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nho6o6 | Why is it that we cannot make a sound that sounds like a crowd on our own? If different sounds are just varying wavelengths, and assumedly the noise that would come from a speaker to sound like a crowd is generated as a certain wavelength, why can we not make sounds like this with our mouths? | Biology | explainlikeimfive | {
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"The sound of a crowd is close to “white noise”, which means that there are sounds present in it of almost ALL wavelengths within a certain range. One human can’t produce that, because one human does not possess the vocal instruments to produce sounds of all wavelengths at the same time.",
"Sound is not just a specific wavelength. It is a combination of different wavelengths at different amplitudes. The sound of a crowd is generated as each member of the crowd generates a unique sound as a unique set of wavelengths. And when these are combined you get thousands or even millions of different wavelengths of sound combined. This is usually called a white sound which parallels how white light is a combination of all the wavelengths in the visible spectrum. Most of the ways we generate sound with our mouths is only generating a few different distinct wavelengths of sound at a time. However it is possible to shape your mouth in such a way that the airflow generates lots of turbulance and therefore a lot of different wavelengths which approximates the sound of a crowd. But it can be very hard to do this in a way that sounds realistic."
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nhqc7x | If the brain can only survive 4-6 minutes without oxygen, how can freedivers hold their breath for 8+ minutes? | And what about people like David Blaine or Tom Sietas? Sietas held his breath underwater for over 22 minutes (world record). I know they train for it like months and even years, but doesn't holding your breath = no oxygen to brain? Permanent brain damage apparently occurs just after 4 minutes of lack of oxygen to the brain, so why are freedivers left generally unscathed after 8 or 10 minutes without air? | Biology | explainlikeimfive | {
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"The level of oxygen in the body is dependent on two things - how much oxygen is in the bloodstream, and how fast it can be used by the body. So in the case of David Blaine, he breathed pure oxygen for good period before his record attempt, and through practice increased the time that oxygen could last for by slowing down how much he uses that oxygen. Free divers also are helped by the body slowing down in cold water their pulse rate, and how their body uses energy. These all slow down so free divers (after much practice) can hold their breath for longer than people on dry land.",
"They have increased their lung capacity and modified their metabolism through exercise and training. Think of it this way, there are drunks and drug addicts who come into the Emergency Room with blood alcohol levels that would kill an ordinary person, but because they have been abusing themselves for so long their bodies have adjusted. If a person who had never shot heroin took as big a dose as a long term addict, the first timer would die, but the long time user would just be normal.",
"Because all the oxygen in your blood isn't used up immediately once you start holding your breath. Free divers train and perform exercises to increase their lung capacity and lower their heart rates so their bodies use up less oxygen.",
"Divers can breathe in as much air as possible before diving. That air will supply them with oxygen for a while. Also they can hyperventilate (breathe in and breathe out strongly and rapidly for a while) before diving, so that their blood will become saturated with oxygen, keeping the brain oxygenated even if there’s no more air. If the brain stops getting its oxygen the person usually loses conscience within mere seconds (like if an airplane depressurizes while at high altitude). Obviously divers don’t want that to happen, so their brain keeps getting oxygen. If a diver has lost conscience they’d quickly drown. The 4-6 minutes survival time means that oxygen supply to the brain has to be restored within that timeframe to avoid death.",
"If you take a deep breath first, you fill your lungs with air. When you hold your breath, you still extract oxygen from the air in your lungs, so the oxygen supply to your brain isn’t cut off immediately. The number of minutes you survive without oxygen is based on a cut off. E.g. empty lungs or a cut off blood flow so the oxygen rich blood can’t be transported to the brain. At least that is what I recall. Feel free to correct or educate me if necessary.",
"As you dive down, the water pressure increases and the Partial Pressure of oxygen in your lungs and blood also increase, keeping it at sustainable level. Even as you metabolise O2 to CO2, the remaining O2 is still at sustainable partial pressure. As you swim up, the pressure drops and there's risk of shallow water blackout.",
"I want to add to the other comments that when talking about 4-6 minutes without oxygen, it is also without blood supply (e.g. in case of cardiac arrest / ventricular fibrillation). While the divers still have a working circulation, oxygen is still supplied to the brain. Though indeed over time the saturation gets less, it's not like the moment you hold your breath your saturation becomes 0. So there is technically still oxygen supply there.",
"When you hold your breath there is still a lot of oxygen in your blood and that gets carried to your brain. For example when choking someone and you apply too much pressure on their neck so the blood can't flow to the brain anymore then the choked person will be unconscious after just a few seconds because of the lack of oxygen. You don't get unconscious from holding your breath though because your blood is still flowing and carrying oxygen into your brain. Of course, if you hold your breath long enough then there will be no oxygen left in your blood and you will lose conscience and eventually your brain will die off.",
"It is 4 minutes after the blood oxygen level is below a critical level. Your body doesn't actually react to lack of oxygen it reactors to increased amount of CO2, that is what gives you the feeling of needing to breathe, it doesn't mean that you are running out of oxygen. Now imagine that you are running, you start to breath faster than if you were walking. This is because you are using more oxygen. Now. Try running and hold your breath, as long as you can. You can keep your breath for longer when walking. Makes sense doesn't it? Now what free divers and people who do extreme feats that require you to hold breath do is that they relax and calm their bodies, and use breathing techniques to pump as much oxygen in to their body as they can. They have also learned to deal and resist against the urge and struggle caused by build up of CO2. You can actually try that yourself. Sit on a comfortable chair. Close your eyes, breathe deeply few times and relax as much as you can. Then just hold your breath. You can practice this skill and get quite good at it. This is often used in things like meditation and yoga. Now. When your body runs out of oxygen, that is below the critical level, you pass out. This is where the timer of 4-6 minutes start. After that it is safe to assume that damage to the brain and other vital organs start to happen. Each passing second increases the probability. Now. What is interesting is that if you cool your body temperature, the chemical reactions that happen in your cells slow down. This means they'll use less oxygen. The chemical reactions. This is actually used a lot in medicine, during long surgeries if blood supply has to be cut for some reason, or if there has been severe trauma. Now. If you do cold water free diving. Your body temperature drops, which gives you an edge. You use less oxygen. The current world record holder is Finnish Johanna Nordblad (Torille!) who dove 103 meters under ice in the time of 2m 42s, without fins or a wetsuit."
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nhqxkn | The different type of diamonds | I’m currently hunting for an engagement ring for my girlfriend but I don’t understand all the gradings. Like what does H-D mean and VS1? How do they even decide how much a diamond is worth? | Chemistry | explainlikeimfive | {
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"Colour, clarity, carat and cut. Colour goes in an alphabetical scale, typically starting with D for a very pure white, towards Z it becomes yellow, possibly synthetic diamonds Clarity is more confusing, but pertains to how many defects are in the diamond. The best are flawless and internally flawless, then you get onto the letter scale which uses V, S, and I. I dont know what they mean, but you want more V, maybe some S, and no I. VVS is a good clarity diamond Next is carat and thats pretty much the weight and size of the diamond, and is quite simple, bigger number, bigger diamond. The last C is for cut, which doesn't apply to the shape the diamond was cut into confusingly, but they quality of the cuts made, from excellent to poor, again ots quite self explanatory. The higher a diamond places in each of these categories the higher the price. But certain brands can add to the price tag too"
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nhsfjm | How did we find the number of electrons, protons, and neutrons in the past if we didn't have the atomic number or weight? | Chemistry | explainlikeimfive | {
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"If you measure the density of gases (at the same temperature and pressure) you'll notice they have simple ratios. Helium is twice as dense as hydrogen, the lightest element, nitrogen is 14 times as dense, oxygen is 16 times as dense. Similarly, you can notice that e.g. 1 gram of hydrogen reacts with 8 grams of oxygen to form 9 grams of water. They always react in that ratio. If you have more hydrogen then some hydrogen will be left over, if you have more oxygen then some oxygen will be left over. It's not the same ratio of 16 from above because water is H2O, i.e. has twice as many hydrogen atoms as oxygen. Add many more reactions and you can assign relative masses to the atoms. People sorted elements by mass and noticed that they form patterns. As an example, silicon (14th lightest element) reacts similarly to carbon (6), phosphorus (15) reacts similarly to nitrogen (7), sulfur (16) reacts similarly to oxygen (8), and so on. People started arranging the elements in what's now known as periodic table. That's a powerful tool, because now you can notice if you missed an element in between. If e.g. your \"17th element\" reacts like the 10th (i.e. not at all, because #10 is neon), then it's probably the 18th element and you missed #17. With better mass measurements people noticed that: * sometimes the mass order is different from the order in terms of reactions * some elements have atoms of different masses This suggests two separate mechanisms. One that's responsible for the chemistry (element number), and one that can influence the mass. If you shoot particles at atoms you can notice that they have a very massive but tiny positively charged nucleus and then negative charges (electrons) around them. The electrons are responsible for the chemistry. An electrically neutral atom must have as many electrons as protons, so the element number is simply the number of protons. Regular hydrogen is simply a proton. Now you can put everything together: Hydrogen has one proton, let's call that mass \"1\" (a small fraction of atoms has one or even two neutrons). Helium as second element has 2 protons but mass 4, so it needs to have two neutrons (a small fraction of atoms has only one neutron). Carbon is element 6 and has mass 12 - > 6 protons and 6 neutrons. Didn't I say helium gas was twice as dense as hydrogen? This was indeed cause of some confusion early on. The problem is that hydrogen, oxygen, nitrogen and a few more gases form molecules of two atoms each, while helium does not (because it basically never reacts with anything). Today you can simply put something in a mass spectrometer to measure the mass directly: You measure how much atoms are deflected by magnetic fields if you remove one of their electrons.",
"By analyzing the weight ratios of components in chemical reactions. Like H2 and O2 give you H2O, but it’s also possible to make H2O2 from those same components, given that you supply twice as much oxygen for the same amount of hydrogen. Why could that be? There aren’t that many possibilities to consider before you arrive at the corresponding chemical formulas for these compounds. And comparing the weight of H2 and O2 participating in the reaction you can figure out the ratio of the atomic weights of these elements. Piece by piece you’d be accumulating such information, until one day you figure out the periodic table. And after that it gets even more straightforward.",
"Early chemists used hydrogen as a base unit. Hydrogen was \"1\" and everything else was multiples of that. Since the natural state of atoms is electrical neutrality, they must have the same number of electrons as protons. This use of hydrogen as a base unit didn't always work out, but that was remedied when we discovered the neutron which accounted for those discrepancies."
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nhsthn | Why does the shower curtain liner take on a life of its own and attack me sometimes, but not all the time? | Physics | explainlikeimfive | {
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"Whether it attacks you or not may have to do with the temperature gradient between the air inside the shower and the air outside of the tub. A large gradient might generate some air currents. Another option is if it's a cold shower there might be some static electricity being created which might cause it to jump and attack you. Also, if you shower drunk or while getting drunk, it may from your frame of reference seem as if the curtain is attacking you, but simultaneously from the curtain's frame of reference, you're attacking it by falling in to it repeatedly. If you live on a fault you might substitute the concept of tremor for that of getting drunk. Finally if you have a cross-current in the bathroom of the kind generated by having windows open in different areas of your home or bathroom, shifting breezes might cause the shower curtain to jump you. edit, I also like [the bernoulli's principle suggestion.]( URL_0 )",
"Without seeing your shower, it's kind of hard to determine, but when my shower curtain encroaches upon my personal space in the shower it's because of Bernoulli's principle. Bernoulli's principle says that a fluid in motion has less pressure than a fluid that isn't in motion. When your shower is on and water is flowing, the motion of the water causes an air pressure differential between the inside of the shower and the outside, which causes air to push the shower curtain in. You can overcome this by increasing the weight of your curtain, or by getting it wet.",
"Hot water make air warm. Warm air move up to ceiling. Cold air move into place where warm air was. Curtain dragged by the cooler air. Science or something.",
"Convection air currents. Basically it boils down to the fact that you're using hot water to wash yourself. That hot water heats up the air within the shower area and hot air rises to the ceiling. Because the air is rising to the ceiling it leaves a void and cool air closer to the floor is forced to replace it. The cool air follows the easiest path, normally your curtain sticks to the tub or shower surround but when the air above the shower curtain becomes too warm, then the cold air is forced between the curtain and the tub/surround. That lifts the curtain away from that area as the air forces its way through. Factors that feed into it not happening is the curtain is really stuck onto the tub by moisture or magnets.",
"Shower curtains are very territorials and will attack any threat on sight. But shower curtains are also very, very heavy sleepers and a lot of noise is needed in order to awaken them. If you have your shower during the shower curtain paradoxical sleep, you may have a chance to finish your shower before it awakens. (Sorry)"
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nhtfww | what is the difference between LED, LCD, OLED, QLED, and plasma? | Recently saw a comment stating some difference between OLED and LCD. Just wondering what the differences are in the rest of the major TV types | Technology | explainlikeimfive | {
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"A lot of it is deliberately misleading branding from manufacturers, there are really only 2 main TV technologies right now (LCD & OLED) * **LCD: Liquid crystal display**. The same technology used for the display in digital watches and alarm clocks, but miniaturised to the point where they can make up the pixels of a screen. The pixels don't produce their own light so they need a backlight. Old LCDs used CCFL backlights (flat fluorescent lamps) but since about 2010 they have used LED backlights. To market the newer backlight technology manufacturers commonly call these \"**LED TV**s\", even though they are just LCDs with a better backlight. **QLED** is Samsung branding for LCD TVs that have 'quantum dot' films inside them, it's a layer between the backlight and LCD layer that enables the tv to produce more colours with higher brightness. A problem with LCD is that when watching dark scenes some of the light from the backlight still bleeds through, making blacks look grey (especially at high brightness settings). Local dimming is a technology where the backlight is divided into sections that can individually be made lighter or darker, allowing an LCD screen to look better in dark scenes, **Mini LED** is the term for a perfect version of this local dimming technology where every pixel has it's own individual backlight, this is the newest LCD technology branding you will start seeing in 2021 TVs, but it's still LCD at it's core. * **OLED: Organic Light Emitting Diodes**. This is a totally different technology to LCD, the pixels themselves produce their own light so there's no backlight. This means there's no backlight bleeding through during dark scenes allowing inky blacks and amazing contrast. Also because there's no extra layers needed for the backlight, quantum dot layer, etc OLED TVs can be extremely thin. The downsides of OLED is that the pixels break down over time and static images can get burned in, also they tend not to be as bright as LCD screens. That said companies have been improving the technology every year making these problems less and less prevalent. * **Plasma** screens were an older technology which worked by having thousands of pockets of a gas that would turn into plasma and produce light when an electric field was put across them. It offered many of the same benefits as OLED since each pixel made it's own light, but it was costly to manufacture compared to LCD TVs, and then OLED came along offering all of the same picture quality benefits and made it truly obsolete. There is a new upcoming TV technology called 'Micro LED', which is a TV made up of millions of tiny LED lights. It has the same benefits as OLED but with the increased brightness and longevity of LCD TVs, so it's like a best of both.",
"LCD is any display that uses liquid crystals to display an image, that's basically the next step after CRT's. Those liquid crystals can display colour, but no light on their own, so you need a light source. On never displays that's always done by using LED's, that's why those displays are often called LED-screens. They still use LCD's though. OLED is again the next step, by using organic liquid crystals who have the ability to emmit light on their own, so you don't need additional LED's and have a better picture with far more contrast. QLED-screen are basically still using \"normal LCD's\", but rather special LED's for the backround light. Those aren't white, but can take on every colour, which means that the colours on the screen are also better. You don't have the same superb contrast OLED's have though. Plasma-TV arent using liquid crytals as pixels, but basically small chambers filled with gas. There are three chambers for each pixel, containing different gas for displaying either blue, green or red. By connecting an electric current to them you're turning them into plasma and thus visible light.",
"Woohoo, I get to bust out [my 9-year-old response]( URL_0 ) to this question again! That response covers LCD, LED and Plasma. The other two you mentioned are QLED and OLED. * **QLED** is essentially the same as LED, but a special \"quantum dot\" color filter is added to the screen that greatly expands the color space that the TV is capable of displaying. The Q stands for \"quantum\", referring to the quantum dot filter. * **OLED** is a completely different technology. It stands for *Organic Light Emitting Diode*. How exactly it works is a little beyond the scope of an ELI5, but the key thing to understand is that it is an *emissive* panel rather than a *transmissive* one. In an *emissive* panel, each pixel is responsible for generating its own light. The advantage of this is that black pixels literally emit no light whatsoever, resulting in absolutely inky-black black levels that OLED is famous for. Plasma is also an emissive panel display technology, and it also had amazing inky blacks. The disadvantage of emissive panels is that each pixel will wear out at different rates from surrounding pixels depending on how hard those pixels are being used; as the pixel wears out, its light output diminishes. When you have uneven wear rates across the panel, with some pixels noticeably darker than others, that is what's known as burn-in. In a *transmissive* panel, there is an independent light source behind the panel called a *backlight*. The light form the backlight passes through the panel, and each pixel is designed to filter the light to generate the color it needs to be. All of these panels rely on LCD (liquid crystal display) technology for the pixels, but the backlight technology has changed greatly over the years, first using fluorescent lightbulbs, then moving to LED lights. What we call \"LED\", \"QLED\", \"xLED\", etc. are all variations of this theme. The advantage of transmissive panels is that individual pixels are not going to wear out, so you won't get the phenomenon known as burn-in. But that isn't to say the *TV* won't wear out, it's just that it's more likely that the *backlight* will wear out first before the pixels do. The disadvantage of transmissive panels is that the pixels can never really filter 100% of the light coming through the panel, so it is extremely difficult to get the inky-black black levels that you get with OLED. Manufacturers solve this problem by using *full array local dimming* whereby the backlight is divided into sections that can be controlled independently; if an area of the picture is dark, that section of the backlight can be dimmed or turned off resulting in better black levels in that area of the screen. The problem with this is that each backlight section is fairly large compared to the size of the pixels, so you can't control the brightness of each pixel as precisely as you can with OLED. Some manufacturers solve this by literally making the backlight into its own black and white LED panel, with as many \"sections\" are there are pixels in 1080p. And then there's Micro LED. This doesn't use OLEDs, it uses normal LEDs--the same as you would find in a LED lightbulb or traffic light--that have been shrunk down small enough to serve as individual pixels for a TV (hence the \"micro\" part). There's a limit to how small they can be shrunk however, so Micro LED TVs are typically massive, upwards of 100\" diagonal. It's an emissive panel, but the pixels don't wear down the same way OLED pixels do, so there's no threat of burn-in. I hope this helped!",
"Still rocking my Panasonic Viera ZT60. The pinnacle of both Panasonic and Pioneer's R & D on Plasma. It is truly a sight to see.",
"Well, if you are really five, I'll just say that OLED looks better but you are not allowed to use it to watch cartoons.",
"Liquid crystals respond to a charge to align into a polarizing filter. So you apply a charge, the element becomes a polarizing filter, and only allows light of a particular polarity through. Without the charge, the liquid crystal passively sits with a polarity that goes 90º. Line up a polarizing filter with another polarizing filter arranged to only let through light that's 90º polarized from the other, and the two filters will work together to block almost all light. So you can use a liquid crystal lattice, lined up perpendicular to a passive polarizing filter, with a regular polarizing filter to selectively let light through. Or In effect, each piece of liquid crystal is like a curtain you can open or close to let light through or not. An LCD display then is lit from behind with white light. For a black and white LCD display (fairly rare these days), imagine an grid of windows, each with a curtain either open and closed to let light through. You can electronically control each curtain, so that a picture can be seen in the windows, as viewed from very far away. Note that in order for you to be able to see anything, you still need light behind the windows/curtains. Each window/curtain is a pixel, and there is technology for letting in partial amounts of light through. So it can go from black to gray to white. The brightness of the darkest black compared to the brightest white is sometimes known as the \"contrast ratio,\" which helps describe just how much contrast the display can produce. For a color display, each window/curtain is actually a subpixel, that only lets through either red, green, or blue light. Just put some red, green, or blue film on the windows, and your window/curtain combination can start implementing color displays - block all blue, and the red and green will appear yellow. Block all green and blue, and half of the red, and it will appear to be a dark red. So LCD always needs to be backlit. The windows themselves don't create light, so you need some other light source behind the windows. It's much cheaper and easier to use one big light behind all the windows, than it is to put a different light in each window. LED backlit LCDs are better in many ways than some of the older technologies, because LED backlight is more even and more power efficient (which can make the whole display brighter). But there are LED technologies that are more about lining up a grid of little lights, each individually controlled, rather than the LCD technology of a grid of little windows, each letting through filtered light. LED is just a device that emits light in response to electrical current. Basically, OLEDs were the first emitters that could be controlled individually while being small enough to serve as pixels on a display. Traditional LEDs just weren't easy to manufacture small enough to incorporate as individual pixels. Note, though, that an array of lights that are individually controlled starts to give certain advantages over an array of windows/curtains. For power consumption, you're only lighting up the lights you use, rather than lighting up the whole screen and blocking it from going through at certain points. When you turn the light off, it's totally black (basically an infinite contrast ratio). On the other hand, there are disadvantages. Blue emitters tend to fade faster than green emitters, which tend to fade faster than red emitters. Emitters in general also just wear out, so you see pixels that are used too much start to burn out, which causes \"burn in\" on the appearance of the display. QLED display tech is actually an LCD tech, with windows and curtains, which is confusing enough. But the backlight actually goes through a fancy filter in each window, where a quantum dot technology glows a precise color that is different than the backlight. So it's not just a filter/curtain situation, but a combination of the backlight technology and a newer tech for emitting colored light. It combines some of the best of both worlds (but also suffers from that whole \"can't block out all light\" problem, so we're back to the contrast ratio issue). Some of the stuff they're working on is to have LED backlights that cover only a smaller portion of the screen, so that you can have pure black on one side of the screen (by turning off the backlight completely) while still using colors on another part of the screen. That super expensive Apple Pro monitor uses a lot of tricks like that in the background, with 576 individually controlled LED backlights."
