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9955j6 | How does Captcha know the solutions to all of its tests? | Technology | explainlikeimfive | {
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"For the funny looking text, the first version of Captcha would just be keyed with the answer. For the next version, reCaptcha, there were 2 words; one was like the first, a key word where they knew the answer, and another word that was scanned with optical character recognition (OCR) software from a printed work, that the OCR couldn't recognize as a word, so it was using crowdsourced labor to get an answer. The street signs one/cars one/ones based on pictures work like u/Phage0070 says: they take the most popular answers and assume those are correct, and if you differ they usually give you another one for a few iterations unless you fail too much, in which case they throw out your results and don't let you do whatever the captcha was guarding. This is basically crowdsourcing the AI that's used in self-driving cars, from what I understand.",
"It doesn't know the answers. What it does is give the same test to bunches of people and assumes that the most commonly given answer is correct."
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998big | why are loading bars inconsistent? | Technology | explainlikeimfive | {
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"To be completely honest with you, programmers don't really care about loading bars being accurate. We only put them there to stop impatient users from assuming our programs crashed, forcefully killing the process, and permanently messing up something. An inconsistent loading bar does this job just as well as a consistent one, and takes orders of magnitude less time to implement, so that's what gets used (when we can't get away with a barberpole or other infinitely looping animation in the bar).",
"Ahoy, fellow redditor. Yer not alone in askin', and kind strangers have explained: 1. [Why do the first 98% load so quickly, but the last 2% take so long? ]( URL_3 ) ^(_2 comments_) 1. [ELI5: How do loading bars work? ]( URL_5 ) ^(_5 comments_) 1. [ELI5: Why are loading bars a lie? ]( URL_4 ) ^(_5 comments_) 1. [Why does the progress bar of a loading screen or download always seem to freeze at 99%? ]( URL_1 ) ^(_3 comments_) 1. [ELI5: Why a video load bar shows minutes ahead are loaded, yet the video still pauses to buffer. ]( URL_2 ) ^(_41 comments_) 1. [ELI5:Why do loading bars usually get stuck at 99%? ]( URL_7 ) ^(_4 comments_) 1. [ELI5:Why are most computer's/software's loading bars bullshit i.e. appears that data loads in chunks and not linearly with some portions of the loading bar taking much more or much less time than other portions? ]( URL_0 ) ^(_4 comments_) 1. [ELI5: How does a loading bar work? ]( URL_6 ) ^(_4 comments_)"
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99e0t8 | How are modern day planes able to land even in thick fog? | My flight today landed in fog that reduced the visibility down to just 50 yards. How does modern technology allow for this? And why is it that some flights are still delayed due to fog? | Technology | explainlikeimfive | {
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"Depending on the plane some have auto-land systems (not joking). There’s Instrument Landing Systems that guide the aircraft down to 100-200 feet above ground. These airports usually have pretty bright runway edge lights and runway centreline lights that shine through fog pretty good especially at night. Some aircraft and some airports don’t have the systems required to do these types of approaches."
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99ed75 | Why do so many businesses still require documents to be faxed? | Technology | explainlikeimfive | {
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"As far as banks go, it's liability to their systems. When you have 10s of thousands of employees opening attachments to emails, there's bound to be something malicious eventually. You may not think so, but banks spend a fortune on technology risk. Fax receipts can be controlled easier than random PDF attachments opened by multiple persons. Also, faxes get sent to one general box that can be used for record retention. If a bank employee does not send the email to the general inbox, then there is a great possibility that it will not be uploaded for record retention. Banks are required by law to hold all documents received for a period of time. If not the fines can add up pretty quickly.",
"i had to sign a legal doc but was way way far away in another state. they faxed to me, i signed, i faxed to them. i guess they didn't have a scanner or know how to send a doc in an email. had to go to a gas station.",
"Because the laws and legal precedents regarding contracts signed by fax have been well established. This is not as true for other means of electronically signing documents, but this is starting to change If a bank is loaning someone a bunch of money, they'd rather make you take one extra step than risk screwing up the deal (and possibly losing that money) because the way the documents signed is was not considered legally valid. And if you are trying to get that loan, figuring out how to send or receive a fax is going to be one of the least difficult parts of the process."
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99exzu | In terms of computing technology such as servers and "the cloud", what happens when you play online video game which connects to other players? | Technology | explainlikeimfive | {
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"Video games are just a bunch of equations being run by computers. That doesn't change whether the game is on your console or in the cloud. If you're playing a console game, some of that processing is being done on your console and shared in real time over the internet. Those equations mix with other people's equations and the result is your game. If it's all in the cloud, it's essentially the same thing, but most of the computation is being done somewhere else. You're just seeing the outputs."
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99fa53 | How does fiber optic works? | Technology | explainlikeimfive | {
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"The fibre optic cable is made of glass in a way that traps light inside, even as it goes around corners. Pulses of light are sent in one end, and detected at the other end. The pulses can be very, very short, allowing very high data transfer rates.",
"A single fibre optic is a very fine strand of glass. It has a useful property that when a light is shone in one end, instead of the light spreading out all over, it bounces around inside the strand to the other end. So this gives you one more option, amongst the many that exist, for data transmission. It's very simple to send binary ones and zeros in a similar fashion to electrical impulses when we think of more traditional wire.",
"Put a straw in a cup of water and look at it from the side. You'll see the straw looks \"broken\" [1]. The reason this happens is that light travels through different materials (water/air) at different speeds. Which causes light to bend [2] when it reaches the \"border\" between the two materials. A fiber optic cable is made out of a flexible, clear material, usually a kind of either glass or plastic. The outer part of the cable (\"cladding\") is actually a different material from the inner part (\"core\"). Since light travels at a different speeds in the two different materials, in places where the cable isn't perfectly straight, light inside the inner part, traveling in a straight line, would normally exit the cable. But it hits the boundary between the inner/outer parts and bends. Which makes it turn back toward the inner part of the cable! Basically light is \"trapped\" inside the cable and travels from one end of the cable to the other. Which means a fiber optic cable is effectively a \"pipe for light.\" Put some kind of precision controllable light source (LED or laser) at one end of the cable, and a light sensor (photodiode) at the other end, and you have a communication system. It turns out that fiber optics are the technology behind almost every modern large scale communication system on Earth. Originally communication systems like the telegraph and telephone were built to use electricity in copper cables. But copper cables, especially long ones, tend to act like radio antennas and pick up noise from all kinds of other random electrical stuff, including other nearby cables. Which means there are physical limits to how many high-speed data carrying copper cables you can put right next to each other in a bundle. Fiber optics are just a better technology for building long-distance communication links. Fiber optics are inconvenient to work with, the receivers are a little expensive, and tearing up every street and house to replace the wiring with fiber would be super expensive. So most people get their Internet, cable TV and landline phone service by copper cables, and of course cellphones use radio waves to communicate with the nearest cell tower. But those non-fiber-optic links are just to cover the \"last mile\" from the nearest fiber optic cable to the customer's exact location. [1] [Here]( URL_0 ) is an example using a pencil instead of a draw. [2] Scientists call this bending of light \"refraction.\""
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99fhc2 | What makes a video cinematic? | Technology | explainlikeimfive | {
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"A lot more time, effort and expense it put in to each step of the cinematography process. Lighting is crucial. Movies take time to light each shot just right, allowing shadows to fall just so. TV shows will tend to be more \"light everywhere\" so the camera/actors can move without having to redo the lighting. Depth of field: Big sensors with fast prime lenses allow for a carefully controlled (shallow) depth of field. The camera is operated by a team: one of the team just pulls focus, another frames the shot. Movies use aperture to chose the depth of field. TV uses aperture to control light levels. TV work doesn't usually have a dedicated focus puller. Anamorphic lenses. The lens stretches the image vertically to maximise the amount of information hitting the sensor despite the wide screen format. This results in out of focus highlights being oval rather than round. It can also make changing focus have a weird effect to if the lens \"breathes\" when focusing (which means it zooms a bit when focusing). Colour grading + dynamic range. Cinema cameras can capture a wider range of colours and intensities and with finer steps between those values. This gives greater freedom to modify colours in post production. Frame rate and shutter time (aka shutter angle). Movies are shot almost always at 24fps and shutter time of 1/48secs. Also called 180° shutter. The amount of light entering the camera is controlled with Neutral Density filters (darkened glass) and not as much by aperture nor shutter time. 24fps is a part of the puzzle but in no way does setting a camera to 24fps instead of 30fps make the footage cinematic without taking care of all the other pieces of the puzzle."
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99gtro | Why multiple processors vs one larger processor | So these days the new generations of both CPUs and GPUs are integrating more cores/processor cores. So Why is this a better approach vs having one or just a few larger cores if multi-tasking is the concern? In my uneducated opinion, each more core introduces more over heads; and typically the more cores there are, the more difficult it is to raise the clock speed. If it's a thermal issue, the transistors can just be laid out in a larger foot print; If it's for scalability, one larger processor can still take more tasks and let different parts of itself process them if its engineering this way. Is this more a marketing scheme? Because I bet for 95% of the consumer market, 4 highly clocked cores are enough. But both AMD and Intel are pushing more cores to the main stream market. | Technology | explainlikeimfive | {
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"Processors are basically made out of silicon which is a ~~high conductive metal~~ [semiconductor]( URL_0 ) [metaloid]( URL_1 ) and as any other material, it has some physical limitations. Imagine a rubber band holding a deck of cards. You can continue including more and more cards inside but there is only so much stress you can put on the rubber band before it becomes loose or breaks. Although a loose rubber band still works it doesn't do the job properly. The rubber band stress comes in a way of stretching, for the metal on the processor that stress is heat. The faster a core is, more hot it will become, as it heats up it will loose efficiency (the equivalent of the rubber band becoming loose). And at some point it becomes really impractical to keep that core cool. So, it is way more efficient, practical and cheap to have two 3ghz cores than a single 5 or 6ghz one. **Edit:** Concept correction about silicon being a high conductive metal as /u/Qwerty_Resident pointed out.",
"In the 80-90s most of the cpu performance increase was due to making progressively smaller transistors packed closer together so signals took less time to get around, which let you make the frequency higher. Now we are at a point where making transistors any smaller makes them stop working as transistors. Now, to to make a modern cpu have more performance in the same package, you can either add more cores (complete almost independent computing units that can each do almost anything on their own), letting it do more things in parallel (favorite tactic of AMD) or make each core more \"intelligent\" (able to predict what data it will need next so it can preload things to minimize wait times, have dedicated parts that can do complex operation in one clock cycle instead of 3, etc.) > one larger processor can still take more tasks and let different parts of itself process them if its engineering this way. The parts that do this are literally cores. > In my uneducated opinion, each more core introduces more over heads; and typically the more cores there are, the more difficult it is to raise the clock speed. That arhitecture overhead is not the problem. The problem is temperature. If you increase freequency (speed), you produce more heat. If you add more cores, you also add heat, but a bit more distributed. > If it's a thermal issue, the transistors can just be laid out in a larger foot print Signals can only travel so fast without getting corrupted by interference. If you want a larger footprint, you will need to lower the frequency, or your signals inside the processor will become mainly noise. > Because I bet for 95% of the consumer market, 4 highly clocked cores are enough. Can't have 4 *highly* clocked cores on a single chip right now. They will melt without some fairly expensive cooling. Making and cooling 8 lower clocked ones is cheaper, as making them costs the same as making 4 cores. Also, programmers have gotten lazier (due to time pressures) and aren't writing efficient code like they did in the era of early computing. Plus the programs are getting more and more complicated and resource hungry, just look at windows. This means that you need to keep increasing the performance of the hardware to maintain the same level of user experience. Edit: formatting Edit2: slower code.",
"There are practical limits to single core performance: AMD and Intel both have famous examples where they focused purely on clock speed and failed miserably. The thermal issue is more or less removing hest from the package, not from individual cores. The thermal interface of the processor package is pretty efficient. Some workloads are highly capable of using multiple cores. Also, spreading out the CPU package limits clock speed due to the distance between components."
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99k5zk | Why is water cooling advertised as silent for computers but the radiator has fans in it? | Technology | explainlikeimfive | {
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"Marketing is a kind of temporary reality that ceases to exist the minute you buy something.",
"Nothing with moving parts can be silent **but** you can use multiple larger, slower, quieter fans on big watercooler's radiator to get the same (if not better) cooling you'd get from a single, fast fan on a traditional aircooling setup. It might not be \"silent\" but it's significantly less noise and, in many environments, would be covered up by the background noise. That said, a good modern aircooler with a 120mm fan is *also* going to be nearly silent. The perception that coolers are really loud is kind of dated or based on shitty stock cooling."
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99l1te | What are these 12 letters or number you often found alongside their username in online forum? Something like 24DAFA:DA4FEA. | Technology | explainlikeimfive | {
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"text": [
"Hexadecimal codes (a method of counting in base 16). Don't really know what they might represent in said forums. User ID perhaps?"
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99ncec | Why do some electronics go senile? | Technology | explainlikeimfive | {
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"Aside from dying batteries, one of the biggest causes of electronic failure are capacitors. As they get older, they can leak (both electrically and physically), which causes them to stop working properly, and possibly damage other components around them.",
"Heat cycling can crack connections over years (especially the tiiiny ones under BGA chips), and some components (especially capacitors) have contents which react or dry out over the years, reducing performance and sometimes stopping the thing from working at all."
