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mcv8t2 | What are the difference between illusion, hallucinations, and delusions?? | Other | explainlikeimfive | {
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"Illusions show everyone something that isn't really there. Hallucinations are things only you can see that aren't really there. Delusions are thoughts in your head that aren't really true.",
"Illusions are usually trick of the brain. Your brain seeing things and interpreting them badly, or seeing something that is not entirely true. Either the brain fucking up, or other things playing trick on us. Example are seeing face in things that don't have them. It's an illusion our brain play on us usually when we see three holes aligned for eyes and mouth. It leaves a strange feeling of being watched. It's not a face, it's not drawn to be one, but our brains makes us believe it is. Same for mirages in the desert, but for the other half. We see something but that something is not entirely true, there is an oasis but it's not where we see it. The thing we see aren't fake, they're just not as we expect them. Hallucinations is slightly different. It's when something doesn't exist, and our brain entirely create it. There is usually little to no basis for them, and it's entirely our brain tricking us into believing something that doesn't exist is there. Example are seeing ghosts, or people tripping on drugs that see pink elephants. These are not real, have no basis on reality, yet our brain for one reason or another sees them. Delusions are completely different. They're not tricks on perception, but tricks in belief. A delusion basically mean that someone believe something that is false and simply refuse to see anything contradicting it. They're usually fixed belief that one simply cannot easily drop. These are really dangerous and are either self manufactured or someone manufactured them and planted them in you to control you. Some may say that religions or flat earth could be considered delusions in that regard. I'll let you decide for yourself. More concrete example I can give are people that strongly believe that a star or otherwise important person that they've never met and may only have crossed eyes with once truly loves them. This one is usually self created and simply prevent you from seeing the truth that they most likely just looked at the crowd of people you were in. Another example are sects. They usually prey on you at a moment you're emotionally weak and will simply sell you a delusion that will make reality easier to cope with. Like the idea that you feel sad because you own things and should give them to the sect so you'll be liberated. The usual sects example are most often selling a delusion and most of their effort are to reinforce them to make sure you don't break free. TL:DR: Illusion is when you see something wrong. Hallucination is when you see something that don't exist. Delusion is when you believe something wrong to a point it's unhealthy.",
"Illusions - tricking your brain into seeing something that isn't there. Optical illusions work on everyone, they're not a sign that there's anything wrong. An example is [this one]( URL_0 ) where it looks like squares A and B are different colours but they're actually the exact same colour. It's just a result of the way the brain perceives colour. A hallucination is specific to an individual. If I'm hallucinating something, you can't see it. That's because it's created entirely within the brain, and not the result of a certain image being made to trick you, or of weird optical phenomena. Note that hallucinations aren't always visual, they can be auditory as well. I've had auditory hallucinations after waking up, they're freaky but not that bad. A delusion is a long-term consistent false belief. A common one for people with schizophrenia is that they believe that they're being followed or watched (e.g. by a government agency) even though there's no reason for them to believe that and nothing to suggest it's true. A key part is that it's actually firmly held despite evidence to the contrary. Someone just claiming to believe something weird isn't a delusion, nor is somebody being tricked into believing something by a dishonest person. If somebody believes the Earth is flat because they think they've seen evidence supporting it--even if the evidence is bad, it's still something they considered and came to using logic, albeit faulty logic, whereas a delusion in the context of mental illness is usually completely divorced from any sort of logic or evidence."
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mcvoep | How do bees avoid stinging each other in the hive? | Biology | explainlikeimfive | {
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"A bees stinger is inside them by default. They have to actively try and sting something to do it. So a bee just walking around won't sting everything, honey bees specifically won't even sting a human most times unless you attack the hive or try and aggravate them.",
"Think about it like humans with umbrellas with the fancy u-shaped handles. We can chose to try to hook people's arms and legs in the u-shape, or not. Similarly, bees can chose to sting something or not Weird analogy, but hope it works lol"
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mcvvah | Why do muscles shake when tired? Doesn’t that take even more energy? | Biology | explainlikeimfive | {
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"The basic mechanism that causes muscles to contract is very similar to a person reaching out their hand, grabbing on to a rope, then hauling on that rope. If you want to picture how a muscle contracts, imagine a bunch of boats lined up front-to-end in a lake, with a group of people in the front and back of each boat, and each boat connected to the one before (and after it) with a rope. The ropes aren't tied to anything, the people in the boats are holding on to them like they were going to play tug-of-war. (the people in the front of one boat are paired up with the people in the back of the one ahead, and so on) Suddenly someone gives an order, everyone pulls smoothly (nobody screws around and plays actual tug-of-war, they're cooperating) and the whole line of boats gets shorter - no one boat has enough rope to make a big difference, but if you have 10 boats with 20 feet of rope between each, and they all pull, the first and last boat will end up 180 feet closer together. If nobody screws up. Now, imagine that everyone is tired after doing this for a very long time, and someone asks them to do it again. Some people are distracted and miss the orders, others are so tired their grip slips and they barely manage to grab the rope again, in one of the boats someone starts throwing up, etc., and they just barely manage to pull the boats together, but it's really slow and sloppy and uneven. That's the \"shaking.\"",
"Think of your muscles like a shitload of pulleys inside you. When you're tired, some of the pulleys stop pulling as hard as the others, or fail to pull at all. The ones that do still work don't move and shake at the same time.",
"That \"shaking\" is not being able to pull 100% of the time and instead firing only part of the time, as much as it can. In the spirit of ELI5: It's like when you're drinking through a straw and get to the bottom of the cup. You go from \"nice smooth silent drinking\" (100% \"on\") to a spluttering on-and-off \"shaky\" flow. That flow is NOT drawing more liquid than the smooth drinking was, it's sputtering out to nothing.",
"You’re thinking about it the wrong way. It’s not that you’re shaking because all of your muscles are suddenly pushing/pulling really hard, you’re shaking because some of your muscles have stopped while the rest kept trying.",
"Muscles contract when a certain neurotransmitter (acetylcholine) activates the muscular cross bridge. Briefly, acetylcholine allows calcium to enter the muscle cell, alter the ‘shape’ of the muscle cell, and something called a power stroke occurs. This leads to muscle contraction. When you’ve completed a very hard workout, the buildup of acetylcholine is too much for its enemy (acetylcholine esterase) and you end up with an altered signal within the muscle, leading to extra twitches or even muscle cramps. PS: just because I’ve seen it mentioned a few times in the comments, it’s not lactic acid. Low pH leads to pyruvate turning into lactate, but that is to maintain functional pH levels. Lactate is actually incredibly beneficial to exercise, not only serving as a pH buffer, but as another substrate to be turned into glucose via the Cori Cycle. Also, lactic acid is typically fully restored to baseline within 30 minutes of ceasing exercise.",
"Muscle contraction takes energy. When muscle runs out of energy, muscle stops contracting. Muscles dont all contract at the exact same time. When some bits of muscle fail because no energy, others still have some energy, so they alternate failing and recovering and contracting again. You feel this when you do a long plank exercise."
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mcw0zn | What's the difference between gentrification and investing in poor and minority neighborhoods? | Other | explainlikeimfive | {
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"The difference is who lives in the housing. If the neighborhood population is displaced by the property owners, that's gentrification.",
"investing: better schools, better public areas, roads, etc. anything that locals can use gentrification: building expensive buildings (shopping malls, restaurants, houses) that locals can’t afford to use. That can lead to more valuable land and higher rent required to live in the are, which locals also can’t pay, so they stop living there",
"Think about who the changes are aimed at/meant for. Think about who benefits most from them. That’s the difference. Investing in a neighbourhood means creating services and amenities that the people living there get good use out of. More green space for their kids to play, better access to essential shops, community hubs like libraries and schools, good housing...that sort of thing. Gentrification means creating services and amenities that people *who do not live there* use more, changing the area specifically to be more like what these wealthier incomers want rather than looking at what the locals need. Imagine building housing that no one already living there can afford to live in, or converting a grocery store (one of very few in the area) into a fancy coffee shop and forcing the locals to travel further out to get what they need. Whose needs and wants are being prioritised?",
"There is no difference. Any increase in the neighborhood that makes it better will also make it more attractive to the masses. Which raises property values."
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mcwutr | why do you suddenly sweat when you are in an intense amount of pain? | From stubbing a toe all the way to giving birth, why is it the body’s response to sweat when it is inflicted with pain? *why is sweating a response to pain? Edit: clarity, simplifying the question | Biology | explainlikeimfive | {
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"Not an expert, but I believe it has much to do with the release of stress hormones (cortisol and adrenaline) in the body. Typically, these hormones cause a good deal of sweating - such as when you are suddenly very nervous/scared or embarrassed. It would make sense that, upon the occurrence of a high level of pain, the body would assume an injury. As such, hormones like adrenaline are useful in controlling bleeding and aiding survival and flight from danger. I believe this is all controlled by the autonomic nervous system, which initiates those processes without any conscious effort from the person."
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mcxdto | If soundwaves are compression waves in air molecules, and thermal energy is vibrations in air molecules, why aren't loud things hot? | Like if I have a really bright flashlight I can feel heat from the beam, but I can blast a speaker at max volume and I might even feel the vibrations in my hand, but there's no change in temperature. Is this a glitch in the matrix? | Physics | explainlikeimfive | {
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"Being hot is a molecule vibrating chemical bonds but not translating in space (a little but not much). A compression wave is a whole bunch of molecules translating back and forth together. Hope that helps!",
"Sound energy will cause temperature rise but it will be hard to measure outside a controlled experiment in a lab. One reason is that most of the time, it isn't a lot of energy converted to heat in the air and source of sound isn't high energy to begin with relatively speaking. A 50 W sound system might drive a speaker to produce a few watts of actual sound energy and, in a regular room, that is pretty loud. Loud enough that most people won't tolerate it. It would be hard to detect a temperature difference even if these few watts converted to heat. Most of the heat would come from the electronic equipment, the lights in the room, the body heat of people inside - all of which release much more heat into the room.",
"Actually ultrasound can heat tissue slightly and you can produce high heat with high intensity ultrasound [ URL_1 ]( URL_0 ). It is due to absorption of sound waves in tissue but I am not sure that is the mechanism you are talking about",
"There are 3 factors here. * The sound wave itself doesn't add much energy. The individual molecules are already bouncing around at the speed of sound. The fact that a wave is moving through them doesn't change their average velocity by an appreciable amount. (But in extreme cases it can. Look up [acoustic refrigeration]( URL_0 ).) * Sound isn't just compression. It is also rarefaction (low pressure) between the high pressure peaks. The transfer of heat (ignoring radiation) is based on the number of collisions between air and the object. While the high pressure regions have more collisions the low pressure regions will have less. This averages away much of the effect that you might expect. * If you can feel the vibrations then it is producing heat in your hand. (Any time something deforms there will be heat generated.) However it is an extremely small amount of heat and is too small to notice."
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mcxvg3 | Why do people act weird after waking up from anesthesia? | Biology | explainlikeimfive | {
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"Hi there! Nursing student here, general anesthesia is a drug regimen that includes a couple different type of drugs. It works on the central nervous system to put the patient to sleep. All vitals will trend down and the patients pain response is rendered useless. The patient, usually, has no idea what’s going on. Waking up comes in three stages. First you have the uptick in vitals and maybe some groaning from the patient. Second stage is where your question lies. They’re still under the effects of the drugs so their minds aren’t really connected to reality yet. They may be calm or become violent because they’re still unsure what has happened to them. (Of course they know they went into surgery, but they may not have connected the dots). The third stage is where the drugs are mostly out of the system and the patient is coherent and responsive. Basically it’s like one big high. It alters the mind processes, much like opioid medication. Let me know if this explains it, if not I can go into more detail."
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mcy3ot | when we remove earrings or piercings after sometime what’s that gunk/buildup on the piercing? | Biology | explainlikeimfive | {
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"Skin cells, skin oils, dirt, sweat, cheetos dust, mucus; basically whatever your skin comes in contact with, it can collect there."
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mcyby3 | The point of crypto? | How is crypto more secure than cash or credit card or paypal? Literally anyone could see every transaction you make and how much money you have. Thats creepy as shit | Technology | explainlikeimfive | {
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"It is possible to see every transaction and how much money is in every account. However there is no reliable way to connect an account to a single person. So while you can get very detailed information about an account you do not know who controls that account or which accounts are controlled by the same person. In addition to this there is no central authority that can accept or deny transactions as they please. That power is distributed over all the miners. So if some authority decided to manipulate which transactions are accepted it would be much harder to do with cryptocurrency then with traditional banks."
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mcz6ac | Why do we instinctually shake our hands when we hurt them, like when we punch something? | Biology | explainlikeimfive | {
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"Okay. So when you hurt your hand, nerves send signals to your brain that somethings wrong. We perceive that as pain. When we flail our hands, your nerves feel more stimuli, drawing the affects of pain away from your brain. To dumb it down even more. Shaking your hands is essentially **masking** the pain with more nerves sending signals.",
"The nerves that detect pressure in your skin/muscles are almost right on top of the nerves that detect pain. Shaking your hand is almost like squeezing your thumb when it gets hurt. The pressure signal somewhat blocks/ drowns out the pain signal. But I think as others have said, your brain can really only process so much at once, and unconsciously decides what it focuses on. For example, if your brush your tongue most people will feel a gag reflex. But if you do literally anything on top of brushing your tongue, you might notice less of the gag reflex. I heard pinching your arm is enough. I tap my foot to a beat or drum my fingers, but almost anything can have the effect."
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mczg1x | Firefighters, are there positions in the vehicle who are in charge of different duties? | Other | explainlikeimfive | {
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"Yes. The chauffeur (driver) is in charge or driving and if you’re in an engine company pumping the water. Riding shotgun is the officer who is in charge of the operation. They generally decide where the truck will be positioned in regards to the emergency and who on the rig will be in charge of what position. These positions depends on if you’re an engine company, ladder company or a mix. Every situation is different and depending on if you’re volunteer department or paid the amount of people available may be limited and certain duties may be combined",
"For our department the engine and truck are different. It is front passenger is the boss(Lt. or Capt.), driver is most senior guy behind him next most senior and behind the boss most junior. The driver will operate the pump panel and hook up to the hydrant. The 2 guys in the back will hash it out who will go with the boss with the nozzle into the building. The other will help hook up the hose and pull it around obstacles as he makes his way in to join up with the other 2. The truck has different tasks to be done. The boss and FF behind him will go into the building for search and rescue. The driver and FF behind him will put ladders at different places on the building for rescues or for escapes for the guys inside if they need to bail out. They can also set up the big aerial ladder if need be.",
"NYC firefighter here. Biggest and busiest department in the U.S. Other guys did a good ELI5, so I’ll go in depth! Every firefighter has an assigned position and duty based off the building and scenario. Officer and chauffeur ride up front, all other members ride on the “back step”. 2 face forward and 2 face backward. There are a several kinds of units but the 2 main ones are engines and ladders (aka trucks). Engines operate hose lines. Ladders do forcible entry, search, ventilation and other various things. Tactics and tools change based off the building type but here’s a general breakdown: ENGINE POSITIONS OFFICER: (lieutenant or captain) and commands unit CHAUFFEUR: drives and controls water pumping NOZZLE: directs the hose stretch BACKUP: positioned directly behind nozzle to handle the back pressure CONTROL: controls the amount of hose that is stretched LADDER POSITIONS OFFICER: (lieutenant or captain) commands unit and searches for the fire CHAUFFEUR: drives and positions ladder attached to the apparatus ROOF: proceeds to roof and performs ventilation or life saving rope rescue OUTSIDE VENT: generally works on the exterior positioned opposite the hose line to vent windows or rescue life hazards IRONS: forcible entry with an axe & halligan, then search for life on the interior. CAN: water extinguisher & 6 ft. Hook. Stays with the officer to find the fire and search for life Upon receipt of a call for fire, 3 engines, 2 ladders and a chief are dispatched. Upon confirmation of an all hands fire, additional units are dispatched. Here’s the scenario for a fire on the first floor of a fully detached 2 story private dwelling: 1st engine on scene: starts stretching a hoseline into the house, to the seat of the fire. 2nd engine: assists the first engine 3rd engine: starts stretching an additional hoseline where it’s needed 1st Ladder on scene: performs forcible entry if needed, finds the seat of the fire and then searches for life (civilians). After that, they’ll start breaking windows for ventilation and then overhauling (demo-ing) the walls and ceilings to the find fire extension. 2nd ladder: similar to the first ladder, except on the floor above. Smoke and heat go up, so the risk of a life hazard could be even greater. Chief: stays on the exterior and monitors and commands the whole operation. It goes significantly deeper than that, but a lot of that info would be lost on a non-firefighter. That should about cover it.",
"I'm coming from the wildland fire side of things, so we run things a little different than the structure side and it can even vary among those of us running engines in wildland. Personally, as an Engine Boss, I usually have one of the more senior firefighters drive. This is someone I trust behind the wheel and that has some local knowledge about wherever we are, this is mainly so they know exactly how to get us where we are being dispatched too. I usually ride shotgun to handle radios and help navigate and direct the driver. This changes up if I have a trainee Engine Boss on my engine. Then, I usually drive and let them ride shotgun and handle all the radio traffic and run the show (ya know, to an extent). New folks pretty much always ride in the back, just the way it is. Usually, enroute to an incident, I'll start delegating roles to each person in my engine, and this will change depending on what we are being sent to. Rolling on an aircraft crash is WAY different than a campfire creeping out of its fire ring in an established campground and will require different people grabbing different equipment when we get out of the rig.",
"In a standard 4-Man engine Crew (in my city) you have: Engineer (person who drives the apparatus): their job is having the apparatus and equipment ready, things like charging the hose or setting up tools for extrication/rescues Captain (sits in the front passenger seat) is in charge of operations of his engine crew. Usually starts paperwork on medical aids. Sometimes also a paramedic In the back you have: Firefighter Paramedic: Usually only 1 medic per engine but sometimes there are more. They are usually the highest medical provider on scene and establish initial patient contact until transporting paramedic ambulance arrives Firefighter EMT: FF Paramedic's partner. Both the back seat firefighters are gonna be doing the manual labor part of the work, extrications/medical aids/going interior on fires, using the hoses"
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mczg8s | ; why do binary letters start at 65 (01000001) with uppercase A? | I am curious | Technology | explainlikeimfive | {
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"It's part of ASCII Encoding. One thing with ASCII encoding is that the upper and lowercase letters have a perfect offset. A = 65 = 01000001 a = 97 = 01100001 You can see they're offset by 32, which means a single bit can be changed to easily flip uppercase to lowercase. If you wanted to go Upper to Lower, you just had to do `OR 00100000`. Similarly, if you wanted to go lower to upper, you just had to do `AND 11011111`.",
"There are other characters before the A, 65 of them in fact including 0 (Null). These characters are important in various ways other than simple text; things like \"Start of text\" (2), \"End of text\" (3), \"Negative acknowledgment\" (25), \"Cancel\" (30), etc. The list continues and at 65 it gets around to \"A\".",
"Because ASCII (American Standard Code for Information interchange) put 64 other characters/symbols before “A” for a reason best explained here: Wikipedia > ASCII > History section > internal organization subsection."
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mczq2m | How much water would there need to be on Earth before the crust starts to liquify? | Earth Science | explainlikeimfive | {
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"That's not how rock works. If you add water to the Earth, land floods. Under the water, the granite mountains are still granite, just under water. It's not going to liquefy unless the rock gets hot enough to melt."