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nhufhi | Why is the derivative of kinetic energy, momentum? ( reasoning without formulas if possible) | Physics | explainlikeimfive | {
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"The derivative of kinetic energy over time is power, i.e. the amount of energy spent or accumulated over a given period of time. The derivative of kinetic energy over speed is momentum, but that does not necessarily make some physical sense.",
"Momentum is what you get from a force applied over some time. Kinetic energy is work which is force applied over some distance. The derivative of kinetic energy with respect to velocity has units work/speed = force x distance/(distance/time) = force x time = momentum. Because the derivative is a gradient of a line on an graph in your head, then you can see at high speeds, the momentum is high, so the gradient of kinetic energy over speed is high, so small additions in speed raise the kinetic energy more than they would do at low speeds, where the momentum is low and the gradient of kinetic energy over speed is low. Physically speaking, adding momentum/speed to a slow/low momentum object adds less energy than adding the same momentum/speed to a fast/high momentum object. You can think of it as a fast object covering more ground over the time the force is applied, resulting in higher work, higher kinetic energy. In fact, it simply takes more energy to push a fast object than a slow object. This fact is exploited in the Oberth effect, aka the funny thing where rocket fuel gives the rocket more energy the faster it goes."
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nhuva8 | Why do pets recognize us in person, but not always over a video? | Biology | explainlikeimfive | {
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"Have you ever picked up a phone and known who you're talking to by recognizing their voice? Can you identify a handwritten note from your mother without the signature? Have you ever noticed a family member whose mannerisms or speech are identical to a parent? If you were blindfolded and walked into your grandmother's house would you instantly know where you are by the scent? Our pets perceive the world in a totally different way than we do. Their vision is different, their hearing is much better, their smell is much better, and the way their brains process these things and associate them is faster because it has to be as a survival tool. When you take away the most powerful identifier of smell, then you slightly change the identifier of sound by digitizing thru speakers, and finally even change the visual perception of a 3D person to a 2D screen, their whole world of how they know you, all of those subtle things that they know you by are missing or different. Now imagine that your pet is fighting against hundreds of years of survival instinct that something is wrong here; the image on the screen smells wrong, sounds wrong, and looks very different.. and that sometimes that takes a minute or two to process. But your pet loves you so much they're willing to ignore all of those instincts and interact with a screen because it looks like you, even if they don't understand the rest of it.",
"Pets will rely on smell, and if they look at electronic screens, their eyes will only see constant flickering, so they don't have any idea as to what theyre seeing"
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nhv02n | Why do larger animals have longer lifespans? | Small animals like hamsters only live 2-3 years (as pets) while animals like crocodiles live on average for 30 to 40 years. Is it because their bodies age or get weaker slower because they have a larger surface area or something? Thanks for answering | Biology | explainlikeimfive | {
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"It has to do with an evolutionary theory called K and R reproductive strategy. Larger animals (whales, elephants, humans, etc.) tend to have fewer offspring that live longer known as the \"quality over quantity\" approach. This is K strategy. Smaller animals (mice, ants, frogs, etc) tend to have far more offspring which tend to have short life spans known as the \"quantity over quality\" approach. This is R strategy. At some point, organisms realized in an evolutionary sense that their only chance at survival as a species was to adopt either a K or R strategy. This is also why larger animals (K strategy) tend to stay with their mothers longer. There aren't as many of them compared to smaller animals (R strategy) to keep the species going therefore they not only have naturally longer life spans but are also protected more in infancy when they are most vulnerable.",
"The logic doesn’t fully fit because some larger animals have shorter lifespans look at dog breeds",
"It is related broadly to resource efficiency. Larger animals need more resources (food, energy) to grow. This take more time. This means they spend more time being small (young) before growing into adulthood. This means their parents need to spend more time and their own resources taking care of their young. This means the parents cannot have many children in a short period of time. To make this all work out (ie the species to survive long term) the lives of the animal must be long. If the large species don't have long lifespan, most parents cannot raise sufficient children, the resources to have and raise kids are wasted and the species dies out. EDIT: left out a word.",
"Another factor to consider is the activity rate of the cells. Larger animal cells are slower and less active. They produce less heat and use less energy. Even their heart rate is much slower. A smaller animal is much more active. The cells produce more heat, they use more energy and their cells hence age faster. According to a study, mammals get 1 billion heartbeats per life time. So large animals with slower heart rate spread those out, and fast animals like the shrew (800-1000 beats/min) spend it up real quick.",
"Large mammal = slower metabolism & slower heart rate. Small mammal = faster metabolism & faster heart rate. I read an interesting tidbit from Stephen Jay Gould (in \"The Panda's Thumb, iirc) that if you look across all mammals, regardless of size, we each get approx 1 million heartbeats in our lifetime. The faster the heart rate, the shorter the lifespan. EDIT: Goulds approximation was a billion heartbeats, not a million."
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nhvaqs | How could a senior executive of a company sell any of that company's stock without it being insider trading? | Economics | explainlikeimfive | {
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"There are two primary ways: 1) They have transactions arranged to sell at pre-determined times well in advance, for example they want to sell $250k worth of shares on the last day of every quarter. 2) There are \"blackout\" periods where insiders are advised that they are not able to trade. These are typically at the end of a fiscal quarter when executives become aware of financial performance, or ad hoc when there is a material event being discussed like an acquisition. The company's legal department will advise those \"in the know\" when they can/can't sell because the executive meets the criteria of having \"material, non-public\" information about the company.",
"\"insider trading\" does not apply to any trade, it applies to trades based on \"inside information\" that the public does not have access to so if Tim Cook wants to buy a yacht and needs to free up $100 million in cash by selling some Apple stock, he can do that. Generally key executives need to file with the SEC before making large trades to that they are public knowledge in advance if Tim Cook knows that Apple is going to sink 10% because of a bad quarter, he CANNOT trade on that information before it is made public. And he can't tell his brother to trade on that information either",
"There are blackout dates when company employees cannot sell, like weeks leading up to earnings release, when a merger or acquisition is in the works, when material info like a lawsuit settlement or regulatory ruling are known but not yet publicly announced. Also, many senior execs set up automated trading orders, say selling 1000 shares on the Friday after earning release every quarter, which make it easier to show them at the trade wasn’t tied to any sort of inside knowledge."
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nhwy9r | How do singers make their voice jump up and down? | Most times when watching a singer perform the national anthem of a country on TV they will hold a note while their voice jumps. Is the singer doing this subconsciously or is this a skill learned with years of practice? | Biology | explainlikeimfive | {
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"It's called vibrato and it's learned. A modulated quivering voice is generally more pleasing (lots of exceptions to this) so good singers learn how to do it."
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nhx4jg | Why are wireless headphones the only implement you can't keep using while it's charging? | Everything else (unless it's something that moves like an electric car) can be used while charging. Phones, handheld consoles, game controllers, hair trimmers, flashlights, anything but headphones. Is there a reason for that? EDIT: typo | Technology | explainlikeimfive | {
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"Well with airpod style ones, the only feasible way to charge them is through wireless induction charging. I myself have a wireless headset that I can listen to while charging."
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nhx5fk | How do mosquitos fly in the rain? | How do they not get hit by rain drops? | Earth Science | explainlikeimfive | {
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"Mosquitos are so small and light that they get pushed out of the way by the air current raindrops produce while falling.",
"Mosquitos are often pushed out of the way by the air. Same reason it can be hard to smack them out of the air. But also, many insects just land while its raining. Finding a tree or something where they can hide out until it's over"
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nhxaud | Where do insects and flies go at night? | I could flip this by asking where mosquitoes go to during the day. Flies are disturbing me currently but they are gone before dawn. | Earth Science | explainlikeimfive | {
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"> Most insects are either active only during the day or only at night. When they're not active, they rest. This state of rest in insects is called torpor, and it's not exactly like sleep as we know it. During torpor, insects remain very still and don't respond much to stimuli around them. URL_0 ELI5: they sleep",
"I have always wondered about a variation of this. I don't see flys when I'm just outside minding my business, but if my dog takes a dump in the yard and I have to go in to grab a bag to pick it up, the shit is usually covered in flies within minutes...From where? and where they are from, how did they know there was a shit on the ground so fast?"
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nhxklx | How does someone with paralysis from the neck down continue to live, like why does their heart not just stop? | Biology | explainlikeimfive | {
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"The nerves that control most of your internal organs does not follow the same pathway as the nerves that are responsible for muscular control. Most importantly, they don't go through the spine so they can be perfectly unharmed as a result of spinal damage.",
"The heart specifically does not need any nerves to work. It’s self-controlling. The heart cells themselves generate a sort of a rolling signal which keeps the heart running no matter what. That’s one of the reasons you can’t consciously control your heart rate (unlike breathing).",
"The level of the spinal cord injury significantly affects the outcome. With very high cervical spinal cord injuries like C2, there may be no nerve impulses to the diaphragm for breathing. They also have no nerves to the intercostal muscles to allow for coughing which makes them very prone to infection. These people may be dependent on ventilators for the rest of their lives. People do better with lower cervical spinal cord injuries and may have some use of their arms and the ability to cough and breathe. The heart will beat but is affected by spinal cord injuries. Cervical spinal cord injury patients are prone to low heart rates. Some of the controls for things like blood pressure are also damaged. Spinal injury patients typically have low blood pressure. Other organs will work, but spinal cord injury patients are prone to developing severe constipation and the inability to empty their bladder. Rising blood pressures or heart rate may suggest problems like severe constipation or a very full bladder. Plus lots more...",
"Two reasons : The nerves giving the heart is rythm do not emerge from the spinal cord itself. They are part of the 12 facial nerve that originates from above the spinal cord, more specifically the brain stem. So even if you get a cervical injury, the brain stem will stay intact and so will those nerves. And secondly, your heart can life independantly to you. It doesn't (really) need your central nervous system to function, it is there to give orders for rythm regulation and adaptations but without it your heart will do just fine : it generates its own electric impulse in order to beat. That's why heart transplant function. We cannot reconnect the central nervous system to the heart so we live the heart beating alone and it works just fine. Your heart rate is just higher than normal (100 bpm vs 70) and it takes more time to get a heart rate rise during exercise because only the hormonal system can regulate the beatings now."
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nhypy8 | How do we know what things are thinking that can't convey that information? | Four instance, how do we know babies don't have object permanence or that butterflies retain memory of their life as a caterpillar. | Biology | explainlikeimfive | {
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"The experiment that proves that babies understand object permanence is as follows. Put a baby in front of a screen. Roll a ball from one side of the screen to the other, so that the baby can see the ball first disappearing behind the screen and then reappearing on the other side. Then track the baby’s eye movement. Turns out that most* babies past a certain age, when the ball has disappeared behind the screen, look towards the other side, where it should reappear in a few seconds. This is supposed to mean that they anticipate the ball appearing on the other side. Therefore they understand that the ball did not blink out of existence when it rolled out of their sight, that it’s still rolling behind that screen and should become visible again soon. With butterflies we can, for example, train the caterpillars to be afraid of something, and then see if the butterflies which used to be these caterpillars are afraid of the same thing which other butterflies aren’t afraid of. * “Most” means “more than if the babies just moved their eyes randomly”.",
"the easy answer is the scientific method. an idea is tested under strict conditions, and the results of those tests are analyzed. The results are then tested over and over again by different people, if all/most agree, then it is considered true. This can change with new studies and new perspectives but in general, if most of the studies say its true, most people will agree its true. For your example of object permanence in babies, conclusions are drawn from a baby's reaction to/lack of an object. For instance, You can gauge a child's understanding of object permanence by their reaction when you hide a favorite toy. If the child appears confused or upset and doesn't look for the toy, then they haven't yet grasped the concept. IF you repeat this test on multiple babies and they all show the same results, then it can be assumed that babe don't have object permanence."
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nhzont | why does our skin peel when we are recovering from sunburn? | Biology | explainlikeimfive | {
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"Well depending on the severity of the burn (mild - 1st Degree \\[no blisters\\] vs moderate 2nd degree \\[blisters\\]), the burn causes damage to the live cells below, the body reacts to damage by causing the blood vessels near the damage to become leaky which causes the area to feel painful and for this question, allows fluids from the blood vessels to fill the area (along with cells to repair) causing swelling. That swelling causes layers of the skin to separate, with 1st-degree burns this swelling is relatively mild, with 2nd degree burns the swelling is more intense hence blistering (kinda). Either way, as the area begins to heal the fluid is reabsorbed by the blood vessels, now leaving a \"space\" between the \"live\" skin and the separated (dead) skin which over time sloughs off, which we know as peeling."
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ni0eyb | Why can pets recognize you through the window but not usually over a computer or phone screen? | Other | explainlikeimfive | {
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"text": [
"It's your scent. Plus they recognize scents and sounds associated with you and your arrival."
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ni0how | How are software update numbers assigned, for example version 22.13.001 vs 22.14.001 vs 23.01.001... what would be required to change one number vs the others? | Edit: Also forgot to include in a scenario where you have 22.13.002 vs all the others | Technology | explainlikeimfive | {
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"Different companies and different projects have different rules about when numbers change, how many numbers to use, etc. But in general, the more serious the changes in the software, you increment a number further to the left and all the numbers to the right become 0 or disappear, again depending on policy. What qualifies as a \"serious\" change is again a company policy. When chrome or firefox increment the left-most number they've added or removed something that users WILL notice, at least eventually if they use all the features and browse all the settings, etc. For minor changes - spelling corrections, bugs fixed that most users will not notice - you increment a number further to the right. 1.2.3.4 might become 1.2.3.5, or maybe 1.2.4.0. Software used by other software often uses version numbers to show the difficulty of upgrading. If their policy says that the middle digit changing does not mean work for its users, then upgrading from 2.4.5 to 2.5.6 should be safe because the left digit remains the same. But once again, every company has its own rules and this is just the trend. There are software projects that increments a number just because the number to the right got too big Linux went from 4.20 to 5.0 just because its lead developer thought `20` was a big number. There was nothing unique between 4.20 and 5.0 when compared to 5.0 to 5.1, or 4.19 to 4.20.",
"No hard and fast rule. The \"small\" numbers (ie to the right) are typically assigned to bug fixes, minor corrections - eg spelling errors, window size corrections etc The \"middle\" numbers are for minor content tweaks. For games, these are things that affect gameplay but in not a major way (like adjusting a character power, speed etc). Sometimes releasing new content. Typically these changes are fairly seamless 22.001 will work with 22.002 etc etc. The \"major\" rev numbers (ie to the left) are usually major changes to the software. It will probably have significant impact to the user. Usually not done very frequently - for stable software, it could be years. The major revs can also introduce incompatibility. So rev 22 might not work with rev 23.",
"The number is up to the developer and different developer change them in different way. A common way is the X.Y.Z variant. X is the major version number. Y in the minor version number. Z is the patch. So X changes when you consider is major changes. It might be that non backwards compatible charges, other major chages or just that you do that because you charge for uppdates to new major version. Y change when you do minor changes to the software. Z changes when you fix bugs or similar small changes. But that is just a common way to do it. As a developer you can do it anyway you like. You could release software and decrease the number start at 100 and next version is 99. It might be stupid thing to do and it confuse people that use it but you could do it There can be requirement of what to do if you use some external services like app stores to distribute the software so updates etc works"
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ni0qa9 | Why do our brains record cringy/painful moments in our lives better than moments we truly enjoyed? | Biology | explainlikeimfive | {
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"That's learning. At a basic level. Your brain learned that certain things cause uncomfortable reactions in order to avoid them in the future. So you're constantly reminded about something embarrassing so that you can avoid doing it again.",
"memories are strongly connected to emotions. The stronger the emotion of the event, the better the memory of that event will be. Furthermore, in general, negative emotions are felt stronger than positive ones.",
"Humans, being the weak, slow, sensitive creatures we are compared to nature/other animals, evolved to develop a very strong amygdala/trauma center. Additionally, we developed a strong social-reliability sense. After thousands of years, our brain has decided that if we aren’t social warriors afraid of tripping over the same rock twice, we literally won’t survive. This created a prioritization of these memories so that we can learn from them. Otherwise, our friend getting eaten by a lion might happen to us as well, or if you don’t learn to fit in with the group, you’ll get stranded and not being to gather enough food/water to survive."