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99t2yi | How does the film in an instant Polaroid camera work? | How does the image just appear onto the film almost instantly? Is the ink stored in the film? | Technology | explainlikeimfive | {
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"Top comment 8 months ago got 7400 upvotes: URL_0",
"theres no “ink” in a polaroid film packet. the thick bottom part of the border holds the chemicals, the rollers in the cameras burst the packet then spread it along the photo to develop it. URL_0 has a little faq section, theyre not the original polaroid company however so they talk about how their mix of chemicals work"
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99uonw | Why do airplanes get shaky when passing through clouds? | That might be false but that's just based on most of my observations in the plane... | Technology | explainlikeimfive | {
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"Think of the atmosphere like it is millions of balloons. There are pockets of balloons that are different temperatures, and the warmer ones rise to the top. Clouds have different temperatures and humidity, so the contrast is more noticeable as the aircraft passes through",
"That shakiness is called turbulence, and is caused by a number of things in the atmosphere. The first, as a few have said, is caused by air pockets (technical term in an air parcel) rising after being warmer than the surrounding air. This can happen at the surface from heating or higher up by other processes. When this happens the air may start to condense into a cloud and this would be a cumulus type of cloud. They look bubbly and fluffy when they are small. But if they are allowed to grow, by being warmer than the surrounding air, they can turn into a cumulonimbus (CB) cloud. Which can produce lightning as well. CBs forms the next type of turbulence, a gust front. Within any rain/hail/snow shower there are two sections one going up and the other coming down known as an up/downdraft respectively. The second is a response to the first (what goes up must come down). When the water or ice inside the cloud has condensed enough to form large water droplets these fall due to gravity back to the surface their momentum is imparted to the air around it and a whole column of air is descending to the surface as rain/snow/hail. At the surface the updraft and downdraft may be close to each other and this can be like driving over a hill if you are in an aircraft. One or two big shakes close to the ground, which can be dangerous if you are on final approach to land. Another form of turbulence is called Clear Air Turbulence or CAT. This can be more dangerous, as the name implies you get it within clear air so there is no obvious sign you are about to enter a patch. It is caused by a very sudden change in the speed or direction of the air flow, which you would usually find near the jet stream as that is most often the fastest air on the globe and wriggles like a snake across both hemispheres. You do have some evidence in the form of cirrus clouds, these look like wispy fingers or tendrils high in the sky and where they flick like a Nike tick that is the air quickly changing direction and we would call that cloud Jet Cirrus. Hope that helps clear it up and safe flying!",
"The air is of varying temperature and humidity, which means that some air is moveing upwards and some is moving downwards. When the aircraft passes between them, it's kind of like jumping between conveyor belts going at different speeds or different directions while running."
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99uqt2 | How come cars don't use a smaller-sized battery nowadays? | Do we really still need the big box battery to start our cars? If so, why? | Technology | explainlikeimfive | {
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"You need lots of amps, you need it to be cheap, it must widthstand hard discharge and recharge cycles and harsh environments, and, since weight and size aren’t a problem here, lead acid batteries are the way to go, since they do all of thy very well, you could make a very small li-ion pack, but it would need protection circuits and lots of cells to get those amps and it would be very expensive",
"> Do we really still need the big box battery to start our cars? Yes, yes we do. The battery turns the starter motor, a high torque electric motor that cycles the car engine until it can run under its own power. The big lead acid batteries work well for this purpose and while potentially a lithium battery might be able to do the same thing while being smaller, they wouldn't be as durable or reliable.",
"Lithium car batteries are slowly coming up in popularity. They are smaller and lighter than lead acid batteries, and last much longer. But they are also much more expensive than lead acid batteries. Since lead acid batteries are pretty reliable (sealed lead acid batteries last several years without needing a change) and since the supply of lithium is almost entirely dependent on one source (China), lithium ion batteries haven't yet become the mainstay."
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99uvk9 | When you take a picture of your computer with your phone, the screen is blurry and has weird black lines. How come? | Technology | explainlikeimfive | {
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"Screens create grids of colours to create the display that we see. A digital camera looks at a grid of points and records there colour. If they two grids are aligned, all is good. If the two grids are offset then then bad things happen: Pixels are mixed, some point on the camera sensor have very low light intensity will other have double the proper amount and lot of other problems. URL_0 \"Photographs of a TV screen taken with a digital camera often exhibit moiré patterns. Since both the TV screen and the digital camera use a scanning technique to produce or to capture pictures with horizontal scan lines, the conflicting sets of lines cause the moiré patterns. To avoid the effect, the digital camera can be aimed at an angle of 30 degrees to the TV screen.\" -Wikipedia on Moiré Pattern",
"Its the Moire effect, the same responsible for those ugly colors on thin striped shirts on tv, basically the grid of monitor pixels doesn’t line up well with the grid on the sensor, and it will happen again once you view that image on a screen"
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99w9m2 | What does non polarized phone display mean? | & #x200B; | Technology | explainlikeimfive | {
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"Light can be thought of as a wave. An electric field turns into a magnetic field and back. The relationship between these fields means that light can be 'polarized' or have all the little wiggles happen in the same direction. Polarizing filters can block out light so that only direction can pass through. Some types of screens (LCDs) and some types of sunglasses both use polarizing filters to work. But when the light coming from the screen is polarized one way and the light accepted by the sunglasses are polarized another then you see a black screen. A non-polarized screen is one with either diffusers that randomize the polarization of light after it exits the screen for lcds, or produce an image without using polarization (oleds, CRTs, VFDs, Plasmas or dlp based projectors.) because the light produced from these displays are of random polarization (the wiggles come at all angles) you can see them through polarized glasses without distortion."
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99xqfo | Why was the graphical jump from ps2 era to the next generation so large compared to what we see today? | Technology | explainlikeimfive | {
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"Same as the reason for the jump before that was bigger still. Going from black and white to colour is huge. Going from static images to moving images is huge. Going from 2D to 3D is huge. Eventually, the huge things are taken care of. Going from harsh to more natural lighting is pretty good. Going from blocky textures and models to higher details ones is pretty good. Going from foggy draw in to clear view distance is pretty good. Eventually the pretty good things are taken care of as well. The additions, while still very meaningful, become less astonishing because the cars in the driving games started to look like cars in real life a little while ago and now it's mostly just polish and finesse. Faces look a lot like people, there's still a ways to go, but they look fine. The term is the law of diminishing returns, where both in terms of power required and in terms of our own expectations, you need to put a *lot* more in to make the same kind of leaps you make going from basic to good when you're trying to go from good to great.",
"It has to do with how much we can actually notice a difference. We have gotten so high in poly count recently that increasing it doesn’t really have much of an effect anymore. The difference between having 1000 polys vs having 10000 polys is a LOT more noticeable to the naked eye than having 10000 polys vs 100000 polys."
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9a50is | How do calculator batteries never run out? | I've had the same calculator for the past 5 years and it's never died or anything, so how do they never need new batteries? | Technology | explainlikeimfive | {
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"Calculators use very little power, so it's battery lasts many years. Some calculators have a small solar panel which can usually generate enough electricity to power it - the battery is only there as a backup and so it can last for many more years without the battery going flat.",
"Well, most calculators’ shelf life last up to around ten years. But like all devices, it’s all up to how often you use it. The self discharge rate from simple calculators is very minimal, and most people don’t really use their calculators for a really long time thus making it seem like it “never runs out.”"
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9a635t | Why are industrial power generators 3-phased? Why not 1 or 2 phases, what's so special about it? | Technology | explainlikeimfive | {
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"It's like riding a bike. Two-phase power is equivalent to a two-pedal bicycle, and there are moments & mdash;when one pedal is all the way up and the other is all the way down & mdash;when pedalling is really hard and inefficient. If you had three-pedals (and three legs :-) this problem would go away.",
"If you picture a sine wave: 2 phase hit zero volts at regular inetervals. 3 phase does not. Think of it as: 3 phase is working all the time. 2 phase is not. Therefore: 3 phase is more efficient",
"Available power. With no phase ever crossing zero at the same time, you get a better delivery of constant power. NOT DC, but the availability to do work in a more efficient manner...Specially when spinning things in a circle like motors. More than 3 would nor necessarily be worth the expense, and less is just not as efficient. So like all orher good engineering practice 3 phase balances all the up-side.",
"Transmitting power over three phase is very copper efficient. If you have a single phase generator then you have two wires coming off of it(hot and neutral) which both carry the full current. If your generator is 100V and supplying 10,000W then each wire needs to support the 100 A of current. If you have a three phase generator still supplying 100V L-N then it has 3 big wires coming off of it(Phase A, B, and C) and each wire only needs to support 33A. This just dropped you from wire that is 7.3mm in diameter(1 gauge) to wire that is 3.25mm in diameter. You need 3 wires now instead of 2 but your wires are now 20% the weight of the other ones so you've saved a crap load of copper saving power companies a ton of money That's why we transmit three phase power from power stations For industrial generators and motors, the reduced current through the wire again means smaller wire, and smaller wire means more compact generators and motors which means a smaller/lighter piece of equipment that takes up less space on the floor and costs less overall.",
"There are a few answers here, but IMO none of which actually ELI5 and the ones that do, are not very good. There is so much to the actual generating of power that the inherent background needed for a full understanding is over a 5yo level. So here's my attempt (Power Industry Engineer): & #x200B; Most generator power that is created from heat is done by mechanical motion, or movement. Turning this movement into electricity by the power of magnets. To make this repeatable, this is done in a continuously moving circular motion. By doing it this way, you can continue spinning the circle as long as you are providing force to spin it. Since this act is is a circular, there are opportunities to add more magnets to push and pull on the way around. The magnets need to be sufficiently spaced so they do not effect one another and not so far that you are creating free space where the turning force is not free to spin with no resisting force for short bursts. This comes out to be about a third of a circle, so you can fit 3 magnets on the outside of a circle. There are other things to take into account such as economy of scale, existing infrastructure, design safety, cost/benefit of the materials needed, ets... & #x200B; Hope this helps.",
"With AC current, the voltage produced and the power output is not constant between any moments in time. So if you only have single phase AC current, this means whatever's hooked up to pulses on and off. So that lightbulb above you is actually turning off 120 times a second. To fast for you to see visually since the brain just sort of averages it out, but if you've a video camera with the wrong frame rate you can actually see this happening. Although some places like stadiums actually use three phase for lighting, it's how they get around that flickering when using proper slow motion cameras for replays. This is just fine for many uses, and you can split a single phase off a three phase line with a little bit of extra work, which is why the current in your house is single phase. In many other cases, this isn't acceptable, industrial motors are a common example. A single phase AC motor experiences that power pulsing on and off, just like the light does, which leads to inconsistent torque, more vibration, less efficient and needs to be run off a higher voltage (which means thicker more expensive wires in transmission) to compensate. The simplest way to get around that issue is to add another AC current into the mix, but slightly offset from the first one which gets you 2 phase AC current. unlike with single phase, [the voltage suppplied by two phase is never quite equal to zero]( URL_0 ). Where the voltage in phase A is at zero, the voltage in phase B is at a peak and vice versa. And throughout a lot of the early 20th century, 2 phase was pretty common, and you can still find it in a few places 2 phase has a few downsides however. Where single phase only needs two wires for (source and neutral), 2 phase needs at least three wires, one for each source plus the neutral, and the neutral needs to be able to handle up to 50% more current due to that point where Phase A and Phase B intersect, which means a larger and more expensive wire. You Can get around that by running a pair of source and neutral for each phase, but then you're running four wires instead of three, which means increased cost and complexity. Enter 3 phase. It turns outs that by offsetting 3 AC currents [like this]( URL_1 ) , you can create a balanced circuit without the need for a neutral wire, the other source wires can instead do this job. Which means that you can get the same benefits of a two phase system, but only using three wires, all of the same thickness. This means a 3 phase system costs a lot less to run than a 2 phase system. Infact it costs less than single phase, because you can transmit the same average power but using lesser voltages, which allows for less thick wires and conductors. We can go further and higher phase order systems have been built, (usually in multiples of three. So 6 phase, 12 phase etc), however the improvement over 3 phase is far less dramatic however they require more wire, more equipment and so on, which makes them more expensive to build. Generally speaking, the improvement is in no way worth the cost, so no one bothers.",
"3 phases is just a happy medium. Its cheap on copper, and provides the maximum return for the smallest amount of copper",
"Imagine water running thru a pipe. The more force behind the water, the greater the ability it has to, say, turn a wheel or power wash your walk. Now imagine that the force behind that water is you pushing a foot pump. Every time you push the pump the water will surge. At the initial ‘push’ of your foot, the water will be still and forced to move. In the middle of the ‘push’ the water will be at its greatest power. As your foot pushes to the floor, the water effectively stops. This action produces a repeated surge effect Now imagine that you and two friends all have a pump. As you push down, a friend is in the middle of his push, and the third friend is finishing his push. The combined effect is a contact flow with a (mostly) constant force behind it. This is three phase power.",
"There are a few reasons why three-phase power is superior to one or two-phase power. 1. **Balanced delivery of power** In single-phase power, both the voltage and the current delivered - and thus also the power delivered, assuming they are in phase with each other - go through zero twice for each cycle, i.e. a hundred times a second for the 50 Hz power typically used in Europe. This leads to for example lightbulbs flickering slightly, though it is usually not visible to the human eye. On the other hand, in three-phase power, where the three phases are one-third of a cycle offset to each other, those oscillations in voltage, current and power delivered cancel out exactly. The voltage and current both sum to 0 (e.g. when one phase is at maximum positive voltage, the other two are at half-maximum negative voltage), while the power sums to a constant value. 2. **It needs less wire** Say you have wires that can carry 100 amps each. If you want to transmit 300 amps using single-phase power, you need six wires - three live wires, and three neutral wires. On the other hand, if you have three-phase power feeding a balanced load, i.e. one that draws equally from all three phases, you need only the three live wires, as the instantaneous current of all three sums to zero at any instant and time. And even with a moderately unbalanced load, you don't need nearly as much ampacity on the return wire. 3. **It is very well-suited to rotary machinery.** If you have three electromagnets arranged in a triangle, and connect each to one phase of a three-phase supply, the sum of their magnetic fields naturally generates a [rotating magnetic field]( URL_0 ). If you now place another magnet into this rotating field, it itself will rotate. Compare this to a single-phase AC motor, which needs some special design feature to provide the rotating field on startup. You can of course also use this as a generator - make a rotor with a magnetic field rotate in the arrangement of three (or more) coils, and it will induce three-phase current in those coils."
