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l7pctv | How can the person on speaker phone not hear themselves? | When on speaker phone with somebody the sound of their own voice that comes out is not heard by them. How can the device known not to send their own voice back to them? This even works when you are speaking at the same time. They will hear you but will not hear themselves. How is this done? How does this work? As I type this it begins to sound more and more dumb so ill end here. Please explain. | Technology | explainlikeimfive | {
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"This is one of the big problems in any sort of amplification circuit (speaker phones are a good example). This problem is called feedback. Any time you have amplifiers, it has a tendency for the output to \"feed back\" into the input, get amplified and so on. This results in an unstable system, if you've ever heard the screech from the speakers of a badly set up concert stage, this is feedback gone wrong. Now, feedback is useful if controlled and this is what engineers design for in many situations. But it can be difficult to manage and this is almost an entire branch of study in engineering - that of control systems. In modern digital speakerphones, there is software in the phones designed to eliminate the sound coming from the microphone to be amplified back to the speaker. This is sometimes called echo cancellation. It doesn't happen \"naturally\", this HAS to be designed in for the speakerphone to work effectively. What essentially happens is that the phone \"remembers\" what came into the input and removes this signal before sending it to the speaker. This gives the effect that the person talking does not hear themselves amplified back to them on their speaker."
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l7qz6c | Why do Bluetooth headphones struggle to maintain smooth connectivity with digital devices in some places? | While walking around with my Bluetooth headphones on, listening to podcasts playing on my phone in my pocket, I notice that the connection gets really poor in some places. The content is playing offline so it is not a network issue, nor is this a result of dying batteries since the problem persists with fully charged headphones and phones. The places where this happens don't seem to be visibly distinctive but are predictably bad Bluetooth zones. Is it because of too much EMI (electromagnetic interference) in those locations? | Technology | explainlikeimfive | {
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"EMI would be the first thing to look for. It uses the 2.4 GHz frequencies and is prone to interference from poorly shielded microwave ovens etc. Bluetooth also functions at a fairly low power so it is more easily interfered with."
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l7s6mn | Sound volume of commercials | Why does it seem adds/commercials are always way louder than the show or content you are listening too? | Technology | explainlikeimfive | {
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"Most TV shows will have a dynamic range in their sound - highs and lows in overall volume based on what is going on in the show. The commercials, however, use what is called a compressor to reduce the dynamic range - the compressor sets a maximum volume and then increases _all_ of the sound up to that maximum volume without exceeding it. This means that the perceived loudness is higher than the TV show, even if the actual volume has the same high end limit. They do this to grab your attention."
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l7wzt6 | Why do chargers become “incompatible” after a while, even if it was previously working fine? | Technology | explainlikeimfive | {
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"This is due to Apple deliberately detecting that it is not an Apple produced charger through software updates. When you buy your knockoff iPhone charger, they have reverse engineered the secret sauce (really some handshake done at the USB level**) that the phone queries in the charger to make sure its a legit Apple device. But Im positive there's an engineer somewhere in that big round building in Cupertino, somewhere in the accessories division (hi KOG) who is ~~charged~~ tasked with periodically searching online for knockoff Apple chargers, buying a bunch and then figuring out how they spoof the legit ones and then pushing a corresponding firmware update _specifically to break that_ into the PWM (power management) chip driver in the next iOS build. Im not aware of any other mobile device mfgr who deliberately sabotages non-proprietary accessory makers the way Apple does. Yeah, your Samsung might complain about a new charger you bought at the gas station when you forgot yours at home, but when that happens, its really saying \"I need a 2A charger to charge as quickly as I can, this is only a 1A/500mA charger.\", but it will _still work_... just not as well. **not familiar with the details on specifically how, but some googling suggests they actually put a special but simple chip into the cables/charger that can be queried over the USB data lines (or who knows, maybe over the power lines too... wouldn't surprise me)."
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l7xgzx | how do people get different sounds out of analog circuit based instruments? | Just getting into the wide world of analog synths. I’ve seen all kinds of crazy cool diy instruments. People make their own keyboards, eurorack oscillators and effects, drum machines, etc. I’ve got basic soldering experience and I’ve taken electronic instruments apart for routine maintenance. Recently, I’ve gained access to a makerspace equipped with a 3D printer, laser cutter, and lots of other helpful fabrication gear. This, to me, seems like the perfect recipe for making my own electronic instruments. I’ve seen a few different resources for circuit based instrument diy projects, like websites that outline how to make an oscillator, a sequencer, delay effect, etc., and I’m especially interested in constructing my own analog drum machine (something akin to a [Vermona DRM1]( URL_0 ) or a [SOMA Lab Pulsar-23]( URL_1 ) .) How do people get such varied sounds and effects? Why are there such nuanced differences between similar pieces of gear? Where do I look to find the knowledge necessary to get the sound I want out of circuits? | Technology | explainlikeimfive | {
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"/r/synthdiy Also, by combining centuries of research on signal processing with 70 years of engineering since someone found it funny to play with speaker test equipment. That's just the result of having a lot of people experimenting for decades on the same thing and sharing or stealing their results, and improving upon each other."
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l7y0hc | How people actually pull off new non-profit pages on social media like instagram? | I can understand if you have a business, then it becomes an investment. What about the cases of humor pages or art pages where you don't usually expect get profit? Of course once you get a base and keep providing good content, people will share, comment making it more visible. But how such pages make themselves visible immediately after creation? | Technology | explainlikeimfive | {
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"Word of mouth. You tell all your friends and other people in the humor/art/... business."
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l7yvro | Even with a strong battery why do cars have a hard time starting in cold weather? | I don't understand what is different that prevents cars from starting right up in cold weather. Fuel is present, air is there..spark plugs are ...sparking ..and as long as you have a strong battery the starter is turning the engine...why the struggle? | Technology | explainlikeimfive | {
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"Batteries are powered by chemical reactions that make an electric current as a product. Most chemical reactions occur much slower in cold temperatures. Slower reaction = less electricity generated per second. Less electricity per second means your car can't make enough sparks to ignite the fuel in your engine, which means it can't start. If you have a strong battery, these effects are small, unless you're in like, *really, really* cold weather. **Edit:** Another user pointed out that sparkplugs don't actually carry the current to the engine to make it start. That's done by a separate motor carrying an inrush current. It's still an issue with current, just not with sparkplugs **Edit 2:** Those claiming that engines won't start at low temps because of oil being more viscous or that moving solids are packed closer together and introduce friction as a result aren't *completely* wrong, but it's not the primary reason for this occurrence. The density of a liquid or solid (such as motor oil or the metals used in your engine) does change with temperature, but the scale at which this occurs is not enough to prevent your engine from starting (at least for the majority of cars on the road). It is enough, however, to increase the amount of work required by your engine to do its job, which would increase the current needed to start your engine. You'll also have lower gas mileage when your engine is cold vs warm for the same reason.",
"The oil in the engine gets thicker and harder to move when it's colder, it is harder to turn everything in the motor over to start it, so it turns slower.",
"Lot of people are forgetting that when a reciprocating engine is cold, the tolerances between the moving parts become tighter, meaning there is more friction.",
"They shouldn't have a hard time with a strong batterie. If it is older or just not fully charged for some reasons there can be problems tho, because the capacity decreases with cold temperature."
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l84x7u | If whatsapp says it keeps personal conversations private thru encryption and doesn't read them, how is it able to detect messages forwarded many times? | Technology | explainlikeimfive | {
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"I'm not familiar with the specific method Whatsapp uses but there is at least one method I can think of that would work. Before the client device encrypts the message it also hashes it. A hash function is basically a formula that data can be input into and outputs a relatively short value. This result is unpredictable from the input and very difficult to perform in reverse, which means it is easy to figure out the hash from the data but very difficult to figure out what data would result in a given hash. Another important concept is that hashes are \"lossy\", which means you can't get the original data from the hash. Even if you reverse the hash function you will just find some kind of data that would give the hash result, and there are lots of those \"collisions\" (probably infinite). So if you give out the hash of your message you don't need to worry about someone figuring out your message. By looking at the hash the server can figure out if messages are all the same thing even though they don't know what is actually being said.",
"I didn't test that feature or read on it, so I don't know if they'd also flag messages that are identical but independent. Say - if you and your friends forward a message between eachother and if, independently from you, me and my friends forward a message with identical content just between us. At that point it would be forwarded, has been \"forwarded many times\", is the same message, but might not be considered \"the same\" by the service. Without knowing the internal workings of it...there are several ways to do something like that without breaking encryption, but I suppose the cheapest and easiest is to add a counter to the message sent within the encrypted message that increases by 1 each time the app is using the forward function on that specific message. When that counter reaches 5, the forwarding limit hits ([ URL_0 ]( URL_0 )) and it shows the label. This could theoretically be tampered with, as a sender could manually set the counter lower, but is very unlikely to be done by enough regular users to meaningfully increase the number of forwards to spread misinformation. Other methods could include calculating hashes of the content of a message - a hash function could take message content as input, do some calculation on it, and return a number. Under normal and intended circumstances, this number is unique for each specific message. If you change one character and run the function it again, a different number (hash) will be the result. The result is one-way, meaning you can't take the hash and get the original message back from it by reversing the calculation. Whatsapp could store these hashes and count how often they were used. That way, they wouldn't know the content, but would know \"it's the same content\" as another message with the same hash. Whenever you try to forward a message, it could hash that message and check against its table and count. If they'd use this method, there's that point though that they don't want to flag \"hi bob, how are you?\" that may be forwarded just as well as some misinformation dumbing-down society that they do want to flag instead. edit: typo"
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l87jmx | Why it costs like hundreds of millions to create a triple A game? Where do they spend money other than salaries and copyrights? | Technology | explainlikeimfive | {
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"Programmers are not cheap, and you need a lot of them to build a complex game. Every element of the UI, the behavior of objects in the game world, enemy AI, and so on has to be coded. Assets, like textures and models, take a ton of work to build, and a big game needs thousands of them. A single raid in World of Warcraft, for example, involves something like a hundred models with three or four textures apiece *just for the items it drops*. Add in the enemies themselves, all the environment design, little doodads placed in the game world, spell effects, etc. and you've got something that takes a large team weeks or months to build. And then you have to test all this to be sure it actually works in-game, which inevitably it won't and you'll have to go tweak things.",
"If you have 200 people working on a game for 5 years, and they average $100,000 per person, you’ve hit $100 million right there just in salaries. Some triple AAA games have more people working on them. Some have less. Some pay more or pay less, and some take more time or less time than that. But as back of the napkin math, that should illustrate that because big games take a lot of people with in-demand skills a long time to make, paying them for that work adds up to roughly the ballpark of what you are talking about very quickly.",
"Office space, health insurance, massive amounts of computers, outside consultants, management salaries, HR salaries, days lost due to HR trainings, taxes... Its takes *years* to develop a game and all the overhead adds up fast"
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l88pn3 | How do voice calls work? | Technology | explainlikeimfive | {
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"The simplest way to imagine doing this is by building a circuit which compares a waveform against a bunch of fixed known voltages. Say you have an analog signal ranging from -1V to +1V. By creating a bunch of fixed reference voltages (1V, 0.9V, 0.8V, ... -0.9V, -1V), you can use a simple *comparison* operation to determine which of those voltages your signal is higher than. Say your comparison circuit finds out that it's higher than 0.7V, but not higher than 0.8V. You could transmit this as a `7` to the listener. On the receiving end, a similar circuit (but in reverse) could take this `7` and interpret that by connecting the output signal to the 0.7V reference. By doing this over and over again (say, ten thousand times a second), you can make the voltage at the output roughly match the voltage at the input in basically realtime (as long as you can keep transmitting ten thousand numbers a second). Obviously, real circuits will be much more sophisticated than that. But I hope it illustrates the basic idea."
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l8d63m | What is the difference in hardware between a cpu, gpu, and dpu? | I understand the benefits of using these 3 different types of processing units. I am in need of an explanation of what makes them operate differently and why you need a gpu or a dpu instead of just having a software update to allow a cpu to do similar work to a gpu and a cpu. What is the difference in hardware and software that make them work differently? | Technology | explainlikeimfive | {
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"As an analogy, think of a CPU as a fast car, and a GPU as a big truck. If you want to get from point A to point B as fast as possible, the car is way faster. But if you want to get a lot of cargo from point A to point B, the car will have to make a lot of trips, while the truck can carry it all in one trip. The circuitry of CPUs and GPUs are quite similar in some ways. Both of them are very general-purpose, they execute whatever software instructions they're given. What differs is what sort of instructions they know how to follow, and how they execute them. A CPU's instructions are all centered around doing one thing at a time. The circuitry is designed to execute each instruction as quickly as possible and get the next one ready behind it with as little wasted time as possible. CPUs have a lot of circuits that peek ahead at upcoming instructions in an effort to save time. A GPU's instructions are all around executing the same set of instructions on lots of data at once. You give it an instruction, and it executes that same instruction in parallel on hundreds of separate cores that each have their own slice of the data. That's why GPUs are really great at graphics. Your monitor has millions of pixels. If the CPU wants to turn them all black, it has to do the pixels one at a time. The GPU can do hundreds or thousands at a time."
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l8g1br | DPI vs Mouse Sensitivity | So I've been trying to figure out the difference between "DPI" and "mouse sensitivity", and I'm not even gonna go in to what I've found because it all seems to conflict. I want to know why DPI isn't the same as mouse sensitivity but we use it as such (supposedly 400-800 is good for gaming yet I've been using 2400 and my mouse goes up to 16000). Does the distance a cursor travels at one DPI vary across different screen resolutions? Why would a mouse be able to go up to 16000 in the first place if you wouldn't use it? Is DPI the number of pixels per inch on a screen or how many pixels your cursor moves when you move your mouse an inch? I'm so confused. & #x200B; Sorry if my thought trail seems sporadic, I just kept thinking of new questions as I wrote. | Technology | explainlikeimfive | {
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"DPI and mouse sensitivity are effectively the same thing, however one is a hardware setting and the other is a software setting. DPI is hardware - meaning the mouse's setting. Some mice do not come with customizable DPIs while others do - mouse sensitivity, which is the software-based adjustment of the mouse speed, is used to give you some control when you have a mouse like this. A mouse that actually has customizable DPI settings, such as those that go up to 16,000 DPI allow you to fine tune the mouse to exactly how you want, typically much more effectively than mouse sensitivity because of the # of settings (1-16,000). Why DPI goes up to 16,000 I don't know exactly, it seems a bit redundant to me with the current monitor resolutions. DPI means dots per inch aka pixels per inch. So if your DPI is set to 2,400 then that means in a single inch movement on your mouse pad your cursor will travel 2,400 pixels in that direction. So yes, resolution does make a difference for this. If you play on a 4k monitor for example, a higher DPI will feel more comfortable as playing at as low as 400 dpi on a 4k monitor the cursor will be **very** sluggish."
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l8i576 | what is Heterogeneous computing ? | Technology | explainlikeimfive | {
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"Imagine you and your friend wants to solve some complex problem, like a really difficult quadratic equation with many many terms. With regular computing, your friend is your classmate, skilled at about the same things you are; be it rearranging equations, or doing arithmetic. But the key factor is, that the two of you are both good only at one of the tasks, and mediocre at the other. So you two might have a really good start rearranging the equation to solve for x. But what happens now, is that on one side you have x, and the other side is some complex expression, with large divisions and square roots. This is when things start to slow down. Because none of you are very good at doing arithmetic, progress gets much slower. Now let's consider if instead of rearranging, the two of you were only good at arithmetic. You would struggle for hours trying to solve for x, so that's no good either. Now, with Heterogenous computing, you can instead bring along a friend from a different school, so they might have been learning some hardcore arithmetic while your class was busy with learning to solve equations. So in this scenario, your friend just watches as you rearrange the equation to solve for x, since they are not an algebra person. But when you're once again at the point of x at one side, and lots of arithmetic at the other, your friend can step in and crunch the numbers for you very efficiently! **In real world terms:** Conventional computing uses microprocessors of the same architecture, so they can only be really good at the same thing, but in heterogenous computing, you can employ\" application-specific instruction set processors\" for example. This might be any chip that's particularly good at one, but only one task: be it mining crypto or rendering images of fluffy bunnies. Or you could use a power-efficient mobile ARM processor while idling, only turning on the power-hungry x86 when some heavy computation is needed.",
"I like the other metaphor, but I would change it a little. For a manageable task, like cleaning your bedroom, the task can be completed by a single person, and sped up by getting some help of a few friends. Everyone is in the same area, and can communicate with each other directly to complete this fairly small task quickly. This is similar to what the main processor in a computer does, where each processing core can perform a whole task, or split it up between other processing cores if the software is made that way. This is regular computing. If the problem is much larger, like cleaning up a city after a flood, you may need specialized equipment run by teams. Each team may have many people doing the same thing, like clearing out mud from drainage and homes, removing debris from yards, and hauling away garbage. There is a smalls group at the top managing the process, both tracking results and assigning tasks to the teams working on the larger cleaning tasks. Nothing stops the managing team from pitching in if they choose to. The individuals workers who are cleaning up probably do not have the expertise to manage a large scale clean up. A computer working on a computationally large task may choose to use other resources to speed up the calculations. Computers and mobile devices have a main processor which runs general software well. Now, many also have specialized chips or functionality which is optimized for running certain calculations. If the computer or mobile device is running software which can take advantage of those other resources, the main CPU can let those faster or more efficient resources perform the calculations instead. Most computers and consumer mobile devices have graphical processor units, mostly used for games, but which can also perform general computation. Mobile devices also have specialized circuits called digital signal processors, some of which also perform specific computations that are useful for tasks. The combination of running computer tasks between different processors, like the main CPU and a specialized processor, is heterogeneous computing."