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ni2rp5 | What is the absolute minimum calorie intake for an average human, if they want to survive on very low supply of food? | Also considering they have fat and muscle mass to turn into energy. | Biology | explainlikeimfive | {
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"It depend on the person and time you need to survive, The minimum you can survive on is zero food intake. You can survive with no food for a couple of weeks. If you eat some food but not enough you can survive for longer If you like to survive and do not use you body for food the answer will depend on the person. A rule of thumb is 2500 Calories for men and 2000 calories for women because men tend to be larger. It will be less for a child. That will also depend on you activity and even the temperature of the environment. If it is to cold you will need to use more food to stay warm."
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ni3wps | Why do wind and rain generally accompany one another? | Is it through causation or correlation? Does rain cooling the air cause wind? Does wind moving clouds cause rain? | Earth Science | explainlikeimfive | {
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"It's both cause and effect. Wind can happen where there is low pressure next to high pressure and the high pressure air rushes in to fill the low pressure. This is also the exact place rain happens. Then also wind happens when temperature differences make a lot of hot rising air and cold falling air move around. And dumping a bunch of water on something is a good way to make it change temperature fast."
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ni475k | Selective reuptake | Is "selective reuptake" a natural process that happens normally, or is it a dysfunction? I know about things like SSRIs, but never could figure out if selective reuptake only happened when there's a problem. | Biology | explainlikeimfive | {
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"Reuptake is normal process, but selective inhibition is the process by which SSRIs work, it's neither a dysfunction nor a normal process, it's the SSRI changing a normal process. Neurotransmitters do their work when they're in the gap between neurons called a \"cleft\". Once they did their jobs, they get taken back into the neuron that let them out. That's the process of reuptake. SSRIs are called \"selective\" because they \\*selectively\\* block the reuptake of only serotonin and not other neurotransmitters as opposed to older antidepressants which blocked the reuptake of a bunch of different neurotransmitters. Think of SSRIs like a bouncer at a club where the club is your brain cell. Each neurotransmitter has its own door that only it can go in through (I.e. serotonin can only go in through its door, not the dopamine door). The bouncers at the norepinephrine and dopamine doors let those neurotransmitters in, but the bouncer at the serotonin door doesn't let the serotonin in.",
"Selective reuptake is actually natural process, but that nomenclature is not used in the field of biochemistry or neuroscience to describe normal functioning of receptors because it would be confusing as it is a description used to describe how psychoactive substances / medications work (i.e. SSRIs) An example of natural selective re-/uptake is how a plethora of pumps and transport proteins work on a cellular level. The brain chemical, or neurotransmitter, **serotonin** is used by brain cells to communicate with other cells. The natural serotonin transporter (also known as SERT) functions precisely as a selective reuptake transporter in these cells. Serotonin that is released outside of nerve cells in your brain to communicate with other nearby cells, is subsequently recycled back into the originating cell by SERT. In this way, SERT acts **selectively** (i.e. it specifically pumps serotonin, as opposed to other neurotransmitters like dopamine) and performs **reuptake** (i.e. it pumps the chemical back into the storage chambers of the cell that released it, once the job is done). This is a ubiquitous concept in biochemistry and cell biology but again, the nomenclature used often varies widely. Reuptake should not, on its own, be thought of a dysfunctional process. Instead, when considering a condition like depression where SSRI drugs are used to \"block serotonin reuptake\", one has to consider a bigger picture. The leading hypothesis in medical science is that in depression, the chemical signaling of serotonin between brain cells is not working properly -- either there is not enough serotonin released or the serotonin released is pumped back too quickly -- serotonin effects are lower than they should be. SSRI drugs block some of the \"reuptake\" transporters like SERT from functioning, allowing a net increase in serotonin's chemical effects on neighboring brain cells in both duration and intensity. (Disclaimer, the medical and scientific understanding of how depression results from \"chemical imbalance\" in this regard is still somewhat controversial, and the process I described above is **a lot more complicated** \\-- but for the purposes of answering your question these examples hold true). Hopefully this helps answer your question in a simplified but informative way. FYI: I am a medical doctor and also have a bachelors degree in biochemistry"
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ni6sf5 | Why do people say a metric ton to mean super heavy, even though a metric ton is less than an imperial tonne? | Other | explainlikeimfive | {
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"In that sense, \"metric\" is acting like an [intensifier]( URL_0 ). It's like saying a \"shit ton\" - here, \"shit\" doesn't *mean* anything. It's not a literal ton of excrement, and \"shit\" isn't any kind of measurement. It's just a word to make it *feel* more emotional, more significant. For what it's worth, I usually hear it used in combination with an actual expletive, as in \"a *metric* shit-ton.\" The specificity is added ironically to further emphasize the ridiculousness of the weight or amount of the thing. It's like, \"I very carefully measured this thing and I found it to be almost exactly a metric *shit-ton* of stuff.\"",
"Personal usage: Metric shit-tonne Imperial fuck-ton. The actual weights are nearly interchangeable in international markets, though varying exchange rates do cause fluctuations.",
"Humorous answer \"because not even 3rd world countries use imperial\" Actual answer? Likely because metric is the standard for most of the world. It also sounds better when used; \"this must weigh an imperial ton!\" vs \"that thing weighed a metric tonne!\" Edit: incorrect word usage"
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ni76k3 | Why does meth make your teeth rot? | How does meth mouth occur? | Chemistry | explainlikeimfive | {
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"Several reasons 1. Methamphetamine's actions in the nervous system inhibits the production of saliva from the salivary glands, and chemicals in your saliva help protect your teeth from bacteria that cause tooth decay. This effect lasts much longer than the high/euphoria one gets from meth. 2. Another nervous system side effect of methamphetamine is bruxism, or teeth grinding/clenching (similar to what happens to users of MDMA/ecstasy). Excessive and prolonged grinding and clenching of teeth wears away tooth enamel making them more susceptible to the bacteria that cause tooth decay like in problem #1. 3. The smoke from smoking methamphetamine contains various corrosive compounds that directly wear down tooth enamel, damages the gums which exposes less protected parts of teeth, and can block salivary glands from releasing what little saliva they are producing from the effects of the meth itself, all of which further compounds problems #1 and 2. 4. Chronic methamphetamine use, like many addictive drugs, causes behavioral changes that often lead to less attention paid to personal hygiene...i.e. brushing teeth regularly. Again compounding problems #1 and #2. The sum of these reasons together lead to \"meth mouth\" but the meth itself doesn't exert any effect on the teeth. Good oral hygiene and use of saliva-promoting mouth washes can largely mitigate the problem. A bite blocker or even a \"pacifier\"/teething-like device you give to babies can prevent the damage from tooth grinding too."
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ni7q0d | Why do we physically laugh and make different sounds according to our level of amusement? | Biology | explainlikeimfive | {
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"In evolutionary terms, laughter is sometimes referred to as a play signal. It's a way of saying \"everything's fine, I'm not hurt, I'm not going to hurt you,\" or \"I am having fun, there is no danger here and no reason to stop.\" [rats laugh]( URL_0 ) when they are tickled and when they wrestle/play with other rats (their laughter is inaudible to humans). When they are scared or in danger, they make different sounds, just like we do. [Jaak Panksepp]( URL_1 ) spent basically his whole life studying neuroscience and was the first to discover laughter in rats. It turns out laughter is hardwired somewhere deep in our brains! It seems researchers disagree on exactly why that is, but one theory is that it has much to do with the very important development of \"social skills.\""
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ni7xzs | Why is a negative times a negative positive? | Mathematics | explainlikeimfive | {
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"text": [
"When you multiply by a negative number you are removing a number that many times whereas when you multiply by a positive number you are adding it that many times. If you multiply -2 by -2 you removed two debts of 2 which means you are owed 4 (a positive number)",
"Actual ELI5: Negatives are like UNO reverse cards. Reversing a reversal puts you back in the original direction. Your logic makes sense for addition (where negatives just \"pile on\"), but multiplying by a negative is more like a reversal: take whatever you have and negate it."
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ni883s | Why do people buy nfts? I dont get it. | Technology | explainlikeimfive | {
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"I am very much just as puzzled at this whole hype as you are. However, the fact that there are copies of the video all over the net isn't a good argument, imho. You can get prints (copies) of the Mona Lisa all day long, it's still a different matter to actually *own* the painting. I know that this is not a perfect analogy because if you own the Mona Lisa, you have an actual physical thing you can touch. Still, this is about owning the original."
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ni9l6g | How does pausing in video games work? | What happens when you pause a game? Why are you able to just stop all the work the computer is doing and perfectly able to let it go again? With all the calculations it's doing, especially for 3D games, surely pausing it can mess up something that's in the middle of running. | Technology | explainlikeimfive | {
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"> With all the calculations it's doing, especially for 3D games, surely pausing it can mess up something that's in the middle of running. Why would it? You also can put down your pencil at any point when doing math on a piece of paper and then resume at any time. Same applies to computers. Fun fact: your computer is actually switching programs it is running at hundreds of times a second, pausing every time to run something else. It will run one program for one hundredth of a second, pause that computation and run another program for another hundredth of a second, and so on to make it seem that all your apps are running at the same time.",
"Games run in a loop: 1. Update game state (e.g. enemy positions, camera angles, etc) 2. Re-draw the screen 3. Go to 1. Typically when you pause a game, the game state is stored in memory but this loop is paused. Nothing is being updated. When you resume the game, it continues the loop with whatever state it had before it was paused.",
"You are not stopping the game. The game is still running. When you pause a game you just tell the AI to stand still and not do anything until you want it to resume. The game is still running. Its just that all the characters are not doing anything. It would be far too much hassle to shit everything down when you just want to pause."
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niadug | -How do sounds retain their individuality even when there are a lot of them? (like identifying specific sounds in public) | Physics | explainlikeimfive | {
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"Physicist/Hearing Scientist here. I think the question you're asking is how come sounds can be added together in the air, but then they can be broken apart by our brains. Yes? So, when two sounds meet, they interfere with each other. They can add together if their peaks align, or they can subtract if the peak of one meets the trough of another. But most of the time, they combine to form some complicated squiggle. The thing is, this squiggle can alway be broken down in to a bunch of simple sine waves. Mathematically, this is achieved through a process called Fourier Analysis. Basically any squiggle (or at last any squiggle that the air can carry) can be split in to a number of pure sine waves (which is the kind of stereotypical wave shape). Our ears are really good at this breakdown too. Inside out ears, past the eardrum and some bones, is an organ called the *cochlea*. It's a small shell-shaped thing, and contains a stretched strip called the basilar membrane. When sounds hit this membrane, it wobbles up and down as the sounds travel along it. But, because reasons (the shape of the membrane and physics of impedance etc., doesn't matter), different sounds can travel different distances along it. Specifically, high pitched sounds can only travel a short distance, but low (bass) sounds can travel further. When these waves stop, they cause a signal to get sent to the brain thanks to a bunch of 'hair cells' (they're not really hairs but they look like them up close) in something called the *Organ or Corti*. Point is, the mix of sounds that enters your ear gets broken up by physics into all the different pitches of simple sounds. From that point on, it's a case of your brain being a ridiculously good computer, and managing to piece back together which pitches came from certain sources so we can work out what all the different things we are hearing are and where.",
"Because our brains have been using sound for a long time. By using the delay time between a sound reaching our ears in conjunction with the shape of our ears we can establish a direction and distance from the source without ever having to consciously decide to do so. We can do this for a huge number of simultaneous sounds because we can tell where each sound started. As a neat aside, we can also hear the difference between hot and cold running water, and how full a vessel is. Loops back to the same point however, we've evolved a very strong skillset revolving around our ears because we've had them much longer than we've been human.",
"If you mean the cocktail party effect, Wikipedia does a pretty good job explaining. At least, much better than I could do. My two cents: URL_0 Probably another redditor can ELI5, but this is a starting point.",
"Waves are super interesting! So most people seem to think your question is this: \"How do our ears understand specific sounds when there are multiple sources of noise?\" But I'm pretty sure what you are asking is: \"If sound is vibrating air molecules bumping into each other, why don't different sounds 'bump' into each other and become distorted and messed up immediately, or very quickly?\" So I'm not yet an expert on waves, but I have studied them a little bit and plan on doing more in the future, but waves are weird. So a wave carries a certain amount of energy with it. An electronic speaker has a sort of cone-shaped membrane and electrical signals (often coils and magnets) make the membrane vibrate with enough force to \"push-pull\" the air in front of it. If you tried doing that slowly it's not going to make a sound, because there wasn't enough energy for it to make a wave. But I think this energy threshold for starting a wave is important. So once a wave begins (we say it \"propagates\" when it \"moves\") it carries some kind of information. In the case of sound waves, it carries some energy (simply put: the \"loudness\") and the different frequencies. Different voices, different instruments, and everything else have many tiny differences in those frequencies due to shapes of bodies and materials and all kinds of other things. If you played different sounds from two speakers that were aimed diagonally towards each other (so their aim should cross), their sounds *will* interfere with each other. But because of the amount of energy contained in the initial sound signal - which decays over time - and perhaps other interesting properties of waves (which I'll try to get into below) they don't break down quickly and they don't interfere as much as solid objects interfere with each other. Think of two billiard (\"pool\") balls on a table and roll them across the table from one end to the other longways so that they barely touch in the middle. They'll both roll along the table longways the entire time, but when they bump they slightly change direction. They have a *momentum* and if their original direction was left-to-right, their bounce doesn't stop moving left-to-right, but it does change their motion slightly. But waves are even more interesting! Because sound waves aren't made of one solid object moving across space (like the billiard balls) they are actually the transfer of vibrations across air molecules, they can pass against and through each other even more easily than the billiard balls. It's really a *transfer of energy* and not specific air molecules moving from point A to point B. Water waves are not very different at all. If you've ever swam in the ocean, you may have noticed that waves don't really \"push\" you, they just \"bob\" you up and down. That's because the water isn't really moving much in the direction that we see the wave move. The wave is the collective transfer of that energy from one place to another, but it isn't water all moving towards the beach. So waves *do* interact with each other, and decay over time, and can cause interference! But not as easily as solid objects do! This may have been a little bit higher than ELI5 but waves are hard! Hope this helps a bit!",
"Imagine a really big wave. If you throw something in it - it will still produce smaller waves - in this big wave. Then when waves are overlapping each other they create different interferences. When 2 “highs” meet - they create a bigger “high” - and vice versa. As long there are enough differences between them and/or differences/similarities are working together/against each other creating patterns - we can decode things. Our brains are crazy good at this because our lives depended on it throughout evolution. Additionally- that’s why we are best at decoding sound in the range of roughly around 1kHz to 5kHz - it’s where our own speech is located."
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nic0fe | How can companies use Crytpo to sell items when the crypto value changes every second? | Economics | explainlikeimfive | {
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"The price of the item varies depending on when you buy it A guy paid 10,000 btc for 2 pizzas once.",
"Every currency changes a little every day and often several times a day. When you buy something a conversion is done according to the current value of the currency you are paying with.",
"Theoretically, a business can exchange their goods and services for anything they want, cash just tends to be more convenient. The decision to accept payment in crypto is similar to accepting payment in another country’s currency. For example, an airline in the UK might let American customers pay in dollars. It’s possible that the exchange rate between the British pound and US dollar will change before they convert the dollars to pounds, but the change is unlikely to be significant. With cryptocurrencies, the exchange rates often fluctuate more dramatically, but the concept is the same.",
"What you just described is exactly why more companies are bailing on it. It's incredibly volatile... but big companies knew it's still profitable. That volatility vs upfront value is the back and forth you and they are debating.",
"You agree to a specific price (standard currency converted to crypto) for a certain amount of time. The price often is a bit higher to help pay for the certainty of that agreed upon price. It may also include a commission for the exchange or provider that accepts the payment for the company or store.",
"The merchant is usually accepting a immediate conversion from crypto to their national currency at the point of purchase. If they are not then they become market speculators hoping that the crypto they accept will become more valuable with time.",
"The same happens for any trade using different currencies, not just crypto. It becomes stable if a company spends money and sells using the same currency. & #x200B; If you are refering to Musk's \"buy tesla in btc\"and its recent change of mind \"actually no you cant\" , you need to put that in context. They bought tons of BTC cheap before saying that, and probably have sold them all before saying people could not use them, so they can buy them again after pushing the price low. This is a classic pump and dump scheme, except it has been done by someone with enough power to not get annoyed by the SEC.",
"A company will sell something based on the value of the currency at the moment you make the agreement. So a customer will say 'i would like to buy this now and pay in crypto', the store will then look up the value of crypto at that point, and charge the customer the appropriate amount of crypto equivalent to the selling price in dollars. The fact that crypto varies quite so much is why relatively few companies will accept it - it is too volatile, and too much of a gamble. 1 BTC is currently about $36k, so you could go and buy a $36k car for 1 BTC. The problem is that if tomorrow the value of bitcoin rises to $40k, you have spent $4k more than you needed to, and the dealer has gained $4k extra. But equally the value could drop to $32k, and the dealer loses $4k while you effectively got your car for $4k cheaper. Some companies are willing to take a gamble on this and see it as a way to potentially earn a lot of money, but it could also make a huge loss if the crypto bubble bursts. There is the story that back in the early days of bitcoin when they were very easy to mine and basically worthless, of the person who bought two pizzas for 10,000 BTC - at the time a brilliant deal, since he had probably spent pennies on mining them himself. Those two pizzas would now be worth $340,000,000 had he kept hold of the bitcoins instead... Whoever he bought the pizza from however took a gamble that bitcoin would ever be worth something and made quite a big profit (or probably spent them on something else at the time for an equivalent exchange rate)."
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nic54z | Why the birds are not singing when it is raining? | The title says it. | Biology | explainlikeimfive | {
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"Birds sing for several reasons. 1) To attract a mate. 2) To warn of danger. 3) To communicate food sources. 4) To claim territory. Birds tend to take shelter during the rain and avoid flying as it becomes dangerous. This means they are not going to actively be seeking food, seeking a mate, or defending territory during a rain storm. They may warn of predators but predators are also taking shelter from the rain so rarely hunting them. As such there is no drive for them to waste energy singing when there is no use for it."
