those cool shapes? | Technology | explainlikeimfive | {
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"text": [
"The add various shaped charges into the firework to achieve different effects, different chemicals burn brighter and in different spectrum than others so will have different colours and intensities. Longer fuses and packaging create delays for the explosions.",
"The fireworks designers know the physics and the chemistry and use that info to build fireworks that will explode in certain patterns(physics) and give off certain colors (chemistry) [ URL_0 ]( URL_0 )."
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m9drt2 | how we don't bite our tongues more than we normally do. | Biology | explainlikeimfive | {
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"Our brain is trained to not just like we are trained to eliminate your nose out of your peripheral vision until it’s brought to our attention. Usually when We bite our tongue it’s because we have more brain power going to another function such as chewing gum and being in your phone or on the computer. Or you are Really hungry and are focused on scarfing down food. You’re taking power from one engine and adding it to another for the time being so to speak"
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m9dyad | What exactly is a memory, physically? | Is it a series of chemicals one creates overtime and stores in the brain? What exactly is being stored in your brain once you make a memory? | Biology | explainlikeimfive | {
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"Physically, a memory is a specific pattern of neurons firing in the brain. Recalling that memory means making those neurons fire in the same pattern again, essentially reconstructing the memory.",
"Memories are stored as links between neurons in your brain. Neurons are brain cells that send signals to other neurons. The number of neurons in your brain mostly stays the same over your life. But, the links between them is what changes when we learn or remember things. The exact nature of how a memory gets encoded into links between neurons isn't well understood though.",
"No it's not the chemicals themselves but the neuron network which is the links formed between different brain nerve cells which are connected to all the surrounding neurons by synapses. The neuron network is electrochemical in nature. It's not only the precise chemicals but the exact flow of electrons between them. It's not an easy concept to grasp but if you think of how data is stored in a book or on a hard drive - nope it's the exact opposite of that. It's not orderly. Think about a network of telephone poles. If you have 10 poles (neurons) in a circle around each other - you take each pole and run telephone cables (synapses) from that pole to every other pole. So you have 9+8+7+6+5+4+3+2+1 = 45 connections. Add another pole and form another 10 connections and keep going up to a million poles. Now you'll have n (n+1)÷2 = 500,000,500,000. 500 Trillion connections! A memory will be stored in a group of connections built up from individual synaptic connections. Now comes what will blow your mind - These aren't permanent. When you recall a memory you are overwriting the connections that are there. Those childhood memories of yours aren't childhood memories - they're memories of you remembering memories of you remembering memories of you remembering memories of what your brain reprocessed during your sleep from your short term memories on the day. Don't believe me - check this out: [Professor Bruce Hood - Change Blindness]( URL_0 ) This is explanation very, very ELI5 and there's a lot more to this.",
"Nobody knows yes because in experiments where doctors cut different pieces from the brain the patient don't lose his memories. And hence the theory of the fractal brain."
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m9g3zh | What's happening when a displeasing sound causes us to squirm? | Biology | explainlikeimfive | {
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"Humans, when sensing unpleasant things like sounds or sights or emotions, have a lot of coping mechanisms to try and force the brain to focus on something else by overwhelming the senses. When someone is embarrassed, or frustrated, or scared, or seeing or hearing something that is overwhelming them emotionally, they will often rub their head or hold their face or bounce around or making random noises. These are all an attempt to overwhelm the brain with nonsense information to try and overpower the unpleasant sensory information, hoping that it will become less noticeable or \"lost in the noise\", so to speak.",
"Certain tones and sounds (such as nails on a chalkboard) are highly displeasing to us because the sound frequency is the similar to a high-pitch shrill scream, such as made by a creature in great distress. You squirm because your body instinctively wants to respond to this as a scream and react in some form."
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m9g4q1 | When we clear our throats, what is actually happening inside of them other than us making noise? | Biology | explainlikeimfive | {
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"text": [
"Something has gotten into your throat from somewhere. No matter how small, it is causing enough irritation that your brain makes you vibrate your voicebox to try to dislodge it and either cough it up or swallow it.",
"Not a Pedagogist but did vocal performance, how it was explained to us is that when you clear your voice you're causing your vocal cords to smack and rub violently against each other in a way that shakes things loose in your throat."
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m9g858 | Why is it impossible to transplant a bladder? It seems strange to me that a heart can be transplanted and a bladder can't. | Biology | explainlikeimfive | {
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"It's not impossible, it's a weighting of the positives and negatives of a procedure. Transplantation is drastic, dangerous, and life altering. The patient will have to take drugs that suppress their immune system for the rest of their life along with the many side effects that patients will now have to live with. So we generally only do it for stuff that's either not prone to rejection that the patient won't have to spend a lifetime on anti-rejection drugs (i.e. cornea) or for stuff where if the patient doesn't have it they will die. A heart? You can't live without it. So transplanting easily edges out the risks and possible complications. A bladder? Not so much. Surgeons are good at fashioning bladders from bowel or small intestine, they can create urine accumulation pockets to be drained by cathater, they can route the ureters to a port on the body to be collected by a bag. These are a mere minor inconvenience compared to a lifetime on anti-rejection drugs and a weakened immune system.",
"I haven't found any sources saying it's impossible. There are other ways doctors have been able to form new \"bladders\" using the patient's bowels or insert new ones that aren't purely biological. It's probably better for the patient too because a bladder transplant would cause them to get on immunosuppressive drugs to prevent organ rejection.",
"It also has to do with the neurologic control of the bladder. From a neurologic point of view it's not easy to control your bladder then decide to take a piss. It actually requires exquisite control and coordination by your nervous system. Almost all of this is happening at an unconscious level, just like digesting your food is a complex, coordinated activity that you don't have to think about. You can't hook up the transplant recipient's bladder to the nervous systemic a functional way, so the new bladder wouldn't work like you would hope it would.",
"The most common types of infection in otherwise health adults are bladder infections. We don't transplant bladders BC it is already prone to infection, the surgery will increase infection risk (kinking of ureters/scar tissue) and then we are going to give immunosuppressive drugs which will increase the risk of infection even more! Plus the drugs have side effects that lower kidney function, diabetes, on top of immune suppression. This is why we make bladder conduits from small bowel. No immunosuppressive drugs, still gets complicated by infection occasionally.",
"Neobladder reconstruction using part of one's own ileum (terminal past of small bowel) is the answer. No need for lifelong immunosuppressants and complications (inclued higher risk of dying from COVID) associated with these.",
"The body have a very strong immune system which is designed to detect and destroy any foreign biological matter. That unfortunately includes functioning organs from other people. So transplant patients have to take medication for the rest of their lives to suppress their immune system which does leave them more open to infections and might even get complications from the medication themselves. So doctors will try to avoid doing transplants if they are not needed. In the case of the bladder it is a very simple organ that you can do without or with simple man made versions. So even in the rare cases where the bladder have to be removed the doctors will not transplant inn a bladder from someone else as the complications from a transplant is worse then the complications from having the bladder removed entirely. And depending on the exact reason for why the bladder had to be removed they can even just put in a plastic bladder instead as it will not be attacked by the immune system.",
"Neobladder reconstruction using part of your ileum. Avoids all the usual transplant issues. BUT always advise patients and their family of the risk of electrolyte and even metabolic imbalances. URL_0 Metabolic acidosis leading to hyperkalemia is not uncommon, especially in those who have conditions making them already slightly acidic (ie all diabetics and kidney patients)."