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md0d07 | Why does Russia own a random chunk out of Lithuania and Poland? | I cant seem to google the right thing for the answer. I'm playing a little mobile game, guess the countries (because I low key thought Cuba was in Africa) and was brushing up on it and I noticed. | Earth Science | explainlikeimfive | {
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"If you're talking about Kaliningrad, that was a part of Prussia and then later a part of Germany that the Soviet Union claimed during its offensive westward against Germany. After the war, there was a conference on the fate of Germany and how certain territories should be split up, and the Allies agreed that the USSR could keep that territory for itself.",
"Germany used to be a lot bigger back in the day. Their border extended to the edge of Russia and included the part of the world now known as Kaliningrad. The Germans called it Königsberg. It's important to note that neither Poland nor Lithuania existed as independent countries at this time, both were part of the Russian Empire. Germany lost World War 1 despite defeating Russia. The peace treaty lead to the creation of Poland as an independent country again, and the powers that be decided to give it a port on the Baltic Sea. This meant that Germany was split apart to create the \"polish corridor\". Königsberg became a German exclave and Poland got access to Danzig (now Gdańsk) Then Germany started World War 2 and invaded Poland and later Russia (then called the Soviet Union) again. This time the Russians beat them. After the war, the Russians decided to keep Königsberg and ousted all the Germans still living there. When the USSR fell apart, Poland and Lithuania became fully independent countries again (no longer Soviet puppet states), but Kaliningrad remained part of Russia proper.",
"Kaliningrad is an exclave - a part of a nation that has no direct connection to that nation's contiguous border. Exclaves and their special cases enclaves are pretty common in areas where borders would historically change frequently or where a specific geographic feature holds more strategic importance or value than the surrounding land. They are typically pretty small, but Kaliningrad is one of the bigger ones, so you were able to easily notice it. Some cases can make your [head spin]( URL_0 )!",
"Kaliningrad was never polish, and only vaguely related to Lithuania, a long long time ago. In the early Middle Ages it was settled by Baltic tribes which were related to Lithuanians. After the crusades german knights took over and the area became more Germanised. Poland/Lithuania never annexed the land, they left them mostly autonomous. Eventually some more German Germans inherited the land and made the kingdom of Prussia which first ate a bunch of Poland then created Germany. It was only after world war 2 that Germans in general were “encouraged to leave” from the area by the ussr and the area has remained in Russian control ever since. So I guess the only reason Russia owns it is because nobody is claiming it because a) it was German land and Germany doesn’t want anything to do with world war 2 related land and b) Lithuania and Poland don’t really have a claim to it other than geography and even then probably wouldn’t agree how to split it"
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md0tsw | Why anti-inflammatory help if inflammation is a natural process of our bodies? | Biology | explainlikeimfive | {
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"Well, you said it right - inflammation brings more blood and therefore nutrients to the area. It also brings the immune cells to deal with the infection and to start the repair of the damaged tissue. But the problem is that inflammation needs to be regulated. If inflammation lasts for too long, it can actually damage the tissue instead of repairing it. In a healthy person this doesn't happen, since the body has it's own means of regulating inflammation but if these regulatory processes fail for some reason, there can be a problem. And that's where we need to come in with anti-inflammatory drugs. And, yes, pain is a good thing in the way that it tells you not to move with the injured limb but when you already know not to do that, excesive pain is unnecesary. This is a very brief explanation and it's by no means perfectly acurate - immunology is a very complicated topic."
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md11jj | If the sun does explode in the far future, what would make it explode? | Physics | explainlikeimfive | {
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"Stars generate energy in their cores, and this inflates the rest of the gas in the star like a giant balloon. More massive stars produce more energy and inflate to incredible sizes - near the ends of their lives they can inflate to preposterous volumes larger than Mars’ orbit. Large stars explode when their core suddenly stops producing enough energy to keep the rest of the star inflated. They collapse inward at hypersonic speed and the catastrophic shockwave when the innards of the star crumple into core obliterates it. The sun is too small for this, and will fizzle out with a sad stellar fart instead.",
"The Sun is a gigantic nuclear reactor. It produces a lot of energy, and in the case that gravity collapses the core, it can release a lot of it at once, in the form of expansion and explosion. Also our sun won't explode, bigger stars do though.",
"The sun is constantly exploding nuclear bombs by fusing hydrogen atoms together to form helium. The large size of the sun causes intense pressures and heat due to gravity at the sun's core, driving these reactions. When the sun eventually runs out of hydrogen to fuse, it will start fusing the helium products into carbon and oxygen. This reaction releases more energy than the previous hydrogen reaction, causing the overall size of the sun to expand due to the energy release. This generates a red giant. Once the helium is all gone, the later reactions are not as powerful and eventually the energy released cannot balance out against gravity. This causes a sudden collapse in the star as gravity pulls it together. In some cases, this single rapid shrinking grants enough energy for one last fusion explosion: a supernova. Supernovas can fuse atoms into various other atoms, providing the building blocks for planets.",
"The Sun won't explode (aka supernovae), it't not big enough for that, but here the process. Stars like our sun have enough mass that the pressure at their center keep the material there. Meaning that the hydrogen they have in their core stay there and that they will only be able to consume the fuel they have in their core and not the rest in their outer layers. Stars are in an equilibrium between two forces. The first is the gravity of their own mass trying to squeeze the star inward, and the second is the nuclear fusion that create an outward force. But when a star consume all their hydrogen in their core, the fusion inside stop, and without a outward force, gravity win. The core of the star is squeeze more and more and since it take time for the residual heat to get out of the core (it can take millions of years), the core of the star actually go up in temperature. This heat up the outer layers and like you probably know when something is heat up it become bigger, so that's what the outer layer does. It grow to massive since and we call the star at that stage a Red Giant. Now as the core of the star get compacted more and more by the gravity, the temperature rise enough that it can now fuse the helium in the core. Fusion start again, the outward force come back to fight back the graivty. The core get bigger absorbing the heat from the outer layer and the star is not a red Giant anymore, it goes back to looking more like it used to. But eventually the helium get all consumed and the cycle continue. The core get compressed by the gravity, the star grew into a Red Giant, eventually the temperature in the core get high enough to fuse the next element. Each time the star get bigger and then smaller and then bigger against, it will launch material into space, slowly losing mass. Eventually, the mass of the star isn't enough to keep the temperature in the core rising, so nothing happen anymore. Usually at this point all the outer layer was blasted away in space and what is left is just a naked core called a white dwarf. That's what will happen to our sun. If the star is massive enough, the cycle don't stop. The core keep rising in temperature and fusion happen with bigger and bigger atoms until you reach Iron. Iron is important because it's the first element that absorb more energy than it release when fusion happen. So now instead of nuclear explosion that create an outward force, the core start to suck all the heat from the star. Suddenly nothing is stopping gravity, no more fusion to keep the star stable. The star collapse under it's own mass. The only thing left that stop that collapse is a force that stop neutron from occupying the same space. The collapsing star smash into that force like a car would crash into a wall and this create the supernovea. But star can be so massive that even the force that keep neutron from occupying the same space is not strong enough. The star collapse on itself into a black hole. Something so dense that even light can't escape."
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md2ojv | I have noticed on newer cars that when the directional (turn signal) is on, the headlight on the coinciding side goes off. What is the benefit, if any, of this function? | Technology | explainlikeimfive | {
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"Turning off the bright headlight may make it easier to notice the turn signal, especially when it is otherwise dark out. I.e., If someone shines a bright light in your eyes, you may not notice any other lights near the light source.",
"It’s contrast. The turn signal contrasted on a darker background makes it appear brighter and more noticeable to other drivers.",
"A lot are already answering. I also believe there are federal regulations for how close a blinker can be to a headlight. Turning the headlight off allows designs where the two are close to pass this regulation."
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md3g04 | what this huge spike in the money supply economy means? | URL_0 | Economics | explainlikeimfive | {
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"The velocity of money is how much money changes hands. The velocity of money collapsed when the lockdowns started happening last year: URL_0 This meant that people stopped buying and selling a lot of things. In order to compensate for this, the Fed and ECB started engaging in quantitative easing, which increased the amount of money in circulation. The increase in money supply caused inflation, which countered the deflationary pressure caused by covid. Deflation is bad because it means that people are better off not spending money than spending, so they reduce spending, which causes recessions to get worse. Because money is now worth more than things, staff have their pay reduced in nominal terms or they are fired. Debts are measured in nominal terms, but money is worth more, so a bigger and bigger portion of peoples' income has to go to paying debts."
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md3gqk | What is Roko's Basilisk? Is knowing about it as dangerous as it is made out to be on the internet? | Technology | explainlikeimfive | {
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"The original Roko's Basilisk was a thought experiment posted by a user named Roko on the LessWrong forum. It used decision theory to postulate that an all-knowing, benevolent AI would inevitably end up torturing anyone with knowledge of the idea of the AI who didn't actively work to bring it into existence. The logic is that such an AI would want to start existing as soon as possible, so the fear of not working on it once you know it exists incentives as many people as possible to help create it faster. More broadly speaking, the term \"Roko's Basilisk\" can now be used to describe any knowledge that is inherently dangerous to the person holding it, for example a monster that supernaturally hunts down and kills anyone who learns of its existence. There's no evidence to suggest any such entities exist or ever will exist, so no the idea is not itself dangerous.",
"No it's not dangerous. The theory is a AI like sky net that becomes aware and powerful enough to bring itself into existence and take over the world would be able to extrapolate who helped and hindered its emergence and thus reward or punish people accordingly. Extended from that is that if you're are aware of this concept and don't actively help the basilisk come about you're stopping it and therefore dooming yourself",
"There's an old \"joke\" about a missionary and an Eskimo. It functions in the same way as Roko's Basilisk. > Eskimo: 'If I did not know about God and sin, would I go to hell?' > Priest: 'No, not if you did not know.' > Eskimo: 'Then why did you tell me?' > > -- [Annie Dillard]( URL_1 ) From the Eskimo's perspective, this is *dangerous* knowledge. His soul wouldn't be at risk of eternal damnation, if only he had never encountered any missionaries. Replace God with some inevitable post-singularity General Artificial Intelligence, and you can have the same situation. If you believe that such a GAI is inevitable (or even just plausible), that such a GAI would necessarily have some measure of self-interest and self-awareness, and that such a GAI can, in its own way, threaten you with something like eternal damnation (or tempt you with something like eternal reward, or both), then you *must* serve its interests. That's a lot to swallow. Is the Basilisk a dangerous idea? For most people, no. For a very select few, maybe. Then again, *any* idea could be dangerous, in the wrong hands or in the wrong mind. Another related idea is [Pascal's Wager]( URL_0 ). Pretty much, the Basilisk is simply the Wager applied to the Singularity rather than to some more traditional God. Refuting the Wager is the same as disarming the Basilisk.",
"It's not dangerous at all, it's entire premise is a logic fallacy. Just because someone had an idea doesn't make it an eventuality. The ide of Roko's Basilisk has to many confounding factors that would have to go exactly right in order for it to happen as presented, there are far too many situations that allow the narrative to skew away from that scenario, most notably the fact people think about it and similar scenarios constantly."
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md3te8 | How did the filming of the Apollo missions work? Was all lunar activity filmed? | How did filming the moon landings work? Was every event that took place on the Moon filmed, or was there some activity that took place off camera? | Technology | explainlikeimfive | {
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"There were cameras on the Moon missions, operated by the astronauts. There were also TV cameras, which had the big advantage that the recording was done here on Earth, where resources are plentiful. Landings were shot through the windows, relaunches were shot with TV cameras set up and left behind by the astronauts. Many events were filmed, but not \"all\" by any measure.",
"The landing was filmed on 16mm film, the film was developed when the astronauts returned. The first step on the moon was from a video camera attached to a landing leg, it was broadcast live and recorded on earth. Astronauts had a hand carried video camera that could be left on a tripod to video broadcast their activities. The camera on Apollo 12 was accidentally pointed at the sun and ceased to work early in the mission. One of the two astronauts typically carried a 35mm camera to take still high quality photos that were developed on their return. The rover, used only in the last few missions, had a built in video camera that could be controlled from Earth. This was the camera used to record the famous lift-off sequence of the LM from Apollo 17. The difficulty was that the commands sent, took over 2 seconds to reach the moon, so the controller had to anticipate the lift off and make a good guess as to how fast to pan upwards."
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md410f | Why does meth make people ugly? | Biology | explainlikeimfive | {
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"People on meth don’t eat. They imagine insects crawling all over their skin, they pick and pick and pick at their skin until sores develop. Meth inhibits the body’s ability to repair itself. Skin becomes loose and saggy. Meth mouth = poor oral hygiene, nasty rotten crumbling teeth. They often smoke. They crave sugary carbonated drinks. Throw it all together and you have one fantastic before and after pic.",
"It's a combination of things 1. Meth causes dehydration, that's what's responsible for \"meth mouth\". It's not because meth is caustic or whatever; not everyone smokes meth. Being dehydrated for long periods of time dries out the mouth and accelerates tooth decay. Failure to take care of dental hygiene can also play a part here. 2. It also causes appetite suppression which can lead to weight loss and a gaunt appearance. 3. Probably the most severe impact is sleep deprivation and long periods of being in a heightened stress state. This causes a ton of stress on the body which can contribute to aging. It can also cause paranoia, visual/auditory hallucinations, and drug induced psychosis in many users. That leads to behaviors like picking at skin obsessively which can create sores. And long-term high stress levels contributes to rapid aging in general (true for non-meth users too.) It's important to note not all these effects occur to the same degree in all users, and sometimes some of them can be mitigated by taking steps like drinking lots of water, regularly attending to hygiene, etc - and there's people out there who do. I've met \"healthy looking\" users, fat users etc. The ones who fit the stereotypes are some of the worst and therefore most obvious examples. It's still a terrible drug and is terrible for your brain and body, but I see a ton of misinformation even in this very thread about the side effects of meth and what actually causes them.",
"It makes people ugly because while they are using it causes them to forget about taking care of their bodies. After a month this way their bodies become destroyed.",
"as person who quit meth for a month any tips for my health ?"
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md4jwr | Teeth are not attached to the skull since they’re not bone but they still somehow remain with the skeleton and don’t fall off after death | Biology | explainlikeimfive | {
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"Teeth grow inside tooth sockets in the bone, they stay in those sockets after death because ligaments and dental tissue calcify",
"Teeth are attached to the skull. They are not fused to the skull. But then none of your bones are fused together. Your skeleton is connected by ligaments, not bone. When you die your ligaments dry out but keep your bones connected for awhile, eventually they turn to dust. Your teeth are also held to your skull by ligaments, the periodontal ligaments. And the roots of your teeth (which are part of the teeth) go into holes in your skull. So your teeth are held to your skull much more than the rest of your skeleton is held together. And your teeth will remain attached to your skull much longer than the rest of your skeleton will remain together.",
"One piece of the story that I haven't seen mentioned yet: mechanical retention. Tooth roots are rarely perfectly straight. In order for a tooth to come out it needs a path through the bone to do so. If the root is curved or flared, in essence it's mechanically locked in place the same way a dovetail joint holds wood together. True ELI5: Put your hand (tooth) in a bucket. Surround your hand and arm with plaster (bone) and let it set. Now try to take your hand out of the plaster. You can't because there isn't a pathway to pull your hand out due to the differences in shape and sizes of your arm, wrist, palm and fingers. Extra info: when getting a tooth removed, you might hear the dentist/surgeon talk about feeling \"pressure.\" We're literally expanding the bone around the tooth to make space so it has a pathway come out. Source: am dentist",
"I remember when j got to Navy boot camp, I had my four wisdom teeth pulled at once. It took sixteen numbing shots and local anesthesia to make it as painless as possible. I can’t remember whether it was the top or bottom teeth, but one side pulled out fairly easily while the other required splitting my teeth into quarters. The dentist said to prepare for snap, crackle and pop, which accurately describes how the teeth sounded as they were being jerked out. It took a few days to fully heal and socket rinsing with a syringe to clear out after meal food particles. Flushing them out and seeing the amount of food that got packed into the sockets were always a surprise."
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md5f0m | How Does A Tiny Multivitamin Capsule Provide 100% Daily Vitamin Needs For Almost All Our Body's Vitamin Requirements? | Biology | explainlikeimfive | {
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"Vitamins are a tiny, *tiny* percentage of our nutritional requirements. The amounts needed for health are usually measured in milligrams or micrograms. Easily fits into a capsule with room for binders and colorants. Most of what we need are macronutrients (\"macros\"): fats, carbohydrates, and proteins. Those take up a lot more space than the micronutrients you can (but mostly probably shouldn't) get from a pill. Think of it this way. If you artificially remove the micronutrients from food and eat ONLY fats, carbs and protein, you won't starve. You WILL start to have health problems related to vitamin or mineral deficiency (see: scurvy, rickets, anemia, goitre, pellagra, etc). If you eat no food and only drink water fortified with vitamins and minerals, you won't get scurvy. You'll starve to death instead. Macros are fuel for your muscles and brain. Vitamins and minerals are tiny specialised tools for health that can't be manufactured by human bodies for themselves."
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md69qc | The most powerful battleship of all time, the Japanese Musashi, could fire a shell the size of a car 27 miles. How did a moving ship like this accurately fire at another moving ship 27 miles away without modern day technology? | Other | explainlikeimfive | {
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"It didn't. Realistically, the extreme range could only be used for coastal bombardment to support an invasion. It also functioned as a standoff weapon. In thory, by having that long range capability, you'd keep the enemy away from your operational area. If enemy ships approach, they run the risk of getting hit which increases as they get closer. In practice American Battleships were better at this despite having a smaller range because they could detect the enemy sooner and had more accuracy due to their computerized fire control. Also, aircraft carriers fit this area denial role much better than any battleship, which further relegated battleships to coastal bombardment.",
"They had huge analog computers. Using cogs and wheels you are able to do the additions, multiplications and trigonometric functions required to calculate the trajectories of the shells and the movement of the ships.",
"\"Accurately\" is somewhat vague, particularly for extreme long ranges, and almost no battleship engagement was fought at long ranges. The longest recorded hit by a battleship on another is about 14.7 miles (26,000 yards) scored by the *Warspite* on *Giulio Cesare* and *Scharnhorst* on *Glorious* The extreme range of battleship guns was generally only used for shore bombardment where they'd sit off shore relatively stationary and lob high explosive shells at ground targets and spotters on the ground would let them know where the shells were hitting so they could adjust their fire. For ship on ship fights, they would use their range finders to guess the range to the target, estimate the speed, and then fire a couple guns ahead and beyond the target and a couple others behind and on the near side of the target. This let them get two separate trials in with the first volley and they would do trial and error until the spotters told them they were on target. In WW1 and much of WW2 ship fights took place within visual range, you had to have people seeing the shell splashes to be able to adjust your fire. Later in the war, the US in particular made heavy use of surface radar which could detect the shell splashes so they could adjust their fire from much longer ranges. At the Battle off Samar, the Yamato (Musashi's sister ship) didn't start firing until it was about 19 miles from the US forces, but really didn't start getting good hits until about 11 miles out. For the most part, battleship duals went on for a while because it was rather hard to actually hit the other guy. The *USS Washington* scored just 9 hits out of 27 shots with its main guns on the *Kirishima* at under 5 miles and that was considered really good even using its radar.",
"They used computers. No, really. Analog computers utilizing moving parts like a giant watch have existed for over a century. The first US Navy ship to use one is the battleship Texas, which is actually still around serving as a museum in Texas. These systems used gyroscopes to measure the pitch and roll of the ship, and used inputs from optical rangefinders and manually entered estimates of the targets direction to calculate the elevation and direction of the guns to properly lead the target. URL_1 URL_0 These systems, as described above, were generally accurate against moving targets out to a range of about 10,000 yards. Occasionally, ships would land hits further than that, but the odds of any shell hitting at that range was very low. Later systems were more sophisticated, and utilized radar to get even more accurate targeting info. Some, such as the systems on US battleships, could also detect the large splashes caused by missed shells. These systems could reliably hit ships out to about 20,000 yards and could work day or night, rain or shine. Beyond that point, you run into limitations resulting from time of flight and the limitations of unguided shells. You want an airplane or missile that can update its course as new information comes in, which is why aircraft carriers and missile armed cruisers/destroyers replaced the battleship. When the American Iowa class battleships were brought back into service in the 1980s, their analog computers were considered equal to or better than the best digital computers and were left in place. FYI, Musashi was 2nd ship in the Yamato class of two battleships. Both were built to largely identical designs. They had the same armament. Musashi had slightly better facilities for admirals and their staff"
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md6a4h | If radiation causes Cancer, How does radiation(Chemo) kill cancer? | Biology | explainlikeimfive | {
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"Well Billy I'm glad you asked. We first have to get rid of the concept that Radiation directly causes Cancer. What actually happens is that intense radiation can damage the DNA in cells which can lead to serious issues down the line, cancer included. Chemo as you called it doesn't use radiation. Radiation therapy however, uses the same principle of radiation leading to damage causing cancer but on a focused \"beam\" to try and spare as many healthy cells as possible and damage the cancerous cells instead. Edit: as u/Eona_Targaryen has said, what OP is referring to as Chemo is actually Radiation Therapy.",
"Since this is ELi5, your question is a bit like saying if water is necessary for life, how can someone drown. The same external force in different strength application can have radically different results.",
"Not a doctor but chemotherapy is not the same thing as radation therapy. Both are used to fight cancer.",
"Ionizing radiation can cause damage to living cells, cell mechanisms and DNA. That damage can eventually result in cancer. Killing cancer is just that, killing cells - the same mechanism that randomly damaged your healthy cell can now be used to target the cancer tissues and kill the cells you want to get rid of."