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9a713b | How do oil powered engines actually work? | i know i can simply google it but i cant make it go inside my head and understand it, how a simple liquid powers up an engine just by pouring some oil on it, why others liquids like water wont power it up. | Technology | explainlikeimfive | {
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"Well fuel cells work with water, but that is a different discussion. Basically oil explodes when you light it on fire. You light it on fire by giving it a spark or compressing it really fast. When it explodes it gives of heat. If you have taken a chemistry course you may remember the ideal gas law: Pressure x Volume = nRTemperature. If you make Temperature go up then volume goes up too. That pushes a piston when turns the wheel. So basically you explode tiny amounts of flammable liquid and the heat makes gas expand, and that expansion turns the piston which turns the wheels. They get big and fancy with multiple cylinders and a lot of gears, but that is basically it.",
"Because oil burns and water doesn't. The bonds joining atoms of hydrogen and carbon in a fuel molecule aren't very strong. On the other hand, the bonds between the atoms of hydrogen and oxygen in water and the carbon and oxygen in carbon dioxide are very strong. When you burn something, you spend less energy breaking down hydrocarbon and molecular oxygen than you release by creating water and CO2. The released energy is what powers the motor."
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9a9dx7 | Why are TV applications so slow? We have tiny smartphones with super fast processors, so why are these not matched in Smart TVs? | Technology | explainlikeimfive | {
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"I think there are a couple of factors. 1) usually anyone who can get a smart tv has some other box that does these things better, therefore 2) not putting a top-of-the-line chipset in a TV cuts down on cost and allows them to sell panels for a cheaper price tag, and 3) if someone can't afford having a different box for that stuff, they usually don't mind having something that just works. That's my guess.",
"The processor and the network adapter onboard most Smart TV's aren't top shelf to start with. Then the manufacturer has to source an application to run on their platform. Actual application performance isn't prioritized, it just needs to 'work'. These things combined makes for the mess that are Smart TV integrated applications. In short, limited hardware resources and a lack of optimization are the culprit."
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9a9nb0 | what is "The "Cloud" and how is it different than the internet? | Technology | explainlikeimfive | {
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"Back in the day, we used to just call it a “server”. Or “remote host”. Then, a few years ago, somebody invented this cuddly term to appeal to the common man.",
"The Internet is a global, connected series of networks that share common communication protocols. In it's most simple sense, the \"Cloud\" is used to refer to software and data that resides somewhere else on the Intenet _other than_ your personal computer (if you're an individual) or physical servers that you manage yourself (if you're a company). So, for example, do you have Microsoft Office installed on your computer? Then that's not in the cloud, because it's installed on your personal computer and that's how you access it. Google Docs? Cloud! Because the software and even the data is _not_ stored on your personal computer but on servers owned and managed by Google (although a _copy_ might be stored locally on your computer). EDIT: It does get a lot more complex than that. When someone talks about \"cloud computing\" they're usually not talking about software, but about services that allow you to rent or lease entire computers that are \"in the cloud\" (i.e. accessed only via the Internet). You've heard of Amazon Web Services (AWS) or Microsoft Azure or Google Cloud Compute? Those are cloud computing services. Instead of purchasing and managing a bunch of servers to build software on, companies will lease those servers and infrastructure from AWS or Azure or Cloud Computer and access them remotely over the Internet. But wait! It gets even more complex! Because when you lease a server from, say, AWS, you're not actually leasing a _physical_ machine, you're leasing a _virtual_ machine. A virtual machine is an operating system that runs inside of software that mimics hardware. This is important for companies like AWS because they can have multiple virtual machines running on a single real, _physical_ machine. All of this is super-important and crucial to how online software and services are provided these days. Giant, wealthy companies like Amazon, Microsoft, and Google are making the investments in the physical hardware and infrastructure and leasing access to servers (virtual machines) on their hardware and infrastructure to other companies who use that to build their own software and services. In the past, companies needed a lot of money up-front (aka capital) to get started, because they had to buy hardware and infrastructure to run their business. Cloud computing _drastically_ lowers the cost of entry for start-ups, because companies don't need capital to get started. Since they can lease just what they need from Amazon, Microsoft, or Google on a monthly basis, _much_ less money is needed to get started. Lower costs of entry means more software and services, which means more demand for cloud computing, which makes Amazon, Microsoft, and Google even richer, so they can buy more hardware and infrastructure."
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9a9t94 | How do the calorie counters work on things like treadmills? Are they accurate? | & #x200B; | Technology | explainlikeimfive | {
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"They're ballpark estimates based on average weight body shape person. So no, they're not accurate",
"If you're inputting your weight, they're accurate enough. Calories are a measure of energy, and the treadmill can calculate the amount of energy it takes to move a body of a certain mass a given distance. Using this, it's certainly enough for calorie counting and decent estimations.",
"They work by knowing how much energy you need to run at whatever pace you’ve set, for however long it’s been active. They are never going to be 100% accurate, but they’re very close (especially if it also asks you for weight info)."
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9acif8 | Why does a 4k video on a 1080p screen looks better than a 1080p video on a 1080p screen? | Technology | explainlikeimfive | {
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"Supersampling and antialiasing. the idea behind that is that is this, imagine you have a straight diagonal line on the screen that you draw pixel by pixel, since the pixels have a finite size there will be points where the line will jump to the next row. The line will look like a saw blade. Now if you take the same line but draw it in 4 times as many pixels (well call then subpixel) you can make a finer saw blade to represent the line but since your display can only display 1/4 of the subpixels you used to draw that line you need to decide on how to do it. The simpler way is to average the values of each 4 subpixel block. You will get a line that will bleed into some of the pixels that didn't have a line on the first example but the overall effect is that the line will look nicer and less like a saw blade. I hope this was a good explanation. It is simpler to explain using diagrams but I'm too lazy to search them.",
"Are you talking about streaming video? The bitrate is higher for 4K content. Youtube for example, uses a kinda low bitrate for 1080p that doesn't work very well for all types of content."
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9ae596 | Why do companies like Verizon work so hard to limit customers internet usage? | Technology | explainlikeimfive | {
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"Money. They don’t want to invest in infrastructure so they throttle customers to save costs.",
"I switched to T-Mobile over 55 plan in March, and immediately both my phone and my daughter's got 100% locked out of youtube, Amazon Prime Video and Netflix. Everything else works great (Pandora, Amazon Music, Spotify). Even when you got URL_0 , it doesn't load. (and I am getting creeped out that most of the times I have posted this, I get downvotes making me think T-Mobile has people monitoring Reddit, but obviously not sure about that) ** EDIT ** 1) For those who have said that I should contact them -- > I have contacted them. I spent hours in April, gave up then this week I started again and have been on the phone for hours. They are going to call me again on Monday. 2) For those who said their T-Mobile works fine, so did mine, it was amazingly good until the instant I switched to the 55 plan. Then all of a sudden both my phone AND my daughter's phone lost Youtube, Netflix and Amazon Prime Video (amazon music streams great btw) More detail: The original call was a farce. 1) Switch out the SIM card. Okay, really? Both my daughter and I lost Youtube the instant we switched. It works on Wifi. In the history of SIM cards has there ever been one single instance where the SIM card was corrupt causing just 3 APPs to not work, and on two separate phones on the same plan at the same time? 2) Reinstall youtube. Really? It works amazingly well on Wifi, AND I can't even reach URL_0 in any of the browsers on my phone. Doesn't sound like the APP is the problem.",
"There are a few ways to answer this. In the USA, the system and laws are set up a certain way. Basically, they only have so much bandwidth to go around, and they've found they make more money by telling people it's unlimited then throttling later, rather than giving an accurate assessment of how much you get. So that's what they do. By throttling, they can provide a higher average speed to everyone (who isn't getting throttled), and charge extra to people who are getting throttled. It's basically just a way of getting the most money possible out of a finite resource, and continues to be true if we're on 1mb/s connections or 1gb/s connections. The system is set up in such a way that allows them to do it, and they make more money that way, so they do it. To put it another way, the system is set up such that the more they screw people over, the better their company does. In the UK, ISP's have hard, enforced limits on truth in advertising and aren't allowed to do such things, so they don't. They tried to get around it by selling \"Up to 50mb/s\", but that was recently outlawed as well, so what you see is what you get. Also the UK has a higher population density and laws again monopolies in utilities, so they have to compete against other companies. They still try to screw people over, but the law limits the number of ways they can do that, and limits the rewards. This makes a strategy of complete screwing over less profitable, and in some cases it even provides less added value than the goodwill of acting in good faith. But that's another story. I'm simplifying here, and there are other differences besides between the countries. But the basic rule is, if a situation is set up which incentivises a certain action in a global economy, companies will take that action.",
"To reduce there cost and income and incrase profit. Data usage in mobile networks cost money. It is not the cost to send the data as the only cost then is a small around of electricity usage. The cost is to have enough capacity. A cell tower like any other communications system have a max bandwidth So if many people use more data the max capacity is reached and you need to build add more cell towers to give the users the ability to use the network. So it cost a lot of money to increase the amount of data the network can transmit. So if you reduce data usage you can have more customers in the same network and the result in higher profit. The other part is they like to sell more expensive contract. So even if the network is not congested if you can get people to pay more you get higher profit. You have to compare both parts with the risk of consumers moving to another cell phone provides so increased price or reduce data can result in that you loose more customers and the result is a decreased profit so what operators do depend a lot of the competition on the market.",
"Imagine you are a cell phone network provider. You have a number of towers to service a number of customers. These towers cost money. They are assets that depreciate, they have equipment that needs maintenance, they require electricity and the upstream bandwidth needs to be paid for as well. Additionally, the FCC in the USA leases bandwidth out to network providers in an auction process, so you've paid in advance for that bit of spectrum you're going to use as well. You also have sales, general and admin costs, like any other company. This asset of a network costs money to run, so it is your job as a cell provider to extract the maximum value from your customers for your whole network. (That's capitalism.) This is why cell providers charge extra for services like picture messaging (in the UK at least, almost everyone probably uses Whatsapp or other services nowadays.) They know the few customers still using those services will pay extra to have that. If you have only so many customers in a given area and if all of them started using 1TB per month you'd have to install many more cell towers and bid for more bandwidth to make this viable. As a result, you'd have to charge a lot more money per customer.",
"I know the reason, but wouldn't it be wonderful if you still got a few MB/s even when you go over, and then they start the Chinese water toture of kilobytes after you double your \"data cap\" on your UNLIMITED FUCKING PLAN?!",
"If you control the supply you can charge what you want - I.e debeers have loads of diamonds but only release minute amounts so they can charge more",
"Its called a contention ratio. The idea is that the customer wont use 100% of their pipe 100% of the time. So the pipe serving your area/telco isnt customer pipe x customer number, its customer pipe x customer -50% or whatever ratio they can get away with.",
"Why should I pay the same as someone who watches netflix every day?",
"People are forgetting Verizon and other larger cell companies sell celltower usage to smaller companies and prepaid services. So not only are they saving costs, they're generating more revenue to allow other smaller companies piggy-back off their towers where the smaller company has no coverage."
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9aekn3 | how does signing something with PGP confirm the authenticity | Technology | explainlikeimfive | {
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"In regular cryptography, you use the same key for encryption and decryption. If that key is compromised, you can both create and read all the messages made using it. With a public key system like PGP uses, there are two keys, one to encrypt and one to decrypt, and knowing one doesn't easily let you figure out the other. One key is called the public key, and that is widely published, and the other is the private key, which is kept secret. If you want to send me a message, you look up my public key, encrypt, and the result is a message anyone can make but only I can read. It works the other way, too. If I encrypt a message with my private key, the result is a message anyone could read, using my public, but only I could have written. That's one way to create a digital signature. What's cool is we can use both at the same time. You create a message, encrypt it with your private key, then encrypt it again with my public key. The result is a message only I can read, and only you could have written."
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9aenm2 | What is Geofencing? | & #x200B; | Technology | explainlikeimfive | {
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"The wikipedia page explains this well : > A geo-fence is a virtual perimeter for a real-world geographic area.[1] A geo-fence could be dynamically generated—as in a radius around a point location, or a geo-fence can be a predefined set of boundaries (such as school zones or neighborhood boundaries). > The use of a geo-fence is called geo-fencing, and one example of usage involves a location-aware device of a location-based service (LBS) user entering or exiting a geo-fence. This activity could trigger an alert to the device's user as well as messaging to the geo-fence operator. This info, which could contain the location of the device, could be sent to a mobile telephone or an email account. So, basically, a geo-fence is when instead of installing a real fence, you program a computer to tell you if you're inside or outside the fence.",
"One everyday use for this technology is in WIFI thermostats. You link your mobile phone to the thermostat. Then when your phone is far away enough from your home, the thermostat will lower the heating set point or raise the cooling set point. Works in reverse when returning home. There is a state government energy savings program where I live (Wisconsin) that offers a $75.00 rebate for a thermostat that has geofencing.",
"If you have the Starbucks app they are a good example. Close to a Starbucks? Get a notification that you should get Starbucks."