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l8j0ip | What is a seized engine? | I was watching a video on Dunkirk and was told that soldiers would run truck engines dry to cause them seize and rendering them useless to the Germans. What is an engine seize? Can those engines be salvaged? Or would the Germans in this scenario know it's hopeless and scrap the engine completely? | Technology | explainlikeimfive | {
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"When an engine runs without oil, the friction causes it to get extremely hot to the point that internal parts break or, in more extreme instances, the metal pieces weld themselves together. The end result, though, is a 100% dead engine that can’t be fixed in any practical sense of the word. (Sure, it could stripped down piece by piece and completely rebuilt and have any damaged components sorted out... but that’s not practical in the middle of a war. And it’s usually costs more than it’s worth.)",
"Inside of an engine, you have hollowed out tubes and cap-like pieces that fit within these tubes. [Image.]( URL_0 ) Crucial to the operation of the engine, these cap-like pieces must be able to slide up and down constantly. They run pretty much the full length of the tube multiple times a second. If even one of them stops, the engine cannot run, as they are all coupled together. From here on, the cap is called the piston, and the tube is the cylinder. The piston and cylinder must very tightly fit one another. The piston is just barely small enough to fit within the cylinder. Should one of the pistons be damaged in such a way as to begin to grip the walls just right, it can easily become wedged. It will immediately stop. Since it is physically connected to the other moving parts of the engine, and they are moving quite fast, the forces jamming it in are absolutely huge. Things bend, things break, and the piston can become effectively fused to the cylinder. It would be far cheaper to build a new engine from scratch than to repair this one.",
"This is the first post I’ve ever seen where the first ten responses are all correct and not jokes. Yeah to make it really simple: no oil or coolant in a box filled with explosions (an engine) = extremely hot metal gouging itself apart and welding itself solid simultaneously.",
"Engines have moving parts, which is why they need oil to lubricate them. One job of the oil is to dissipate the engine heat. If an engine is drained of the oil, then the heat that gets created by it expands the metal parts until there is no space for them to move about. When these parts rub against each other, they grind together and fuse, or seize up. Then the engine is useless until it can be taken apart and rebuilt properly.",
"Ok, let's try this: A seized engine is a broken engine. Normally, it means that the pistons have jammed within the cylinders (the two parts that contain the exploding fuel) and the engine is locked in place. Yes, they are salvageable, but thats expensive, time intensive and difficult. An advancing army does not have any of these luxuries. The Germans would have tried to fire up the trucks that got left behind and use them, only to find they won't start. Knowing likely what had been done to them, they would have had to proceed without them, rather that waste resources and time on them. Denial of surrendered equipment is always a good idea in wartime.",
"Running an engine dry (of oil) causes moving parts to overheat, warp and bind (seize). Essentially the crankshaft no longer turns. It is sometimes possible to recover but it requires a LOT of work, replacement parts and a good workshop - it isn't something that can be done in the field so it renders a vehicle stuck on the road useless.",
"An engine is seized when it is mechanically impossible to rotate its crankshaft. In the scenario you described, seizure was achieved with excess friction because there was no oil to lubricate the metal-on-metal movement. The pistons probably expanded and warped, becoming wedged inside the cylinders. Besides that, connecting rods and crankcases usually break. When the engine is seized in this way, repair *might* be possible depending on how extensive the damage is, but usually it's so severe that it is both not repairable in the field and more expensive to repair versus replacing outright.",
"Someone drained the oil out, and the metal parts in the engine get stuck together through heat and friction. They expand into each other and is irreversible to fix without some serious, time-consuming work.",
"Engines move very fast. When metal moves fast it gets hot and it gets slightly bigger. Oil stops the engine from getting too hot. The space in an engine is so tight that when you take away its oil, the metal expands and gets stuck together.",
"A seized engine is an engine which does not turn over any more. Even if you try hand cranking them or bump starting them the engine will not physically be able to turn. In an engine there is a lot of metal components moving against each other with a thin film of oil between them to slide on. But if you remove the oil from the engine the metal will just scrape against each other \"dry\". This will make a lot of heat and scrape up the metal. The heat weakens the metal causing even more damage and may also warp it. The end result is often that the metal pieces in the engine which is supposed to be a tight fit is now crashing into each other and the engine does not turn over. If this happens to your car and you notice the oil pressure light turn on and immediately pull over and stop then you might not have damaged any components at all. And even if you did some damage it is possible to swap out those components of the engine and it will be good to go. And in the late 30s swapping engine components were a regular maintenance task so these components would have been readily available. The problem was that most of them were back in the UK as German and French cars were built with different engines then the British cars. In addition the cars were run dry as long as possible which would have likely damaged a lot of the internal components. They might even have damaged the engine block which is the biggest component of the engine. At that point it is cheaper to just get a new complete engine then to replace most of the components of the old one. In any case it would have been a lot of work for the mechanics. So I doubt any of the trucks that were run dry and left on the beach would have ever been operational again. They might have been used for spares to help maintain the trucks that were abandoned intact. It is also possible that some Belgian farmers would get a hold of a few of the trucks and spent a good amount of their spare time getting one of them working again.",
"Metal on metal needs lube. Without it the metal gets too hot and expands. That means your motor is fused together. Congratulations on your new boat anchor",
"ELI5: Engine seize... 2 moving metal parts get so hot that they melt and when they cool down a little the two parts have melted into each other and are now just 1 non-moving part.",
"Seized means stuck. They make the engine stuck so it doesn't move anymore. In most cases doing it this way, the engine is no good anymore. Because it damages the block that everything on the engine is attached to!",
"An engine is usually seized when it locks up due to a number of reasons, but in this case they'd drain the oil and coolant causing major damage. First the engine overheats and causes the block and heads to warp making it pretty much unable to seal between the parts. The cylinders will warp and not allow for the pistons to properly move nor for the rings to keep the combustion chamber separate from the oil, which is now mixed with any coolant left in the system. Narrow clearance areas like bearings also warp and now provide much more resistance. I'm sure I left some out, but also the main forms can outright crack. Metal against metal needs lubrication. Things like main bearings and rod bearings are simply metal separating two other metals. In short it's not worth rebuilding versus new equipment and sometimes not even possible at all.",
"Inside an engine there are pistons that reciprocate (move up and down) within a cylinder. Due to the large amount of heat produced by engines from combustion and rapid movement of the piston inside the cylinder, engines must use a lubricant such as engine oil in order to stop the pistons from essentially melting to the cylinder walls. There are two types of engines, 4 strokes and 2 strokes. While both use oil as a lubrication, 4 stroke engines store oil inside what's known as the crank case near the bottom of the engine. Oil is essentially shot into the cylinder from the crank case while the piston is moving up and down in order to lubricate the cylinder and allow the piston to move freely with very little friction. The oil then drains back down into the crankcase and is reused. 2 Stroke engines work very similar but rather than storing the oil inside the engine, the oil is usually mixed together with the gasoline. When the fuel valve opens, the engine is not only receiving gasoline for combustion, but also a portion of oil mixed within the gasoline to lubricate the cylinder. The excess oil is burned off during combustion. For both engines, oil is a necessity. Without it, the pistons won't move for very long before they become stuck inside the cylinder or what's known as becoming seized. This renders the engine useless. Generally, the engine is destroyed if it becomes seized as parts become almost welded together inside or break apart. In rare cases, the engine may be salvageable if it wasn't run completely dry of oil or the engine was shut off before it fully seized. However, this almost always results in scoring on the inside of the cylinder and piston. When scoring occurs, the piston no moves as fluently reducing power and oil can begin to leak between the scars inside the cylinder. This is fixable though, usually with a replacement piston and boring out the cylinder to a slightly larger size to get rid of the scarring inside the cylinder. This becomes more of a hassle the more cylinders you have. Jesus, I think I made this too long to actually be of any use lol. Anyways, in conclusion, don't run an engine without oil or it will seize and become useless. The Germans, or anyone for that matter, would most likely scrap the engine as it would not be worth the time or cost to try to repair a seized engine, especially in the middle of a war."
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l8o8pc | How does more energy consumption equate to better tech? | The Kardashev scale posits that more energy harvesting/consumption equates to increasingly better tech. Solar panels alone can easily power the world. Geothermal can easily boost more than is needed. Does seemingly impossible science advancement (e.g., teleportation, replication, weather control) really hinge on the fact that we can’t currently generate enough juice? It seems like it’s a mechanics problem to solve, and less about the fact that we need to have a damn Dyson sphere? We’ve got plenty of energy access, even in 2021. No? | Technology | explainlikeimfive | {
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"The Kardashev scale is a measure of the ability of a society to use technology. We do not have \"plenty of energy\" in 2021. Why don't counties with fresh water shortages desalinate sea water? Because they don't have enough energy. Why don't we use chemical processes to remove the excess CO2 from the atmosphere and reverse climate change? Because we don't have enough energy. We can't do things that we already have the science for because we don't have enough energy that's cheap enough. The SciFi stuff isn't needed to show that the current Earth is energy limited.",
"Would put it the other way round higher tech requires greater energy consumption, so without energy supply the higher tech isn't practical, so mobile phones aren't of any use without somewhere to charge them."
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l8os7t | who are the professionals that use "professional grade" products? | For example: knives, power tools, kitchen equipment... Many of them are marketed as being quality because professionals use them. Do they go to professionals and ask them to endorse their equipment? Are there "professional grade" standards they have to meet? Or is it mostly just a vague marketing ploy that doesn't actually mean anything? | Technology | explainlikeimfive | {
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"“Professional grade” or “military grade” have literally no meaning. None. It’s just completely made up marketing terms to appeal to schmucks to make them think they are getting high quality products. Literally no meaning.",
"It's almost all marketing. Actual professional stuff is rarely advertised to normal people. And sure, there are standards, but they're not in any way uniform. It's not like there's any organization out there deciding what exactly qualifies as a \"Pro\" hard disk. It changes over time anyway. In general, if you're a professional you understand the subject matter well enough to know what kind of specs you need. So for instance if you are looking to store some data you have some particular requirements regarding to size, IOPS, GB/s and write endurance. You're not looking for a \"Pro\" sticker, but something with the right specs that fits in your budget. It's up to you to understand what you need and what parts satisfy your needs. Because both the scenarios of \"I need to store a whole lot of stuff, but it doesn't need to be fast\", and \"I need it to be extremely fast\" are possible. It's then your job to pick the right tool for your particular job. And of course in any given field you'll get different characteristics. For a CNC mill you can get all sorts of stats about how precise it is, how fast it can move, what size of tooling it accepts... again up to you to understand all of that and determine whether that machine is suitable for your job. And depending on how big of a deal it is you may have a contract with your vendor where they agree that if this thing breaks, they'll ship replacements by next morning, or give you a lot of money as a penalty.",
"Normally it’s a meaningless term. However, go into a restaurant supply store and check out for example mixers. You won’t see fancy designs, but they’ll be big and heavy with high torque motors that and designed to mix many batches of dough every day without breaking down. It’s all metal with all metal gears, compared to a cheap home mixer which may have plastic gears that would break under the stress. But most of the time it’s just used to sell stuff, not better than anything else."
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l8q0ft | Whats so wrong with break and continue statements? (PROGRAMMING) | I've met several people who hate break and continue statements with all their hearts and souls. Why? What's wrong with them? I understand with goto statements, but what is wrong with break and continue statements? I honestly don't see any issues with them. | Technology | explainlikeimfive | {
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"Wasn't aware people hated these. Have to do a lot of programming for my job and I use them all the time",
"For and while loops have conditional checks built into them. You should be able to structure your code in a way that makes break statements unnecessary. If you find yourself needing them to escape a loop, you aren’t designing your code very well",
"Ideally your code should be constructed such that you should never be `break`ing or `continue`ing because use those statements create a discontinuity in order-of-reading vs. order-of-instruction. I.e. while it may not matter a Goddamn to the computer that you're using `break`/`continue`, to whoever has to read (or worse, edit) your code it can make for a tedious and/or confusing parse. Also, in the context of education/academia, using `break`/`continue` might obviate the lessons being taught. (The most important lesson in this case being that \"you should always write to spec\", because being out-of-spec is how you become out-of-a-job.)"
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l8rgkm | How do Scratch Removing creams work? | I don't understand how a cream can remove physical abrasions on a lens or disc. | Technology | explainlikeimfive | {
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"They are abrasive. The cream acts as a very fine grit wet sandpaper to smooth the entire surface."
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l8vnk3 | Why do videos or images in 4K still look more crisp than 1080p, on a 1080p display ? | Technology | explainlikeimfive | {
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"4k content is generally encoded at very high bitrates, and the media it's stored on support higher bitrates in their specifications. Downsampling a very high quality image can achieve better quality than just displaying an initially lower quality/resolution image at it's native resolution.",
"If you want the super simplified explanation it's because of the fact that when you record something, regardless of resolution on most devices, your phone/camera will throw some information about each pixel's color away to save space. Since a 4k image has 4x the number of pixels than a 1080p panel, each pixel on the 1080p is displayed by combining information from 4 pixels in the native image, which leads to a better looking image. Below is more technical breakdown of why this is true. Most cameras today record video by giving each pixel a Y, Cb and Cr value. Y is for pixel brightness, Cb is how blue the pixel should be, and Cr is how red should the pixel should be. If your record and image storing all of these for every single pixel, this is what's know as 4:4:4 subsampling. When I said that devices throw information away, generally the way devices do this is to only store all pixel Y values, but only the Cb and Cr values for 1 pixel and share it with 3 neighboring pixels. This is called 4:2:0 subsampling and it was necessary in the early days of computing to make file sizes reasonable and transfers possible while still maintaining a decent amount of image quality. So when you record something at 4k, then view it on a 1080 display you know have created a situation where each pixel on the display is now made up of 4 subpixels in the 4k image. Even though you only recorded color information for 1/4 pixels in the 4k file, since you only have to pick 1/4 pixels from that 4k file you are now viewing a 1080p image with Y, Cb and Cr info for every single pixel instead of normal 1080p file that only had that info for 1/4 pixels."
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l91ufm | how do TVs and other screens create the image? | Technology | explainlikeimfive | {
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"The slow mo guys did a fantastic video on this topic. You get to watch a crt draw an image line by line, for instance. URL_0",
"The signal received by your tv tells it to draw an image 1 pixel at a time, left to right, top to bottom. It just does this so fast that you can't see it happening, so TV isn't actually smooth motion it's a series of still pictures drawn at very high speed. A TV that operates at 60hz means that it draws 60 frames per second. The screen resolution is how many pixels are on the screen. So 1024 x 768 means 1024 pixels wide, and 768 tall. A pixel will be drawn a specific color, and that color info (in digital at least) is just a series of numbers representing the strength of the 3 primary colors RGB (Red Green Blue). Each color is represented by 8-bits (8x 1's and 0's) meaning that each pixel requires 24 bits of information. Each digital channel is streamed live at 19.39-megabit-per-second (Mbps) The signal is actually the black and white information for your TV first, and the color second. This is a hold over for when TV were originally in black and white and they needed to add the color information while being reverse compatible. I believe modern digital TV signals has finally been done away with this. LCD screens draw images the same way as old tube TVs, one pixel at a time left to right, top to bottom, but use digital cells to draw color instead of a Cathode Ray tube shooting electrons at the screen.",
"/u/DarkAlman explains the mechanisms well, here is the other end of the story. Humans aren't good at seeing **fast** things. So our brains \"cheat\" a bit, in a way known as \"persistence of vision\". As a super simple example, picture a flaming ball at the end of a short rope at night. A fancy dressed pacific islander then spins that ball at the end of the rope quickly. Your eyes and processing are not fast enough to keep \"seeing\" the flaming ball. Instead your brain says \"its now a flaming **circle**\". Other similar examples might be toys or novelty fans with LEDs that spin quickly. By blinking the LEDs on and off messages and moving pictures can be displayed. Interestingly, the proto-TVs (like way before your grandparents) used spinning discs with holes cut in them for light to shine through (they didn't have very good lightbulbs, much less LEDs). [Here]( URL_0 ) is the first in a playlist that might help if you have further questions."
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l92jgp | How is it that such tiny cards can hold gigabytes of data? | Like, physically, how does storage work? How is it that 60 years ago people built massive units for a couple megabytes of space and now you can save gigabytes of data to little cards? Thank you in advance! | Technology | explainlikeimfive | {
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"One thing people are omitting is the complexity of the design of an SD card or similar flash media. A compact flash disk is much smaller than a hard disk drive because its sole purpose is simply to store information, but a hard disk has to do other things like cache data, spin to retrieve information, and have smart error correction and detection systems. Think of this like storing information on a piece of paper - you can stack a huge amount of paper and it will not take up much space, it's cheap and effective since all you care about is stacking paper with data on it. But if you want to organise it and make it more efficient, you need things like a filing cabinet, which now take up much more physical space. You can store more information on a piece of paper by making the font on the print smaller, which is kinda-sorta like how reducing the size of transistors works so you can therefore use fewer pieces of paper to store data.",
"So, to answer the physical question, which is the real question, we didn't have a great understanding of materials and how electrons could pass through different mediums in the before times. We started with literal punch cards. Pieces of paper, that we could look at and count by hand and literally translate into 00, 01, 10, 11. On or off, pure logic. It is, or it isn't. Pure, simple math. We already knew the outcome; we fed it into the reader and it produced what we wanted. Then it was a matter of reversing the process; ask a math question, and it would produce a punch card that we could then translate into a number. So that's the physical point we started at. We scaled up from there to a variety of things. We used old school tech like vinyl records which had grooves at specific points creating a 'up' or 'down', or magnetic tape, all corresponding to either a 'positive' (not atomically) or a 'negative' (still not atomically). Anything can be a positive or negative. +5 volts can be a positive when measured against a 0 volt base. +10 oranges is still +5 if 5 is your base, the point is that it doesn't matter the value, its just a reference point. 5 microvolts on a transistor is still higher than 0 if that's the baseline. So we have established a high versus low relationship. So we went from paper to rolls of tape. Then we figured out transistors, which is an entirely different ELI5 thread. Transistors can be made incredibly small. Because physics, one side can amplify a signal while another side stays grounded. So you have three legs, an input, a base, and an output. As long as you know your base, you can send an input and you will know if you have a 'high' or a 'low'. Because we have some very precise machinery and can grow very cool, precise crystals, we can decide which things make highs and lows. If we make different layers of these crystals, we can create the same punch cards from above, just super tiny, because we can control where the holes are. On an atomic scale, we know where the holes are, and by applying the proper voltage can fill those holes with electrons, or not, and thereby create the same on or off condition. You can still think of it as a stack of paper punch cards, just really, really, really small. Here is a good picture with a good write up: [ URL_1 ]( URL_0 ). Edit: I don't have kids, but in the interest of ELI5, if I did have one, I would expect them to say \"But how do we make the punch cards so small\" and I would say \"vapor deposition. Eat your chicken nuggets. It's almost bedtime\"",
"increase precision of machines in manufacturing, build new machines for manufacturing with increased precision and discard the old ones. Repeat. and sprinkle some new tech here and there.",
"i'll just explain flash drives. One FlipFlop switch hold one bit. 8 holds one byte aso. is made with lets say 5 transistors. building one transistor was hard a few years ago but now u can build these fckers on an atomic level. Its kinda like lasagne. u have these diffrent layers of some metals and when it all come together they become a transistor"
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l934z8 | Why do screens have a maximum refresh rate they can't pass? | Technology | explainlikeimfive | {
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"Let's start with what the refresh rate is... So, when tvs were first invented, there was basically an electron gun behind the screen that shot one pixel at a time. Left to right, top to bottom. How many times it could shoot up the entire screen in a second is how we define refresh rate. Tvs today still follow that same pattern. One pixel at a time, left to right, top to bottom. We're also dealing with a lot more pixels. For comparison, the first tv only had 60 horizontal lines. HD tvs have 1,080 horizontal lines, 4K tvs have 2,160 lines. And it's worth noting that each pixel has to receive two kinds of data - what color it's supposed to be, and how bright. Refresh rates have also gone up. The original tv broadcast standard (in the U.S.) was 30fps. We now commonly deal with 60fps or 120fps. (59.94 for any sticklers that may be reading this.) So long story short, there's a lot of data and a lot of processing going on under the hood to make a monitor work. And some monitors have more processing power than others."