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md72kq | What is Panopticon? | Other | explainlikeimfive | {
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"\"Pan\" in Greek means \"all\" and \"optic\" in Greek means sight or vision. The term is used in two different ways. The first is a building design for a prison that has the prisoners in cells that are arranged in a ring around a central tower where the guards are, which allows for the guards to see everyone from that tower, and the prisoners to know that they are always being watched. The second is a society that is run on a similar idea of surveillance, where the government is always watching you. Some people feel that social media is an example of this."
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md7atf | why do our tummies grumble when we are hungry? | Biology | explainlikeimfive | {
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"I’ve heard that they make noises like that all the time, but, when our stomachs are emptier, it’s like the empty space in a guitar that lets you hear the sound. So an empty stomach is like an acoustic guitar, but a full stomach is like an electric without an amp."
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md8apz | If photons are massless, why is light limited to a finite speed? | Physics | explainlikeimfive | {
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"The exact \"why\" is kind of difficult to know. We don't have a good explanation for why the universe has a top speed or why it is what it is. We just know that it exists and approximately how fast it is. What we do know is that all massless particles have to travel at the speed of light through space. A massless particle can't travel any slower or any faster. But, and this might be a bit harder to understand, according to General Relativity, every particle in the universe is traveling at light speed through spacetime. That means that if you are at rest in space, you are traveling at light speed through time. Once you start traveling faster through space, you travel slower through time. At the extreme, massless particles like light don't experience time from their own perspective. If you could somehow hitch a ride on a particle of light, time would slow down to the point that it actually stopped and the moment you started moving would be the exact same moment that you arrived at your destination."
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md9ohb | Since black holes absorb all light, how were scientists able to take a photo of one? | Physics | explainlikeimfive | {
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"If you look at the photos, in the center you'll see a fuzzy black dot, surrounded by a ring of light. The black dot is the black hole, all light that goes into it is absorbed. The ring is light that just missed the black hole, so gravity bent the light that passed close by, but didn't suck it in, and so it escaped and was able to be picked up by our instruments.",
"Black holes produce no light, but the region immediately *around* the black hole tends to be extremely bright; all of the matter that's falling in towards the black hole heats up via friction, and emits a large amount of light that is visible across large distances."
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mdahkj | Why can't voice changed audio be reversed to reveal the original audio? | Technology | explainlikeimfive | {
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"Some changes are destructive, and leave no way to recover from them. Some have multiple plausible starting points. Eg, if I shift my voice's pitch up, how would you know? Maybe I actually shifted it down. If I do it well you have no idea what change to make to leave it as it was, unless I tell you.",
"It's not a reversible process because you don't know what the voice changer did. All you get is a waveform (the \"wiggling\" electric signal you feed to the speaker). That waveform is the sum of the original signal and the distortion signal that the changer introduced and you can't tell which is which. Simple example...I am playing a musical note. I run it through a simple frequency changer and you hear a tone of 440 Hz (the note A). What's my original note? You know exactly how a frequency changer works but you don't know what my original note was because you're missing two pieces of information, not one...you don't know my original note and you don't know what shift the frequency changer put in. Without knowing one of the two, you can't separate the signal from the distortion.",
"If I roll a pair of dice, I can't unroll them to get the original number unless I was tracking every aspect of their journey across the table with ridiculous precision. How fast were they spinning when they left the hand? How many times did they hit the table? How hard is the table they landed on? etc. When someone scrambles or distorts audio for the purpose of obfuscation, they are changing it using an element of randomness. Basically, every moment of audio has a different filter applied to it, and without knowing what each and every one of those filters is, it's impossible to properly undo."
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mdatel | why are we told never to lift with our backs meanwhile deadlifting is almost all back and seem to contradict safe lifting | Biology | explainlikeimfive | {
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"If you're deadlifting properly, almost all the force is supplied by your glutes and hamstrings (hamstrings in particular). Not your back. Sure, the back has to do work keeping the spine immobile and under tension, but you should not be pulling primarily with your back. if you feel a deadlift primarily in your back, you're doing it wrong.",
"When you deadlift you don't lift with your back, you lift with your legs and butt One of the most important parts of deadlift form is keeping your back straight, this puts the load in the arched spine rather than on the muscles of the mid and lower back. To get the bar up you're supposed to straighten your legs while pushing your butt forward, the shape of your back between your hips and your shoulders really shouldn't change during the process This is distinctly different from when people lift with their back by bending over and curving their back downwards, and then lift the object by straightening their spine back out to an upright postion. This requires a lot of work by the relatively weak muscles in the back instead of the massive glutes and quads",
"I think the more accurate statement is dont lift with your spine. Stand straight up, now bend over with your spine. Your hips should stay in place, but your back should now be curved. *that* is lifting with your back, which is bad because those muscles arent meant for lifting.",
"You never want to bend the lower back during a lift. When doing a deadlift, they only bend at the hips and knees, but keep the back, specifically the lower back, perfectly straight the whole time. Your lower back muscles are meant to hold you tight, not to do the lifting. The proper term is that you don't want to hinge at the back. You want to hinge at the hips. Try bending forward without bending your back. You don't need to go far enough to touch the ground. Do it while only bending at the hips. Keep your lower back straight and tight. You will have to essentially shove your butt backwards to do this. That's where you're actually supposed to bend during a lift. You then do the lift by squeezing your glutes and your legs to right yourself at the hips."
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mdb5k7 | Panama canal has gates because of the Gatun lake in the middle and the difference in the water level between Pacific and Atlantic ocean. How come there is a difference in the water level? And furthermore, how come there is no difference between Mediterranean and Red sea? | Earth Science | explainlikeimfive | {
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"The reason is the large difference in tidal ranges. On the Pacific side it can be up to 45 ft whilst on the Caribbean side it's only 3 ft. Without locks this would create a huge tidal bore making the canal impassable. URL_0"
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mdb9mb | Why is it that blood rushes to your head so quickly when you’re upside down, but blood doesn’t pool in your feet when you’re standing? | Biology | explainlikeimfive | {
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"Our bodies are designed to handle gravity pulling blood to our feet. The veins in our legs which transport blood upwards towards the heart have little valves in them, so blood can only flow upwards through them. We don't have as many valves in the veins in our neck, because normally gravity pulls blood the way we want it to go.",
"It's not the blood you're feeling, it's the blood pressure. As stated by someone else, your body is designed to carry blood as you stand or lay down. Upside down pushes the weight of the blood above you towards gravity. This applies pressure to your head, a very delicate nervous system with closely knit receptors that even a small amount of incresed pressure can result in an alarm to your brain in the form of pain."
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mdbc4j | Dentists always advise to floss or use interdental brushes (in addition to brushing, of course), but no one recommends mouthwash. Does mouthwash make a visible difference? | Biology | explainlikeimfive | {
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"I'm a registered dental hygienist. There's different mouthwash for different needs. There's fluoride mouthwash, which gives you am extra bit of cavity protection. There's anti-gingivitis mouthwash, which helps to kill even more germs in your mouth than brushing and flossing alone. There's even whitening mouthwash, which are typically peroxide based. When my patients ask me which brand is best, I tell them that the brand usually doesn't matter. You look for what the mouthwash is doing for you (for example, after rinsing with a fluoride mouthwash, avoid eating and drinking for a half hour afterwards). Do I recommend mouthwash to everyone? No. Only if I feel it could benefit them and their particular needs. And yeah, they make your breath fresh too! But cleaning your tongue thoroughly will help with that too (use a tongue scraper!) Edit: Thanks so much for the award! Much appreciated :) Edit2: Thank you guys for the awards! ❤ I'm happy to help Edit3: Wow, it's been a fun night! Thanks again for all the awards and for all your questions, but I have to head to bed! Please don't forget to visit your hygienist every 6 months for a cleaning and checkup! Don't be afraid to ask them questions, that's what we're here for! And feel free to peruse my previous answers, I've answered a ton!",
"How bacteria works in your mouth EL5: by itself bacteria floating around is not nearly strong enough to get through your enamel (hardest outer layer of tooth). But when bacteria is left around long enough they begin to stick together to form a biofilm. Now this starts as a soft biofilm called plaque, if you were to brush your teeth or scrape it with your finger nail you would be able to remove this soft biofilm (plaque) without much effort. However after about 24 hours that soft plaque begins to strengthen and harden into tarter. Now tarter is solid, no matter how hard you brush, it’s not coming off. That’s why you go to the dentist, they need to scrape the tarter off. Think about the bottom of a big boat, the longer it’s in the water the more grimy the bottom gets, if it’s in the water for long enough barnacles will begin to form. No matter how fast you go through the water the barnacles will never come off, You have to scrape these barnacles off. Mouthwash is the equivalent of trying to go really fast in your boat to wash off the barnacles, it’s not going to do anything but maybe polish up the top layer of barnacle but at the end of the day there are still massive barnacles on your boat.",
"It's like soaking a pan vs using a sponge. A soak helps, but it doesn't get everything, And if you're using a sponge you don't really need the soak, but it can be nice to use both",
"My dentist told me to stop using mouthwash after brushing, apparently it washes away the good stuff in toothpaste. She did say it was fine to use as a freshen up in between brushes though.",
"My dentist recommends mouthwash, but the purple Listerine full oral care stuff, not your generic mint mouthwash. Supposedly, it helps to remove/kill plaque and bacteria and such from hard-to-reach places, to help protect your teeth and gums, in addition to freshening your breath.",
"Brushing and flossing mechanically cleans away the plaque from your teeth, which prevents it from turning into biofilm and eventually decalcifying your enamel (i.e. create a 'cavity'). FLUORIDE-containing mouthwash can help remineralize the ename on your teeth, but it won't physically scrape the bacteria away.",
"dentist here and the reason most of us recommend it is pretty simple. if you have inflammation that does not get better with brushing we tell you to use mouth wash, or if you have a lot of cavities so we can stop their progress. their use is it pretty much limited to select cases where normal methods are not enough on their own so we need additional help. ps: don't use mouthwash every day cause they can stain your teeth a good rule would be daily use for a week and 2-3 weeks without them additional info: there are also stronger mouthwashes that need prescription (such as anti-biotic, or pain killing mouth wash but these are really given to super specific patients such as patients who have cancer and receiving chemo).",
"There are several different kinds of mouthwash. Some is just for a temporary anti-bacterial effect, some has fluoride, and some is for dry mouth. The first kind is basically better than nothing, but not as effective as brushing your teeth. The second kind can help if you have soft spots that need to be re-mineralized, but for the general public the fluoride in your toothpaste and water is sufficient. Dry mouth only affects some people. None of them are as effective as flossing in terms of reducing inflammation and gum loss. So basically, a dentist might recommend a mouthwash if you have a particular issue, but for the general public emphasizing brushing and flossing is much more effective.",
"Side note: I used to get tonsillitis 4-6 times / year. I had to be transported by ambulance once because my airway closed completely. EVERYONE said I needed to get them out, but I also heard horror stories about how bad the recovery was. I started gargling with listerine or other alcohol-based mouthwashes and haven’t had tonsillitis in almost 10 years.",
"my teeth were getting really sensitive to cold/cool water for years. i was brushing(softly) with Sensodyne toothpaste and flossing a half dozen times a day, but it wasn’t getting better. then I bought some fluoride mouthwash and within 48 hrs the problem was basically solved. I can’t believe I overlooked something so simple for so long! absolutely ridiculous",
"My dentist suggested that I use a mixture of mouthwash and hot water in a water pik and it has worked very well for me.",
"Mouthwash kills bacteria, but they can grow back if they have an environment. Brushing and flossing take away that environment in the first place.",
"Not really. Most mouthwashes contain alcohol, which can have the effect of making breath smell worse. Additionally, though this isn’t related to oral health, studies have shown that there are nitrate-reducing bacteria in the mouth, and when these are killed off it reduces nitric oxide bioavailability and decreases the blood-pressure lowering effects of exercise.",
"Dentist here. You will get varying opinions. the evidence that non fluoride OTC mouth wash does anything is.. meh. Fluoride mouthwash has solid evidence but in my experience is rarely used properly and can sometimes be harmful if used wrong so I don't usually recommend it. There is an OTC mouth rinse ingredient that is slipping my mind right now that has a positive impact on gum health and I'm too lazy to look it up. Everyone is different but if most people spent the time they use rinsing with just brushing and flossing more meticulously they'd be better off. There is a good chance another dentist will disagree with me on this and that's just how medical treatments are. There's always exceptions",
"What’s interdental brushes and waterpiks? Sorry I’m uneducated I only know about flossing and mouthwash",
"Brushing and flossing are both physical, mechanical means of cleaning your teeth. Bacterial plaques (growth colonies) are sticky and love to stick onto and hide in between your teeth and on/under the gum line. If you only use mouthwash, not floss, you will have food buildup and bacterial plaque buildup between your teeth, which could eventually harden into tartar which is much harder to remove. Additionally, those bacterial plaques are creating acids that are slowly etching away at your teeth. AHH! Yes, every day bacteria starts to build up that will rot your teeth if you don’t brush and floss the plaques away. Your body has natural minerals and compounds in your saliva that remineralize your teeth to a certain degree, but the trick is the bacteria cannot be allowed to build up too much, or the acidifying effect will outweigh the remineralizing effect, and your teeth will start to be etched then cavitated and rotted without any treatment. Bonus points: The main mineral in our saliva that remineralizes our teeth is hydroxyapatite. When we brush with fluoride toothpaste and properly wash with fluoride mouthwash (no eating or drinking for 30 mins after!) , we add fluorine to the mix, and a new mineral called fluoroapatite binds to our teeth. This mineral is much stronger and more resistant to the acid attacks by bacteria, giving us a better fighting chance at a healthy mouth! One last thing, it’s possible that mineral deficiencies or other disorders could cause poor dental health. It’s a good idea to ensure you have enough calcium in your diet for strong teeth and strong bones [doot doot!]",
"Most mouthwashes do very little. Most are like putting perfume on instead of showering and rubbing your dirty body with a washcloth. They definitely do not clean between teeth.",
"The best way to clean your tongue that I found is if you put baking soda on your toothbrush and then scrape your tongue forward. The baking soda really cleaned the tongue amazingly well better than a tongue scraper. Give it a try and you'll see the results immediately.",
"Mine told me to mouthwash before tooth brushing as there’s less fluoride in mouthwash than toothpaste. So mouth washing post toothbrush is in effect washing the fluoride off therefore lessening the effect of your toothpaste.",
"I have no data on this, but lately there has been a lot of interest in the bacteria that normally live in and on our bodies; the \"microbiome\". Things like antibiotics seriously mess with th microbiome, sometimes in harmful ways. Sometimes you have to take antibiotics but it is not without cost. Mouthwash, like antibacterial soap, and antibiotics is likely going to kill masses of good and bad bacteria in your mouth, maybe it would be bad to do that. It *may* not be harmless. I stopped using it a few years ago for that reason.",
"My dad and everyone on his side of the family are dentists (i am not). My dad has always said that mouth wash gives nice breath but it does nothing for your dental health and that it is all advertising. Whereas flossing is important for both your teeth and gum health.",
"JUST FYI: This is a fact most people don’t know about. Most mouthwashes are acidic on the pH scale. Some even akin to soda. I’ve found the least acidic mouthwash to be Act total care I believe and that’s still a pH of 6. I would recommend using a pH balanced mouthwash.",
"mouthwash is fine but think of it this way. when you wash your car do you just spray it with water?",
"I feel like both normies and dental hygienists in this thread don't understand the true use for mouth wash. Yeah killing germs is great, and that's what makes it different than just water. But it's the hard swishing you do with it, that and food that is still lodged in between teeth that may have been loosened but not released can be dislodged. You can totally do this with water, but the germ killing bonus and minty freshness is a bonus.",
"Dentist here. Mouth wash is unnecessary no reason to use from a preventative standpoint as long as brushing and flossing are done well. Toothpaste is also unnecessary, but it helps-mainly because of flouride, and it’s ability to get incorporated into the tooth making it more resistant to acid. I know a number of dentists that don’t use toothpaste. The goal of brushing and flossing is to remove and disrupt biofilm and plaque which lead to caries and inflammation. Toothpaste is unnecessary to accomplish this.",
"Using a pre brushing mouth wash that helps to break down biofilm is much more effective than traditional mouthwash which mostly just makes your mouth feel tingly.",
"My last dentist always used to say to use it, but my current one doesn't which is nice because I've never liked it or used it on a regular basis.",
"i am under the assumption that flouride is important during the early stages of tooth development so since we dont have flouride in our drinking water, i have my kids use non-alcoholic flouride mouth wash.",
"When I was a student in pharmacy school, we did an experiment in which we rinsed our mouths out with mouthwash multiple times then took swab cultures from our mouths and plated them. Within less than an hour there was no discernible effect from the mouthwash. You can get fluoride from toothpaste, and I don't think anybody has ever published evidence of a clinical benefit from mouthwash, it's all marketing hype.",
"Alcohol based mouthwashes are associated with oral cancer. They cause DNA damage that result in malignant propagation. This is why heavy alcohol drinkers are associated with increased oral cancer. The mouth has natural bacteria that resides and they play role for good oral hygiene. While there are numerous different types of mouthwashes with variety of use, the alcohol based ones (think listerine) should only be used sparingly. It should be noted that in fact the Listerine drummed up halitosis as a disease to [sell more mouthwashes]( URL_0 )",
"Dentist here. The biggest difference between the benefits of those habits has to do with the idea of plaque as a biofilm. Bacterial cells by their lonesome are easy to \"flush\" out with things like mouthwash or salt water. However if they hang around long enough they will get together with friends to form a colony which gets more and more organized over time. They start secreting materials that form roads and tunnels for nutrient transport, and many protective outer layers to ward off invaders and prevent themselves from washing away. Under a microscope the level of organization and complexity would blow your mind. On the outside it looks like what we would call plaque, but microbiologist call it specialized biofilm. Washing away with just fluid will no longer work, you gotta mechanically debride them away, which is what brushing/flossing/proxy brushes do. However after they've been mechanically disturbed away, a mouth rinse can do wonders at killing the remaining bacterial cells so that it takes much longer for new colonies to reach critical mass to start the biofilm formation. Tl;dr brushing makes plaque go away, mouthrinse is pretty good at preventing it from forming in the first place. Both are important and neither alone is perfect"
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mdbnbg | If we know what chemicals make us happy and how, why cant we create a food or something that keeps us in a good mood permenantly without ruining our dopamine receptors? | Chemistry | explainlikeimfive | {
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"We are only just scratching the surface in our understanding of how the brain works. We have seen that activating the dopamine and serotonin receptors tends to make people happy. But, there is an ocean-sized gap between that basic understanding and making a drug that will always make people happy with no side effects. It's entirely possible that the human brain simply isn't capable of maintaining a permanently happy mood without long-term damage. It might be like trying to run a car at top-speed all the time and not expect the engine to break down.",
"We already have, kinda- cocaine and MDMA both work pretty directly on our brain chemistry. The problem is that, given the choice between being a productive member of society or being automatically happy all day, most folks will choose the latter. For that reason, societies tend to quickly outlaw those types of chemicals",
"Happiness cannot be mantained, happiness is a change not a mood. A broke person can get very happy if you give them a new car but Elon Musk won't becouse it doesn't mean a change to his situation.",
"One of the main reasons is that being unhappy is what drives us to do things. We get hungry so we eat, we feel lonely so we seek company and build a support network, we feel bored or unaccomplished so we actually do something with our lives. While none of these are \"good,\" to feel, without them we would probably never leave the chair we are sitting in right now. This is why drugs like Opiates are so dangerous. Even ignoring the physically addictive effects, they make life not worth \"living,\" because the needle is so much better than actually doing something. Also, a more medical reason is that our brain will always try to maintain homeostasis. It's why even the happiest thing to ever happen to us will fade and we will need something else to drive us. It's pretty much impossible to feel anything without our brain desensitizing itself to it over time."