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9aeptg | How does the internet work so insanely fast? | I'm an IT student and I don't understand this shit. If I ping [ URL_1 ]( URL_0 ) from Australia it takes 240ms to go from my computer to Sydney to Tokyo to somewhere in Taiwan I think and back again. It has 16 "stops" between me and the destination. Doesn't something have to happen at each of the "stops" that would take time? I can't wrap my head around how fast the internet is. | Technology | explainlikeimfive | {
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"There are two parts to this: how long it takes the signal to travel the physical distance involved, and how long the \"routing\" takes (the logic needed to decide where to send the signal at each \"stop\". More commonly known as a \"hop\", I believe, by the way.) **Transport (100 msecs)** The first part is pretty straightforward: Sydney- > Tokyo- > Taiwan- > Tokyo- > Sydney is about 20,000 km. Most of this is via [undersea cables]( URL_3 ), where light travels \\~31% slower than in vacuum, so that's a minimum of 100 msecs just to push those shitty ~~electrons~~ photons from point A to point B. (Edit: To clarify, the speed of light is slower because [undersea cables use fiber-optic lines]( URL_2 ) \\- i.e. really long glass strands - and the speed of light is slower in glass than in air or vacuum. It has nothing to do with the cables being in/under water.) Note: Some data may go via telecommunications satellites, but these orbit anywhere from 2,000 to 35,000 km above the earth, so involve greater distances = more time. **Routing (140 msecs)** The second part, routing, is a little more complicated. Basically there are three \"levels\" to the internet: [Access, Distribution, and Core]( URL_0 ). For an ELI5, we can just say the hops you're seeing all take place at/between these levels, each of which involves dedicated hardware specifically designed to make receiving, processing, and retransmitting of data as fast as possible (especially at the Core layer). Still, this part takes a significant amount of time. Edit: ... and I'll refer you to /u/MavEtJu's [answer]( URL_5 ) for details of what's involved here. **Commentary** Empirically, what you're seeing is that the routing portion of each of those 16 hops takes 140ms in total, or \\~9ms each. That may or may not seem like a long time, but consider that a modern quad-core CPU can perform \\~100 million operations in that 9ms. And that's for a general CPU. Network hardware is using purpose-built chipsets more akin to graphics processors (i.e. optimized for specific logic w/ high throughput), which can do 100x that. Surely such fast hardware shouldn't take that long... right? Well, consider the amount of data involved. Your data packets are travelling along the backbone of the internet where a *tremendous* amount of data has to be processed. For example, there's a Hong Kong- > LA cable that does [144,000 gbps]( URL_1 ). Even though your packets may only take a nanosecond to deal with, they have to wait in line (buffer) while the ones ahead of them are dealt with. P.S. Check out the [mtr]( URL_4 ) CLI (requires install). It's `ping` \\+ `traceroute` on crack.",
"> It has 16 \"stops\" between me and the destination. Doesn't something have to happen at each of the \"stops\" that would take time? Yes, and that is where the 240 ms also comes from. There are several factors on the time-\"distance\" of a remote site: 1. Speed of light in a fibre is about 200 Mm/s, 2/3rd the speed of light in a vacuum. So every 200 meters takes one microsecond. From Sydney to Melbourne, about 1000 km, takes 5000 microseconds which is 5 milliseconds. There is nothing you can do about this, this is just a speed of light limitation. 2. Serialization delay, the time it takes from a serial signal into a parallel signal. For your 1 Mbps ADSL link takes 12 ms to convert the 1500 bytes of an IP packet in memory to go out of the ADSL modem onto the copper wire. 3. At every stop the IP header gets inspected to find out if it is still valid (TTL > 0, checksum okay) and where it needs to go to (IP destination address). Its TTL gets decreased and the IP checksum gets recalculated ( < --- major stupid idea in the IP protocol, the TTL should have been left out of the checksum, IPv6 doesn't have one). After inspection it gets put in the right outgoing interface and waits there to be transmitted. You have here queueing delay and yes, serialization delay again. So between hops you have the speed of light delay, and at every hop you have serialization delay and recalculation delay. The speed of light delay is relative large, serialization delay is large at slow links but the recalculation delay is minimal. The queueing delay is hopefully none if the network is not congested. Now why is the total of these numbers still well below one second? Because fibre links are fast, serialization delay is minimal on fast links, the routers at the hops are fast and there is no congestion.",
"To put it into a bit of perspective computer processors run at GHz speed. A 1 GHz frequency is equivalent to a 1 ns time period. 240ms is 2.4x10^8 ns.",
"Light is super fast. The actual fastest you possibly ping URL_0 is around 80 ms (Australia is about 8000 miles from Redmond, Washington, or 40 ms at the speed of light).",
"Light and electricity move *very very very very very very very very very very very very very* fast.",
"Modern switches and routers use ASICs (Application Specific Integrated Circuits) which are basically circuitboards arranged cleverly to perform the same calculations (with different input numbers) over and over again. The trick is that because it's a circuitboard with no moving parts or anything, the calculation is performed as quickly as the electricity flows through the wire. If you imagine having to do the same calculations all day every day you'd try to come up with a clever way to do it. Also each router on the way talks to all of its neighbours about what other routers it knows. With this, each stop also figures out the shortest path to get to where you want it to go. With fibre cables under the seas and underground connecting countries and cities together the data can move long distances at the speed of light. So to put it all together when you ping URL_0 . Your computer sends a packet to your router, your router doesn't know how to get to microsoft but it trusts your ISP does so it sends it out. (probably over copper cables so moving at the speed of electricity) Your ISP knows how to get to Microsoft so it sends it to the next router along the path which (for the sake of example is on the coast and uses these undersea cables) sends it out over fibre-optic cables to the next router and so on and so on until it gets to Microsoft. The calculations on each router will take nanoseconds. The basic reason it's so fast is because clever people made it fast.",
"Short version: Akamai Technologies, Inc. As users have pointed out explaining how an actual exchange (and end user visiting a website/app, and the steps that take place), the OP asked how does it work \"so insanely fast\". The reality is that BGP routing protocols do not pick the fastest route possible when traversing the internet, so companies like Akamai created (essentially) an overlay to the public internet that routes traffic efficiently, with the end user's best experience in mind. Everything else was not ELI5.",
"Your toy is in the corner. It takes 10 steps to get to the corner. each step is easy ‘cause you already know how to walk and where to go. It’s a pretty simple task. Each step takes one second so you’ll have your toy in 10 seconds! Now replace seconds with ms. Your toy with data. And your body is a fiber optic transmission running at the speed of light. Each step is a gate where your brain takes literally 1 nano second to process your current task and re-route via http/2: a highly specialized vehicle for moving your request around that everyone can understand. At the speed of light going from beijing to New Orleans (+7000mi) would take roughly 40ms. Add in sometime for all the other stuff. If you have windoz run cmd and type: tracert URL_0 You’ll see exactly how it works."
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"http://www.mcmcse.com/cisco/guides/hierarchical_model.shtml",
"https://spectrum.ieee.org/telecom/internet/submarine-cable-goes-for-record-144000-gigabits-from-hong-kong-to-la-in-1-second",
"https://en.wikipedia.org/wiki/Submarine_communications_cable",
"https://www.submarinecablemap.com/",
"https://www.linode.com/docs/networking/diagnostics/diagnosing-network-issues-with-mtr/",
"https://www.reddit.com/r/explainlikeimfive/comments/9aeptg/eli5_how_does_the_internet_work_so_insanely_fast/e4uxfxm/"
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9af4va | How do they come up with thousands of puzzles for puzzle games? | & #x200B; | Technology | explainlikeimfive | {
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"Usually by finding a theme that can be varied a bit in multiple ways and then building suites of related puzzles, which also lets them implement difficulty curves. Also, there have been countless puzzles already invented, some very classic. You can get a lot of your work done by researching."
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9agccu | What happens if you take your phone off of airplane mode on a plane? | Technology | explainlikeimfive | {
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"text": [
"Nothing. It's just that they want to minimize any potential risk of interference from 100+ cell phones on the plane. Even then, most of the electronics of the airplane are pretty well shielded against things like that."
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9agcvq | How are the raw images sent back from space probes processed in such a way to give a vibrant and colourful image? | Let's use Saturn as an example. [This is a raw image from Cassini]( URL_0 ), and [this is a processed image]( URL_1 ). Additionally, if I was to jump in a space ship and fly out to Saturn, would it look like the second image? | Technology | explainlikeimfive | {
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"Cameras aboard spacecraft like Cassini take photos using filters that isolate different wavelengths on the electromagnetic spectrum. Some, like red, green, and blue, capture light the human eye can see. Others, like ultraviolet and infrared, capture light it can't. All the images arrive to Earth as black-and-white frames, and then are assigned colors digitally and compiled into a composite. Sometimes the composite is a false-color image, where colors may be assigned to show infrared or ultraviolet that we normally can't see with our eyes. Others may be composites of visible light plus infrared and/or ultraviolet. The second image you linked happens to be a true-color composite, although it may be edited to make the colors pop a bit more. If you hitched a ride on Cassini, that image is more-or-less what you'd see with your own eyes. With a decent backyard telescope you can see Saturn with the same colors, albeit a lot smaller and in not nearly as much detail.",
"Yes and no? Look at the pictures of Pluto. This is the best example. The data sent back is a mix of things that are then assigned colors. Also, in the case with Pluto the colors are there but very faint so they bump them to show the chemical, geologic, and physical attributes of the planet to show it's structure, composition, etc... If we jumped in a ship and drove to Pluto it'd look bland. Very faint greys and blues, maybe some copper but overall it's sepia toned. So to make it look interesting they pump up colors. there's Panorama pictures from Mars that show you what it would look like under Earth-like lighting conditions but also what it looks like under Mars's sky. This makes it a nice image and also clearly shows the attributes I mentioned. These are \"~~falls~~ false color\" images. True color images aren't as visually impressive. Not to say that's why images are colored falsely, all three image types are out there. TL;DR: Space agencies will use false color to show different data to illuminate features that naturally would not be seen. Visible spectrum pictures are also created via different data."
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9ahdub | Why do self-checkout machines sometimes need “assistance?” | Technology | explainlikeimfive | {
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"text": [
"Sometimes the customer operating the self-checkout don't follow prescribed steps, so the machine calls for assistance. For example, not placing a scanned object in the bagging area without indicating that you are going to skip bagging will call for assistance. Or because a customer scans a restricted item, like alcohol, that requires an ID check. Or scanning an object and want it removed will call for assistance to ensure that the item isn't being removed from the purchase, but stolen along with the paid items."
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9ai0sx | If a person on TV is talking to someone across the country/world why does it take seconds for the other person to respond when seamless video chat over internet has been a thing for year? | Technology | explainlikeimfive | {
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"text": [
"In these cases, it's because they are talking via *satellite* instead of fiber-optic Internet connection. Communication satellites are so far from Earth's surface that there's a noticeable delay."
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9ak3x9 | Why do the machines at the laundromat occasionally reject my quarters? | Technology | explainlikeimfive | {
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"text": [
"Machine senses what type of coin based on it's weight. Machine is designed for heavy use not 100% precision. Quarter weight is inaccurately measured first time so it's rejected, put in again and is measured correctly, you get clean clothes."
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9al5ga | How are modern day CPU's or GPU's designed? | Technology | explainlikeimfive | {
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"text": [
"There is a circuit programming language called [VHDL]( URL_0 ) (VHSIC Hardware Description Language -- VHSIC stands for Very High Speed Integrated Circuit but sometimes the 'v' referred to Verilog in the past) that allows digital circuits to be designed in code and simulated in operation in computer simulation. VHDL descriptions of circuits can --if relatively modest in scale and performance-- then be loaded into Field Programmable Gate Arrays or Application Specific ICs that simulate the circuit for testing in hardware. FPGAs are like a set of generic logic gates that can be programmed by a companion Programmable Read-Only Memory array. ASICs are similar but, like usual Read Only Memory, can only be programmed once. This coded design description can then be entered into Electronic Design Automation systems that take the VHDL code and generate the geometric patterns that correspond to the physical shapes of semiconductor materials that are deposited on each layer of a silicon wafer. These drawings are then miniaturized, duplicated, and printed into 'masks' for the actual deposition on silicon wafer in various processes that are similar to screen-printing or generally called 'lithography'. VHDL is also used with FPGAs to make 'virtual computers' where simulated circuits function as programs, doing most of their operations in one clock cycle. This has been used to make custom co-processors for scientific work, but requires a conventional companion computer to program the FPGAs. It has been proposed that --when we reach the limits of Moore's Law with traditional microprocessors-- whole general purpose computers may someday be based on this, using self-addressing dynamic gate array devices that translate programs into temporary virtual circuits. This is similar to the electronics described in Star Trek canon and what various futurists refer to a 'computronium'."
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9aoqsy | How does Strict NAT and UPNP affect online connectivity while gaming? | Technology | explainlikeimfive | {
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"NAT or Network Address Translation is basically a way for your router to handle translating private/local IP addresses (192.168.x.x/172.16.x.x/10.x.x.x) to public addresses. Without it, each device on a local network would either need a public IP address, or would not be able to communicate with devices outside its own subnet without some other comparable wizardry going on. UPNP or Universal Plug N Play is a way for a device (almost always consumer) to automatically configure itself and other devices on the network (sometimes routers) for purposes of application-specific communication. There really isn't a \"strict\" NAT or UPNP. Modern online gaming really doesn't require any special configuration, as you're typically establishing an outbound connection between yourself and a server (which bypasses any inbound firewall restrictions), as well as any other players and the server handles the client to client communications. NAT still exists but it's seamless from the user's perspective and UPNP isn't extensively used anymore. Back in the day, you might directly communicate with other players in online games and thus port forwarding would have been required on your router (Both due to NAT and inbound firewall rules, which are basically \"Deny anything I've not explicitly told it to accept\") to forward traffic on the appropriate port to your computer, assuming this wasn't handled by UPNP if the application and router both supported it."