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l93fp4 | How data travels from a server to user's computer. | Technology | explainlikeimfive | {
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"Fiber Optic and copper cabling. And tons of network routers and switches. Your computer will request data from the server. That request travels through the wiring in your house (or cellular) and then gets to the next piece of equipment. It keeps doing this across the country to where the server is. The server responds, and it takes the same route."
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l94zfi | What is the difference between Verizon's 5g Nationwide and 5g Ultra Wideband? | Is it worth the extra $10 | Technology | explainlikeimfive | {
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"/u/bluebirdgm is underselling it. “5G Nationwide” is Verizon’s brand name for 5G service on frequencies under 6GHz. This service is very similar to standard 4G-LTE, and it will provide similar speeds and coverage throughout the country. Expect download speeds around 120Mbps. “5G Ultra Wideband” is Verizon’s brand name for so-called “millimeter-wave” 5G. This service is provided at a *much* higher frequency. It provides *massively* faster speeds–up to 1.5Gbps–but the signal is *extremely* finicky, requiring a direct line of sight to the tower, and 5GUW towers are located in *very* limited areas, usually in large cities. 5GUW usage on Verizon is free, meaning it does not add to your Premium Data usage. If you live in a large city, I’d say it’s worth it to get 5GUW access."
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l96vxr | Do televisions also use AM or FM? What do they use and what are VHF and UHF? | Technology | explainlikeimfive | {
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"VHF - Very high frequency channels 2-13 UHF - Ultra high frequency channels 14-69 The entire FM band for radio is between channel 6 and 7 on the tv dial. Sometimes if you dial your car radio down enough (88.3 - 88.7) you can listen to tv if you have a channel 6 near by.",
"Both. For antenna TV (which I assume you are refering to) they use amplitude modulation (AM) for the picture, and frequency modulation (FM) for the sound. VHF means \"very high frequency\" and refers to radio frequencies between 30 and 300 megahertz (MHz). UHF means \"Ultra high frequency\" and refers to radio frequencies between 300 MHz and 3 gigahertz (GHz)."
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l9eynb | How do radio microphones sound so ''deep''? | I was listening to a radiostation with a livestream on YouTube and the voices of the presenters we're incredibly deep. The guy that hosts the radioshow also has a TV show and there his voice is much more ''normal'' as to where he's on the radio his voice has a lot more ''oompf'' to it. | Technology | explainlikeimfive | {
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"The microphones used in professional studios are of high quality, but the typical radio sound has more to do with dynamic range compression and the proximity effect. What compression does is it takes a signal and makes the softer parts louder, while simultaneously making the louder parts quieter: it compresses the dynamic range. This makes it possible to make the signal as a whole louder, because the loudest parts (eg. plosives) are automatically turned down so they don't distort. The whole speech sound then seems beefier, fuller and louder. Compression is used a LOT in music production as well. Also, in radio and podcasts it's usually possible (and deisrable) to have the microphone very close to the mouth of the speaker, while on TV it would not look good to have huge microphones in the faces of the guests and presenters. The benefits of having the microphone close is improved signal to noise ratio, the microphone picks up the voice nice and strong without picking much noise from elsewhere in the room. However, microphones tend to have what's known as the proximity effect, where the microphone picks up more low frequencies the closer to the sound source it is. This also adds to the depth and fullness of radio voices."
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l9gnmp | Why is Open Source Software considered safe if it can be accessed and changed by anyone? | Technology | explainlikeimfive | {
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"I have a piece of closed-source software that's super secure. Trust me, it really is. I'm not going to show you the code, but I pinky-swear promise it's secure. I have a piece of open-source software that's super secure. Go ahead and look at the code yourself if you want proof.",
"It's not quite like wikipedia where anyone can change it. Anyone can write some changes and offer it up to the project owners for them to look over and decide whether or not to integrate the changes. Anonymous people can't just change the software on a whim.",
"It is intrinsically safe by virtue of being fully open. A person with an understanding of the programming language used can see exactly what it is doing. But then we come to the issue of any one being able to change it, and you're right. That's why you should only download from a trusted (original) source. They may also provide a hash or something that proves the compiled program you downloaded is the official unaltered version.",
"In no sense is open source software free of bugs or safe. There are plenty of people looking at it, but cleaver evildoers are very hard to detect. There was a security defect in OpenSSL for a decade before it was detected. No software is safe, unless you wrote it yourself and wrote the compiler that compiled it yourself and wrote the operating system that runs it yourself and didn't make any mistakes. This means no software is safe.",
"Anyone can see it, but it's not like just anyone can change it without permission. Part of why it's considered safer is because you can be sure that nobody's sneaking in things they didn't tell you about since you (or someone you trust to know what they're talking about) can go look at the code, which you can't usually do with pre-compiled programs.",
"People can see everything that people are trying to add to it, and they can object if they see something that doesn't look right. With closed source software, the public users have no idea what's going into it or how the company is reviewing changes. I would not say that open source software is automatically safe, but popular open source software is probably saf*er*.",
"\"Open Source\" isn't a monolith: Each project is run differently and has different requirements for contribution. All changes on the main branch of an open source project or piece of software must meet the contribution requirements, so in general the group of people who manage the project have oversight and will only accept changes that they want, which means that if you trust the person or group of people that manage the project you can (generally) trust the project and resulting software as well.",
"If in distributing an open source application which doesn't steal passwords, every one is Alcyone to verify it doesn't, and anyone who got theirs from me won't have their password stolen. Say, you take my app and add code in it which steals people's passwords - if you distribute it as open-source, people will find out that your fork of my app steals passwords, and warn others to get their app from me and not you. Your only good alternative is to distribute your app with the source code closed, and market it to people who don't know better, and don't realize there's a free, open-source alternative. Welcome to the software market."
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l9k4lu | How do they find shortcuts in video games? | Technology | explainlikeimfive | {
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"There are a ton of ways to find shortcuts. Sone were accidents. Some were found while searching for them. Some were found by looking at the games code. Some take a ton of effort from multiple people to figure out how to make it easier or save time with it.",
"> they just bored and accidentally found it Pretty much, this. QA teams who test the games ask developers to put in such \"cheats\" so they can test functionality faster. These teams are then pinky-sworn to secrecy. If the game isn't successful, the team's fired and some members may decide to break their agreements and blab. Source: Am a software developer, was in QA in a previous job."
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l9kdan | How did the ancient civilizations used to make ice? | Technology | explainlikeimfive | {
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"They didn't make ice. Wealthy people would have giant blocks of ice shipped to them from cold areas, keeping it cold by packing it in a lot of wood shavings as insulation. It would get shipped by boat or animal drawn cart. Before that was a feasible thing to have done, only people in cold areas had ice.",
"They didn't. They harvested it from frozen lakes. Then they would store it in a building and cover it with hay or something and hope it lasts all summer.",
"In deserts, at least in North Africa and the Middle East, ice was made by exposing water to the night sky and then keeping it very well insulated during the day. Even if the air temperature didn't dip below freezing, the heat radiating from the water into the cold, black sky would allow it to freeze. This is known to have been done in ancient times, thousands of years ago.",
"They didn’t, they collected it from lakes etc. Generally though ice is not very important for human civilisation. Yes it’s useful for preserving some foods but people are pretty inventive at coming up with other ways to do that.",
"They didnt \"make\" it. They got it from cold places and transported it in big chucks. Like, boulder sized chucks. There was quite an industry in the ice-delivery business. Then they kept the ice in cold places like deep cellars or caves."
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l9nxkx | Why do some phones still have their data even after a factory reset? | This actually happened to me, I had this old phone that had a pattern lock. obviously, I didn't know what was the correct pattern. so I did a factory reset. When the phone booted I saw some pictures despite there was no SD card or anything like that. Why did the files not get erased?? especially on older devices (2010-2013) | Technology | explainlikeimfive | {
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"It probably depends on what the factory reset does. The common things to reset are things like installed programs, settings, and OS state. If the factory reset only cares about those things, then files in the photos folder can easily be ignored. If the entire file system is rebuilt, only then would your photos be at risk of getting lost."
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l9t15f | How does art restoration work? For instance, if I found an old painting somewhere, and took it to a restoration specialist, what is it that they actually do to the painting? | Technology | explainlikeimfive | {
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"Any video from this channel does a hypnotically calming job at showing you how art gets restored and conserved. Even in ASMR. URL_0",
"In general, they remove once-airborne particles and fluids. Smoke, soot, dust, dirt, oils, and some contaminants from packaging and transport are common. As far as the process, it’s generally a fine line between brushes/solvents that remove things they don’t want to keep vs things they do. Beyond that, AFAIK it depends on the medium, but I could be wrong.",
"There are actually great videos on YouTube about this. I've watched countless hours of this guy restoring paintings. I absolutely loved it. URL_0 he actually explains the process and why he chooses the instruments and substances he uses."
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l9uhsk | How do mass distilleries keep the methanol out of their bottles? | Thanks all for the answers | Technology | explainlikeimfive | {
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"There isn't very much methanol produced in large distilleries. However, when distilling the beer to make whisky (for example), the liquid goes through a still. This evaporates off the alcohol, and condenses it, collecting the higher-proof liquid. The methanol evaporates off first. So, distilleries will run off the initial part of the liquid that condenses and not collect it, only beginning collection once things settle. This part that gets discarded is called the foreshot.",
"While the methanol produced in the first place is minimized, the process of distillation also removes methanol. In the fractional distillation process, methanol should be one of the first components to come over, and will do so around 64.7 degrees celcius."
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l9wgb6 | What is the technological singularity and superintelligence? | Technology | explainlikeimfive | {
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"Imagine a \"thing-inventor\". This thing-inventor is able to invent things. One of these things is another thing-inventor, a little bit better than the original. It can also invent thing-inventors. As you go along this chain, you get an ever increasing level of complexity and power. This spirals out, until there is no improvements to be made. That's the technological singularity.",
"They call it The Singularity because it's like the one in a black hole: it's the point we can't see past. Once AI is sufficiently advanced to iterate and design on its own, we have no idea what happens next. All our predictions and models are based upon ourselves, nobody knows what true AI will be or do."
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l9wmcv | pc water cooling | How does pc water cooling work? Also, wouldn't it just short circuit the pc? | Technology | explainlikeimfive | {
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"All the components are isolated from the water, they transfer heat to metal heat spreaders, which immediately transfer it to a sealed closed loop of water.",
"The entire system is enclosed, the portion that goes from either the CPU or GPU doesn’t have water come into contact with the things they cool those transfer heat thru thermal paste (special compound that has great heat absorption and transfer properties) from the part thru the thermal paste to the metal surface which then has the back of it actually a whole bunch of little metal fins that look like window blinds right? Those are called micro fins and yes they are tiny and have a shit ton of em so water or whatever type of coolant you use can get in between them all and pull heat. The water or whatever is actually running across that Being pushed out the other line through the radiator there’s all those other friends to dissipate heat across them so by the time the water comes back down and makes a complete cycle through it’s cool that it’s constantly moving heat away from these parts.Theoretically could definitely short circuit a PC if it’s not properly sealed however in theory I could also take my entire computer put it within a bathtub full of water take it back out and just not plug it in until I am absolutely sure there’s absolutely no moisture anywhere then edit and it could also theoretically work my hard drives might be fucked but it might work thats only a major concern if you have a leak. You’ll know if you have a leak very quickly if you do a custom loop which is where you create all your own piping by cutting and bending the tubes the way you want it or you have whats called an AIO Which stands for all in one that’s a close system sold by major retailers that you literally just plug and play with basically there’s anti-growth within the line to prevent microbes and bacteria and what not from growing and it’s sealed so you never change the water there have been cases where those eventually start leaking but it’s extremely rare. Water cooling well there’s the argument it is better for temperatures which gives you to theoretically better performance and also drastically depends what you’re doing with the computer and there’s typically only a big computer enthusiast investment because it can be quite expensive but it is dope air cooling is perfectly fine for most people however. I have an AIO. PSA: if you think water cooling or improving your PC Temps in anyway will make your room or play space cooler since you pc is running cooler you are wrong. It will make the area hotter if its in say your bed room bc your pc is even better at dissipating heat and will make your room a swear lodge at times like summer."
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la1rt3 | how did the editing of shows and movies happen during the early days of television? | i really love silent films and early technology, it’s amazing to see where we started. i got my mother into the twilight zone, and we’re watching it right now. when watching the opening sequence, there’s things like tvs and glass smashing over top the night sky background, and the blinking eye. i was about to make fun of it but then i tried to imagine how tf editing software would even work, so i assume they didn’t have any. BUT IF THEY DID I REALLY GOTTA KNOW. or did they just literally lay films on top of each other? i have no idea | Technology | explainlikeimfive | {
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"Early special effects were really amazing. There was the cutting and splicing to edit film, and that was every movie made. If you've heard the expression \"left on the cutting room floor,\" that's when a scene was literally cut out and then not placed back in anywhere. Filmmakers would use small props, they'd use tricks of focusing, they'd draw onto the film, so many creative ideas. It's a good topic for some research if it interests you.",
"Those Twilight Zone effects are mostly done with non-digital compositing techniques, using [optical printers]( URL_0 ), mattes, and [rear projection]( URL_2 ). > or did they just literally lay films on top of each other? One technique did exactly that. 'Bipacking' involved using cameras that could feed two reels of film simultaneously. One reel would already contain footage, which had been shot with part of the image blacked out by the physical equivalent of a Photoshop layer mask. The other would be unused. As you filmed, the two reels would touch each other and the image from the used film would 'contact print' onto the new film, overlaying it onto the scene you were filming. I remember that there are some episodes that use the really cool and really retro techniques like [Schüfftanning]( URL_1 ) too, where it's all about precisely placing mirrors and miniatures. Silent movies used mirrors in a lot of clever ways that overlapped with stage magic techniques."
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la282s | What is the reason for the sound of an app still playing, despite the actual app being closed? For instance, if I close my Spotify app sometimes the music will still play a few seconds afterwards. | Technology | explainlikeimfive | {
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"The music file or a portion of it that is to play next is already buffered in the device’s memory, this buffered segment of the music or sound is set to play through the device audio circuits as soon as the current bit is done. Once you close the app, no further sections of sound are sent to memory, so the sound stops as soon as the memory location is empty."
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la3bme | Why is call hold music always so distorted? | Technology | explainlikeimfive | {
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"text": [
"The telephone system is designed for carrying human voices. It has very limited bandwidth, so we actually add compression onto it as well. This is why someone doesn't sound the same on the phone as they do in person. The compression that we do for human voices makes music sound even worse. This is because music has a much bigger range of possible sounds than the human voice, so the compression takes it even further away from its original sound.",
"The frequencies used in telecom are optimized for the specific frequency range of the human voice. Music often encompasses a wide variety of frequencies, so it has to be crushed and compressed into a narrower frequency range in order to be transmitted over the phone. The effect is like trying to listen to an orchestra through a pipe."
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la3hck | why is it that if we leave a battery overcharging it starts losing its charge-retention capacity? For example in laptops or phones. | Technology | explainlikeimfive | {
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"Overcharging isn't really a thing anymore since modern gadgets are smart enough to stop charging when a battery is full. They then bounce between 95-100%, discharging and charging as necessary. (Maybe not exactly, but roughly) But this still introduces wear since the battery is still providing and receiving energy. Lithium ion batteries also don't like to stay at the extreme ends of their capacity. (fully discharged or fully charged - I don't have an explanation to that at this time, I saw you asked in another comment) To help preserve life you sometimes get the feature to keep the maximum charge at 80% (again, this number can vary but it's a default) to reduce long-term wear. This is why the iPhone can learn your routine and charge up to 80%, wait, and then complete the charge when it's closer to when you wake up to reduce time at 100%. My laptop, some Android phones also have that feature but how it's accessed can vary widely.",
"It doesn't. That quirk only applies to Ni-MH batteries. Li-ion does NOT do that. It, however, wears out with recharge cycles, so you can only get so many (~1000) 0-100-0% cycles out of it before it can't keep charge anymore. In Ni-MH it's apparently crystals forming inside and inhibiting the movement of ions as a result of repeated overcharging."