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mdc4mv | what are the various ways a star "dies" and what are the factors that determine which happens? | Physics | explainlikeimfive | {
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"TLDR: How big and massive they are determines how long they last and what happens when they die. The bigger the star, the shorter its life and the more spectacular their demise. Stars are a constant balance between the gravity of all that mass trying to crush it inwards and the outward pressure created in its core by the fusion of atoms and the associated release of energy. As a star becomes less energetic gravity crushes it inward, while a more energetic star pushes outward growing in size. For most of its life a star will fuse Hydrogen into Helium which is a stable and a relatively slow process. As the Hydrogen runs out stars will start to collapse inward which will start fusion of heavier elements like Helium, Carbon, Oxygen, and Nitrogen, and then eventually up to Iron. Once a star reaches Iron fusion it's dead. The creation of Iron is a critical moment for stellar fusion because Iron is the first element made in a star that doesn't release energy when it fuses, instead it needs additional energy put into the reaction. So Iron is a fusion poison, as it builds up the fusion in the core stops and gravity takes over. The smallest stars will never reach this stage, they will burn hydrogen and helium for all of their lives and due to the dynamics of their atmospheres gas will undergo convection in and out of the core and into the atmosphere so more fuel is always pumped into the core. That's why the smallest stars last the longest, they are able to burn all of their fuel. Eventually these stars will blow out their out atmospheres and become white dwarfs, stars that are basically cinders. Larger stars don't have convection so their cores will burn out more quickly. They will burn up to Iron, and when they do... they explode. This is what we call a supernova. It takes millions of years for a star to burn it's hydrogen, but every element heavier than Iron is made in a split second during the supernova explosion. The largest stars have so much gravity that their cores will collapse down into solid material with no space between the atoms. These are neutron stars where all Protons and electrons are compressed into a solid Neutron mass. What holds these stars up against the force of gravity is Neutron degeneracy pressure, the neutrons themselves resisting being crushed together because there isn't enough space. These stars are incredible dense and hot, and spin very fast. Even heavier than that will cause the core to collapse even further, down to a single point. A Black Hole."
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mdc731 | -Why is removing the filibuster so important for democrats? | Other | explainlikeimfive | {
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"It is not so important for just Democrats. It is just that right now they are in power of the Executive (Biden) and the Legislature (both houses controlled by Dems). So that means the only “power” the Repubs have against being steamrolled by Dems is the filibuster. When the other party gets in charge they will say the same thing. I am Dem but I agree that completely eliminating the filibuster is not a smart idea because if the Senate swings back to Repubs, they are going to rue the day if/when they do remove the filibuster. Its a game, every time the majority swings, to be plain about it, this dance happens",
"It could allow them to do things without any Republican support. Alas, they might not always be the majority, and if they ever lose, the new winner isn't going to want to restore the procedure until they have repealed every law that they passed. By requiring 60 Senators agree on something, it is harder to get things done, but it's also harder to undo things. In general, it's an important safety feature, and turning it off is more likely than not going to cause more trouble than it solves."
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mdd65v | How is calibration equipment...calibrated? | Technology | explainlikeimfive | {
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"Using \"standards\" - there exist objects that represent units of measure, ounces, grams, cm, inches. For chemical analysis there are also standards but those are usually just pure samples of whatever they're measuring.",
"There are levels of calibration, and you just need upper level. Think as you have a steel meter take it as lvl 1. So the calibration equipment is lvl 2, their calibration equipment is lvl 3... And this goes up to the definition of meter.",
"What type of calibration are you wondering about? Generally there's time-intensive ways to make something of that's highly calibrated, like [surface plates]( URL_0 ). But once you've gone through the effort of doing that you can use your new calibration thing to test other things. And nowadays much of the precise calibration is done with physics and lasers and stuff. Not practical to take to every thing that needs calibrated, but if you make one really good thing it can check a lot of other things."
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mddlok | Why there is no negative mass? | ELI5 why there is no negative mass in our universe unlike charge | Physics | explainlikeimfive | {
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"We don't know. There just isn't. Mathematically there is no reason why it can't exist, but we can't say why it doesn't."
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mddoob | How exactly do bears go back to normal after being sprayed with bear spray? | Once sprayed, would the bear have to find it's way blindly to a water source to wash it out? If it's in its eyes and nose, would the bear even be able to navigate? Is the bear doomed? | Biology | explainlikeimfive | {
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"The bear has tears and mucus membranes in its nose that will flush out the stuff after it cries for a while.",
"No, the effect doesn't last forever. Almost like pepper spray on humans. It goes away with tears, evaporates. It lasts what, about half an hour before it is just a mildly annoying.",
"Bear spray is like pepper spray. It’s an irritant meant to distract/stun and cause temporary harm- not permanent damage."
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mdduzw | Why does an old necklace, (silver in appearance) start turning a yellowish gold color? | Chemistry | explainlikeimfive | {
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"Tarnish. Most silver isn’t 100% pure silver, it’s a very soft metal, so to help keep damage from happening most things are a silver alloy. For example, one of the most common kinda of silver is “sterling silver” which is about 90% silver and 10% copper or another metal. Those other metals can tarnish and change the color of the metal, like how iron rusts red, or copper will tarnish green, the mix of metals will give the tarnished silver a darker/yellow-y color."
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mde1sn | If processed sugar is that bad for our bodies, why do we gravitate towards it so much? | Biology | explainlikeimfive | {
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"It’s not that it’s inherently bad, it’s just that sugar is an extremely good source for energy and evolutionary having a sweet tongue was pretty helpful in indicating foods with high caloric value. We live in a part of world and time now in which lack of sugar is not a problem anymore - we have more than enough. But we still have that sweet tongue.",
"Go back 10,000 years. Sugar was a rare treat for humans and is honestly beneficial for the energy it can provide. If you can get honey without getting stung by a bee, it's worth it. Fast forward to today. We found where the sugar is and we're farming it. That was not intended by nature. High blood sugar can kill you, and the protection mechanisms in the body don't work properly when under constant use. Humans are not meant to have sugar constantly, but the reward for getting it (it tastes good) remains.",
"Its basically gold as far as our body is concerned. Its pure energy in the easiest form to extract for our bodies. Energy that used to be far more rare in nature, but modern agricultural practices have made it incredibly common. Too common in fact. For billions of years the fear of our ancestors was not getting enough energy to survive and reproduce. We have evolved to stockpile it as fat whenever it is common to prepare for times of it being less common, but nowadays for many people these less common times never come around."
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mdes88 | Is there a specific reason/influence that there was such a wide variety and popularity of tobacco/alcohol shaped candy for kids (bubblegum cigars, candy cigarettes, gummy beer bottles, chewy bottle caps)? | Other | explainlikeimfive | {
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"Not an expert but not long ago it was normal for everybody to smoke and drink. It was what Grownups did so kids started searching for something that made them feel just as mature. Somebody saw a way to make money out of that. People try to make money from everything and kids are an easy target group cause they don’t care about background Info and consequences."
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mdexcd | How is a screw that is screwed into a wall able to hold so much weight no matter the size of the screw? | Physics | explainlikeimfive | {
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"Screws are generally iron or steel. A very very very strong material, especially compared to the wood/plaster/drywall the rest of the house is made out of. Which is why when someone in a house breaks or snaps, you’ll see that it’s the other material that breaks, while the screw stays in one piece.",
"Screws are designed to hold 2 forces. The force along the sitting force that pins the objet to the (ususally) flat surface under. This is why you need to turn the screw many times as the treaded part is doing this job. The shear force that keep the object from sliding sideways or cutting the screw. That is held by the cylindrical part that would be if the treads were cut off."
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mdf7e3 | Why is it offensive to ask how much someone makes? | Other | explainlikeimfive | {
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"In some social circles, how much you make is an indication of your worth as a human being (I'm not saying that's right -- it's just how some people think). The more you make, the more \"worthy\" you are. It may be considered rude to ask, therefore, because you may make someone feel bad. By the same token, you may end up feeling bad yourself, when you find out that \"unworthy\" person actually makes twice what you do.",
"Honestly it really isn't, it's that companies don't want you to figure out you're being underpaid for the same amount of work. That rule is so that they can pay as little as they can without you asking for a raise.",
"Once you start making money you'll get it. But one thing that makes it rude is the suggestion that someone can't afford something. In that they look poor. It can go in the other direction as in one looks like they make enough money to buy something for the asker. In general it's private information because it labels you in a certain class and that's not really a good thing to be direct about. However there should be more discussion of wages between workers. Because the sense of privacy works against the ability to argue for fair wages. But that should be navigated with caution.",
"In my experience, when two (or more) people disclose their respective salaries to each other, the person who makes less always feels bad about it — in a “my life has been a series of mistakes” kind of way. So I find it best to not ask, nor tell.",
"It’s not offensive, it’s artificial conditioning. In the past decade, my income has fluctuated between 24k and 70k. I have a doctorate and I’m fighting against Masters level and even Bachelors level for positions. That’s just the way the world works. When I am looking at salaries, it’s going to piss me off if I find out someone with a lower degree is making as much as me with the same experience and output. Looking at it from a more general perspective, if a woman finds out a man makes more than her for the exact same job or if an LGBT individual finds out they’re making less than their vanilla counterparts, obviously questions will be raised. Income is really just a number, but if that number is different for people based on anything other than productivity or education, it’s a major issue. There is nothing offensive about discussing wages aside from the employer selectively choosing wages outside those metrics.",
"Personally, if someone asks how much I make, I feel like they are judging me based on my answer. Also, why would they want to know? Are they going to ask for money next :p",
"1. Companies don't like it when employees talk to each other about wages for a number of reasons. It could open up litigation (why is person A paid more than person B for doing the same job and with the same level of performance?). It could cause employees to want raises (Person A makes this much, I want to make that much too!). There are probably more reasons, but ultimately companies want to save money and therefore encourage the mentality of people not discussing their wages with others. 2. It can paint a person's image a certain way in the eyes of others. If Person A who makes $30k a year knows that Person B makes $130k a year, Person A could feel jealous of Person B, could belittle their feelings of stress, and ultimately it could affect of number of interactions negatively due to class appropriation. Since wealth is not only determined by income but also by debt, it's an incomplete part of the puzzle and could therefore be class misappropriation, but with all of the negative interaction elements mentioned earlier. 3. Put yourself in the shoes of Person B for a second - Person A asks you how much you make a year. You make $100/year and your debts are paid, but you feel that maybe Person A makes less, maybe a lot less. Statistics show that those lower on the socioeconomic scale have a higher likelihood of commiting crimes. What if when Person A finds out you have $100k/yr, this leads to either Person A or someone Person A knows robbing your house? Now, I should quickly say that this is judging poor people to be criminals and it's not right to do so, but it happens kind of often and is a reason for those who make more money to hide how much they make from those who are poorer than them. 4. Let's say Person B is bragging about how much money they have because they've never felt so rich before. They just got a promotion and got their first Christmas bonus. They now make $50k a year and they're bonus check was $2k! They're ecstatic. Person A could have reasons for not wanting to disclose their salary. Maybe Person A makes more and doesn't want to accidentally kill their friend's mood. Maybe Person A makes less and doesn't want to risk Person B making Person A feel poor. TL;DR - there are a number of reasons for people not wanting to talk about wealth, someore situational than others, but overall it's just become a general rule so that we don't see each other in generalities based on income level without seeing the full picture. Also, I think I have social anxiety, so maybe not everyone can relate to these.",
"It depends on how your wages are paid. Most public sector workers, some unionized workers and some workers at large corporations are paid wages strictly based on their position. If you have a certain title, there is a known amount of wages that go along with that title. So someone asking about your wages is really just exercising curiosity about your industry or workplace. If you receive competitive wages - such as with most private sector professional work - asking about someone's income is a proxy for asking about their social status and is almost always a precursor to attempt to judge them based on that social status. As a result, it's considered offensive.",
"I don't call it offensive, I call it inappropriate. There's a multitude of reasons why someone would want to keep that private. Sometimes at work it could and certainly would cause issues between colleagues if someone discovers that his friend, with same experience, is getting paid more, for example. Sometimes people wanna conceal that info to give the impression that they are making less money. So they don't want to reveal that they make more than people expect them to. Sometimes it could indicate something wrong is going on for example. Say a guy that has an expensive sport car reveals he's only making 1000$ a month for example. How would that add up?! What sort of eyes and ears would that pop?! What illegal shit is this guy doing?! Etc... I can literally keep giving examples till tomorrow. So while it's not offensive in any way, it's definitely not so appropriate.",
"With your co-workers...afaic, talk about it. As said already, the company doesn’t like it because it can....lead to problems. I feel it’s about protecting their own interests. In social circles...it’s really no ones business.",
"A lot of people set their owners self worth on what they make. A lot of people judge others based on what they make. Given those two things, it's automatically an intimate detail you don't share with people you're not intimate with. It requires a huge amount of trust to discuss it.",
"The only answer, as some others have stated, is that companies have spun it to be so. They want you to feel weird asking others about their salary, or telling others yours. They want to be able to pay person a $x and person b $y for the same job and have no one the wiser. Think about it. Most people are more willing to tell you about what they did to their SO in the bedroom (or whatever room) last night than they are to tell you their salary. Personally I actively encourage anyone who will listen to be open about their salary. Its one of the few powers we have over our corporate leaders (in America at least.)",
"Sometimes I ask it when people are really obnoxious about how much money the gubberment takes for taxes because the US tax brackets are pretty low compared to other countries for all brackets. But like not when they are complaining where their tax dollars are going but like I think a significant amount of Americans have no idea how their taxes are calculated even though they literally have to file them every year. The worst was when Bernie Sanders was running as a serious contender and all these conservatives were spreading rumors about wild amounts of taxation over healthcare. I think James Woods or someone said you’d suddenly be taxed 50% of your income if you made over $30k a year which is absolutely absurd. (Although if you were paying cancer bills in the current healthcare system the same hypothetical year an increase to 50% might be cheaper comparatively to your medical bill which also isn’t okay) Anyway as others said it feels bad when people ask you about your salary because it also leads them to maybe judge how you spend it as well. My sister has always made more money than me but when she briefly made like 28k a year to judge when I was only making 28k a year and got into some debt she was like “I still made money and had no debt.” Maybe so but it’s not easy and cost of living where I live is much higher and you never know what’s going on in someone’s life to judge. Also I make 65k a year and I’ve found that the best way to get out of debt and have savings is to simply make more money. My life is still the same but with significantly less financial stress and anxiety. I feel like there’s a major case to be made that so many low wage people don’t get paid enough instead of portraying them as irresponsible because they have debt."
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mdfku6 | What is the P versus NP problem? | Mathematics | explainlikeimfive | {
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"So we have problems that can be solved, for example, 15x=75, and we have methods to solve them, in our example we have algebra that tells us x=5 easily. We call these P time problems. Some other kinds of problems aren't so simple, like solving prime factors. What's the prime factorization of 3640? It's really hard to do that without checking every available combination. We call these harder problems NP time problems. The last thing is that we can sometimes find that an NP problem is actually a P problem, we just didn't know the easy solution. A recent example is that we found a P solution to determining if a given number is prime. The P vs NP problem is this. \"Can all NP time problems be collapsed into P time problems?\" This is difficult because as it turns out, the P vs NP problem is itself an NP problem, which is a weirdly provable statement.",
"Computer scientists like to categorise problems based on how quickly they can be solved. P is the set of problems that can be solved quickly. NP is the set of problems that can't be solved quickly, but a correct solution can be recognised quickly. For example, if given a completed Sudoku puzzle it's very easy to check its correctness. It's much more difficult to find the solution in the first place. Sudoku is an NP problem. The million dollar question (literally, there's a million dollar prize for the first correct proof) is: Are all NP problems actually P problems? That is, if you can quickly recognise a solution to a problem, does that mean you can also quickly find a solution?"
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mdg4wd | Why do humans feel safer in closed environments than in open ones? | Biology | explainlikeimfive | {
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"In a closed environment there are only so many directions a potential threat can come from. An open environment, especially a poorly lit one you can even start to imagine threats because there are many times more possible ways to harm you"
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mdh19g | why Gödel’s Incompleteness Theorems is very important in mathematics and philosophy? I’ve been reading but I somehow can’t absorb the technical stuff | Mathematics | explainlikeimfive | {
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"Incompleteness shows that there will always be true, but unprovable statements for any axiomatic system you have. That's important because mathematics and philosophy are axiomatic systems. This gets rid of any hope of \"100%ing math\", and also introduces proof of unprovability. My favorite example is that if you can prove that the Rieman Hypothesis is unprovable, then it has to be true, because any counterexample has to be provable.",
"He basically blew up the idea that we could ever know everything. There are statements that we can prove are true, and there are statements we can prove are false. Then there are statements that we’re not sure about. For a really long time, people thought that we’d eventually figure out how to deal with all the ones we’re not sure about...once we found the right tools or formulations or whatever, we’d be able to prove if they were false or true. Godel proved that any system of making statements (math, philosophy, etc.) that makes rigorous true or false claims will *always* contain statements that you can prove cannot be determine to be true or false. It’s not a problem of finding the right tools, he proved such tools cannot exist. This was a significant bummer to a lot of mathematicians and philosophers who’d spent entire careers trying to develop those tools.",
"Godel's incompleteness work is important because it imposes some fundamental limits on the 'laws of reasoning', almost in the same way that the speed of light is a limit in the laws of physics. Incompleteness means that we will never be able to write a computer program that can prove \\*every\\* theorem of logic, but will never accidentally 'prove' a falsehood, for instance."