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m9giaa | What value do wasps have, besides being annoying and painful? | Biology | explainlikeimfive | {
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"They are both scavengers and hunters, they clean up dead things, and hunt things like mosquitos and other small bugs.",
"Evolution does not create creatures because they have a specific value to the nature but rather because there was room for it to develop. There are actual suggestions to eradicate the mosquito as they do not provide any value to anyone and does more harm then good. But wasps do provide some value. They do compete with bees but they do also thrive in areas where there are few bees. Their aggressiveness is part of this as they can thrive with animals that frequently raid bee hives for honey. Wasps do also have an easier time consuming fallen fruits and other dead materials as they have stronger jaws then bees. So there are quite a few areas that would be very different if it were not for the wasps.",
"Many wasps, just like bees, are very important pollinators. URL_0 In fact, fig trees are primarily pollinated by a [family]( URL_1 ) of wasps.",
"There are a *lot* of different wasps. That's kind of like asking \"what value do birds have\", there is no one correct answer. Some pollinate, some hunt, some scavenge. Figs wouldn't exist without fig wasps, some wasps like hornets are very important predators of pests like caterpillars who could otherwise devastate many tree or crop species, etc. Edit: there are tens of thousands of described species of wasps, so there are literally tens of thousands of different answers to this question.",
"In Mexico there is a wasp that preys on tarantulas, so it helps keep that population in check",
"Wasps tend to be a bit more aggressive when they attack than bees. First off? They tend to bite more, which is already problematic enough, but more importantly, their stingers aren’t barbed. When a bee stings you, it has a barb on it so the stinger is more likely to dig deep and stay stuck there, where it will then steadily load the would be attacker with venom while the bee flies off and dies. A wasp, however, doesn’t have this barb, so it instead can - and will - sting you multiple times to get the venom inside you and the message across. This can make them seem more generally aggressive because to us humans, allergies aside, a single bee sting can usually seem a tad more manageable than say, 15 or more wasp stings because one is localized on a single area, while the other could be all over your body. Wasps also tend to be bigger than bees and therefore have more of an intimidating presence than their bee cousins. That said I typically find Wasps to be just as docile as long as I’m not too close to their nest- No. Wait. Important side note before I close this out. Wasps, especially paper wasps, tend to build nests where there is more useable material, which tends to be where there is undisturbed wood or pulp. Most flower seeking bees won’t build a nest in your shed ( though some do, and the less disturbed the better because hey, it’s safe from almost all predators that aren’t other bugs and eventually, humans ) but wasps see that softer, rotting wood and literally eat it right up to build a home right in your home. Which is arguably the only worse place they could build a nest aside from right under your feet, which they also can do. So wasps are also considered more problematic due to their location too. If you see a bee flying around in your hone, you usually think it flew in, and might stay away from trees and carefully check the brickwork for a rogue nest. You see a wasp and you can’t be so sure that it’s not literally living in some weird nook or in your wall. Okay but that aside, I don’t mind wasps too much because territory aside, a lot of them aren’t much more aggressive than bees normally. They will definitely drink water right out of a cup you offer them, if it’s a warm summer day. They’ll stand right on your finger and literally drink the water right off of it if you wanna be bold. Just try not to flinch and startle it because that up close and personal, it will bite if startled, but like many other insects, if you can afford to just leave it alone, you’re fine. See it inside your house, and that’s a problem. In the wild? Nah. Just watch where you step and stick to the pathways so you don’t step in a foot full of wasp nest. Also if you do see a wasp nest outside while shopping, try and let the property owner ( or a nearby store manager ) know so they can get it removed and or relocated without potentially harming any children, pets, etc in your area.",
"There are a lot of different species of wasp and people are generally only aware of a few of the big species that haunt trash cans and picnics. Many species of wasps are highly valued as predators of pests by farmers and gardeners.",
"Some wasps lay eggs in the larvae inside the burrowed nests of various tree borer insects with their lengthy ovipositor, and don't tend to bite humans although they are some of the largest (therefore scariest) wasps. So one of the jobs they do is keep tree-killing parasitic insect population down. But that's only a subsection of all wasps. But the most effective job most wasps or yellowjackets do, is keep me from digging around in old woodpiles and wondering what that hole in the ground is... most of them nest in such conditions."
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m9gse4 | How do dryer door switches become broken? Is it an internal problem only or can it be from slamming the door shut too hard too often? | Other | explainlikeimfive | {
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"text": [
"Moving parts wear out. It's a consumer product so they're not gonna spend for top-of-the-line, insanely-durable switches, because they're trying to compete on price for people like you and me who don't want the price to go up by $20 just to slap in a high quality switch."
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m9gtxn | Why is the Mafia or the 'mob' not as prevalent and talked about today as it was in back in the day? | Other | explainlikeimfive | {
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"Because entire crime organizations started being charged under the Racketeer Influenced and Corrupt Organizations (RICO) act, passed in 1979. Instead of just charging lower level criminals, RICO allowed cases to be built in a way that deconstructed the crime families or weakened them severely.",
"They are still talked about in the areas where they are active. You don't hear about them constantly because they are more careful about getting caught or even making their presence know. It's not as easy to get away with crime nowadays. With the cameras everywhere, fingerprinting, and high tech security systems.",
"Organized crime was propelled to prominence by Prohibition, that well-intended disaster of banning alcoholic beverages in the US. The Mob was the most prominent type of organized crime, so they got the bulk of the boost. After prohibition, the Government needed something for all those agents to enforce, and moved to recreational drugs. The Mob followed, to a degree, but also returned to their legacy businesses of prostitution, gambling, and loan-sharking. At the low end of the recreational drug trade new players, the criminal gang and the foreign drug cartel, got into the picture. Over time, gambling and prostitution drifted away from facilities-focused activities that the Mob could manage into more worker-entrepreneurial settings or outright legalization. It's hard for a mobster to run a call-girl with a webpage or compete with a legal poker parlor. The increasingly violent drug gangs were not a scene that a civilized mobster would want to engage with, so the mob was pushed into a smaller part of the \"organized crime\" space. There are still plenty of organized criminals, but more of them are gangbangers and fewer of them are mobsters."
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m9iepf | What are the limitations to inductive charging? Why can’t we charge mobile computers or even electric vehicles like this? | Physics | explainlikeimfive | {
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"We can it's just more expensive for the electronics needed for high power switching, and very sensitive to alignment and distance. And if you put a piece of metal in the way you get an inductive heater instead of a charger which makes it harder to build around. That and they are a bit inefficient especially when misaligned. Inefficiency at high power means a waste of power for one, but also potentially kilowatts of heat being generated somewhere. Though there are different research projects working on the alignment problem. Like overall inductive charging is -less- convenient than wired charging, and more expensive. If you have something that needs sealed it makes sense, but for phones and laptops it's more of a gimmick. Like sure you can just place your phone on a charging pad, wich may make sense in a car phone dock but what do you do if you want to still use your phone while it's charging? So we're getting closer, but it's just not quite at the point where it's useful enough and cheap enough to be widely supported and standard enough that having a wireless charging dock in your car will be as common as having usb ports are nowdays."
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m9ifwt | Do woodpeckers get brain damage or concussions from pecking wood too much, if no how is it possible? | Biology | explainlikeimfive | {
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"text": [
"Their tongues wrap around their brains to cushion the blow. [I'm not shitting you. It's true]( URL_0 ) 1000G's on impact. Imagine that.",
"Woodpecker brains do have a buildup of a protein that is associated with brain damage in humans. This may actually provide some stability and protection to the axons it wraps around. URL_0 .",
"Smaller brains. Thicker skulls. More cerebrospinal fluid. Really it’s the human brain that’s special, in that it is especially huge and fragile. It needs the skull to support it and can’t stand up under its own weight. You can freeze and defrost small mammals like guinea pigs and rats but cryofreezing a human brain would cause it to just fall apart."
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m9iid9 | How does dementia and other similar mental illnesses make people forget things? | Biology | explainlikeimfive | {
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"They literally damage and kill off sections of the brain. As sections degrade, functionality is lost. Depending on how far along, it could be memories, language, motor skills, or breathing itself.",
"EDIT AND REMOVED: Sorry, this was an explanation for MS, which doesn't include dementia. I sorry.",
"Witn vascular dementia blood vessels wither and slowly starve off sections of the brain. The resulting death is from the autonomic system (which is the deepest part of the brain responsible for breathing, heartbeat etc) which is finally starved of oxygen and shuts down. While areas of the brain are slowly killed off from the lack of blood throughout the disease you lose the corresponding function. As higher thinking and memory is towards the outer edge they are the first to be effected, the inner (animal) brain is deepest and responsible for movement and staying alive and tends to be the last part to effected, which is why you end up with an unfortunately aggressive shadow of the person left that cannot form new memories or think for themselves."