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la9fnx | What is RAM and why is it important for browsers? | Technology | explainlikeimfive | {
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"RAM or random access memory, is the memory used by programs and the operating system to handle work. This is very fast memory that allows the programs to read and write to it very quickly and not lagging and buffering. Picture the countertop on your kitchen. If you have MORE countertop space, you can lay out all your ingredients, recipes, and equipment to prepare a large meal. This allows you to perform efficiently. Now picture a tiny kitchen in a submarine. You only have enough space to handle one task at a time, you have to now prioritize what to work on with the space you have. This greatly slows down your ability to make a large meal, and possibly prevents you from making the large meal altogether.",
"RAM is pretty much the ability to store information so it can be instantly recalled rather than loading. So if you visit a website like reddit over and over it can just go to that spot in the ram, put it where it belongs, and go on to loading other stuff. The more you have, the more you can store to instantly recall."
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lac869 | How do microcontrollers understand/read code? | Technology | explainlikeimfive | {
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"The different modules in the processor is controlled by control signals. These are single wire signals that can either be on or off as set by the control logic. For example an adder might have control logic to activate it, select between a handful of inputs, set the initial carry bit, activate the output, etc. A register have control signals to set it, clear it and activate its output. A muxer will be used to select input based on the control signal. And so on. So in order to control a processor you need to set these hundreds of control signal to the correct value so the processor does as the instructions say. The simplest way to do this is with a simple lookup table. For each instructions and each sub-instruction cycle you program into the table what exactly the control signals should be. The hardware will then be able to use the current instruction and the sub-instruction counter to look up in a ROM to find out what the control signals should say. The control signals will also read inn the next instruction and reset the sub-instruction counter when the instruction is done executing. Note that this is how they would do it in the 70s. Modern processors are far more complex but the basic principle of setting the control signal to its correct value using some sort of fixed logic is still the way it is done. However modern logic is less fixed and your processor might receive microcode update which change this part of the processor.",
"There are a few ways to answer this question because your question is really a bit general: 1) Microcontrollers don't understand/read code. They operate on a series of on/off signals provided to their pins as they propagate through the internal logic circuits (usually timed through a clock signal). It is a very sophisticated state machine. This is kind of at the level of an electrical engineer who designs the microcontroller. So this is probably not helpful. 2) Microcontrollers are designed to understand binary inputs given to it called machine language or machine code. These are just on/off signals but are often written in hexadecimal numbers so that some (really sad) engineer has to hand code it by referring to the machine language instruction book written for that particular microcontroller. For example: 100A might be the hex code for \"load the signals at the data pins into the accumulator register\". Maybe not so helpful unless you're writing very time sensitive programs/code. 3) Programs are written in some kind of high level language (C++, Python etc). There are programs that will convert this high level language into machine code and there are also programs written that will transfer this machine code into the appropriate memory locations in the microcontroller so that it can then execute the program. In nearly all cases, the microcontroller will have a basic OS already preprogrammed into it. This OS is sort of a \"master program\" that will call the code written and downloaded and have it executed by the microcontroller. All 3 explanations are more or less correct and it depends on what level you are approaching this question. If you are using some kind of microcontroller board like Arduino for the first time, then probably explanation 3 makes the most sense. If you're actually building your own microcontroller based circuit, then explanation 2 is relevant. If you're planning to design your own microcontroller, then explanation 1 is most relevant."
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laf4cp | What's the difference in hardware between a gaming console and a PC? | Moreover, how is a console cheaper than a PC with comparable performance? | Technology | explainlikeimfive | {
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"The answer would depend on the game console and the PC build you are comparing. Generally speaking, game consoles are cheaper because they have less internal hardware and less expensive components than that of a PC, additionally, Microsoft (XBox) and Sony (Playstation) tend to cut out unnecessary components or find less expensive alternatives. Most PC have more internal components and better grade components. For example, Sony usually has their own proprietary graphics card for their PlayStation while someone who is building their own PC and spend $1000 for the best graphics card on the market.",
"So first of all a motherboard manufacturer has to have a bunch of expansion slots for more RAM, expansions cards, multiple GPUs and tons of USB ports, SATA drives etc. The hardware contents of a game console are fixed and aren't going to change over the lifespan of the device**. That design decision can cut out a lot of stuff on the motherboard which reduces cost and size. Since the GPU and CPU aren't going to change you can mount those right to the mainboard and put a dedicated proprietary cooling mechanism in place - better cooling for cheaper. Lastly, since you're going to be making tens of millions of them your economies of scale for components (either on the motherboard or in the case) is a lot better than any PC manufacturer. Western Digital would rather sell you 8 million of something than 100,000 of something and they'll set the price appropriately to land that sale. ** yeah, rev B might have a better CPU or GPU but itll fit the same socket/pin pattern on the main board. The benefit of consoles to a game developer is that you can custom tweak your game engine a lot to run specific things specifically better on that platform because they're all the same. On PC its a nightmare; on a DX12 card it looks great, but on an older DX11 card it might look terrible. Meanwhile if you develop for one XboxS, it looks fabulous on all of them."
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lafiws | Why can phone providers do nothing to stop robocalls? | Is it a matter of reluctance on their part, because they don't want to lose the revenue from robocallers paying for phone service? Because I cannot believe the alternative scenario, which is that it just can't be done even if the providers wanted to. Is it really that much of a technological impossibility to find the individual, group, etc. that is sending out the calls and block them at the source (to say nothing of shutting down their operations)? Are we seriously supposed to accept that in 2021 something like this is completely beyond our capability? Please help me understand. | Technology | explainlikeimfive | {
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"a large part of it is the law. carriers used to be forced by law to connect any dialed call, they had no legal ability to not connect a call. notice that you don't get spam text messages nearly as often. those laws don't apply to SMS, and cell carriers usually hire a 3rd party (my old employer used a very common one, synniverse, who also does SMS interconnect for Verizon and Sprint as well as others) which filters out spam.",
"Simplest explanation: Phones calls used to be made over phone lines. With the advent of VOIP (that is, voice over Internet protocol) calling, every scamming jerk with a script can trick the phone system, because the data is infinitely easier to manipulate at many points during the direction/travelling of the call. As far as being unable to just shut off access to the bad guys, think of it like a monster that grows a new head every time one is cut off.",
"The telephone system as currently built doesn't really have the capability to stop everything. They stop a lot, but not everything. Its fairly trivial for someone (generally abroad in places like South Asia) to get equipment necessary to to do robocalling and get it by all the protection. Phone systems essentially work on a one-way street of trust, the \"caller\" is always trusted, the system doesn't ask them to verify themselves and assumes everything is OK. This allows a nefarious user to do some things like act as if they are calling from a number they aren't and used automated systems to call. In fact though-- the phone companies are working on solving this, just slowly . As part of the next-gen version of the phone system there planned to be some quite robust anti-spam like functions which \"verify\" certain callers as to prevent this type of activity slipping through.",
"By law, the carriers must connect all phone calls. The law was first put in place to prevent anti-competitive behavior, the ol', \"If you wanna talk to your auntie, you're going to have to do it from our phone network!\" The US government needed a reliable and connected nationwide network for times of war or emergency. The carriers are aware calls are coming from VoIP links into the phone system. They know the caller cannot be verified beyond that point and that it's likely spam. Spammers use these systems because they can carry out automated calls at effectively zero cost and they can dodge all the existing anti-spam legislation that exists which assumes an autodialer attached directly to the phone system, meaning such a thing CAN be traced back to them. Back before the internet, that was the only way you could have run a spam service. Up until recently, all they could do is warn you that the call was likely spam, which is displayed on modern smartphones, but, legally, they HAVE TO connect the call, and it has to be you who declines the call. The FCC has ruled very recently that carriers now have the power to mitigate spam calling on their own. The details go off into the weeds. What I expect will happen is that carriers will stop connecting VoIP calls from uplinks that get themselves blacklisted."
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lau53j | What makes a singer's voice sound "old fashioned" when listening to older songs? | For example, at the 1:10 mark, the male chorus sounds so different to me from modern singers: [You Can Fly]( URL_0 ) | Technology | explainlikeimfive | {
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"I would say this is the combination of recording equipment at the time but also the Mid Atlantic English Accent. (The old fashioned movie voice)"
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lav45g | when people use a supercomputer to supercompute things, what exactly are they doing? Do they use special software or is just a faster version of common software? | Also, I don't know if people use it IRL. Only seen it in movies and books and the like. | Technology | explainlikeimfive | {
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"They are mostly fast because of multiple processes at the same time. The do not work well on linear problems and scale best on tasks that can be done in parallel. They have special schedulers that assign calculations to cores and collate the results. Its more like a hundred or thousand PCs all working together on one problem.",
"So my work is in Quantum Chemistry (Supercomputer time is life) and our calculations are essentially linear algebra on a massive scale to calculate tiny particles. Based on how efficient the computer algorithms are these separate linear operations can be run in parallel very quickly. We use a combination of self-built/shareware and proprietary paid-for software designed for use on supercomputers. The biggest optimization that goes into our calculations is figuring out which operations need to occur in order and which can be run in parallel - sadly there has been limited work on figuring out which operations can be ignored (something like 90% for small molecules (5 atoms) and something like 99.99999+% in anything like a protein). For more information there are some good primers on Quantum calculations out there and some really interesting work into how to use Quantum computers to skip a lot of these matrix calculations in interesting ways.",
"It depends. A supercomputer is, roughly speaking, hundreds of smaller computer chained together (with extra hardware like GPU,... sometimes) You have two ways of using that: 1) launch a simple code hundreds of times on individual datasets 2) launch a big special code that uses all the small computers (nodes) at the same time. In case 1, the software is the same as it would be on your computer. In case 2, it's a software specially designed for the supercomputer.",
"They use a lot of (fast) computers combined and that's why it's so much faster than a single one. Imagine 2000 very smart people working on a list of math problems instead of a single person.",
"Supercomputers *that* much faster than a regular computer, it's just that there are lots of separate computers working together. This means the software that is running on them needs to be able to split up the work in a way where multiple things can be run at once, therefore having a performance gain. Take the following todo list: 1. Reply to boss's email 2. pick up child from soccer practice 3. go to grocery store 4. drop child off at friends house In the list above, we could either have one person do all of them sequentially, or if you had two more people to help you (total of three people), then steps #1,# 2, & #3 could be done all at once by different people. Step #4 however, can't be completed until step #2 is done, and also needs to be done by the same person who completed step #2 as they have the child in the car. Computers are the same way. Certain problems can be more easily split up and run in \"parallel,\" while others must rely on the result of a previous step. The same thing is happening in your average computer when you have multiple \"cores.\" Each core can run a different task, but the software has to be able to efficiently split up those tasks in the first place in order to utilize them.",
"Supercomputers are used on very specific types of problems, they need to be massively parallel because we're not talking about using 4 or 8 cores, we're talking around 10,000 multicore CPUs and 20-30k GPUs which gives closer to a million independent cores. Folding@Home is a good example of a distributed supercomputing problem, basically you need to try every combination and you can have each core testing a combination and then moving onto the next Early supercomputers were used for modeling in nuclear weapons. They wanted to model all the little bits and track tons of points in the explosive and core and model how it will all compress together to create the reaction. Stuff like this and Computational Fluid Dynamics are basically infinitely parallel and more cores results in either better results with more points, or much faster results with the same number of points You can't just throw a super computer a Crysis and expect it to play nice, that wasn't the type of problem it was meant to solve",
"A super computer is really just a bunch of computers connected together to work together. Users use special applications to split a workload across them. A normal CPU can only handle a few things at a time and any further work has to wait, albeit nanoseconds, to be processed. With a super computer, you wait less because it's distributed across all the processors. A good example is render farms for 3D animation studios like Pixar. Rendering those movies takes a LONG time, as it has to work hard on each individual frame of the movie. Pixar uses \"super computers\" to divvy up frames to different machines so that it takes less time. Fun fact: it still takes weeks to months to render the whole movie. Source: I work in IT AND do video editing and 3D rendering as a hobby. I've actually set up distributed rendering across multiple PCs at home.",
"Some problems we can give to computers in different ways. Let's say you wanted to find all of the even numbers from 1 to 1,000,000 If you have a simple processor that can do one operation per cycle you might tell it do do the problem like this 1-Start at 0 2-Add 2 3-Record that number 4- go back to step 2 This single operation processor will need to repeat this 500,000 times to finish. That could take a while Or you could build a really big computer with 500,000 simple processors You can then approach the problem diffently Give each individual processor a number from 1 to 500,000 and these instructions 1-start at the number you are given 2- multiply it by 2 3- record that number Our big super computer can now solve the same problem in one go. So some of super computing is writing the program smartly so it uses many processors well, but most of it just throwing a ton of processing power at the problem all at once.",
"Supercomputers are machines with a large number of processors and lots of memory. They tend to use basically the same software everyone else uses (generally free and you could download it and run it on your computer). There are a couple of kinds of problems: those that are parallelizeable and those that are not. Parallelization is the act of dividing a task up so that multiple, separate entities can work on the task with minimal cross-communication. * Ex of a parallelizeable problem: (borrowed from another comment) if you have a problem set of 100 problems. None of the answers depend on one another so you can find 100 people and make them all do one problem and be done in under 5 minutes. In the real world, this could be a chemistry simulation where you model molecules and forces between them. In a large simulation, you just divide up the simulation space (picture a box with molecules in it) into smaller boxes and let each cpu handle its own box. There has to be a little bit of communication between boxes, but not too much, so this sort of simulation is run on supercomputers. * something that doesn’t parallelize well: imagine solving a long division problem to a million digits. Even if there’s 100 people around you willing to help, it’s a hard problem because each step of the long division determines what the next step will be. It’s not possible to let anyone else help with “other parts of the problem.” Therefore, problems that can’t be helped using parallelization don’t scale well on super computers because there’s nothing gained by having more processors. “People” - many researchers, professionals use it. It’s used in a number of areas in research to simulate chemical reactions/processes, in mechanical engineering to simulate loads (ie simulate a car crash), and in NASA for orbital simulation (the Martian bugged me on this because there’s no good reason to be physically plugged into a super computer. The hard part isn’t moving the data to the computer, but actually running the simulation to predict what will happen)",
"Traditional 'supercomputers' such as the Cray ([ URL_0 ]( URL_0 )) usually ran custom operating systems, usually based on a Unix kernal, and so could run most Unix software. These supercomputers were often used in science and engineering in order to process large data sets. So, they might run mathematical models to calculate traffic patterns in major cities so they can optimise stop lights, handle complex stock market calculations or calculate orbital trajectories for space probes, or calculate complex scientific research problems. Their uses were far and wide. However, the pale in comparison to even modern smart phones these days, most of which are more powerful than the classic supercomputers ever were. The actual software applications are often custom written for these purposes - it's not like they were running Microsoft Word or Adobe Photoshop for example. And whilst that software was usually build on for Unix based system, in theory it could run on most other Unix operating systems. However, the key difference is that traditional supercomputers were essentially huge multi-processor systems, and so the software was written to take advantage of that by running processes and tasks concurrently. So, if they had a task to process a million pieces of data in order, the software will break it up according to the number of processors available and feed a chunk of data to each processor, then 'glue' the results back together. If you've got 100 processors who can all work on something at the same time, that's 100x faster than a single processor processing all the data (not strictly accurate, it's not actually 100x faster, but for ELI5, it is!). This kind of optimisation is still present today in regular domestic computers. Some computers can have 8, 10, 12 or more 'cores', but if software is not built to take advantage of all of those cores, those computers can often be slower than single 'core' machines which a faster 'clock' speed. Lots of supercomputers have made way for networked and distributed computing now, just because it's often cheaper to use lots of smaller computers working together than one huge expensive computer with multiple processors, which is why the traditional supercomputers such as Cray's are much less common these days."
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lavbs5 | What is an Operating System? | Technology | explainlikeimfive | {
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"It’s software that creates a standard interface for other software to control the underlying hardware. Think of how cars work. Every car has a steering wheel, gas and brake petal and so on. But you can have a high performance engine underneath the hood. An operating system is like everything between the steering wheel and the actual engine that makes the car go. And cars are designed in a way that you don’t need to relearn how to drive a car when you get a new one. It’s still just a steering wheel and a gas petal.",
"It's basically a software that allows people to run other software on top of it easily. Android is the operating system. It's main job is to run your apps. Sure you can build an app that directly runs without the Operating system, but you're using that phone/computer only for that app. An operating system allows you to run multiple apps simultaneously. It also gives the developer of the app a lot of things easily. If I have to make a Whatsapp clone that shows the messages, connects to Internet to send messages etc. I can use a several modules that are provided by the Operating System to build it. If you remove the operating system, I will have to write all of that on my own.",
"If all of the software on a computer were the workers at a building site, the operating system would be the foreman. The operating system loads up while booting, and then interacts with the user (you). If you ask the operating system to do something (open a spreadsheet, for example) then the operating system's job is to go an open that spreadsheet; to ensure that that spreadsheet has what it needs to do its work (such as, for example, CPU time or the ability to talk over the network) - the spreadsheet gets nothing that the operating system doesn't let it have. If you're running multiple programs at once (say, a spreadsheet and a word processor) then the operating system is what juggles them, makes sure that they each get a fair distribution of CPU time, and basically does all the underlying management. It gives the other programs what they need to work, and it makes sure that they're properly organised. But it doesn't do the work itself. Hence, the foreman.",
"Other answers here are great, but if you think this stuff is cool, I can elaborate a little on how an OS works. An OS is the main program running on a computer and is also the manager of the computer's resources and it's schedule. When another program starts to run, the OS has to approve of it. Sometimes the OS asks the user to put in an administrator password to give user approval, if the OS thinks the program is doing something that the user should be approving manually. If approval is given, the OS will set up an environment for the program to run in. It gets a share of memory space and a timeshare of CPU usage. The OS often has the CPU switching back and forth between many processes. It happens so fast that usually the user can't tell. But if you open many programs at the same time, you might see some lag as the CPU is split between too many things and can't run them all at full speed anymore. Most OS nowadays have a GUI (graphical user interface) that allow users to use a mouse to click on stuff and open visual menus. However, very old OS such as DOS only had a console to type commands in. So the GUI is really just a great feature, it isn't what makes an OS an OS. The management of resources of a machine is what makes it an OS."