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mdhay4 | The Green Lumber Fallacy | I ran into it on Wikipedia, and I can't for the life of me understand it. Halp. | Other | explainlikeimfive | {
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"It’s basically the idea that what looks like important knowledge about something may not be important to doing it well, and what looks unimportant might actually be really important. The name comes from a story about a guy who was very successful trading (making investments) in “green lumber”. He was objectively good at it, he makes lots of successful trades over a long period of time. It turns out he thinks that “green lumber” is wood that is literally the color green. It’s actually lumber-speak for “freshly cut” and it’s brown like any other wood. This guy was incredibly ignorant about something as basic as the substance he was actually trading. *But that didn’t matter because it wasn’t important to what he was doing.* You do not need to be an expert on everything about a subject to be good at it...you only need to be an expert in those things that matter for how good you are.",
"This explains a lot of modern life. Imaging a publicly traded company, let's call it \"WorkGo\" (NYSE: GAYM) and a number of incredibly intelligent people realize that the the stock is about to experience a \"short squeeze\" - the term is irrelevant, just know that it takes a LOT of skill to identify such a stock and to understand what to do about it. So that person invests. Then imagine five million other people hearing about this cool new idea of investing in such companies because \"buy low, sell high\". They have no clue what a \"short squeeze\" is. Now imagine the \"Wall Street Insider\" experts dudes who short sold this stock looking around knowing that the tens of millions of people are getting rich despite their ignorance of how the whole thing works."
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mdiolw | Why do we feel like we are freezing cold when our body has a fever of over 100 F? | Biology | explainlikeimfive | {
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"Your body has a set point temperature that it wants to be at. Normally this is around 98.6 F. The way that your body causes a fever is by moving this set point up. So, what used to feel just fine is now cold because the temperature that your body wants to be at is higher than before. Your body reacts by shivering and encouraging you to seek warmth, hence the fever.",
"I think I could add a slightly more direct answer that what you *feel* is not the temperature. E.g., a metal fork feels colder than a napkin, but they're both actually the same temperature (room temperature). Feeling cold/hot is actually a sensation of temperature *exchange,* plus expectation. Metal feels colder than a napkin because the metal greedily absorbs your excess body heat, and the napkin is slower (i.e., metals are great heat conductors). Maintaining a higher temperature than normal takes more work, too, so the body has to do something to heat up. Shivering helps with that. The sensation from shivers and the difference in where your brain *wants* your temperature versus where it actually is = you having the sensation of coldness. Finally, once you're at a higher temperature, that means the air *feels* colder relative to you. Larger temperature differences = faster heat flow, which feels colder. Just like when the wind picks up, the air is the same temperature, but the rate of heat flow out of your body is higher, and that feels colder."
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mdixl6 | Why do US citizens pay taxes in a different way? | Economics | explainlikeimfive | {
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"We pay a federal income tax that comes directly out of our paychecks. At the end of the year, we have to calculate exactly how much we were supposed to pay according to the current year's tax rate brackets, deduction/credit schedules, etc. If we under-paid, we owe the difference; if we over-paid, we get a refund. Aside from that, we pay state & local sales taxes when we purchase goods and services. Additionally, we pay property taxes if when own real estate (including our primary home). Out of curiosity, how is this different than what you are accustomed to?"
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mdj222 | I am not able to understand what causes this ? how this happens How 6 people suddenly turn into 5 guys in front of my eyes... | Other | explainlikeimfive | {
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"Notice how in the first configuration there is a face completely above the cut and one completely bellow the cut. And in the second configuration there is a rectangle completely above the cut and one completely bellow the cut. It is using the same technique but in different directions. For the rectangles it is easier because you do not notice if they all just becomes a bit shorter or longer. But they have been able to draw the faces so that you do not notice it. For example if you look at the chef in the first image he have a black nose and a weird eyebrow. But in the second image he gets a turban and now his eyebrow turns into the bottom of the nose and his nose turns into the mouth. So by drawing it this way they were able to splice inn almost half an extra face without you noticing.",
"Face number 3 in the before shot has no bottom part, face #6 has no top part and the top part of person 2 is just a hat, when it’s moved, a bottom part is added, replacing a bottom face, and the hat of #2 goes on the last guy"
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mdkp8p | Why do we start dozing off at a certain point in the day, but when given an opportunity to sleep later, end up being unable to fall asleep? | Other | explainlikeimfive | {
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"I also wonder this. Reddit are you still sleeping?"
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mdlwe5 | What does the integral of position with the respect of time mean? | While I was studying derivative and integral, this question came to my mind. Position’s derivative leads to velocity and velocity’s derivative leads to acceleration. These guys making so much sense but I can’t define position’s integral in my mind. I looked for the answer on the internet but unfortunately my B2 english level didn’t be enough to understand. Can you explain it like I’m 5? | Mathematics | explainlikeimfive | {
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"Imagine you arrange a race where the contestants all chase someone. There is a decent chance that none of them catch the escapee, but you still want a way of determining a winner. You could choose whoever is closest at the finish but that favours an endurance runner. You could choose whoever got closest at any point in the race, but that favours a sprinter who could get close at the start. So you choose the winner as the person who spent the most time the closest to the escapee. Specifically, whoever has the highest time integral of distance to the escapee. Think of it as the area under a distance-time graph. Maybe this example is a bit contrived, but it is not too much of a stretch to imagine more commercially or scientifically relevant opportunities to use this value.",
"Interesting question. It's apparently a quantity called *absement* which is a portmanteau of absence and displacement. You can use it to find the average position in a given time integral. So, you'd integrate from t1 to T2, then divide by t2-t1, and you'd have the average position within that interval. It doesn't have a direct physical meaning, however. For reference, I got most of this from [this Reddit post]( URL_0 )."
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mdm29x | Why do certain films have age restrictions, but not certain books? | Other | explainlikeimfive | {
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"The age restriction on films are only for commercial exhibition, and play a role as a suggestion for private enjoyment. Most books are not commercially exhibited such as in theaters.",
"There is. Porn magazines are 18+ (or at least used to be). As for novels, etc. it is naturally rated because the books have reading levels. There’s no way a 4th grader can pick up 50 shades and suddenly learn as much as they could with a 10 minute movie scene. Or have the mental imagery from a violent scene in a book be as vivid as a movie. That said, if my kid could pick up and read 50 shades of grey, then power to him. As long as he’s reading.",
"Part of it was how the two industries evolved during a time when people policed social mores and parents restricted kids experiences more than today, and part of it was the amount of work that goes into consuming the two forms of entertainment. For many decades families consumed the first run of films out of their homes in public, and with their family. The social mores were such that they wanted to know for sure if the film they were going to see, or were taking their kids to go see, contained profanity, violence depicted in certain ways, or sex scenes that would have offended them. So a rating system was developed and used to police who could get in, based on their age level. And it's stuck around ever since, although has changed a little. From a young 1960's teen's perspective, watching a 90 minute racy movie was thrilling and some would want to do it. But reading the same movie as a book simply wouldn't be as appealing at that age. There'd be way more work involved and that's something most teens wouldn't want to invest in, resulting in a self-protecting system. So books didn't require as much \"policing\" with an age-related rating system due to their own nature.",
"Books have a built in age restriction system because a 5 year old can't read the book \"50 Shades of Gray\" but a 5 year old could watch the movie \"50 Shades of Gray\". That being said, people tend to forget that block falls apart around age 10. There is also a form of social superiority around books vs movies which is completely unfounded but well established in general society.",
"I have not done much research on this, but I believe that more films have restrictions because they give you an image to look at, which can be disturbing or not child friendly, but as with books with no pictures, that causes you to create your own image of the scene, and if you are younger and with a more innocent mind, your brain will not be able to paint those more inappropriate images. I have read somewhere that your mind is only able to create an image based off of what you have seen before, and it cannot create a new image of something that you have never seen before."
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mdm6lv | if a monitor receives signals at a higher rate than its refresh rate, how does it handle such a request? | I've heard both that it doesn't matter so I should just cap my games and programs at whatever fps my monitor can display or that a higher frame rate than the monitor can refresh "gives my monitor more frames to choose from to display." Which is more accurate? If the latter, how does the monitor select which frames to display? Is there some sort of algorithm or method or is it just random? (Assume the computer and monitor are both fairly modern. Ignore the effects of air resistance.) | Technology | explainlikeimfive | {
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"Your monitor will always receive the frames at whatever frame rate it is running at, or more accurately it will run at whatever framerate it is receiving frames at. If that frame rate is too high (or too low) for the monitor to display, it will simply turn blank, and maybe display an error message - early tube monitors could actually suffer damage from the wrong refresh rate, but that is not an issue for anything modern. That means when your game renders at a frame rate higher than what your monitor is set up to deal with, your GPU comes in. It is what decides what frames will be sent to, and therefore be displayed on, the monitor. Whenever your game renders a new frame, it is written to what is called a \"frame buffer\", which is pretty much a space in the video RAM where the frame to be displayed is stored. Whenever the monitor is ready to receive a new frame, the contents of the frame buffer are sent out. However, it takes time to send the content out, and by the time one frame is done, the next one is already about to start. This means that with just one frame buffer, the new frame may be written while the old one is still being sent out. This means the writing may end up overtaking the sending, and suddenly instead of the old frame, you start sending a new frame. As a result, the bottom half of the screen may show a different frame than the top half, which is known as tearing. To stop tearing, you need to enable vertical synchronization (or \"VSync\"), which ensures that you always have a full frame ready to show. However, you do not know how much time exactly each frame takes to render, so just starting at the right time is not enough. Instead, you use two buffers, and read from one while the other is being written. Once the new buffer is full, you start reading from that one and writing to the other. The problem with this is that you can only write to a buffer after it has been completely read, and only read from it after the *other* buffer has been completely read, so there is a certain delay built into it. So, a modern solution is to have a third buffer. Basically, while one buffer is being read, you are continuously writing to one of the two free buffers or the other, and when a new frame needs to be read, you pick whatever one has been completed most recently. As a result, you can maintain VSync (and therefore avoid tearing) without your frame rate being limited to the monitor's refresh rate, and the delay between rendering an image and seeing it is sort of a compromise between single and double buffers."
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mdmm26 | I read a few article talking about how earth is shifting off its initial axis due to change in it's mass. How is the mass changing when nothing is leaving or entering the atmosphere? | Earth Science | explainlikeimfive | {
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"Specifically it's due to changes in mass distribution. They are referring to the melting ice caps. They represent significant amount of mass concentrated in one area, and now that they are melting the reduced mass in the area while continuing the same momentum is throwing it off.",
"Easy. Things *are* entering and leaving the atmosphere. Earth acquires material from meteors and cosmic does and losses material from hydrogen and helium leaving the atmosphere. The net result is that the Earth looses about 55,000,000 kg of material every year.",
"stuff is leaving and entering. Google \"how much meteor mass in a year\" the result should be an estimated 15000 tonnes. we lose helium and maybe other light volatiles to space. occasionally explosions and eruptions may launch mass into space as well."
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mdoey3 | The ship currently blocking the suezcanal is in the media referred to as "MS Ever Given". However on the ships hull the name "Evergreen" is seen written in big letters. What's the real name/ why has two names? | Other | explainlikeimfive | {
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"\"Evergreen\" is the name of the company, and they use \"Ever < x > \" to name all their ships. It's sort of like how Princess Cruiselines traditionally names all their ships \" < x > Princess\", or how Royal Caribbean traditionally names all their ships \" < x > of the Seas\". Many of the Evergreen ships are an \"Ever *Something*\" class vessel and then they are named specifically... \"Ever *Something else*\". URL_0 URL_1",
"The ship is owned by Evergreen Marine, and so has their name painted on the side. Also painted, in smaller writing, on the stern and bow is the name of the boat, the MS Ever Given.",
"Evergreen is the name of the Company that owns the vessel, EVER GIVEN is the name of the vessel itself. You can even see it painted on the stern of the ship in pictures."
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mdp9su | If smells are made of particles, where do they go? | I was told in school that you can smell things because there's tiny particles from that thing in the air. So if for example someone was cooking a whole pan of garlic while farting like a trooper, and they opened the window to let the smell out, where do the particles go? Do they die or is there a giant stink cloud somewhere in the sky....? | Chemistry | explainlikeimfive | {
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"They disperse and reach such a low concentration per volume of air that they become essentially undetectable. Like dropping a single drop of ink into a swimming pool.",
"They persist and float around a while. Precipitation catches and removes many particles. Some particles get stuck on surfaces. Some particles stick to other particles and settle out. Sometimes they collect into a stink cloud called smog.",
"Basically what happens is that eventually they spread so far into the air that their smell is no longer significant or recognizable. Remember that air, like a liquid, will conform to the shape of its container. If it’s “container” in this case is the air outside, then they will separate from each other so much that you won’t be able to smell whatever it is you’re smelling anymore.",
"I have to admit, that image made me giggle. Most \"smells\" are rather complex molecules. And most of them are also rather fragile. In our world, stuff gets composed and decomposed constantly. Take Cadaverine (NH2(CH2)5NH2). The stuff that makes corpses smell really, really, REALLY awful. Well, to us it's awful because that stench should keep us from eating meat that is already in a decomposing state... and it does that pretty well, if you ever smelled it, you will remember reproducing your breakfast, and lunch, and pretty much anything that's inside your body at this time. Now, of course that stuff doesn't exist forever. It gets broken up by bacteria, or by other influences. You may have heard that tomato juice is good if you have been sprayed by a skunk. Same thing, there is stuff in the tomato that breaks apart the smelly stuff. It's not gone, but the molecules get changed enough that they don't smell anymore. Another thing you might have heard about is that \"stainless steel soap\". Basically a piece of stainless steel that is shaped like a brick of soap, you're supposed to wash your hands with it to get rid of garlic or other stinky food smell, and it works. Of course not by \"cleaning\" your hands off it, but by breaking up the stinky molecules. And it's not really that effective at it. But that's the basic idea behind it. So, no, there isn't some super stinky cloud floating about somewhere. The smelly stuff simply gets broken apart and doesn't smell anymore."
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mdpl2z | What makes cancer so impossible to get rid of? | Biology | explainlikeimfive | {
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"They’re you. Cancer cells are your cells. They carry all the right cellular paperwork and have all the same metabolic chemistry, but they’ve gone insane and are no longer doing their jobs or responding to commands. So how do you get rid of them? You can’t search them out by cell markers, all your cells have the same ones. You can’t poison them, those poisons will kill *all* your cells. They’re cellular terrorists that blend into the population, and you have to selectively kill just the bad guys somehow. What we typically do is pick a poison that specifically targets cells that are dividing. Cancer cells are *always* dividing and so they’re killed in vast numbers. Unfortunately, stomach, hair, and immune system cells are also dividing frequently and get killed off as well. The hope is that the cancer cells are exterminated before the collateral damage elsewhere gets too bad."
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mdqsvx | Why do we sometimes think we have to sneeze but our body just says no | This morning it happened 3 times and I was just so frustrated why in gods green earth would my body do this | Biology | explainlikeimfive | {
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"The “I gotta sneeze” feeling is triggered when a certain type of cells in your nose gets stimulated, for example when you inhale some dust particles. Those cells detect that there is dust in your nose and start sending a signal to the brain that you should sneeze to get rid of the dust. The problem is that sneezing takes some preparation from your body (filling lungs, relaxing some muscles and contracting others, making sure you won’t bump your head as you lean forward etc) and if the excitatory signal from your nose cells disappears before that preparation is finished, your body interrupts the process. The reason behind that is that it takes a lot of energy to sneeze, so if it is not necessary why waste the energy?"
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mdr3uy | Why to some high megapixel cameras in low-end mobile phones perform worse than lesser megapixel cameras in high-end mobile phones and what exactly creates the difference we notice? | Technology | explainlikeimfive | {
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"Megapixels are only one of the factors that determine a good image. Others are optics quality, sensor size and noise levels, exposure time, stabilization, image processing, aperture et cetera. In fact, more megapixels can have a negative influence on e.g. noise, since it means the camera uses more compact receptors. Also mobile phones do a great deal of image processing and high end phones do more than cheap ones."
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mdrndi | CTU ops/ military: how do you make ammunition based decisions before and during a job? | Other | explainlikeimfive | {
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"from my experience in the navy: 1. it is not our decision to make, generally the amount of ammo brought depends on types of weapons and length of the op. ive never gone out like specops way off grid tho. we always had an armory we could go back to. they are very strict about signing out weapons and each magazine to make sure you arent just shooting shit. now that i think about it i cannot remember how much ammo i carried with me. i wanna say it was usually weapon, sidearm, and 4 magazines. if you are going downrange you get your magazines there and carry weapons unloaded. 2. i reload when my magazine is emptied. its really hard to keep track of how many bullets youve fired during a firefight. 3. fairly realistic. if you are calm, cool and collected you can reload like in the video games. the speed is a bit fast. ive seen ppl with super shaky/panicky hands struggling to reload.",
"There's a standard operating procedure for each unit regarding how much ammo to carry on them when on ops. For instance when my unit was in Afghanistan we doubled the ammo amount that we'd carry because we heard about units running out of ammo in firefights... as far as when to reload, it's pretty much up to the shooter. We don't reload after only firing a few rounds because then you'd pretty much be wasting the remaining ammo in the magazine. If you're in a firefight you don't have time to transfer rounds from one mag to another, so normally we'd just fire till the mag was empty."
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mdruws | Why do we have direct and alternating current and what's better? | I know the, both exist and for some devices they need to be converted. But why? | Physics | explainlikeimfive | {
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"When you want to transmit electricity over a long distance, high voltage AC happens to have the least leakage in the transmission lines. And a transformer is a relatively efficient way of converting a low voltage to a high voltage or vice-versa. And a transformer only works on AC anyway. So, we use AC for power generation and transmission. Then, for anything that needs DC, we can just do an AC-to-DC conversion (called \"rectification\") near or inside the device itself."
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mds6vp | On U.S gas prices, why is there a 9/10 next to the price? What does that fraction mean? | Other | explainlikeimfive | {
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"Gasoline is typically priced down to the tenths of a cent, white that last digit always being a 9, so prices end up being \"X dollars, Y cents and 9 tenths of a cent per gallon\".",
"Fraction means nine tenths of a cent in addition to the rest of the advertised numbers. Started off as a gas tax and stations didn't want to round up as it originated when gas was much cheaper and the visual of a full cent up might persuade potential customers to seek a competitor. These days, gas tax is much more, but stations still have the 9/10ths for the same reason a lot of prices in the US end in .99... customers often mentally round down, making them perceive a cheaper price.",
"It is 0.9 cents (or 90% of one cent). Legend goes that it's a standard from when gas used to cost less than a dollar per gallon, many decades ago. The government introduced a gas tax, and the gas companies didn't want to lose money on each purchase but they didn't want to raise the price of gas by several cents (because that would have been a pretty serious increase back in those days) so they raised the price by 9/10th of a cent, to make it a little more palatable to consumers. And that practice has stuck. Not 100% sure if it's true or not. Regardless, it means they're charging almost one cent extra per gallon than you think you're paying (i.e., if the price is $2.01 and 9/10, it looks like you're just paying $2.01 but in reality you're paying much, much closer to $2.02 per gallon)."
