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nj7wyf | Why can't we inhale by our nose and exhale by our mouth at the same time ? | Biology | explainlikeimfive | {
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"As the other poster says, you have only one breathing tube connected to your lungs, and under normal circumstances, air going into the tube is going to prevent air from coming out of the tube. There is a technique called circular breathing, where you essentially build up a pocket of air in your cheeks, which you release in a controlled manner for playing a woodwind instrument, while breathing normally with your nose. Doing that, you are able to play a saxophone or similar instrument continuously without holding your breath or getting winded. (See: Kenny G)",
"You have to create negative pressure in your lungs to fill them by expanding the space in your chest. Then you do the opposite to blow it back out. Can’t have negative and positive pressure at the same time. There is something called circular breathing though. It’s pretty difficult. You should google it.",
"Didgeridoo players - \"Am I a joke to you?\"",
"All these people be trying to explain this like you're 30! It's like when you squeeze an empty water bottle and then put the opening under water, and then stop squeezing to let the bottle suck in some water. And then you can squeeze the bottle squirt water out. But there is no way that you can both squeeze the bottle and not squeeze the bottle to both suck water in and squirt water out.",
"Actually there are saxophone (and other instrument) players who learn circular breathing and can play their instrument almost endlessly. It’s crazy to observe."
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nj89m7 | What is the universe expanding into? | Physics | explainlikeimfive | {
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"New space is being created within the universe rather than at any ‘border’ Picture Ants walking on the surface of a balloon, and the balloon gets inflated. From their perspective the distance between each Ant is increasing without any relative movement on their part. Now imagine the Ants are galaxies and the surface of the balloon is the fabric of the Universe. So the universe is creating space in between two points that inflates the distance between them, rather than expanding on the edges and borders into something else.",
"This is a very difficult to understand situation for humans. As far as we can tell, space is infinitely vast. There is no end to it at all, no matter what. But its also increasing in size because everything is moving away from everything else. that's what people mean when they talk about an expanding universe. Its becoming a larger infinity.. Which is fine because you can increase the size of an infinite expanse without changing the infinite nature of that expanse. This makes absolutely no sense to us though, so our brains kinda shut down when we try and think about it. So we use the term \"expanding\" to describe it, because that's a good enough description for most purpose, even though its not totally accurate."
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nj9q6b | How do fish antibiotics work on humans as well? | Biology | explainlikeimfive | {
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"The antibiotics do not work on either fish or humans, that is what is so good about them. They only work on bacteria. The purpose of antibiotics is to kill all the bacteria leaving all other cells unaffected. So you would not want antibiotics to work on humans as that would make us more sick."
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nja46u | What are the differences between hand soaps, dish soaps, and "antibacterial soaps", both in their make up and their efficacy in cleaning hands ? | Chemistry | explainlikeimfive | {
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"Various soaps differ based on their mixture of compounds but ultimately are all made up of a simple formula: **fat + oil with a salt** (usually carbonate), plus some stabilizing/scenting compounds. Soaps work as a \"surfactant\" which helps dissolve away substances that are usually unable or less able to dissolve in water alone (i.e. non-polar substances). As another poster said, soap is inherently antibacterial because the surfactant properties disrupt the membranes of bacteria and other micro-organisms (literally dissolving them). What makes something a hand soap or a face soap are the \"additional compounds\" added to the basic soap mixture or different fats to make it more friendly to the surface it is applied. Soap can, and often does, dissolve some of the natural oil layer of your skin that helps keep your hands moist, which can lead to dry, chapped or otherwise irritated skin with *excessive use.* Detergent differs slightly in its chemical composition. They are usually **longer chains of chemical compounds with surfactant properties (but are not considered fats like in soap)** and these chemicals are mixed together in industrial-grade mixers, heated up, then cooled and diluted with certain quantities of water based on their intended purpose (i.e. gels have less water, liquid detergents have more water -- **viscosity** differs). These chemicals can be a mix of polar (preferring water), non-polar (hating water, preferring oils), and even ionic (using charges and acid-base chemistry to alter substances on the spot so they dissolve better in it). Detergents tend to be much harsher on skin because they are very strong surfactants -- designed to thoroughly clean your clothes or your dishes and dissolve as much as they can -- and consequently they can completely remove the oil layer protecting your skin. If you've ever gotten laundry detergent on your hands or handled wet clothes enough, you'll notice your hands feel rougher. That's the detergent's effect. \"Antibacterial\" labeled soaps are partially a marketing thing - but they have bactericidal compounds added to them such as triclosan, ethyl/isopropol alcohol, or chlorhexidine. In most cases those are excessive, but some (like chlorhexidine) can leave a temporary protective anti-bacterial residue on the skin after the soap has washed off."
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njcik5 | How was the very first computer able to understand commands? How did they code a system to understand code in the first place? | Technology | explainlikeimfive | {
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"The very first computers didn't understand computer code, they were programmed by hand using a series of switches. The famous Bronze Goddesses used to decode enigma during WW2 were programmed manually in this way. But you could argue they weren't true computers yet, as they were mono-task devices. Programming computers by hand was inefficient and impractical so the concept of the computer language was invented to be able to quickly program computers to perform repeatable tasks. Assembly languages were developed in the late 1940's which were the first computer languages. The computer processors were designed in parallel with the language in the same way that you design a car with a steering wheel and pedals otherwise you wouldn't have a way of driving it. The limits of assembler however is that you need an extremely high degree of understanding of computers and their operation to use it. It isn't practical for anything but the most basic of functions. To make computers do more we invented high-level programming languages that would act as an interface between humans and complex computer logic. Essentially creating a tool that allowed humans to write the logic (a computer program) and then translate it into assembler using a tool called a compiller. The first such language was IBMs FORTRAN created in the late 50's. Higher level languages like C came much much later. The compilers of those languages transform the easier to read code into assembler (machine code) underneath that the processor can understand. Modern languages like HTML, PhP, JAVA etc go a step further in that they produce code meant to be translated by an intermediary program, which in many cases is the browser. The browser in this case is the interface that transforms web code into machine language."
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njcp5r | Why is it harder swimming in deep water | Is it psychological or is there something to do with the increased pressure there is with deeper water? | Physics | explainlikeimfive | {
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"Is it harder to swim in deeper water?",
"It's purely a psychological effect. Water is only affected by what's immediately touching it, it can't tell if there's a sea floor 3 metres or 100 metres below. edit: This is assuming the water is still. If you're in a body of water with moving currents, *then* the depth of the water can have very important effects on how strong those currents are and where."
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njdded | Do things have limited scent/odor molecules? If you leave a spoiled piece of fish out does it stop smelling bad eventually? | Fyi I'm not trying to put off cleaning up spoiled meat, just theoretically do things stop smelling bad? | Chemistry | explainlikeimfive | {
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"It’s mainly bacteria which causes the decomposition of food and the volatile compounds are the ones which stink. So when the bacteria has finished feasting on everything it can the odour would stop too. By then it would be hard to describe what’s left as the original fish, more like leftovers. Edit: I also would think of this for the example of sh*t lol"
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njdj3n | how does my gps determine how long a trip will take? Because I feel that I speed atleast a little most of the way, but the time of arrival never changes | Technology | explainlikeimfive | {
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"Because it is actually really difficult to decrease travel time by simply increasing speed especially in small constant amounts. For example: 10 mile journey 10 mph - 1hr 20 mph - 30 min (saves 30 minutes from above) 30 mph - 20 min (saves 10 minutes from above) 40 mph - 15 min (saves 5 minutes) 50 mph - 12 min (saves 3 min) 60 mph - 10 min (saves 2 min) 70 mph - 8.5 mins (approx) saves 1.5 min) 80 mph - 7.5 min (save 1 min) So once you start speeding say from 55mph speed limit to something illegal, there isn't much time savings unless you're doing something really illegal like 110mph CONSTANTLY. EDIT: There is also somewhat of a \"natural cruising speed\" for highways if there is some traffic. So in a 65mph speed limit highway it is very easy to cruise between 65-75mph constantly and just overtake between gaps etc. But if you try to go at 90mph, the gaps are \"smaller in time\" and you'll constantly speed up and slow down to overtake safely as you approach traffic ahead. So the actual average will be less than 90mph.",
"Your location services already know how fast you are likely to drive on a given road. And the other traffic too, from their phones. It doesn't calculate based on speed limits, but on actual driving speeds and traffic patterns.",
"If you drive an hour at 10% over the speed limit you would have saved 6 minutes. But you can easily spend a minute going through an intersection as you need to slow down from highway speeds, wait for traffic to clear and then accelerate up to speed again. And these times are highly variable so you can easily lose all the time you saved by speeding in a bad intersection. It is not unusual to pass someone driving slower only for them to catch up to you ten minutes later as you wait in traffic. So the GPS predictions are usually quite accurate because you do not really make up much time by speeding.",
"Apps like google maps don't calculate travel times based on speed limits, they base it on how long it usually takes real people to make that trip. You speed a bit, but so does everybody else."
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nje3cb | Why is electricity sometimes deadly? | You sometimes hear that for example a device of 100 volts is not deadly. Only you also hear that people died of a lower voltage. So how does this work? | Biology | explainlikeimfive | {
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"Your body's resistance changes quite a bit. A 50 mA shock through the chest can kill you, but a 50 mA shock through your arm will hurt really really badly but not be fatal so both the path and the amount of current matters You live in a constant voltage world, in North America your wall outlets provide 120V, in Europe they provide 230V, and will let whatever current flow from them that the device wants. The magic equation for this is Ohms Law which is traditionally written as Voltage = Current * Resistance, but since we're trying to find the current we'll use Current = Voltage/Resistance Your skin resistance with dry hands is normally around 100,000 ohms so a 100V supply will only give you a 1 mA shock, you might not even feel it. If you've been outside and your hands are sweaty then you're down to 10,000 ohms and will get a 10 mA shock, you'll definitely feel it but it won't kill you. If your hands are covered in sweat and you've got some fresh cuts on your hand, now you're in the danger zone where your skin resistance is 500-1000 ohms so you'd get a 100-200 mA shock, if it passes through your chest it can kill you. Basically every power source you encounter can supply enough current to do serious damage to you, but we put protections on the ones that have high enough voltages that they're likely to generate dangerous levels of current. In places where we expect you'll have wet hands like the Kitchen and Bathroom we require GFCIs/RCBOs that trip at 5-10 mA to reduce the risk of electrocutions. There are a lot of variables at play with an electric shock. You don't know the resistance of your skin just by looking at it, and you generally don't know what path the current will happen to take. Some people get lucky and get massive shocks that go in their hand and leave their upper arm and just cause internal burning but they survive, others have just the wrong combination and update OSHA's \"Lowest fatal voltage\" number to a slightly lower level.",
"Voltage is what drives electricity \"through\" an object (specifically, a voltage difference). However, current (amperage) is what actually causes damage. Voltage and current are related by Ohm's law, which says that the current flowing through a conductor is equal to the voltage difference divided by the resistance. So you can be in a position where 100 volts can't do anything because the resistance is too high, like if you were to touch an outlet while wearing rubber gloves. But you may also be in a position where 100 volts can be fatal because you've (inadvertently) reduced the resistance, like touching it with a wet hand.",
"It's not the voltage that kills you; it's the amperage. \"Voltage\" refers to the potential difference between two spots; loosely, how \"motivated\" electricity is to move from the higher voltage to the lower voltage. You can think of it as electric \"pressure,\" similar to water pressure in a pipe, if you want. \"Amperage\" refers to the volume of electricity being moved *by* that pressure. Returning to our water analogy, amperage can be viewed as how much water is being moved through the pipe. It should be relatively intuitive that it's the amount of electricity that kills, rather than how much pressure is being exerted on the electricity to make it move."
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njel3h | Why do we mainly see road kill or the occasional pile of bones in the woods while hiking? Why isn’t there more dead animal carcasses just lying around everywhere? Where do animals go to die? | Biology | explainlikeimfive | {
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"Small ones end up in predators. Bigger ones end up in scavengers once dead. Corpse will seldom stay intact for long so you have bones here and there. Bones decay slow but alot of small rodents even gnaw bones for easy calcium. Also big scavengers and predators break up bones. Not to forget, woods are usually big and in comparison there aren't that many big animals in a forest.",
"In the forrest smaller scavangers will tear apart the dead animals and spread the bones over larger areas or take them to their burrows, that's why you rarely find whole skeletons there.",
"Scavengers like vultures, badgers, racoons etc. are very efficient about finding and eating recently deceased animals quickly. Typically they have either great eyes (vultures, storks, and buzzards) and have the high altitude vantage point. Or their sense of smell is good enough to find a carcass over the distance of many many miles. After that insects and microbes make short work of anything else. As to where they go to die...it depends on the situation really if hit by a car well it's not like it was planned, same goes for being predated on. In the case of old age or disease much like how housepets that are dying they find an isolated place that they feel safe.",
"They can be eaten by other animals. But also the woods are very large and what you can see from the trail is very limited compared to what is out there. You also have to consider how quickly organic materials like a dead animal with break down or become unrecognizable. All this together makes a big difference in what you find outside."
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njeqpq | Why are colored pencils so much more difficult to erase than pencils? | Not sure if this fits in chemistry but oh well. | Chemistry | explainlikeimfive | {
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"non-colored pencils use graphite. Colored pencils are a mixture of stuff, but they're closer to crayons than to graphite pencils. Colored wax and materials to make them harder than a crayon and they draw more full colors.",
"Graphite pencils are a solid. The tip is pulverized as it drags across the coarse paper, leaving a trail of solid carbon particles. An eraser will move these around, but more significantly, the eraser will remove layers of paper that contain the graphite dust. You end up with little worms of eraser/paper/graphite. Colored pencils aren’t a pulverizable solid. They’re more like a crayon, made of some sort of greasy material, usually wax. This stuff will stain the paper as opposed to leaving particulate matter on the surface, so the whole process of erasing is a little different. You need to remove much more paper to get rid of the color. Source: uses pencils and erasers. “Crayola Colored Pencils, 12-count”, Crayola Company, 1981. “Dixon Ticonderoga #2 Pencil, Yellow”, Dixon Company, 1979. Edit: added bibliography big thanks to u/data15cool for requesting the references!"
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njet3r | why is it people can hear our phone calls through car speakers but not our music? | Technology | explainlikeimfive | {
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"Cause the volume on phone calls is louder?"
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njewdi | Why do companies spend so much on a logo? | Other | explainlikeimfive | {
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"A brand is the product. Kraft owns Heinz now. If they put Kraft on the ketchup bottle sales would fall through the floor because most people prefer Heinz ketchup."
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njfs58 | What’s the difference between a prediction and a hypothesis? | Biology | explainlikeimfive | {
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"A prediction is speculative. A hypothesis is a question or conjecture, worded in a specific way with the property that is is falsifiable, or able to be conclusively disproven. The scientific method often entails taking questions that we have about nature and reformulating those questions into proper hypotheses, which may then be subsequently tested, and the hypothesis potentially disproven."
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njgipu | If Hitler was austrian, why didn't he fight for austrian nationalism? | Other | explainlikeimfive | {
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"Hitler claimed to be ethnically German. One of the reasons stated for invading Poland was to return ethnic Germans to Germany. The Nazi of being German wasn't just a place of birth but of \"blood lines\" or ethnic history. Really though people like Hitler will use whatever method is effective to gain power, it happened that anti-Semitism and German nationalism is what worked at the time.",
"Because the concept of Austrians was sort of artificial. German nationalism that was borned in 18th and 19th century counted Austria and Habsburg empire as part of land of German nation, after all Osterreich, the name of Austria in German just meant Eastern realm and was refering to a part of HRE.. Austria wasnt allowed to becama part of Germany after WWI, because it was rejected that Austria and Germany could be merged into one after losing the war. Hitler never felt like an Austrian and always felt like a German. Many other Austrians after the war felt like Germans and the new Austrian identity felt forced to them."