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9aqd2t | How does the EAS (Emergency Alert System) work? | I tried reading about it on Wikipedia but I end up in the “Wikipedia Loop” because everything is so technical. Anyways I’m wondering these: - Who send the message? - What is a SAME header and how is a EAS message composed? - Who receives the message before us? - How do we receive the message? - What’s with the odd tone we hear | Technology | explainlikeimfive | {
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"> who sends the message? The united states gvmt requires all communications (radio, TV) companies to be connected to the government and capable of transmitting the EAS signal. > what is a SAME header? A SAME header is a standard way for the EAS system to tell any system listening to a broadcast that there's an emergency. It comprises information about which areas are affected, where the message is coming from (president, national agency, local authority, etc..), what's happening, and how long this might go on for. This allows receivers to tune out messages not meant for the area they are in. Any receivers in the area will respond to an emergency signal by turning the volume up. An uncomfortable tone will sound for a while, and then whoever needs to communicate the emergency can broadcast audio to the receiver. > who receives the message before us No one really. The radio stations will receive the message from whoever broadcasts it, and will repeat it out in real time over their transmitters > what's with the odd tone There's the initial SAME header, which is repeated 3 times just in case. Most receivers will understand it the first time and turn up their volume, allowing the listener to hear the next two SAME packets. This is in itself uncomfortable, like a dialup sound. Then the system produces the horrible noise you hear. This is designed to be uncomfortable or unsettling to attract the possible recipient of the message.",
"In the US, the FCC requires anyone who receives a radio or TV broadcasting license to participate in the EAS. It allows governments to break into programming go to provide emergency information. > Who send the message? Various parties can initiate the message, include the president, state and local governments, FEMA, the National Weather Service, or the broadcasters themselves. > What is a SAME header and how is a EAS message composed? The header spells out the nature of the message, who sent it, and what areas are affected. If a TV station in North Dakota gets a hurricaine alert, the information in the SAME header tells them they don't need to broadcast it. The rest of the EAS message is text or audio. > Who receives the message before us? For high priority messages, no person does, they are sent and automatically break into the broadcast. For lower priority messages, the station might review them first and decide when and how to relay them. > How do we receive the message? Via radio, TV, and if you opt in, your mobile device. > What’s with the odd tone we hear It is an alert signal that identifies an emergency message will follow. It serves the same function as a siren on an ambulance, something distinctive, easily recognized, and unlike to be mistaken for something else."
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9ar1yl | why do cell phones' internet work outside or in the car but not laptops'? | Technology | explainlikeimfive | {
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"text": [
"Cell phones use a data connection through cell towers, while laptops use wifi that needs to connect to a wireless router connected to the internet via an ISP (Comcast, etc.).",
"Different transmitter/receivers. You can get a usb adapter for a laptop that will use cell signals."
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9au923 | Why did in the past using the phone disconnect you from the internet? How did we get past this problem today? | Technology | explainlikeimfive | {
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"text": [
"Today we know phones as personal appliances. But before they were, phones were household appliances. A single line for one or more phones in a house to share. It was over this phone line that people first started getting on the Internet, using a modem to transfer digital information over the analog line. But only one person can use the line at a time, so if someone else picked up a phone in the house while someone was online, it could easily knock them offline. We have gotten around it by no longer using the voice landline as a way to get on the Internet. Most people get on through cable modems, DSL (which goes over the same physical line as a landline phone but on different frequencies so they can both work at once), or cellular connections. Very few people use landline phones and modems today.",
"In the past most people connected to the internet via a telephone modem. The modem used the same line as the phone, so you couldn't use both at the same time. Most people now use dedicated internet lines (ADSL, cable, or fiber), but that wasn't very common in the 90s.",
"In the past, the internet was accessed using something called \"dial up internet\" which was exactly what it sounds like. You computer was calling a phone number. Instead of you using a phone to call another person on their phone and talking with your voice, your computer used a modem to call another computer with its modem and talked using a series of tones and beeps. It couldn't work at the same time you used your phone to call someone for the same reason you couldn't have someone else in your house make another phone call from the same line. 1 phone line=1 conversation with someone/something else, whether that's a human talking to a human or a computer talking to a computer. Just like how you could pick up a second phone in your house and hear a family member on the phone if they were using it, if someone was on the internet you could pick up the phone and hear the computers talking to each other. That's what those loud hisses and pops and screeching were. We got past it by using a different sort of technology to access the internet. DSL, which also uses phone lines but does it in a way that it doesn't occupy the part of the phone that human voice goes over so it doesn't cancel out phone calls, cable internet which uses the same connection as cable TV, satellite internet which uses a dish to talk to a satellite directly, fiber optic internet which uses a completely different sort of connection(cables that carry light) instead of piggybacking off of something you already had like cable or phone, or cellular internet which uses the data connection of cell phone towers."
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9aum21 | How air conditioning and refrigerators cool the air. | I've been thinking about this too much recently. So normally to cool something you need something else that is already at a low temperature. So how does air conditioning and refrigerators cool air without ice or anything cold to begin with? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Basically it takes all the heat and throws it out of the room/refrigerator. This is why a refrigerator is warm on the back, as this is where the heat comes out. Same with the air conditions, The absence of heat results in cold.",
"Ever used a can of compressed “air”, like for cleaning out a computer? Notice as the pressure drops, and the liquid inside becomes gas, it becomes cool? The expanding gas absorbs heat (energy), resulting in cold (absence of heat). Compressing that gas releases the stored energy (heat). Air conditioning and refrigerators work on the same principle. In the air handler inside the home, the liquid is allowed to expand into gas in a radiator and absorb the heat of the interior air blowing over it. The now warmer gas flows down to the outside unit where the compressor, compresses the gas back to a liquid and runs it through another radiator with air blowing over it, to blow away the heat that was collected indoors. The effect of this is that it moves the “hot” in the house, to the outside. When you look at window ac units or the outside compressor of a home, the silver colored fins that are often smooshed by people, that’s the radiator that is responsible for removing the heat as that fan blows air over it. Heat pumps are the same thing, but, can also work in reverse. They take heat from the outside air and move it inside in winter time, and in summer, they take heat from inside and move it outside."
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9avd31 | Why movies are shown in < 60 FPS | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Customer preferences typically go to a lower framerate with slightly blurred motion, although nobody has really tested higher framerate films in a widespread commercial setting for a long time."
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9awt2k | What parts of a computer language make it "best" for this or that situation? | Technology | explainlikeimfive | {
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"text": [
"There are always tradeoff between ease of use and expressivity. If you want to be able to do more specialized things, you need more buttons in your craft. But then it's harder to use it. There are also problems with compatibility in different OS (looking at you microsoft). Finally, sometimes you want other paradigms. There are language where you write what's true, rules, and the computer infers what else is true. This is so different from «normal» programming that no language pretending to do both could be easy to read.",
"Well, each individual language has their advantages and disadvantages, so it's indeed a bit of a whackamole situation. But you can basically split them up into three categories: **imperative** (think C and later, Python; the \"classic\" approach), **object-oriented** (think Java, C#; the \"modern, user-friendly\" approach) and **functional** (e.g. Haskell; the mathematical approach). Imperative languages are generally practical for very complex/long-term running projects, because they are very structured and easy to follow once you get used to the style, which makes for good maintenance. You pretty much straight up tell the system what you want it to do. They're also a bit of an allrounder. Object-oriented languages are very popular these days and are easier to grasp if you are new to programming, good for smaller projects and projects that mirror scenarios in the real world, like games. There's tons of tutorials on the interwebs for OO programming if you want to dig further. Functional ones are... well, as the name suggests, most of the syntax of these languages consists of mathematical functions. You don't assign variables like in other languages, but rather string functions together to process the input (whatever that is) in a meaningful way. Not very beginner friendly if you're not that into maths, but it can potentially simplify very complex mathematical tasks because you don't really have to cast them into code like you'd have to with imperative or OO languages. (Also shoutout to Haskell's \"lazy evaluation\", but that warrants its own ELI5.) Keep in mind these are no hard limits, you can do pretty much anything in any language you want if you're invested. You specifically mentioned database interactions. These typically have their own addressing languages depending on the database (SQL and MongoDB being prime examples) which you use as \"plugins\" in your project, the setup is different depending on what you're coding in."
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9axyil | How does a computer understand code? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"**TL;DR A program called a compiler translates the code into machine code, which the computer is hardwired to understand.** The computer doesn't understand code. It understands machine code - instructions that are encoded in binary - because it is hardwired to do so. For example, if it reads an instruction that begins in the bits 00000100 then it is hardwired to perform an addition operation. In the past, computer programs were written directly in machine code - a human programmer would translate the instructions on paper to binary, and would feed that binary to the computer. The next step was a language called Assembly. Assembly is a human-readable representation of machine code - each assembly instruction was directly translated into a binary instruction. Programmers wrote an Assembler - a program that takes the Assembly code and translates it into machine code, making it much easier to write programs (you no longer have to write bit after bit, instead you could write actual instructions). Next up came high-level programming languages. Programmers wrote a compiler - a program that takes code in a specific language (such as Fortran or C) and translates it into Assembly code which would later be run through the Assembler, or even directly to machine code. Writing a compiler was complicated at first, but once you have a program that compiles C code, then you can write a newer, better compiler in C itself - and use the previous compiler to compile it.",
"Think of it like this. You understand the sentences used to explain this, because you understand the base words. A sentence is of course simply a series of words. The sentence is a high level language. The individual words represent machine language. IE you understand the sentence because you understand the meaning of the word. There is an additional layer of letters that make up the words. You understand each letter and the word makes sense... This represents the binary heart of a computer. At this layer there is only two states, true or false. The hardware interprets these true false statements to machine level language which is then subsequently used by higher order languages. Hopefully that makes some sense... Edit words n stuff."
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9azjyq | How does a computer cooler works and why shouldn't I just leave my computer open and point a fan at it? | Sorry for the dumb question, I'm genuinely curious about that. One of my extra coolers stopped working so I've been doing this instead, afraid my computer would overheat. I've been using a software to keep track of the inside temperature of my computer and everything usually stays within the 20-40 °C range. | Technology | explainlikeimfive | {
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"This is technically ok (as long as all your temperatures are good, which you are monitoring). Just be careful about dust. With the way your computer is now, it is extra prone to building up dust, which would act as an insulator, causing overheating in the future",
"Depends on the set up and load. Electricity produces heat, and the tiny places in between electronics are hard to get air through. Thermal transfer is a more efficient way of keeping those hotspots down. If just one of your tower fans went out there is no difference. If your CPU cooler or GPU cooler went down then you could lose longevity or performance. The hotter electronics are the worse they perform.",
"So the cooler has two parts, the heat sink and the fan. The heat sink pulls heat off the CPU and the fan blows it towards the exhaust. Ideally your setup should pull air from one part of the case and out the other creating a current that cools all the parts. Using an external fan to blow into the side with the case off may keep it cool but it will also blow dirt/hair/dust into the computer and it leaves the guts of the machine more exposed to potential damage."
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9b147r | How do spammers get and circulate my cell phone number? | Technology | explainlikeimfive | {
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"There are different ways, one example is they call random phone numbers, and if one picks up it gets added to the system as a valid phone number. They can also use leaks, and dumps, lots of websites get hacked and don't encrypt your phone number. Also a lot of people put phone numbers on resumes, which they have on linkedin or internet which you can also acquire through data mining techniques. The most common way is probably the fact that most people sign up to websites which sell your data such as phone numbers without realizing it."
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9b1hw0 | Why are some electrical plugs so huge that they cover the outlets next to them? What is taking up all that space? | Technology | explainlikeimfive | {
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"The large component is the transformer. Household voltage can easily be stepped down to a few volts. However smaller the transformer, the lower the amps. If you look at all those power adapters around your house, you will see 2 numbers: volts (V) and amps (mA). The larger the amps, the bigger the brick. Of course, companies can slim down power bricks using more efficient transformers and other components but that requires cost. And of course, that cost is included in the equipment you’re buying.",
"Circuitry and electrical components that turn the electricity at the wall into electricity the device itself can use. In the US it's approximately 120V AC current. My phone uses 5V DC to charge the battery. If I were to funnel 120V AC current into my phone without converting it I would damage my phone. An electrical engineer would be able to explain it better but I can clear up some practical reasons for having large plugs at the wall. Portability is some of it and the rest comes from ease of use and ease of mass production. Going back to my phone, it is a detachable device that uses a proprietary or universal cable depending on use case so it needs all of the electrical equipment at the plug since it can't count on the cord I use to have the proper parts in-line. My laptop uses a special plug so it doesn't have to rely on cords that I provide, and they make it all one (mostly) continuous device. The big brick in the middle handles the conversion, in my case 120V AC to 19V DC, so it leaves the plug nice and compact. Expanding on that, a tower computer, a TV, or Blu-ray player have that part in the actual device most times so it can get away with \"universal\" power cords that only need to ferry the 120V AC to the unit and nothing else. The big ones are frustrating at the outlet but it's probably also the sturdiest way to guarantee that it doesn't break. Big, sturdy block at the part of the cord that gets moved least. Stealth Edit: Spelling, grammar, clarity.",
"Many devices integrate a converter from mains-voltage Alternating current to a much lower direct current voltage in the wall plug as opposed to a block in the middle of the cable or into the decice itself."