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nid9az | How exactly do two gasses (Hydrogen and Oxygen) make a liquid when they are together? | Just that really, I don’t understand how two gasses can combine together and suddenly their a liquid...which can then be frozen into a solid. So is ice really just frozen gas? And if I had a vacuum chamber and started filling it with 2 parts Hydrogen and 1 part Oxygen, would water just suddenly appear? Like I understand it forms a molecule and all because the oxygen has two open slots in its outer layer which the two hydrogen atoms conveniently fill. But aren’t those still two gases, just together? All in all, liquids confuse me. | Chemistry | explainlikeimfive | {
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"A molecule is not required to share any characteristics whatsoever with the atoms it's made up from. That's why we can take sodium, which is a soft metal that spontaneously burns when dropped in water, and chlorine, a toxic green gas, combine them together, and get a delicious white crystalline solid (aka common salt). As for the combination of the gasses, no, oxygen and hydrogen won't spontaneously condense into water if you mix them together. You need something to spark the reaction--literally, in this case; a spark or flame will heat the gas mixture enough to start the reaction going, and since the reaction is exothermic (produces heat) then it will keep going once started until all reactants are consumed. The practical upshot of this is, if you have hydrogen and oxygen mixed together in their ideal 2:1 ratio and you apply a spark, the whole lot will blow up in your face producing hot water (e.g. steam) as the product.",
"Hydrogen and oxygen aren't gases. They're elements. Elements, like all matter, can be solid, liquid, gas, or multiple other phases of matter depending on how much energy the molecules have. The properties of the molecule are different from the properties of the individual atoms, and those properties determine how they molecules bond, what density they'll have, things like that which go into determining what the boiling point of that substance is going to be. So, for hydrogen and oxygen individually, that boiling point is very very low. That's why they're gases at even very low temperatures. But water has a boiling point of 100 Celsius, or 212 Fahrenheit, so it's a liquid at temperatures below that, and a solid at temperatures below 0 c/32 f.",
"My attempt at actual ELI5 When hydrogen is by itself, it isn't attracted to other hydrogen. So the hydrogens can fly away from each other easily at room temperature, making them a gas. The same is for oxygen. When oxygen and hydrogen are reacted together (look up hydrogen balloons for what this looks like, kaboom!) the oxygen and hydrogen form a weird V shape where one side is positive and one is negative (similar to a magnet, opposites attract) Because the water molecule (hydrogen and oxygen together) has a positive and negative side, they attract each other. (like magnets!) so they can't fly away from each other easily. Meaning it is not a gas unless heated A Lot! To answer the gas chamber question. Water wouldn't appear, unless you do something to make them react. If you light a fire the hydrogen will react with the oxygen. KABOOM! It will create an explosion with water being left over.",
"If you stick enough lego pieces together in the right shapes, they stop being a pile and start being the thing you're building out of them.",
"Water molecule should be a gas, as similar light oxides (CO2, NO2, etc.) but hydrogen, even when joined to its oxygen atom, gets attracted to oxygen atoms nearby (from other water molecules). These hydrogen bonds, are not as strong as those inside the molecule, but strong enough to retain them together: they form now a liquid. Edit: hydrogen BONDS.",
"Hydrogen and oxygen are not gases. They are elements. Elements are counted by atoms. Hydrogen gas is 2 hydrogen atoms stuck together. Oxygen gas is 2 oxygen atoms stuck together. If you combine oxygen gas and hydrogen gas, you'll still have gas. But if you add some energy, say from a match, the gases will break. Those atoms will seperate, release a bunch more energy, and most will recombine to form water.",
"> So is ice really just frozen gas? Yes All solid things are just frozen gas, and all gases are just gaseous solids. Solid water is ice, liquid water is water, gaseous water is steam.",
"You have a lot to learn about chemistry. Nothing on the periodic table is a Gas, solid or liquid. Basically hydrogen and oxygen combined using a catalyst creats a polar molecule that is attracted to other h2o molecules. They stick together. Think about it. You can have liquid hydrogen and oxygen at very low temperatures and under pressure. Both can be solids at extreme temperatures. Nitrogen at room temp is a gas. Cool it down enough and you have a liquid."
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nidhgx | What are those holographic stickers on stuff like books and boxes? How do they work? | Physics | explainlikeimfive | {
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"They work because they have a pattern of very fine lines pressed into their rear surface. The lines are small and close enough that they interfere with the individual waves of light, cancelling and reinforcing different colours depending on the angle. They are used because they used to be expensive and special, now they are almost free to produce, but do look complex."
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niez43 | Rayleigh Scattering | Physics | explainlikeimfive | {
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"In one sentence: Rayleigh Scattering is when light bounces off small particles. There is of course a lot more to this but I’m going to assume you mean with respect to everyday things like the sky being blue and the sun being yellow. It wouldn’t have hurt to elaborate a bit more in your question. Our atmosphere has particles of dust which are there naturally or form pollution. The size of these particles is just right for interacting with visible light coming from the sun, which contains all the colours of the rainbow. Because of physics (keeping it ELI5) it so happens that higher frequencies such as blue light are way way more strongly scattered than low frequency waves such as red light. The consequence of this is that the sun looks yellow because blue light is scattered *away* from us, and the sky is blue because we’re looking at that scattered light.",
"May I interest you in a physics lecture about rayleigh scattering by that is very much ELI5 [ URL_0 ]( URL_0 ) it also includes a demonstration with smoke and colours :)"
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niffp1 | - Does the newly added Us inflation give to me (a European) more power to buy products from the us? | Economics | explainlikeimfive | {
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"No because the Euro can also inflate/deflate. It means that if you are a producer of goods or services, you can now sell those goods or services to the US for more money than before. Inflation rate is pegged to the prices of goods and services. Foreign exchange rates are tracked separately.",
"Probably not - there's been a very slight increase in the value of 1 Euro compared to the dollar, but recent price increases in the US aren't driven by an increase in the money supply (which would result in cheaper dollars for a consumer who has euros) but by a jump in gas prices, from increasing demand as commuting picks up again."
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nifnxn | Why does babies eyecolor often change as they grow up? | Biology | explainlikeimfive | {
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"So melanin here is what's to blame. This is what basically says what our skin/eye color will be and in babies both skin and eye color take a bit to get to the finish line. For skin it develops quite quicker (Can take up to 6 months) but for eyes it usually is expected at 9 months of age, but can take as long as three years. EDIT: cleaned comment up"
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nifpml | What happens to all the plastic that people collect on clean up drives from beaches, forests etc.? | I was watching John Oliver's segment on plastics where he explains how most plastics are either not recyclable or not recycled due to economic reasons. So when people collect things for clean ups, what happens to it eventually? doesn't it still end up in some dump or something? | Other | explainlikeimfive | {
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"\" doesn't it still end up in some dump or something?\" It does, the problem is (in general), that it didn't end up in a dump the first time. It started it's life as litter tossed in roads (with drains to the lake/ocean), litter on the beach, litter tossed off the side of a boat, garbage blowing off a barge or, in some of the biggest cases, shipping containers falling off of cargo boats. The vast majority of garbage that goes to a landfill will stay in a landfill. The majority of plastic you find on a beach wasn't in a landfill to begin with.",
"Multiple things can happen, I do personal litter picks and take part in drives from time to time: * Binned - for landfill (or burnt for energy) * Binned - for recycling (only clean items with a high recycling rate) Sometimes it is used for art installations or other activities first, but ultimately the bin. It is often counted first so that figures for most found item on the beach are pulled together."
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nig8h4 | how and why does stress affect body functions? | Biology | explainlikeimfive | {
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"It releases the stress hormone known as cortisol. This hormone in an unbalanced state (aka high induces stress environments) can cause high blood pressure, rapid weight gain/loss, muscle weakness, and most important mood swings. Mood swings being the topic of most importance, in my opinion, will do the most damage to the body because these feelings will lead to further emotional and or physical harm. These mood swings could likely show as anxiety and/or depression which have been know to ruin lives, love, and careers."
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nii0dr | How does cash betting work, like they do in the movies. | In the movies, when theres a fight or a game etc, sometimes there is a crowd of people frantically waving money and one guy is collecting it. The only example I can think of right now is in Hot Shots 2, the fight scene in the beginning. The "judge" guy starts the fight before he proceeds to collect money from the cheering crowd. Ive seen that kind of betting in other movies. But how does that kind of betting work? How is there any oversight over who bet with what against who? | Economics | explainlikeimfive | {
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"If the scene is filmed accurately you will see the people collecting money also have a small pad and pencil writing down info. When you first walk in you would be given a number or code like at an auction. So he would write real fast something like 21-$100/blue (or whatever they wanted to use to identify the fighters. In most movies being more accurate would also slow down the action so its usually not shown correctly. It just wouldnt be as exciting to see the fighters standing there for 10 min while they collect all the info and money.",
"When they say 2 to 1 odds for Red. It means if you give $100 dollars and you bet that Red fighter is going to lose and he loses you will get $200 dollars. Basically they bet that their fighter (or some fighter) is better and stronger than the opponent and they offer to double or triple your money if they are wrong. All you need to do is accept the bet and put down some money. Now in reality they quickly write down that info on small paper and give it to you like a receipt and proof you paid money and made a bet so that if you win you can show it and collect your money. That is how they keep track of how much people bet and how much they earned/lost.",
"There isn't much oversight except the bit where *\"We will beat the living shit out of you if you don't pay out to the winner.\"* You need to remember who put down money on who, so that you can pay out to those who betted on the right winner at the end. Either make good notes or have a veeeeeery reliable memory.",
"It depends - there are types of betting. Parimutuel is where you bet against everyone else in the pool, like in horse racing. After all bets are in, payout is calculated based on who bet for which outcome, and the odds change up until the event starts. The house makes money by just taking a small percentage of the overall pot before payout. Other is fixed odds, where you aren’t betting against the others but against the house. The house just sets the odds so that it can recover over long periods of time and a lot of different bets. There are variations and a their methods too, and a lot of nuance."
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niik90 | How do paleontologists discover underground cities and fossils? | Technology | explainlikeimfive | {
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"Detective work really. We know fossils form under very specific conditions. Essentially an organism needs to get covered up somehow before it's eaten or decomposes. While the soil around it petrifies. Water seeping through will slowly erode the organism away while depositing minerals that fill up the organism shaped hollow that's left behind. The study of geology also teaches us what the Earth was during different time periods. That helps us look for rock formations from the right time periods. But more than that, we can also look for places that used to be conducive to the creation of fossils hundreds of millions of years ago. For example, there are many English beaches that are great for fossil hunting. The tall cliffs lining the beaches are essentially layers of sediment from across the ages. Every time there's a storm, another layer erodes from the cliff side, potentially exposing new fossils. Other fossil fields used to be a bend in the river at some point in time. Animals would die in or by the river, get swept away by the water and get stuck in the bend while getting covered up by mud. Anyway, there are lots of different indicators. But palaeontologists start by trying to find areas of the correct age with features that indicate that past conditions were perfect for fossils. Of course, there's also a lot of fossils that were found through sheer luck. For instance during mining excavations or during construction work. Human structures and artefacts are searched for by archaeologists, not palaeontologists. But the process is kind of similar. It's detective work to identify the most likely locations. Human habitation leaves signs even long after it's gone or buried. Vegetation grows differently if there's stone underneath rather than pure soil. Or buried ruins can cause unnatural-looking hills or shapes in the landscape. Human habitation is also predictable. We need water. We need land that can support us. We build roads that affect the landscape long after they're buried and so on. So just like the geological history of the land can teach us the most likely places to look for fossils, it can also teach us how humans from the past would have looked at the land to find the best places to settle.",
"Archeologists discover cities, paleontologists discover fossils. Different people, different training, some of the same techniques."
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niirw4 | How does a children's spring microphone work? | Here's a link to a diagram ([ URL_2 ]( URL_2 )) and a picture of the microphone itself ([ URL_0 d=2ahUKEwjCtNGls93wAhWQBisKHdRABGMQ2-cCegQIABAA & oq=how+does+children%27s+spring+microphone+work & gs\_lcp=CgNpbWcQA1CWHlj1JmCMKWgAcAB4AIAB-AGIAZIJkgEFMC42LjGYAQCgAQGqAQtnd3Mtd2l6LWltZ8ABAQ & sclient=img & ei=5AepYMKyNpCNrAHUgZGYBg & bih=625 & biw=1366 & rlz=1C1CHBF\_enAU877AU877#imgrc=iNfmh01cUYJzjM]( URL_0 | Technology | explainlikeimfive | {
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"text": [
"You may have heard that LEDs can also be used as light sensors, or the reverse. We make these devices separately, because we optimize them for one function or the other, but each type of component can be used the other way if the need arises. Speakers and microphones are another pair of devices that can be swapped when needed. Speakers work by vibrating a diaphragm according to some signal, while microphones generate a signal using the vibrations of a diaphragm as a sensor. As long as you have some way to power them both, you could plug one straight into the other to create a device that carries sound from a microphone to a speaker (though the speaker would be very quiet; usually you at least want to add an amplifier onto the circuit). The fun thing about speakers and microphones, though, is that you can power them with things other than electricity. The two-can telephone is an example of this: tie two cans together with a string attached to the bottom of each, stretch the string tight, and sound will travel between the cans. The tension in the string allows it to vibrate along with the cans, and this essentially carries a signal across. All of the above is leading up to the spring microphone, which takes this principle and applies it using a single diaphragm as both speaker and mic. Like the two-can telephone, you have a spring stretched tightly that carries a signal. But unlike the string in our previous example, the spring is flexible: even as it vibrates it stretches and gives, and this distorts the signal. The distorted vibrations push and pull on the diaphragm, much like the kid'a voice, and so it gets played back like a speaker. You wouldn't want to use a spring for a two-can telephone, because that kind of distortion usually isn't deairable. But it sounds funny, so someone got the idea to make a toy out of it."
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niitsk | how does painkillers know where the pain is? | Biology | explainlikeimfive | {
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"gz1yvi2",
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"text": [
"They don't. They simply inhibit the inflammation that causes the nerves to send pain signals, or the nerve signals themselves. That's the whole point, you don't need 100 different medicines for each body part because the drug effects the whole body.",
"Depends on the type of pain killer. If you mean things like ibuprofen (Motrin and Advil), they block inflammation. Non-steroidal anti-inflammatory drugs (NSAIDs) inhibit a specific enzyme that is involved in the inflammation pathway. Acetaminophen (paracetamol or tyelonol) is like a cousin of these drugs but it doesn’t really seem to block the inflammation, I don’t think we totally know how that works but it seems like it acts more in your brain and nerves to block the pain. Things like opioids work entirely differently. They block the nerves from sending the pain message to your brain.",
"I think what OP is asking is how are specially labelled pain killers different. Like how is \"Regular\" Advil different from \"Migraine\" Advil or \"Muscle and Joint\" Advil?"
],
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3
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nij3sj | how/why do opiates give you constipation? | Biology | explainlikeimfive | {
"a_id": [
"gz20pc1",
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"text": [
"Opioids prevent the stomach from emptying and the GI tract from performing peristalsis (which is the contractions within the stomach, small and large intestines that moves solids through them). This causes the food that you have eaten to not pass through your system (stomach, small intestines, large intestines) at its normal speed. By slowing this down, more water is absorbed from the food you have eaten while it is the system, thereby hardening your stool. This hardening of the stool turns into constipation.",
"Opioids and many other medications work as a lock-in-key mechanism. That means their molecule is the right shape to fit in specifically-shaped receptors. These receptors are commonly reused for different purposes all around the body - like how a switch in one part of the house turns on a light and another identical switch can turn on a fan, or the garbage disposal, or a particular outlet. Same type of switch, different thing happens. Normally (without medication) this isn’t an issue because systems are separated; by tissue, distance, other barriers. In the case of opioids, they spread throughout the body and they bind to the receptors which in one location decrease pain, but those same type of receptors in the intestines slow things down. Like telling someone to go into a house and flip on all the switches. Interestingly, several anti-diarrhea medications work on those exact same receptors in the GI tract to slow things down, but those medications are designed to be unable/less-able to get to the parts of the body that handle pain/euphoria."
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nij48s | Pulsating vibration of train tracks | We just moved near some train tracks. I've noticed when the big trains pass, it starts to shake the house and then turns into a pulsating vibration. What causes this? It's similar to the sound a train makes when passing. Why is it not just a steady vibration? | Physics | explainlikeimfive | {
"a_id": [
"gz237aw",
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"text": [
"I've lived in a house that does this occasionally. This isn't an ELI5, because it will probably be more suited to a engineer to explain. But, the tracks absorb vibrations as the train passes, which in turn is passed into the ground. Maybe poor maintenance contributes to it as well, tracks need to have ballast replaced to stop the sleepers moving, rails can warp (especially in warm weather) and cause them to arch and as a train goes over they bang onto the ground etc. This can send vibrations out through the ground and get the right train + speed + weight and you get a sort of resonance, which you will feel in your house. We live about 20 houses away from the tracks and can feel it usually at night when the really heavy goods trains go past. The houses on the ends of the street feel it much more.",
"D'you mean the *k'thunk k'thunk* sound and pulse when the car wheels pass where the end of one rail meets another?"
],
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nijgy1 | What is Variance and Standard Deviation? | Mathematics | explainlikeimfive | {
"a_id": [
"gz246vv"
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"text": [
"We use these for data where there are multiple values. We can use these values to make a distribution curve, which just shows how the data is spread out. If we plot these values on a graph, we get a bell shaped curve. We take the mean, which is basically the average of these values. So that's the centre of the curve. On either sides of this curve is the SD. And 1SD is 33% of the values. So if your mean is 1, and SD is 0.2, that means that if you add and subtract the SD, and make a range (in this case 0.8 to 1.2) that would just mean that 68% of the data comes in that range. So it's basically telling you how spread out the data is from your mean. If your data is close to mean, you'll have a small SD. If it's far away from the mean, it's a large SD."
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3
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nijh8r | How do 3D printers work? | Technology | explainlikeimfive | {
"a_id": [
"gz22yrj"
],
"text": [
"They work in a variety of ways, but the most common two types are FDM and SLA. FDM aid basically a computer controlled glue stick. It squeezes a long thin bead of semi molten plastic from a nozzle, which cools and hardens after it has left the nozzle. The part is split into layers, and the glue stick draws the outline of the layer, and then colours in the middle. It the moves up one layer and does it again until all the layers have been drawn. SLA uses a bath of liquid, which turns solid if you shine a bright light at it. So it uses a laser to draw on the liquid turning it solid layer by layer, much like the FDM a process drawing the outline and then colouring in the middle. The liquid is in a transparent tray and the laser shines up from below. There is a platform in the liquid which leaves a thin gap one layer in height to which the solidified liquid sticks. Once each layer is complete this platform moves up by one layer, leaving a thin layer of liquid under the solidified part, stuck to the platform and it all starts again."