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njgnsl | I just read that not drinking milk is not that big of a deal and is maybe harmful for you. Is that true? I thought we need the calcium for our bones? | Biology | explainlikeimfive | {
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"Milk isn't the only source of calcium. & #x200B; A single glass of milk has about 20% of your daily calcium needs. And has about 8 grams of sugar. That means you need to drink about 5 cups of milk in a day to get 100% of your daily calcium. In doing so you would consume 40 grams of sugar, more than of your recommended daily value. A single cup of a lot types of beans has about as much calcium and calories, well as much less sugar and a ton of fiber, protein, and various vitamins. Most of the hype around the need to drink milk was purely marketing on the part of the dairy industry. There is no such thing as a single food that we *need* to survive. But nutrients that can come from 100s if not 1000s of different sources.",
"Eating something high in calcium isn't a guarantee of getting calcium. Your body needs plenty of other compounds and elements to ingest something like calcium. Vitamin D for one. If you eat a healthy mix of foods (dark green veggies, fruit, nuts, pulses and grains) get some sun and drink plenty your body and bones will be in incredible shape. There are some harmful side effects of drinking milk regularly but it's an inevitable byproduct of the beef industry and we utilise it (If you trace back marketing for milk campaigns they originate from the beef industry). Milk on cereal only existed early last century. Our bones were fine long before that. You can see this whenever we analyse human remains. Don't sweat if you want to cut back on milk. You'll be just fine.",
"Milk is not the only source of calcium and you can get it from supplements if you don't consume enough food with calcium. Many nom dairy milks are fortified so it has the same vitamins and minerals as dairy milk."
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njgrk4 | How does a cell phone “know” that a radio signal is specifically for it and not any other phone? | Physics | explainlikeimfive | {
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"We all share the playground, but we know a teacher is talking to us when one uses our name. We hear the teacher talking to others but pay attention when our name is used Our cellphone has an electronic name (identifier) that it uses when talking to towers (which have e-names or identifiers too). While it can hear the tower talking to other phones, it doesn't pay attention until it hears its name. When it hears its name with a instruction that it can follow, it then follows that instruction.",
"Hmm. Not an expert but I have a layman's understanding. Your phone checks in with a cell tower when its in range and the tower routes the call correctly using that information. It doesn't send a call on a frequency and hope for the best, it knows which frequency your phone is resting on and sends a handshake. It doesn't see a cell phone, but a number used to identify the phone on the network, so all the other phones know to ignore the call that are also resting in that same frequency."
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njgtgf | The new Tesla roadster can apparently go 0-60 in 1.1 seconds. What kind of force would that put on your body? That speed honestly seems uncomfortable. | Physics | explainlikeimfive | {
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"60 mph is about 27 meters per second. 1 G (earth gravity at the surface - the force holding you down right now) is an acceleration of 9.81 m/s/s So to get up to 60 mph in 1 second you have to accelerate at about 3G. It's a bit less than a lot of roller coasters, but enough to make you feel like your eyes are bulging. If also happens to be about the maximum acceleration that astronauts experience on launch."
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njgwh2 | How is gravity affected by the size of a planet? | If there was a replica of our earth, but 50% smaller...for instance, would river flow or water falls move differently? Or even rain falling? Blood flow? | Physics | explainlikeimfive | {
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"A planet half the size of Earth would have half of the Earth's surface gravity. It's only has 1/8 the mass (half the size means the volume is 0.5^(3) = 1/8), but it being smaller means only half the distance to the center of mass. Gravity changes by the square of the distance, so half as far means four times as strong. Multiplying the 1/8th of the mass by the factor of four for distance gives us half the gravity. If all the other rules of physics apply, this has huge effects on everything. The biggest one being that the atmosphere goes away because tiny Earth is too small to hold on to nitrogen and oxygen. With 99% of the atmosphere gone, air pressure drops by 99%, and the boiling point of water is now 44^(o)F/7^(o)C. This is kind of a big problem since now liquid water can't exist on most of the surface so there's less area for rain to come from. Once that rain does happen, thing's will be pretty normal just slower. It will fall slower and rivers will flow slower since the low gravity means the water has less potential energy to become motion as it flows to sea level."
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njhglw | What is a short in electronics? | Technology | explainlikeimfive | {
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"Electricity wants to go the shortest path to from the power source to \"ground'. But people put a bunch of lights and chips and stuff in the way and make it go through that all first. It you mess something up and make a shorter path it will 100% take that path and not bother going the long way through all the lights and chips and stuff. Ruining your thing, with all the electricity you needed going a faster way instead of the way you wanted.",
"Electricity is lazy as shit. It really doesn’t WANT to power your lights and stuff. So if you give it an easier route to get to where it wants to go (the ground, normally, think lightning) … it’s gonna take it."
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njhza5 | Why do we feel cold during a fever? | Biology | explainlikeimfive | {
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"In order to understand this, one must first understand temperature regulation in the body. An area in the brain called the **hypothalamus** serves to regulate temperature, much like you have a thermostat to control HVAC machinery. The **hypothalamus** establishes your body's **set point** of temperature - on average, 98.6F or 37C. This fluctuates slightly based on the time of day but is otherwise normal, and the fluctuations are very small and gradual as they change. Fever is known as **hyperpyrexia** in medical language. Using an infection as an example, chemical signals from elsewhere in the body warn the hypothalamus of the presence of infection. The hypothalamus responds by **raising the set point of your body's thermostat** to a level much higher (relatively speaking) than normal -- for example 102.0F (38.9C). However, the rest of the body is still 98.6, and because the hypothalamus \"raised the set point\" quite quickly, the body perceives it is too cold. In fact it perceives it is VERY cold, because it is out of sync with the hypothalamus. The response is shivering (rapid muscle contractions to create heat), extra blankets (to prevent heat loss), and general desire for warmth. All of this will raise your body's actual temperature to the new set point. When your body reaches the set point, you stop shivering or feeling as cold. The hypothalamus may stop signaling for fever and lower the set point back down to 98.6. But the actual body temperature is still close to 102. When this happens, you *feel* extremely hot and begin perspiring heavily to get rid of the extra heat you made to reach the fever set point. \\-- While on the subject, there is a difference between what I said above, and in **hypo- or** **hyperthermia**. In hyperthermia, the hypothalamus is signaling a normal temperature set point (98.6) but whatever activity you are doing or if you are stuck outside on a very hot day has raised your body temperature above the set point. You may be 104 but the hypothalamus is saying 98.6 so you sweat and seek cool beverages. Same is true for hypothermia -- normal set point but actual body temperature is too low. Fever/Hyperpyrexia = hypothalamus changes the thermostat, body has to respond accordingly Non-fever/hypothermia/hyperthermia = hypothalamus has normal set point/thermostat, but body temperature has deviated and seeks to get back to normal",
"Your body can't tell temperature, only a *difference* in temperature. So when you have a fever and your temperature goes up, the room feels cold. Because it's colder than you."
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nji11v | What happens when your nose gets clogged and how can the ‘clog’ move from nostril to nostril? | Biology | explainlikeimfive | {
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"When you have a clogged nose it’s mainly due to 1 of 2 reasons. The first is you have mucus inside your nostril and you’ll just have to grab a tissue The second reason is there may be fluid such as pus building up in the sinuses it’s for the most part air filled portion of the skull and that’s under normal circumstances. However, once irritated it could produce fluid in the area causing it to become clogged. You could actually shift which side is more stuffy if you lay your head down on the left side your left nostril tends to be more stuffy after a few minutes this is because gravity is pulling fluid from the right sinus to the left. Another possibility for the shift is because one nostril may just so happen to have more fluid in that sinus and it can vary the amount of fluid in each one throughout the day.",
"URL_0 scishow why is only one side of my nose working. Nasal tissue is similar to erectile tissue too kinda neat fact. Edit fixed link",
"If you take a flashlight and look at your nose while its healthy vs while you have clogged passages you will notice the path is blocked by what seems to be inflamed tissue"
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nji8dg | Considering that CCTV footage is the primary way of identifying shoplifters, bank robbers, etc., why is the footage for something so important such low quality that you can barely identify a face? | Technology | explainlikeimfive | {
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"text": [
"CCTV cameras can't be recording all the time because high res video uses up a lot of space. So CCTVs use tricks like lower resolutions, temporary shutdowns, and compression to reduce the amount of storage they require. You CAN have super high quality CCTV footage but a lot of businesses don't bother because it's too expensive. Camera systems are often very old and outdated and ostensibly only exist to reduce the cost of insurance coverage. Casinos for example have incredible CCTV setups, while a gas station will have a couple of cheap cameras and a couple TB of NVR (video recording) Catching thieves also isn't as important as you might think. A lot of businesses don't bother with the hassle of catching petty thieves since it's easy to claim the insurance or write-off the cost than it is to pursue in court. Casinos however are very much interested in pursuing and banning cheaters. The stakes for them are much much higher. Footage shown on TV is sometimes also deliberately lowered in quality to protect intellectual property or by-standers.",
"Because high definition footage requires a lot of storage space and higher quality equipment (computers and cameras) that can be very expensive.",
"CCTV mostly reduces crime through deterrence. It causes criminals to commit crimes someplace else. As a result, the imagery isn't really essential, only that there is imagery that can sometimes lead to an arrest. That makes real cameras slightly more effective than fake ones. Spending money to get good information would be much more expensive, do unless you're all in on suppressing your population (Yes, talking about you China) than it's not worth the extra cost to get good imagery."
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njifou | Why do semi trucks and buses always stop before crossing railroad crossings even if there isn’t a train passing? | Other | explainlikeimfive | {
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"text": [
"Because the worst school bus accident in US history was due to a collision between a school bus and a train. In December of 1938, a driver by the name of Farrold \"Slim\" Silcox was carrying 39 students in school bus during a snowstorm in Sandy, Utah. The bus approached a railroad crossing but visibility was poor due to the snow. The driver had never seen a train cross in his 3 years of driving so he decided to cross. A train did come in that day because it was 1 hour late due to the blizzard. The train collided with the bus at 60 mph, dragging the bus nearly half a mile before stopping, killing Silm Silcox and 25 students. Since then, school buses have been required to stop at crossings and open their doors to hear for train horns. No collisions have occurred since the law was passed. Regular buses and larger trucks also follow the same regulations for safety of the passengers, driver, and cargo. A train colliding with the larger vehicles can lead to much more damage than colliding with a regular sized automobile.",
"CLDA Driver of 5 years. Simply put because what if one is passing? It takes about 11-13 seconds for a fully loaded tractor trailer to cross the tracks",
"They have to listen for them, legally. It's an extra step just in case, because it's a long vehicle with so many passengers they're responsible for. Should there be an issue with the signals or trains, they'll be able to hear it coming anyway."
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njjfok | Why does a hot bath make my heart race? | Biology | explainlikeimfive | {
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"text": [
"Hot temperature makes all your blood vessels open up and get loose to try and cool you down. Normally that happens a little at a time, but if you jump in a hot bath all your blood vessels get loose all at once and you have the same amount of blood in way more space so your heart goes \"where the heck did all my blood go!?\" and tries to beat faster to make up for the suddenly lower blood pressure on some sort of assumption you don't have enough blood and need to get it moving faster to live."
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njk9kl | Why isn't nuclear research/development not as big as it used to be? | Other | explainlikeimfive | {
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"text": [
"It kind of lost favor when the US spent decades trying to decide what to do with all the piling up nuclear waste. I think they still haven’t decided, actually. Are they using Yucca Moutain? LPT: Don’t make dangerous waste that will take 50,000 years to become safe if you have no real plan on how to store it for 50,000 years.",
"As others said but also, its super expensive. Building and maintaining a nuclear plant is very expensive. And accidents happen more than just the big ones you hear about. A youtuber called plainly difficult talks about lots of man made disasters including alot of nuclear ones and he has hundreds of videos on the subject. Edit; also nuclear waste can be stolen and used to make whats called a dirty nuclear bomb"
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njkd7q | What is Zero Point Energy? And how could alien ships use this for fuel? | Technology | explainlikeimfive | {
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"text": [
"Zero point energy is the lowest possible energy state of the vacuum, the \"buzz\" of the void. It cannot be accessed or used in any way, no matter how advanced the technology (unless our physics is wrong). A difference in the amount of energy is needed in order to extract some to do some work. Since every spot in the universe teems with zero point energy, there is no differential due to zero point energy anywhere that can be extracted an used. Every point in the universe has at least that amount of energy already.",
"Instead of having no energy like you would expect all empty space has a certain amount of energy by default. As far as we know there is no way to use that energy. It’s everywhere so there is no clear way to use it. It’s a cool way for fictional aliens To power a ship, free energy everywhere!"
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njkiwe | How is it that helium is a rare element needed for X-rays that we will run out of but is used for silly things like balloons and voice modifiers? | Chemistry | explainlikeimfive | {
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"Helium was stored as a government essential gas, however policy changed so that storage was no longer regarded as essential so the store was sold off and people used it for balloons. Helium is constantly being created on Earth, but the gas is also lost to space, it may become more difficult to extract, however it isn't going to \"run out\" URL_0",
"Helium isn't rare. You can extract it from the atmosphere using a technique called fractional distillation - which is how a lot of industrial gases (like argon and neon) are produced. However, helium is also a \"waste\" product of natural gas extraction. In particular, natural gas from the midwest US contains huge amounts of helium in it. That helium needs to be removed from the natural gas before the gas can be burned, which results in way more helium being produced each year than is needed. This means helium is cheap. Its so cheap, in fact, that very few people bother capturing the helium that they purify out of natural gas. Even though there are tons of sources of helium, there are only a handful of plants that produce it worldwide. This means that you end up with a shortage if one of those plants goes offline. The main plant currently producing helium in the US is owned by the US Government and it will probably run out at some point in the next 10-20 years. Because of that, its very easy to write a sensationalist headline to the effect of \"world about to run out of helium!\" But the world isn't about to run out of helium - again there is tons of helium produced every year, but most of it is just vented into the air as waste. Its not hard to capture that helium. And even if we run out of natural gas, helium is a renewable resource that is easy to extract from the air. All that's happening is that one of the main helium plants is shutting down soon. When that happens someone will open up a new helium plant and everything will remain normal.",
"Helium is not needed for X-rays. Liquid helium is used for the superconducting magnet in an MRI machine. Both MRI and X-ray are medical imaging techniques but they do not work the same way."
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njl31y | If the Sun emits electromagnetic radiation and the Earth is protected by the ozone, how does things sent to space protects itself from it? (spacecrafts, satellites, ISS, astronauts, etc.) | Technology | explainlikeimfive | {
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"Very few astronauts have been at a high enough altitude in space to worry about that too much. 99% of astronauts have only been to low orbits and so are protected by the Earth's magnetic field. The ones who went to the Moon just had to accept a higher chance of cancer and the possibility of a solar storm killing them. For things like satellites, probes, etc the electronics are shielded.",
"Electromagnetic radiation is radio waves, microwaves, infrared light, visible light, ultraviolet light, x-rays, and gamma rays. The sun primarily emits infrared light, visible light, ultraviolet light. The ozone layer blocks most of the ultraviolet light. So the ozone layer is relevant for life on earth that is out in direct sunlight. Blocking UV light is trivial, the aluminum foil you use in a kitchen will block all of it. So it is not a problem for spacecraft. It could damage optical instruments but so the visible part of the direct sunlight. Plastic can also be good at blocking UV light. Typical astronaut helmets use polycarbonate for the transparent part will blocs over 99% of all UV with the tickets used in protective glasses, A astronaut helmet is thicker. So the UV on an astronaut's face during a spacewalk is less than if you are out in the sun on the ground with no protection. There is a radiation problem with the sun but that is the solar wind with charged particles, protons, and electrons, not electromagnetic radiation. The magnetosphere protects the earth from most of the and ISS is inside the magnetosphere. That is one of the problems for astronauts if you for example travel to Mars."