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m9j19b | What can F1 Driver do to “push” when the team told them to do so during a race? | I am currently watching the newest season of F1 documentary on Netflix and I noticed that teams keep telling their drivers to “push”. So, what can the drivers do to actually “push”? | Other | explainlikeimfive | {
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"There needs to be a certain conservatism when driving to not wear the tyres too much, not use up too much of the carefully calculated fuel amount, not wear out the brake disks by overheating them, and similar things. It's not just a matter of going as fast as possible all the time. If the team think that they have something in hand, or need to open up a little more gap to make time for a pit stop they can tell the driver to be a bit more aggressive braking, corner harder or turn on a different engine software mode that gets better acceleration at the cost of extra fuel.",
"As much as we like to think, F1 drivers (indeed, most race drivers) aren't at 100% all the time, as they need to look after their tires, their fuel, their engines etc. So, when a driver's engineer tells them to push, that essentially means \"There is no longer any need to look after things at this point in time, go 100%\". What that generally entails for the driver is things like braking later & not coasting, into corners, accelerating earlier out of them & turning more aggressively through them",
"They basically pick up the pace as much as they can. They aren't always pushing 100% as pushing too hard will cook the tires and make them wear too quickly or they'll use too much fuel. So they can push the car a little harder to gain time/create a gap from the cars behind when needed.",
"A racing driver doesn't go flat-out all the time - they're mostly about 95%. For the bulk of the race, they are managing the equipment - taking care of the tyres and fuel consumption. When the team tells them to push, they're telling the driver to disregard that and \"push\" the limits. Driving as close to 100% as they can to improve their standing in the race. In the case of F1, that's usually trying to engineer a better track position to make their pit strategy work."
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m9jfsx | What makes magnetic metals magnetic? | Physics | explainlikeimfive | {
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"The metals have a load of things called electrons in them. Electrons (and some other stuff) have a property called \"spin,\" which is one of those weird quantum mechanics things. Spin isn't a kind of movement, but (mathematically) acts a lot like spinning. One of the ways it acts like actual spinning is that it causes a tiny magnetic field (due to it being like an accelerating or moving charge). An electron can have two different kinds of spin, sometimes called \"up\" and \"down\" or \"1/2\" and \"-1/2\", which if spin was like actual spinning would correspond to the two directions something can spin (clockwise or anticlockwise) - but because it isn't spinning, don't. Which direction the tiny magnetic field goes depends on the spin. And normally electrons will pair up, with one of each spin, and their magnetic fields will cancel out (at large enough distances away). But in some metals the electrons are arranged in specific patterns, where their spins interact and sort of \"line up\", and so their magnetic fields add together, creating a large scale magnetic field. Some metals form these arrangements naturally and are fixed (\"hard\" magnets), and in some metals you can force the electrons to line up by putting the metal in a strong magnetic field, but then you can also knock them out of alignment (\"soft\" magnets)."
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m9jv5c | How do magic erasers work? | Chemistry | explainlikeimfive | {
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"text": [
"Magic erasers are melamine foam. Basically, plastic with lots of tiny bubbles. As you scrub with the eraser bits of the foam will come off, leaving very tiny, sharp edges of the bubbles. These edges can get into the tiny nooks and crannies in a surface and scrape off whatever is on that surface."
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m9k7uu | Why is a rapid heartbeat and high blood pressure from exercise healthy for your cardio system, but the same effects from drugs like alcohol and nicotine cause damage? | Biology | explainlikeimfive | {
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"PSA: I'm not a doctor - I got my degree biomechanical engineering - so please don't take this as medical advice. If your heart is beating really hard for a really long time, just like any muscle it's going to get tired and need rest, it's just better at recovery than other muscles in your body. If you get a leg cramp, you stop running and limp for a bit - what happens if you get a heart cramp? You die if it's bad enough. If your blood vessels have lots of pressure for a really long time, they'll spring leaks - just like a sprinkler system - if you have too much pressure in the system for too long you'll spring leaks. Sprinkler leaks? Long weekend or pay someone to fix it. Blood vessels leak? You die if it's bad enough. In both cases if you repair the damage or let things rest, they can recover and be used just fine - but if they're under this stress for too long they can't recover and repair. Your body does this automatically - when you're not running, your body is making sure everything is getting repaired and is in a good state. Things that keep your blood pressure high for too long or your heart rate high for too long won't give your body enough time to do that. Remember Chris Farley? He had a heart attack after 17 hours of cocaine and hookers. He had a heart cramp and died - the activities and drugs kept his body going too hard for it to rest, so it gave out. That's what makes some drugs dangerous, and that's why doctors want to help keep both in a normal range. Normal just means that your body should be able to maintain things in between those high moments.",
"Exercise is under your control, you can feel when it's getting too much, and you slow down or stop, you rest after. Your body enjoys it like a luxurious stretch, there is feedback and growth, and the muscles get stronger. When you use drugs, they artificially stress your heart and cardiovascular system. It's like putting yourself into a machine to exercise.\"A thousand push-ups? Sure!\" Drugs screw with the knobs, you can't control it, you can't slow down when it hurts, you can't stop, you can't shut it off to rest. There is no useful feedback, so it's just damage without growth.",
"These are side effects that can point to different diseases. If you're out of breathe because you just ran really fast, you know that it's because you ran fast. If you're sitting around doing nothing at all and the same thing happens, you can't be sure why, but it could mean that doing regular things like sitting down or walking to another room are now taking just as much effort as it would take to run down the block really fast. And you don't run really fast all day, so your body has time to recover. If it always takes that much effort to do anything, your body never has time to recover and starts to wear down much faster than it would otherwise.",
"Alcohol damages your liver, and you get high blood pressure because has [A LOT of blood pass through]( URL_0 ) it to be processed, and if it's damaged there's basically back-pressure that increases your overall blood pressure. Lungs also have major blood vessels going through them, and smoking decreases the efficiency of your red blood cells transferring oxygen and carbon dioxide as you breathe, so your body detects the lower levels of oxygen and makes your heart pump faster, to get more oxygen going to the cells in your body. Different causes, but basically both are abnormal (not usual) instances of high blood pressure, and more importantly they're chronic (long term, not just a few minutes after you've exercised), so they cause strain / damage to the heart too."
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m9kbet | Why is saltwater marine life usually so much more colorful and vibrant? | Biology | explainlikeimfive | {
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"If you’re talking about aquarium fish, it isn’t because they’re saltwater. Plenty of saltwater fish are boring. It’s because they’re tropical. Animals throughout the tropics are more colorful and if you were going through the trouble of having a saltwater tank (which is very difficult to take care of), then you might as well select the most colorful and interesting looking ones. And in the ocean, there are way more to choose from. People think the reason tropical animals are more colorful is that given the biodiversity and density it’s more important for species to find each other for mating than to avoid predators.",
"While I haven't researched it, my best guess would be habitat. In freshwater environments the watch is much more muddy and shallow and the best places to hide are rock formations. That would explain why larger predatory fish sometimes have splashes of color while smaller ones don't. Ocean fish mainly inhabit coral reefs so they have evolved to be much more vibrant. Also in the ocean there are many more venomous fish that are brightly colored to ward of predators. Along with this, the fish that inhabit open water, such as bluefin tuna, are shades of blue to blend in with the open water around them. This isn't to say that all ocean fish are bright and colorful, take the stone fish for example. They are sandy browns and greys that blend in with the sea floor because they are ambush predators. Another senerio is deep sea fish, which are often darker colored as color doesn't matter when you can't see. I hope that helped and I hope I'm not spewing false information, remember I didn't fact check any of this and am just making an educated guess.",
"Most fish aren't really. You're specifically thinking of coral reef fish. Most fish, saltwater fish included, are just muted browns, greys, and silvers. Reefs are a very unique and colorful environment and some of the most densely populated habitats in the sea. The leading theory is that reef fish are so colorful to help differentiate in such a crowded environment. There are so many different fish species going every which way on a reef that the colors and patterns help them recognize rivals and potential mates of their own species. Many colorful reef fish actually change color at night. Their colors fade, their patterns become blotchy. This helps them hide at night while they sleep, tucked away in nooks and crannies in the reef while the nighttime predators roam."
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m9ky3p | Short term memory loss | I’m asking this question because i was so confused because if you lose that memory wouldn’t you also have long term memory loss because the memory is lost. | Biology | explainlikeimfive | {
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"Memories are stored as connections between neurons in different parts of the brain. Short term, working memories are stored mostly in the pre-frontal cortex. Explicit memories are stored in other parts of the brain and things like muscle memory are in the cerebellum. So if something damages the prefrontal cortex, you might lose the ability to store short term memory, but it doesn’t affect the existing memories stored elsewhere."