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lazqez | Why does it feel like batteries of electronic devices (phones, laptops, etc.) generally last a bit longer at lower percentages? | It always seems like my phone's battery interface goes from 50% to 40% way quicker than from 10% to shutting down, even when I shut off applications that save battery life. Is this a real phenomenon in most phones, or am I just imagining it? | Technology | explainlikeimfive | {
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"I would say due to app usage on your phone probably? There’s really nothing in a battery’s chemistry that would cause a longer life at that percentage as the battery would hold a charge evenly due to the way it’s made. Batteries are basically metal and acid in a pouch. Somehow it holds power. I used to sell the things and still think they’re part black magic, but I digress. Usually when the battery percentage on a phone gets low (~20%) you’ll receive a prompt telling you. At that point the phone will already try and shut background stuff off or put it on pause to try and keep the phone alive long enough to get to a charger, stuff like location services, open apps, internet connections for stock apps, time, etc. It then goes a step further when you hit 10%, so on, so you’ll see an ‘increase’ in use time when it’s on a lower battery just cause the phone’s literally not using as much power anymore. Also, strong to fair chance you’re paying more attention to the phone at lower power than at 50%. Try timing how long it takes to drop the batt % on it sometime, might be a cool experiment to see if you’re on to something. TL;DR: Either your phone’s turning stuff off on you, you’re imagining it, you’re right, or Black Magic. (Experience for knowledge-base: Sold and assembled cell-phones and 100+ types of batteries from button cell to Marine for over 3 years) Edit: corrections, grammar"
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lb0exf | How do updates that require a restart differ from those that don't? | Technology | explainlikeimfive | {
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"Basically the restart is because the files that need to be updated are in use, so cannot be updated. For example, as you have Windows up and running, there are literally 1000's of files that Windows has in an open state because it's using them. If the update you install requires a new version of these files, it can't be done while windows is running. So it requires you to reboot the system so the files can be updated. It would be like trying to change the oil in your car while the engine is running. It can't be done without destroying your engine. You have to turn off the car, change the oil, then turn the car back on."
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lb3ocg | - Why is perfect pitch required to play a theramin properly? | Technology | explainlikeimfive | {
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"It isn’t, it just makes it a LOT easier. A lot of practice can eventually get you thereish. However it should be noted that a theremin is a really strange instrument in how it functions and can be prone to really wacky variations in pitch that you might not see with a normal instrument. Guitars have frets, wind/brass instruments have valves, and even violins and stuff without huge overt indicators aren’t that hard to play mostly correct. I’d probably compare them to something like a trombone which had less defined methods of pitch accuracy. Making sure you’re hitting note changes/intervals correctly is obviously really important. Listening is just as important as watching/the feel of it. In a theremin, you use the position of one of your hands to control the pitch, which is obviously a great avenue for human error. Being able to make corrections on the fly is where having perfect pitch helps.",
"OK, let's take the piano as one extreme. Assume that a piano is perfectly tuned and in good working condition. It'd possible for someone who has no sense of pitch whatsoever to simply learn what keys to press and learn to play a song. As long as you press the right key, you get the right note. Same with a fretted guitar. You can learn fingerings and get the right notes or chords without being able to hear them. Many wind instruments like flute or clarinet are similar. For the most part, as long as you blow in it correctly, and use the correct fingering, the correct note will come out. It doesn't matter whether you can \"hear\" that the pitch is correct or not. However, to play a wind instrument really well, it does require hearing the pitch and making small adjustments. Trumpet and most brass instruments are harder. Playing the correct note requires both fingering and also buzzing your lips with the correct frequency. Beginning trumpet players quite often end up accidentally playing the wrong note even though they're using the correct fingering and think they're buzzing correctly. The only way to know it's wrong is by listening and hearing that it's the wrong pitch, and adjusting. Instruments like violin don't have frets. While you can \"learn\" the finger position for notes, playing well requires making constant tiny adjustments by listening to your pitch and moving your fingers accordingly. Then take singing. You can't sing a melody correctly without being able to hear what pitches you're supposed to be singing. Really, theramin is not that different than violin or singing - you can \"learn\" finger positions for theramin but you can't play them correctly without listening and adjusting. However, \"perfect pitch\" isn't the right term. Perfect pitch just means that if someone asks you to sing or play an F# you can do it without any context. That's not required to play theramin any more than it's required to sing (most singers do not have perfect pitch, though some do).",
"There is no fretting, tuning, or math. You stop moving your hand here or there based on how it sounds you can’t be taught."
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lb5qiw | Why do cable companies still use all that gear when streaming services can offer live TV with just wifi? | I took a job with a cable company doing phone service from home, in my training we had to go over a number of really crappy and convoluted gear that customers will need in order to use the service. I'm wondering why they need all that gear when say YouTube tv offers the same thing without it. | Technology | explainlikeimfive | {
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"First, WiFi is not internet. Its just a convenient way to send a wireless signal a very short distance. The WiFi has to be \"generated\" from a box with a wired connection to the internet. Most people get use WiFi generated by a router, which is physically connected to cable equipment, such as a modem, which is hardwired back into all the buried cable connecting everyone together. Youtube can only get a video to your phone or computer by taking advantage of all the physical hardware and wiring that companies already installed."
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lb632w | Why is audio quality on video calls so terrible? Video can be bad and glitchy but the audio always seems worse even though presumably it is a lower bandwidth signal. | Technology | explainlikeimfive | {
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"I think is has to do with people usually not using good microphones that are close to their mouth. Generally the further the mix is from your mouth, the more noise it picks up along with the intended speech. Most people on video calls are speaking into little pinhole microphones somewhere on their laptop or phone.",
"The human eye isn’t as sensitive as the human ear, in terms of the ability to distinguish gaps. The eye can see a gap in an image that lasts at least 20 milliseconds, rarely past 10 ms. The ear can hear a gap in a sound that lasts at least 5 milliseconds, rarely past 2 ms.",
"Instances of video/audio glitching are not generally caused by lack of bandwidth, but by latency spikes / packet loss. A latency spike or lost packet will affect the short timescales of audio signals (1 sample every 20-100 μs) far more than the long timescales of video signals (1 frame every 16-33 ms). Though in practice, individual audio samples are typically buffered several milliseconds in advance to provide some protection against packet latency. It also depends on the cause. Video and audio are *both* affected equally by networking issues, if the underlying cause is physical disturbance (e.g. EM interference). But if the underlying cause is due to network congestion, then the high-bandwidth video signal might actually help drown out the low-bandwidth audio signal, unless the audio signal is being properly prioritized by your router (\"Quality of Service\")."
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lb7mlo | How do freezers and fridges and stuff mke things cold? | I dont understand how you can remove heat from something | Technology | explainlikeimfive | {
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"It's important to understand that there are two related but distinct concepts at work here: **temperature** and **thermal energy**. Generally speaking, when you add thermal energy to a substance you raise its temperature. When you remove thermal energy from a substance, you lower its temperature. The most common way to transfer energy into or out of a substance is to place some *other* substance next to it with a higher or lower temperature. So, if I place an ice cube in my cup of water, the ice cube will absorb some thermal energy from the surrounding water because the water has a higher temperature. Now, here's where it gets interesting. There is another way to affect the temperature (but not the thermal energy) of a substance. If you compress a substance, such as a gas, into a smaller volume you will raise the temperature of that gas. **It's important to understand that even though we have raised the temperature, we have not changed its thermal energy at all.** By the same token, if we expand that gas back to its original volume, its temperature will revert back to its original level. We can exploit this phenomenon by repeatedly doing the following: * Compress a gas (temperature increased, thermal energy remains the same) * Expel heat out to the environment (thermal energy decreased) * Expand the gas (temperature decreased, thermal energy remains the same) * Absorb heat from the freezer compartment (thermal energy increased) This is known as the refrigeration cycle. Although you can theoretically use any kind of gas in this cycle, we use special gasses (refrigerants) because they have unique properties at certain temperatures that allow the refrigeration system to operate more effectively and efficiently."
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lb83a3 | How do services like Spotify create personalized suggestions for each user? | Technology | explainlikeimfive | {
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"They take music you listen to a lot, and use an algorithm to suggest music by similar artist or similar people. (For example, they would translate “if they listen to Rap God by Eminem suggest My Name is By Eminem” into JavaScript or whatever coding language they use"
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lb8ick | what is a computer doing when its "shutting down" why can't we just turn off the power and the machine stops working, and then works normally when we turn it on? | Technology | explainlikeimfive | {
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"It's making sure all the programs and processes are saving data and shutting down properly *themselves*, because data can be corrupted or even fully lost if the writing process just stops abruptly (that's also why they tell you not to turn the console off when your game is mid-save, for instance). You *can* just do a hard reset but you risk losing data if you do that.",
"Imaging if whenever the teacher says \"okay, that's it for today\", all the students stop mid writing, and just burst out of class all at once without listening to their assignements, or finishing their notes. That's similar to what happens to a computer when it's abruptly shut down, because the operating system is like a teacher, it's responsible for keeping all the apps and processes in check and provide them with their needs of memory and CPU power, that's why when shutdown a computer The operating system goes through the process of making sure every app and process have finished writing to memory and that there are no tasks to do before shutting down."
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lb9ixp | what is Kubernetes? | Technology | explainlikeimfive | {
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"Kubernetes is a container orchestration solution. Containers are mini-computers that run on someone else's big computer. Sometimes, people or businesses like being able to run lots of mini-computers rather than maintaining their own fleet of big computers (due to physical space, cost, maintenance, etc.), and Kubernetes helps you manage all the mini-computers that you have running in various big computers.",
"So... businesses started realizing that setting up a bunch of “containers” on physical servers was a much better way to allocate resources. Each of these containers was its own virtual computer, so now the apps they host are no longer fighting with each other for resources. It’s like turning one computer into 20 computers and they’re all completely isolated from each other. This is great! But what happens when you have to start managing 10,000 of these containers? 100,000 containers? Google was spinning up over 2 BILLION containers a week and learning through trial by error how to manage all of them. That trial and error led to the creation of kubernetes. In 2015 Google decided to donate kubernetes to the open source world and so now here we are. It’s a way to manage all of your millions and millions of containers and it does it so well that it became an industry standard shortly after (duh, it was Google’s personal solution for managing their enormous, ENORMOUS infrastructure. Also Redhat deserves a shoutout for their contributions to kubernetes)."
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lb9l3a | How is audio digitally stored and reproduced? | My understanding is that computers, at their hearts, can be broken down to the 1’s and 0’s of binary. Photos and videos can be stored this format by determining how much red, green, and blue light to shine through each pixel. But what about audio? I could imagine a song being broken down into a collection of pitches at certain volumes, but what about the different tones of various instruments/voices? When a singer’s voice is recorded and played back, it is their specific, unique voice that is heard. How can something like that be broken down into raw data? | Technology | explainlikeimfive | {
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"Hi there: audio engineer here. I'm going to answer your questions backwards as I think that'll make the most sense. & #x200B; The most basic tone possible is a simple sine wave. The reason that different instruments/voices/noises all sound unique, is because they all have different harmonic content, related to the base sine waves produced. Each one of these harmonic frequencies are sine waves all on their own, with their own associated harmonic frequencies. This complicated mess of waves is what gives everyone a unique voice, and every instrument a unique timbre. However, when all of these frequencies hit your eardrum or the diaphragm of a microphone, they all average out into one wave. The high/low points of each sound is effectively averaged out, the final product being one wave. Imagine the compressions and decompressions in your eardrum could be translated into electrical signals-This is how analog audio is produced (albeit extremely simplified. Let me know if you want to know about that process) & #x200B; We are let with a series of positive and negative voltages, that with properties such as amplitude and frequency, are able to reproduce the sound they represent. Now we introduce an Analog to Digital converter, also known as an A-D converter. This is a device that takes digital snapshots of the analog signal at a defined rate, called a Sample Rate. The most common Sample Rates are 44.1kHz and 48kHz. Each snapshot it takes, it uses strings of binary information (1s and 0s) to represent the voltages in the analog audio. Essentially, a camera takes a photo of the signals position 44,100 times every second (or up to 192,000 per second.) That \"photo\" contains bits that are represented by the 1s and 0s. The amount of bits can vary too, according to the Bit Depth. Bit Depth is usually 16 or 24, and all it means is how many bits are used to represent the position of the signal during every sample. & #x200B; Simply put, using CD standard of a sample rate of 44.1kHz and a bit depth of 16, every second you have 44,100 samples represented by 16 bits each. That is the analog audio represented digitally",
"Audio is just a funny way to vibrate air, it doesn’t matter whether it’s a whole orchestra, a singer, or a simple digital beep, it’s all just moving air, as long as you can somewhere how much the air moves, you can record the sound Back in the really old days they just used a needle to scratch some wax, the moving air moved the needle and the scratch encoded the movement, put a thing in the hole and spin the wax the same way, you make the thing move like the needle and you record the audio A microphone turns air movement into electricity and a digital recording uses an ADC to measure the voltage and store it as a number, and does that a few tens of thousand times a second To play it back you use a circuit called a DAC to turn the number back into voltage and a speaker moves air again so you can hear it",
"The key to storing anything digitally is to represent it as numbers, because that's exactly what binary is, a number system. Sound is just a vibration in the air (it can also travel through other mediums but let's keep it simple). A microphone is a device that uses that vibration to move a magnetic coil, which in turn produces an electrical voltage. If you take many samples of that voltage over time (say, 44,100 times per second) then you have effectively captured the sound wave as a stream of numbers. You might then record those numbers more or less directly into a file (uncompressed - eg. WAV) or find some way to identify repeating patterns or represent sound wave changes mathematically (lossless compression - eg. FLAC), or find more efficient mathematical expressions which approximate the sound wave or remove sounds humans aren't good at perceiving (lossy compression - eg. MP3). Reproduction of the sound at the other end is then simply a matter of using the voltage levels to move a magnetic coil which recreates the vibration in the air. That's right, a speaker is fundamentally the same thing as a microphone! Nowhere in any of this does the computer need to 'know' about pitch, tone, timbre, volume or any other property of the sound, those attributes which allow us humans to recognise the voice of another individual, or tell the difference between a saxophone and a flute. It's just blindly recreating the sound wave."
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lbbzr5 | How exactly does the clock in a laser range finder work? | How exactly do laser range finders work? I know that it uses distance=speed of light\*time by measuring the time it takes light to travel to the target and bounce back. I've seen a laser range finder accurate to millimeters. However, it takes about one nanosecond (one billionth of a second) for light to travel one foot. This means the clock inside the device has to be accurate to fractions of a nanometer. The problem is that quartz clocks are only accurate to about 1 part in 500,000 (a higher error means it will be off by more than a minute a year), which is too inaccurate. Clocks that are accurate and precise enough to measure nanoseconds must be atomic clocks. However, I'm reasonably confident that atomic clocks aren't used for handheld laser rangefinders. Can someone please explain how these devices can be so accurate while using light (ie, the fastest thing in the universe)? I don't know which of my assumptions are wrong. Please help me understand. | Technology | explainlikeimfive | {
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"I'm not entirely sure, but I don't think that laser range finders rely on time of flight analysis. They follow more amplitude shifts, interference and pulsing the laser and averaging out the data. I more work with like laser scanning of surfaces and in that case, we use interference patterns by comparing a mirror surface to a rough surface by splitting a single beam of light. In cars for example, Lidar relies on doppler shift rather time of flight, so by combining data from the car's speed and how much the laser phases changes upon reflecting off an object, this is how you can tell the distance to the object. Time of flight on laser analysis is extremely complicated, as you can read about the ligo experiment which detected the gravitational wave shift. But again am leaving this here hoping someone corrects me."
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lbcaeg | How do smoke detectors know that there's smoke around? And how do they make it infinitely reusable? | Technology | explainlikeimfive | {
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"Inside a smoke detector, there is a small amount of radioactive material between two electrically conductive pieces of metal. The radioactivity causes the air between the plates to ionize and conduct electricity. When smoke enters the detector, this ionization is interrupted. This causes a change in current between the plates, which the detector can sense. ETA - This is also why the detector is reusable. There's nothing about this setup that would change after smoke is detected. The half-life of the radioactive material in the smoke detector is about 400 years, so you don't have to worry about that part either.",
"You've got a couple of descriptions of Ionisation Smoke Detectors but as these have proven to be not reliable to an accepted standard, many places around the world have legislated against the use of them and instead favour photoelectric smoke detectors instead. Photoelectric (or optical) Smoke Detectors have a light chamber with an LED and a light sensor inside. When smoke particles enter the chamber the light beam is scattered and the alarm is activated. You can get a lot of false positive alarms from these (such as from steam from cooking which is why it's only recommended to install near a kitchen and not within the kitchen) but they are a lot more sensitive than Ionization types with tests demonstrating smoke detection 2-6 minutes sooner in photoelectric models. The parts that detect the smoke are not consumables so they will continue to work for quite a long time (most recommend replacement after 5-10 years with annual or bi-annual battery replacement and checks to make sure they're working correctly)."
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lbjmld | What's the objective difference between a 'horror', 'thriller', 'phycological thriller', 'physcological horror' and 'physcological drama'. | I can't keep up with all these film sub-genres. What's the difference between them? Or is best to think of the genres existing on a spectrum? Black Swan for instance is labelled as a phycological drama, but felt more like horror to me | Technology | explainlikeimfive | {
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"The way I look at it Horror : basic hack and slash movies, blood/guts/gore “Friday the 13th” Thrillers : Not that scary/gruesome, but has “creepy” things such as “Bird Box” Psychological thrillers : same as above most most of the movie revolves around tricking your mind such as “Get Out” Psychological horror: mainly focuses on mind games and whatnot to disturb viewers as much as possible such as “The Grudge”"
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lbkawt | How do bombs work? | Technology | explainlikeimfive | {
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"Bombs generally do two things, create a lot of heat and/or create a lot of gas. Both of those things cause rapid expansion, new volume is being created faster than the air around it can move out of the way, this creates a shockwave which is what does most of the actual damage."