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njlizs | If your whole body is hot under the blankets at night, how does sticking one leg out from under the blankets reduce body temperature enough to make you comfortable again? | Biology | explainlikeimfive | {
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"One leg has a decent amount of surface area that it can cool down when it's exposed to the cooler air. If you're wondering why one leg doesn't get cold while the rest of you stays warm, that would be blood flow. The leg and the blood in it cool down, and the cooler blood circulates through your whole body, bringing the temperature down. Kind of like opening one window in a warm room - the cool air that comes in the window can flow through the whole room and lower the temperature a bit.",
"Blood vessels in the extremities (hands and feet) are very, very concentrated and close to the skin. If you stick your foot out, the blood flowing through it is able to cool down due to air exposure, and as it circulates, serves to cool your whole body.",
"Birds do it too. They sit/stand on one foot so they can get the rest of their body warm. They tuck their foot into their feathers to keep warm.",
"By dangling an exposed limb away from the safety of the covers, the monsters under your bed stop heavily breathing on the underside of your bed (which normally heats it up), and instead project their hot breath into the room.",
"Strangely enough it might not actually cool you. I don't remember the specifics but years ago I read about a experiment that put people in a very hot room but half of them had about a square inch of skin on the inside of their wrists cooled by a special cooling device. Those with the cooling device self-reported much less heat discomfort despite no significant difference in body temperature. I'll see if I can find the experiment but I'll probably forget. Edit: I think it might have been [this experiment]( URL_0 ).",
"I see a lot of comments focusing on the body circulating colder blood but I feel like there’s an easier explanation and it’s simply that by sticking one foot out, you’ve created another opening in the blanket for hot air to escape from."
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njlso8 | How do birds not die on power lines? | Other | explainlikeimfive | {
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"text": [
"The birds are not conductors unless they touch two power lines simultaneously or touching something else that is grounded."
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njm13k | Why/how do pills expire? | Chemistry | explainlikeimfive | {
"a_id": [
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"text": [
"Chemicals react. With air, with each other, with other chemicals…so while many pills will not become toxic, the active ingredient might degrade and not be as effective.",
"Pills are exposed to varying degrees of heat, light, water vapour and oxygen all of which can cause a chemical reaction to take place in medication rendering either the pills ineffective or in the worse case toxic."
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njmito | If the frequency of light determines its energy, what is the role of amplitude? | Physics | explainlikeimfive | {
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"text": [
"The frequency determines the energy *of one photon*. The particle explanation would be that the amplitude of the light gives the number of photons. Basically, it's how bright it is.",
"Using waves to describe light is a way of putting it the physics of light into other physics we understand. In a sound wave, the frequency determines the specific pitch, which is similar to how the frequency of the light wave corresponds to a specific perceived color. Like a sound wave, a higher amplitude means higher **intensity**. For sound, this means louder. For light, this means brighter. This video has a good example of light coming out of a phone's flashlight to show intensity: [ URL_0 ]( URL_0 ) where the light on a piece of nearby paper is more intense than the light when you move back and it hits a larger area of the paper. This is because Intensity (or brightness) = Power/Area, so when you increase the area and keep the power of the light the same (the flashlight isn't changing power), you see lower intensity. What is power, then? Power is the amount of energy transferred over a specific period of time. So not the energy of a single photon, but the energy of *all* the photons that hit the surface where you're measuring the light's power. This actually does relate back to energy: if you have a higher amplitude incoming light at the same wavelength, the higher intensity means more power. Higher *power* means more energy *being transmitted* over the same length of time. So, with light of the same wavelength, **higher** **amplitude** means **higher** **power** means more photons (of roughly the same energy each) hitting that same area, which we **perceive as** **brighter**."
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njmofv | How do we know that smaller Hominid species like Homo Floriensis aren’t just misidentified juvenile members of other Hominid species? | Earth Science | explainlikeimfive | {
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"text": [
"You can tell people are still growing by if their bones are fused or not. For example if the femur is still growing the caps wont be attached, if they are attached you know they've reached their adult height for that bone.",
"Checking for growth plates in the skull, position of wisdom teeth, bone loss etc can give you a fairly decent idea of how old the bones were when they became no longer live tissue. Apes have known growth/ loss rates for healthy individuals. Poor nutrition, extreme prolonged stress can skew these results, but teeth composition can give you an idea of nutrition condition to rule out variables there. Overall bone composition and environmental data can give you an idea on environmental stressors to rule out variables there."
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njoeyz | How do anthills get formed? Where do the ants stay before/while they build it? | Biology | explainlikeimfive | {
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"text": [
"An ant hill starts when a newly fertilized queen lands and starts digging a hole for herself. When digging, the dirt doesn't just disappear, it pile up around the hole she is digging. Later her babies hatch and some of them start to take over the job of digging. Again, they dig some dirt from the walls of the chamber they are making. Then they dump it outside. The dirt piles up, forming an ant hill.",
"They go underground and make tunnels. The dirt if the anthill is what they've removed from underground to make the tunnels. I got my kid an ant farm a few years ago and it was fascinating to watch them do this!"
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njp0lv | A quick google search yields that the human eye can see 30-60 FPS. Why is a 144hz or 240hz monitor visibly smoother if the eye can only see less than half of the frames? | Biology | explainlikeimfive | {
"a_id": [
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"text": [
"The reason for that is simple. What you found on google is wrong. Much of what you can find on the internet is wrong. Most of it is not written by experts but instead by just anyone who wants to voice their opinion. You can find all sorts of incorrect information on the internet. And cat videos.",
"Your Google search is incorrect. The human eye doesn't see in any specific frame rate, or even really in any specific range of framerates. Think of it like this. If you watch a video of grass growing, it doesn't really matter if your video is at 10 fps or 1000 fps, because not much is changing, it'll appear pretty smooth. Contrast this to playing a high octane shooter like Doom Eternal or something. In that context, not only are you taking in large amounts of changing visual info, you're also processing auditory info, and having to actively move a character around. These other factors contribute to being able to notice higher framerates. They'll all still process as continuous movement, but higher framerates will be more smooth. But because human senses are limited, you get diminishing returns the higher you go."
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njq2ia | Is ECMO basically like dialysis for the heart? | Biology | explainlikeimfive | {
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"text": [
"Similarities- They replace the function of an organ imperfectly to buy time for a permanent solution. Differences- Heart functions are needed constantly. Kidney functions can be left for a few days while still living a mostly normal life in between dialysis appointments. While I think it's commonly a mistake, dialysis can be performed indefinitely without seeking a transplant. Patients can survive for decades on dialysis, the longest ecmo patient is a less than two years and not getting an infection over that time is a minor miracle. So yes and no."
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njqdf7 | Why does salt water dehydrate you, but saline/sodium chloride/electrolytes hydrate you? | Chemistry | explainlikeimfive | {
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"text": [
"It's the concentration of salt that's key. Saline is .9% salt while ocean water is 3.5-3.8% Your body needs a small amount of salt to function, but Ocean water has so much salt dissolved in it that it overloads your body, so your kidney's have to filter it all out which in turns uses up more water than you put in.",
"If you drink Salt water like Sea Water then your body now have too much salt, in order to get rid of it your body uses its available water in your system to pass it through the kidneys and kick it out therefore leaving you dehydrated. Normal water on the other hand has very minute and necessary amount of salts which is exactly what our body needs to function and it hydrates us. Also, pure water as in 100% H2O or commonly known as Deinionized water is also going to leave you dehydrated as such water have absolutely zero salts. Such water will draw out salts from your system leaving you dehydrated. tldr: Both Salt water and Pure water (with zero salts) are bad and will leave you dehydrated."
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njrbow | Why does Listerine leave a burning sensation sometimes? | Biology | explainlikeimfive | {
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"text": [
"Listerine contains alcohol (unless you buy the no alcohol version). Note: it's a kind of alcohol that's very difficult to get drunk on . Alcohol makes your body's temperature sensor cells more sensitive. So they detect your own body heat as a burning sensation."
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njrnd9 | Why can’t we live forever? | Biology | explainlikeimfive | {
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"As you get older your DNA is more prone to having errors when it copies itself. These errors eventually lead to you being more susceptible to diseases. There is research being done on how to prevent the degradation of DNA",
"Because your cells are programmed to self-destruct once they divide enough times. There's a big book hidden inside you. Every cell has a copy, and when your cells make more cells, they make another copy. But the book's instructions for copying the book includes tearing out and crumpling the last page in the book. The book has a bunch of blank pages in back so it's not a big deal. But once you're old enough, you run out of blank pages and important stuff starts to get destroyed. (Your brain is fine, those cells don't often split. Your skin splits a lot.) This isn't universal. Lobsters and some jellyfish simply don't do this. But lobsters get so big that they can't molt, and they die from that if they get too old. They're working on adding more pages to the back of all the copies of the book inside you, as well as yoinking the parts of the Lobster's book. After that, cancer is the next big hurdle, but whales have a robust system of dealing with cancer.",
"If I recall correctly 2 big reasons. Finite amount of brain cells after a certain age. DNA strands lose bits off the ends every time they replicate as you get older, eventually they are non-functioning or they become prone to errors/mutations that cause health problems.",
"Evolution . Some animals actually can live forever technically because evolutionary wise that made more sense . Unfortunately mammals went the course of heterosexual procreation . The fact we have children is why we can’t live forever . In nature living things tend to evolve into the best option for survival . Our ancestral lineage unfortunately found it easier to procreate and have children for our continuation versus just having the living thing live forever . It sounds abstract but it makes sense . Natural selection basically screwed us . It for whatever reason was easier for our ancestors way back to just have offspring . Technically our children and their children ....etc allow our DNA to live forever so we sorta do",
"Aside from cancer cells, all cells in the human body can only divide a certain amount (aka the hayflick limit) and once you hit that number you're screwed. See eventually critical cells will go extinct inside of you.",
"Aside from what else is mentioned here, I'm pretty sure I heard somewhere that oxygen might be a cause. Not THE cause, but one of them. The only example I can give you with my limited knowledge probably isn't even correct, but it has to do with something like iron. It rusts when exposed to oxygen. I'm sure there are better examples, but like if oxygen does that to iron, what might it be doing to us even though we need it to live? Another thing I've considered is that we're carbon based (I think??). You can probably get spiritual and be like \"everything burns out eventually, some faster than others.\" We need to engineer a being made of plastic, since that stuff is going to last millions of years. Then we'll \"live forever\" in a sense."
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njry7m | Why when you have a fear of something, the anxiety makes the fear feel like it will happen? | Other | explainlikeimfive | {
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"Anxiety is a survival instinct, it's there to make you hyper-aware of danger if you think you're at risk of being attacked by a bear or something. If you're in a situation you know to be dangerous, anxiety will put your body into fight-flee-hide mode. This is great if you're in a stress situation that actually has \"real\" danger, like you're in a forest you know bears live in and you want to not get eaten. It's less good in more \"abstract\" stress situations like not feeling confident in your workplace and worrying about being fired and not being able to feed your family. There is *danger* there, but it isn't something you can channel adrenaline into fighting, running, or hiding from because it isn't a *physical threat* coming to get you. In those situations, because the anxiety never gets resolved (the adrenaline never gets channeled into **doing** something) it just sits there messing with your brain chemistry which can result the Anxiety modern medicine would recognise as a mental health issue because you always **feel** like you're in danger because you haven't been able to properly resolve whatever inciting incident made you feel anxious in the first place. This is why it's vital to have mental/psychological coping strategies for feelings of anxiety beyond just fight-flee-hide; the problem is that \"modern\" stresses only arose very recently in human history, whereas all our biological evolutionary history tells us how to fight-flee-hide. We literally have to unlearn that \"panic\" response in order to be able to process modern stress, as modern life is so far removed from what anxiety is biologically \"meant\" to be useful for."
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njt7ue | Why does meat change colour when cooked? | Biology | explainlikeimfive | {
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"Answer: heat makes chemical reactions happen, and happen faster. Myoglobin turns from red to grey when it oxidises. Protein (the muscle fibres) breaks down into amino acids, which react with sugar under heat and turn brown. Fat melts and becomes transparent. Both the red and the brown are the tasty bits, so cooking a steak is a balancing act. Relatedly, Potassium Nitrite reverses and prevents the oxidation, which is why preserved meats usually stay bright red."
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njt8mc | Is there any actual connection between plant-based milks and mammal milks? Or do they just taste similar by chance? | Biology | explainlikeimfive | {
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"People have made the recipe for almond/soy etc milk taste close to cow milk to mimic it. If you just ground almonds and added water it would taste like…ground almonds in water.",
"More like they taste similar because people try to find similar substitutes for mammal milks 🤷🏻♀️",
"Yes, there is a connection, the word milk. In one case, the original use of the word, milk is what it is. In the other case, advertisers and marketers want to *sell* you something that tastes like something else, so they use the same name. It's very similar to *selling* a vegetable as a hamburger; it doesn't need to make sense -- we live in a world where alternate truths abound!"
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njt8zx | Can smoke go to your stomach instead of/as well as your lungs when you inhale from a cigarette? | Biology | explainlikeimfive | {
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"Hell yes. There was always that one dude in high school who smoked pot on break and swallowed when the bell rang, only to have it reappear a few minutes later as a burp in the form of a very incriminating cloud.",
"I'm not sure the exact science behind it, but when I first started smoking, if I couldn't hold a hit down I would swallow the air. When I burped later it would be a little smokey. Same sensation as swallowing air to intentionally burp.",
"No not when you inhale. You'd need to *swallow* and you can't swallow and inhale at the same time (for obvious reasons)."
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njtb8w | Propositional vs. Predicate Logic | Can someone explain the difference between propositional and predicate logic, as well as give a few examples? | Other | explainlikeimfive | {
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"When you did algebra in school, the letters stood in the place of numbers. So when you said x=y+2, x and y represented numbers. In propositional logic, the letters represent propositions, or whole sentences. Hence in the sequent P - > Q, P ¦- Q, the P and the Q represent whole sentences. In predicate logic, the letters represent the subject and predicate of sentences. So we might represent the sentence \"Jo has two legs\" withe the symbols Fa, where the capital letter 'F' stands for the predicate \"has two legs\" and the lower case letter 'a' stands for Jo. Although that's just a convention. It doesn't really matter how you represent things, so long as you are making that separation between subjects and predicates."
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njtbhd | how our brains know to use our organs to keep us alive. | Like, how do they know they need lungs for oxygen? How do they know to send waste to our kidneys? How do they know to always keep the heart beating? | Biology | explainlikeimfive | {
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"They don't \"know\" they are just doing what they are preprogramed to do, if they didn't you would die and that would mean that evolution would remove you from the group of functioning humans."
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nju89e | what is the difference between oil-based, water-based and graphite lubricants in how they function? | Chemistry | explainlikeimfive | {
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"Water does NOT make a good lubricant. About the only thing I can find that uses water based lubricants is sexual lubricants. The lubrication is not provided by the water itself but by creating gel that works similar to grease but in a much thicker layer. Oil is your standard lubricant and works in different ways depending on the specific application varying from where it's only filling the microscopic layers on a metal's surface to providing a full boundary layer such that the two metal surfaces don't meet at all and thus no welding or wear occurs between the microscopic peaks on the surfaces. Without lubrication two metal surfaces will weld to one another under heat and pressure. Oil circulates in a system where as grease (oil + thickener) stays put. Dry lubrication (like molybdenum disulfide or graphite) functions like a grease where it stays put but it has hundreds or thousand of sacrificial layers. So each time the surfaces met a layer of the dry lubricant is taken off instead of wear occurring to the metal surfaces. It's more expensive than purely oil based greases but can be applied on a much thinner surface, used with much higher temperatures and potentially lasts longer depending on the application."