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m9l483 | What is strange matter, and how do we know about it? | Obviously we haven’t gone and studied it physically, but I’m not sure how we even know it exists. Is is all theoretical? | Physics | explainlikeimfive | {
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"It's a hypothetical form of matter made from a stable form of Strange Quarks. We don't know if it exists or not, it's just that our current model of particle physics predicts it might exist, but our current model of particle physics is infamously incomplete so it might not exist. If it does exist, it only exists in the cores of Neutron Stars and would only be accessible to us when two of them explode and spill their guts everywhere, and even then, only if the idea that Strange Matter is stable outside high pressure environments is true. If it isn't, we'd never know unless we made a device that could sample a Neutron Star or if we can make it in a Particle Accelerator. Note that currently, evidence points to Strange Matter either not existing or not being stable outside high pressure environments because the most famous predicted property of Strange Matter is it turns anything it touches into Strange Matter, and because Neutron Star collisions are a thing and not that rare, you'd expect a piece of Strange Matter, no matter how small, to reach Earth and turn it into a Strange Matter goup ball unless it doesn't exist. can't exist outside of Neutron Stars, or is mind boggingly rare.",
"Within the standard model (our current idea about the smallest kinds of stuff that makes up the universe), there are 6 particles called quarks that make up lots of other stuff. These come in pairs. The most common ones are the up and down quarks, which make up protons and neutrons, which make up the main body of atoms, which make up basically everything we care about day to day. There are also top and bottom quarks. The final pair are called strange and charm. Stuff made from the strange quark is called strange matter. Like with a lot of this sort of teeny-weeny particle physics, what we know is a mix of theory based on models and observations from experiments. The theory relies on lots of complicated maths. The experiments basically involve smashing tiny things together with a *lot* of energy, and seeing what even tinier things fly out. But it's really complicated. Like, imagine you wanted to know how a pocket watch worked, but you didn't have a screwdriver small enough. So, you just took two pocket watches and threw them at each other until they broke. Then, you looked at the springs and cogs that fell out and tried to put them back together."
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m9ll22 | how do we fall asleep? what happens in the brain? | Biology | explainlikeimfive | {
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"Your brain has a lot of collections of specific kinds of neurons that regulate this. One set of them, that are active right now if you're reading this, promote arousal. But another set of them eventually inhibits the system that promotes arousal, causing you to no longer be awake."
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m9m9mk | Why does the Earth rotate about its own axis? | Earth Science | explainlikeimfive | {
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"Ultimately, the Earth got its rotational momentum from the movement of the giant gas cloud as it collapsed to form the solar nebula. Debris which formed in the nebula may well have imparted momentum to the Earth, but such rocks and planetesimals all had their respective momentums from the collapse of the gas cloud too. Usually collapse from a ginormous, diffusive gas cloud is centred around two points (binary systems are more common, probably some complicated maths reason why), in our case it seems to have been just one point which eventually became our Sun. As things collapse and start to rotate around the clump(s) of mass, rotation inevitably occurs due to conservation of angular momentum. Any tiny bit of relative movement is amplified exponentially when matter is being concentrated from a diffuse cloud that’s light years across into a solar system — like the way an ice skater’s spin speeds up as they pull their limbs closer into them."
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m9mg56 | Why do brains like to scare themselves, by making themselves believe they are being followed or something? | Other | explainlikeimfive | {
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"It's not so much that your brain likes to do those things. Your brain is just designed to keep you alive because the cautious suspicious brained animals that we evolved from lived. The ones who weren't suspicious of that big scary predator chasing them didn't survive to pass on their genetics."
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m9myzd | Wavelength corresponds to colour, but how? | Between the input (wavelength) and output (colour), what occurs? How do we receive 650nm, for example, and interpret it as red? What even is red? What is colour, really? | Physics | explainlikeimfive | {
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"Out eyes have four types of light-sensing cell, the fourth of which is not important for this question. The other three detect a range of frequencies, which normally correspond to a set range of frequencies which we lump together as 'red, green, and blue'. A red object's light is mainly absorbed by the 'red' cells, and so on. Our brain interprets the signals from these cells to produce color. Therefore, color is an experience like taste, while frequency range is an objective and measurable fact.",
"Color is surprisingly complicated! There are a few related, but separate, ideas you could call 'color': - Wavelengths of light: The distribution of different frequencies of light entering your eye. This is a complicated distribution that has more data than your color vision can perceive. For example, you might have one level of brightness at 682 nm, another at 573 nm, another at 562, another at 478, another at 426, and so on. This is called the \"spectral power distribution\". - Color *vision*: The amount that cone cells in your eye are stimulated. If you have normal color vision, you have three types of cone cell in your eye. One responds strongly to short-wavelength blue light, one to medium-wavelength green, and one to medium-long wavelength greenish-yellow, with their sensitivity falling off quickly to either side. \"Red\", in this model, means \"stimulates the greenish-yellow-sensitive cones a moderate amount and mostly doesn't stimulate the green or blue-sensitive cones\". This layer takes the distribution of frequencies entering your eye and boils them down into three numbers describing how much each cone type is stimulated, called the \"tristimulus values\". Interestingly, some combinations of stimulus can't be achieved by any mix of actual light frequencies, meaning that there is a \"greener green\" than any green you've ever seen that you're physically capable of perceiving but could never actually see. (Users of psychedelic drugs often report seeing such 'impossible colors'). - Color *perception*: Your perception, as a thinking thing, of what objects are 'the same color' as what other objects. This takes the previous layer and runs it through some really complicated filtering that accounts for things like ambient light. Optical illusions take advantage of that filtering - see, for example, the [checker shadow illusion]( URL_0 ). Under normal circumstances, though, those corrections help you recognize that a white wall illuminated by yellow light is \"really\" white (even though your eyes are receiving yellow light). - Color *of a material*: The properties of a material cause it to emit or reflect certain wavelengths more or less than others. If an object reflects a lot of short-wavelength (\"blue\") light but not other colors, we say that the object \"is blue\". The color of an object is the color you perceive when the object is illuminated by white light without any surrounding context.",
"Color is just how your eyes react to a particular wavelength. For most people, the reaction to a particular wavelength is the same, so we all agree that wavelength correspond to a certain color (ex. red), just like if scientists measure a wavelength of 1cm, we all agree that this is a microwave. People who are colorblind has a different response in their eye so they can't agree with the rest of us on that color. Another analogy would be that for most people, getting pinched (input) is a \"painful\" sensation (response), getting tickled (input) is a \"funny\" sensation (response). For certain people who can't feel pain, they have a hard time relating.",
"Inside your eyes are special cells called cones that detected light and can distinguish between colors. There are three types of cones and each is sensitive to a different wavelength of color. You can see a graph of the sensitivities [here]( URL_0 ). Your brain determines what color something is based on what specific types of cone cells are being activated."
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m9n9yg | Why our shoulders accumulate so much tension? | Most of us like a random shoulder massage. It seems like we have a constant tension in this region. Specifically when we are stressed. So why the shoulders? Why not the legs, arms or stomach? And where does tension come from, anyway? | Biology | explainlikeimfive | {
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"It's one of the tradeoffs of evolving from 4 legs animal to straight up walking. Our spine get compressed and our shoulder's hang all the time so muscles have to work all day whit out support, or movement that release the tension. On your legs, you instinctively stand on one leg for a wile then on the other, so they Don't get as stressed. If there is something that I learned of this pandemic and the enforcement of home office, is that you can \"store tension\" on your lower back, and the importance of ergonomic office hardware.",
"This is because your arms are almost free-floating. What I mean by this is that the only bone that connects your arms to the rest of your skeleton SKELETALLY are the clavicles. And the clavicles are weak as hell― being the bone most prone to fractures. What in fact holds your arm to the rest of your body, are muscles. Multitudes of them. The most important of them is the trapezoid. The trapezius originates from the lower-back of your skull and your upper spine (neck and chest) and then inserts into the scapula (mainly) and a bit of the clavicle. The scapula is also a part of the upper extremity― the humerus (bone of the arm) comes and forms the joint with scapula. So essentially it means that the weight of the entirety of your arms are supported by the trapezius muscle. Now your legs don't hurt because they are supported by thick bones (femur and tibia) which have a lot of compressive and tensile strength, which muscles don't have― hence they get fatigued. It's the same with stomach (supported by the thickest part of the spine, the lumbar vertebrae) and the arms (supported by humerus, radius and ulna). Your arms are supported by the muscles (trapezius mostly) which get fatigued and hence hurt and feel good when massaged. Now guess which muscle forms the bulk of your shoulder?. Trapezius.",
"So first off I am a Massage Therapist. And this is actually incredibly easy to explain.....physically the pec muscles are just Two muscles one really big (Pec Major) and a smaller (Pec Minor) underneath it... now these muscle really only have one direction they go..... The back has a few muscle groups yes Traps, rhomboid, erectors, and the on the scapula you have the infra and supraspinatous teres major minor....anyways you get the just all these muscles have an attachment to pull the shoulders back in some way...... but they are all in different directions and not as strong as the Pec Major....... Add in the fact that humans are lazy and forward orientated everything we do is in front of us. Forcing the pec muscles to co tract and pull shoulder forward. Then the muscles in back being as weak compared try to pull back and just can't so they stay locked or get distorted by knots and over stretching.",
"In short a combination of, [Bipedalism] ( URL_1 ), and [bad posture] ( URL_0 )... holding your upper back muscles in odd positions restricts blood flow and causes knots and tensions to form. Messages increase blood flow, among other things like lymph and serotonin, which release tension. Arm and leg muscles tend to move and stretch more, and have better blood flow... although at the cost of increase joint load. The stomach is part of your vital organs which require a massive amount of blood flow, etc to function, so it is less likely to develop the same symptoms. ~~ > I should note, I am not a medical professional, this is just my best understanding of the symptoms you described."