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lblebk | How does remastering old games work? | Technology | explainlikeimfive | {
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"For the majority of people, remastering generally means \"make this shit look better\". That said... It's important to note that in most cases with a game, the assets are developed in very high quality and down-graded to something smaller when placed into the game, for RAM, speed or hard drive space reasons. The original models for Doom 3 were insanely high quality and used to help fake the visual effect in-game. What you see in-game looks similar to the original high quality models but takes up a lot less space and runs *much* faster. This is done in general for most game development because you can always downgrade it less at some point, but if you create it in the intended crappy quality, there's little to be done if you want to up the quality. It's like creating a super high quality GIF and then resizing it depending on your monitor. You want a 4k image, preferably. That won't look any better on a 16k monitor than a 4k monitor, but maybe you don't care about \"16k-compatible\" but if you used a 1440p image, you can't really claim \"4k-compatible\" because it won't look any better on a 4k monitor than it would on a 1440p monitor. **Option A: Re-use** Sometimes they use the original game and just apply better-looking assets to it (models, sound effects, flashier shaders, smoother and/or more realistic animations, etc.). Maybe they make some code changes to the game to make it run a little faster in light of some new technology since the original. This is what's happening with Mass Effect Legendary Edition. **Option B: Recreate** Sometimes they start from scratch and are basically creating a new game using the original as the design plan. This is what happened with Final Fantasy VII Remake and I'm assuming what's happening with Diablo 2 Resurrected. **Option C: Mix** Maybe they re-use the original assets but start coding from scratch or switch to a new game engine. I know this has been done but I can't think of any games off the top of my head. [Edit] Mix is Warcraft 3: Reforged. It’s a new engine with updated assets."
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lbmhax | why is it that voice output systems can produce naturally sounding speech most of the time but then sound like robots with certain phrases? | For example when I get an auto reminder call confirming an upcoming doctor appointment the part about the doctor's name, address etc sounds natural but the part about the date and time is robotic. So whats preventing the whole thing from sounding natural? | Technology | explainlikeimfive | {
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"Inflection has to be programmed. Each word and phrase is typically only programmed to put emphasis and inflection in the forest way the words are recorded. That’s why names (uncommon ones unlike Clark or Smith) will sound very robotic.",
"Most likely what you are hearing is an actual human speak most of it, and then a computer just filling in the variable stuff. Alternately, it might be all artificial but the software is set up to put pauses between the variable things to make it easier for you to pick out the key information."
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lbn2lj | Why is it so difficult to emulate PS4 on PC? Is it something Sony intentionally prevented in development or the architecture itself? | Technology | explainlikeimfive | {
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"They did not intentionally prevent emulation but they did make several design decisions which had the unintended consequence of making emulation dificult. Firstly games consoles are very dificult to emulate because they typically use a different archinecture. This means that every single processor instruction have to be translated into instructions that the computer understands. And there is usually no one to one mapping between these. This means that in order to be as fast as the console the cumputer needs to run at much higher clock speeds. But the PS4 is already running at around 2 GHz which is very close to what even modern computers are able to run at. And even though they did go for the same architecture as found in computers meaning there are more one to one mappings between instructions they included a graphics processor which you will not find in most computers. The PS4 also includes a lot of other advanced controllers outside of the processor. While these are of the type you may find in a computer they are not connected to the processor in the same way. And you are not going to run the PS4 software on a home built computer but rather need to emulate it so you can not use any of the devices on your computer directly either. We are able to emulate one computer on a computer. But this is something that took a lot of effort. The processor itself does have support for virtualization so that it does not have to be emulated. However all the devices in a computer have been painstaikingly emulated by some software. And there are not many devices which have gotten this treatment either as it is a very big job. You have to repeat this all for the PS4 and all its devices, including the graphics card."
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lbnmi1 | Why does Task Manager force-close applications more effectively (Windows 10)? | Technology | explainlikeimfive | {
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"There's essentially two ways of shutting down an application. Once is graceful, and one isn't. When you hit the close button on the window, it starts a graceful shutdown. This means that the program is allowed to interrupt this process. For example, it might ask you to save the document you're working on. This means that if the application is misbehaving, it might not respond to this signal and not actually close. When you do a force close from Task Manager, it does a non-graceful shutdown of the application. This means the application is not allowed to interrupt it. Instead, the shutdown happens entirely from the OS side. Essentially, it's the difference between asking someone to resign and having them clean out their desk, versus having to have security escort them out.",
"When you click the X you are asking the application to finish up whatever it is doing and shut itself down safely. When you kill it with the task manager, you are telling the operating system to turn it off hard - just deallocate its memory and stop any code it is executing. Analogy - the x is your mother asking you to pause your game and come to dinner. The task manager is your mother unplugging your computer and dragging you by the hair to dinner.",
"Imagine you're in a crowded grocery store. Hitting the close button is politely saying excuse me to the person in front of you. Normally, the person hears you and moves. It may take them a moment to adjust their cart or stop what they're doing but they're able to get to it pretty quick. Now imagine the person in front of you is on the phone. They're super busy with their task, they don't hear you. It doesn't help that the store is crowded and loud. You could wait and hopefully they process that someone is behind them waiting, or you could take the task manager approach which is essentially chanting a Ludacris song while shoving past them. Scenario 1. No hard feelings between you and the person. When you might again things are cool. Scenario 2. Because of the negative interaction, there may be issues next time you cross paths. Edit: Windows is trying to aim for scenario 1 when it can.",
"Normally a Windows application runs in an \"event loop\", processing messages. Messages are things like \"The user moved the mouse\", \"The user pressed the 'a' key\", \"The user clicked the close window button\", etc. Sometimes applications stop processing those messages and if that happens, they don't react to the X button. This is why the task manager can dispense with the niceties of telling the application it should exit, and just kill it outright. And the reason why the X button works differently because you normally want to let the application a chance to react, and ask \"Are you sure you don't want to save the last 6 hours of work?\". Killing it just stops it immediately, and as a result it won't get a chance to do anything of the sort, even if it's working perfectly fine.",
"> one which works in all cases? Heh, as an IT guy I can assure you sometimes you still have to use the fourth option."
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lbpqg7 | How did we figure out pickling food before we understood bacteria? | I understand that preserving food by pickling it has been around for awhile, but without understanding the relationship between bacteria and food decay I have no idea why we would be soaking food in vinegar for months at a time haha. | Technology | explainlikeimfive | {
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"You don't need to know of bacteria to know their effects and how to preserve food. Essentially people just tried everything until something worked and then tried variations of that. They probably first noticed that the vinegar didn't spoil then figured if they put stuff in it then it wouldn't spoil as well.",
"We didn't really understand food spoilage, in a modern sense, until the mid-1850's when Louis Pasteur studied fermentation and germ theory. Food preservation in practice prior to the 1850's was based on experience which often got intermingled with faith/magic. Food was preserved by drying, smoking, pickling/brining, fermenting, and salting; and in practice there is a large overlap in these techniques, for example drying and smoking were often done together. The end result is making the food inhospitable to spoiling microorganisms by removing water, removing simple sugars, adding toxins (alcohol, phenols/tannins, acids), removing oxygen, and adding large amounts of salt. All of these inhibit the growth of harmful bacteria and in some cases actually add nutrients we couldn't get otherwise. So it was trial and error, we knew that if we fermented grapes or grains it was safe to drink. If we re-fermented the wine/beer into vinegar it was still safe to drink. If we then added the vinegar to pickles it kept the pickles safe to eat. This wasn't one off, most of our condiments are produced by fermentation and that's kind of why condiments are condiments, they made our food safe to eat. It's worth noting that this trial and error was ongoing for thousands of years. For several centuries beer was made with \"magical\" equipment (that was just inoculated with beneficial microorganisms) and could only be brewed with \"blessed herbs\" sold by Catholic church. These herbs contained tannins and phenols that made the beer bitter and helped preserve it but could also be pretty harmful to humans. It wasn't until the 1600's or so that brewers seeking to get around the Church tax for magic herbs started using Hops to bitter their beer, which also contains powerful anti-microbial agents, that modern 'Beer' really came into existence."
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lbprik | Why do some bank and payment processes still take 3-5 days to complete? | Technology | explainlikeimfive | {
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"text": [
"A live person at the bank has to verify certain transactions, which usually involves talking to another live person at another bank or branch. Combine that fact with the workload of large banks, which process god knows how many transactions daily, and the fact that most bank employees have to split their work day between multiple roles/types of work, and it’s no wonder it takes 3-5 days. Example; if I have 80 phone calls to make, but I also have to work the bank’s drive-through and answer phone calls, I probably won’t make them all on the same day.",
"3-5 days is the reversal window for EFT/ACH in the US. There are also 60 day windows, but those require manual intervention by the bank. A lot of the 3-5 day ones can be automated. Generally, they make it available if you have enough in the account to cover the transfer being reversed, otherwise, they wait for it to \"clear\"."
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lbpszi | What's the difference between Eevee and Cycles in blender? | What changes between the two? Is one cleaner than the other? More precise ? | Technology | explainlikeimfive | {
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"text": [
"Cycles simulates photons and gives physically accurate lighting. This takes a long time to calculate but generally looks very good. Eevee is very much like a game engine- it will use all the shortcuts used in games to make a believable but not physically accurate image. It fakes a lot of the lighting effects and other such things as seen in the image frame; screen space reflections, for instance, will not reflect anything you don't already see in the image, i.e. anything behind or to the side of camera where Cycles will reflect everything in the scene. Glass is an obvious limitation too; generally it looks ok, but it can't make glass that has back facing surfaces(like water glasses) because it relies on the depth of the image to make refractions and other effects, not the actual geometry you use- so what's behind the front of the glass can't be \"seen\" by Eevee and it looks a bit strange. You can fake these things, and they will look good but not really accurate to real life. Both are great but it depends on what you use them for. Like they suggest, if you have a ton of stuff to render and need speed, like for a tv show, use Eevee. If you need highest quality, use Cycles."
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lbrvug | How does ink stay in a fine tip pen when it is not being used but comes out when being used? | Technology | explainlikeimfive | {
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"text": [
"It's all in the tolerances of the ball and the cone tip that holds it. It's actually not an easy thing to accomplish and up until a few years ago, [China wasn't able to do it.]( URL_0 ) Something like 80% of the worlds ball point pens were made in China but they used imported balls and tips because Chinese manufacturing simply wasn't able to hold the tolerances required to make the pens function properly.",
"Surface tension, basically. If the ink was more free-flowing, it wouldn't work. Fountain pens are an evolutionary step on from a dipper/quill which would work by having a textured surface and a narrow channel for the ink to flow down."
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"https://www.forbes.com/sites/timworstall/2017/01/18/chinas-ballpoint-pen-victory-or-why-american-wages-are-higher-than-chinese/?sh=eb116d4711db"
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lbxwan | How do municipal water systems keep water pressure consistent with people turning on/off water at all different times and rates? | Technology | explainlikeimfive | {
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"text": [
"Water systems are plumbed in parallel. To make up some numbers here, a water main that services say 100 homes has enough flow to support all 100 homes. If one of them opens or closes a faucet, the marginal change in available flow at the main is only 1/100th of what it can supply. The short answer is that water pipes are sized to provide enough at relatively constant pressure. The other answer is cities store water in tanks on hillsides or in towers and can increase flow into the pipes rather quickly to meet demand. Some cities use pumps but the result is the same."
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lc2n48 | Why is it that so often the moment I hit "wait for the program to respond" does a previously frozen program start working again? | Technology | explainlikeimfive | {
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"text": [
"You are stopping the loading process; like when you close a website that's stuck and see everything load just as it closes. I don't recall right this moment what the terminology was, but it creates less strain on the program on websites. I personally have never had a program load after hitting wait; if it's stuck it stays that way until I reopen it. Websites is an entirely different thing."
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lc3ci8 | What can a computer hacker do with a personality profile of yours? | So I just read a pro tip about not taking online personality quizzes because they will be sold to people who might not have your best interest at heart such as marketing agencies (makes sense) and hackers. I just can’t imagine anything a hacker really could do with that. Or would want to? | Technology | explainlikeimfive | {
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"glxmysq"
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"text": [
"There are a lot of questions that are asked that are similar to security questions asked by banks and other financial instructions. Others ask things like do you prefer chicken or turkey. That can be used to target ads to you. Most are harmless."
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lc3fys | What does .docx do that .doc could not? | Technology | explainlikeimfive | {
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"text": [
"docx is a cleaner and more modern format. It’s compressed, too, so it ends up being a smaller file. docx files are actually zip files. If you change the file extension from .docx to .zip, you can unzip the file and see what is inside. There are folders in there and xml files which contain the different types of data that can go in there. Note: Copy the file first before you unzip it so you don’t break your original file.",
".doc was a proprietary binary format whereas docx is a zipped xml document. This gives docx a very clear advantage and you can read data from it easily in any programming language as well. It’s way more efficient and less likely to become corrupt.",
".docx stores the information in the document in a different way. This method is more space efficient and can be read from and written to more quickly.",
"Doc: Puts the data in blender to make it raw computer data (binary) Docx: Takes your document and stores it in a way similar to an organized bag, which makes it easier to be used by other software, convert and work with."
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lc552n | - What does it mean when a video game is powered by a certain "engine"? | ETA- Thanks guys, that was very helpful! | Technology | explainlikeimfive | {
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"Developers don’t write most of the code in their games from scratch. Instead, they either develop or purchase a toolkit that already includes most of the code required to run the underlying systems the game relies on. Then the developers use the core “engine” and associated frameworks to assemble assets (artwork, music, models, etc.) and their unique game logic.",
"Say I write a program that simulates basic 3D shapes like balls, cubes, toroids, etc and allows them to interact with realistic physics. I could use this program to make a bunch of different games by arranging shapes in different configurations and setting goals for the player. I could set hoops at two ends of a plane and have the goal to get the ball into the hoops. I could set up boxes as goal posts at either end and make something like soccer or football. I could invent a game that had nothing to do with a real life sport at all. But at the end of the day, it’s the same underlying program powering all of the interactions that make up the game. That’s basically what a game engine is. It’s a program with a bunch of pre-built features that can be used to make a game, so that the developers of the game don’t have to reinvent the wheel and build a bunch of basic stuff from scratch. That way, they can focus on things like character or level design, and any real programming that needs to be done can be focused on unique features they want to custom build for their game rather than wasting a ton of time on very basic stuff that has already been done a million times by other people.",
"The engine is simply the program which was used to make the game. You may have heard of the \"unity\" or \"unreal\" engines. These are commercial engines which anyone can download and... make a game with. A lot of developers just build an engine from scratch to suit a specific game they have in mind (and to avoid paying royalties in using someone else's engine) Edit: interesting factoid, Bethesda has been using the same engine for their games since 2002's TES 3: Morrowind, although heavily updated and modified. Fallout 76 even had a few of the same glitches that Morrowind had",
"Developing a video game can be quite complex. However, every video game has certain similarities. For example, there's usually an environment that needs to be rendered with shading, reflection (all the things to give it a certain look & feel); there's an agent (your character) that the user controls; there's things in the environment that the agent can interact with. So as not to reinvent the wheel, the game developers will use an engine that takes care of these very common tasks. A physical analogy might help. For example, a set of cars from a certain manufacturer might be built on the same type of chassis/frame. This reusability means that they don't need to start from scratch for each car."
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lc6sxm | what are non-fungible tokens and how do they work? | Technology | explainlikeimfive | {
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"text": [
"Imagine I make a big spreadsheet of numbers. For every number, I leave a space large enough to put somebody's name. Anybody who asks me gets to put their name next to their favorite number. Say you go ahead and reserve your name for the number 17. That number now has your name next to it. The only way I can put somebody else's name there instead is if you give me permission to erase yours, first. So if somebody else wants to have their name next to the number 17, they'd have to convince you to let them. Somebody who just really, *really* wants to have their name next to the number 17 spot might even be willing to pay you $5000 just so they can put their name there instead of yours. Of course, they *could* just put their name next to the 18 spot, which is still free. But that's of no importance to them - they want the prestigious *17* spot, not the lousy stinky 18 spot. If that sounds insane, that's because it is."
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lcc7qj | Why are sites like Spotify and Apple Music so strict in marking explicit music, while there are thousands of videos and songs unmarked on YouTube? | Technology | explainlikeimfive | {
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"text": [
"You can upload anything you want to youtube, and there's no barrier for entry. You're not paying youtube to watch someone's video, so the obligation to correctly indicate explicit language falls on the uploader; uploaders are lazy and no one's kicking up much of a fuss about it, so youtube doesn't care. On spotify or apple music though, you're paying money for a curated collection; you expect a certain level of quality because it's costing you $10 a month, or however much you're paying. Just as it's expected that songs have the correct titles and artists attributed to them, music streaming services are expected to mark explicit content, since they're the ones providing it."
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lcc8rf | How do zip files work? How do they make files just smaller? | Technology | explainlikeimfive | {
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"text": [
"The trick with a file compression algorithm is that you try to find repeating patterns in a file. And when you find a repeating pattern, instead of keeping the entire pattern again, you type in a reference to the first place in the file where that pattern occurred. Works better, of course, if patterns have the decency to repeat themselves often. Or a least similar.",
"Compression is a form of coding. When you find a specific pattern or grouping, you assign that group a simple name, then replace all the reference with the simple name. For example, a long essay, you find the word “the” occurs 1200 times in the text. You add a statement that says replace the letter sequence THE with the number 1. So for each time the word The appears, the compressed form has the number 1. You’ve now reduced the size by 66% for each occurrence of the word. The more times a file has a repeating pattern that can be coded smaller, the better the compression ratio will be.",
"I have a bag of 15 marbles. There are several ways I could tell you what colors the marbles are, but here are 2 major ways. The first: 5 blue marbles, 3 red marbles, 2 yellow marbles, green marble, 4 purple marbles. This is an unzipped file. The second I will show you is this: Same information, but shorter, if you know how to read it. 5b,3r,2y,g,4p This is a zip file. Unlike the first, it doesn't mean anything unless you know the symbols used, but it's easy to convert it back to English if you do. Anyway, the actual method will vary a bit, but file compression such as zips use similar methods to take the same information and smash it down to be smaller, then make it bigger again when needed."