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njw2ft | Saw a video of a squirrel getting rescued via CPR and it made me wonder... If CPR on humans has a specific "cadence" to it that is said to be best, would CPR be more efficient on an animal if the cadence was much faster (to match their normally quicker heartrate)? Thanks! | Biology | explainlikeimfive | {
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"Indeed it is. There have been some research into this on dogs and cats which are the animals most often receiving first aid. And they have found that the optimal cadence is much faster then on humans. In addition the heart is not in the exact same place and the ribs are different so you end up performing the CPR routine completely different on different animals. However doing anything is better then doing nothing so you should not be afraid of doing the CPR wrong. It is also worth noting that CPR does not cure someone from a stopped heart but instead keeps them alive until they can be healed. There are some cases where the body can heal a stopped heart on its own after a few seconds or even a minute or two but in general you should continue with the CPR until professionals tell you to stop.",
"Yes. The cadence is quicker not just in small animals but also in infant humans, also the depth of compression is shallower and breaths are short and sharp. Just little puffs from your cheeks. #CPRSavesLives",
"Correct me if I'm wrong, but chest compressions are intended to mimic a heart beat while the heart itself has stopped. So yeah, performing chest compressions too slowly would be ineffective."
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njw8n8 | why is it bad to swallow large amounts of your own blood? | I was in a car accident as a kid and had to have my stomach pumped from swallowing a lot of my own blood. Why was this necessary? | Biology | explainlikeimfive | {
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"Doctor here, many people are confidently wrong in this thread. Real reasons are : 1) Blood in stomach or vomiting blood doesn’t necessarily mean you swallowed it. It can be your digestive tract bleeding, which would be absolute top priority to rule out or treat. Clearing it is a necessary step to check it with endoscopy (camera probe) if need be. 2) Full stomach is a vomiting and aspiration (choking) risk in a trauma patient, and an anesthesia risk for the same reason. Emptying stomach protects airways and makes an eventual emergency surgery easier and safer. All the comments about iron toxicity are completely absurd. People with any kind of digestive bleeding end up *severely iron DEFICIENT* since the GI tract can only absorb a small % of the iron we eat, so you’d necessarily end up with less iron in you bloodstream at the end of the day. The amount needed to be toxic would require you to drink more blood than you’ll ever have, obviously killing you from blood loss in the process. And even self-inflicted iron toxicity was a thing, when a kid is wrecked and bleeding profusely from a car crash, it would be ridiculously insignificant in the list of things you’d have to take care of in emergency.",
"A) You don't want to add vomiting on top of all the other shit going down. Having a whole heap of blood in your stomach irritates it and makes it more likely. B) You want to know if bleeding is from the stomach or somewhere else if you do throw up. If there's a whole heap of blood from somewhere else you it's hard to tell if there's GI bleeding and that's something doctors really need to know.",
"Update: Holy shit this blew up. Big thank you to the actual doctors in here clarifying things for me. Really appreciate the time!",
"As someone who just 2 weeks ago went through Maxofacial Surgery that went well beyond the predicted 4-6 hours I can confirm that blood in your stomach alone won't get your stomach pumped. I was under anesthesia for almost 9 hours and when I came to I was extremely thirsty despite the I.V. I was hooked up to. My wife gave me a syringe full of water, which is not a lot, but as soon as it hit my stomach the hospital room turned into what I can only describe as a murder scene. I had about 5 seconds of warning to tell the nurse I was going to be sick, which was odd for the little amount of water I had drank and being fasted for almost 48 hours. The nurse was scrambling for a trash can when I started exorcist vomiting all over myself (mouth wired shut), the floor, and anyone that was within 5 feet of me...it was all blood that had ran into my stomach during the surgery.",
"Honestly, the most real reason is because blood in the stomach (assuming you drink it???) makes people nauseous and vomit. Vomiting is not good because it increases the risk of aspiration. Lots of people swallow blood from things like nosebleeds. It's no big deal other than it can make them nauseous. I have been an Emergency Medicine physician at multiple hospitals within the US for the last 12 years. Trauma level 1 and 2, Peds/Non-Peds, etc. I have NEVER EVER had to \"pump someone's stomach\" for a trauma. This is just NOT DONE in modern Emergency Medicine. (I have intubated innumerable trauma (and non-trauma) patients and all of them get an OG tube post-intubation. This is normal post-intubation protocol to prevent aspiration. This could be what you are referring to, but may have understood incorrectly to be \"stomach pumped\".) I have only \"pumped a stomach\" one time in these last 12 years. Massive + verified TCA overdose within 1h prior to arrival. That's the ONLY case.",
"Point of interest: in my culture in South Africa we steam cook blood from a slaughtered cow(around 2.5 liters maybe more) and eat it, similar to blood pudding without the cereal and fat or suet. I don't think swallowing large amounts of one's own blood would be dangerous but ey! I'm not a doctor.",
"Had an open wound in my throat after a mostly successful tonsillectomy. About 12 hours of bleeding into my stomach resulted in nausea, lots of vomiting and a unique texture to the vomit that many women (am cishet male) have likened to the tacky, partially clotted results of menstruation. Can honestly say that the whole fear of aspirating vomit is a whole lot more real when you’ve got a fairly long string of congealed blood going deep into your stomach that needs to be slowly pulled out for fear of choking. That was 10 years ago and I haven’t been able to eat anything remotely organ-y since.",
"Because your stomach isn’t good at processing/digesting it. I used to suffer REALLY frequent and long nosebleeds as a kid. i was always told to tilt my head back too. One time when my nose was really playing up for a few days, I had had my head tilted back for so long whilst I was bleeding that apparently a LOT of blood had entered my stomach. That was the one and only time I have ever projectile vomited. This large volume of mixed blood and stomach acid came flying out of my mouth at least a couple feet. Like a friggin laser beam. All I could taste was acidic iron. I felt great after though, as my stomach was completely fucked leading up to that moment. The feeling of so much liquid rushing out of my stomach so quickly was not nice though. I sometimes still get nosebleeds, but I always remember to tilt forwards instead of backwards now, hahaha. Actually helps the bleeding to stop sooner too."
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njwu8a | What exactly is 'Soil' or 'Rock' made of? | I understand that it's made up of minerals but what is in the minerals? I just can't put my finger on it, what is that igneous stuff made of, and are the metamorphic rocks made of the same thing?? | Earth Science | explainlikeimfive | {
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"[Here's an article]( URL_0 ) that details the chemical formula of several of these minerals. Basically, you're looking at silicon oxides with various metals or other chemicals attached. Soil is generally sand (tiny \"rocks\") with a lot of organic material (small pieces of plant, animal poop, etc.) thrown in.",
"Igneous rocks are made of lava that has cooled down. A lot of it is composed of the mineral quartz (Silicon oxide, SiO2). These rocks eventually break down because of weathering. The individual particles of the broken rock get swept downstream by water and deposited somewhere. Over time these deposits get compressed by the weight of more accumulating deposits above them and turn into a sedimentary rock, e.g. sandstone, a large part of which is also quartz, not coincidentally. As this sedimentary rock gets buried or pushed extremely deep, it turns into a metamorphic rock, e.g. quartzite (guess what it’s made of). After this rock eventually melts into lava, it can get spewed out through volcanic action again to become igneous rock and start the cycle anew. Another common mineral is feldspar, which is an aluminosilicate, made of aluminum, silicon and oxygen. Another common stuff is calcium carbonate, which is what mollusk shells are made of, and again not coincidentally dying shells is how it gets deposited in the first place."
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njxvg9 | Why do image and video quality worsen the more they are saved and uploaded? What contributes to this? | Technology | explainlikeimfive | {
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"Many of the common file formats use various forms of 'lossy' compression, which means that they reduce the file size by discarding some of the information contained in the image/video. So each time you save the file again it gets compressed again, and more data is lost. The algorithms that they use are designed to keep the data that's most important to the image quality, but they're not perfect, so over multiple save/compression cycles, more and more of the original image is lost and the amount of weird compression artifacts grows. There are 'lossless' compression file types/algorithms, but they generally don't reduce file sizes nearly as much.",
"Every time you put content into editing software and make any changes, the saved file will be re-compressed and that will reduce the quality. RAW photo files, RAW format video, and so on do not suffer degrading if that is your saved format. The problem is that the file sizes for those are huge, so no one shares RAW format."
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njyctw | Why do some sounds like fingernails scratching a board makes us feel so uncomfortable? | Other | explainlikeimfive | {
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"Fingernails scratching a chalkboard produces sound in the range of roughly 2,000 to 4,000 Hertz, which is the range human ears are most highly sensitive to. This also happens to be the range that a human scream and a baby crying fall into, and both of those sounds are closely linked to survival - member of the group is injured or terrified and our near-helpless young needs our attention - so a strong, fast response to those sounds is evolutionarily beneficial."
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njyfxl | why is the curve of fastest descent not a straight line? | As in the [brachistochrone curve]( URL_0 ). Does it have something to do with gravity? I don't understand how it acts more strongly, especially considering the curve is a longer distance, yet a ball can travel faster on it. | Physics | explainlikeimfive | {
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"So the problem isnt about descent but about getting an object down and accross. With a straight line the ball only reaches its maximum speed at point b. You can speed this up by getting as much speed downwards before converting it to horizontal speed. By going down even further you gain additional speed to get accross which is then spent climbing back up to b. If it was just descent it would be a straight line.",
"Yes it has to do with gravity. Along with potential energy and Kinetic energy. When you stand on top of a hill, and gravity is pulling you down, you have potential energy. When you then lay down and start rolling down the hill, letting gravity pull you down, you’re converting that potential energy into kinetic energy, or movement energy. By having a steeper drop first in the brachistochrone curve, the ball’s potential energy is more rapidly converted into kinetic energy. Meaning you get more movement/more speed, quicker."
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njyl38 | Is it possible to be born with YY chromossomes? | Biology | explainlikeimfive | {
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"It would be 100-percent fatal. The X chromosome holds hundreds of important genes that the Y chromosome simply does not have. The Y chromosome has just a couple dozen genes, including the gene that switches embryo development to the male type (instead of the female type, which is kinda the default). So not having an X chromosome would likely cause the cells to not function at all.",
"A fetus with only one Y chromosome and no X chromosome is not viable and cannot survive. Two Y chromosomes would be the same.",
"There haven't been any recorded people found with a YY chromosome. Some people are born with XYY chromosomes, about 1 in 1000 apparently male births. They seem to have a higher rate of learning disabilities, though it's effect on behavior (particularly criminal behavior) has been vastly exaggerated in media and fiction. Also others were found with XXX or just an X chromosome with nothing else or XXY. So the general consensus seems to be that you need at least one X Chromosome to survive.",
"The \"Y\" Chromosome is essentially an X chromosome with a large chuck of the genes missing, and 1 extra gene called SRY that causes the body to develop as a male. There are also a handful of other genes which are involved in testes. If you are YY, you would be missing a huge number of genes that are needed for life. You can be XYY though. Or XXYY or XYYY. Or you can be XX with the SRY gene copied across to one of the X Chromosomes. Then you'll develop as a mostly normal male. The Y Chromosome is just a very stripped back X Chromosome with a switch that causes the male development pathway to activate. Originally life all had XX and sex was determined by temperature. Then SRY gene evolved which forces maleness. Since two males can't reproduce, there wasn't a risk of someone having two X with SRY genes on. Then, over many evolutionary years, the X-with-SRY lost most of it's genes and become a Y. But that doesn't really matter too much, since you were guaranteed to get an X with the full compliment from your mother.",
"There is a rare genetic disorder which causes people with XY chromosomes to be born female but these do not normally go through puberty properly and are sterile. It would take some quite rare circumstances for there to be an egg without an X chromosome and I do not think we have any records of this taking place in humans. Although it is technically possible through a series of rare events. But even if we get an impregnated egg without the X chromosome it is not going to develop. Every chromosome have important genes that is required for our development. The most famous gene on the X chromosome is required to develop fully functioning cones in your eyes to see the color red. The reason why red-green color blindness is more common in men then women is because women have two versions of this gene, one on each X chromosome. So the chance of both being defective is quite low. However without an X chromosome there would be no genes available for this. And it is not only color blindness but you would be missing almost 5% of your genes making it impossible for your body to produce a wide range of proteins that are required by your body. And that would obviously not work at all."
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njyu59 | Is economy finite? | By this I mean to ask that is 'the value' of money limited and works just like the 'conservation of energy'. If yes, then does that mean a country getting richer will increase the probability of another getting poor. And if yes, isn't that a vicious cycle, is there any solution to that? | Economics | explainlikeimfive | {
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"The value of the economy is more or less determined by goods availability, money is just a tool to get the goods flow. Effectiveness of production rises with technical progress (a single worker is able to produce more stuff for more people to use), so the total economy of the world goes up. Trade also contributes because countries can exchange things they both need, making production and distribution even more effective. So it's not conserved."
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njyv18 | Why is eating humans not healthy? | I'm serious, I wanna know | Other | explainlikeimfive | {
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"A human physiologist here. & #x200B; Aside from the taboo and health requirements bordering on murder (you don't want to eat anything that has died of disease or old age, any edible meat should generally come from a healthy, freshly slaughtered animal), there are many diseases that are only transmitted through eating human flesh. & #x200B; Most common are prion diseases, which you generally get from eating human brains (or meat apparently). You might have heard from Kuru ([ URL_1 ]( URL_0 )), an **invariably lethal** neurodegenerative disease that is transmitted through eating human flesh and brains. There are also dozens of others, but those are less-known since eating human flesh is so rare. Some you might get from an otherwise healthy-looking person with no symptoms, so eating human flesh/brains is always a huge risk. & #x200B; So in short, prion diseases. Lethal, horrible prion diseases. Many other diseases too, but prion diseases are most common. No way to know beforehand whether you die an agonizing death or not.",
"Tiny things (like germs) that eat one animal may have trouble eating a different kind of animal. If you eat a human, the tiny things that eat a human have a higher chance of being able to eat you, and thus make you sick. In a related notes, the most famous disease assocaited with humans eating humans is a prion disease. It's a misshapened human brain protein, that when it hits a normal human brain protein, turns it into the exact same misshapened brain protein. You can get that misshapened protein in your brain by eating it.",
"Who said it wasn't? Human flesh is high in vitamin D and vitamin B6, not to mention a great source of protein. People will talk about prion disease, but you can also get that from cows and sheep. So long as you don't chow down on the brains of someone with a neurodegenerative disease like kuru or CJD you'll be fine. As for bugs, most humans are vaccinated and don't carry parasites. So long as youre eating a freshly slaughtered healthy human and are cooking it thoroughly, I don't see why it would be anymore unhealthy than eating any other animal. Though you might spend the rest of your life in prison for doing so."
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njyy4c | Why does weight go only to my stomach and not my arms or chest :( | Biology | explainlikeimfive | {
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"text": [
"It boils down to genetics basically. There's a natural deviation in the type of bodies so that our species is more likely to survive if there's a catastrophic event/illness. So your genetics determine where you will gain weight first and where you lose. If you gain a lot of weight, you will eventually see it going to your arms and chest"
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njz4x1 | Why do the same temperatures feel different? | Other | explainlikeimfive | {
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"text": [
"More than likely it is due to humidity. The more humid it is the more you feel the temperature. It can be 120\\*f with no humidity and it would feel the same as 85\\*f at 100% humidity."