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m9o1ow | Since energy is limited, and universe is expanding. Therefore, energy will be distributed throughout the new universe. Does that mean we are getting less energy to the expanding universe? | Physics | explainlikeimfive | {
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"Yes, that’s what the entire theory of entropy is. You’ll get diminishing returns of energy through every level, until we reach something called the “heat death” of the universe."
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m9ofy3 | Can animals of different species understand each other? | Is the relationship between animals of different species ‘understand’ and communicate with one another or is it like us where we can only can gauge off of behaviour, body language etc.? | Biology | explainlikeimfive | {
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"Think about how well you can understand what a cat is communicating to you. That's a lot more understanding than most species have for most other species, and it's still not much. Some animals do communicate across species, but only ones that have specifically evolved to do that and formed pseudo-symbiotic social relationships (for example, there are cases where you have two herbivore species who know the other species' warning calls mean predators are about). Even then though, whether or not they really *understand* the other species is debatable. They evolved to have a \"run away\" response when they hear the warning call, but that doesn't mean they understand that the warning call is a warning call.",
"Animals don’t have language the way that humans do. Their calls can carry meaning. Sometimes surprisingly specific meaning, but they’re not really “talking” to each other (with a few possible exceptions, though even there with demonstrably less complexity than human language). For most animals, vocalizations are going to communicate things on a similar level to body language. Growls, yelps, hisses, etc. And animals can, to some extent, interpret those. A lot of them, especially warnings, are specifically meant to be understandable as, e.g., threats even across species. But for the most part, animals aren’t communicating super complex ideas to even other members of their own species, and in the cases where they do, other animals are unlikely to be very good at deciphering the specifics with the possible exception of another species that co-evolved with to be good at understanding (in the way that dogs are remarkably good at picking up human language, for example)."
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m9ojjr | When we know what exactly causes Coeliac disease & the Genes involved, why's there difficulty in finding a cure? | Biology | explainlikeimfive | {
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"The answer is that we actually don't know exactly what causes Coeliac disease. We have identified two [genetic changes]( URL_0 ) that are strongly associated with Coeliac disease - 95% of Coeliac sufferers have these changes. But about 20% of people who don't have Coeliac disease also have the same changes. So the genes themselves are not enough to cause the disease. Furthermore, even if we were 100% sure it was only these genes that were causing the problem, we wouldn't necessarily know *why*. The gene we've identified is instructions for how to make a specific cellular machine - ie. a protein. We have a good idea of what this protein does when it's working correctly. It's made in immune cells, and is part of the system of machines that our immune cells use to identify things that shouldn't be in our bodies. So it makes sense that a mistake in building these machines would cause problems with that system. However, we don't know why the specific mistakes we know about cause these specific problems - or why they cause problems for some people, but not others. Basically, we have a good idea of where the problem is, but not what the problem is. We could try repairing the gene, but gene therapy is very very risky. Getting gene therapy wrong could mean fixing your Coeliac disease, but giving you another genetic problem (or worse, putting you at risk of cancer) in the process. This type of treatment is extremely young. I believe the first gene therapy product of any kind was approved only 4 years ago, and there's only a handful of treatments on the market. To top it off we don't even know if fixing the gene associated with Coeliac disease would actually treat the disease. It's possible that the gene changes set off Coeliac disease, but aren't necessary to keep the disease 'active'. That gene might be like a match for a fire. Once the fire is already lit, removing the match won't put it out. And understanding how a match causes a fire doesn't tell you that water will extinguish a fire."
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m9ov4c | How does the water level go down when you make instant noodles? | Cup of instant noodles, e.g., Maruchan instant lunch. You pour in the hot water, then wait a few minutes. The water level has gone down. Sure, the noodles have absorbed the water, but shouldn't the volume basically balance? The water level is significantly reduced after absorption, without the noodles expanding so much that the new level is equal to the level that the cup was initially filled with water. | Physics | explainlikeimfive | {
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"The noodles were filled with tiny air pockets from being fried. The water filled in those air pockets. The frying is why you can quickly rehydrate the noodles because they absorb water so fast.",
"You assume the noodle is solid. It isn’t. There are air pockets in them. That is where all the water goes. Sure a small amount will escape the cup from being boiled but most is in the noddles."
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m9p1il | what's the difference between a producer and consumer city? | i'm learning bout the economy of Pompeii and the debate surrounding it, but for some reason I just can't wrap my head around the practical difference between them. this is my first time posting here, so hope it's formatted right! :) | Economics | explainlikeimfive | {
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"Producer cities produce things. Consumer cities consume things. A producer city creates things and has an economy based on what it sells. The consumer city would have money coming in either from government taxes, military, or wealth made elsewhere."
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m9pb6m | m: receipts reacting to alcohol-based hand sanitizers | ELI5 why do receipts react to hand sanitizer? So I’ve noticed that the receipts I receive at stores turn dark grey whenever they’re exposed to hand sanitizer. Is this because the ink they’re typically printed with is alcohol-based and the paper is designed to chemically react? | Chemistry | explainlikeimfive | {
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"Thermal paper is made of a dye suspended in a matrix of paper the dye is exposed by a laser in the printer. The alcohol is essentially dissolving the matrix and exposing the dye."
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m9pyyv | When you burn a candle and the wax slowly disappears, where does it go? | Physics | explainlikeimfive | {
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"The wax burns, and in so doing it becomes mostly water vapor and carbon dioxide. The wick doesn't contribute much to the flame directly as fuel, but rather serves as a catalyst to allow the flame to sustain itself.",
"Some of it turns to liquid, which you can usually see pooling around the wick. Add the candle gets hotter, the liquid wax evaporates and becomes gas. This is how scented candles work. There's scented oils that get mixed in with the wax that evaporate and release their scent",
"Fun fact: Before the wide-spread use of clocks, people used candles to mark time. How? They would insert nails inserted into a long thin candle in a metal candle holder. They were inserted at specific points. They knew exactly how much of the candle would burn in an hours time and placed the nails accordingly. The candle would burn, it would burn down to that certain point at which point, the heavy nail would fall free, hitting the metal holder with a bang, marking an hour's passing.",
"The wax is actually the fuel source. It is converted into heat and carbon dioxide and perhaps other chemistry happens when it burns.",
"The wax melts, and combines with oxygen from the air to combust, producing carbon dioxide gas, and water vapor, and soot, and giving off light and heat. Frequently asked question.",
"It is burned. Wax melts goes to wick and evaporates there. After that, it is burned and provides heat and light."