],
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5
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nijs46 | Why a base 3 or base 4, computer is not practically used? Won't they be able to perform more calculations in lesser bits? | The argument I heard against this idea was lack of sophisticated hardware to differentiate more than two energy level i.e. high/low (0, 1). But why haven't we made such advancements to realize a computer with (0,1,2) or (0,1,2,3) as possible values per bit? | Technology | explainlikeimfive | {
"a_id": [
"gz256vp",
"gz24ove",
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"text": [
"We kind of have but I don't think it's what you were expecting. Sensing voltage is a far more complicated circuit and would take more area than the equivalent in binary which is what's more important in a CPU. An SSD on the other hand is trying to cram in a whole heap of data into limited space uses this technique. The NAND has a voltage corresponding to the 2, 3, or even 4 bit levels and then has voltage sensing on the outputs. Since there's only one set of outputs the voltage sensing circuit takes up a minimal amount of space on the controller's die.",
"Computers are all run off of series of switches that can be either on (1) or off (0). They don't have a 3rd and 4th state. Therefore, everything needs to be done in base 2.",
"You can do it, it just gets mucky We store multiple bits per cell in SSDs, up to 4 these days so each transistor has up to 16 different levels but you need a complicated circuit on the output reading what precise voltage level it's at You could build a computer that ran on 3 bits but the gate design and logic behind it are significantly more complex. Having a trinary system won't give a performance advantage, it'd be significantly worse for the first decade or so and at best catch up with binary systems. We're limited by heat, not how many bits things can handle so anything that increases the complexity of the gates means more heat and requires a reduction in speed to balance it out Engineering is all about balancing competing needs, binary computers are a better balance than trinary ones are"
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nikyyu | What is the difference between a yawn versus opening your mouth and taking a deep breath? | Biology | explainlikeimfive | {
"a_id": [
"gz4mbjt",
"gz5tf6y",
"gz8r9pg"
],
"text": [
"A yawn involves the “gasp reflex” that your body does naturally when you need more oxygen. It’s just a deep breath that your body does by force.",
"Not much. You can usually keep off a yawn with a deep breath. Yawns are you’re body’s response to needing more oxygen. The deep open mouth breath is just something you decide to do versus your body deciding.",
"A yawn invokes \"the satisfying breath\" in a way that breathing in deeply cannot. Being in certain states (e.g. anxiety) can make you feel as if you need to take a deep breath, yet breathing in deeply doesn't make this urge go away. Eventually, you yawn (or sigh) automatically and it hits the spot and satisfies the urge. I read about it once and, if I remember rightly, an involuntary yawn forces more air into the lungs than a voluntary deep breath does."
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nile3j | Why do we pee the bed as a child but not as an adult? | As a child you end up being the bed but by the time you’re an adult you’ve grown out of this. Does your body just adapt to not being the bed? | Biology | explainlikeimfive | {
"a_id": [
"gz2d2w2"
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"text": [
"You develop more bladder control as an adult so that you pee before you go to sleep. You’re also better at restricting your own fluids before going to sleep. Also, you have more of an awareness of bladder pressure and can wake yourself up prior to urination much more efficiently as a young/middle aged adult. Brain changes later can revert you to a less controlled enuresis behavior."
],
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13
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niljph | How does a defibrillator restore heartbeat? | Biology | explainlikeimfive | {
"a_id": [
"gz2dwm9"
],
"text": [
"Despite what they show in the movies, it can't start a heart that has stopped entirely. What it does is check that the heartbeat has a normal rhythm to it. If it's erratic and not beating normally, it sends an electric shock to try to put it back to a normal beat. Sort of like when you've got some appliance that's acting up and you kick it and it makes it work right again."
],
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6
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nim2sm | Why is it that whenever we buy a new electrical item like headphones or similar, it is usually pre-charged but only a bit rather than fully charged? | Technology | explainlikeimfive | {
"a_id": [
"gz2hblm"
],
"text": [
"Modern lithium batteries break down if they're left fully charged for a long time, *or* if they're allowed to discharge completely. When the device reads 0%, it really means 0% of the safe amount (and 100% is really 100% of the safe amount). They will *very slowly* discharge over time, so to safely stay on the shelf *after* manufacture, after storage, after shipping, and not either end up dangerously discharged there needs to be *some* charge, but they also can't be stored fully charged. So they're partially charged, usually about 2/3s full."
],
"score": [
47
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nimm2j | how dopamine and serotonin play a role in a.d.d.? I've been told there's lower levels, but also been told they're present but just not where it's needed at the moment. Which is it? | Other | explainlikeimfive | {
"a_id": [
"gz2ql42"
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"text": [
"The medical and scientific understanding of how ADD/ADHD occurs is still pretty controversial and not completely understood, but there are leading \"hypotheses\" which I will try to explain. This is a very complex area of neuroscience so bear with me. Brain cells use a variety of \"signaling\" chemicals, or **neurotransmitters**, to communicate with each other. The two most important neurotransmitters that are thought to be involved in ADD/ADHD are **dopamine (DA), and norepinephrine (NE)**. Serotonin (SE) *may* also play a small role, but that is an area of active research with even less scientific understanding. Will focus on DA and NE for this ELi5. Certain parts of your brain are responsible for concentration, logic & thought processing, as well as motivation. These parts of the brain make extensive use of **DA and NE** for communication and signaling between brain cells. It is believed that the communication pathways in this area of the brain are slightly impaired in those with ADD/ADHD. When brain cells communicate, they release stored DA and NE into their surroundings, which interact with and \"signal\" other nearby brain cells to do things. Once the job is complete, brain cells **recycle** the DA and NE they released and pump it back inside to their storage containers, terminating the signal to the neighboring cells. In conditions like ADD/ADHD, the leading hypothesis suggests there may not be enough dopamine (DA) or norepinephrine (NE) signaling in the parts of the brain discussed above. Either there is **not enough DA and NE released** by communicating cells, or the DA and NE released is **recycled** **too quickly** (or both) -- leading to the impairment in signaling. Medications for ADD/ADHD like Ritalin and Adderall, act by directly and indirectly increasing the effectiveness of DA and NE signaling in the brain. To keep it simple: they increase release of DA and NE by communicating brain cells, and they slow down the rate it gets recycled back inside the communicating cell. The research on how these drugs work is actually where much of the research of how ADD occurs comes from. We ***assume*** if the drug increases DA and NE, then they must be low in ADD -- which is why it is not a perfect science. I won't go into the other supporting research for it, since you did not ask. I hope I simplified things enough and this answers your question -- the actual processes above are much more complicated and difficult to describe especially without images. *\\[Qualifications: I am a medical doctor and have a bachelors degree in biochemistry\\]*"
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nimosy | Why tearing a paper sheet is easy but tearing multiple sheets is hard? | Physics | explainlikeimfive | {
"a_id": [
"gz2kg5j"
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"text": [
"Why is snapping a stick in half with your bare hands easy when trying to do so with a log is impossible? It’s more difficult to grip and tear something that’s thicker or has more layers. Especially something solid like a piece of wood or several pieces of paper."
],
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ninb4x | What does the A-10 “Warthog” accomplish that an AC-130 Gunship cannot? | Technology | explainlikeimfive | {
"a_id": [
"gz2obvt",
"gz2o4tk"
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"text": [
"The a10 is relatively fast and can get in, hit a ground target, and get out. The ac 130 in comparison is a huge, slow target. It does have bigger guns, more ammo, and higher loiter time, but the two aircraft really have different roles and applications. A single ac 130 also costs roughly as much as 10 a10 warthogs to build.",
"The AC-130 is basically an area effect weapon, whereas the A-10 is targeted destruction at the object in the flight path, so as the A-10 flies towards an armoured vehicle it can destroy it and anything sheltering around it, the AC-130 can plaster an area wiping out infantry and light armoured vehicles and soft skinned vehicles allowing infantry to retake an area or push through a space which has been opened up in the line."
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nink4i | How was it determined that nothing can move faster than light and why are we so sure of that? | Physics | explainlikeimfive | {
"a_id": [
"gz2qumx",
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"text": [
"We’ve done a ton of experiments and it always comes up with the same result. And the theory of special relativity makes a bunch of predictions about how things must behave, and it takes as *input* that light always goes a fixed speed, and those predictions have all been shown true as well. So we can’t prove nothing can go faster than light, because you can’t prove a negative, but *everything* we can observe and test in our universe is consistent with the predictions that result if that’s true.",
"Nothing has been observed to move faster than light. We based math off of that fact, and the math checks out."
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ninydp | why do our bodies develop tolerances to substances such as drugs, alcohol, caffeine etc.? | Biology | explainlikeimfive | {
"a_id": [
"gz2spvh",
"gz2rgcr",
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"text": [
"Effectively each of these chemicals bind to a specific receptor. Think of it like a lock and key. The keys float around and eventually bump into a lock causing the receptor to trigger. If these receptors are being triggered more than they should your body will turn the volume down. It can do this by reducing the number of locks, increasing enzyme production that destroys keys, or stop producing the keys it normally would for that lock as it is being replaced by the drug. These all play part in addiction and tolerance.",
"The receptors (like hugging arms) get worn out (tired of huggin) from the use of chemicals and become less sensitive (weak from huggin, can't hug as much)",
"I always explain it like this: your body likes being at a neutral level for everything, it doesn't like spikes in things like drugs or caffeine. So if the body knows its going to repeatedly get a drug, it learns to adapt by being less sensitive. And actually, the body counteracts the effects, if it knows its about to get a drug that raises heart rate for example, the body will prepare by lowing the heart rate before the drug is taken. Because that way it stays at its nice neutral level. This means your body will be less and less effected by a drug over time and needs bigger doses. The counteracting effect is also really dangerous because the body only knows the drug is being taken if its in the same environment as normal. So if you usually take tons of ecstacy in your room then your body knows: room = drug = counteract . Then you go out to a club and take the same dose, but without your body counteracting the effects, the dose affects you waaay more and you can overdose."
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nior1w | How do wireless phone chargers work? | Title. I’ve always been baffled that I can place my phone on a wireless charger and it instantaneously starts charging, yet no energy can be felt exchanging between the two. | Physics | explainlikeimfive | {
"a_id": [
"gz2w93d",
"gz2wjlg"
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"text": [
"Very basically (ELI5) a magnetic field will generate a current in a coil of wire. The charger makes a magnetic field and the phone has a coil of wire to pick it up.",
"There is a coil of wire both in the charging plate and phone. When electricity flows through the plate coil it causes a magnetic field to extend out from the wire. The wire in the phone reacts with the field forming an electric current that can be used to charge the phone. The concept is called induction. If you hold a strong magnet to the charging plate it will also react to this field. Look up solenoids for an understanding of how this works."
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nioymx | How do individuals like Winston Churchill successfully function despite heavy alcohol consumption? | Biology | explainlikeimfive | {
"a_id": [
"gz2y9p7",
"gz304re",
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"text": [
"Alcoholics build up a tolerance to the alcohol so they can function better than someone who is exposed to it for the first time.",
"Practice and speaking from unfortunate experience. Diving instructor and center manger in a tourist resort, drinking with the tourists every night and I ended up drinking around 10 pints and multiple large (local measures) shorts every night 7 days a week for around 4 years and was still able to open the center up every day, 7 days a week and work as a normal person. Drinking till the bar shut around 2am, drive back home, sleep for a few hours and get up and drive to the center to open it up for 8:30 am. Edit... country with a very relaxed drink driving law or basically if you can drive without causing an accident, they will ignore you",
"Chronic alcoholics eventually develop the ability to function at some level. It becomes their new normal."
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nip6d1 | Compared to other foods, why are bread and pastries fine to sit out without refrigeration? | Chemistry | explainlikeimfive | {
"a_id": [
"gz2zg8j"
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"text": [
"They are dry, and often have a preservative such as salt. If you did refrigerate bread it would last longer."
],
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3
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nipan9 | Why does leftover chicken and turkey taste so different, even after it’s been fully reheated? | Other | explainlikeimfive | {
"a_id": [
"gz31awt"
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"text": [
"The reason ... can be attributed to exposure to oxygen, which causes deterioration of the polyunsaturated fatty acids in the chicken. This, in turn, affects the flavor of the meat. Read More: URL_0"
],
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"https://www.mashed.com/208064/why-chicken-tastes-different-when-its-reheated/"
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|
nipw8q | how do teeth stay in your mouth? | What it says in the title. How is is teeth stay in there? The adult teeth push the baby teeth out and take their place, but what kept the baby teeth in there? What keeps the adult teeth in once they’ve moved to their places? Also what happens to the pocket place where the adult teeth were before they came in? Edit: everything online just says the jaw and periodontal ligament keeps them im place but teeth stay in place after death so it’s not the ligament, and I don’t see any way the jaw can hang onto a tooth | Biology | explainlikeimfive | {
"a_id": [
"gz32m4o",
"gz32o9g"
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"text": [
"The roots keep your teeth in! Baby teeth have roots too, but as the adult teeth come in from below, they push on the baby teeth roots and cause them to break apart/dissolve. That’s why the baby teeth fall out painlessly - their roots are already gone.",
"Teeth have roots that hold themselves in place in your gums. The roots of baby teeth basically disintegrate and the gap left behind is occupied by the erupting adult tooth. There is no \"pocket\" left behind because it isn't the adult tooth \"moving\" into place, but \"growing\" into place. What is \"left behind\" is the newly grown root of the adult tooth which is what pushed it into place in the first place."
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niq6g1 | -What are the other theories of the universes origin,besides the Big Bang? | Physics | explainlikeimfive | {
"a_id": [
"gz35xmn"
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"text": [
"The only modern competitor to Big Bang I know of that was ever taken seriously was the Steady State theory, which argues that the universe has no \"true\" beginning or end, and spacetime is expanding just because that's what it does, and new matter is created as it expands... trying to explain it now it almost sounds like a troll theory. Steady State was pretty thoroughly lambasted by the 1970s though. In favor of Big Bang which far more closely matches the evidence we have. Nowadays, \"The Big Bang Happened\" is pretty much accepted fact in the scientific community, with debate being mostly around the fine details of the event rather than the general idea."
],
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niq7nq | Why does it take 30 minutes for human eyes to adapt to the dark, but only a few seconds to adapt back to the light? | Biology | explainlikeimfive | {
"a_id": [
"gz352di",
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"text": [
"Fully adapting to the dark takes about 20 to 30 minutes. For this your cones and rods (they are in charge of absorbing light and transforming it into an image) need to go through a series of biochemical events to change the number of molecules released by your photoreceptor (what perceives the light) while going to the light the pupil only needs to get smaller and the process that the cones and rods do is way shorter since its basically just relaxing cells while dilatating the pupil does the opposite, hope it helps",
"The way we see light is that our rods and cones are constantly producing chemicals which gets broken down whenever they are exposed to light. We then measure how much of this is happening to find out how much light hits our retina in different places. When you are in the dark your rods and cones are full of these chemicals and when you step out in the light the chemicals all break down almost instantly. But when you step into the dark again the cells is still almost empty of the chemicals and it takes quite a while for them to produce enough chemicals to fill the cells up to their usual levels."
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nir5hn | Why do we put and injured finger in our mouth? | Eli5: i just smashed my finger in a drawer and immediately put it in my mouth - why? Like - if u smush or cut your hand, why is it instinct to shove the digit into your face? | Biology | explainlikeimfive | {
"a_id": [
"gz3cq9n",
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"text": [
"Your saliva has pain relieving qualities. It contains a protein that speeds up the cell making processes. Maybe you just know it helped in the past hahah",
"The mouth is the main gate to getting into the body. As such the defences are strong there. Saliva can provide antiseptic and pain relief."
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nir6h3 | Why does tobacco contain harmful chemicals like arsenic and tar and marijuana doesn't, when both are natural plants? | Maybe weed does have harmful chemicals but you don't see them advertised like cigarettes. What's the deal? | Chemistry | explainlikeimfive | {
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"Marijuana smoke has just as much, if not more, harmful stuff than tobacco smoke - URL_0 The difference is *how* people smoke. The \"average\" for cigarette smokers is a pack a day - 20 cigarettes. For some people it's less, for some people it's much more, but whenever you see statistics about smoking, it's usually based on that pack a day number. People are *not* smoking 20 joints a day. So, they're still getting harmful chemicals in their lungs, just a *lot* less of 'em."
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nirqih | how is it that when you pee, all the colour from what you’ve had to drink is taken away? | Biology | explainlikeimfive | {
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"Excess liquid you drink does not go directly to your bladder to pee out. Urine is extracted from your blood by your kidneys. When you drink too much liquid, it needs to get absorbed into your blood by your intestines before being filtered out of your blood by your kidneys. The ‘color’ in your drink doesn’t make it through this process. It’s more likely that the color will stay in your intestines and affect the color of your poop.",
"Because of what your body does to the drink, which is kinda complicated: Drinks are made up of a bunch of different chemicals. Some of those are useful to the body, so it keeps them. Some are harmful, so it gets rid of them in urine. Others don't ever go inside the body at all, they just remain in the digestive system. Let's follow a drink from your bottle to your toilet. You have a can of diet pepsi. In this diet pepsi are many different ingredients, but the ones we'll look at are water, carbon dioxide, aspartame, caffeine, sodium benzoate, and E150d. Water is the base of the drink, carbon dioxide is what makes it fizzy, aspartame is what makes it taste sweet, caffeine is what makes it addictive, sodium benzoate makes sure it's not too acidic and E150d gives it that coke colour. You take a drink, and the pepsi goes down your neck, into your stomach, and then into your small intestine. In your small intestine, water is absorbed into the blood stream, hydrating you. Carbon dioxide is absorbed into the blood too. Aspartame however degrades rapidly into three new chemicals: aspartate, phenylalanine and methanol. All three of those things are absorbed into the blood, but aspartame is so easily degraded in the small intestine that no aspartame survives long enough to be absorbed. Caffeine is absorbed too, as is sodium benzoate. E150d however isn't absorbed, because the cells of the small intestine don't have the ability to absorb it. The colour component of the pepsi remains in your digestive tract, and will continue on down that until excreted as faeces. Since that's already brown though, you obviously can't look at it and go \"oh yeah that's the colour of pepsi!\" Meanwhile, the elements of the pepsi that entered your blood are water, carbon dioxide, aspartate, phenylalanine, methanol, caffeine, and sodium benzoate. Of those, carbon dioxide, methanol, caffeine and sodium benzoate are all poisonous, so the body needs to get rid of them. Carbon dioxide is easily removed - the blood hands excess carbon dioxide to the lungs, which gets rid of it by breathing out. The liver gets rid of methanol by turning it into acetic acid, which can actually be used to generate energy in a similar way to sugar. Caffeine is slowly degraded into three less toxic molecules (which I'll just call dead-caffeine to avoid throwing even more fancy words into this), and sodium benzoate is turned into hippuric acid. So, finally, the body has to get rid of the three kinds of dead-caffeine and the hippuric acid. It does that through the kidneys: These bad chemicals are extracted from the bloodstream, diluted with a bit of water to prevent them solidifying as kidney stones, and sent to the bladder for later urination. So the end result is that of the six chemicals we tracked in the diet pepsi, only one of them actually made it all the way through the body into the bladder: the water. The others were tragically lost along the way - one became faeces, another was breathed out, and the rest were transformed into more useful and/or less toxic chemicals. Nothing of the original pepsi remains, so the colour of your urine is determined instead by the colours of these new chemicals, and of other poisons pulled out of your body by the liver."