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njz9oy | How should I recognize what time signatures are used in songs? | I am not talking about basic time signatures like 4/4 or 3/4 instead I am talking about stuff like 11/8 or 5/4 etc. | Other | explainlikeimfive | {
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"Firstly time signatures can be ambiguous. A lot of songs can be written in different time signatures and still be played the same. So guessing a time signature that is different from what the sheet music say does not necessarily mean you are wrong. When identifying the bars you should be listening for the first downbeat of the bar which is often emphasized. So you would count 4/4 as **1**\\-2-3-4-**1**\\-2-3-4-**1**. And this is usually audible in the music. It does not always sound as obvious as in for example waltz but after some practice you should hear this in most songs. And when you listen for this and also for any rhythmic repetitions you should be able to identify a bar and then just count how many beats there is in that bar. So if you hear something like **1**\\-and-2-and-3-and-4-and-5-and-6-**1**\\-and-2- ... you are dealing with a song in 11/8."
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njzb4y | Why do we scream when we’re frightened? | Biology | explainlikeimfive | {
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"To warn our nearby kinsmen and tribe members of danger, so that they would come and rescue us, or else run away and avoid the danger themselves. Both of these outcomes are good for our genes: in the first case our genes are saved, in the second - the very many genes that we share with our relatives are saved. It’s an instinctive reaction hardwired into our brains by evolution many millions of years ago."
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nk0291 | How do you force a passenger plane down, they can't just shoot a civilian aircraft if the pilots refuse? | Other | explainlikeimfive | {
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"Oh, they certainly can shoot the plane down. When you fly over the sovereign territory of Country B, you have to do what the government says or the Air Force of B will be permitted to shoot you down. There are international agreements to regulate this, and some countries have violated the rules and been sanctioned for it.",
"Actually they can, wikipedia lists 39 cases URL_0",
"Who is \"they\" in this question? Because a lot of armed groups and countries have demonstrated that they will in fact shoot down civilian aircraft.",
"Specifically in this case, they called in a bomb threat. Which gives them justification to send up an \"escort\" fighter jet to ensure the \"safety\" of all the passengers on board and force the plane down. In other words, they lie in such a way that the airline can't afford to refuse.",
"They CAN shoot the plane down. Sure, it would suck for the hostages onboard but I'm sure in a post 9/11 world, it's preferable to losing even more lives. An airborne passenger plane is a potential missile.",
"they absolutely can and will shoot an airliner down if its deemed necessary, especially in the post 9/11 world, all sovereign nations have regulations regarding which aircraft can exist in their airspace and violating these rules will get you sanctions at 1st but if ignored you are given free reign to defend your air space as per military procedure, this is the time where you'll see interceptors being deployed for final warning/escort(close range radio comms) followed by a takedown if authorized and non compliant. skipping this procedure however can be seen as a act of war if proven to have been malicious. this is also why spy missions performed by aircraft are done with \"Stealth\"/unmanned crafts and at VERY high altitudes in order ot dodge Radar detection and as a loophole of \"airspace\".",
"That actually is what they would do. They'd attempt radio and signals first to order it down of course. Maybe even a burst across the bow. But end of the day if the order is to force the plane down the only way to do so is to shoot it down, and they would",
"They can and would if it seemed necessary. I think they'd prefer that to another 9/11. If the plane has really been hijacked by someone intending to use it in that way, the civilian passengers are going to die anyway, so it's a matter of preventing further death.",
"You start by having the control tower order them to land. They're supposed to follow instructions and land. If they do, you don't have a problem, so I'll assume they don't. You then send military fighter jets to intercept it. The pilots of those jets radio the airliner and order him to land. (There are standard frequencies for stuff like that, and airliners are supposed to listen to them.) If he doesn't, they can do various things to intimidate him, such as flying by at high speeds, flying close above him, dropping flares, or firing their guns in front of him. If he still doesn't land, they can try to shoot to disable his engines, but at that point they're likely to do enough damage to bring the plane down. And yes, they can shoot him down. It's very easy to shoot down a target that big and slow, and if he's in your airspace and not responding to instructions, you have every right to do so. If he's not in your airspace, that's a matter for the respective governments to deal with, and it might come down to whether either or both countries want to go to war over it. Usually, they'll land when the tower orders them to land, because few pilots are going to risk their career, not to mention their passengers and their lives, by refusing to follow the orders of the tower."
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nk0y62 | why intermittent fasting is good for you but skipping breakfast is not. | My doctor told me IF was great and it was how she lost weight but when I researched it (okay, 5 minutes on google) it just sounds like skipping breakfast which everyone tells you not to do. Am I missing something? | Biology | explainlikeimfive | {
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"The skipping breakfast is bad for you thing is a myth, mostly made up by cereal companies. That doesn't mean some individuals don't function better with breakfast, though. Diets are all about what sort of calorie management works for you. Different people will have success with different ones. I will say that I prefer IF because instead of trying to make it so you're magically never hungry, it's more like \"you're going to be hungry sometimes but that's ok, you don't need to eat every time your dumb animal body says you're hungry.\"",
"Breakfast is no more important than any other meal. It *helps* with energy in the morning, but it's not nearly as important as most people would have you believe. It's best to have enough food over all in a day (spread into a few meals) than to eat at very specific times, like just waking up.",
"When I am on a solid workout routine with lots of weight training, breakfast is a must. I usually wake up absolutely starving. When I'm not hard into it, I can skip breakfast and I don't naturally get hungry until about between 10-11 am. I don't like to force myself to not eat until a certain time, so I just listen to my body's cues and eat accordingly while tracking calories. bottom line, there's no one answer. Your needs may change over time. Don't force something that might not be working (eating breakfast, or skipping it) and do what works for you specifically.",
"Skipping breakfast when you would normally eat it means your body is missing a crucial energy source when it wakes up. It doesnt dip into fat stores because its expecting and begging for food and then you are hungry all morning until lunch. This stresses the body and doesnt feel good. In intermittent fasting, you train your body to clear the digestive system during the night and dip into fat stores in the morning. This gives you energy and is most of the weight people lose. The other part of the weight loss comes from the slight difference between the eating habits. Skipping breakfast is skipping one meal. Intermittent fasting is only eating in a few hour window every day. This cuts out extra hidden calories you may not think about along with the snacks at the worst time that really mess up your digestive rhythm and hormones. If you want to learn scientific specifics, do some research about insulin's role in the body.",
"Intermittent fasting is not about \"skipping\" a whole meal. The idea of intermittent fasting in it's most popular form is a schedule where you can eat 8 hours of a day and don't eat anything the other 16 hours. In contradiction to other diets it doesn't focus on *what* you eat but *when* you eat. So that means that in those 8 hours you can simply eat what you'd normally eat on a day. The main reason people lose weight because of it is because they stop eating something every hour during the whole day, and as a result reduce their overall calorie intake. Added benefits are that fasting allows your body to start op processes like autophagy which would normally not start because your digestive system is 'in use'. Which in return allows your body to burn a part of it's fat-store. Also: you can drink outside those 8 hours, but limit such to water, tea and black coffee (no sugar) & #x200B; Source: Been doing IF for over 2 years now, and: [ URL_0 ]( URL_0 )",
"Intermittent Fasting IF is a newer idea. That isn't to say it is bad, it is backed by actual facts and studies. While a lot of the classic wisdom is also based on some faulty ideas. There is valid points in nearly all of them, but the reason those ideas were so good for you have been lost a bit. To answer just your question: So it is important to eat quality food when you break your fast. Your body responds differently when just coming off of a fast compared to having eaten more recently. But you don't have to eat the classic \"breakfast\" in the morning. You can break your fast whenever. On the topic of when you eat. An earlier eating window is a bit better as eating right before you sleep can disturb your quality of sleep, as your body is half asleep and half digesting. But you can safely skip a morning breakfast and still put your eating window well before you go to sleep. I do want to leave another note promoting IF. The western diet is way off for multiple things but the abundance of food throughout the day has really messed up our eating habits and in particular a number of hormones that regulate weight. Keeping a consistent eating window of 6-8 hours (or less if you want, OMAD is a good option for weight loss) helps restore proper hormone balance. And once adapted you really don't get the same hunger cravings which allows you to easily choose higher quality food options when you do eat."
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nk44en | If pickles are made from cucumbers, then why have I never seen a cucumber sized pickle | Other | explainlikeimfive | {
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"smaller varieties of cucumbers with thinner skins are better for pickling than the large, thick skinned ones most commonly seen as raw cucumbers.",
"Because you haven't grown them. There are certain varieties of cucumbers that are better for salads or similar usages, and that's what you see in the grocery store. Other varieties are smaller, different color, and are used for pickling. This is the perfect time now to answer your question. Go to any place selling garden seeds and look. You'll find a bunch of cucumber varieties, with photos and descriptions.",
"Pickles are usually made from a specific type of cucumber, which are smaller than other types. These are called \"pickling cucumbers\"",
"Because most people don't want to buy a pickle that big. I have seen a pickle about ten inches long and three inches in diameter, but it was at a specialty deli.",
"Pickle jars are usually smaller than entire cucumbers, so smaller varieties of cucumbers are used for whole pickles. Lots of pickles are sliced cucumbers too, so it doesn't really matter what size they are."
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nk481j | What prevents us from seeing source code in closed source software? | Doesn't that code have to be somewhere in the app in some form for the app to function? & #x200B; EDIT: Thanks for all the responses. I think I get it now. | Technology | explainlikeimfive | {
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"No, the source code is more like a recipe which *creates* the app code which is needed for the program to function. The source code is all laid out in a logical, human-designed and human-readable format, and then a compiler turns that into a much tighter, optimized, machine-readable version of the algorithm which is described by the source code. This machine readable version is called, appropriately, machine code. There do exist programs called decompilers, which can go the other direction and give you source code from a piece of machine code. But a decompiler isn't just like \"Give me *the* source code this was compiled from.\" It's more like \"Give me *a* source code which, if compiled, would produce this machine code.\" What comes out is likely to be ugly, unreadable, and look like nonsense to a human, even if it compiles and runs just fine.",
"No. The source code is roughly analogous to a blueprint or a set of plans. After a program is written, it is then \"compiled\" which takes the source code and converts it into a lower level programming language that a computer can more easily and quickly understand. Your question would be somewhat similar to trying to take your house and translate it back into blueprints.",
"Source code is the recipe for making the cake. The actual program is the cake. Open Source software publishes the recipe. You can either bake it yourself, or sometimes you can find someone who will bake it for you. You can also tweak the recipe to fit your own taste. Close source software just serves the cake and keeps the recipe secret.",
"All code ultimately gets converted into \"machine code\" at some point before it is run. This is a stream of 1s and 0s representing basic actions that can be performed directly by the processor in your computer. By this stage, human-friendly names and comments have been removed, and many high-level commands will have been broken down into more basic ones. It is in principle possible to examine this code and work out what it is doing, but it can take a lot of time and effort. Depending on the software, this process may be carried out almost in its entirety prior to the software being distributed, or it might happen mostly as the software is run. So you might find that all you have on your hard disk are a bunch of files that look like random gibberish if you open them in a text editor, or you might find that most of them are human-readable code, or you might find a mixture. In addition to this, a lot of companies go to extra lengths to make it more difficult for people to reverse-engineer their code. This might include: * encrypting certain sections of code, and having the rest of the program decrypt them when they need to be run * obfuscating code, for example by removing whitespace and comments and changing names of things so that it's less clear what they mean, in order to make the code less human-readable even though the computer treats it exactly the same * requiring users to connect to your servers to perform certain tasks, so that some of the code can be kept on your servers and run there - this means that unauthorised people can't even look at it",
"The code that gets packaged with the application to be executed on your processor comes in the form of machine code. This is a format which is highly optimized and minimized so that the electronics in the processor can easily execute the instructions. This is very detailed minimal instructions of exactly where each byte of data should be copied to and from memory addresses and each register and exactly what calculation should be performed on each byte of data. However there is no mention of what exactly this means and how it fits together on a larger level. So while it is possible to convert this machine code into human readable assembly language it is very hard to interpret what this code is doing. It is not impossible though but it can be painstakingly slow to do so."
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nk4ajx | What’s the difference between dolphins and whales? | I read that killer whales aren’t whales, they’re dolphins. But I also read that dolphins are whales. I’m so confused. So what are these things? | Biology | explainlikeimfive | {
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"Well, the difference is at what level of the scientific classification you break them up. URL_0 They are all cetaceans, which is the infraorder of the scientific classification system for all of these animals. But you go one level down and and now whales and killer whales are in different families. Killer whales are a member of Delphinidae which is the dolphin family, whereas Grey Whales are a member of the Eschrichtiidae family which includes grey whales and other similar animals. If you go high enough up in the scientific classes, they are related to Humans as well."
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nk4iav | Why are people laughing more when they are in a group? | When I am watching a show or a comedy, alone and there's something funny most of the time I don't laugh, but when I watch something or see something with friends I laugh more. Why is that? | Other | explainlikeimfive | {
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"This is what scientist mean when they say we are a “social species” our brains are highly tuned to understand what people are feeling/saying through body language and vocalization. Working in a group means better survival odds, so if a group of people are having fun you’re brain desperately wants to be a part of the group and laughing is a no-brainer, low effort way to show you are amicable, not threatening, and want to cooperate with the group",
"URL_0 Fun Fact: Humans will instinctively look at the person they most desire approval from and safety with first when they laugh. Can confirm, this is a damn fine way to get an idea of who's got an eye for you in a friend group.",
"It’s not really known why but laughter being contagious is thought to be some sort of laugh detector in humans. Possibly a neural circuit in the brain that responds exclusively to laughter and generates a response of laughter, similar to contagious yawning. It’s brain chemistry. As to what purpose this served evolutionarily, maybe it’s a bonding thing that helped humans to relate to one another and come together as a social species."
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nk4or1 | Why aren’t meteorites the most valuable objects/minerals on the planet? | It seems like something that didn’t originate from our planet would be worth far more than gold or diamonds, which can be found almost anywhere in the world. The statistical odds of something floating through our massive universe and hitting our planet intact would seem to be worth far more considering how rare that is. Is it because it is mostly only iron and nickel… minerals we have plenty of? | Earth Science | explainlikeimfive | {
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"You nailed it. Most meteorites are composed of very common elements found abundantly on earth.",
"Meteorites are far more common then you might think. And they do not look that pretty so most people do not want to pay a lot of money to be able to show it off. Diamonds, gemstones and gold are much prettier. And the minerals in meteorites like iron and nickel is fairly common in the Earths crust so we have no need for it to build technological things like we do platinum.",
"You are correct in the sense that meteorites (that survive Earth entry) are largely composed of now-commonplace materials, like Iron. Space iron is still just iron, so as a material there is no special value. Some meteorites have value as meteorite, like, I might pay a premium to have a meterorite-mineral necklace. It's worth noting though that this wasn't always the case. King Tut was found buried with an iron knife which would have been an item of unimaginable value in his time as the Egyptians didn't have any methods for mining iron; the knife was made of a meteorite iron so it clearly was a very, very, very special item in his time.",
"Meteorites are rare, but they are mostly just ugly pieces of nickel/iron, so for much of human history they were ignored. Diamonds were also considered relatively worthless outside of decorative novelties for royalty, and more recently for industrial applications. It wasn’t until the DeBeers cartel started pushing the love is for ever, get her a diamond campaign. Now days collectors of rocks and minerals will pay a higher value for meteorites simply because of the novelty value of having a piece of “space rock” in their collection."
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nk4x5z | why can’t we remember things until we’re 4-5 years of age? Why can’t we remember things before that age? | Biology | explainlikeimfive | {
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"> *\"To explain why this happens, though, the researchers led by Paul Frankland, a senior scientist at the Hospital for Sick Children in Toronto, hypothesized that the memories themselves actually ended up in the long-term “memory storage room” — it’s just that the hippocampus lost track of where these were put. Imagine a tiny room that rapidly grows into a whole warehouse, but you only have a limited amount of resources to keep track of and successfully store and tag goods for later retrieval — you’ll get a lot of boxes tucked away with no idea what’s inside them, and most likely you’ll leave them like that. This is what happens to the hippocampus as it matures and huge numbers of new neurons come online and need to be hooked into existing circuits. As growth slows down, the brain is better at keeping pace and can do a better job of tracking where memories get stored, which is why long-term memories become better as youngsters get older.\"* Copy-pasted, but pretty ELI5 IMO. Source: URL_0",
"This is called infantile amnesia and no one knows for sure why it occurs, though it's probably a combination of different factors. The most convincing reason for it, in my opinion as someone with a bachelor's in psych, is that the area of your brain that stores memories isn't fully developed until 2-4 years old. Through evolution, humans have \"prioritized\" the development of other parts of the brain from 0 to 2ish."