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m9qiqx | So, how do sexual hormones and arousal even work? | Biology | explainlikeimfive | {
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"Pituitary gland is the master gland of the endocrine system (hormone producing system.) It secretes hormones that make other glands secrete their hormones that tell your body to do different things, hair growth, muscle development, breast development, metabolic regulators [mount up, lol] etc... Anecdotally, I am hypopituitary (low functioning pituitary due to a benign tumor) and therefore hypo -thyroid, adrenal, and gonadal. My body doesn't produce thyroid, cortisol, or testosterone in addition to some other hormones. I am on hormone replacement for all of the named, and will be my whole life. Specifically to testosterone: when I was off it for a few years I had zero sex drive, minimal and lackluster (to say the least) erections, weak urine stream, body hair loss, depression, tiredness, loss of muscle mass, etc... I still found women attractive, thought about sex, masturbated (no sperm production though), etc... The best way I can describe being an adult male who has the desire but not the drive or capability for sex is: it was like looking at a cake, and saying man that looks delicious, and I know I would love to eat it; but I'm just not craving anything sweet. Edit: I am not a Dr. And I probably messed/mixed up some terminology but I think I have the general idea"
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m9qjby | If the cells in our body are replaced every 7 to 10 years, why cant it roll itself back into a position where it worked better than it does now? | For example: Someone has a disease, why cant the body just reset itself to how it was before it had the disease to get rid of the negative effects? | Biology | explainlikeimfive | {
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"It's a false assumption that our body is replaced new cells every 7 to 10 years. Cells in your body can be divided into 3 types generally based on how they divide: 1. Always dividing: These are generally found in places that generally face a lot of wear and tear, like the skin, or the mucosa lining the inside of your mouth, stomach and intestines. Since they divide very fast, they can heal most wounds to them. That's why cuts or scratches heal so fast. 2. Not dividing right now, but can divide if and when necessary: Like your liver, or the lymphocytes (type of a white blood cell). That's why you can donate part of your liver and it grows right back. 3. Cannot divide at all: Examples are your neurons (the cells that make your brain and nerves), your heart muscle cells and the fat cells. That's why heart attacks and head injuries have a poor prognosis. Also, even dividing cells divide at very different rates. Skin regenerates very fast while some stem cells are pretty slow. So when they say the body replaces itself in 7 to 10 years, what they actually means that the dividing cells in your body have created enough cells to weigh as much as you. In reality what happens is, you shed off an immense quantity of cells that are damaged and cannot work. So, when disease occurs in the parts of body which cannot divide and repair itself, or the disease occurs at a speed higher than the rate of regeneration of cells, you get ill.",
"Cells don't have \"memory\" or perhaps a better word is cognition. The way it replicates is from the \"program\" encoded from the prior generation. Cells have no sense of \"this will work better if I reverted to an earlier model\" because there is no \"earlier model\" stored somewhere. It only \"knows\" what it inherited.",
"The body isn’t capable of going back to a previous version like computers can. Outside of it’s primary function, a cell’s only purpose is to create an exact copy of itself. This raises an issue. Each time a cell divides, it loses a small part of itself, specifically the telomeres, and eventually is no longer able to divide. This would tale place over a lifetime, until the individual has passed. From what I understand, there’s a decent amount of research going into slowing down the decay of telomeres, but I’m pretty sure there hasn’t been any major breakthroughs. Any success would probably dominate global news for a while.",
"New cells are made from old cells. If the old cells have a problem, the new cells will usually have that problem too."
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m9t19y | what is the more wfficient way to use a programmable gas-hot water heating sustem ? | Physics | explainlikeimfive | {
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"You're kind of looking at the wrong variable here. The job of the heater is to replace the heat energy that is lost through the walls of the house, and the loss is going to depend on the temperature difference between the inside and outside. How long the burner needs to be on or how often is really not that relevant because it all evens out at the end. All that's relevant is the temperature difference between the inside and the outside. b) might be more efficient if you heat the house to 22°C, then stop and let the house cool down, then start heating again once it hits say 20°C. But it's going to be more efficient because the average temperature difference and heat loss is lower in that situation. The average temperature inside over time is going to be closer to 21°C. But the energy consumption is going to be virtually the same as keeping the house at a constant 21°C. If you really want to save energy, you need to lower the house temperature, maybe at night when certain rooms don't need to be very warm, or in the morning when nobody is home. You can picture the house as a water bucket with a small hole in the bottom where water is leaking out, and the heater is keeping the bucket filled with water. The higher the water level in the bucket, the more pressure there is acting on the hole at the bottom and the more it's going to leak. Whether you have a constant stream of water refilling the bucket or whether you let the water level drop a certain amount first before you put in a bigger amount of water doesn't really matter. What matters is the average water level. Any time you allow the water to drop to a lower level, you slow down the leak relative to what it would be if you kept the water level constant. And if you're losing less water, you need to put in less to refill the bucket."
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m9u2zu | How does mixing two or more colors create a new colour? | Basically the title. I was wondering if there's hardcore chemistry involved in this and if not, how does colour mixing work? What is it that causes us to perceive a different colour when we mix two colours, say blue and yellow to make green? | Chemistry | explainlikeimfive | {
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"Mixing two paints literally just jumbles up the pigment molecules so that you see two colours at once. Your brain sees both blue and yellow colours mingled in a very very fine way and sort of interprets it to get a shade of green.",
"We only have three different colour sensors in our eye. Orange wavelength light stimulates both the long and medium and wavelength sensitive ones (wavelengths centred on the red and green regions of the spectrum) which we interpret as orange. Hitting them with a mixture of separate red and green wavelengths gives the same signals to the optic system so ends up being interpreted as the same colour."
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m9u4fu | why is it easier to take a nap than fall asleep for the night? | Biology | explainlikeimfive | {
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"You only try to nap when you’re feeling tired and like you need to sleep. You try to go to bed at night because the time dictates that sleep is appropriate, but that may or may not correlate with you feeling tired and sleepy. Thus you’re very unlikely to ever try to nap while in a state that would cause you to fail to be able to fall asleep, while you are much more likely to try going to sleep at night while in a state that makes it difficult.",
"Whether or not that's true depends on the individual. I have no problems falling asleep at night takes me 5 minutes or less I cant nap though. Even if I only get like 1 hr sleep at night. Falling asleep during the day is impossible for me, I can be dead tire with bloodshot eyes, my brain just wont do it lol"
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m9umtt | Why do the individual frames of a video look blurry, while the video itself doesn't? | I was going through a video of a car looking for its license plate number, and I swear I can just about make out that it's a license plate in the video, but it just becomes a blurry mess the minute I pause on any individual frame. Is my mind making up details? Is the blending/compression of the video codec reducing detail? Or is it some combination of factors? | Technology | explainlikeimfive | {
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"Have you ever tried looking through a mesh wire screen and couldn’t get a good look at what was on the other side because too much was blocked by the metal screen, but if you move your head back and forth while continuing to look through it, the screen practically disappears and you get a fuller picture of what’s on the other side? Your brain is building the image of what you see not just from what is hitting your eyes in a single instant, but from a combination of what you’ve just seen and what you expect to see. Any series of images you see in a tight enough window of time kind of get smoothed together into a continuous image, instead of a series of individual images, which is why video and animation works. Part of that means that, while each individual frame could lack some degree of detail from, for example, motion blur, your brain will be averaging the information of several frames together to get a clearer picture of what it is that is moving than exists in any single frame on its own. It’s also possible that, depending on how you are viewing the footage, you aren’t able to scrub through it literally frame by frame, and some of the frames being skipped have more information in them than the ones being displayed to you. This is particularly likely if it’s a video being streamed to you rather than one saved directly to your computer."
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m9vxm8 | What exactly is grief, physically? | I saw this post about memories and I’m curious | Biology | explainlikeimfive | {
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"We should start with the obvious point, and that it's a mental thing, and we don't know everything about the brain. But grief is the feeling of deep loss or regret, brought about by the brain being physically used to someone or something's presence, which is no longer there. It messes with your rhythms, it messes with your thoughts, and you end up feeling it as aches in your body and heart. Over time, you readjust to life without that missing element, and the grief subsides. But memories of the person rekindle that feeling of loss, similar to how being around a smoker makes you feel a new craving for cigarettes when you quit years ago, which is why grief over a lost loved one is so much more powerful than something more easily replaceable, like an old car. The more memories you have, the harder it is to leave it behind."