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9b1j9k | There were several search engines in use before Google came around (AskJeeves, etc). What made Google the ultimate game changer? | Technology | explainlikeimfive | {
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"Google was a search engine unlike any other that had come before. Way back in the day, search engines like Yahoo were actually more like the yellow page listings. They had a series of categories and categories within categories. You picked what categories you wanted then got a list of websites. For example, you might select \"News\" then \"Canadian News\" than \"Politics\" and finally go to the website for CBC politics news. Eventually, that lead to you being able to do a more traditional search. How the search engines connected the keywords to the actual websites was key. The website needed to actually contain the search terms in question. So if I searched for \"Canadian politics\" the CBC website would need to contain those words. So the search engines would actually look at the websites and pull all the words off of them. This leads to websites using tags or attempting to game the system by adding extra words at the bottom of articles in order to qualify under searches for those words. You can still sometimes see this on some websites. Enter Google. Google wanted to do something new. Googles \"big idea\" was based out of academia. In academic writing articles often reference other articles. You can, to a degree, tell the quality of an article by looking at how often it's referenced by other articles. Google decided to do the same thing with websites. So Google took what other search engines were going, reading the websites for keywords and built-in something extra. They built a database showing all of the links between pages. So if I own a website and I link to CBC News I might use the text \"Canadian news\" for that link. Google took those links, the link text (the words that appeared in blue on the website) as well as information about the content of the linking site to improve search results. So now, it was not just looking at the content of the site itself but also at what other people were doing with the site. So while there might be LOTS of sites about Canadian News, none are as frequently linked to as CBC and therefore CBC would be the top Google hit. This meant that much more frequently Google would find a good result within the first few hits wheres other search engines were more of a crapshoot. EDIT TO ADD: 2 Other things that Google did that no one else was really doing. Google maintained a database of both previous search terms and also what links in those searches got clicked. So Google used it's own data to improve the order of results. So if 9 out of every 10 people who search \"Canadian news\" actually ended up clicking on the CBC news website, then that website would be first in the results. In addition, Google automated the process of searching websites for links and search terms. While some other search engines were doing a bit of that, they were also relying on the human entered categories system. Since Google did not have that legacy system they only used the automated one, and their automation was really good.",
"Ir is likely Google won the search engine wars because it had a minimalist interface with high quality search results. It helps that all the advertising was hidden within the bias of the search results, at least at first, giving the product a cleaner appearance.",
"Google was one of the first (if not *the* first) to utilize intelligent algorithms to cache and crawl websites. Pretty sure Yahoo and others were still using humans to physically find web pages and hand enter then into the searchable database. Since Google was able to automate it so effectively (and continuously improving their algorithm to show the most relevant results) they kind of buried everything else for like, 20 years.",
"For another perspective, before Google, Yahoo was *the* top search engine, and they billed themselves as a media company. They didn't offer search, but advertising. Search was boring and just a way of attracting end users to their site, they didn't take it seriously. Google did take it seriously, and had a hunch that by offering the best in service that was really in demand, they could take over the market. They independently discovered the Page Rank algorithm, as they called it (it was previously described in a scientific paper having something to do with biological taxonomy, or some shit, no one saw the parallel until years after the fact), and it provided better matches than anyone else. End users don't give a fuck about advertising, no one likes advertising, so they're going to flock to the best solution. There's no brand loyalty here... Yahoo lost their user base because they weren't appealing to their users, but their customers, the advertisers who actually gave them money. Their mistake. Instead of trying to negotiate advertising deals, they should have captured the market, and let the advertisers come to them and beg for ad space. Then they could have charged what they wanted. This is what Google did - it's simply a more effective business strategy that everyone has since tried to copy."
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9b1l40 | If gaming consoles are basically computers, why do game developers have to develop games for PC *and* consoles? And why can't a PS4 run PS3 and PS2 games? | Technology | explainlikeimfive | {
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"Video game consumers consoles are computers however they are not PCs. They have a very niche set or hardware and are designed in a way do that game developers can get a lot of performance out of relatively modest hardware because they know EXACTLY what they are working with. Conversely, PC game manufactures need to develop their games with the highest performance in mind, but also need to perform on the mid range cards. The reason that consoles are not always backwards compatible is because the architectures and hardware changes from generation to generation. When this happens, they can no longer directly support the older generation and must often be accomplished via emulation. There is a MASSIVE overhead in performance requirements for emulation and the console simply doesn't have the chops",
"Because the system software and hardware is wildly different. The current gen is the most PC like gen so far, with the Switch being closer to phones and tablets. Previously, they used very different processors which games had to take advantage of - because of this, games were much harder to develop for since there could be massive changes between platforms (especially with the PS3, which used a very new CELL processor. It was notoriously hard to develop for) Now that current consoles are so PC like, it's easier but there's still some key differences like the system software and optimisations for the specific hardware."
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9b1pua | Why do old songs have a crackling sound? | & #x200B; | Technology | explainlikeimfive | {
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"When songs were recorded on vinyl records occasionally damage to the physical medium would introduce crackling noises when played by a record player. The older the record, the more damage it incurred, unless carefully protected by the owner."
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9b9mql | What prevents the creators of an encryption method to decrypt any encrypted data? | Technology | explainlikeimfive | {
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"The methods used for most if not all commonly accepted encryption algorithms are publicly known. The good ones are designed in such a way that knowing the method used is irrelevant if you don't know the encryption key or password either set by the user or automatically generated for assymetric encryption. Like you've hit on yourself, *someone* will always know the method, and it's assumed that that someone can either be bribed or tortured to reveal the details. Since cryptographers aren't big on torture, they generally avoid the problem by just making sure everyone knows how their algorithms work."
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9ba4mk | how do cellphone carriers limit video streaming to a certain quality for example 480p | Technology | explainlikeimfive | {
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"They don't, your app/browser/plug-in is monitoring your bandwidth and scaling down when necessary. For those with an option to lock in a high resolution, you will have to wait through the lag while it buffers.",
"It's actually more to do with the player playing the file. Video files are presented to a player in a wrapper called a manifest, this manifest can contain lots of info, including links to versions of the video for different bandwidths. Lower bandwidths mean lower resolution. So when your video starts it does some.adjustments and assessment on available bandwidth and seamlessly switches to the best available video. You often see this happening when starting a stream and its low quality but a few seconds in it clears up to a lovely HD stream. What your carrier might be doing is rate limiting data from certain websites to prevent your player from ever being able to play the hd options in the manifest. So they aren't interfering with the video quality directly, just not allowing high speed data transfer from YouTube"
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9balln | How can solar panels turn light rays into electricity ? | Technology | explainlikeimfive | {
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"The material in the solar panels has a somewhat tenuous relationship with its own electrons. When \"mr right\" (frequency) photon comes along it can bump those electrons right out of their current state, allowing them to go off and indulge that nomadic lifestyle they often dreamed about. En masse this causes the electrons in the material to shift, and conductors attached to the material can catch the rebellious electrons and add them to their masses - resulting in a flow of current if there's also a source of replacement electrons, as one could expect in a closed circuit."
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9bbcpa | How do highway police speed traps work? | Technology | explainlikeimfive | {
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"The radar guns that they use are decent at picking up discrete signals, so it'll be able to give to separate readings when two cars pass by. They also typically won't chase down every little violation, and if the trap is well-hidden they won't have to; instead, they'll just pick up on those individuals that are going 5-10 mph faster than the surrounding traffic."
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9bdhd2 | How does defogging the windshield work? | I feel dumb for this, but I never know what temperature to put the air to. Also why doesn’t it help when I turn the AC off but still have the fan blowing air from outside at the window? Shouldn’t that equalize it?? Edit: RIP my inbox. Thank you for so many answers. Please do not share more Mark Rober links there are like 5 in the comments already! If you want more of an in-depth answer there are several recommendations down there to look him up so do it! | Technology | explainlikeimfive | {
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"Think of air as a sponge. However the temperature of the air determines the size of that sponge and how much liquid it can hold. The colder it is, the less water the sponge can hold. The air always has some amount of water in it, this is air humidity. When the air touches the cold windshield, the \"sponge\" shrinks and suddenly can't hold all the water it was holding. This extra water is dropped off and left on the windshield. This is fog. In order to defog the windshield you need to remove the moisture. The best way to do this is to use a big dry sponge, (warm, dry air). Generally the humidity inside the car is higher than outside so ideally, you want to use warm air that is coming from outside with the AC on. Part of what the Air Conditioning does is reducing the humidity. So when you turn the AC off and just blow outside at the windshield, this will eventually work, but is left efficient. An important note, AC doesn't always refer to cold air. The AC can be on while hot air is coming out too.",
"Moisture fogging the inside of a windshield is caused by warm air filled with water vapor hitting the colder glass of the windshield. This is much like liquid collecting on the glass of a iced drink on a hot and humid day. The warm water vapor comes from you and the other living beings inside the car. Thus, the defogging has to address both causes: the difference in temperature and the moisture. Air from outside is less humid than inside and can cools the air to the windshield temperature. AC with warm air heats up the glass to reduce the temperature difference and AC dries out the air. The choice comes down to if you want it hotter or colder in the cabin.",
"Air holds more water when warm. When cooled, it will drop the water. So if the air in your car is warm and has enough moisture in it, when it touches your cold windshield it will drop the water and fog up your window. To stop this, you can - 1. Turn on your defroster and set it as hot as possible. It will blow hot air on any moisture there, evaporating it, and it will heat up your windshield so it won't be colder than the air in your car any more. 2. Turn on your defroster and set it to middle temperature (i.e. the same as outside). Eventually the air in your car will be the same temperature as the outside air and it won't condense when it hits your windshield. Note that you'd get the same effect faster if you just rolled down your windows while driving. 3. Turn on your defroster and set it to as cold as possible. It will probably fog up really badly at first, but then it will clear up, especially as your run the wipers. Your AC acts to remove moisture from the air in your car. Then, with the windshield *colder* than the outside, the outside air will condense water on the outside of your windshield where your wipers can conveniently wipe it away. All three work, but the first is by far the fastest (and convenient on cold days when you want heat in the car anyway). The third works fine if you don't want hot air blasting in your car (such as on a hot, muggy day) and can live with your wipers on to continuously clear the fog forming on the outside. The second is really really slow unless you just roll down your windows, and then you have to live with whatever the climate is outside.",
"It depends on exactly what kind of problem you’re experiencing. The key concept you need to internalize is that **fog/frost occurs whenever humid air meets a relatively cool surface.** This is true whether it’s your car or your house or a glass of soda pop. If there is fog on the *inside* of your windshield, that means that the air *inside* your car is humid and the windshield is relatively cool. You can either fix the former problem by running the A/C (which is—first and foremost—a dehumidifier), or fix the latter problem by heating up the windshield (by blowing warm air on it). For maximum effect, turn on the A/C, blast the heat, and set the airflow to blow at the windshield. In most cars this is possible, even though it may seem like a contradiction. You also might want to try buying auto glass cleaning wipes that are specifically designed for the inside of the windshield. If there is fog on the *outside* of your windshield, that means that the air *outside* your car is humid and the windshield is relatively cool. You can’t control the air outside your car, so just focus on heating up the windshield. Most likely, all you need to do is ease up on the cooling. Maybe open a window. If you live in the south and the heat is unbearable, point the airflow at your feet for a while. Running the wipers may help—if it doesn’t, buy new wipers and use a better cleaning solution. If there is *frost* in the outside of your windshield, it means the air outside your car is humid and the windshield is relatively cool. Same problem, really, just a different season. Heat the windshield. And bust out the scraper. If there is frost on the *inside* of your windshield, buy a new car. Or move. Edit: notice that all of these solutions involve heating the windshield. A warm windshield is a dry windshield. That’s why the rear windshield has those lines on it—they are just little electric heating strips. Land Rovers used to have them on the front windshield too!",
"Follow up question; is hot or cold air more useful in this situation?",
"The fog on the windows is primarily caused by differences in moisture rather than differences in temperature, though temperature plays a role too. Air that travels through your car's AC is also dehumidified, so if it blows on a humid windshield it will take some of that moisture away from the glass, which is what defogs the windshield.",
"For best window defogging you need hot, dry air. The best way to get this; 1. Temp selector to full hot 2. Fan on full speed 3. A/C on (helps dry the air...you'll still get hot air since the heater easily overcomes the A/C cooling effect) Most cars automatically engage the air conditioning if you select window defogging mode. Most cars don't even tell you, meaning the A/C light stays off.",
"If you were 5: the AC takes water out of the air so that it can absorb the water that's on the window faster. How it works: Hot air can hold more moisture than cold air. The AC cools the air and water condenses out of the air, the air is then heated back up and it is ready to absorb more water because it now has less water than it started with. This is how dehumidifiers work as well.",
"Fog on the inside of windows is due to condensation of humidity in the car onto cool/cold glass. It is nearly always more humid inside a car than outside of it: you sweat constantly(even if it is in minute quantities), your breathing releases moisture, wet clothes and shoes from the rain or snow, all of it in an enclosed space that isn’t ventilated when nobody’s in it. Using air from the outside of the car helps(no recirculation) because outside air is usually drier. Blowing warm air on it helps because it makes the water turn back into vapor. Using the AC helps even more as (I won’t get into why that is) usually as you cool air you dry it at the same time. So for max effect, the outside air is cooled to dry by the AC, heated back up by the heater core and blasted on the windows by the fan. In northern climates like Canada, if you know it’s not supposed to snow in the foreseeable future, you can leave a sliver of window open to let that moisture escape in the cold dry air outside instead of condensing in the windows."