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nk4xnp | What exactly is depression, in a neurological/chemical sense? | Biology | explainlikeimfive | {
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"We don't know at this point. The common explanation for depression is that it is caused by a deficit of certain neurotransmitters in the brain. Typically the blame is placed on not enough serotonin. This is called the monoamine hypothesis. But the monoamine hypothesis is not good enough to explain depression on its own, because if you artificially deplete serotonin in the brains of people who are not depressed, they do not become depressed.¹ Similarly, while medicines that raise serotonin levels in the brain do so within hours after administration, it takes weeks for a typical patient to respond to the medication.² In combination, these observations indicate that it's not simply a matter of low serotonin in the brain. There are other pieces of evidence that the monoamine hypothesis is not accurate. Increasing serotonin doesn't resolve depression in all patients. A substantial fraction (25 - 40%) of depressed patients don't respond to monoamine therapy. There are effective antidepressant medications which don't do anything at all to the levels of serotonin or norepinephrine or other monoamines in the brain (one that has gotten a lot of press and has recently been approved by the FDA is ketamine). The actual cause of depression is still an area of active research. There is strong evidence that there are a number of heritable traits which predispose people to depression, at least some of which play a role in disrupting the monoamine production and use in the brain. It is likely that the cluster of symptoms which we call depression is caused by a combination of circumstances and multiple, perhaps dozens, of genetic traits working alone or in combination. 1 . 2 URL_0"
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nk5aa9 | Why is a 'sight for sore eyes' pretty but an 'eyesore' ugly? | Other | explainlikeimfive | {
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"Well, when you have been looking at things that makes your eyes sore, it's soothing to find something that isn't an eyesore. Basically one is so ugly it hurts the eyes, and the other is \"something nice among ugly things\"",
"An 'eyesore' is cause of discomfort to the eyes. A 'sight for sore eyes' is a thing discomfortable eyes crave."
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nk5yjp | How can people tell if the tide is coming in or going out just by looking? | Earth Science | explainlikeimfive | {
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"If you spend enough time around the ocean you can tell the difference. The behavior of the water changes on whether the tide is rising or falling; if the tide is going out there will appear to be more force going out when a wave approaches, rip currents will be stronger, things like that. Once you're used to it the texture of the water is a dead giveaway. Plus other factors like high water marks Source: I surf a lot",
"Look at the shore, if it's wet above the waterline, then the tide going out. If it's dry above the waterline it's coming in. (Waves my make this harder to see). Look at the sea grass, which way is the water bending it. If there is a narrow point, then you can obviously see the movement of the water: URL_0 Put a stick in the sand at the beach where the tide currently is, wait 20 minutes, look where the water is now."
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nk6b5h | Why are degrees measured in the way they are, ie: 90 is a right angle and 360 is a revolution, as opposed to a more simple/rounded number like 500 or 1000? Is there a reason behind it or is it arbitrary? | Mathematics | explainlikeimfive | {
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"It comes from the ancient Babylonian number system. Their number system was based on the number 60 which is a very practical number if you want to split things evenly. They divided the circle into 6 equal sections and then these sections were further divided into 60 degrees. We further divide degrees into 60 arcminutes and each arcminute into 60 arcseconds. We just have not found a good advantage to changing this. Although there have been attempts. The most famous was the attempt at introducing grads. There are 400 grads in a circle. Mathematicians however prefer to use radiens. There are 2 pi radiens in a circle which makes a lot of mathematical equations much simpler then when working with degrees.",
"It is arbitrary in the sense that it *could* be anything. However, 360 is a very good choice because it is evenly divisible by many numbers: 1, 2, 3, 4, 5, 6, 8, 9, 10, 12, 15, 18, 20, 24, 30, 36, 40, 45, 60, 72, 90, 120, 180 and 360. That's twice as many as 500, to use your example, so is arguably more of a \"round number.\" 500 isn't even divisible by 3. As for *why*, it's because we have been doing it that way since before history. We don't even know who decided it. It's at least as old as the ancient Babylonians.",
"It’s a couple of things. Mainly the Babylonians used a base 60 number system. So where we use base 10, and have 10 different symbols for our numbers, they had 60. The Egyptians then took their number system, realized they could put 6 perfect triangles together in a hexagon (where each corner is 60° thanks to their number system), and fit a circle inside. With 6 corners of the triangles together, each of which was 60°, you had 360° in that circle. It also could have to do with the days in a year. Early calendars had 360 days, so each day was equal to 1° of movement. 360 is also a cool number because you can divide it neatly by lots of other numbers. There’s no number smaller than it with as many factors. So it makes it a little easier to do math on circles with 360°, and that’s helped keep it the standard over literally thousands of years.",
"It's mostly arbitrary, and there are other systems like gradians 400 in a revolution ( URL_1 ) and radians 2 * pi in a revolution ( URL_0 ) 360 degrees however are nice however because lots of numbers divide in evenly without fractions. There are 24 numbers that evenly divide into 360, but only 12 into 500, 15 into 1000.",
"The reason that 360 was chosen is not known today. The usage of 360 degrees starts in ancient Mesopotamia. There is records if it is used in Babylonian astronomical text at least as early as 2000 BC. There are a few hypotheses. One is that that a year is 365 day. 360 is very close and divisible by more numbers like the on average 12 lunar months you have per year. So the sun moves relative to the start close to 1 degree per day. Another is that the Babylonians used a number system with base 60 so having 360 degrees is 6*60. The Babylonians divided a degree in 60 minutes and a minute in 60 seconds. They did not call it that, the current name is from Latin The usage of minutes and second for time stats with Robert Bacon in 1267 for astronomical calculates and are introduced in the clock in 1675 when they were exact enough. So the minutes and second for time is milenias later than for angles. So there the original reason is not known but we can speculate. The reason we use it today is that that the usage in astronomy spread and has continued to this day. To know why you need a time machine. There is one other common angular measurement and that is Radians where you have 2Pi radiance for a complete revolution. The explanation is if you have a circle with radius 1 and measure angles into the light of the arch of what you measure will be the same as the angle in radians. The circumference of a circle with a radius of 1 is 2Pi. To have the angle as the arch length makes a lot of calculation a lot simpler. So if there is a natural measurement for the angle it is in radians."
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nk8o92 | Why are larger animals less likely to develop cancers? | Biology | explainlikeimfive | {
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"I think most are equally as likely to develop cancer, but their size means that the cancer takes much longer to cause serious damage as all cancers grow at a similar rate regardless of the size of their host. Some very large animals such as whales have another mechanism which defends them, known as supercancers. This is essentially when the cancer develops its own cancer (or a different cancer) which competes with the initial tumor for space and resources. This will either result in the death of the initial cancer, or will slow the growth of both cancers, effectively delaying the death of the animal.",
"I saw this video before, and I think it does a good job of explaining what they know about it [ URL_0 ]( URL_0 )",
"Check out this recent post from askscience, it is pretty detailed on a simple way URL_0"
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nk990a | What is a logarithmic scale? Why is it more useful for some things than a regular numerical scale? | Mathematics | explainlikeimfive | {
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"Your standard scale will have evenly spaced lines at 1, 2, 3, 4, 5, 6, 7.... A log scale will have evenly spaced lines at 1, 10, 100, 1000, 10,000 Log scales are useful for looking at things that tend to grow exponentially [like say deaths in a pandemic]( URL_0 ), they let you get details at both the lower end and the higher end. If you look at the left plot on there, you really can't get any details before it starts ramping up around March 22, everything left of that basically looks like its 0 because fitting both 10 and 40k on a graph with a linear scale really squishes data at the low end. If you look at the right plot which is a semi-log (x axis is linear dates, y axis is a log scale) you can see that things start getting reported around March 4th and then proceeds to climb at roughly a straight line. If you plot something like 5^x on a semi-log plot like this you'll get a straight line so when we look at exponential growth we expect to see a straight line. Log plots are used whenever the difference between the smallest and largest number is several orders of magnitude. If you are plotting sound over time you'd work in dB which are a log scale because the difference between the loudest sound and the quietest sound you can hear is 10,000,000,000x difference in pressure",
"Imagine you wanted to plot the net worth of people in your area in a graph that shows all the data. Now most of the net worth will be around the lower end with some higher in between. So you can nicely see how the worth is distributed among the people. Then suddenly Elon Musk decides to join your area. Now your nice graph is screwed. Why is it screwed? Because the number line that previously was at let's say 500k max suddenly jumped to 147 billion. So the graph, as it is supposed to show all points, now is squished such that Elon Musk is at the top, a single outlier in the whole distribution. Even the richest guy in your area before is a measly 0.00034% on the scale. (Yes that's right, those are 3 zeros after the decimal AND it's percent. That is how laughable 500k are in that distribution) This makes it impossible to see any difference between the 500k guy and the 300k guy the 30k guy and so on. They're all down in the same line from Elons perspective. So now you take a logarithmic scale, meaning you take their net worth, throw it into a logarithmic function and then plot that value. You obviously have to adjust the y axis accordingly. The 30k guy is now a 4.47. The 200k guy is now a 5.3. The 500k guy is now a 5.7. And Elon? Well he's an 11.17. These now fit on a single graph and you can still make out differences between the \"smaller\" numbers. Logarithmic scales are generally often used when exponential growth is concerned, like population growth, spreading of diseases. Also when you have to work with data that spans a huge range of values, like comparing the size of objects in the universe. Using logarithmic scales and transformations is very common in machine learning and data science.",
"OP, take some time to really digest this concept. Logarithmic plots are used frequently because they're great ways to condense data into more digestible formats but it's important as a consumer of data (news media, maybe at work, politics, etc) it's important to understand what you're being presented with. As a general rule, check the units, and the scale on any plot you're being presented with because people can do all sorts of massaging to still show \"accurate\" data but in ways that wildly miscommunicate what the data actually presents. My college statistics courses really changed the way I saw the world. It made me a skeptic of any data being presented to me, and I now I ask more questions. That's a healthy skepticism to have because sometimes you'll find that after you start to digest the plots, you can make some pretty accurate assumptions about the author's opinions or beliefs just in how they presented their data, which I'd argue is an objectively bad thing. I'm ranting on something off topic here, but the main point I was trying to make is that log plots are very useful tools but understand them well so you can be sure you're not reaching the wrong conclusions just because the data being presented looks a particular way, even if that data is factual, it can be presented in a way that's misleading."
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nk9jzg | what does it mean when a country has sanctions placed upon them? | Other | explainlikeimfive | {
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"Restrictions on financial transactions or trade. Countries agree not to allow trade to go to a particular country. Feel free to correct me if I have something wrong."
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nk9uzm | Why is it worse to landfill food waste compared to composting? | I’ve seen it has something to do with lack of oxygen, but how can this make so much difference to what a rotting food produces? | Earth Science | explainlikeimfive | {
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"Bacteria need oxygen to break down living matter. In a landfill, the living matter is usually sealed in multiple layers of plastic and then buried underneath other material with no oxygen, so there’s none for the bacteria to use. In compost, the material is mostly organic and aerated regularly to facilitate healthy bacterial growth. The result is rich nitrogen-fixed loam. “Rotting” is just bacteria in action: in a landfill, all rotting halts. The food is preserved as-is until it is again exposed to an oxygen source."
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nkb7gm | Why is Australia so hot when it is so far from the equator? | Earth Science | explainlikeimfive | {
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"It's not far from the equator. It's closer to the equator than Egypt for instance, and on par with much of the Sahara desert. Much of the north is in the tropics, with the south in the subtropics Perhaps the maps you are familiar with are the ones that don't bother showing how much Antarctica there is, and cut it off. That would make Australia feel more southern than it truly is.",
"Its actually not far at all from the equator, especially the northern end. Even Tasmania is closer to the equator than England.",
"It's not that far from the equator. It spans similar latitude from about Panama to San Francisco. A lot of that is desert and pretty hot in the US. Or go over to Africa, it covers pretty much the same latitude of the Sahara Desert."
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nkbess | why the earth's magnetic fields reverses? | The earth's magnetic field is known to shift occasionally. North and south reverse. But why does that happen? The earth's magnetic field is due to the direction of the rotation of the molten core. So does this core randomly start moving in the other direction? What causes that? And if it's reversing directions, shouldn't it stop at any point ? If so, why does it start moving in the other direction? | Earth Science | explainlikeimfive | {
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"URL_0 They're not sure yet. But models of the movement of Earth's liquid iron core have also resulted in seemingly random reverses, so it's something inherent to how the liquid iron is behaving."
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nkc6k7 | how long of a shower would you need to use as much water as a bath? | Mathematics | explainlikeimfive | {
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"If you have a combination tub/shower, just leave the plug in while you shower. Note the water level when you’re done",
"Or, put in the plug and take a shower until it's full. That's how long the shower can be. 😁",
"That would depend significantly on the type of showerhead you are using. You would need to measure the flow rate of the shower head, and then measure the amount of water in a full tub. Then you could calculate how long you would need to run the shower before the same amount of water has come out.",
"If you just want an approximation, looks like the average bath is about 110 liters, the average showerhead uses about 9 liters per minute. So, that would mean it would take about 12 minutes. To be honest, that's a lot shorter time than I would have expected, but can vary HUGELY depending on your bath size, if you have a high or low flow showerhead, how full you fill your bath..."
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nkcad1 | What do the letters in car models mean? | Technology | explainlikeimfive | {
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"It's mostly marketing lingo, and the letters can mean something different based on which car company you are talking about. Partly because those letters are trademarked. For Mazda RX is 'Rotary eXperimental' For Lexus RX it's 'Radiant Crossover' GTO - Gran Turismo Omologato - Italian for 'Approved for Racing' SS - Super Sport Honda CRV - Compact Recreation Vehicle"
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nkccxc | How did the Planck satellite take an image of the universe from 380,000 years ago? | Physics | explainlikeimfive | {
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"It didn't take a picture of the universe from 380,000 years ago. It took an image of the universe as it was 13.8 billion years ago which was 380,000 years after the Big Bang. It was able to do this because that's how long it took the light to travel across the universe. Just like if you take a picture of the Moon you're taking a picture of how it looked about 1.3 seconds ago.",
"It did not take an image of the universe from 380,000 years ago, but an image of the universe when it was 380,000 years old. At that time, the whole universe was so hot, matter itself was in a different, plasma-like phase. Think of how water becomes vapor at 100c or solidifies to ice at 0c. That matter didn't allow light to travel very far, just like the oceans don't allow it to penetrate deep. But since it was being generated by the heat everywhere around, it created a sort of a haze, a fog that created and absorbed light constantly. Then, around that 380,000 year mark, it grew cold enough for matter to form atoms, and suddenly the universe became opaque. All the light created in that fog suddenly wasn't being absorbed as much and could travel freely, even to this day. This light, the proverbial fingerprint of the universe, is called the microwave background radiation. And because it happened everywhere in the universe at roughly the same time, it is basically everywhere in space, but almost 14 billion years ago in time.",
"The photograph you mentioned in another comment is from a key point in the development of the early Universe: it's the moment\\* when the Universe cooled down enough to become transparent to light; prior to that the entire Universe would've been opaque. Light from that moment is still zipping around, getting stretched out into longer and longer wavelengths as the Universe around it stretches and expands. So in order to get a picture of it, we look for light at sufficiently long wavelengths to be that old. The picture (which is actually a whole bunch of pictures stitched together) essentially shows a \"bubble\" around us where the light emitted 380,000 years after the Big Bang is just now reaching us. Light emitted at the same time but closer to us would have already past us by. It is, of course, more complicated than that. There's a whole bunch of light in the Universe at many different wavelengths. So it took some guesswork and some math and a whole lot of computer processing to render that image. \\----- \\* Note that this is \"moment\" on the cosmic timescale. It's not actually a snapshot of one precise moment in time, just of a relatively narrow slice of the nearly 14 billion years the Universe has been around."