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m9x55k | Do Ancestry tests like 23andMe misrepresent what genetics is able to objectively say about a person? | Technology | explainlikeimfive | {
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"No - but anyone looking at genetics need to understand that different tests have different qualities of results AND we know a tiny % of what our DNA codes for. On top of that, the knowledge both of genetics and the interrelationships between genetics and other parts of health are changing rapidly. If you’re wanting to make healthcare decisions use a modern clinical genetics test (not the 20+ year old tech from 23andMe) and work with a generic counselor. Ensure that the test and group you work with are regulated and part of the medical ecosystem and at a minimum get what’s called an Exome test.",
"Could you be more specific? They are private companies with a sales pitch, so you have to do your own due diligence. They both find relatives who are third cousins and closer pretty easily. Both try to assign nationalities. Those results can be a bit fuzzy. They aren’t bad when the percentage is at least an 1/8. I wouldn’t trust anything under 2%. That’s just noise. 23andMe adds whether or not you have certain markers associated with health risks. I’d ask a doctor how important or accurate this information is.",
"If you’re asking a legal question of these companies like 23 & Me ‘’misrepresent” themselves, that’s a question for /r/LegalAdvice. If you’re asking do they overstate the tests ability to identify genetic medical problems, yes they give a greater impression of what they can do by using words like “can” and “may.” I *can* guess if anyone has cancer and I *may* be right because with my binary guess at a large enough sample size I’ll get some right. If you want as accurate as possible a test for genetic markers for disease, then go to a doctor. If you’re asking is their schtick of telling you what percentage ethnicity/race you are, again that’s kind of accurate and kind of not. The machine doesn’t have a magical way of knowing, its just checking certain markers against the database and updating that when they know they have more data. If you want better accuracy than they offer, go to a professional who finds family history. Although, again, to a degree any fanily history can only be as good as what is already known and what public records ever did, and still do, exist. I know that isnt the best answer, but your question is vague.",
"I do genealogy and for me it is a great tool because I can make my tree fatter which also helps make it taller, as someone may have found a common ancestor's parent that I haven't been able to find. I have traced my family lines back at least until 1800s and I once went through it an figured out which countries each line came from. I had about 36% unknown origin countries. But based on how long ago they were in the americas I have a good guess on where they were from. So the result that I found in my tree are basically the same as my dna results. There are some things to that you may consider misrepresented. 1. At 7 generations or more you share 1% or less dna with a single ancestor so the result can't really tell you where your ancestors were 1000+ years ago. 2. The ancestry and 23andme do not have a lot of sampling from people who lived 500 years ago. So that means the results tell you more about where your ancestors descendants live now. Which might not exactly be the same as where they lived at one point. 3. Likewise the results can vary depending on who has taken the test. Like when I first took the test it did not say I had any ancestry from scandinavian. But now I have about 1% with more data points the tests are better able to be more nuanced. This is another reason that it would be nice to have more data points from people who died centuries ago but I don't see either company digging up graves. 4. There is a point in history where everyone alive today shares all of their ancestors. With math this point can actually be surprisingly early and genetics is supporting a 5,000-15,000 years ago timeframe. So at that point you would be related to about 80% of the people alive. The other 20% would not have surviving descendants. This makes ethnicity sort of moot. 5. DNA can be tricky. My results for traits said people with my genes are likely blond and have wisedom teeth. I have brown hair and I didn't have wisedom teeth or two of the next molars. But a recent study that was published found 50 new genetic locations for eye color. Ancestry and 23andme are likely only looking at one or two locations for certain traits. So the main genes that code for hair color likely are blond genes but since there are many other genes that also code for hair color they likely changed the end result. So if something like wisedom teeth that is pretty simple can have different outcomes than something more complex like ethnicity is probably not better."
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m9x7et | how can a tiny tug boat push/pull huge tankers and cruise ships? | I get that plane tugs have huge tyres and tonnes of torque, but a boat? A tiny boat? 🤷♂️ Thanks | Physics | explainlikeimfive | {
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"The engines and propellers of those tugboats are comparable in size to those of the huge tankers. The tugboats are smaller not because they have smaller engines but because they do not have any cargo holds or giant fuel tanks. A tugboat is literally just a giant engine and propeller in the smallest boat possible. Not unlike plane tugs.",
"Tugs are designed to partially submerge themselves to \"grip\" the water and allow them the leverage needed to push. Couple that with a beefed up engine with lots of horsepower that's precision controlled with on board computers and there's no ship too big for them to move around.",
"They have a lot of power stashed in that little package. Big cargo and cruise ships also have a lot of power, and might hit say 35 knots, while a tug boat has enough power to move them 8-10 knots. That's perfectly okay, because we aren't looking for speed when bringing a ship to port, we need agility and the ability to react a little less slowly, which tugs offer.",
"The size of the boat doesn't matter. The only things that matter are the engines and the propellor. It makes no difference if you put the propellor and engine in the big boat, or a small boat that tugs it.",
"Most ships are trying to do multiple things. They want to move people/cargo, they want to go a long distance, and they want to move quickly. This means most of the ship is allotted to cargo/passenger space, and lots of food/fuel/water for the long voyage, and a pretty powerful engine so they can do 20-30 knots in relatively rough seas. A tugboat has a single job **Push** It doesn't need to go far, it doesn't need to carry anything, it doesn't even need to go fast, it just needs a massive engine so tugboats have a far higher percentage of internal volume dedicated to engine space. Moving a ship in water isn't terribly difficult, but the faster you want to go the more difficult it gets, if you just want to go fast you'll need tens of thousands of horsepower but if you just want to go at a few knots then a few thousand horsepower will do the trick. A big propeller to efficiently get that power into the water at low speed and a tug with 3000 HP is plenty to guide a big cargo ship at just a few knots. For a sense of power density here, a modern tugboat will have 3000-6000 HP and weigh in around 100-300 tons while a WW1 era *battleship* generally had 30,000 horsepower while weighing in around 20,000 tons, but the tugboat never really has to leave its harbor so it can be 100% focused on tuggin"
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m9xyja | Why do we lose muscle mass when we stop working out? | Biology | explainlikeimfive | {
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"Your body basically goes “Oh, you’re not using that? Lemme just take that off your hands so the materials and energy can go elsewhere since you’re clearly not using them” It’s called muscular atrophy",
"By working out you’re telling your muscles that they need to be strong to keep doing this hard work. But when you stop working out your body notices there is less need to use so much energy in keeping your muscles strong. So then you begin to lose some muscle mass.",
"A lot of people think they've lost muscle when in reality they've lost the glycogen stored within the muscles. Instead of losing pure muscle, they're actually just not as full of glycogen, one of the reasons why \"muscle memory\" while starting to work out allows you to more quickly look bigger and lift bigger than what initially took you to get there. As long as your diet is maintained in a good healthy fashion, true muscle loss isn't too expected unless you're in like a full on catatonic state not moving at all"
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m9y15y | How is it that a given website/service provider seemingly doesn’t know your password when you create an account, but it still knows it when you are trying to change it and it says “You can’t use a previous password” ? | Technology | explainlikeimfive | {
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"The result of a cryptographic hash function is what is stored and compared when you entered the password. This ideally produces a unique output value for any given input, but the original input can't be figured out from the hash value alone. However, if you enter the correct input value, the hash value will match the stored value, indicating a matched password entry.",
"Your password is (hopefully) not stored by the service. They will add some random characters (called salt) to your password and then transform it into some data that looks nothing like your password ,using a cryptographic hash. eg: using the common bcrypt hash, the text \"password\" becomes: * $2y$12$5.a9GcsptRjdHuDxJZnFgOOpjVX7ESdPSsXQ7kA6SKyMfrVJGNv0O or again with different salt * $2y$12$Dh9IoY4KyLHMu8PjmUvdOuJ9rlIIEHEB4FuQKUV7ngy4mkbaiyOi. It (hopefully) should not be possible to work backward and find out what text created this hash. However, it is possible to determine if a hash is a \"match\" for a given password. This is what the service does, checks if your new password matches the hash for the old password. It's fairly time consuming (even on GPU) for a computer to determine if a hash matches a password. Not a big deal if we only need to do that when a user logs in. However hashes are there to protect against the event someone steals the entire password database. To illustrate this, I give you the hash for my reddit account password: * $2y$12$mZ7hep8QvCd5bu0hmVa8iuTIQ44cd4rvGpkPvotarRgx4dGmHajku I can do this safely because my password is not a common word or password. To \"brute force\" it out by testing against lots of strings, until you guess the right one, will take your computer about half a year or more. The purpose of the random \"salt\" is that you don't want the same password to produce the same hash twice. If the system does not use salt, then a pre-computed dictionary of hash keys for common passwords would allow a someone to quickly discover passwords for a large number of the users in the database they stole. Such a dictionary is called a \"rainbow table\" and is still used against many poorly designed login databases.",
"The website keeps track of your previous password hashes: which is a piece of data generated from your password that can be used to check if a password matches, but which can’t be decoded back to the original password. Because the hash can’t be decoded back into the original password, they genuinely don’t know what your password is. However, by checking the password you entered against your account’s previous password hashes, it can tell you if the password has been used before.",
"When you give then the password, they do some complicated math with it that's designed to be easy to do but almost impossible to reverse. This is called Hashing. They store the \"hashed\" password, but not the one you gave them in plain text. When you then want to log in they do the same math again and compare the result. This way they can tell if its correct or not. The same happens when you try to change your password.",
"To clarify what exactly a hash is, it's a one way function, where you can encrypt the data but not decrypt it. For example, say my password is ABCD. A way (a terrible way, but still a way) to hash is to assign each letter a number then add them up. So I can add 1+2+3+4 and get 10. This is not reversible. If I give you 10, my password could be DDAA, CCCA, etc. There's no way to tell exactly what it was. A good hash takes a while to perform (for a computer) and changes the output completely with small changes to input. Optimally, there would be no way to map the output back to any input, but hashes do get broken occasionally. The important thing here is that the password provider doesn't know your password. You type it in your web browser, and before any data goes out, it gets hashed. The hashes are compared, and if they match, it's the same password. You can think of a way to attack this by just having a massive table matching passwords to hashes. So I can take your hash and look it up in that table, and find your password. The way to counter this is just to attach some junk data to the end before you hash, called a salt. This makes that table useless, because you might have 'password' but you won't have 'passwordjgbrhsizjcufbrbskfif' in your table. A theoretical problem with hashes is that all inputs map to a limited output space, so there can be collisions. Multiple inputs map to the same output. This is bad, but unavoidable. With our hash function, you can see that if you just keep typing strings of As, you will eventually hit all hash numbers. For good hash functions, this isn't really a problem, as collisions are so infrequent it's essentially irrelevant, at least in the password management space."