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nirybz | Why does boiling water remove some contaminants? | In those survival shoes (á la Bear Grylls), he insists that boiling water before consuming it is essential for removing natural toxins. What does this process look like? Are there some toxins that aren’t affected by boiling water? | Chemistry | explainlikeimfive | {
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"Many natural toxins, and virtually all natural organisms capable of producing toxins, die at boiling water temperature. The heat denatures proteins, disrupts most organic molecules, and general screws up all the chemical reactions that make life work, so it tends to render water safe(er) to drink. It doesn't \\*remove\\* the material, the atoms are still there, but it converts the molecules to forms that aren't harmful to us. Simple poisons, like cyanide, and many industrial chemicals like fertilizer, aren't inactivated by heat, so this method isn't foolproof, but in a survival situation you're probably not dealing with industrial pollution, you're dealing with natural bugs and their toxins. And boiling is nearly foolproof for that.",
"Those \"toxins\" are bacteria and viruses. Bacteria are living things, just ... much smaller than me and you and usually just made out of one cell. Viruses are not living but they can be destroyed by high heat, just like leaving a thin glass on a stove set to max. In reality, you don't *need* to boil the water to kill these things off - they start to die out at temperatures *lower* than boiling. But, if you're out in the wild without a thermometer and you don't remember the chart of several dozen different things and their heat tolerances.... then just getting the water to a boil for a few minutes, which is hotter than it needs to be, is a really easy way to tell that it's hot enough. Now, this isn't going to get rid of like mercury or lead or anything like that, but you're also usually not going to be concerned about mercury or lead in a random river in the middle of the woods.",
"Typically boiling water eliminates parasites and many germs by killing them with heat, this would not however remove dirt and other types of contamination that filtration would eliminate or minimize.",
"You do not boil water to remobe toxines. Toxines are poisons produces by somthing biological and water in geneal do not contain it to any dangerous degree. You boil water to kill microganims and viruses. Microgoanism are small living thing like bacteria, amoeba and other living thing in the water. You destory by heat ust like you would get burned if yoi dip you hand in water. Or look how meat chagnes if you boil it. The remain of them will still be in the water you drink, but they are not dangerous boild you have just created a broth. Comare to beaf broth that is the same but with cells from larger animal. Dead micorganims is just food to use. There is stuff that can be in water that boiling has no effect on, microganis do produce stuff that is not broken down by boiling water but there will not be a lot of water in nature. There can be danerous level in rotten meat that is whay you can't just heat and it it. Poision of nonbiologial sources can alos be in the water and survive boiling like heavy metal and stuff produce in human chemical industy. So there is in general not a lot of toxins in water but there can be bacteria, viruses and other stuff that can make you sick and you kill them by boiling the water.",
"Boiling water kills microorganisms and bacteria. If you want purified water you setup something above the boiling water to collect the water vapor as condensation. Look up how to distill water. It is not completely pure but much purer than just boiled water. If you are in a survival situation lifestraw is a portable filtering device that filters water making it safer to drink. Both of those methods will remove dirt and other solid particles."
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nis2ak | what causes a baby’s first breath? | Biology | explainlikeimfive | {
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"Before a baby is born, their lungs are filled with fluid. They sort of \"practice\" breathing motion while still in the womb, but they are receiving oxygen from through the umbilical cord. There are series of changes when a baby is born, and it takes 10-30 seconds after birth for a baby's first breath: 1. Labor contractions and hormonal changes during labor help reduce the production of the fluid in their lungs in the womb and start draining the fluid and absorbing the exiting fluid. 2. When exposed to the air, the temperature change and lack of fluid help trigger the baby to start breathing 3. The umbilical cord is cut, completely removing the flow of blood with oxygen 4. As the baby breaths and is exposed to air, the fluid that was in their lungs while in the womb will continue to dry up In a c-section birth, if labor was short, the baby may take shallower breaths since more fluid remains. Handling can encourage the baby start breathing, but it is not the main reason they start breathing.",
"The hormone oxytocin gets produced during physical contact and very important for mother-baby bonding. ~~It is also one that triggers the first breath response when the baby is being handled as it is born.~~ this is wrong, apologies. See u/EliannaRys for the more accurate answer In water births, midwifes have to be careful how they handle the baby as it’s being born (or not handle it at all) since overstimulation would trigger the breathing reflex under water. Edit: just noticed your username. Guessing by this question that it is no longer relevant? If so congrats! edit: removed incorrect statement"
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nisbov | What is Torrent seeding and how does it help? | Technology | explainlikeimfive | {
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"Torrenting works on the basis that instead of you getting a big file from a single source you instead have a bunch of people who each give you a little piece of the file you want, and you give them little pieces you have that they need. A person who is giving away pieces of the file to others, even if they already have all the file, are seeders. They are \"seeding\" the file.",
"Torrents work not by downloading a file from a set server, but by individual people, or peers, sharing the file they have already downloaded. The original uploaded cannot be expected to keep the file available forever, so it becomes the responsibility of the people who have downloaded the file, such as yourself, to share, or seed, to future peers. Only by seeding everything you download to (at least) 1:1 (give back an equal amount as you've taken) are you helping to keep torrents alive. TL/DR: if no one is seeding, no one else can get the files."
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nisqut | When searching for life on other planets, why do we look for oxygen when the species there could have a completely different structure where they don't need oxygen at all? | Biology | explainlikeimfive | {
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"First, oxygen is highly reactive, and a dead world would have long since had its oxygen taken up into metal oxides, burned into carbon dioxide, etc. A world with significant amounts of free oxygen has *something* producing it- either life, or an interesting chemical thing that on its own would be worth figuring out. Second, it's easier to look for what we *know* is used for life rather than speculate a ton of alternate biologies, look for their own volatile gasses, and just *hope* it indicates life.",
"Because there's no other leads. We don't know if they don't need oxygen/water, we don't know if they do. All we know is that *we* need it, and so we know that there are ways to create life that do need water.",
"Short answer: we **don’t** look for oxygen. As u/atomfullerene mentions, we don’t have the ability to do that yet, and it’s a common misconception that oxygen is what we’re looking for.",
"This is a bit of a misconception, but it's easy to see where it comes from given how people talk about exoplanets. So first, we can't quite look for oxygen yet in exoplanets. The technology isn't there yet but hopefully will be soon. But aside from that, there's a general disconnect between how scientists actually do research looking for \"earthlike planets\" and how it gets described. So you always hear \"we found this earthlike planet\" which could be the right size or have liquid water or whatever. And naturally people think scientists are just out looking for those planets specifically. But in general they are just finding thousands of planets with a huge range of traits and simply highlighting in the news \"oh, and this one had a trait that was earthlike\". When we can get amospheric spectra, you can bet something similar will happen. They will find a bunch of planets with no air and planets with thick venuslike air and planets with hydrogen rich atmospheres...and occasionally one with oxygen will pop up in the news and get a bunch of press because it could be earthlike! And people will think scientists are only looking for those planets, but really they are looking at all the planets and those are just the ones that get in the news. Also you can bet that if scientists find a weird atmosphere (say, flourine rich) that looks different from all the other atmospheres, people will speculate it has life in it.",
"In order to use energy you have to take it from somewhere and put it somewhere else. In the case of chemical energy, you have to break weak, unstable bonds and form strong, more stable bonds. Since all chemistry boils down to how atoms are sharing their electrons, the most energy you can get is going to come from an atom grabbing onto an electron really hard to form that strong, stable bond. Few elements will grab electrons harder than oxygen. That's what oxygen is doing in our bodies: it's the end of a long chain of passing an energized electron between different molecules, incrementally taking some of the energy out of it until the oxygen takes it. It's like pouring water through a generator. You can either start with water really high up, or drop it really far down. Oxygen is *almost* the most \"down\" the electron can get. Almost, because fluorine would be lower, but fluorine is more dangerous and harder to get. It's dangerous because it can grab electrons from other molecules that aren't supposed to be giving them up, ruining that molecule and damaging the cell. In fact, oxygen does this, too, and your body has a lot of mechanisms to control it as much as possible and repair the inevitable damage. Fluorine grabs electrons *so* hard that it's virtually impossible for your cells to control it. Fluorine also holds onto the electrons it's already grabbed super hard. Fluorine forms *very* stable bonds, which means it's not usually free to form new ones. If you're pouring water through a generator and the hole it ends up in is already full, the water can't flow through the generator. To empty the hole, you have to add energy back in - by definition, more than you get back out. Bonds with oxygen are also very strong, but they're *just* weak enough that clever bacteria evolved a way to use sunlight to break those bonds and form free oxygen. The energy is free, provided by the Sun, and very plentiful. But sunlight isn't powerful enough to break fluorine bonds, so there's no fluorine available to use to take electrons in your cells. All of this makes oxygen the ideal source of energy for all living things. The physics that make that true on Earth are true everywhere else. It's absolutely possible for life to use something else - life on Earth did so for millions of years before cyanobacteria evolved photosynthesis and aerobic respiration, and still thrives in oxygen- poor places on Earth. However, life without oxygen doesn't have nearly as much energy to work with. Complex, multicellular life is *possible* without oxygen on Earth, but it's very very rare. With a few exceptions anaerobic life is limited to single cells like bacteria and archea, and slime molds. Also, because oxygen is so reactive it doesn't tend to stick around long as O2 before bonding to something else, like carbon to make CO2. If O2 molecules are abundant in an atmosphere, something has to be constantly making it, probably by ripping it off other molecules. That takes adding energy in. There are chemical processes that do that without life, but it *could* be an early, obvious sign that's worth looking into. Of course, there could be another way for complex life to form. There *is* at least one example of an anaerobic vertebrate species of fish here on Earth. But our life is all we have to base our assumptions off of so it's a good place to start.",
"I’ve asked this very question before! What if there’s a species of worm-like creatures living in the Martian soil that doesn’t need oxygen or water to survive? Doesn’t water and oxygen just support Earth life? A great answer I received was “When searching for cows, we search in farms and ranches instead of cupcake shops.”",
"If you don't search for oxygen, what do you search for? No one knows the answer to that question. Yes, maybe there is some very strange form of life out there that doesn't need oxygen, but we'd have no clue what to even start looking for. Since we can't look for something that we don't know exists, but look for life like ours, because we DO know what that looks like and have some ideas on how to detect it.",
"It seems to me that if the life there did not rely on oxygen, we might not even recognise it as life. Something non-reliant on oxygen might, and might well coexist with it, but it could be completely foreign to us.",
"URL_0 . This was an excellent overview of that question that others have already answered clearly, but which also covers many of the other kinds of chemical signals and how no single one alone is really proof. There are tiers it turns out of things that could be due to life but that could also be due to unique chemistry.",
"Carbon (and possibly silicon) resemble universal building blocks the most. Think of carbon like the ultimate Lego block. Imagine building carbon based life, you'd be adding metals like iron to bind that carbon together in unique ways to create new shapes. You'd also need a fuel source. CO2 is an end product that is easily made from O2 in our bodies. They just work together well . The biggest factor however is that we know oxygen is a crucial ingredient for life on earth. Other life forms in our size can be theorised, but noone knows if it would actually be possible or if they even exist at all. But we know humans exist. When youre looking for your phone, the first place you look isn't the freezer. Even though it might be in there for some reason.",
"Because we can't find evidence of a life-support system (i.e. whatever their version of oxygen is) if we aren't familiar with that kind of life. We would need to directly observe the life *first*, and then we could analyze that atmosphere, etc. and extrapolate to other planets.",
"The answer to questions of this type (\" why do we look for X, if there could be something completely different?\") can be answered with \"we are not looking for X _only_, we are looking for X _first_\" ELI5: When I'm looking for my phone, I first look on the desktop or in my backpack. That doesn't mean I won't look for it behind the couch, but let's start with the usual places first.",
"As far as we know, free Oxygen is very special for complex life, almost mandatory. Anaerobic life takes an order of magnitude more food to achieve the same metabolic activity. Free Oxygen occupies a very special place chemically where you can just about heal the damage it causes to your body while still having the energy for higher processes. So far, we haven't found many chemicals that can do that, and most of the alternatives can only be made in a lab. So, although we certainly realize we may be wrong in myriad assumptions, as far as we can tell, it's by far the best chance we have of ever finding anything bigger than a bacterium. More info here for example: URL_0",
"We only know what hydrogen-based life looks like because all life on Earth is hydrogen-based, and we know how it uses oxygen. We have theorised that silicon-based life is possible, but until we observe little rock-like things moving on another planet we have no real idea what that life would look like or how we’d find it. ETA: Sorry, I meant carbon-based life. Hydrogen-based life has never been found, and I’ve no idea why I typed it. Water on the brain, most likely."
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nitubi | Does it matter which one of the millions of sperms that impregnate the women? | I’ve been thinking of it since I saw a meme about sperms swimming to the egg, and one was a doctor, one was a scientist but the one that got to the egg was a looser. So the question is; does it matter which one of the millions of sperms won the race? Would you still be the same person if sperm number 124737488 got to the egg rather than sperm number 48373749? | Biology | explainlikeimfive | {
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"As others have said, the specific sperm determines which half of the father's genes the baby has, which makes a difference. But it's important to realise that it's nowhere near as clear cut as the meme: that one sperm will produce a doctor, another will produce a scientist, or a loser. Careers and general competence in life are much more dependent on childhood rearing, parental guidance, education, and other factors that happen after birth. The best way to think about the difference between individual sperms is to think of the difference between siblings. One child might grow up to be a doctor, while their brother/sister might choose a career as a scientist. But if both are from a well-off family who values education, both are *likely* to have good careers, whereas if they'd been born into a poor family with abusive parents, both will more likely end up struggling all their lives. It's possible to defy these and have a loser come from a well-off family or a successful person come from a bad background, but it's mostly going to be the circumstances around them in later life, not which sperm/genes they got.",
"Yes, it does. Each sperm carries half the genes of the man it came from, and *which* half is different from one sperm to the next.",
"> I’ve been thinking of it since I saw a meme about sperms swimming to the egg, and one was a doctor, one was a scientist but the one that got to the egg was a looser. So the question is; does it matter which one of the millions of sperms won the race? Would you still be the same person if sperm number 124737488 got to the egg rather than sperm number 48373749? Of course. All of them carry different variations/mutations of the same genetic information (not to mention one of father's two sex chromosomes, determining the sex of the embryo). They are all unique.",
"Yes it does matter. Every cell has a chromosome pair. Exept for gamets. They just got one half of the pair. So it has either the one or the other chromosome. In cases of the sex chromosome, this is highly infulential, but also the others play a BIG role. Think of it this way. Your cell got one chromosome from your mom and one from your dad. Then it mixed em up. Now you give one of those mixed up chromosomes to your child. The question is just which one of the mixed ones.",
"Does it matter? Yes as it determines which half of your father's genes you're getting. Otherwise, all of your siblings would be genetically identical to each other. It's not like the meme though because stuff like whether or not you'll be a doctor or a scientist or a bum has pretty much nothing to do with genetics."
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niu6gj | How is it when we take a nap, that our body recognizes we need to be up at a specific time rather than sleeping the whole evening or our regular sleep schedule? | Biology | explainlikeimfive | {
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"The body doesn't \"recognize\" that you're napping, it's because you haven't been asleep long enough to reach the deeper sleep stages. That's why it's important to time the length of naps accordingly. Otherwise, if you're asleep for too long and reach the deeper sleep stages, waking up abruptly will cause you to be quite drowsy.",
"Sleep is run by two processes in the body. The first is called sleep-wake homeostasis. It basically works by making you more sleepy the longer you have been awake and less sleepy the longer you have been asleep. This is judged by the amount of adenosine hormone. Caffeine blocks adenosine recptors so that is how it can give you a burst. The second system is the circadian rhythm. It does many things but with sleep it will keep you asleep when the sleep-wake homeostasis would awake you up and it keeps you awake when sleep-wake would tell you to sleep. It uses cortisol and melatonin to do this. There is usually a period in the afternoon around 2pm or 3pm where the sleep wake cycle tells you that you are sleepy but the circadian rhythm hasn't kicked in yet to keep you awake. So if you sleep at this time you will likely get up in an hour or so because of the circadian rhythm. It starts kicking in and by 5 pm you probably would not be able to sleep too well. Also it is generally recommended not to have caffeine after noon (or about 8 hours before bed) but it you have coffee during this sleepy time then it shouldn't disrupt your night time sleep since it's not interfering with circadian rhythm. The reason I said usually is because this is the usual time for most adults but if you are in early twenties or teen then your circadian rhythm is shifted to later AND you need more sleep than adults. So for teens it's a longer sleepy time about 2 hours and it's starts at 3pm. Only about 20% of adults are true night owls or larks but if you are one then your rhythm might shift one hour ahead or behind a normal adults too. Additionally, you can train your clock to be ahead or behind as well but even if you are getting enough sleep over the long run if it's not your ideal sleep schedule then it can effect your health. Finally, I will say by historical accounts it has only been recently that we slept 8 hours through. Perviously we would break the night into two parts with about an hour or two at night where people were awake. Usually people would eat, have sex or even visit neighbors before going to sleep again. We don't know if this was common prior to middle ages because that was when we have the written accounts so it's hard to say if humans have been doing that since before we left africa or if they were sleeping through the night. Not everything that people did in middle ages was healthy or \"natural\" human behavior. So I am not saying people should have two sleeps at night but it could be that we are supposed to. If this is the case then the answer to your question might be a little different since the premise is that humans sleep through the night but we don't know for sure that is ideal or just the norm today."
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nivq48 | How come birds don't get electrocuted when they stand on power lines/phone lines? | Technology | explainlikeimfive | {
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"Electricity is a very lazy force. It won't flow through a path if it can't get any benefit from it. Each of a bird's feet is on the same line, and so they're at the same \"electrical potential.\" The electricity in the wire has no motivation to travel through the bird's body and back into the same wire. Now, if the bird were somehow able to plant one foot on an energized wire and touch something at a lower potential (closer to the \"ground voltage\"), electricity *would* flow through that path because it goes to a lower potential, and you would have one very crispy bird. This happens with squirrels more than zero times a year.",
"Because they're not grounded. You too could hang off of one and be safe. Just don't get up there with a metal ladder..."