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nkct30 | How the US classes work in school, coming from someone in Europe | Other | explainlikeimfive | {
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"High school: 12th grade (senior year) - ages 17-18, this is the last year of high school and once complete, you can pursue a university degree 11th grade (junior year) - ages 16-17 10th grade (sophomore year) - ages 15-16 9th grade (freshman year) - ages 14-15, this is where high school begins Middle school: 8th grade - ages 13-14 7th grade - ages 12-13 Elementary school: 6th grade - ages 11-12 5th grade - ages 10-11 4th grade - ages 9-10 3rd grade - ages 8-9 2nd grade - ages 7-8 1st grade - ages 6-7 Preschool: Kindergarten - ages 5-6 Pre-K - (as in pre-kindergarten), this one's more or less optional, usually age 3-5 but it varies and there can be more than one year of pre-K Some schools do the middle school cutoffs differently, so I'm just speaking based on my experience."
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nkdogs | why do people pass out when they get punched in the face? | Obviously you can get "knocked out" but why does your body just go to sleep when you get hit in the face? | Biology | explainlikeimfive | {
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"They're brain rattles around in their skulls causing swelling and bruising. So you fall unconscious due to trauma.",
"if the punch is hard enough it will cause your brain to rattle inside your skull and when your brain hits the walls of the skull it can injure itself(bruising and swelling) this will immediately knock you unconscious and it causes actual damage, congrats you just had a concussion and should probably avoid further punches in the head in the near future."
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nkepdc | Why does our heart not get tired? | Biology | explainlikeimfive | {
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"Cos it's awesome. The heart is made of a special kind of muscle cell called cardiomyocytes. These cells contain a lot of mitochondria (the powerhouse of the cell) meaning they can produce energy faster than other muscles can. They're also given a priority supply of oxygen, so they suffer from you being short on breath slower than other muscles. Theoretically, other muscles could have these qualities too, but they don't need them, and having them costs more energy, so evolution didn't favour it - evolution hates to waste energy.",
"1) Cardiomyocytes are special muscle cells your body uses to create your heart. They have far more mitochondria than normal cells to keep up with the amount of ATP needed to keep the heart pumping. 2) The heart is basically the first in line for oxygen right after it hits the lungs. This means that there's always oxygen available and, absent something terrible happening like a blockage, the mitochondria will always be working aerobically with oxygen. Because of this they don't get fatigued like a normal muscle.",
"1: the heart is not a the same kind of muscle we have in our limbs they are meant for slow and methodical contractions which make them very efficient to run even under stress. 2: the Heart is not under your direct control, so you dont feel any form of fatigue from it unless something is very wrong or you strained yourself well above your safe limits(fight or flight.). cant even imagine a more hellish existence than one where we would need to actively manage our Heart Muscle :S."
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nkfzu9 | how do microphones in a phone not pick up any audio that the speakers put out? if I put a call on speaker mode, how do people on the other end not hear themselves? | Technology | explainlikeimfive | {
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"They do, and it is very difficult to mitigate. The first step is to isolate the speaker and the microphone from the chassis, as sound is a vibration and the chassis will transmit it better than air. Ths is mechanical engineers job, and it is not easy, esp. on a cramped cell phone. The next step is to use specific microphones that are directional, and will only pickup sound from a very near source. Then there is active noise cancellation, where a secondary (or more) microphone records the ambient noise to \"substract\"it from the one coming from the primary microphone. This is done by software. Finally, there are various filters, both software and hardware, to eliminate unwanted noise, like echo and larsen. some are integrated in chips, others need to be coded. People often use both. TL;DR: the microphone picks this up, but phones are made to remove it.",
"One very important point - conferencing software never feeds the sound from your microphone back to your speakers. They feed that sound to everyone else, but never to you. This means you can't get the short-loop feedback howl that is really easy to get in a PA. But you can get the long-loop warble from a loop that goes into your mic, out of someone else's speakers, into their mic, back to your speakers, and to your mic. Another thing they do is detect when you are speaking, and adjust the speaker volume down and the mic volume up, then restore the speaker volume and cut the mic once you stop. It doesn't make for a good result, but it works. You can also use a 'comb filter'. Carve regular notches our of the speaker sound, so that a graph of the frequency response looks like a comb. Then filter the frequencies that remain in the speaker output, from the microphone, with a 'complementary' filter. The sound you get from such a setup is - well, ugly - but at least you can get rid of the worst echo.",
"I hear myself all the time when my friends with Iphones talk to me on speaker it's fucking annoying because there's at least half a second delay and suddenly i'm talking to myself",
"The mics do record it. But then it depends on the software, as some do cancel it or ignore it. Where the hardware is placed also affects. Have a voice call in a game while playing both without headset, just speakers, and you will probably hear that feedback with a second of delay or so.",
"Electronic engineer here Sound's system in phones has something called \"negative feedback loop\" which basically means that it subtracts the output sound from the inputs sound. here is what it does in a function form (person voice + phone voice) - **(phone voice from feedback loop)** = person voice the bold **phone voice** is the signal fed through by the negative feedback loop.",
"Have you never heard yourself while on the phone? It happens (used to happen more often) and it's really annoying.",
"As someone who works in a call center, a lot of speakers do pick up their own audio on speakerphone, and the person DOES hear themselves. And we hate it.",
"Um we do? Every time all I hear is the echo of my annoying voice",
"Part of my job is taking calls from the public. I can hear everything going on in the background and I wish people didn't think phones were a magic device that only picked up speach. I can hear you eating, peeing, breathing. I can hear Wheel of Fortune in the background. I can hear the baby screaming on your lap. If you put me on speaker phone I do hear an echo of everything I say. If you call someone be courteous and do it from a quiet place.",
"I mean, I can definitely hear when someone has me on speaker. And I can definitely hear myself talking.",
"Just throwing this out there, as someone who works in a call center taking for 8 hours to people in their cellphones, your speakerphone doesn't filter out sounds as much as you think. Please, just take the call off speaker. I'm so tired of hearing myself echo back.",
"Basically, there are two microphones on most phones one of which is used for noise cancellation. They compare both audio signals from the speaker output as well as from the microphone and subtract those signals. Hence leaving the required signal to be transmitted.",
"The first thing a microphone will be connected to is a filter and then an amplifier. The filter is mostly to get rid of things outside of hearing range. Next it goes to the amplifier. The amplifier will have a built in common-mode rejection. This means that a signal on the input that is matching another signal will get snubbed out, while signals unique to the input will be amplified. Typically the common-mode rejection ratio is around 100 dB, so the sound of the speaker on your phone ends up being about 1/1000 as loud as your voice."
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nkgpnb | how come we have so many fossils of specific animals? | I've heard that 99% of animals won't fossilize and the ones that do are rare to even find, if that's the case then how come we have so many examples of specific species even across the world from eachother when surely the fossil record should just be a jumbled mess of at least only quasi related species, is it that some species are lumped together due to similarities or what? | Biology | explainlikeimfive | {
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"So there's about 4,000 mostly..ish full skeletons of dinosaurs out there. Dinos were on earth for 165 *million* years. So that's about one full fossil every 40,000 years that dinos existed. Modern humans have existed for about 200,000 years. So that would be like finding 5 human fossils. Total ove the entire time humans have been around. Yeah, we have found a lot of fossils. But there were 100s of billions of not trillions of dinosaurs out there. It *is* a jumbled mess. We have identified some 700 species of dinosaurs. There we're likely millions of them.",
"Because we don't. Almost all fossils you see in museums are replicas made from casts of fossils. The actual fossils are so rare and valuable that they're kept locked away. For instance, only about 30 T-Rex fossils have ever been found and they were around for about 2 million years. One estimate is that about 2.5 billion T-Rexes ever lived. So we've found 1 T-Rex fossil for about every 80,000,000 T-Rexes who ever lived. edit: Funnily enough scientists are glad it's this way. It makes it easier for science to study different species if we only have a few examples of each. It fits them in species boxes a lot easier. Edit 2: For something a bit closer to us we have about 300 Neanderthal fossils. Still not a lot.",
"The fossil record is a mess. But the number of fossils we have of a particular animal depend on how abundant that animal was and whether its habit was near clay soil, tar, or water/ocean. An animal that dies and quickly gets covered in clay will have a better probability of fossilizing. Ocean critters like sea shells are also abundant. Getting buried and fossilized in the ocean is easy. Some animals we only have one of their species on record."
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nkgtx2 | When you rub lotion into your skin and it vanishes, where does it end up? | Chemistry | explainlikeimfive | {
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"Lotions, creams, and ointments are all mixes of watery ingredients (water, alcohols, stuff like that) and oily ingredients. Creams are more oily than lotions, ointments are more oily than creams. Generally, the oils are either absorbed and/or stay on your skin as a barrier, and the aqueous components are either absorbed or evaporate. Things that \"moisturize\" basically add some water to the dried surface skin, then make an oily barrier on the surface to prevent evaporative drying again- water goes in, oils stay on top.",
"Your skin is a barrier to the stuff underneath like glands and tissues. The lotion (or the moisture in it) gets absorbed into the glands underneath. Sort of like a sponge?"
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nkgupa | what allows a hummingbird to hover and fly the way it does? Is there any type of bird capable of doing the same type of flight? | Biology | explainlikeimfive | {
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"It's wings can rotate on their socket more freely than other birds, who just flap mostly up and down. Also, they flap their wings much faster and are much smaller than most birds, allowing them to achieve lift without forward momentum. The cost of this is a huge need for energy, thus they have to constantly eat to survive.",
"Their wings moves in shape “horizontal 8”…so in same time, they fly forward and backward - stay in same spot. They flap 80 times in second! …pretty fast…but they burn so much energy, so they constantly eat fruit-sugar for instant-energy."
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nkhgqu | Why does pouring milk on ice cream cause ice crystals to form throughout? | Chemistry | explainlikeimfive | {
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"Because the water and fats in the milk, have different freezing points. Wich means that only the water freezes to form crystals and the fat part of the milk keeps flowing.",
"Milk is mostly 3 things: 1)milk fat 2)milk protein 3) water. The fat and protein is what gives milk it's taste and nutrition, but the water content makes up most of the milk by weight. So when you pour milk over ice cream it's basically like pouring water over ice. You will get tiny crystals of ice that form. The difference is that the tiny crystals are a different texture than the ice cream. So you notice them. When they form on an ice cube they don't really look for feel any different."
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nki4tw | Why is it recommended to place fruit in a brown paper bag to ripen? | I have often been advised to put fruit, such as avocados, in a brown paper bag so they will turn ripe quickly. This would be as opposed to leaving it on a kitchen counter. How does the fruit's containment inside of a bag increase the speed of the chemical process of ripening? Does it specifically have to be a brown paper bag or will others, such as a plastic gallon zip lock, have the same effect? | Biology | explainlikeimfive | {
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"Ripening avocados produce a gas (ethylene), which plays a part in the ripening process. Putting the fruits in a paper bag helps keep more of the gas close to the fruit, so it speeds up the ripening. Simple as that. The same is true of many fruits (apples and bananas, for example). Other sorts of containers might work too, but I suspect that you'll hit other problems if the container is too airtight. A paper bag is going allow at least some flow of gases. Other chemicals can be used to get the same result. Acetylene is commonly used commercially, for example."
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nki85g | Why are nut allergies and gluten intolerance so prevalent and serious in certain populations (like in much of the US), and negligible to the point of being even considered a myth in other parts of the world? | Biology | explainlikeimfive | {
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"It’s most likely that the rate of reactions in the population hasn’t increased but the social awareness, rate of diagnosis, and restricted diets limiting exposure has seemed to increase the number and severity. For most of human history something like a food allergy wouldn’t even have been a consideration because of the lack of food in general and a severe reaction may not have been correlated to the food when everyone else is fine. Over time we’ve become knowledgeable and sensitive to correlation...almost to a flaw. So now, instead of allowing children to have mild reactions and carefully exposing them to new foods over and over we have an indefinite all or nothing mentality about their diet at the smallest reaction.",
"Lack of exposure. For instance, for decades parents in mostly English speaking countries were told to not give their children nuts because they'll choke to death and die. Studies since have shown that children of parents who ignored that \"advice\" rarely have nut allergies whereas the children of parents who followed it have a much greater incidence of nut allergies. As for gluten . most of that is a fad. People read mummy blogs on the internet and follow whatever dumb advice they give.",
"So, can we start by examining the assumption that “nut allergies and gluten intolerance so prevalent and serious in certain populations (like in much of the US)”? What are the actual statistics on this? A quick search surfaced this from a 2013 study: > More than half of the countries surveyed (52/89) did not have any data on food allergy prevalence. Only 10% (9/89) of countries had accurate food allergy prevalence data, based on oral food challenges (OFC). The remaining countries (23/89) had data largely based on parent-reporting of a food allergy diagnosis or symptoms, which is recognised to overestimate the prevalence of food allergy. URL_0",
"One reason for the increase in allergies is that we are suffering from increased Gut Permeability. Common pain relievers and anti inflammatory drugs work by inhibiting the COX-1 and COX-2 enzymes. Unfortunately COX-1 also creates the mucus that protects your stomach and intestinal linings. Overuse of COX-1 inhibitors like Ibuprofen cause problems in your gut where food particles like Gluten that are typical not absorbed into your body are now directly entering your blood stream. So this is like if you have a broken turnstile at a train station where just anyone can walk in now. The overworked security keeps runs around trying to clear everyone out without a valid ticket but will eventually start profiling and then specifically accost everyone wearing a hoody for instance. Unfortunately our other common class of anti inflammatory is steroids. Steroids like Cortisone are commonly used to treated inflammation but have the side effect of suppressing the immune system. When the immune system comes back from being suppressed it can then be extra sensitive causing the body to develop allergies that it hasn't had before."
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nki9o2 | Is the cut-down hashrate on the new GPUs going to affect performance in usual tasks? | As far as I remember, this was created to limit mining performance. If this cut-down is not going to affect performance in usual tasks like video editing and gaming, why do GPUs have it in the first place? | Technology | explainlikeimfive | {
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"Hopefully this ends up being close enough to ELI5. As far as I know the hashrate limiter in the rtx 3060 was made in software only. More accurately with the GPU driver. I don't yet know how nvidia will end up implementing the same limiter in the upcoming versions of the other 3000 series cards, but my bet is that it's still mostly done on the software side. Basically the gpu driver is detecting a specific type of computation and in such instance throttling the performance. By the way this only applies to the hashing algorithm used by ethereum. Other algorithms shouldn't be affected. Nvidia's argument for the restriction is that that there would be more gpu's available for other users (eg. gamers), as miners would gravitate towards other cards. The more probable reason is that they will be also coming out with a miner specific line of cards. So in the end it's about squeezing more money out consumers.",
"No, they work by trying to detect when someone is specifically using the card for mining, and only reducing performance at that point. So it’s not like they just built the card and cut out a part that lets it mine, they just tried to make it smart enough to know when to throttle itself so it would be worse at mining. A lot of the same functions that make GPUs good at mining also make them good at all the other tasks people use them for. That’s why people switched to GPUs for mining in the first place. So you couldn’t realistically remove that functionality entirely without actually impacting performance on other tasks. So instead they just tell it to look out for anything they don’t want you doing and then cut performance across the board while you’re doing it. They say it’s unhackable, but that’s almost certainly not true. We didn’t really get to find out though since Nvidia released a test driver by mistake that didn’t include the limiter. So no one needed to make their own work around once they could get Nvidias. They are trying again with new cards soon, so maybe this time it’ll last a little longer."