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m9ysld | Why does a burn still feel hot even after running it under cold water? | Biology | explainlikeimfive | {
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"The damaged area is more sensitive, meaning nerves are firing off more signals with less stimulus required, and the area is inflamed meaning the body saturated the area with blood to jumpstart the healing process. Lots of warm blood+ extra heat sensitive nerves = constant signals that the area is hot.",
"When you can’t feel the heat and pain is when you need to be really concerned. When you have a burn bad enough and there is no pain is time to go to the hospital. Ironically, the more pain you are in, the less severe(typically) the burn is.",
"The nerves have already been damaged from the heat. The sensation is the damaged nerve firing uncontrollable constant signals to the brain. Not unlike a skipping record.",
"Your pain receptors and signaling pathways are sensitized following noxious stimulation (e.g. burn). They are more excitable, so the threshold for \"pain\" sensations is lower. This can lead to \"hyperalgesia\" (previously painful stimulation is now more painful) as well as allodynia (previously innocuous stimulation is now painful). Related, I believe that thermoreceptors can be activated by both extreme heat and cold (as well as certain chemicals, like capsaicin in chili peppers and menthol). This is why you might feel \"burning\" sensations from cold exposure or handling chili seeds.",
"Speaking from personal experience. Like previous commenters said the nerves are on fire and the cold water stops the burning but ALSO it helps to lessen the intense pain by deadening the sensation. I once had a burn from high school chemistry class, heat not chemical, on all four fingers of my right hand. School nurse gave me an ice pack to keep on it. I had to go home because I literally could not function even after an hour with the ice pack. Once home I sat with my hand in a small cooler filled with ice water for about an hour. Every time I took my hand out the same intense throbbing pain came back. Finally I made the choice of this is my life now vs fuck it let's see what happens. I took my hand out and focused on the pain to see how long it would last. It started to hurt less and less and after a few minutes it was much much better so I proceeded to enjoy some daytime TV and video games. My suspicion is that I was delaying the natural response of my body's nervous system that allows the brain to ignore constant signals and once I stopped trying to focus on stopping the pain and just feel it while distracting myself, my body did its thing and started healing and coping.",
"Heat is the transference of energy. Basically your skin absorbs the heat. The cool water helps the heat leave the skin. That’s why you should keep running it under cool water (not very cold) until it doesn’t feel hot anymore, because most of the energy will have left. Depending on the severity of the burn the energy could have gone down to the lower layers of the skin. So if it happened recently and it’s still “burning” put it under water again, for up to 15 minutes. The person who said the sensitive nerve thing is only correct after the heat has initially dissipated. But if the area is constantly hot seek medical attention (I’m a healthcare worker-not a doctor or RN) because the area may be infected. Don’t put ice on it, you can harm the surrounding skin more.",
"the short answer is that your skin receives a lot more blood when damaged, and the extra blood makes it hotter. the answers more complicated than that and has more factors, but thats a big part of it and the easiest to explain",
"I will say this as somebody who has been burned a lot because they work in a dry cleaning plant the best thing to do is definitely do not run it under cold water just let it sit and the body will heal itself",
"Also, you need to continue holding the burn under cool, running water until the burning sensation stops.",
"Burns feel hot even after running cold water over your finger because your finger has been burned."
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m9yyh1 | Why is cancer such a difficult disease to cure? | Biology | explainlikeimfive | {
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"Because cancer isn't really a single independent entity, which would be easy to target and fix. Cancer is a malfunction of the cell, causing the cell to replicate and spread in ways it's not supposed to. Since these are \"normal\" cells, just acting improperly, that makes them hard to stop in a way that doesn't hurt other non-malfunctioning cells. If cancer was some sort of completely unique and isolated type of organism, then it would be easier to formulate treatments and drugs to fight that specific entity. But since they originate from normal everyday cells it's hard to differentiate amongst all the normal ones. It's like trying to find the bad guys in a group of people when they are all wearing the same clothes.",
"There are a few reasons for this. Firstly cancer is not a single disease. Cancer is not contagious so every time someone gets cancer it is a completely new development and a completely different disease that the doctors have never sen before and therefore they do not know its weaknesses. So the doctors are left trying a bunch of different cures hoping to find the right one. This is similar to how we have not cured the common cold because it develops much faster then we can develop cures for it. Except cancer develops even faster as each person have a different cancer entirely. Secondly cancer is a disease caused by the body's own cells. We can cure a lot of diseases by helping the immune cells detecting foreign infections bu cancer is not a foreign infection and will therefore be undetected by the immune system. Similarly if we try to find medicine which only kills the cancer cells the issue is that what kills the cancer also kills the healthy cells because they are one and the same. We might one day be able to cure most cancers. We have made a lot of progress in coming up with the right combination of treatment and the survival rate for cancer is now much higher then it used to be. There are also a lot of breakthroughs in cancer research. Most breakthroughs do not make a lot of impact, especially not on its own. But there are a few breakthroughs which does show quite the promise and might be able to cure at least half of the cancers within maybe twenty years.",
"Cancer is, in a very ELI5 way, your cells that multiply without control. Your body is very special, but not flawless, so very rarely, there are cells that dont die when they should. The treatment is to kill all the very numerous cells that multiply a lot, and thats the problem, that the cure cannot \"differenciate\" between what is cancer and what is not Thats also the reason why people with cancer in hospital (in treatment) are bald and so palid, blood and hair cells are one of the fastest multiplying kind of cells, and the \"chemo\" or \"radio\" therapy arent that precise and cant know which are the \"healthy\" cells and which are the cancerous ones Becayse of that, cancer is so hard to cure, because if you are too \"aggressive\" killing the cancerous cells, you might kill the person, because the \"cure wasnt precise\"."
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m9zk7z | why do we automatically change our voices to talk to babys and pet? what causes that? | Other | explainlikeimfive | {
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"It's a form of code switching, and we do it all the time! Not just for babies and animals, but those are more exaggerated examples. Code switching is when we change our speech according to the situation. Think about the way you'd talk on the phone with customer service vs with a close family member. You're using the same language, and many of the same words, but there are subtle differences. The coolest part to me is one you mentioned - we do this without really thinking about it!",
"Neither babies nor pets can understand the words that we're saying. They can understand tone, body language and mood though. So even though we can't tell them we're friends, we can sound reassuring and friendly.",
"Baby-directed speech and pet-directed speech are similar because it actually does get the animals/baby's attention and it holds it for longer than normal speech patterns. However with baby-directed speech we tend to exaggerate the pronounciation of words but we don't so this with animals. so this suggests that it can also be a tool to help teach babies to speak. URL_1 URL_0",
"When we switch tones to smaller creatures it shows them we are friends. Pets and baby’s don’t understand our words so we use a soft tone to show we mean no harm.",
"It's something we are conditioned to do. Anyone who can relate to this just grew up in a society where this is a practice. Many of us just do it without even thinking about it. What other things are we doing without even thinking about?"
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m9zmf9 | How is audio transmitted from my phone to my wireless earphones? | I understand that both devices are equipped with Bluetooth modules, but how the sound is able to play instantaneously baffles me. | Technology | explainlikeimfive | {
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"Fundamentally it is just a radio transmission of data from your phone to the earphones, but there is a reason it took years to go from radio sets to Bluetooth headphones. Those chips are doing a lot and the process is very layered. How do you account for all the other signals bouncing off walls etc? How do you encode the sound as data efficiently? What do you do if you lose a packet of data? How do you minimise the power usage so an earbud works for a whole day? And a bunch of other issues that all got solved and standardised one by one to produce what essentially seems like magic. But yeah, radio waves."
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