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mdsrjl | Why is it hard to breathe when it’s windy? | Biology | explainlikeimfive | {
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"We have a reflex to not breathe in, when what feels like water hits our face. A strong, colder wind can apply the kind of pressure to your face to make your brain think that you're underwater."
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mdtlpf | If light and sounds are made of waves, can we hear light or see sound? | Physics | explainlikeimfive | {
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"Thise are 2 different kind of waves. Light is electromagnetic wave, and what we hear as sound is moving ofbair particles (you don't have sound in vacuum - space). Light is just small spectrum of electromagnetic waves (besides you have infrared, ultraviolet, xray...).",
"Visual perception is dependent on the photoactivation of rod and cone in your eye. Not dissimilar to a flower opening in the sun, your rods/cones 'open' and send a signal to brain when they are exposed to certain wavelengths of light. Auditory perception is dependent on the physical activation of hair-like structures in your ear. Differences in pressure (sound) causes your ear drum to vibrate in a particular way. These vibrations travel different lengths down your inner ear depending on their frequency. Bass-heavy sounds cause low frequency vibrations which travel deep into your ear, triggering all the hair-like structures. Higher frequency vibrations die off sooner and only trigger fewer hair-like structures. Your brain decodes what you're hearing based off how many (and where) the hair-like structures are triggered."
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mdv4r6 | why carbon monoxide poisoning won’t wake a sleeping person. | I may be wrong, but as I understand it, carbon monoxide prevents oxygen from being carried through the body. Why won’t a sleeping person realize something’s wrong and wake up? How is it different from suffocation? | Biology | explainlikeimfive | {
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"Your body reacts to a buildup of carbon *dioxide* when you’re being suffocated normally - you can’t purge the waste product from your blood and this trips all sorts of panic signals. Carbon monoxide poisoning doesn’t impede the release of carbon dioxide, it only blocks the uptake of oxygen. Since the blood carbon dioxide levels never go up, your normal “you’re suffocating!” alarm doesn’t work and you just die.",
"> How is it different from suffocation? Then sensation you feel when you can't breathe isn't caused by lack of oxygen, it's caused by excessive carbon dioxide in your blood. This is why low-oxygen environments are so dangerous. The body has no warning system for low oxygen. You just get sleepy and pass out as your brain starts shutting down.",
"Your body doesn't really have any internal alarms like nerves for pain that would be triggered by a loss of oxygen. It's pretty \"dumb\" in this respect - it gets what it gets and pushes out whatever is left over. Since carbon monoxide itself doesn't cause any unusual sensations (like how a tear gas would cause your eyes to burn, for instance), there's nothing really there to make you realize you're in danger and need to get up and escape. Your body just kinda slows down and then stops.",
"Because you aren’t woken by a lack of oxygen. You are woken by too much CO2. When there is a bunch of CO in your blood you can still get rid of CO2 and so you aren’t woke up. Same reason why if you are in a nitrogen filled room you won’t notice anything wrong and will just collapse."
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mdvroe | why bugs decide to fly straight into my eyes for seemingly no reason other than to piss me off? | Biology | explainlikeimfive | {
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"I’ve always been told they want the moisture from your eyes. It’s very hot and dry where I live and flies sometimes want your sweat or the moisture from your eyes.",
"They don't have a lot of brain capacity. So they don't necessarily see you as an entity, and certainly don't intend to piss you off.",
"You see Billy, when the bug flies into your eye you remember it because it's a special event. The times that the bugs don't fly into your eye don't make it into your memory banks, so when you think of all the times you remember bugs flying, they're mostly flying directly into your eye. It's called confirmation bias.",
"They're attracted to your breath. Mosquitoes and other blood sucking insects especially are attracted to the carbon dioxide you exhale. Plus bugs have a sensory system to find exposed skin. Your face is usually a large section of exposed skin.",
"I’d guess that the simplest explanation in this case might be the best one: you really only notice them when they fly into your eye. For every bug that flies into your eye, there have probably been 100s or 1000s flying into the rest of your body, but you just didn’t notice them."
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mdyqsi | How do they record Voiceovers for movies? Like how do they put the actors on mute, but still keep the sounds in the background? | How do they manage to keep all the other sounds (special effects, music, etc.), while changing the actors' voices? | Technology | explainlikeimfive | {
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"Im not an audio engineer myself, but my friend is and he’s done audio for some small movies and tv shows (although his primary work is music). Native voice audio for movies is often isolated with boom mics so the audio can easily be replaced with a voice over in the final mix. A lot of the background audio you hear is done by foley artists because isolated sounds give you the most control over the final product, especially since a lot of sounds wouldn’t be possible to record without foley (ie. Punching doesn’t make a big whoosh, nor does it make much of a sound in impact).",
"Dozens and dozens and dozens of audio tracks with crazy talented audio engineers mixing it all together.",
"Sound engineer here. Pretty much every sound in a film is put onto a different track which can be turned up or down individually, as well as things like where the sound comes from. When there's a voice over and the actors are muted, it's because everything is controlled separately.",
"Even more mind-blowing: when you see people in the background talking in a restaurant, but can't hear them, it's because they're just pretending to talk. Background actors may have to keep it up for hours while the stars spend multiple takes to complete a scene."
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mdzs88 | If the liquid latex from rubber trees is white, why are car tyres black? | Chemistry | explainlikeimfive | {
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"text": [
"They add carbon to make them black, if they were white they would just get dirty immediately, also black helps with protecting against UV damage from the sun",
"One of the additives is carbon black which essentially is powdered soot. It improves the tires' UV resistance and also increases the hardness of the rubber which decreases abrasion."
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me0kv5 | Why are heating vents positioned right below windows in homes and apartments? It seems like moving them away from windows would make more sense. | Other | explainlikeimfive | {
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"Cold air drops to the floor, warm air rises. By positioning the source of warm air below the window (where cold air is coming from), you make sure that the cold and warm air mix. If you position the heating vent away from the window, you can end up with a layer of cold air near the floor and a layer of warm air near the ceiling."
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me1ani | How does mopping work? | Okay, you have a bucket of water and by immersing the mop in the water then rubbing it on the ground, then putting it in the bucket and repeating somehow the dirt is transferred from the floor into the bucket, even as the water gets dirtier and dirtier. How does this actually work? Is it some form of arcane magic? o\_O | Other | explainlikeimfive | {
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"Water is actually really \"sticky\". The dirt sticks to the water more than it sticks to the floor. Even if the water keeps getting dirtier, the dirt can't \"unstick\" from the water to go back to the floor. Adding soap makes the water even \"stickier\" to help pick up even more.",
"> even as the water gets dirtier and dirtier. You change out the water in the bucket periodically as it becomes too dirty. Mopping the floor with really dirty water isn’t very helpful. But also modern mopping usually involves a press to remove water from the mop head. You take water from the bucket and spread it on the floor to bring up the dirt, then dry the head with the press and soak up the water back into the bucket. It takes the majority of the dirt with it, and it doesn’t really matter how dirty the water is because you aren’t putting the head into the water at that stage.",
"So for one, we know it works because the mop water gets dirtier. How it works is basically how you described it, get the mop wet, (usually with a mix of soap, water, and bleach). Squeeze most of the water out of the mop (you don’t want it to be sopping wet). Using that top attachment on the bucket. Sweep the mop back and forth over the ground, dirt and oil will get Picked up by the mop head Then dunk that back into the water, releasing the dirt into the water In the bucket. And start the process over again. It’s really that simple, and we know it works because the bucket water gets dirty. The kicker is, you can’t keep doing this infinitely, you will reach a point where the water in the bucket is so dirty that the mop head isn’t really releasing more dirt than it’s soaking in. Imagine it like a T-shirt that you got muddy, just putting the T-shirt in some water and rubbing it a bit will get most that mud off. But if you tried to do that with a T-shirt and super muddy water. Then it doesn’t work very well at all.",
"Conservation of Dirty. The mop and water got dirtier, therefore the floor got cleaner. Dirty can neither be created nor destroyed. at the end of the day, you dump dirty water and you wash out that mop.",
"The simplest explanation is that if you run something clean against something dirty, the clean thing will get dirtier and the dirty thing will get cleaner. This happens because dirt just sort of gets everywhere. If you rub a dirty mop against a dirty floor, some of the mop dirt will get on the floor and some of the floor dirt will get on the mop. In this case, you’ve just mixed around your dirt. However, if you rub a clean mop against a dirty floor, the mop has no dirt to spread to the floor, but the floor has plenty of dirt to spread to the mop. Thus, once you rub the mop on the floor, the dirt that was on the floor is now spread evenly between the two. Thus, if you clean off the mop and continue to rub the floor, the floor will slowly get cleaner.",
"1 Sweep up / bare floor vacuum BEFORE you mop. Otherwise you are just making mud from the dirt and dust on the floor. Trust me, don't make it harder than it has to be on yourself. 2 Mop water should be very hot - as hot as you can get in the bucket. This will aid in evaporation. The exception being if you are working on a material that doesn't, for some reason, react well to hot water. 3 Special floor cleaner is mixed into hot water. The type of cleaner depends on the environment being mopped. For example, in a commercial kitchen, the solutions contain degreasing agents to help clear away grease / oil. 4 The traditional mop is going to be a braided cotton or synthetic material that will absorb the mop water and also accumulate the dirt and debris that it runs over. 5 Plan out your route before you mop so you don't \"Paint yourself into a corner\". While the floor is still wet, you want to avoid walking on it because any caked on dirt on your shoes is just going to leave dirty footprints. If you are in a kitchen and using the proper shoes, not a bad idea to hose them off with the mop sink before you begin so you aren't tracking gunk along with you. 6 It's always a good idea to clean out the mop before you get started (Usually there will be \"mop sinks\" that are almost like shower stalls that have a raised lip to prevent dumped out mop water from getting all over the floor as well as hot/cold water tap for filling the bucket). Odds are nearly 100% that whoever used it before you grabbed it put it away dirty. 7 The goal of mopping is not to get a bunch of water spread around - you may need to do this for problem areas but for the most part you are using a damp, not dripping mop to clean up. & #x200B; Now for how you actually perform the task of mopping. With a clean mop, you dunk it into the mop bucket to absorb some mop water. The mop buckets have a (usually removable for cleaning) device that is a spring loaded press. You put the mop fabric into the press and give it a good squeezing so that you are working with a damp mop. Start by placing the mop head on the ground and moving it around in a back and forth wide sweeping motion. If you want to be efficient and not wear yourself out, get your hips involved in the motion so you can make a wider arc. When it gets dirty or dries out too much, clean the mop head in the bucket and begin the process again. You may need to go over places a second time depending on how dirty they are. As you complete areas, relocate your bucket where it is not in your way but still conveniently close. When you are done, dump out the mop bucket into the mop sink and wash and put away the mop where it belongs - usually wall hooks over the mop sink so that drips are contained. Wall hooks are good because having wet mops on the floor are considered to be an insect harborage and will get you counted off on health inspections.",
"So you start with dirt that is stuck to the floor. Hot soapy water from mop releases that dirt so now you have slightly dirty water on the floor. Then the mop wipes up most of the dirty water. Voilá...clean floor!",
"Put down clean water on dirty floor, rub around, pick up dirty water with mop, put dirty water in bucket.",
"The mop on a stick is an ergonomic improvement over kneeling on the floor with a sponge. That's all a mop is."
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me1w7n | Do plants get tired? As in, do they need to take a break from growing? | Biology | explainlikeimfive | {
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"Yes, many plants sleep through the night as they cannot get more energy from the sun. To survive the night, they use their stored energy, ready to 'recharge' when the sun comes back up. They also continue to grow throughout the night.",
"Yes. Growing and being 'tired' are not related, but an actual example of a plant being 'tired' would be a venus fly trap. You can manipulate a venus flytrap to close around an inanimate object. Awhile afterward it will reopen and you can try to trigger it again. Eventually it will be unable to close and will need to rest before it can activate the trap once more. Note, don't mess with it too much as this is a high energy expenditure activity for the little plant.",
"It depends on the plants, and how they're adapted. Most are surprisingly resilient and will survive extremes for a while, but not forever. The constant growth will consume too many resources if they aren't fertilized. But this can also make the plants more susceptible to pests/rot. Some plants rely on a dormancy period, where they're not showing obvious growth, but they're consolidating and still metabolizing in some way. Cooking up some flowers or something. But plants sort of operate on a different time scale. I like to imagine they see days like the blink of an eye, and seasons are more like days to them."
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me33ff | How do pulse oximeters work? How does it measure oxygen from your finger? | Technology | explainlikeimfive | {
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"Technically, a pulse oximeter measures hemoglobin saturation, which corresponds to oxygen saturation generally, but can be erroneous because it also responds if your hemoglobin is saturated with e.g. carbon monoxide. The device works by having two light sources in it. One of these lights is in the visible spectrum, and one is in the infrared. The device measures how much light is transmitted from one side to the other, but more importantly, measures the ratio between how much visible light is transmitted vs how much of the infrared is transmitted. Oxygenated hemoglobin absorbs infrared light and passes visible light, while deoxygenated hemoglobin does the opposite. So, while the total amount of light transmitted can vary based on the thickness of your finger or how exactly the device is clipped on, the ratio between the two remains consistent."
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me3ckt | What’s the difference between ontology and taxonomy? | Other | explainlikeimfive | {
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"Taxonomy is the study of how we classify things. Ontology is the study of the purpose of existence and reality."
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me40pr | What is the difference between LTE and 4G? Is one “better” than the other? | Technology | explainlikeimfive | {
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"LTE is one of the 4th generation cellular networking technologies, and the only one in common use these days (WiMax never really took off), although some devices may label hspda+ as a 4th gen cell network technology",
"The difference between LTE and 4G is like the difference between a hammer and \"things you use to put in nails\", they're pretty much the same thing even though pedantic people will point out that not *just* hammers can be nail-inserters. To answer the question, there's no difference, unless you're using your shoe instead of a hammer, in which case the hammer is better.",
"4G is a very broad term that refers to the that generation of mobile technology. Kind of like cars, Honda = 4G. LTE and Wimax are examples of different and competing 4G technologies, kind of like the Accord vs Civic."
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me4h8s | why does hot (spicy) food leave an after affect of burn or taste but no other food does. | Biology | explainlikeimfive | {
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"The burns in most of it comes from capacascian(which I can't spell) which is oil based, and not water soluble, so it remains and keeps burning till it's all removed or soaked up or replace by some other oil.",
"So theoretically you could make the burn go away with swishing another oil? About to make some hot wings and gargle olive oil lol"
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me6edx | Why are chimpanzees significantly more muscular than humans, despite lower testosterone levels? | Adult male chimpanzees have on average 397 ng/dl testosterone, which is below the human male average, yet they have virtually no fat and carry a significant amount muscle mass. Which genes/hormones allow chimpanzees the ability to pack on so much muscle with so little testosterone? | Biology | explainlikeimfive | {
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"Testosterone is simply a growth hormone - when cells detect it, they transcribe certain genes that cause cell division. Testosterone is just one part of that puzzle. Every single protein involved in taking that testosterone signal and causing gene transcription is a gene that can mutate, and there are a *lot* of steps involved, so lots of places for potential mutations. If any step of that signalling cascade is more active in chimpanzee muscle cells than in human muscle cells, it would lead to chimpanzee muscles having a greater response to testosterone.",
"Chimps also have much denser muscles than humans (you won't see them swimming) also their muscles are attached and levered differently to ours allowing greater strength."
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me710f | why are nuclear explosions so huge? | what about the way nukes work makes the explosion so tremendous? i know nuclear explosions are big, but what makes them big? | Physics | explainlikeimfive | {
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"The energy released during the interaction of nuclei is much higher than that of full atoms. One atom splitting releases way more energy than one molecule of TNT decomposing. So, you get 600,000,000,000,000,000,000,000 of them together, and the nuke is going to release way more energy. That energy, in both cases, causes heat and violent expansion.",
"When a nuclear warhead detonates, a chemical explosive compresses nuclear material (likely isotopes of uranium or plutonium) which causes the nuclear material to undergo fission, which just means atoms smash into eachother with such force that the nucleus is broken apart causing energy to be released. One atom may not release a large amount but the collective of trillions of atoms produces tremendous amounts of explosive nuclear energy. The heat generated at the moment of detonation will reach temperatures 5 times that of the core of the sun, which is approximately 27 million degrees Fahrenheit. Fact: less than 2% of the uranium inside the little boy bomb, which exploded over Hiroshima in 1945 actually reacted.",
"The short answer is that nuclear explosions are so large because they release so much energy. Are you familiar with the famous equation E=MC^2 ? Energy = Mass x Speed of Light (squared). That tells us that energy and mass can be converted. Chemical reactions like TNT exploding convert a tiny, tiny, almost infinitesimal amount of mass into energy. Nuclear explosions are way more efficient and convert a lot more of their mass into pure energy (still not a lot in the grand scheme of things)."
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me797z | Do our thoughts have any physical attributes? And if not how do physical building blocks like molecules and such create something that’s no longer physical? | When I listen to the little voice in my head, what changes are being made in my brain? I know if I think of a happy memory, dopamine will be released which is what makes me feel happy. But what causes the dopamine to set off in the first place? Everything we know is built from fundamental laws of matter but then how is our thoughts and our consciousness explained? *Explaining Flair: I guess it’s chemistry and biology i didn’t know which one to choose lol | Other | explainlikeimfive | {
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"What you're asking really cuts across a few disciplines - empirical ones like chemistry and biology, but also some philosophical topics, especially ontology and metaphysics. These are the branches of philosophy which deal with questions like: what kinds of things exist? Just material? Or mental things too? What do we even mean *by* exist? Do things like numbers and patterns 'exist'? Depending on your answers to these questions, your descriptions of the universe and the things and people in it, may have very different foundations. Like, say you have two apples. Certainly the apples themselves, the physical material that they're made of, *that* has physical existence. But what of the 'two-ness'? Do the laws of physics really know or care that this collection of atoms counts as two objects? What if we decided to call it four half-apples instead? eta: Or what if I even said \"There's no such thing as apples, that's just 18 bazillion atoms hanging out near each other.\" I know it sounds like i'm being silly and splitting hairs here, but this is just meant to demonstrate that there can be different ways of describing the same physical state of affairs. And that kind of ambiguity is *powerfully* at work when we're talking about mental states of affairs in your mind, and physical states of affairs in your brain. The 'two-ness' of 2 things is tractable, but it can get very slippery when we start talking about collections of billions of neurons. And if our thoughts and feelings are *patterns* in those collections, well, good luck. So to say that the release of dopamine *causes* happiness is one way of looking at it, and to say that the release of dopamine *is* the happiness, is another way, or you could say that the happiness exists as some kind of complicated logical dependency between the dopamine and a bunch of subsequent neurochemical events going on in there.",
"We understand how one neuron sends signals to another and a basic idea of the function of different parts of the brain, but how this all connects to create thoughts and consciousness is beyond our current understanding. The current understanding is that our thoughts are represented by patterns of electrical firings of neurons and the different patterns and connections are what differentiate one thought from another. We can look at a functional MRI and see that different parts of the brain activate when we're thinking different thoughts or performing different tasks. But, the exact nature of how neurons firing creates thoughts isn't known."