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lcdcqs | What is a .zip bomb and how it works? | Technology | explainlikeimfive | {
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"text": [
"imagine that you're packing up for a trip, you compress all of your clothes in a small bag you successfully zip it close, but when you arrive at your destination, you open your bag, everything comes out, a shit ton of clothes scattered on an area zip bombs are, well, compressed files, usually just a single text file with at least 1 byte of data or more, then compressed, made duplicates, compressed, duplicate and so on until you're left with 1 zip file that when unzipped, consumes a lot of storage space",
"One thing that the other answers don't indicate well is how you can compress so much material into a small file. It has to do with the nature of how file compression works. Imagine I had a 1 GB text file, but every character in the file was just the number \"1.\" In a compressed file, this might be compressed by simply giving the instruction, \"'1'x1GB\". And so a very tiny compressed file (7 characters in my fake example) could be turned into a gigantic file on the other end (~1 billion characters). When your computer opens a ZIP file, it follows a set of rules according to what the file says it has inside of it. A ZIP bomb is a ZIP file with rules that are intentionally malicious. It's basically a little file that says, \"spend all of your time and energy and memory writing out meaningless junk.\" (And in this case it has to be meaningless, if the compression ratio is going to be that high. The reason that ZIP files can only compress \"real\" data only so much is because real data has structure and variance most of the time, and so there's only so much you can do to reduce that to instructions like this, which generally focus on repeated sets of characters.) For an ELI5 analogy, imagine I have someone who types up my notes for me. Except I don't have to just give them my notes; I can put instructions on the notes. So I send them a tiny Post-It note, but it says, \"write the number 1 a trillion times.\" In real life, the person would probably laugh and/or quit the job, but your computer doesn't have that option — unless its programmers anticipated this problem (which some modern archive programs might), it will just dumbly follow the instructions in the file, even if it is ruinous for the overall machine's performance.",
"A zip bomb is just a zip file that contains very well compressed stuff, and typically contains more zip files. Getting a 1000-to-1 compression ratio (that is, 1 megabyte ZIP file expands into 1000 megabytes of files) is doable, and would be a good first step in building a zip bomb. Do this a few times, put a few copies of the resulting ZIP file into a ZIP file, maybe ZIP that up, and so on. If you were to extract the ZIP file the RAM and/or disk usage would be shockingly high. There is a well known zip bomb named 42.zip, known for being about 42 kilobytes, and decompressing into terabytes of data when all its layers are fully unpacked. There is also a proof of concept zip file that contains 2 files: a picture, and then *itself*, resulting in an infinite ZIP unpacking process. There is software, most notably antivirus, that will unpack ZIP files because automatically. Zip bombs were originally designed to wreak havoc on these programs. They have since been modified to recognize a probable zip bomb and deal with it, probably by detecting it as a type of virus by itself."
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lcf5a0 | how can special body scales detect what you are made of, like body fat? | I have some physical understanding, but how can they tell my body fat % and how accurate os that? | Technology | explainlikeimfive | {
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"Imagine you're standing on the scales with bare feet. The scales send tiny bits of electricity into one foot, which travels up one leg, down the other, and out the other foot and back into the scales. Electricity travels through fat and muscle (and even water) slightly differently, so depending on what the scale gets back through the second foot it can work out what you are made of. They don't measure your fat and muscle in your upper body, so the result is mostly just your legs. They aren't very accurate, because as mentioned earlier electricity also travels through the water, which will mess up the results the scale gives you. They can be used to measure fat gain/loss over time, however, as long as you're never really thirsty.",
"It uses something called bioelectric impedance. Fat and muscle conduct electricity differently because muscle has more water content while fat is an insulator (slows down electricity). The little silver parts you stand on send out a super small electric signal that you can’t feel but it measures how quickly it goes out one silver piece and back into the other. Since it knows how fast it goes through water/muscle and fat, it can estimate how much of each it went through. It also uses characteristics such as age to help it be more accurate. BIA is accurate to within roughly 3-5% under perfect conditions, but how hydrated you are, your body temp, etc can alter results quite substantially."
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lcm091 | what big data is and how it is useful | I'm reading a lot on this topic and I cannot understand it | Technology | explainlikeimfive | {
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"Big data = harvesting all sorts of data on a large scale, such as spending habbits, geographical locations, psychology, sleeping habbits. Literally anything you can think of. Why is this useful? Well companies can come along and purchase this data collection, reinterpret this data and get useful information out of it. The idea is pretty terrifying, since it's not just being used to push adverts on us, it's been used for more nefarious things.",
"Big data is basically what it says: loads and loads and loads of data. In very simple terms, it is the process of collecting, storing, and analysing vast vast amounts of data for a particular purpose. For example, if you had a way of tracking every single fish in the sea, you would be able to learn huge amounts about sea currents, migratory patterns, fishing impact, etc. It has become a buzzword recently because advances in storage space means we can store far more data than before, advances in computer science mean we can design much better algorithms for analysing data, advances in computer hardware mean we can have much more powerful computers to run those advanced algorithms, and advances in other technology mean it is much easier to collect data. It has also gained a lot of focus in the public eye, as it is often linked with the collection of people's personal data by big tech companies and/or governments. For example, Facebook collects huge huge amounts of data on the behaviours on individuals online, collected from all sorts of sources such as Facebook itself, your browsing habits, your shopping history, etc etc. It uses this data to learn all sorts about you (and others), and can e.g. sell your profile to advertising companies or others. Facebook and others can also look at the data in bigger chunks, to learn all sorts of insights about how larger populations behave and act. You will also find it linked up with other buzzwords such as \"AI\" or \"machine learning\". This is because those technologies (or linked technologies that are mis-labelled as them) often underpin the newest and most advanced algorithms used to analysing data."
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lco4z6 | When you take a picture of a computer screen using your phone, why do those waves on the screen move as you zoom in/out? | Technology | explainlikeimfive | {
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"Not exactly sure I understand your question, but what you are seeing is probable a [moire]( URL_0 ). These occur when you overlay two grids that don't perfectly line up. One grid is the computer monitor (consisting of square or rectangular pixels arranged into rows and columns) and the other grid is you camera's digital sensor, which captures light falling on individual pixels arranged in a series of rows and columns. Since you can never perfectly line up your phone to your monitor and because they're also going to be different resolutions (pixel size), you get a moire."
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lcqfcv | How does a battery charge cycle work? Why is it not recommended to fully charge a laptop or smartphone? | Technology | explainlikeimfive | {
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"A rubber band does not hold as tightly if it is constantly stretched. Batteries are similar, though some technology and kinds of batteries are better at this. Modern phones (i have heard) are totally fine if you charge them to the maximum."
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lcu2i8 | Why is stenography still used in courtrooms when microphones exist? | It seems like it would be much easier to just set up a microphone and record everything that's being said in a legal setting rather than having someone type it out. edit: This is in no way meant to discredit stenography or those who practice it. | Technology | explainlikeimfive | {
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"A transcript is an undisputed record of what occurred during a legal proceeding. During a proceeding the parties can and frequently do have the transcript read back to make sure that everyone is in agreement with what was said. If they're not in agreement then they can correct the transcript right then, when the substance of what was said is fresh in everybody's mind. This is particularly important because people frequently misspeak and say one thing even though they meant another - which is something that is easy to correct on the transcript if its caught at the time that it was said. An audio recording is not an undisputed record - even if no one misspoke, people can hear the exact same audio and come away with two completely different understandings of what was said. Before you used an audio recording as evidence of what was said during a proceeding you would first need to reduce it to writing so that you could have an undisputed record. That's much more difficult to do when no one remembers exactly what was said because this is being done months or years later. Ultimately you would need an entirely new trial with an entirely new jury to listen to expert testimony and determine what was said during the original proceeding. Rather than dealing with that, the court just appoints a neutral expert, IE, a stenographer, to transcribe the proceeding as its happening. The court then gives the parties a limited, non-appealable window to check and correct the transcript. Once that window is closed the parties can no longer dispute what happened during the proceeding, which prevents a tremendous amount of needless litigation.",
"For the full transcript after the case is finished, that's true. But in court they quite frequently have to go back and hear the exact phrasing of something that was said earlier. This is not very fast to do with a digital recording. But a person doing it can just read their notes from earlier, which is a lot faster",
"There is also a few important points being left out. A recording cannot tell you who is talking if voices are similar. Also, if a response is garbled or hard to understand, the court reporter will ask clarification or for the speaker to repeat to make sure it is accurate. A recording can’t do that and a replay could have quite a few unintelligible responses.",
"Because it's not possible to flip right to a specific part of an audio recording, which lawyers frequently have to do during and after the case. By having it transcribed in written form, it's much easier and more efficient when you're trying to seek a specific part of the proceedings. Additionally, transcribing to writing removes any ambiguity in what was said, so two people can't hear different things when they review the audio recording.",
"My partner works in courtrooms here in the UK. The answer (at least here) is that both are used to complement each other. All court sessions are recorded (both audio and video, including digital evidence displayed on the screen), but a stenographer also records abbreviated notes, summarising key points and giving timestamps. When a judge (or anyone else) wants to look over the case, they use the written record to locate the exact points/moments they want to listen to. I'm not sure if this is different in the US, which has a lot of odd rules about what can happen in a courtroom."
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lcvg98 | How did people in pre-internet era sync time? | Technology | explainlikeimfive | {
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"I used to call a number that would tell me the exact time. Sometimes I miss the Time Lady’s voice lol",
"If you didn’t have access to tv, news radio broadcasts would regularly provide it. “The time is now 5:00 PM”.",
"i used to call the talking clock, basically a phone number and the voice would say “at the tone it will be so and so, then there would be a beep”",
"Really long ago, they had a lot of trouble with this exact problem. In some places they'd put a flag, or a ball mounted on a mast, on a very tall pole. Then when the flag, or ball dropped, everyone who could see it would know that was the agreed time. Sometimes people used bells ringing to communicate the time, which you can still hear in some cities that have clock towers or churches that ring the time. In others, they used cannons, setting off a cannon blast (generally with just gunpowder, no shot), so when people heard that, they knew. Of course, by the time radio came by, radio was immediately used to communicate the time - in many places the radio stations will announce the time along with the station broadcasting at regular intervals. Before radio, the telegraph was used. However, the idea of 'time zones' are relatively modern, and to my best recollection really started with the invention of railroads. Before the railroads, most towns had their own 'local' time, based on the observation of the sun. But a train can move quickly enough that a clock on the train won't match clocks in all the towns it passes through, so it gets really hard to schedule train stops at specific stations. So, the train stations had their own clocks, all set to the railroad's time, and that eventually led to the timezones we know today.",
"In Canada they still have the national research council broadcast the time with a series of beeps at 11am on CBC radio. I don’t know about before that though."
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lcyhfk | How does tap water stay cold. | How does tap water in pipes stay cold even if it's like a 100° day, wouldn't you expect it to be like lukewarm right. | Technology | explainlikeimfive | {
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"text": [
"Water pipes are buried underground. Once you get more than a yard or two below the surface, the earth has a base temp in the mid 60s Fahrenheit."
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ld02ec | How do helicopters descend in altitude while still remaining in the air? | Like, I don't get it. How do they lower their altitude without dropping to the ground altogether? | Technology | explainlikeimfive | {
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"text": [
"Say a helicopter weighs 1000 units. To ascend it creates 1100 units of lift or more. To descend it creates 900 units of lift or less. To dead fall it generates 0 units of lift.",
"They can change the amount of lift the blades supply by changing the angle of the blade as it rotates. Airfoils like helicopter blades are curved on the top and flat on the bottom to create lift but if they're angled downward enough it will start to create 'lift' on the bottom and reduce the lift on top."
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ld0hkw | How does Google Maps get its traffic data? | As a kid, I always assumed there were sensors or something but in hindsight that makes no sense | Technology | explainlikeimfive | {
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"From users phones. If you detect tons of phone in the same spot on the highway, not moving, you can assume there's traffic. A guy redirected traffic last year using that technique: URL_0",
"Google Maps tracks you in the background of your phone. They can estimate traffic based on how quickly or slowly a large group of users is moving.",
"It was explained to me that they use cell phone info. Not sure if that means the tracking of all phones per area or if that means data usage per area though I believe the same method is used for google to track pedestrian traffic in stores, like when you see the bar graph showing how busy Walmart is by the hour"
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ld42nr | Why do we have technology to heat things up really quickly but we don’t have technology to cool things down that quickly? | Technology | explainlikeimfive | {
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"text": [
"Having a hard time posting it but this tech already exists. They're called flash freezers and they do what you're looking for, though they aren't as efficient freezing as a microwave is heating.",
"It's much easier to turn energy into heat. It happens even we don't want to. We could freeze things very rapidly if we would had something like liquid nitrogen at hand. But storing that could be dangerous and very inconvenient at home."
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ld4yvg | Why copying 1x4000MB file is much faster than copying 4000x1MB file? | Technology | explainlikeimfive | {
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"Imagine you are sending out presents to a friend. Two options: 1: Make a giant box and throw everything in. Wrap it in gift paper. 2: Individually wrap each present. Option one is faster because you spend less time wrapping the gifts. The work required to wrap the gifts is called “overhead”. Back to computers. The transfer of files has the same overhead, consisting of, but not limited to: - access times on the reading and writing target - lookup of metadata to be transferred - interruptions on the transfer bus Hope this breaks it down for you 😊",
"The computer needs to write down the locations where it decides to store each file, so it can remind itself later where each one is when asked to find it again.",
"this has been answered, but i guess i throw in the analogy i use for that: if you have to drive 100 kilometres, it's faster to accelerate to 100 once and just keep going until you completed the distance, compared to accelerating to 100, then stopping, then accelerating to 100 again, then stopping again, and so on until you completed 100km.",
"Its the difference between doing a 4000 lap race in a car and doing 4000 1 lap races and getting in a different car every race. The second one is gonna take more time cuz your stopping to get a different car every race",
"File access is sloooow. Copying 4000 1MB files takes the same amount of time to copy the sum total of those files with the added overhead of 3999 file access operations.",
"This had a lot to do with the file system used too (FAT, FAT32, NTFS, etc). Without going into too much detail, these systems describe where files and their contents are located on a storage device. A very simplified example would be putting away files in a filing cabinet. Think of a set of index cards describing where your various files are located. If you only have one really large file, you have a single index card that says “stored in cabinet #1, drawer #1”. Need another copy of that file? Get one additional index card and write down a new location on that card and then throw the whole file in a copy machine and put it in the new location Now, instead of having one file, you now have 100 files. You now have 100 index cards that all contain the cabinet in which each of the files are stored. Want to make a copy of that information? You now have to find and count 100 index cards. You then have to write down new locations on each of those 100 index cards, you have to then throw 100 individual files into a copy machine and then you have to put each new copy of a file in the new location. It takes a lot longer. Actually, file systems work a lot like that. They have reference tables (e.g. iNode tables) that work conceptually a lot like index cards (overly simplified of course)."
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ldjdcl | How can authentication services make sure that your password is correct without having your password saved in plain text? | Technology | explainlikeimfive | {
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"text": [
"I take your password. I scramble it in, in a particular way. I will always scramble it up the same way. The way I scramble it up is very hard to \"unscramble\". (For an example of why it's hard, think of a number... now multiply by 743874283419234. Now take only the last two digits, swap them round, and divide by 7. You'll get a number. That number is the \"scrambled\" version of the number you thought of. But it's also the \"scrambled\" version of a lot of other numbers too. Which one was it? Who knows without trying them all?! And if I do this enough, and complicate it enough, and make it so that it could have been any number of things in the first place, then eventually it becomes secure). If I scramble your password up the same way, every time, but it's difficult to unscramble than we can have what's called a \"hash\". So you sign up to my website and you \"set\" your password. I don't ever store your password, I just scramble it up by following a set of instructions like the above. That gives me a hash - a scrambled version. That hash is made FROM your password, but it is NOT your password and we can't GET your password out of it easily. So all I need do now is store that hash. Next time you come to log in, you put in your name, and your password. I scramble that password you put in, and I scramble it in EXACTLY the same way as I scrambled it previously. If that scrambled password is the same as the \"hash\" that I stored when you first made the account... then I know that was you. And yet I don't know your password. The chances of two different passwords scrambling to the exact same hash is incredibly minute. Technically possible, but literally one of those \"once in the lifetime of the universe\" kind of things. So I don't need your password. I just need to scramble whatever you type in when you first \"set\" your password and put that somewhere. When you later try to log back in, I scramble what you typed in the same way again, and then see if the result is exactly the same as we did first of all. And I never need to store your password anywhere, just the scrambled version. Done properly, with clever maths, and appropriate methods used, it's incredibly secure. To the point that if a whole list of everyone's username and their scrambled password leaks out, nobody would ever be able to use that information anyway. This happened to the Steam gaming service, for example - but they had done it properly, so to this day, none of those passwords has ever been discovered. And, no, you can't just type the scrambled version into the password box. All that would happen if you did that would be that I would scramble it AGAIN, and it would end up different, and wouldn't match what I had stored, or what you typed in. You can implement this system poorly, however. And then people can sometimes \"unscramble\" those passwords, but that's still an incredibly difficult thing to do. And even that is so much more secure than what happens if you were just storing a big list of passwords in plain-text. Done properly, hashing is very simple in operation, very secure in practice, and very quick to do, while being very difficult to \"undo\". And if I ever want to \"reset\" your password because you've forgotten it and need to get back in? Then I can just take, say, \"password\"... scramble that up... and put the result into the database in place of your stored hash. Now you can login with \"password\", the scramble of that will match the hash I have stored now, and it will let you in so you can do whatever you need to do. But I still don't know what your password USED to be!",
"The authentication service doesn’t store the password itself. It stores a piece of data that’s *derived* from the original password. When a user enters a password later, the authentication service runs the same function on the *user-entered* password as was run on the *original* password. If the two results match, the passwords match. It’s tremendously important that it be very, *very* difficult to deduce the password from the saved piece of data. The idea is to make it so difficult that it’s easier to bribe or bully someone into giving up the password.",
"In simple terms, imagine that my password is password. Now the website takes the password and shifts each letter forward one place in the alphabet to get “qbttxpse” and then save that. They don’t have my password saved, but if I type “password” into the login box, they can run the same algorithm on what I typed, compare the result to what they have saved, and see that they are the same. In reality, the stuff they do to your password is *much* more complicated than this example and much harder to reverse engineer, but that’s the basic principle."