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9bgpdp | How are replay scenes in sports video games made? | Technology | explainlikeimfive | {
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"There's multiple ways of going about this. Most just save the game state each physics step, or just save the differences between the previous and next physics step (delta). This would effectively be almost like a video recording. Some games (like Starcraft) instead save the starting game state, and then unit *actions*, and then play the game with prerecorded controls."
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9bjvhp | Why is the US medical industry still heavily reliant on fax machines despite Obamacare initiatives to digitize records? | Technology | explainlikeimfive | {
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"I have been told by doctor offices that the fax is secure, but email is not. The medical world is very concerned with patient privacy, almost to a fault, and it seems only a fax cannot be intercepted.",
"There are well established, decades-old procedures to treat faxes as legal documents. Those same procedures exist for digital records now, but they are less well known and less established. If you use a fax, you *know* you are doing it right and won't break regulations or expose yourself to liability. This is only *probably* true with a digital record. Also, as someone who works a lot in medical IT, I can tell you hospitals are *terrible* at it. They are super conservative, mostly concerned with complying with regulations, and doctors are empowered to the point they just refuse the change. Many of them are still running computers from the 80's and 90's weren't designed with the internet in mind. Each one is a messly little snowflake, jury-rigged over decades to barely function like something form 2003. Getting rid of faxes is often the least of their worries. Finally, unlike what other people tell you, it has **nothing** to do with security. The fax format is completely unencrypted, it is a trivial matter to fake a fax. And most phone lines are digital at some point these days."
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9bk48f | How do computers display graphics? | Technology | explainlikeimfive | {
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"Imagine 9 people sitting in a 3x3 square. They each have a black or white sign that they can hold up depending on what I tell them to do. I would be the graphics card in this example and they would be individual pixels. In a grid like this 1-2-3 4-5-6 7-8-9 So I tell certain people to hold up black and and certain one to hold up white and we can create a very basic picture this way. Is I told 1, 3, 5, 7 and 9 to hold up black and 2,4,6,8 to hold up white, they would form what looks like an X. Then a minute passes by and I tell 1,2,3,5 and 8 to hold up black and 4,6,7,and 9 to hold up white and we have now made a letter T. A graphics card does the same thing, but it tells a lot more \"people\" what to do. It doesn't just tell them to hold up black or white, it can choose from a massive selection of colors to create images. And it does this X number of times per second. Any questions?"
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9bm0ig | How does a treadmill calculates the amount of calories burnt when we run on it? | Technology | explainlikeimfive | {
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"It does some basic math based on the distance you ran, the speed, and your weight. Its not like it's actually measuring anything. Numbers could be wildly off.",
"Calories are just a unit of measurement for energy. Because if that, a treadmill can calculate (roughly) how many you’ve burned by seeing how far you’ve ran. Ex, treadmill knows you went 2km in 20 mins so it calculates x many calories would be needed to move that far."
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9bnqz6 | How does a random number generator randomly generate numbers? | Technology | explainlikeimfive | {
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"So, I'm not getting into logic gates for an eli5. But the basics are to apply some math based formula to a seed. For example, a super simple one would be to ask the person for a number, then calculate the nth diget of pi, with n being the number given squared Of course, that's not really ransom., Every time I gave 1 I would get 3. To make it more random, you need a fairly complex algorithm. There are several that can be given a seed and produce an impossible to guess answer. But then how random your output is depends on how random your seed is, asking people gets both tiring and isn't very random. But it turns out there are some really random ways to go. Measuring the exact number of bytes currently in use in the ram is a decent start. Or taking the frequency that the microphone is picking up works as well. Almost anything can be a seed, as long as it produces a large enough set of numbers to make the rng seem random (checking if the camera is on or off might be random, but it's only ever gonna produce 2 inputs, so your rng will only ever produce 2 answers). The only truly random seed we use that I am aware of ATM is radioactive decay, but that's expensive, and most people don't want radioactive materials in their computer.",
"In most cases, *pseudo*random numbers are used - i.e. a sequence of numbers that aren't random, but that has been designed to have a statistical distribution that's \"as good as random\" in many aspects; for example, each output value should be equally likely; and *given the previous value* each output should still be equally likely, etc. E.g. URL_0 is a popular method. URL_1 is a simpler one, but has worse results.",
"It can't. It can come close, but it depends on what you need it for. A simple program takes an initial value and then does math that gets a sequence of numbers that approximates randomness. URL_3 If you're using it for encryption: URL_1 A more secure way is to base your seed value on a physically random process. When you generate a key in PGP (or GnuPG) it tells you to press keys, move the mouse, use the disks or network. The computer pulls these events into a pool of entropy (randomness) to help make the numbers more random. Taken to an extreme: URL_0 A long time ago BASIC programs were published in magazines and you could key them into your computer. A lot had RANDOMIZE TIMER in there: URL_2 But if you RANDOMIZE with the same number the same sequence comes out."
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"https://en.wikipedia.org/wiki/Cryptographically_secure_pseudorandom_number_generator",
"https://en.wikibooks.org/wiki/BASIC_Programming/Random_Number_Generation",
"https://en.wikipedia.org/wiki/Pseudorandom_number_generator"
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9bovbr | How does file compression work? | Technology | explainlikeimfive | {
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"Imagine that you had a picture, and you chopped it up into tiny squares much smaller than a postage stamp. Then you assigned each one a color number between 0 and 255. Then you had to write down the color numbers, in order, on a piece of paper. Well in some sections of the picture, like the sky, you will have row after row of blue. If sky blue was color #17, you could write: 17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17 Or if you were using file compression, simply write: (42 x) 17",
"Super, over-simplified answer: the compression algorithm looks for repeating patterns, and then eliminates the \"full definition\" of the repeats... replacing them with a placeholder. Think of it like this: picture all the words/info in a book. Then think of a shelf with 100 copies of that book. Compression recognizes all that info as just 100 copies of the same stuff, and summarizes it as \"book x 100\" (taking much less space).",
"Essentially, pattern finding. Most data we create is incredibly sparse: we don't use the available space to its fullest. Consider if I wanted to send you the message 0000000000. That takes 10 characters. I could also send you 10 0s, which takes only t characters. Boom, I have compressed the data to only take up half the space. Now, real world data doesn't have such obvious patterns, so compression algorithms do something much smarter, but its fundamentally the samr thing."
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9bs14o | When NASA say the Rover Opportunity will "automatically initiate recovery procedures", what does that mean? | URL_0 Im guessing it would have some tasks like start heaters, send out blips to Earth, etc? Is there any sort of listing available that shows the tasks? | Technology | explainlikeimfive | {
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"It's in sleep mode to conserve energy due to the storm. Now that the weather is clear, the battery will start charging up and it's getting out of sleep mode, meaning starting up all systems, perform internal checks to see if there's any failures and starts dancing on Mars again to the music of David Bowie.",
"The rover has different fault modes / failsafe modes. From [Nasa's site]( URL_1 ) > Low-power fault: engineers assume the rover went into low-power fault shortly after it stopped communicating on June 10. This mode causes the rover to hibernate, assuming that it will wake up at a time when there's more sunlight to let it recharge. > Clock fault: critical to operating while in hibernation is the rover's onboard clock. If the rover doesn't know what time it is, it doesn't know when it should be attempting to communicate. The rover can use environmental clues, like an increase in sunlight, to make assumptions about the time. > Uploss fault: when the rover hasn't heard from Earth in a long time, it can go into \"uploss\" fault -- a warning that its communication equipment may not be functioning. When it experiences this, it begins to check the equipment and tries different ways to communicate with Earth. The rover has different antennas: [high gain, low gain, and UHF]( URL_3 ) -- using the lowest power, most directional antenna is important when power is critically low due to lack of sunlight. The clock is important for communications - both to determine where in the sky earth would be for pointing a directional antenna, and understanding when a [Mars Orbiter]( URL_2 ) might be overhead. Spirit has communicated with both [Odyssey and the Mars Reconnaissance Orbiter (MRO)]( URL_0 )",
"Recovery procedures means that it will attempt to re-establish communications with Earth -- sending a \"hello\" signal at well-defined times, when Earth will be listening.",
"Since you cant really send technicians out there to fix it. These things are designed to fail in many different ways, but still recover as much functionality as possible. Most situations have already been planned for, and the code running on the machine has several redundancy measures to ensure it doesn't need physical intervention to keep it working.",
"Ever boot up your computer? How does your computer know it's a computer and not a toaster? It has a set of instructions that it runs when it first turns on. Thoes instructions, that the recovery. The Rover has the same thing.",
"Basically once it has enough power it'll boot up. And then, like your laptop, it'll load it's operating system, and search for signal. In this case it'll be earth instead of WiFi though"
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"https://en.wikipedia.org/wiki/List_of_missions_to_Mars",
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9bsfuc | Why do OS’s need to restart after an update? | Technology | explainlikeimfive | {
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"text": [
"Because it massively reduces the potential for the update going wrong. The update is actually not installed until the restart. Then, the OS can go through a well-defined process where it it knows exactly what happens in what order and there are no programs or OS components running that could interfere with the update. In theory, it is possible to build an OS that can update all its components while it's running, but it is much harder to get right, especially given how large and complex a modern OS is.",
"When your computer starts up, it loads the OS from the disk and runs it in memory. An update will change what is on the disk, but until you restart, the old version is still running memory. If there is a bug or security vulnerability, you want to make sure you are running the new version ASAP.",
"I would argue that the main reason is that it simplifies the life of the programmer implementing the feature that is being updated. When your computer turns on, it goes through a well defined set of procedures to initialize settings and software stored on the disk. Every feature that is implemented on your computer needs to support the case of being in the state of not being started (or running) and then become running, based on data stored on the disk, because your computer will be stopped and started by the user. When you create an update that changes those programs, but those programs are *already running* and these programs while they have the same name may organize their data differently. If you wanted to avoid a reboot you'd have to write code not only to support starting the program fresh, but also for silently transforming all the existing data in memory. This is even harder because updates are not necessarily always installed, so if you are installing version 12 of something, you might be installing that over any version of 1-12. For example imagine updating the software that controls your WiFi card, if you want a seamless update you'd have to completely replace the software running it, while not disrupting any existing connections or losing association with the AP. That may not be possible depending on the update, and if it's not, then every other program depending on the WiFi card breaks in an unexpected way to those programs. All of this is a giant hassle, with a very low return on investment, so it's just easier to make the user reboot their computer which can take less than a minute. It is better defined transition for programs than dependencies they depend on magically changing mid-run. Historically old versions of Windows, such as Windows NT made you reboot not only after updates but even to change simple settings on your computer, again for the same reason, but as new versions (such as Windows 2000) were released they got better at allowing you to make these changes. Additionally there have been feature implementations in Linux (a different OS), that allow very low level hot-fixes to be applied without a reboot. But again a lot of engineering work goes into making these features, that really just avoid a 1 minute delay that the user might not care about (if it reboots over night)."
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9bt7ry | Why are complicated passwords better than long passwords? | Technology | explainlikeimfive | {
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"text": [
"They aren't. A password 10-20 characters long with special characters and capitalization takes less time to \"hack\" than a simple 50 character long phrase. & #x200B; Edit: to add a bit more, the reason for this being is a computer \"guessing\" your password all day long will be not only be guessing common passwords and variations of, such as \"!QAZ2wsx#EDC4rfv\" (which is just a pattern on my keyboard), but the amount of guesses a computer would have to make to guess something 50 characters long is exponentially higher than 10-20."
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9bw3uo | Why are more toilet flushes not like the water-conserving ones that they have on airlines? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Its expensive to replace a system that works, and most of the water if not all is cleaned and goes back into the water cycle as vapour.",
"toilets on aircraft, trains, and rv’s, flush waste directly into a holding tank which then must be pumped out and then discharged into a sanitary waste system eventually ending up in a treatment plant. Residential and commercial toilets don’t have holding tanks, waste must be carried by water, thru underground sewers to be treated. Great improvements have been made to use less water, but the solids still have to be ‘floated along’ by use of other waste water."
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9byukd | what do they do to cars when you get an oil change? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Lift your car up, unscrew the oil drain bolt from the bottom of the motor, let your old oil drain into an oil pan, put a little bit of new oil in and let that drain to get any residual old oil out, put the drain bolt back on, fill your engine with new oil."
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9bzyrk | Why super High Definition Televisions just make everything look like a soap opera. | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"I think you're taking about the motion smoothing feature. I turn that off in the menu first thing. It just feels weird. TV is supposed to be 60 frames per second and movies are supposed to be 24.",
"This is a large controversy among people who are aware of it. Apparently, there's some segment of the population who cannot notice the difference. I refer to these people as \"insane people\". However, it is a result of a feature that goes by different names, depending on the manufacturer, but what it does is interpolate the frames in between the frames that are present in the content, to smooth it out to a much higher frame rate, either 60 frames or 120 frames per second. The problem is, they turn this feature on by default. And this feature sucks ass. The only type of content I can imagine where this would actually be appreciated might be with sports. It absolutely ruins movies and television that are either shot on film, or intended to look like they were shot on film, because the higher frame rate robs the sense of drama that is inherent in the 24 frames per second medium, which is what film was typically shot in."