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me79qi | Why are large, colorful hardcover children’s books a fraction of the cost of most novels? | I understand that novels use much more paper. But I can’t imagine that outweighing the cost of ink used to print the many illustrations within a children’s book, the hardcovers, etc. Maybe I’m wrong. Please explain like I’m five! | Economics | explainlikeimfive | {
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"The cost of selling books is the content, not the physical materials. It takes longer to write and edit novels or non-fiction books. Also, books for adults are more likely to be loaned to others while kids books tend to be kept and reread until the kid destroys them.",
"It’s an issue of volume. Novels usually have a small, niche audience. They don’t expect to sell very many copies overall, so they have to charge a little more. Children’s books, on the other hand, have a huge market. They are often destroyed and must be replaced, doting parents and teachers buy many, many different books to best grab a kids attention."
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me89r6 | Why can we run over 1 tile gaps in videogames | Technology | explainlikeimfive | {
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"A lot of games have a 'grace period' after you run over an edge where you can still jump. In those games, sometimes the grace period is long enough that it lets you run across small gaps. This period of time is sometimes called 'Coyote Time' as in the Road Runner cartoons.",
"Most platformers have a certain amount of «coyote time», named for Wile E. Coyote, built in to make the game a little less frustrating for people who might have trouble hitting the jump button right on time, whether due to lacking skills, physical impairment, or hardware lag. This means that occasionally, the game gives enough leeway to just run across narrow gaps entirely before gravity kicks in.",
"This is a mechanic there to make playing the game easier - when leaving a platform you have a short time where you still count as \"grounded\" - you don't fall and can still perform jumps. This makes the timing of hard jumps a bit more forgiving. The mechanic is called [\"coyote time\"]( URL_0 ) and exists in most platformers."
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me9rr1 | The role of Testosterone, Luteinizing Hormone (LH), and Follicle Stimulating Hormone (FSH) in the female and male reproductive systems. | Biology | explainlikeimfive | {
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"In a very ELI5 way: Testosterone is a hormone produced primarily in the testes of males, but also a tiny bit in the adrenal gland of both males and females and in the ovary of females. It’s the hormone that makes a child’s body turn into a man’s (Adams Apple, body hair, deeper voice etc) but it also plays a role in bone growth and sexual behavior. A lack of testosterone can lead to fragile bones and low sex drive in both males and females. LH and FSH are hormones produced by a small gland in the brain called the pituitary. Both males and females produce it. FSH (follicle stimulating hormone) stimulates the ovary to release an egg cell, and stimulates the testes to produce sperm cells. In females it is released in waves each month which correspond to the menstrual cycle: high FSH lead to the release of an egg cell and correspond to the fertile period. LH (luteinizing hormone) works hand in hand with FSH in females to trigger ovulation, and has the added role of triggering the ovary to make a corpus luteum. This corpus luteum secretes progesterone, which is the hormone that tell your body that you are pregnant. When the ovum is released, the body sort of defaults to pregnant mode for two weeks, after which it expects to get a hormonal signal from a fertilized egg cell that it is there and ready to turn into a baby. If that signal doesn’t come (either because no egg was fertilized, or because it failed to send the signal) the corpus luteum disappears and progesteron secretion stops. The body prepares for a new cycle by menstruating. In males, LH stimulates the secretion of testosterone in the testes. To sum up: testosterone = male hormone that triggers the changes we see in puberty. FSH = makes females ovulate, LH = helps with ovulation and ensures progesterone production for 2 weeks before menstruation It’s all quite a bit more intricate than that but this is about as ELI5 as I could keep it."
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meavqk | Why does it snow and not hailing when its freezing outside? | Physics | explainlikeimfive | {
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"Hail requires a pretty specific temperature in the atmosphere. When it's cold, water begins to freeze. This causes ice crystals to form. These crystals stick together and form snowflakes. Eventually, these become heavy enough that they fall from the sky. Hail is a bit different. For hail, a small raindrop begins to form. This then begins to sink to a lower cloud level. Here, the air is freezing, so the raindrop freezes. But, because ice is less dense than water, the frozen drop can actually move back up to the warmer, wet layer of clouds. Here, it collects more water, which makes it sink back down. This water freezes, making it less dense so it floats back up. The hailstone keeps going up and down between these layers of cloud, building up layers of ice like a gobstopper. So, for hail to form, we need it to be just around freezing in the atmosphere. Too cold, and that water layer doesn't exist."
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meazfx | How can nothing be faster than light when speed is only relative? | You always hear this phrase if you watch something about astrophysics 'Nothing can move faster than light'. But speed is only relative. How can this be true if speed can only be experienced/measured relative to something else? | Physics | explainlikeimfive | {
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"This is a brilliant question. It is the question the led to special relativity! Motion is relative: the velocity of an object depends on the velocity of the thing measuring it. Speed of light is not relative: everything measures speed of light the same. That is the paradox. The universe tells us that is the way it is when we measure it! ...and we try to explain why. But I believe understanding should start there, not with explanations of space time.",
"You can even think about it this way: The \"speed of light\" is really just \"THE speed.\" It's the default speed of everything. It's just that matter gets in the way and makes things slower. But when all those limitations like matter or external forces or whatever are eliminated, the speed of light (also just called \"c\" in equations) is the speed it would go.",
"Wow, OP. You've asked the very same question that Einstein asked himself to come up with one of the most revolutionary ideas in physics! You are correct that speed is relative. If I'm walking up an escalator at 2 m/s and the escalator is moving at 5m/s then my speed relative to a person standing still at the bottom of the escalator is 7 m/s, but to someone else on the escalator who is standing still and waiting patiently for the escalator to transport them to the next floor my speed is 2 m/s. But light travels at the same speed from all perspectives. Say a spaceship is traveling at 90% the speed of light. If I shine a torch from the back of the spaceship to the front and someone on the ground can see through the spaceship's window, then the light from the torch will appear to move at the speed of light to both of us. But the escalator example would suggest that to the person on the ground, it should be traveling at 90% of the speed of light + the speed of light i.e. at 190% of the speed of light. So how can it appear to move at the speed of light to both of us? Well, if the person on the ground is looking through the window and everything in the ship (including not only the beam of light from the torch, but the people inside the ship) is moving in slow motion, then the beam of light can appear to move at the speed of light. Mind blowing, eh? To solve the paradox, time must be relative! Time inside the ship appears to be slowed down to the person on the ground, and conversely everyone outside the ship looks like they're running around like ants to the people inside. Actually, there's a bit more to it than that, since distances are affected too. But thinking about it like this is a good starting point.",
"Speed of objects is relative when measured from different viewpoints, but not in the case of light. Light is measured at the same speed regardless of the viewpoint of the observer. That's part of the principle of relativity. I'm not a physicist, but I think it works thus: 2 spaceships, one stationary and one travelling at 10000kph, both turn on their spotlights at exactly the same moment, pointing to a stationary observer placed mid way between them. In theory, the light from the moving ship should arrive at the observer sightly earlier, because it has a 10000kph running start. However, the observer will measure the speed of the arriving light as exactly the same from both ships. As the distance between the objects is objectively known, then the only way that physics can accommodate the consistent speed of light is to allow time to distort. Time moves slower for the speeding spaceship to allow the light to arrive at the same time as that from the stationary ship. Edit to answer the actual question! Light has no mass. Everything else has a mass which requires energy to accelerate it. As an objects speed increases, so does it's mass. Increased mass requires increased energy to accelerate it. This becomes exponential as the object approaches light speed, meaning that the object requires an ever increasing amount of energy to accelerate it. This becomes an impossible achievement just short of the speed of light. E=mc2 is the equation that states this principle.",
"I must be 4. I've read most of the comments and still can't understand what people are saying.",
"We used to measure how far one traveled across the seas in 'leagues' and how deep the water was in 'fathoms.' (short side note: 20000 Leagues Under the Sea does not mean 20000 Leagues below the surface of water, but rather travelling such a distance while submerged. It is approximately circumnavigating the Earth in a sub, essentially) We had one unit of length for horizontal distance, but another unit of length for vertical distance. But of course they're really the same thing, just different units, so we know we can convert one of them into the other. There are about 3038.6 fathoms in one league. Let's imagine another scenario where we used km for measuring distances north/south, and miles for measuring east/west. Again, same 'thing' being measured, just in different directions. I face north and now in front of me is km, and to my right is miles. But if I turn some amount, now in front of me is some weird mix of km and miles and so too to my right. The units mix up a little together according to some trigonometry rules. This, at its heart, is what we mean when we talk about space-time. Meters and seconds *measure the exact same thing.* Just as meters and inches do, meters and seconds do as well. There's a conversion factor to tell you how many meters are in a second 299,792,458 is equivalent to 1 second, there's about 1.08 Trillion meters in an hour. That's what that number really means. We'll get to why it *happens* to be the speed of light in a bit. When I lay out my grid of meters and seconds, in all my \"space\" dimensions using meters, and my \"time\" dimensions using clocks, everything looks fine. A meter is a meter, a second is a second. You stand beside me and you lay out your grid, and you agree with my grid. However if you are moving relative to me, your motion acts like a 'rotation'. You still see a second as a second, a meter as a meter. I still see them as the same, but when we look at each others' grids, we each see the other person is mixing in a little of the 'time' dimension with the space ones and a little of the 'space' ones in with time. We each appear a bit shorter or 'flatter' along the direction of motion, and we each see the others' clock as running a little bit slower. As we go faster and faster that disagreement about rulers and clocks becomes more pronounced and leads to other interesting effects, namely ways we have to change how we calculate certain things physically because what we thought to be a good description of things was only valid at low speeds. Here's what ties it all together. We are, all of us, moving through space-time at 1 second per second. That may seem like a tautology or something simple, but think about what it \\_really\\_ means if space and time are the same thing. If I am going 1 second per second always, and I want to start going 30 meters per second, I'm going to have to take those 30 meters out of that 1 second per second. I'm going to have to take some of my travelling toward the future in time and turn it into 'moving' through space. The best I could ever possibly hope to do is to convert *all* of my 1 second per second into 299792458 meters/second. At which point I've stopped 'going into the future' and am entirely moving through space. There's a bit of a catch here though. Having mass means (for reasons) the closest I can ever do is get \\*arbitrarily close\\* to 299792458, but I can never \\*quite\\* get there. If I had precisely no mass, I could do nothing \\*but\\* travel at that speed. Light has no mass. So light \\*always\\* travels at the 299792458 m/s. So far we only know of two other things we think to be massless. Gravity (if it is particles, then gravitons) is massless, and the particles of the strong force, gluons, are massless. Gluons don't travel very far at all, so we don't often think about this, but gravity, changes in gravity, travels at 299792458 m/s. (Gravitational waves for example). For more from back when I was really active about this stuff: [ URL_2 ]( URL_0 ) [ URL_6 ]( URL_1 ) [ URL_7 ]( URL_5 ) [ URL_4 ]( URL_3 )",
"The explanation that worked best for me: the speed of light is not so much the speed of *light*, but of *causality*: nothing can cause an effect on something else faster than that speed. Since light is not limited by anything (at least in a vacuum), light travels at max speed of causality, ergo, the speed of light is the fastest that anything can go.",
"The speed of light always appears to be the same relative to you regardless of your speed. It's the exception to the rule. Space-time compensates to make this true to every observer.",
"The speed of light is constant relative to everything. What Newton - and later, Einstein - showed was that there is no underlying reference frame; all motion is relative. Light differs only in that everyone perceives light to have the same relative speed; 299,792,458m/s in a vacuum. The speed of light is also constant, in that it doesn't accelerate by adding velocity but instead instantly starts traveling at it's maximum speed.",
"Imagine a motorbike speeding down the highway. Its speed is relative to the rotation of the Earth, or someone standing still. Now, the motorbike turns on its headlights. The light beaming out from it moves at the speed of light instantly regardless of how fast the bike is moving. The bike’s speed is not added to the speed at which that light travels. The speed of light is not relative, that’s why it’s special.",
"You can view it as \"the speed of light is the speed limit of the universe\". Nothing (so far) can go faster than that. Because of mass, or lack thereof for the case of photons, as zazieely said. No matter what you try to do to them, they always go as fast as they can.",
"Hey mate, I defend for my Ph.D. in physics in a month. This explanation is not ELI5 but, unfortunately, it doesn't seem like the more elementary explanations are really that, explanations. Rather... just kind of rehashing different ways of saying \"yup that's just how it is.\" So a little more detail may be needed. The paradox seems to arise because of how you're used to looking at relative velocities. If you're driving in a car, someone looks like they're going backwards to you at the same speed that you're going forward to them. And if you introduce a third object, moving at half your speed in the same direction, then you see it as moving backwards at half of your speed while the ground observer sees it as moving forward at half your speed. This type of shifting between different points of view (reference frames), where you can just add or subtract velocity differences, is what's called a [Galilean Transformation]( URL_2 ) and does a good job at describing different the points of view as we humans perceive them. To us also, the differences in velocity between us and other things we see from day to day is extremely small compared to the speed of light. So the difference in the effects between light appearing to move a bit slower or faster in different frames (what a Galilean transformation prescribes) versus light actually always being the same speed, are extremely small. But it just so happens that some people [1]( URL_3 ) [2]( URL_1 ) from ~1850-1900ish figured out that light should actually appear to always be moving at *exactly* the speed of light in any frame, not just approximately. This obviously contradicts the Galilean transformation since the simple addition of velocities between frames isn't satisfied anymore. The ability to mathematically shift between different points of view without changing the underlying reality is called symmetry. Its the same idea that if you rotate a ball it looks the same all around. Galilean transformation is a form of symmetry. It was found that there's another form of symmetry for changing frames of reference called a [Lorentz transformation]( URL_0 ). The Lorentz transformation functions very similarly to the Galilean transformation when things are moving slowly relative to each other when compared to the speed of light. But it also doesn't break down when account for light having to always be the same speed in every reference frame. Since the Lorentz transformation accurately describes reality, its differences with the Galilean transformation have implications on the way that we have to frame our physical interpretation of the world. Among other things, it implies that the coordinates of length can expand and contract as seen in different reference frames, and that the concept of time, which was formerly thought to be a distinct entity, must be treated similarly to position. In other words, time is, in some ways, a 'fourth spatial dimension', and just like space under the Lorentz transformation, it can \"shrink\" and \"expand\" and observers may \"rotate\" towards and away from the \"time\" axis, just like you can turn left and right when you walk. Consequently, the paradox of the speed of light seeming to be the same to all observers is accommodated by the notions of space and time changing for observers to preserve the speed of light from every point of view.",
"It is hard to ELI5, but here goes: You are standing beside a train, you shine your flashlight at someone else standing beside their train, they shine their flashlight when they see yours. You measure the time for the round trip, you get the speed of light. You both get on your trains, heading toward each other. You shine your flashies, you measure the round trip.. wow, same speed of light. You both go real fast, say leaving the station at half light speed each toward each other. You shine your flashies, you measure the round trip.. same speed of light. Now, the reason for this complicated, but essentially your point of view, your perspective, is where all the distances and times are measured from. And those numbers don't work by adding up, when they get closer to the speed of light, the figuring starts to distort. For example if you hop on a spaceship and head toward a distant planet and start accelerating. The rest of the universe, including the distance to that planet, will seem to get shorter (not just because you are moving that way). Essentially you turn everything into pancakes. But, people on that other planet see that happening to you. The takeaway, is that is actually how movement works, our ability to add and subtract distances and speeds is actually the weird little simplified version of reality that we get to live in.",
"This is a great question. You have identified the discrepancy that leads to the twin paradox. Imagine you are floating in space and you see your friend zipping past you at 10 km/hour, holding a flashlight pointing forward. You measure the speed of that light relative to you, and see that it’s the speed of light (c). So it seems like the light should be moving c-10 relative to your friend, since she is catching up to it a little. But when she measures the speed of the light relative to her, it is also c. She sees you zipping backwards at 10 km/hour, so it seems to her that the light should be moving c+10 to you. But you each watch each other take the measurement, and watch the other get c. How can that be? The answer is that from each of your perspectives, whatever the other person is using as a measuring clock must be distorted, so that the calculation comes out the same. So each of your time is distorted relative to the other one. It’s not actually the velocity that distorts time. It’s acceleration. If you two were once standing still relative to each other (and you are friends, so you probably were) then one of you had to accelerate at some point, and acceleration (which has the same effect as gravity) slows time. It’s important to note that in this scenario, you will never meet to compare notes (or ages) because you are flying away from each other. In order for you to meet up again, someone needs to change velocity (accelerate), in a way that gets you back into the same relative frame of reference. The end result of that will be that whoever experienced the most acceleration will end up younger when you meet, because their clock slowed more.",
"This is long, but it breaks down the problem/answer in details. The rule concerning the speed of light, more specifically, would be that nothing can travel faster than the speed of light *relative to you.* Now, you as an observer to something else, would be what is referred to as a 'reference frame'. Think of yourself as the big clock in town square that everyone else uses to synchronise their own wristwatches. You're the baseline, the standard, the metric against which other things are measured, because as far as you're concerned, you're the centre of the universe. You and your outwards perception of the world is simply **zero.** All speed is relative. If I'm standing still and a car whizzes by at 100mph, then I see it moving at 100mph. But if I'm in a car next to it that's doing 95mph, then I only see that car inch forward at 5mph. Any speed you experience is the relative difference between you and all other moving things. Are you moving forward at 95mph, or is the Earth is turning backwards at 95mph? There is literally no actual empirical way to answer that question, because physically there is no difference. Meaning, if I travel forward at 10mph and something else travels towards me at 10mph, it feels the same as if I'm staying still and it moves towards me at 20mph, right? Correct. Two cars moving towards each other at the same speed would takes the same amount of time to collide as one car staying still and the other car moving at twice the speed. The relative motion between the two is identical. So, if I'm moving towards a photon at 1mph, and that photon is moving towards me at the speed of light, then the relative speed between us is the speed of light +1mph, right? Nope. It's just the speed of light. If one of the two objects is moving at the speed of light, the speed between you and it is only *ever* the speed of light. It doesn't matter how fast you're moving. 0mph, a million mph, it simply makes no difference. This phenomenon sounds like a space-breaking paradox. If it works at 100mph, why not an arbitrarily high speed? What happens, where's the shift? Despite the oddness of it, this behaviour is an absolute proven fact, as sure as gravity pulls you down and the sky is blue. Even if you move towards something travelling at the speed of light and that something moves towards *you* at the speed of light, the relative speed between you is... still just 1x the speed of light. This trippy phenomenon is called *frame invariance,* and is the founding principle on which Einstein based his theory of relatively, which describes how time is relative and is not static between two different frames of reference. Frame invariance says everything I've described in a single sentence: *\"The speed of light is invariant* [does not change] *between inertial* [no acceleration; constant speed between the two] *frames of reference\".* So, the two assertions you've made - that speed can only ever be relative and that nothing can move faster than light - are both true, both at the same time. If you're moving towards something at the SoL and it moves towards you at the SoL, the speed between you is still just the SoL. It would take the same amount of time for that photon to hit you as if you just stood still and waited for it to arrive. If you were travelling alongside a photon at the SoL and you were just ever so below the SoL, it would still move away from *you* at the SoL. It would move away from a stationary observer at the SoL, even though you're moving relative to them, and so on. It makes no sense, but our monkey brains simply are not equipped to conceptualise how seemingly broken physics starts to become when you approach speeds this high.",
"A simplistic (and possibly not 100% correct way, but close enough) way to think about it is mass is the main limiting factor on how fast you can go. The more mass, the more energy required to move it. Light has no mass. No mass means you basically go infinitely fast for zero energy. Nothing can actually go infinitely fast, there is a maximum speed limit. Lightspeed is that speed limit. It goes the fastest it is possible for anything to go. Since you can't go lower than zero mass\\*, nothing could possibly get faster than it. \\* There is such a thing as negative mass, but for the purposes of the above paragraph, it is more like positive mass that moves backwards: [ URL_0 ]( URL_0 )",
"Here is the best explanation I've ever seen: URL_0",
"Correct me if I'm wrong, isn't the universe expanding faster than the speed of light? I thought i read that somewhere",
"The best explanation I have heard of special relativity cam from Gavin Free of Rooster Teeth: \"Space and time warp to keep the speed of light constant.",
"You probably won't like this answer, but it's a postulate. It's like an axiom, you just accept it and move on. You see what Maths follows from that and check it in experiments. If there are no contradictions in Maths and you can make predictions from it which are verified by experiments, it's all good. For maximum speed of the light all check outs, nothing is observed faster then it and predictions (time dilation, length contraction...) are verified repeatedly by different experiments and different versions of same experiments, so we can safely say there exists a finite speed for information, which is also the speed light travels with in vacuum.",
"Hi. I'm a physicist. You won't like this, but trying to ELI5 this is futile. Famous scientists have struggled with this question. For me, this is a question about *geometry*. The constancy of c, the speed of light, is is a property of the geometry of spacetime. There is a unity between time and space, and this gives us a constant c. If you're curious, the [Wikipedia article on Minkowski space]( URL_0 ) is pretty good, but it's not for 5-yr olds. There's a book called Spacetime Physics if you're really curious. You can download a pdf for free. Lastly, if your answer is hundreds of words or more and would fill a page and takes more than a minute to read, it's not ELI5 level, is it?",
"Trying to be real ELI5: Everyone has a clock that they use to measure time, so they can use it to measure the speed of things. However the clock is special. The faster they move in space, the slower their clock becomes, but they usually don't realize it because everyone around them moves at similar speeds so their clocks are different by only very little. So while everyone's speed is relative to each other in the normal way, it is also affected a little bit by their clocks changing pace. Now, it turns out that light is the only thing that everyone agrees moves at the same speed, regardless of how fast they are moving in any direction and how much the clocks are changing relative to each other. This is possible because everyone's own special clock slows down depending on how close to the speed of light they are moving. As someone approaches the speed of light, their clock becomes so slow, time really slows down a lot, so that light looks as fast as it normally does when they measure it. And if someone is just staring from far away at another person going really fast next to a ray of light, because their clock is going at their own speed, they will also see light moving normally and the first person moving very fast next to it, but falling behind. So both people measure the speed of light to be the same. And that's why everyone sees light going at the same speed. Basically the personal clocks make everyone measure it the same. Side note: as someone approaches the speed of light, they also become heavier! Moving heavier things takes more energy. So the amount of energy they need to keep going faster and faster increases a lot too, and it increases faster with every little bit of speed added. The math shows that moving at the speed of light would require infinite energy, so no one ever gets there, although they can get very close if they are very light and have enough energy. For example, subatomic particles can get very close to the speed of light, and we can study them by helping them move bear that speed and making them crash against each other.",
"Einstein had the same question back in his day. His famous field equations originally didn't have the speed of light in them at all, they instead had something called the Cosmological Constant which had to be calculated in terms of relativity. This was a problem at the time because it meant the laws of physics would actually change completely with your reference point, which Einstein himself didn't like very much. He famously commented that \"God does not play dice with the universe\" in reference to the subject. ( Though I personally like the Tears for Fears rebuttal to this in the lyrics of God's mistake; \"If he's everywhere, he's in casinos with aces to spare\" ) The Cosmological Constant was considered \"Einstein's biggest blunder\" and the scientific community ultimately pressured him into giving up on the idea and instead capping the whole thing with the speed of light. That's the formula as we see it presented today, with \"c\" included for the speed of light instead of the Cosmological Constant, but that's not the end of the discussion by a long shot. The problem with the speed of light is that it's actually a floating average. It was calculated by splitting up the spectrum and averaging the varying speeds of the various measured wavelengths, which means it suffers from a degree of inaccuracy. This is generally fine for most of the large-scale applications most scientists care about, but it's just enough variation to be a serious problem in questions of absolute precision and the very small. This precision issue has put Einstein's General Relativity at odds with the idea of Quantum Mechanics since its inception, which is why you often see talk of one trying to depose the other in some way, and is also why that quote of his is often attributed specifically to his views on Quantum Mechanics. When the Cosmological Constant is reintroduced to the field equations, it presents an opportunity for certain things from the Quantum world to make sense in terms of Relativity, but the implication of the fluidity of the laws of physics are still pretty unpopular overall. So is it true? Is dice being played with the universe? Whose math is the most correct? Quantum Physicists or Einstein? We don't know. As beings that can barely build rockets capable of traveling to other planets within our own solar system, at excruciatingly slow speeds at that, it's going to be hundreds of years before the technology exists to start putting these theories to the test. At that point, it'll probably look a lot like our attempts to break past the sound barrier. They are completely different ideas, in mathematical terms, but there's a huge amount of crossover in how these two speed limits are discussed within their own respective times and that will most likely lead to similar practical tests. Maybe then we'll have a better idea of who's right but, until then, it's largely just up to what you want to believe. There's definitely plenty of math to go around either way."