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ldkemn | Why do WiFi routers make a noise when loading something on a phone? | I noticed this morning that as I was swiping through posts, every time I swiped there would be a very quiet whirring sound coming from my router. If it was loading a video it would last slightly longer than a pic/text post. Additional question, why does my router make noise when loading something, but when I | Technology | explainlikeimfive | {
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"They cheaped the hell out on the router and the power supply circuit inside gets coil whine when the router actually has to do work. Well made units don't really do that.",
"It sounds like you are describing coil whine. Electronics have components that may vibrate/resonate with power draw. This vibration produces a whining sound (it might almost sound like chirping). For your router it may be that wireless transmission coincides with power usage and a coil whine. There’s a lot of videos/recordings of coil whine (mostly for computers/graphics cards). Check them out and see if it matches what you hear."
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ldlt2s | What/who is buying our personal data from Big Tech and why is it so valuable? | Technology | explainlikeimfive | {
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"Anyone who wants to sell a product, service or idea. The more someone knows about you, the better they can tailor their pitch to sell you on whatever they are trying to sell you. That’s pretty much the answer in a nutshell."
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ldtd0w | Shooting ranges require shooters to wear ears protections. How come these equipment are not always seen worn by active military members in real battlefields? | Technology | explainlikeimfive | {
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"text": [
"In real combat, there is often days or weeks of nothing between actual battle. Soldiers will often be issued with hearing protection and may have it with them but either not have time to put it on or prefer to be able to hear friends and foes now, and deal with the hearing loss later. Also, ranges tend to either be indoors or have roofs which amplify / contain the sounds while battles tend to take place outside.",
"Soldiers are issued hearing protection and are ordered to use it. And you do occasionally see soldiers wearing hearing protection or at least carrying them on they equipment. However a big issue in combat is that with all the noise it can be very hard to hear orders or other important information. This is also why helmets do not cover the ears. So soldiers have to chose between potentially damaging their hearing by not wearing the hearing protection or potentially losing their life because they do not hear an order or not hear an enemy sneaking up on them. Of course the right choice depends on the risks in the particular situation. But it is not uncommon for soldiers to skip hearing protection or just wear hearing protection in their right ear.",
"We have at least one radio operator, even in direct assault platoons. You need to hear if someone is running upstairs, etc, in a building. Your member with med gear may also need to locate someone, by sound / calls for help in a different room. In a lot of cases, it's better to eat the noise. Turret gunners may use them sometimes, but in other cases, they need us to coordinate with the radio, from the vehicles, too. Or somebody screams info up to them. Hopefully that helps answer some things.",
"They do, they're called Peltor combat headsets. They're active noise-cancelling, cancelling out the sharp cracks of gunfire and protecting the hearing of the wearer, while amplifying low-frequency noises like footsteps and shuffling and other things in the environment for situational awareness. URL_0 Not a perfect setup - You can get civilian models of these for a lot cheaper than the milspec ones, and they work but it's recommended to still wear a foam earplug under it. Beyond that, a lot of soldiers and operators just prefer to grunt it out. What's a little tinnitus to someone who's still alive after a massive gunfight?"
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"https://www.3m.com/3M/en_US/company-us/all-3m-products/~/All-3M-Products/Personal-Protective-Equipment/Protective-Communications/PELTOR/Headsets/3M-Peltor-ComTac-III-Advanced-Combat-Helmets-ACH-/?N=5002385+8711017+8713720+8720539+8720540+8720753+8726520+3294857497&rt=r3"
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ldwgzy | Why didn’t we use ethanol to replace gas in cars? It’s renewable, cheap, and has clean exhausts, seems like a great stepping stone towards clean high density energy before full electric cars. | Technology | explainlikeimfive | {
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"text": [
"It's not actually that cheap. To produce enough ethanol to replace gasoline financially we'd have to convert massive amounts of food producing land and convert an also massive amount of non-farmed land in to corn fields as well as build huge distilleries to convert the corn sugar in to ethanol. Ultimately we're better off financially just moving to solar and wind.",
"US centric post here. It isn't \"cheap\" in any sense other than it receives a rather large subsidy through the USDA - corn production is highly subsidized in the US so corn is artificially cheap and therefore make ethanol artificially cheap as well. Cheap though it is, there isn't enough ethanol production that could replace fossil fuels. There would have to be an area many many times that currently planted in appropriate crops. But this is a problem since more land generally leads to more deforestation and conversion of natural ecology to high yield farming. For example consider bio-diesel derived from palm oil which has considerably higher yield and is very competitive to fossil fuel diesel. Bear in mind these lands also produce FOOD which would increase in price if most of the product is used as fuel. There is widespread outcry over the deforestation and displacement of farmers for palm oil plantations. Many of these are subsistence level farms and they then go on to deforest even more and less fertile land leading to slash and burn farming. The production of ethanol in large quantities is still an industrial process. Because of the prevalence of the internal combustion engine, it is a reasonably good option but it cannot be anywhere close to an ultimate solution.",
"Not only is it not cheap to produce but the energy density is much lower. One gallon of pure alcohol has about thirty percent less energy than a gallon of gasoline. Alcohol is also hydrophilic it will absorb water from the air making it corrosive to carbon steel over time which is what most car parts are made of so you would have to change to stainless steel on most of the the fuel system and make them air tight or have desiccant systems to keep water in the air out of your fuel system. One last thing alcohol is also a favorite food stuff of certain bacteria which if left long enough will convert your fuel into vinegar and leave a huge clog inducing mess of biomass slime (read dead bacteria)inside whatever you have stored it in including your car’s fuel tank Edit 1 : thank you for the gold kind stranger Edit 2 : my first award",
"Compared to gasoline, it is very expensive. And we really can't grow enough sugar-rich crops to make enough, especially if we also want to eat. The only possibility for ethanol fuel is if someone cracks the way to make it from cellulose and lignin. Then it could be made from things like forestry waste, the chaff and fibre from cereal and sugar crops, and fast-growing grasses. As long as we have to use plant sugars, there isn't enough of them."
],
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ldxmyb | How does a government "block" its country's internet access? | Technology | explainlikeimfive | {
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"text": [
"Very easily. You get your internet access from an ISP. The ISP is a business with offices, employees and so on located in your country. The government simply sends people (armed if necessary) to said business and asks them to shut things down, or else unpleasant things will start happening.",
"In most countries there are internet service providers or ISPs they can control the “roads” to the internet. In countries where they can turn off the internet the government is the ISP or the ISPs are controlled my the government and can be forced to close the “roads” to the internet.",
"There are two ways a Government can \"block\" internet access. First: The Government just sends people to ISP's (Internet Service Providers) or passes legislation to shut down any form of the internet. Unlikely to happen though it can. Secondly: More realistically is an example of China and their Great Firewall basically all internet coming in and out of the country gets filtered through essentially a giant filter. If the website is allowed the connection will be allowed through if the website is blocked by the firewall it isn't allowed through. In more simple terms (Dumb analogy but oh well). If your Mum (The firewall) lets you have your friend over they can come inside. But if your Mum doesn't let the Dog (A blocked website) inside it cannot come inside."
],
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le3692 | Why does old news footage from the 20th century all sound the same? | For example: URL_0 URL_1 | Technology | explainlikeimfive | {
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"text": [
"What you are looking at is not news as we know it today but rather movie news. They are short movies made about current events and then distributed to the cinemas to be shown to a paying audience. People would visit the cinema to watch these reals maybe once a week. Most of the times they read the news in the newspaper or listens to the radio. But for moving high quality images of what was happening you had to go to the cinema. There is a few limits to making films in the early days and due to time and budget constraints the movie news were often some of the last places you had these limits. For example color cameras and film were much more expensive and cumbersome to work with then black and white films. So movie news were often black and white even when it had become common for the big Hollywood studios to make color films. Similarly sound was hard to work with so they often just dropped it. One problem was to collect and sync clean sound as you were filming but not all cinemas were able to play sound movies either. So the sound were usually made in the old silent movie style with a script for someone to read live to the audience and maybe some notes for an organist. The movies might have a sound track that included this voiceover and the music but could still be played on older equipment.",
"Not sure if it’s acceptable to answer with links, but this is a great article: URL_0"
],
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[],
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"https://www.theatlantic.com/national/archive/2015/06/that-weirdo-announcer-voice-accent-where-it-came-from-and-why-it-went-away/395141/"
]
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le95d6 | Why can a PC not just close a program? Sometimes, especially with poorly optimised video games, they will freeze and crash, but you can’t close them with keybinds or a task manager. | Technology | explainlikeimfive | {
"a_id": [
"gmakw08"
],
"text": [
"An important thing to know here is that programs are based on a foundation of \"tasks\" that run in the background. Some tasks are little pieces of software that feed the program information and keep it moving smoothly, others are the whole program running as one whole mechanical engine. Some programs need just the one big task, others have multiple smaller tasks that work together. Most games are single-task, meaning that this big gaming engine is being run through one stream of information. When a game \"crashes\", what it really means is that that task, or that stream of continuous information that keeps it running smoothly, has stopped running as its meant to run. This usually means that the window of the game freezes or even disappears, but under the hood, that task might still be trying to do what it's been programmed to do. But since it's \"frozen\" (not responding to commands), it can't respond to any new input. And so it doesn't understand that you (or the task manager directly) have told it to stop. Sometimes, these invisible frozen tasks can even prevent you from reopening your game without problems. They can lag your system or cause other issues. Usually these frozen tasks have a time-out that eventually tells them to stop, at which point it finally closes. edit: Fixed a spelling mistake"
],
"score": [
9
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|
lehwh8 | How do recaptchas work? And why do people need to repeat them over and over again sometimes? | Technology | explainlikeimfive | {
"a_id": [
"gmd7yxj"
],
"text": [
"Humans read text by looking at the lines on a page and seeing a pattern. We see that a straight line, no matter how long it is, looks like the letter 'L' or 'I'. We see that a line with a 'foot' at the bottom is an L. We see that any two lines with a line between them is an H. But a computer can't think like us, it can't think, 'oh, that kind of looks like other L's that I've seen, that must also be an L.' (well, they can to an extent, but it takes a lot of time and processing power, and they don't always get it right). Instead, a computer stores all of its information as a series of 0's and 1's, and if I write a basic program to display text on the screen, it's going to use one of a few common methods of converting 0's and 1's into letters or symbols. Most computers are programmed (as part of the operating system, like Windows, Linux, Android, iOS, etc.) to understand certain sequences of 0's and 1's in the same way. So if I output a bunch of characters on the screen with basic programming, then it's easy for another programmer to write some code to look for the 0's and 1's in the file that has the letters. On the other hand, if I take letters (say, 'ABCD'), and use a randomizer to swirl them around a bit and store it as an image file that the computer only understands as a bunch of dots in a rectangle (which is what you'll see in any image on a screen if you look real close), most people would still be able to read the text because they recognize the pattern. But now I can't just write a program to 'read' the text in the picture. So if I show the image on my website, I already know the correct sequence of characters, but a computer would have a more difficult time figuring out what those letters are. & #x200B; Today, regular number/letter captchas aren't 100% secure because we have better code to solve them, and there are other ways of getting around them (like sending captchas to low-paid humans to solve all day). So Google has the thing where you click images of stop signs or crosswalks or whatever, and they can cross-reference that with other people's results or what their software expects, and that's how they know if you're a human, because it's all pattern recognition that's harder for a computer to do. They use that data to help with their self-driving car company, Waymo, and probably for other stuff as well."
],
"score": [
7
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|
leiru9 | Why is 24 FPS fine on movies but horrible for video games | Technology | explainlikeimfive | {
"a_id": [
"gmdlmp5"
],
"text": [
"Answer: Motion blur, or more specifically the quality of it. When rendering a CGI movie, the computer knows everything about the current “frame” and the one before it, and what will come after it. This means the computer can accurately calculate the path of motion and simulate motion blur with high accuracy. This results in a film that looks smooth, despite not really being “smooth.” Video games, on the other hand, only know about the current frame, and only get around 16 or 33 milliseconds at 60 FPS and 30 FPS (respectively) to calculate the frame. That’s a lot less time, and means corners have to be cut. The relative lack of information about the frame means that the motion blur (or even lack thereof) is low quality, and we perceive choppiness as a result. [Edit] There’s a lot more to this, but this specifically answers the difference between film and games."
],
"score": [
9
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"text_urls": [
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|
lemk7a | what do filmography terms mean | What’s the difference between 30 frames and 60 frames per second? I’ve seen people say it becomes smoother so does that mean 60 FPS is better for fast paced video or slow video? Like what are the situations you would choose one over the other? | Technology | explainlikeimfive | {
"a_id": [
"gmfstam"
],
"text": [
"A video is just pictures shown one after another like a flip book. FPS tells you how many pictures are shown each second. [Here is a comparison]( URL_0 ) The more pictures in a second the smoother the video looks as each frame has less changes than the previous one."
],
"score": [
4
],
"text_urls": [
[
"https://gfycat.com/fearlessperfumedinsect-star-wars-the-phantom-menace-episode-1"
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lepd7q | It is my understanding that every time we are forced to use “captcha” to enter a web site, we are in fact training a computer system to recognize things. Are companies running these systems making a profit by selling this data and if so, aren’t users entitled to compensation for said training? | Technology | explainlikeimfive | {
"a_id": [
"gmgua0y",
"gmgq5vd",
"gmgzhjr",
"gmhme4g",
"gmhghe4"
],
"text": [
"Not all captchas are equal, those where you just have to read messed up text with scribbles and lines aren’t gathering any data Google has always used data to either number houses in google maps and scan books word by word, and now with the new ones where you select pictures of buses, hydrants etc, they are possibly even training for self driving cars, it’s mostly google that runs all of them, they are improving their services with it But no, just because you are helping them you aren’t entitled to get paid, they probably have something in their license agreement",
"> It is my understanding that every time we are forced to use “captcha” to enter a web site, we are in fact training a computer system to recognize things. Are companies running these systems making a profit by selling this data and if so, aren’t users entitled to compensation for said training? A CAPTCHA-system will commonly keep serving you puzzles until it is sure - to a certain degree - that you are not sending automated requests. Anything else is a side hustle at best. You are being compensated for your contribution by **being able to use the website**. There is a constant machine-learning arms race going on in the background. Bots are being trained to circumvent anti-automation measures (like CAPTCHAS) and new anti-automation measures are being developed to weed out the new bots. It's gotten to the point where the conditions for successfully \"solving\" a captcha are not only not openly disclosed but most likely not fully understood by the developers either because it's probably just increasingly obscure neural networks being fed arbitrary data streams by now.",
"Users of publicly available websites aren't really entitled to anything, especially compensation.",
"The only things you are entitled to are your basic human rights, and whatever compensation in an agreement you enter with someone else.",
"Everything you do “online” is feeding the bots. From the stuff you browse and order on Amazon, to the shows you watch on Netflix it’s all track, compartmentalized and then eventually sold. When you agree to use these products you agree that you won’t be compensated."
],
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levyt4 | How do solar panels work? | Technology | explainlikeimfive | {
"a_id": [
"gmie0uy",
"gmidqrl"
],
"text": [
"A solar panel consists of a grid of Photovoltaic cells. [Photovoltaic]( URL_2 .) simply refers to the process of converting sunlight into electric currents. The photovoltaic effect was first discovered in 1839 by [French physicist Edmond Becquere]( URL_4 ). Photovoltaic cells consist of two layers. The top layer is called the N-Type, which is negatively charged, and the bottom is the P-Type, which has a positive charge. When particles of light called [photons]( URL_1 ) hit the cell, electrons in the N-type layer get dislodged and want to travel to the [P-type layer]( URL_3 ). This is because opposite charges attract, and the electrons have a negative charge. Due to a buildup of charge between the two layers, the electrons aren’t able to simply cross over. Instead, they travel by wire from the top layer to the bottom layer. This creates a current of electrons, which is a form of [electricity]( URL_0 ), and can be harnessed in all sorts of ways. Another way to look at it is to think of the electrons as skiers traveling down a mountain. Their movement down the mountain and back to ground level is like the electron’s movement from the N-type to the P-type. Now think of the ski lift as the photons. They take the skiers back to the top of the hill, where they have nowhere to go except back to ground zero. The electrons don’t leave the system, they are simply recycled.",
"Through the photoelectric effect. When a photon hits certain materials, assuming it has a frequency above a certain threshold, it can excite an electron and grant it enough energy so that it separates itself and starts moving. Since current is just the movement of electric charges, this effect can cause a current."
],
"score": [
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3
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[
"https://www.merriam-webster.com/dictionary/electricity",
"https://spie.org/news/photonics-focus/novdec-2020/what-exactly-is-a-photon?SSO=1",
"https://energyeducation.ca/encyclopedia/Photovoltaic_effect#:~:text=The%20photovoltaic%20effect%20is%20a,convert%20sunlight%20to%20electrical%20energy",
"https://www.imagesco.com/articles/photovoltaic/photovoltaic-pg4.html",
"https://www.planete-energies.com/en/medias/close/how-does-photovoltaic-cell-work"
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