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nivqdw | How do serotonin levels control people vomiting? | Biology | explainlikeimfive | {
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"Nausea and vomiting are controlled by specific nerves. In particular, they're triggered by activity on the [5-HT3 receptor]( URL_0 ), which is all over the neurons in your gut. 5-HT3 is a serotonin receptor, so things that mess with serotonin in general mess with its activity - in particular, it's why nausea and digestive problems are major side effects of medications that mess with serotonin. Some drugs target 5-HT3 in particular, including some of the most common anti-nausea drugs."
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niwhxd | If humans stop producing cancer CEA (carcinoembryonic antigen) after birth, why are some levels considered normal to have in blood tests? | Biology | explainlikeimfive | {
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"It's a combination of two different things: Tests aren't perfect and things that aren't CEA could be picked up as CEA in the test which is called a false positive. Having an upper normal threshold means that you don't have a lot of false positives that cause unnecessary concern. Even though its meant to be switched off, your body has billions of cells that are all kind of doing their own thing. Sometimes there might be some alterations in particular cells that mean that they're still expressing CEA. So it produces a normal, very low level. This is in contrast to a tumour where there's millions of cells that are all expressing CEA which makes your levels go up significantly."
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nix06n | How can Iphones detect liquid in the charging port if waters trapped inside and you try to charge it? | Technology | explainlikeimfive | {
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"It senses more than one contact is touching themselves with each other and it shuts the port off until they stop touching each other."
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nixb2y | Why does carbon monoxide bind more easily to hemoglobin than oxygen? | Biology | explainlikeimfive | {
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"The answer has a lot to do with the biochemistry of the **heme-pigment molecule** (the part of hemoglobin that carries oxygen) as well as the very sophisticated conditions within the bloodstream that change how heme behaves with respect to its binding affinities for oxygen -- in other words hemoglobin switches back and forth between \"wanting oxygen\" and \"not wanting oxygen\" depending where it is in the body. & #x200B; > The tl;dr answer is that hemoglobin actually does not like oxygen very much, but conditions around it help it bind or unbind depending on the situation. Hemoglobin binds carbon monoxide over 200x more effectively than oxygen because CO stabilizes the heme in a much more \"comfortable\" state. \\--- The real details --- At the center of the heme-complex is a single molecule of iron in the ferrous state (Fe^(2+)) which is stabilized by an array of other amino acids (protein building blocks), akin to the scaffolding of a building. This scaffolding maintains stability of the heme complex in various states, such as when it is bound to gas molecules (oxyhemoglobin, carboxyhemoglobin) or when it is unbound (plain hemoglobin). Also understand that the protein hemoglobin actually contains ***four*** heme complexes, so therefore one hemoglobin can carry 4 molecules of dioxygen/O2. In order to understand why CO displaces oxygen it helps to understand how oxygen binds in the first place. When blood containing unbound hemoglobin circulates to the lungs, **the partial pressure of oxygen (pO2)** in blood from the alveoli (lung air sacs) **is incredibly high** (about 100mmHg) and is the **main determinant that facilitates O2 binding** to the ferrous ion (Fe^(2+)) of heme, the latter of which becomes reduced to ferric (Fe^(3+)) when holding oxygen. Another important component is blood pH which is slightly less acidic in the lungs compared to other tissues -- the higher pH causes slight changes to the protein scaffolding of heme which stabilizes the Heme-Fe3+-O2 complex. There are other, less important factors at play (e.g. temperature, CO2, phosphate and something called 2,3-DPG which is beyond the scope of this ELi5 to go into). The point is, when hemoglobin is in the lungs, it **REALLY WANTS** **TO BIND OXYGEN** (and it actually does not want to get rid of it either). When blood containing oxyhemoglobin reaches body tissues, such as your heart, **the partial pressure of oxygen (pO2)** is much lower (closer to 40mmHg) and the pH is also relatively more acidic from metabolic activity. The partial pressure of CO2 (pCO2) is also higher from tissues using oxygen. All of these factors (and a few unmentioned others) shift hemoglobin's behavior to **WANT TO RELEASE OXYGEN**. This is a good thing because the body tissues want oxygen, and hemoglobin wants to get rid of it. One other factor of hemoglobin binding that relates to your question goes back to those ***four heme complexes*** per hemoglobin molecule. As one or two heme complexes bind oxygen in the right conditions, it makes the remaining 2-3 much more avid at capturing a molecule of oxygen. The reverse is also true. As oxygen leaves 1 or 2 of the heme complexes of a hemoglobin, it makes the other 2-3 filled complexes more efficient at giving up their oxygen too. I will come back to why this matters in a moment. Now that you hopefully understand oxygen behavior, can discuss carbon monoxide (CO). **The affinity of heme pigment for CO is** ***over 200x greater than that of O2***. That is one of the most important concepts here. I have explained how oxygen dynamically shifts on and off heme pigments based on the location in the body. CO does not need any assistance from blood pH, CO2, phosphate, or 2,3-DPG in order to bind to hemoglobin the way oxygen does. When CO encounters a heme complex, it binds and stabilizes the iron in the Ferric state and remains that way as carboxyhemoglobin. This is a matter of thermodynamics. The dynamic conditions that affect oxyhemoglobin don't really affect carboxyhemoglobin. When hemoglobin reaches body tissues, O2 drops off and a CO can easily sneak on. Worse still, once one heme complex binds CO it locks the other neighboring heme complexes I talked about earlier to hold their oxygen and not release it to tissues (much like the behavior of hemoglobin in the lungs). This is very problematic because any carboxyhemoglobin essentially is useless as a carrier of oxygen if it wont deliver anything to tissues. The only way to reverse this process is time, and by providing very enriched oxygen at a hospital (to raise the pO2 of blood) so that hopefully you can drown out the CO. **In summary, hemoglobin's chemistry favors treating O2 like a used hooker but treats CO like its boo.**"
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nixinz | How did the Great Depression end? | Economics | explainlikeimfive | {
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"was a long process but the 2 main factors that pushed for its end were the changes to the economical systems that were needed to prevent this from happening again(the introduction of regulatory bodies is what kept everything in check+ reforms that aimed to make these economies less restricted to grow.) the other factor was World War II opening the avenue for a huge rise in demand for goods. this created jobs and industry sectors."
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niz1as | why do most animals not have a father-offspring relationship? | Biology | explainlikeimfive | {
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"Evolution didn’t seem to care all that much for the “strong male role model as a father” propaganda. As far as evolutions goals, passing on an individuals genetic material is more important. If a male could easily mate with a dozen females per season, it could give him a better chance of his offspring surviving than being in a monogamous relationship and raising that kid."
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niz5wd | Do animals and humans have the same blood? | Do animals and humans have the same blood? If not .. why? What makes them different? | Biology | explainlikeimfive | {
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"No, they do not have the same blood. The specific thing that makes makes them different is our different genes. More broadly, it’s our different needs that make us different. You will find that most creatures have the same basic elements to their blood - plasma, platelets, red blood cells, white blood cells, etc. But what those cells look like and what they can do is very different in different animals. Camels, for example, have oval-shaped red blood cells where we have disk-shaped red blood cells. This is so that camels can drink and take onboard huge amounts of water all of a sudden without their RBCs bursting. Dolphins and whales have red bloods cells shaped in a way that maximises oxygen carrying capacity, more than ours do. This allows them to hold their breath far longer than we do.",
"Not the same, but pretty similar if you look at similar animals. Like humans, other mammals have red blood cells, white blood cells, platelets, and blood plasma, which all perform basically the same function in those animals as they do in humans: red blood cells carry oxygen, white blood cells destroy invaders and damaged cells, platelets form clots to stop bleeding, and plasma contains various dissolved proteins and nutrients needed for life. There are slight differences (e.g., in the size of red blood cells), but the basic plan is the same. The further you go from mammals, the more different things are. Non-mammals don't have platelets, for example (although their blood still clots). Some other animals use a different chemical to carry oxygen (humans use hemoglobin but, say, squid use a related chemical called hemocyanin). Very simple animals like jellyfish don't have blood at all."
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nizp2y | If the brain has no pain receptors, why do humans have headaches? | Biology | explainlikeimfive | {
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"Biologist here! Because, while the brain has no nerve endings, our heads are full of them. Headaches are generally related to the muscles around the skull and at the base of the neck, its just nerve endings around our sweet thinking meat that are hurting",
"Headaches aren't the brain reporting pain, but rather other things in the area. Blood vessels, meninges (layers lining the skull/brain), muscles, and bone are all capable of complaining."
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nj00nz | When objects move does it affect earths rotation? | Clarification: I’m using “objects” as everything that can move (i.e cars, bicycles, humans, animals etc.). | Earth Science | explainlikeimfive | {
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"On a fraction of the most smallest, most microscopic insignificant level you can think of, to the point where the answer would probably be no. Even the giant earthquake in Japan some years ago had a negligible impact of altering the length of a day by like a super nanosecond.",
"Yes, in the strictest physical sense, but not for any practical purpose. Even whole continents are not significant parts of the Earth's full mass; tiny objects on their surface are even less significant."
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nj1ubb | How does the skateboard not fall off during jumps? How does it stick to the feet? | Physics | explainlikeimfive | {
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"Physics. Usually the board is rising upwards after a trick, etc. The skater uses their feet to stop the upward movement.",
"When you jump on a skate board you aren’t just jumping up. You also push down on the board in a specific way to get it to pop off the ground with you. It’s a lot more complex than it seems. Source: I managed to do an Ollie once.",
"If you're only watching videos of complete pros doing jumps, it looks like the board is sticking to their feet. Try watching amateurs attempting even simpler jumps. It's obvious that if you don't get the timing and the angle of the jump absolutely perfect, your feet won't touch the skateboard at all, and most likely you won't end up on it when you land."
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nj25ph | why are babies always crying ? Are they scared or constantly in pain ? | Other | explainlikeimfive | {
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"Babies aren't always crying. They cry when they are uncomfortable, for whatever reason, because they don't have a better way of expressing themselves. This discomfort can come from a multitude of reasons - hunger, tiredness, stomach aches, or just general discomfort (maybe they want to be held by daddy instead of mommy).",
"It's not pain that makes them cry. Crying is their only means of \"verbal\" communication. They cry to express any need. They cry when they are hungry, tired, scared, In pain, sick, have a diaper that needs to be changed, want attention, etc. They even cry when the person holding them is not confident holding them, like if they are not use to holding a baby. Any thing they need or want, crying is how they tell someone they need something. Personally this is why I'm not too fond of babies, you have to play the \"guess why I'm crying\" game and I'm not good at it.",
"They have no other way to communicate and are probably super overwhelmed when they want something and can't get it. I mean, imagine not being able to move from the spot someone put you in and having to rely on people who speak a weird language you don't know to get even the necessities. That's kind of what they're going through, in a strange world with things they've never seen before."
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nj2e0p | Why are salmonella cases so low in japan, despite them eating lots of raw egg? | Biology | explainlikeimfive | {
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"They have much higher quality standards when it comes to eggs because they get eaten raw so much. Firstly, they try to minimize the chances of chickens getting infected with salmonella. They have strict hygiene rules when it comes to chicken farming and make sure that there is no contact to possibly infected animals. Then every single egg gets checked by a machine for small cracks in the shell, since salmonella is mostly found on the outside of the shells and that would be a possible way for them to get to the inside. The damaged eggs get thrown away. Then the intact eggs get sterilized. The last important factor is that the expiration date is set earlier to make sure that only fresh eggs get eaten.",
"Because the eggs and chickens they use for these dishes aren't factory farmed. Salmonella is more likely to be present in caged eggs. Also, being the Japanese, I imagine they take great care in cleaning the eggs prior to cracking them."
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nj2rom | What is black fungus and how does it spread? | Biology | explainlikeimfive | {
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"If you are referring to the India news, I got you fam... So, black mold is literally fucking everywhere, it is mainly in our soil and we come in contact with it throughout our lives. No big deal bc healthy adult immune systems will eradicate that shit before it gets going, no big deal. Coronavirus will make the immune system vulnerable.. People in india are not sanitizing ventilators properly and that is how it is spreading over there. I'm really rally high, so..."
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nj2uab | Why exactly does gravity effect time? | Physics | explainlikeimfive | {
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"The modern understanding of gravity (by Einstein) is that gravity is the result of time and space bending due to mass and energy concentration. In other words gravity does not affect time. Bending space-time is what we call gravity. Gravity is a phenomena and a result, not the cause."
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nj3imr | Why is it that when we see or think about something, we see it in other places more? | Other | explainlikeimfive | {
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"You see so many different things daily. A good way to realise this is to just watch a road for a few minutes and count how many different cars you see. You wouldn't pay it a second thought, unless you had a reason to think about specific cars. You've always seen them - you always see most things, things are everywhere - but now they're much more obvious.",
"evolutionary, this helped gatherers find food, having looked at or holding a particular root leaf or berry, they can quickly find and identify the same, to be more efficient at gathering, as well as being aware of predators for the same reason, to avoid being killed.",
"This is called the Baader-meinhof effect. It was always there, you just started noticing it more after you thought/learned about it."
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nj3nt8 | How does the moon produce waves? | Earth Science | explainlikeimfive | {
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"I assume by waves you mean tidal waves, aka tides One of the universal forces in nature is the force of gravity. That is, objects with mass attract each other. This attraction is higher for objects with more mass, and lower for less. Simultaneous, this attraction is higher when the objects are closer to each other, but lower when they are far The moon has quite a lot of mass, not as much as earth, but the moon is the largest mass orbiting the earth. So the moon exerts a gravitational attraction, or pull, on the side of the earth facing the moon. This pull stretches the earth a bit, but the largest stretch we see is in fluids, so water in the oceans. This creates a tide facing the moon. But remember, the gravitational attraction is lower the farther you go. So the ocean/water on the far side of the earth, the side facing away from the moon, feels the least attraction from the moon towards the earth. So the stretch is highest near the moon, medium in the middle, and lowest on the other side of the earth, creating an oblong shape with two tides on the opposite sides of the earth (with the earth itself in the middle) There's also quite a bit more to it, but that'll require too much text, so I've linked a nice YouTube video explaining it here, URL_0"
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nj40rl | Imagine how much money and resource is spend shipping water around the world just part of everyday products. Why can we buy products then add the water at home? | Economics | explainlikeimfive | {
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"Many things containing water cannot be isolated from the water and have their desired properties simply by reconstitution. These could be complex solutions involving chemicals \"dissolved\" in oil plus chemicals \"dissolved\" in alcohol and the parts dissolved in water. Food products, for example, are a complex mixture of the above. Another method would be concentration and dilution. But this is also very problematic because many things are simply too dangerous when concentrated. A dilute acid cleaning product cannot simply be concentrated and sold, for example. Highly concentrated acid is too dangerous to handle. In general, technology and businesses are not silly. They recognize the issues involved and would definitely want to save costs. Examples are that most sodas are bottled locally - the local manufacturers buy a syrup, dilute and pack it locally to reduce costs. If you want to know more, you have to be more specific. What particular \"water\" products are you thinking of?",
"Because much of it would taste like shit. Vegetables, meat and so on would lose its texture and taste like rubber. Much that can be rehydrated is allready transported as dried goods.",
"Not an expert here but a lot of this is already on the market. Tide pods come to mind as a concentrated product to save on transportation and packaging. Also Jello, Gatorade and Tang orange drink all come as powder and you mix it up yourself. You can buy it ready to consume which is much more convenient for kids and higher chance of a mom buying it for her kids since she won’t have to labor to prepare it. This is part a larger issue like why people buy frozen dinners when buying fresh produce and meat is healthier and less expensive"
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nj4i9c | Why is it that about middle age our bones sound like they “crack” when bending, doing push-ups etc? | Biology | explainlikeimfive | {
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"Middle age? I've had that since I was 12. It's little gas bubbles in the fluid in the joints. Completely harmless.",
"Afaik it's nitrogen build up in the fluids that sit between bones. Nitrogen escapes and that's the pop you hear. Why it increases with age is not something I can fully comment on, but I'd suspect it's due to increased wear and tear in the joint allowing for easier nitrogen escape. Feel free to correct me, internet people.",
"Push ups? How about every time I move. My knees especially",
"Most of the gas release has been mentioned. But another is how ligaments and tendons hold joints in a stable range of movement. The cruciate ligaments of the knee are the easiest example - cross your middle finger over your first finger, tightly. Place that on the inside of your knee. That is how the ligaments here are arranged - twisting across each other in order to create tension / torque that stabilizes the knee [so your knee can still bend and extend, but doesn’t move laterally because the shearing would be damaging to the joint]. If you walk with your toes pointing out, these crossed fingers [ligaments] essentially unwind, to some degree. This introduces a lateral [from the side, to the side] force to each step you take. In addition, just like two tightly suspended ropes, shearing forces [scissors IRL] are much more effective at fraying the ligaments and creating damage. So why the snap or pop sound? Your ligaments pull towards this twisted position to create stability, if they quickly unwind, often that ‘snap’ [like rubber bands] is what you’re hearing. It’s also why some joints can be popped repeatedly, which wouldn’t account for many cases were gas buildup the sole source of pops. Last thing - your joints alternate between stability and mobility as you up the body. So, ankles - mobile; knees - stables, hips - mobile; lumbar spine - stable; thoracic spine - mobile; etc etc Mobile joints tend to pop via gas Stable joints tend to pop from unwind Hope that helps! :] Edit: clarity"
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nj55qa | what is the reason for goosebumps when listening to songs? | Biology | explainlikeimfive | {
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"Goosebumps is leftover from when our ancestors were covered in hair, and when they sensed a change in their surroundings etc their hair would stand on end to make them look bigger (many animals still do this eg cats). When we hear a song that we like it triggers emotions within us that our brains/body see as a change in our surroundings/environment and we get goosebumps/tingling on the back of the neck and/or arms were our hair would've stood on end. This is one theory of evolutionary psychology so other people may have different explanations or ideas."