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nkiv1e | What does "biodegradable" packaging really mean to the end consumer? Can we stick them in our flower pots? | Chemistry | explainlikeimfive | {
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"Short answer, no. 'Compostable' is the one that breaks down and can be beneficial to the soil - or at least not harmful. 'Biodegradable' means that it will break down into tiny pieces, but it can take years and years and it's just means it's a smaller version of what it once was - usually little bits of plastic, which is now in the ground. Not beneficial.",
"Yes, for the most part they would, but it wouldn't be quick. When biodegradable items end up in a landfill, they are degraded by bacteria, mould, fungi and the like in around 6 months, but they're not effective fertiliser. More just an alternative to it lasting for centuries in a landfill.",
"Biodegradable means at least one organism (maybe bacteria or a fungus) can break it down. There is no organism that can fully digest plastic yet so it is not considered biodegradable. Also, just because something is non-biodegradable it does not mean it’s bad for the environment. Some chemicals will immediately degrade upon contact with water or sand but no organism can degrade them into their components (silicones are a good example).",
"Good questions! I’m not an expert, but I do know that “biodegradable” and many other terms that imply eco friendliness have pros and cons. Biodegradable products break down much faster (6-9 months) than other types of products. Biodegradable products are mostly made of sustainable materials that break down into carbon dioxide, water vapor, and organic material, which aren't harmful to the environment. If biodegradable products are buried in a landfill where they receive no oxygen, they emit methane gas, which is bad for the environment. Items marked “biodegradable” should be disposed of at a commercial compost center (they’re more capable of biodegrading material than a home compost pile) or recycling facility. Incinerators convert biodegradable items and other waste into toxic gases."
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nkki4f | How are videogame codes protected ? | Let's say you download a game and can play it offline. In theory, everything you need is on your computer, right ? So how come people don't just find everything, copy it and massively share (or sell for a lower price) folders with everything in ? | Technology | explainlikeimfive | {
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"That's how pirated copies work, essentially. Not quite as simple as a copy & paste, of course. Games, like every other program, need to have what you could call an \"entry point\". It's a program or a function that needs to be executed to start the game proper. The entry points of games have protections installed in them that run certain checks to make sure the copy is legitimate before starting the game. They can look into windows registry, they can contact a central server, whatever. If they don't like what they find, they won't load the files and they won't start the game. That's the DRM. That needs to be bypassed for an illegitimate copy of a game to be able to start. Not all games have DRM, and those can very easily be copied and shared. edit: engrish",
"Your title and description mean two different things. For video games that are made in C++, you would need to disassemble the executable file and try to read the machine code ( which is incredible hard as most of it is just nonsense that's unreadable ). This alone takes up too much time so unless there's a BIG incentive for the hacker to do so, ( adding viruses to the crackedware and stealing your $$$, etc ), no one will do it. You can't just share game files with your friends even if you can play it offline because most of them have basic authentication that prevents you from doing so. Something simple as checking your PC HW ID, etc. No one sells cracked games because no one is stupid enough to buy them. ( Please don't confuse this with G2A, etc. Those games are not cracked. Most of them are official games with official accounts or stolen keys that lets you play them... ) Most of the cracked games you see on torrent are riddled with viruses. Even the top torrent users have been caught riddling their \"free, crackedware\" with viruses.",
"I see a lot of wrong answers here a) DRM protection: Games that will only run when a certain key is entered (it can be bypassed with enough time and effort) and games that will only run when launched through a service like steam. b) Connection requirement (for online games): If the client appears to be modified in anyway then refuse all requests for a connection to game servers. DRM protection can be byepassed, that's why you can find pirated copies of almost all games DRM free games like GOG-games can be shared just by sending the installer to someone else, even though it's not ethical to do so"
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nkkn9z | Psychologically, how does lying reduce critical thinking among humans (i.e. authorities spreading lies to its citizens)? | Other | explainlikeimfive | {
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"Lies themselves don't reduce critical thinking. Lies actually probably encourage critical thinking! However, critical thinking is a skill that must be taught, and authorities that placate their subjects with lies often also tend to strictly regulate systems of education so that the key skills of critical thinking are never acquired. Incidentally this is why questioning authorities is so often seen as subversive and even criminal in such societies: questioning is a fundamental aspect of critical literacy. The message is that good citizens don't ask questions, and when that ideology is deeply rooted enough, it works.",
"It doesn't reduce the thinking ability, but as the saying goes, \"Garbage in, garbage out\". If your facts and premises are incorrect, then applying perfect logic to them will not result in factual results. Your results will be *valid*, in the sense that you have used proper logic with them, but they will not be *correct* in the sense that they correspond to reality."
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nkl2b0 | can anyone explain me the butterfly effect? | Physics | explainlikeimfive | {
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"Most people here have the wrong idea of what the butterfly effect really is. Sure, small actions can have huge consequences, but that's not the point. What it really is about is that tiny changes in the initial conditions of a system can result completely different outcomes. This particularly true with chaotic turbulence and weather. When doing the calculations, just rounding up a single decimal point can sometimes lead to predictions completely different from the more precise calculations. That's why weather is very unpredictable from more than 3 days out. So, no, a butterfly cannot cause a hurricane, but it can potentially result in the hurricane landing in one place instead of the other.",
"Think of a Roulette wheel. You can try duplicating the exact spin of the wheel and launch of the ball by hand but you'd never be able to achieve the same result. This is because little changes propagate and become bigger and bigger differences in any complex system. The smallest degree difference, the slightest difference in timing, the slightest extra torque in the spin will guarantee a different result. So you have predictable Newtonian physics where if you knew the location and momentum of every atom you could predict the result. However Heisenberg's Uncertainty Principle says that we cannot determine both the position and momentum of a specific particle accurately - therefore it impossible for us to accurately predict the exact interactions of molecules. And so Newtonian Physics when combined with Quantum Mechanics gives us Chaos Theory. So a butterfly flaps it's wings - the air molecules being moved interact and cause other air molecules to move that can chain effect other molecules and where the beginnings of a breeze were about to go in one direction now it goes in a slightly different direction. That breeze combines into other airflows and combines into effecting bigger and bigger movements of air. Now conditions might have been hovering on developing a hurricane out in ocean. A slightly different wind could now trigger the hurricane to occur where it may have dissipated before. The idea is if the butterfly hadn't flapped it's wings the seemly random events of the wind and weather would have turned out differently.",
"The scientist and mathematician Edward Lorenz was studying long-range weather forecasting with a computer simulation. One day he ran a weather simulation that had a start value of 0.506127, but when he reran it he decided to just enter 0.506 because he assumed that the last three tiny digits wouldn't make much difference. He was very surprised to see that while the weather in the simulation started off similar, soon it diverged completely into different weather. He realized that weather has \"sensitive dependence on initial conditions\" — a tiny difference in weather at the start would result in huge changes down the line. As a poetic example, he later wrote that the flap of a butterfly’s wings in Brazil could later set off a tornado in Texas."
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nklb46 | Noise cancelling headphones: how can sounds waves disable other sound waves? Is it possible that before the external sound wave travels the space between my headphones’ external microphone and my ear, my device has enough time to produce a sound wave that perfectly cancels it out? | Technology | explainlikeimfive | {
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"Sound is pressure waves. And when one sound wave creates low pressure and another creates high pressure they end up canceling each other out in that perticular spot where they cross. The noise cancelling headphones just make sure that the spot where these waves cancel is right at the entrence of your ear canal. They are able to do this because the microphones are much farther away from your ear then the speakers and electricity travels almost instantanious while the speed of sound is much slower. The headphones may still employ techniques to predict the noises before they happen by analyzing the frequency and the rhythm of the various noises it picks up.",
"Yes. Without too much difficulty given modern microprocessors. Sound travels at about 300m/s. So this is 30,000 cm/s. If the external microphone is 1cm from the speaker, then the noise cancellation has about 1/30,000 s. A simple microprocessor can easily run at an instruction for each 1/10,000,000 of a second. So a microprocessor can execute 330 instructions in the time it takes sound to travel 1 cm."
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nkny0h | if gold bullion is a good investment, why do companies sell it? | Why do companies like Bullion by Post sell precious metals if they are really a safe investment? They're prices are usually quite close to the actual market value and if they buy gold from people I presume they are giving a relatively good deal. | Economics | explainlikeimfive | {
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"The best way to make money in any market over the long term is to broker transactions and take a piece of every trade. Price goes up and some people buy in while others take their profits off the table - great, charge them both for every sale. Price goes down and some people scoop in to pick up a bargain while others cut their losses - great, charge them both for every sale. Either way, you don't get stuck with the asset itself, and you're largely immune to short and medium term trends. Some precious metal dealers maintain a small inventory which they use to be on one or the other side of a trade, but for the most part, even that is designed to be a way to bring buyers and sellers together rather than an actual investment the dealer uses to make money. It's more nuanced of course, but better to make a buck on each of 10,000 hundred dollar trades every week (whether prices are rising or falling) than than buy a million dollars worth of assets today and hope you can sell them for $1,010,000 next week.",
"You can't spend gold. You have to sell it eventually in order to make money. They have already invested it.",
"Most of the cost of sending someone a gold bullion is in aquiring the gold. However there is a small markup which goes to things like postage, package, handling, storage, and profits. Looking at their prices they take around 5% markup depending on the product. And when they are dealing in high value stuff like gold this is quit sigificant to pay all the expenses and give them a nice profit on top. As for why they are not keeping the gold for themselves they do not have the money to own the gold. They loan money from the bank in order to buy the gold they sell you. If they do not sell the gold they are just stuck with the storage fees and the loan interest. There are companies which will do this for you and you can buy a gold certificate saying that the gold is safely stored in their vaults which is much cheaper then shipping it out to everyone. However that would be a completely different way of making money with different fees."
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nkooxa | How is good cholesterol, like that found in eggs, better for you than what's found in beef fat? | Biology | explainlikeimfive | {
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"No, you got this wrong. Cholesterol is cholesterol. The \"good\" and \"bad\" cholesterol doesn't have to do with cholesterol itself. The \"bad\" cholesterol is how we call LDL particles in our blood. It's cholesterol, fats and some proteins packaged together, and it's purpose is to deliver those fats and cholesterol to our body's tissues. When there's too much of it, it sticks to the walls of your blood vessels and cause atherosclerosis. The \"good\" cholesterol is how we call HDL particles that take this unnecesary cholesterol and clean it out of the bloodstream."
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nkqu4y | How did primitive humans, with a top speed of 28 mph, hunt large mammals like deer, bears, wolves, etc, that can reach speeds of near 35 - 40 mph? | Biology | explainlikeimfive | {
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"1. Tools: Primitive humans could sharpen a stick to make a throwing spear, and build sharp points from things like flint, wounding or killing an animal from a distance. Also: Slings, throwing rocks, building traps, and fire. There is a place in Alberta, Canada called (charmingly) \"head smashed in buffalo jump\" which is where ancient native americans would chase herds of buffalo off a cliff, where they would fall to their deaths. Then the natives could just walk around to the base and collect meat, hides, and all the other resources at their leisure. 2. Endurance: No other animal on earth can run as far a human. World champion race horses have to rest for days to recover from a single race. Humans can routinely run marathons, 42km, with training. There are several cultures that still exist that use endurance chases to corral prey animals into traps or kill zones. 3. Stealth: It's hard to imagine for a \"civilized\" person, but humans can be extremely stealthy in the wild with proper training. Getting close to an animal allows you to kill it before it has a chance to run. 4. Teamwork: Just as a pack of wolves or lions can bring down much larger prey, ancient humans could co-ordinate better than almost any other animal using perhaps our best tool: language. Surrounding an animal, tiring it out, and only when it's weak going for a kill allowed ancient peoples to bring down huge animals, like mammoths. I would like to add that hunting predators like bears and wolves is rare, because often they don't run AWAY but fight back. Also generally the meat of predators isn't great to eat anyways.",
"Most animals can outrun humans, but only for short distances. Humans run slower, much slower, but we can go forever. There is no marathon running in the animal Kingdom, but if there was humanity would be champ. Ancient humans would track animals through the bush, the animal would run away, and the primitive humans would just lope after it. The animal would get scared run, and the humans would run after it again. We also had the brains to track it. Rinse and repeat after 6 hours and that fast gazelle is too tired to continue anymore. It's now dinner. Basically, it's like zombie movies, but to animals we're the relentless zombies. Later on, as our brains developed, we did as humans do and use our brains to save on effort. Why chase an animal when you can set a trap? Later on still, clever humans discovered animal husbandry. Now we only use our long-distance skills to hunt 26.2 stickers for our Priuses. Edit: when I say \"we\", I refer to humanity. I am not *personally* optimized for running.",
"the video \"[Are Humans OP?]( URL_0 )\" covers the topic others have mentioned in an entertaining way.",
"Three main factors. 1) as stated by others, we outlast them. We're are the terminators of the animal kingdom. We will keep on coming, sand rubbing after them until they drop from overheating. 2) ambushes. We sit, and wait by watering holes and trails, and dens until they pop out. Then when.. Dinner. Most predators do this. 3). We can throw things. We can throw very well, and at high speeds. This is a trait no other animal has, and is very effective even if you're just chucking a pointy stick. Once we got better with tools (bows, slings, etc) it's game over",
"Endurance. Humans didn't tire as easily as other animals. say a deer can only run so fast for a short amount of time, so eventually they would tire out and become exhausted, while the human was able to keep going and catch up.",
"People have three big advantages: smarts, spears, and stamina. Most importantly, people are smart. We can set traps and make tools, but just as importantly talk and plan hunting strategies and pass on lore about animals. And we can mentally model what our prey is thinking, allowing us to predict their moves. We can plot to circle around the deer or drive it off a cliff or spook it toward another hunter. Also importantly, people have spears. We can throw very well, so we don't necessarily have to catch an animal outright, we can hit it with something pointy. This is also useful for staying at a distance from dangerous prey. And finally, we have stamina. People aren't the very best endurance runners out there, but we are pretty good at it. Many species that can evade us over short distances can be caught up to over longer ones. These are not entirely separate factors. Brains obviously help us make spears, but they also help us persist while hunting better...we can keep on a goal even when we no longer actually see the prey, and intelligence lets us track better. And it lets us do things like invent water skins or hollow ostrich eggs to keep hydrated during the heat of the chase. Similarly, there's not necessarily a clear distinction between hunting with a spear and persistence hunting...it might take some pursuit to get close enough to hit your prey with a weapon, or prey might run after being wounded and need to be tracked down.",
"Stamina and tracking. There's a video on YT narrated by Attenborough, part of a series called \"life of mammals\" shot in the Kalahari where a group of guys run down a Kudu over a couple of days on foot. Shows much of what people are saying here in a single video. Edit: it was 8 hours",
"Pursuit Predation. Humans are interesting. We cannot sprint for long durations but we can job or walk quickly nearly forever compared to the rest of the animal kingdom. So, we would just hunt things until they were completely exhausted and then easily kill them in that state. Think of humans as the terminators of the animal kingdoms. Most animals can only sprint for a little while and its incredibly exhausting. They stop to rest, there we are again. So they go sprinting off again. Their lungs aching body is screaming. They stop. So tired. Uh oh here we are again. Rinse and repeat and boom we just killed a cheetah or something.",
"Wait what? Usain Bolts top speed isn’t even 28 mph. Who what when how? Working as a team is the obvious answer but wut?",
"Look up [persistence hunting.]( URL_0 ) (wiki link) Basically, over a long enough distance, humans can outrun anything. The other animals can *sprint* faster, but then they need to rest. Humans are terrifying because they can just keep jogging+walking+tracking as needed until the prey collapses of exhaustion."
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