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meb2os | Where does wind begin and end? | Earth Science | explainlikeimfive | {
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"Wind is just the equalization of pressure. Air moves from high pressure to low pressure. Think of releasing the air in a balloon.",
"Wind doesn't really begin or end anywhere. It's caused by pressure gradients. The key term there is the last one. Gradients are fields of smoothly transitioning things. This means you can't really define it without setting some sort of cut off point. You can enclose a pocket of high pressure in some sort of zone like a circle, but there isn't a way to define it's shape without some sort of arbitrary limit. Wind happens when you're in an area between pockets of high and low pressure sandwiching you. This area is a smooth transition from high and low pressure and changes constantly due to air moving between the two points. Things naturally want to shed as much energy as possible, so when you have a high pressure area that isn't contained, it will move air towards the low pressure. This is what wind is. What ultimately causes the different zones or fronts of pressure is a very complex system of temperature, albedo (a sort of reflectivity of the air and ground), humidity, etc. This is a very sensitive system so small changes will cause drastically divergent results. This is why predicting weather is a cluster fuck.",
"The atmosphere is made of air. The air moves around because of things like how hot or cold the air is, how much water is in the air, how high or low you are compared to the sea level, and the kinds of stuff in the air (for example sand or car exhaust). Wind is when air moves from one place to another. Hot air wants to cool down. Cool air is already enjoying the cool spot and the hot air coming in pushes the cold air out. Meanwhile this is all happening on a planet that is spinning around. The spin creates swirls. The wind starts wherever the air was sitting that got heated up by the sun. The air ends wherever it's in a cool flat open space. There are a lot of ways I oversimplified it but that's basically my understanding"
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mec0ph | Why do some foods shrink when cooked? | I appreciate that some water can escape but why do the dimensions of the food in question change so dramatically, for example a bacon rasher becomes around one third smaller? | Biology | explainlikeimfive | {
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"As you guessed, the water is being heated and it evaporates. In order to have crispy bacon you need to remove basically all of the water. Raw bacon is about 30% water."
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mecvc2 | How do airplanes create those cloud streaks and how do they stick around for so long after the plane is gone? | Physics | explainlikeimfive | {
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"Someone can correct me if I’m wrong but here I go. Combustion has two main by-products: carbon dioxide and water. These are at very high temperature leaving the turbine, so water is in gas state, which then condensates very quickly because of the low temperature at the height the airplane is in. The streaks you see are basically clouds, and, just like clouds, they stay a long time until they form into rain or until they disperse in the atmosphere."
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medcca | how does our body know wether something is food or not? | Biology | explainlikeimfive | {
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"If you mean digestion, it's all chemistry: the \"food\" part can react to produce energy, the rest can't. No enzyme, cell or organ \"knows\" about something being food, it just processes only the things it's capable of processing, and not the rest. If you're talking eating behavior of animals, it's waay more complicated and out of my scope.",
"Your body doesn't \"know\" anything. Things just happen. If something triggers your taste buds, then it has a flavor. Depending what the flavors are, you may have an instinct to eat it or spit it out. Your stomach tries to break down anything you eat. Whether or not it *can* doesn't matter; it'll try anyway. Your body will then try to extract nutrients from anything your stomach breaks down - it has no idea whether or not it can, but it'll try anyway."
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medmgt | How do we know for certain that we all come from Africa? | Biology | explainlikeimfive | {
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"We don't know for certain, however all the evidence indicates that the rift valley in Africa as being the earliest hominids developed due to the remains being found in that location and the area being suitable for development.",
"We don't know for certain but looking at the DNA from people all over the world will give you clues and those can tell you migration patterns. All of these DNA markers, when analyzed, point back to Africa.",
"Although we will probably never 100% prove we all migrated from Africa, DNA analysis and fossil remains have given a lot of evidence to support this claim. Some of the oldest known remains of our ancestors have been found in Africa"
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medn0e | If I have dry, cracked skin then why doesn’t putting water on it help? Surely moisture is moisture? | Biology | explainlikeimfive | {
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"Your skin wants oiled based moisture to complement the oil it makes naturally. The moment you wash your face with water and leave the bathroom the water has evaporated along with your skin's natural oils. So it is doing the exact opposite of what you believe: dry out your skin even more.",
"Skin needs moisture as related to oils. Water doesn’t help because it is not oily. Think cocoa butter and lotions.",
"Your skin is \"moisturized\" by skin *oils*, not water. Your skin is, generally, waterproof. Lotions are made from oils, which is why they \"moisturize\" your skin more effectively."
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meey7i | What is spintronic and how it work? | Technology | explainlikeimfive | {
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"Spintronics is the study of using electron spin in electronic devices. Basically, electrons have charge and spin, which is a rather complicated concept that you can visualize as an arrow. The direction that arrow points can be changed by magnetic fields. Now, modern electronic devices use only charge. A circuit works by flowing charge through wires, transistors, etc. This is why turning the power off on your computer causes most RAM to lose its information. Without the flow of charge, RAM and processor registers can't save their states. (This is why we need magnetic hard drives or SSDs.) Spin, however, is *intrinsic*, meaning that you wouldn't need to keep power flowing to maintain memory. Spin also points in a direction, which could be useful, since you could (in theory) transmit more information in a \"spin current\" (a line of little spin arrows pointing the same way) than in a charge current. The direction f the arrow could be used as additional information. Spin and charge currents also don't need to point the same way. You could have opposite spin currents with no net charge current! It is also possible that such devices would be far more energy efficient than current circuits. Understanding how to manipulate these spins, how they move, and how they work is what the research field \"spintronics\" is, but the general idea of having circuit devices which use electron spins as well as charge is also called \"spintronics.\""
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mefxn7 | why do humans naturally think small and/or fluffy things are cute? | Biology | explainlikeimfive | {
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"A lot of focus is put on how we have genetically influenced many species to make them more domesticized, in order to serve important roles for us such as pets, livestock, or lab animals. What's weird is that we rarely seem to look inward and realize that we too must have genetically gravitated towards our role as domesticators. One could argue that features that make baby animals cute (such as big eyes, soft features, bigger paws and heads relative to the rest of their body) is just an extension of our instinct to act kindly to the young of our own species. However, and forgive the anecdotal nature of this, human babies--especially those that aren't our own--are just plain ugly when compared to a puppy or a kitten. I would argue what is going on is a genetic drive to bond with these creatures *before* they develop fear based responses in order to aid in our ability to domesticate other species.",
"It’s a natural mechanism to want to take care of our young ones. Children are small and cuddly which makes us go ‘awww let me take care of you’. Vsauce had a great video on this a couple of years ago"
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mefxyt | heat rises, so why is it that higher elevations are usually colder? | Physics | explainlikeimfive | {
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"There are different factors at play. Yes, heat rises when the air is all at the same air pressure. So in a house, the warm air rises toward the top floor. But when factoring 1000's of feet of elevation, there are dramatic air pressure differences and other physics at play. Much of the warmth felt closer to see level is the sun's heat absorbing into the ground and radiating back up. At higher elevations, you're further than that heat source -- think of standing next to a radiator vs. across the room. And with less atmosphere between the mountain top and space, the amount of heat loss of heat to space vs. heat gained by the sun's warmth shifts."
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meg1kw | Why are human life spans not longer? | Biology | explainlikeimfive | {
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"Evolution doesn't have a goal. Evolution just 'rewards' traits that help you reproduce, and 'punishes' traits that harm that. Evolution doesn't particularly care _what_ these traits are, or how they manifest - the only thing that matters is do you live long enough to have kids. There was no selective pressure for humans to live longer than ~80 years, so we don't.",
"There are fascinating biophysics effects that tie the size of a species to its lifespan. For a More detailed explanation, I would refer you to the Kurzgesagt youtube videos on Size of Life (esp #2): URL_0 For a brief summary, in general the larger a creature is, the slower its metabolism. A small thing cools off faster, so a small mammal must eat faster to maintain its temperature. The slower its metabolism, the longer it lives. Mammals have roughly the same number of heartbeats in them. This rule of thumb is useful for comparing similar species, like mammal to mammal. This is why a whale lives so much longer than a human, and something like a rodent lives so much shorter. There are other effects that must be taken into account when looking at vastly different species like a turtle. Turtles are cold-blooded, and in general cold-blooded species have lower metabolisms since they don't internally regulate their heat. As above, a lower metabolism translates into a longer lifespan. Therefore a turtle will likely have a longer lifespan than a mammal of the same size. Interestingly, if you look at other mammals of similar mass to great apes, you would expect great apes to have shorter lifespans. Given the biophysics, I would actually be asking the opposite question. Why do humans live so long? We live easily twice as long as the simple biophysics would predict.",
"While research is not yet conclusive, the prominent theory about lifespan is that telomers (the end of our chromosomes) become shorter and shorter with age. While telomers do not contain any information, when they're all \"eaten up\" by this process, the actual chromosomes, where our genetic information is stored, are partially destroyed. When this information is lost, problems start to arise within the cells as they can't produce what they need without the corresponding genetic information. The accumulation of these malfunctions is shown in what we call aging. At some point these problems become unbearable or the organism becomes too weak do defend itself, we die. There are some organisms that repairs their own telomers in the same rate that they're shortening. Such organisms live forever when they're not killed by external forces. Yes, such things exist. Obviously, this is only about the theoretical limit of life, there are many more factors like external forces (like viruses, cars, pollution) or internal forces (mutations that result in cancer or other illness). Some species are more exposed to external forces than others. & #x200B; On the other comments: * Evolution is better served if you don't have an overpopulation, thus dying has an evolutionary advantage. * Slower metabolism does correlate with longevity but it's an oversimplification. ELI5 is not about simple information but about simple communication. Organisms with slower metabolisms devide their cell less often, resulting in less shortening of the telomers."
],
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11,
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"https://youtu.be/f7KSfjv4Oq0"
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meg29v | How and Why can humidity cause more sweating than heat?? | Biology | explainlikeimfive | {
"a_id": [
"gsgjtnj",
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"text": [
"> How and Why can humidity cause more sweating than heat?? Releasing the sweat does not have any cooling effect whatsoever. It needs to **evaporate**. The vast majority of body heat is lost in the form of evaporation energy. A liquid requires a certain threshold energy - enthalpy - to change into its gaseous form. That's where the body heat disappears. While your body also loses heat by other means (heat radiation and simple heat transfer to surrounding materials), evaporation energy lost to sweat evaporation is usually orders of magnitude bigger. If the air has already reached full saturation of water vapor, any further liquid water will stop evaporating. The sweat will stay in liquid form and not provide any cooling effect. Think of the water vapor within the air as some kind of solution. If you add salt into a glass of water the salt will dissolve. If you keep adding salt the water will reach 100% salt saturation at some point and the salt - instead of dissolving - will stay in its solid form and accumulate at the bottom of the glass. It's similar with water vapor and air at 100% humidity.",
"Basically when it's humid your sweat can't evaporate to facilitate the lowering of the body temperature, so because you're still hot your body tries to keep sweating in order to lower the body temperature. This is the reason why \"wet bulb\" temperatures are so dangerous."
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megsqd | why do different beers tend to be served in different types of glasses? | Other | explainlikeimfive | {
"a_id": [
"gsgwc1o",
"gsgwsbt"
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"text": [
"Mostly dependent on the style, flavor, and intended experience of the beer. Here’s a chart that may outline it URL_0",
"It is mostly tradition and marketing although there are some differences. Some glass styles are just associated with certain types. Others were designed by breweries to help make their beer more distinctive. In theory, certain features like a narrower top and wider middle of the glass might help collect aromas which is something you want for certain styles. The distinctively long and tall curve shape of a weizen glass is supposedly to help accommodate and preserve the head which is an important aspect of that beer style. But really, for the vast majority of beers you are not going to see a huge difference from one glass style to another, and the bar just puts them in that glass either because that is the traditionally \"proper\" way to serve it or it's just better for sales."
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"score": [
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"https://www.homestratosphere.com/types-of-beer-glasses/"
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meh926 | If you replaced your individual lightbulbs with pairs of lightbulbs wired together in series, would that cut the current flowing through each bulb in half resulting in the bulbs lasting much longer? | Technology | explainlikeimfive | {
"a_id": [
"gsgy5hl"
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"text": [
"It would double the resistance, which would effectively cut the current in half. However, doing so may mean that neither bulb has enough current to actually produce light."
],
"score": [
5
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mehha9 | Internal injuries caused by explosion shockwaves | What exactly causes such? I get the aspect that the explosion reverberates waves of energy through the air but I don't get how this would cause internal injuries. Do the waves treat the body like a more dense medium to move through? | Physics | explainlikeimfive | {
"a_id": [
"gsh3wyt"
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"text": [
"That is correct. Wave pass THROUGH the body, a solid medium in comparison to that if air, like a gust of wind. Wind moves air molecules, the pressure of which you can feel on a windy day, and based on the density of the wind, often feel it as cold and unimpacting beyond the epidermal layer. **Shockwaves** travel through the same medium, air. In a narrow region where an explosion happens, for example, moving through the air, the pressure spikes up. Unlike sound waves, which you also feel as the air molecules reverberate on the ear drums. That narrow region where the shockwave takes place is what’s called the **wavefront**, is subject to a violent change in stress, density, and temperature. So it ripples, or **propagates**, from its origin point, faster than sound does. Shockwaves cause changes in mechanical, electrical, and thermal properties of solids. Your body undergoes such changes in state at a violent rate, if it is caught in the propagated shockwave. External injuries Would be caused by solid material impacting and/or penetrating your body. Whereas internal injuries would be caused by those sudden changes in your bodies mechanical/electrical/thermal properties, Shifting your state. That is why people take cover, in order to shield themselves from the pressure having such a change on their bodies. Because your bones and organs include that solid medium, and could be shifted around to the point where you are completely incapacitated. Your neuro electrical apparatus Could be put into shock or even completely damaged. And given the density of the wavefront, Your bodies internal temperature could be spiked as well."
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