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nj56tw | Why does drinking warm water reduce spiciness in the mouth? | Biology | explainlikeimfive | {
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"Capsaicin (the hot pot of peppers) is kind of waxy, which is why it sticks to the tissue in the mouth or on the skin. Warm/hot water can loosen this bond, allowing the heat sensation to dissipate. Ironically, though, taking a warm shower after being pepper sprayed (or sprayed by other chemical irritants) also loosens this bond. The big difference, though, is that it allows the irritant to bond elsewhere, spreading the sensation"
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nj5prg | - How do clothes get dry when hung outdoors in winter? | (The same question could apply to any pool of water that evaporates in relatively cold weather.) I understand that water evaporates at the boiling point but I don’t think clothes ever get that warm even in direct sunlight. Thank you. | Physics | explainlikeimfive | {
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"Google; Even at low temperatures, there are some water molecules are have enough energy to escape and that's why evaporation in water can occur at any temperature (yes, even if the water is in ice). When the temperature increases, there are more molecules with higher kinetic energy and thus, more water can evaporate",
"Temperature is not what stops water from boiling, it is air pressure compared to vaporization pressure. The vaporization pressure depends on temperature. Water evaporates at lower temperatures than the boiling temperature, it can in fact evaporate at all temperatures it is a liquid. The name change so sublimation went is is solid but is still occur. The rate is temperature-dependent and if there is a net loss of water depending on the moisture level because water condensates too back to a liquid, so a net loss of water depends on the relative humidity of the air. A simple demonstration that is not temperature is to put room temperature water in a vacuum chamber and is start boiling with the pressure get low enough. The boiling requires energy and that results in the temperature of the remaining water dropping. The boiling will continue until the remaining water has frozen to ice. The Ice will sublimate, go from a solid directly to a gas but the rate is quite low. The energy requires for water to become a gas is almost identical at 100C as at 25C. It can be determined by measure the temperature drop of the water. It is this energy that water on our skin takes from our body that is the reason you can cool yourself down by sweating. The rate liquid water becomes a gas does depend on the temperature, at the same time water as a gas will condensate back to a liquid. Let's take a container that starts with a vacuum and fill half of it with water. It should be disconnected from the vacuum pump but it should have a pressure gauge. The result initial boiling but then you get an equilibrium where the evaporation rate is equal to the condensation rate. You now have liquid water on the bottom and water as a gas on top. You can measure the pressure of the gas and if you heat the water the pressure increase. When you 100C, 212 F the pressure will be 1 atmosphere, this is not a coincidence. At room temperature, the pressure is at 3% of an atmosphere. If you do not have an enclosed container the same process will occur water evaporates until the amount of water in the air is the same as in the container. If the air is not replaced with dryer air you have an equilibrium and the amount of liquid water remains constant. But air can move and if it is replaced with dry air the water will continue to evaporate until the liquid water is gone. So water will evaporate at all temperatures where it is liquid. When it becomes ice it will still become a gas but that is sublimation. The rate of evaporation, sublimation, and the amount of water that can be in the air is temperature-dependent. Let's look at boiling without a container. If you look at water that boils you see bubbles forming in the walls of the container and they rise to the surface and disappear. These are bubbles of water as a gas that are formed on nucleation sites, that is irregularities on the container or anything else where water can form bubbles. If water would start to form a bubble and the vapor pressure is less than the atmospheric pressure the result is that the will be compressed back down to a liquid. If the pressure of the gas is the same or higher than the atmosphere then the bubbles will support themselves and can grow, detach and rise to the surface where they can escape into the air. The gas that leaves the water will because of the pressure be able to push away the air. The result is that water can evaporate at a high rate in bubbles in the liquid as long as the temperature is high enough. This is what we call boiling. So it is not temperature directly that is required, it is vapor pressure versus atmospheric pressure. You can boil water in an enclosed container too. A pressure cooker is a pot with a lid and a valve that open as a set pressure. The result is that the boiling temperature of water increases. The pressure is generated by the gas the water release. The same way the boiling water at high altitudes occurs at a lower temperature because of the lower atmospheric pressure. So water will evaporate as long as it is liquid. If you lose liquid water will depend on the moisture level of the air. At 100% relative humidity you will not lose liquid water as long as the water is not boiling Boiling is not directly a question of energy or temperature but one of vapor pressure and atmospheric pressure. The vapor pressure does depend on the temperature. So there is a connection between temperature and boiling but it is not a question if enough molecules have enough energy. If that was the limiting factor water would not boil in a vacuum chamber at room temperature",
"Water evaporates when individual molecules gain enough energy to break free of the rest of the liquid. Individual molecules don't have a temperature, they just have energy. Temperature of something is basically just the average energy of it. So while the temperature of a pool of water may be well below boiling individual molecules are going to be hit by photons or whatever and gain enough energy to leave the water."
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nj5xju | Why do my Cheerios in milk act like magnets with different polarities causing them to repel or attract each other? | Physics | explainlikeimfive | {
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"Milk likes milk more than it likes air. When a cheerio floats on milk, it has milk in/on it, which attracts* the other milk molecules and pulls them up. You can see the surface of the milk curves up to meet the cheerio. When you have 2 cheerios, the curved parts like each other more than they like air, so they behave like magnets. * I'm not sure if \"attraction\" is the right word here, it's more that the milk is taking the path of least resistance. URL_0",
"If you look closely at the side of the bowl, you can see that the milk clings to the side of the bowl and climbs up a small amount. The milk clings to the side of the Cheerios as well. Because Cheerios float, they want to be at the highest point of the milk, which happens to be along the edges of the bowl and near other Cheerios where the milk level is slightly higher due to it clinging and climbing. [This short video]( URL_0 ) has some good visuals.",
"Because each individual Cheerios piece is meant to sink, but they can’t get through the milk’s surface *tension* (assuming it’s a dairy milk). Thus, the milk’s surface molecules direct pieces of Cheerios to “stick” to each other. It’s fluid mechanics/physics at work.",
"Isn’t this adhesion and cohesion at work. The same thing that helps water creep up soil and not stay at water level. Water likes to stick to itself on a small scale. It has to do with the tension held by water droplets and it’s want to absorb into other materials."
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nj622y | Melting Pot | Other | explainlikeimfive | {
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"This analogy comes from metallurgy. You can make new metals by putting other metals in a melting pot and then heat it up until they melt and fuse together. For example tin and copper makes bronze which have completely different properties. Iron and coal makes steel and steel and chrome makes stainless steel. So when we say that a place is a melting pot we mean that it is made up of people from various different cultures which when combined forms an entirely new culture that is different from all the originating cultures.",
"Actually, in Canadian schools we were explicitly taught that Canada is NOT a melting pot. It is a ‘cultural mosaic’, which suggests that immigrants are not forced to assimilate into a homogeneous melting pot, [United States], but rather can maintain their culture and identity to some extent, like individual tiles that make up a beautiful mosaic mural when you stand back. The Canadian government actively funds multicultural and ethnic support agencies that celebrate positive aspects of the old country’s culture through festivals, etc. This is part of the ‘America bad, Canada good’ culture war brainwashing-inferiority-superiority complex.",
"I'm Canadian. I was taught the US is a melting pot because people come from other cultures but they become American. In Canada they come from other places and retain their homeland culture. So we're like a fruitcake."
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nj701j | Why do we feel sick when we see gory stuff like mutilation and etc? | Biology | explainlikeimfive | {
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"It's your body going into shock\\fight\\flight. You see someone severely hurt and your brain wants you to get the fuck away from whatever caused it. It's basic survival instinct. It can be overcome though. Learning field medicine kinda desensitized me to gore. See it enough and you can reprogram yourself to have a different reaction to it",
"My understanding on that is that brain sees mutilated corpse and thinks \"Shit! There is some danger nearby. Drop all the excess weight and prepare to run\""
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nj7597 | Why do mothers enjoy the scent of their babies feet, breath and skin? | Biology | explainlikeimfive | {
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"Its a biology failsafe so mothers wont kill their children when they get annoying. There is a condition that makes these smells irrelevant to the mother, called postpartum depression."
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nj7vps | I’m told skin-to-skin contact leads to healthier babies, stronger romantic relationshipd, etc. but how does our skin know it’s touching someone else’s skin (as opposed to, say, leather)? | Biology | explainlikeimfive | {
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"Others in this thread have mentioned how difficult it is to prove the healthier babies/ stronger relationship aspect of the question. But - your skin **can** tell if it's touching someone else's skin. There are an entire class of sensory receptors in the skin that respond best to soft pressure, **skin temperature**, slow movement touch - essentially being stroked (called Low Threshold Mechanoreceptors) To be a bit un-ELI5 this is called affective touch and neuroscientists are only recently discovering its receptors and pathways in the nervous system. The theory goes that if the body can discriminate human contact using these receptors, it can then release the chemical oxytocin to re-enforce that personal relationship. e.g. between a new-born child and the mother holding it. URL_0",
"Taken from a psychology standpoint, it could have nothing to do with the fact that it is just \"skin\", but more to the point that close physical contact with people you care about nourishes a more accepting and mentally healthy environment. Albert Einstein was quoted as saying \"The single most important decision any of us will ever make is whether or not to believe the universe is friendly.\" This one small distinction made early on plays a major role in how we take in and interpret information from the world around us. What chemicals are released in the brain during close physical contact with loved ones. Just physiologically, hugging someone and other forms of nonsexual touching cause your brain to release oxytocin, known as the \"bonding hormone\". This stimulates the release of other feel-good hormones, such as dopamine and serotonin, while reducing stress hormones, such as cortisol and norepinephrine. All that being said, this may explain why it does feel so good to sit on a leather couch. Subconsciously triggering chemicals related to those mentioned above.",
"Just echo here what others have said about the benefits, but also: Skin and leather are very different. The skin of another person is often warmer than leather (if your couch is warmer than your SO, you may have a problem), has a much higher moisture content, and has an elasticity, softness, and shape not typically found in leather goods.",
"We don't know. But many things like smell, temperature, and sounds of your heart appease the baby. Does it have a long term effect ? Surely, but to what proportion ? We don't know. IMO the data is biased because people who do skin-to-skin contact are people who care about their babies more than people who don't do it. People who care more about their kids lead to healthier development for those kids, statistically. So I think those kids have a healthier life because their parents care more about them, not because they had skin-to-skin contact when they where born.",
"Any time a creature is within close proximity to another living being it will produce oxytocin, more so with same species. Also reduces cortisol levels in humans. So our bodies reward being next to life. Leather or a dead body won't generate the same response because the signs of life aren't there. Warmth, movement of breath, heartbeat, etc. Our skin can pick up a lot of signals our conscious minds don't read. our bodies absorb all sorts of data filtered by the brain. It knows if its live skin versus leather. Edit: changed increases to reduces. bit of a typo there. Also, first paragraph is easily found data that was already assumed in the question. The rest is my personal analysis of data, drawing from acquired knowledge and experience.",
"It helps keep the baby warm and in a regulated temperature, to normalize breath, to soothes the baby, encourages milk production, leads to lower rates of hypoglycemia and stabilizes the baby´s vital signs this is caused by the release of oxytocin also known as the \"love hormone\" which make the mom warm and cozy providing the benefits mentioned above. Theres also other benefits for both the mom and baby that I didnt mention.",
"I witnessed this first hand. My daughter was born 8 weeks premature, she lived in an incubator for the first 3 weeks of her life Wife was really struggling to express breast milk manually or with a pump, we had to feed baby through a pipe up her nose. we couldn't touch her for the first few days it was awful. Seeing wife being hard on herself a d feeling like she was a failure because she couldn't express milk. At the end of the first week the docs said we could hold her for a few moments and they suggested mum does skin on skin contact with her. They placed baby on my wife's chest, baby was all but naked (except for diaper) wife was bra-less. I'm telling you hand on heart it was the most magical thing I've ever seen. Baby immediately started \"nuzzling\" looking for boob/nipple. Mum gave it to her, she tried, wasn't very successful but still it helped. Fast forward to next day, my wife's boobs were literally leaking milk, like her tops and bras were soiled with breast milk. Expressing was now effortless and baby was now getting enough milk to satisfy her and she made fantastic progress. The docs said skin on skin triggered a hormone in mum and caused her to produce milk in larger quantities. So yes, I 100% believe it's a thing.",
"I find this thread fascinating. I was adopted as a baby, and was premature so spent the first 3 months of my life in an incubator with basically zero human contact (the tech for preemies was pretty rudimentary back then, and they didn’t have baby hugging volunteers like they have now). I have an extremely hard time with touch/romantic relationships (I’m in a long term relationship but have never been touchy-feely at all, which others find weird for a woman…). So I’d love to see some peer-reviewed studies that may explain if there’s any connection here or if it’s pure coincidence.",
"I've read the top comments and seems this is unproven but plausible... I'm a dad and when my two sons were born I did skin to skin with them. It felt kind of stupid, there are people coming in and out of the room all the time, I had no idea if it was doing anything... But if we have another kid and there's a 0.0000001% chance me doing skin to skin will have some benefit I'll stop wearing any clothing on my upper body right now if I have to. There's no downside. At worst I look like a bit of an idiot. I'll take that.",
"Your SKIN doesn't know anything. It's a sensory device. It sends various sensory input to your brain, and your brain knows you're touching another human, and that's where the magic begins. And how does your brain know? Cuz it's a brain and it's smart.",
"I don't care what anyone thinks about proving anything. After being diagnosed with an autoimmune disease it wasn't until I moved in with my fiance at the time and began sleeping next to him that I stopped having the majority of my symptoms. You will never convince me there isn't a link between touch and health including stress or just sleeping in the same close to another person you love even if there's not constant touch. There has been a few incidents of newborn babies that were born premature and were said to die soon after birth that had one-on-one skin to skin time with their mom for hours and ended up living. Just like there isn't an exact science that got instinct you have on some things wrong with a loved one or yourself. That instinct that tells you do not go around that corner or do not go to the party that ends up being correct, there isn't an exact science to everything.",
"It's not what your skin knows, it's what _you_ know. Even an infant human has quite a lot of brain, and you don't actually have to be that intelligent to be able to instinctively distinguish being held by another person skin to skin from being placed on a leather surface. It's not merely about texture or whatever, it's about sound, smell, and especially all the little behavioral cues that get passed between a baby and someone holding it.",
"There's this interesting irony that we think of a \"holistic\" \"mind affects body, body affects mind\" attitude as the woo woo spiritualistic point of view, when really, the notion of the body as a dumb machine and the mind as something completely separate sounds a lot more supernatural to me. Our central nervous systems assemble multi-sensory summaries below the level of conscious awareness or control. Have you ever seen those clips of a person speaking with one audio track, and then another, and their lips seem to almost miraculously sync up with either track? This is because we're never conscious of our raw sensory input, it's 90% interpretation by the time it reaches the conscious level. Reasoning mostly informs how we *interpret* these blobs of information, not so much how they're assembled. So yes, we don't have an explicit \"other person's skin\" sensor, but even as babies we instinctually assemble impressions from scent, sight, hearing, and touch that makes us deeply aware of the presence of another person. It's not infallible, but there are a lot of things that even a baby's brain uses to tell they're being held by a person instead of lying on a warm leather coat. If you're interested in a book that touches on these kinds of subjects, on a level in between ELI5 and Ask-Science, I really liked How Emotions Are Made by Dr Lisa Feldman Barrett.",
"There was a study in the past with caged monkey. There was a wire money that can be triggered to give food and a soft furry monkey that didn't provide food. The monkeys would quickly get food from the wire monkey and hang out and cuddle with the furry monkey most of the time. This shows the importance of touch and nurture for humans some animals.",
"Warmth. We've figured out how to simulate the effect, and we even sell it as pet toys with one idea taken from rumble strips in video game controllers, and combined with what's basically an electric blanket. Heartbeat simulation from a warmed source imitates the effect, we use it for underage kittens when they have to be separated from their mothers. I don't know if we use it for babies, if not, we should. That said, it's still an imitation, but it seems to be good enough to provide some benefit.",
"I’ve been sleeping in our other bed cause the dogs take up too much space for me honestly. But I went and slept in the same bed as my gf about month after and literally felt a bonding chemical being released it was weird, and woke up happy and feeling good. From 1 night of cuddling and sleeping, crazy. Fucking dogs haha",
"There is a sense parallel to the basic touching sense, that tells our brain when we receive tender touching, like a hug or stroking. This can't be reproduced by touching yourself, but it can be simulated by machines. I reacts a lot to a specific range of pressure / speed of the touch and can then lead to the release of oxytocin - if the brain thinks the context is okay. A stranger on the street won't be able to give you an unexpexted dose of cuddly feels, as you'd probably just perceive him as a threat. Source: A recent German documentation, so I'm not sure if I should bother posting it here :D",
"Our bodies are completely unaware that it's 2021 and there are no predators lurking around. Babies are essentially still prehistoric, let me explain. Right after birth, skin to skin contact helps babies regulate temperature and breathing rhythm by copying mom. We exchange good bacteria through skin to skin, cuddles and kisses and since the first bond we experience is parent-child, we replicate these behaviors in our other relationships down the line because when we did as babies we felt safe and loved. Those evolutionary reflexes also could explain why babies tend to sleep more during the day, to allow mom to gather food without drawing attention to themselves. Babies will require more night feedings, as mom and baby had likely found shelter at night. Their little bodies are hardwired to feel safe while there is movement because as long as they're being carried by mom, they are safe (it also explains why we deposit babies in cribs like they're made of nitroglycerin).",
"It is my understanding that babies that are still very young (neonates being less than a month old, infants being less than a year) will sleep better and develop stronger because skin-to-skin contact will mimic the womb, which is the environment the baby has known throughout development as a fetus. I am not a doctor, or a medical professional, so please don't take what I say to heart as this is only something I've been told. & #x200B; For the mother, skin-to-skin will help release hormones that will aid in a \"let down\", which is where the milk will flow easier and quicker from the breast. It's also generally just a bonding experience and so a baby that feels free of stress will be doing better in just about every aspect. My wife told me this just know: while I write this she's feeding our 4 month old girl. My baby is large for her age, has a full head of hair, and has incredible muscle tone. Yeah, that's a flex, but I attribute her great health to the love we give her. I make sure my child smiles and I hold her constantly.",
"Something that I have not seen in this threat is the concept of epigenetics and how your experiences in life can literally alter your phenotype, that its, the expression of your genes. To simplify, DNA in a cell is not coiled like it is when you think of a typical chromosome. It's relatively loose, but is given structure by proteins that it wraps around called histones. Now, for your DNA to be read and genes to be expressed, there needs to be room for the proteins and whatnot that do this to access the DNA physically. If the DNA is too tightly wound around a histone, or some histones are clustered together, the DNA is not accessible. Different things can cause this, or undo it, but for the sake of simplicity all you need to know is that environmental factors can influence how your DNA is read, and what genes can be used. Think of it like a book, with some pages able to be read, and other pages are stuck together. How this relates to your question is that there have been studies on the influence of parental contact on the DNA on mice. In mice with limited or no parental contact, the sections of their DNA that deal with stress relief and other factors were tightly wound, meaning the rats had a heightened stress response. Meanwhile in the ones given adequate parental contact, the DNA was looser, allowing the rats to have a healthier response to stress. It's thought the same is true for humans, that is, parental contact is needed for healthy gene expression. So an abandoned child's DNA is altered in a way that negatively affects their development. Here's a good source for you, hope this explanation helped! URL_0"
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