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9c0db7 | How does a mobile phone call reach the other party? What happens after the signal reaches the cell phone tower? | Technology | explainlikeimfive | {
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"text": [
"So, for mobile phones, any time they are on, they \"register\" with the network by connecting to a tower and authenticating, and they periodically keep in communication, even if they're not sending/receiving calls or data. When this happens, obviously the local controller for the tower (which usually controls multiple sites) knows where you are, it tells a regional database, which keeps a national database updated. When a call comes in, this goes in reverse--you make a call. The call query hits the national database, which routes to the right regional area, then the regional area directs the call setup to the right controller, who then pings the handset to receive the call."
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9c56mc | What are the advantages and disadvantages of software forking, and the legalities of it with regard to licenses and other issues? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"In code management of software projects \"forking\" is used primarily for _divergent_ development paths with the same original codebase, whereas \"branching\" is used for _convergent_ development. The difference here is that at the time the decision is made to \"fork\" one believes they will never bring their work back to the \"other fork\" (the path left behind) and that both tongs of the fork will continue with their own lives, typically their own management and own roadmap. With convergent management you start developing down two paths, but your intention is to bring them back together. This would be for scenarios like a team that needs to continue to manage and bug fix a current release of software and a team that needs to start working on a next major release. You'd eventually merge back in all relevant bug fixes from the \"maintenance branch\" before you finalized the \"new version branch\". So...the disadvantages are typically tied to _the system_ that you're using to manage software as they do these things differently. for example, if I were to fork something in MOST source control system I could then have total independent ownership over source control, but a branch would still be \"owned\" (controlled) by whomever set it up originally. So...one advantage of \"forking\" would apply if you wanted to create a truly new version of software under different management. A disadvantage in most systems would be that it'd be more difficult to merge back changes to the original and keep track of versioning. This is because \"forks\" _typically_ are like starting an entire new source control universe for a project. The license issues are really not related here. I assume you're asking this about open source software branching/forking. Regardless of the _mechanism_ used, the licensing issues are usually the same. E.G. you can't change and distribute software using a fork that you wouldn't be allowed to using a branch. At best, if you were to create a fork it makes it _more clear_ that any future work is being done independent of the original project and you'd have a clear \"their software vs. my software\" line in the sand (where working on the original projects source tree would make it appear clearly that you were working within the context of their project). This ignores the practicality which is it's unlikely that you'd be able to effectuate a branch or fork other than a local-development version unless you were an administrator of source control for the original project!"
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9c69k9 | - How does remastering work? If the source material produces a blurry film 25 years ago, how do they make it clear now? | Technology | explainlikeimfive | {
"a_id": [
"e58b3i7"
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"text": [
"So film is actually very high resolution. Like, the actual material that movie cameras record on. If they can go back to those original high quality sources and then use modern technology to process them, they can get better results because modern tech can preserve more of the resolution that was still on that original film."
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9c8njt | Why do people host torrents, and what benefits do they get. | Technology | explainlikeimfive | {
"a_id": [
"e58vmra"
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"text": [
"Many people host torrents because they feel like they should give back when they get something. It's an honor system and torrents just don't work if no one seeds them. There have been (and maybe still are, I haven't paid attention to it in a while) trackers which require users to contribute a certain amount in order to leech files. You have to maintain a certain ratio of upload:download to be a member."
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9c9m45 | How does your phone automatically know which police station to call when dialing 911? | How do cellphones and telephones (past and present) direct emergency phone calls to the nearest police station? | Technology | explainlikeimfive | {
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"text": [
"Your phone doesn't know that at all. It just notifies the phone company that an emergency call is needed. The phone company knows the approximate location of every phone, and automatically chooses the assigned emergency call center for that location.",
"Cell phones are always connected to cell towers, which know which station is closest, it doesn't change. in the past, with landlines, they were just linked to specific 911 centers via physical location, which also didn't change.",
"Your cell phone sends a signal to a large tower. This tower then sends the signal to other towers until it reaches a large hub then sent out again. They see which tower your phone sent the signal from and use that to determine your location",
"This is routed using a FCC mandated service called Enhanced 911 ([E911]( URL_0 )). When you dial 911 on your phone, the call is routed to the local public safety answering point (PSAP) center using the location information sent by your device. Wireless devices are slightly different as the local switch needs to also send over your location information (lat and long with a 300 meter tolerance) within 6 minutes of when the request was made. There are certain protocols and requirements for keeping E911 service trunks up and passing traffic to where a carrier could be penalized millions of dollars if they allow their E911 services to fail, not contact the FCC within a time limit, and not repair the trunks within a time limit."
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9cb7le | What does a CPU basically do? | I tried searching it up online but they use too complicated words or maybe I'm just dumb to understand what they mean. | Technology | explainlikeimfive | {
"a_id": [
"e59el90"
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"text": [
"A CPU is basically a calculator with a bit of memory. It adds numbers, multiplies numbers, etc then stores the result. Unlike a calculator, it reads in a series of instructions from memory rather than the user having to physically press buttons to tell it what to do. Also unlike a calculator it can make \"decisions\". It can compare numbers and execute one set of instructions if the comparison is true, and another if it's false. Equivalent to something like \"If a = b then do this, else do that\". That's essentially all a CPU does. It doesn't sound like much but because they can do billions of those per second you can make them do very complicated things with just those instructions."
],
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9cd9ck | Ya know those ‘in utero’ pictures? Not ultrasounds or 3D, but the actual pictures of babies floating around that they put in baby books. How do they get those? | Technology | explainlikeimfive | {
"a_id": [
"e59thnb",
"e59tywk"
],
"text": [
"Rather than taking one ultrasound, they took lots of ultrasounds and used a computer to turn that into a 3D model of what it looked like inside the womb. [National Geographic did this with a dolphin, a dog, and an elephant back in 2006]( URL_0 )",
"In the past, before CGI US imaging, they would put a tiny light on a stick to backlight, and use an endoscope to take the picture."
],
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"text_urls": [
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9ce9fl | How does cell shading work? | Technology | explainlikeimfive | {
"a_id": [
"e5agger"
],
"text": [
"Cell shading uses fewer steps (gradations) from bright to dark - giving white highlights and black shadows a sharp and clearly defined outline. (Think 3 shades instead of 3,000.) When a computer renders a 3D scene, it simply decides on a limit in order to decide where to draw the line (between shadow, base color, and highlight.) So if you have 3,000 shades in a normal image, the computer could decide anything over 2,900 is white and anything below 500 is black."
],
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9cfdj2 | Why Windows still slows down after some time, and it's not fixed even when reinstalled. | Technology | explainlikeimfive | {
"a_id": [
"e5ab48n"
],
"text": [
"Reinstalling WILL fix a Windows installation that has slowed down after some time. If it doesn't, then you're not reinstalling properly. Note that in this case, reinstalling means that you back up your data, wipe the PC's hard disk, reinstall Windows, reinstall all your programs, and restore your data. That WILL speed things up again. Nothing else will. However, you can speed up Windows a lot by uninstalling any programs you don't use. Also, disable disk indexing if you don't use the search feature. And don't use a modern internet security suite unless your PC is up to the job - try with the basic Windows Defender instead. Also check that auto-defragmentation if your drive is running every week or so. & #x200B; & #x200B;"
],
"score": [
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9cfngo | ms dos games | Technology | explainlikeimfive | {
"a_id": [
"e5acfes"
],
"text": [
"Graphics and textures are done the same in every game, regardless of what it is going through. The game accesses the video driver (really the video register in the older games) and basically takes over drawing the screen. Like that it can produce graphics beyond what basic operating systems like DOS can produce simply because it no longer has the limitations the OS has implemented to make things easier. Any software that is full screen works in a similar fashion. Later games took advantage of systems like GLiDE, OpenGL, DirectX and others to simplify talking directly to the video driver. By using a limited but standardized instruction set, you can program for a larger amount of hardware at a higher quality than if you went directly for the video register. Mind you, I might be wrong in a couple spots, but I believe that is the general gist."
],
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9cfqkj | How do blogs, clickbait, and"fake news" sites actually make money from ads? | Technology | explainlikeimfive | {
"a_id": [
"e5acp73"
],
"text": [
"There are three kinds of ad revenue. The first is as you suggest. It's called affiliate marketing, and they get paid when you click a link and buy something. That's actually fairly lucrative, as people who do end up clicking almost always buy something. The second is pay per click, where the site gets paid only when you click the link, but you aren't required to buy anything there. That's better for the site, as it can be used to advertise other blogs, TV shows and other \"free\" things. The third is pay per impression, where the site gets paid for every unique view to the ad. This is best for the site compared to the advertiser, and is best used for things like Coca-Cola or something that is interested in keeping their name public. Because each type of ad is easier for the site to use, they tend to pay less per item."
],
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9cgpey | How is Google Maps doing all this crazy 3D stuff? | Technology | explainlikeimfive | {
"a_id": [
"e5ak3wy"
],
"text": [
"Most likely a combo between flyover mapping, satellite imagery and manual vector art done by designers"
],
"score": [
3
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9cgq51 | How do transition lenses on glasses work? | Technology | explainlikeimfive | {
"a_id": [
"e5attry"
],
"text": [
"According to [Transition's website]( URL_0 ), the lenses contain photochromic molecules, which react to UV light and darken the lenses. The sun gives off UV light. Although some UV light (or UV radiation) is blocked by the ozone layer, UV-A and some UV-B radiation passes through. This UV-A and UV-B radiation causes the reaction in the lenses. You can actually see this happening if you have a UV flashlight - just shine the flashlight on the lenses and it instantly turns dark. Be aware if you do this that it takes a while for the lenses to turn back normal!"
],
"score": [
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"text_urls": [
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|
9ckbxs | How to stop getting ads of things you ve talked about but havent actually search for it? | Technology | explainlikeimfive | {
"a_id": [
"e5ba95c"
],
"text": [
"Boy oh boy do I have a podcast for you! [ URL_0 ]( URL_0 ) & #x200B; This basically explains what is going on in terms of Facebook ads, but the same principles apply everywhere. It's a really complicated question to answer here and that podcast is about 30 mins and will do a really good job. In short, your phone isn't actually listening to you at all, it's just really really good at drawing associations from other behavior. Anyway, I hope this helps and you enjoy!"
],
"score": [
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],
"text_urls": [
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"https://www.gimletmedia.com/reply-all/109-facebook-spying"
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9clpz1 | How can people have heart transplants without dying during the procedure? | Technology | explainlikeimfive | {
"a_id": [
"e5bivhr"
],
"text": [
"A [cardiopulmonary bypass]( URL_0 ) is performed, connecting the patient to a machine that pumps and aerates blood in a sufficiently similar way to how the heart and lungs does it to keep their body mostly functional for the time the surgery takes. If one isn't available, and waiting isn't an option for whatever reason, the human body can be resurrected after extended periods of cardiac arrest with little or no brain damage if cooled down beforehand (though brain damage does happen often enough that this is not done)."
],
"score": [
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"text_urls": [
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9cmn77 | What is "geo-redundancy" when it comes to cloud back up? | A specific cloud service was recommended to me with the caveat "if you don't mind geo-redundancy." Can anyone explain geo-redundancy in the context of back-up cloud storage. Cryptomator was the product being recommended. And no, I don't want to *just* use iCloud/OneDrive/Google Drive. | Technology | explainlikeimfive | {
"a_id": [
"e5bpxoy",
"e5bpusn"
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"text": [
"Normal redundancy would be two or more computers that are capable of performing the task. Redundancy protects you against hardware failures in the computer that would take them offline Geo-redundancy is computers in two or more far apart locations that are capable of performing the task. Geo-redundancy protects you against natural disasters which might take an entire data center offline. It doesn't matter if a hurricane floods the data center in Florida because there are identical ones in Idaho and California which aren't going to be taken out by the same event so its unlikely your system will go down Not all cloud providers offer geo-redundancy, if they only have one main data center then a single disaster can take out all of their equipment and knock your systems offline",
"Your information will be spread across datacenters throughout the world. It *shouldn't* be a problem, but some people have personal or business reasons that cause them to not want their files stored in a different country."
],
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9cpd3m | How do USB wall adapters convert large voltages in such a small cube? | Technology | explainlikeimfive | {
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"This becomes a far more interesting problem when factoring in the fact that the wall output is AC and we need DC for USB. Alternating current is what is found in our wall outlets, the electricity goes back and forth really fast in a pattern like a sine wave. Direct current, the electricity just goes in one direction all the time. We need direct current to charge out phones and what not. Anyways, here is how it is done. The problem: we need to take the voltage down from 120 volts (in reality this is a bit less because of the capacitor smoothing mentioned before but still way more than 5) all the way down to 5. Transformers are devices which do this, however they require AC current and the slower the switching of the AC current is, the bigger the transformer needs to be and the more inefficient the transformation is (this also results in a lot of heat which brings its own problems). AC current from the wall alternates 60 times per second and this is too slow, we would need a massive brick to convert this directly, maybe a fan to cool the entire thing. We have tools which convert AC to DC, so that isn't a problem, but converting slow AC to faster AC isn't really possible without first turning it into DC. So the goal high voltage wall AC - > high voltage DC - > fast high voltage AC - > transform into low voltage AC - > low voltage DC. A rectifier is a device which makes it so that AC current is converted roughly to DC current. The problem is that it is choppy, [this image illustrates this]( URL_0 ). I won't get into the specifics of how a rectifier works, but it consists of devices called diodes which only allow electricity to move in one direction. You can look it up online for more details. But as you see, its main goal is to bring all the waves onto the positive side. We don't like choppy voltage so we use something called a capacitor, which is a device that holds charge temporarily like a battery however has a nice tendency of wanting to keep voltage constant on the wires (it charges up to higher voltage when the voltage is at the peaks in that image, reducing the voltage other devices connected to the same wires in parallel use, then when the voltage is low on those wires, it instead releases its charged up voltage, bringing the voltage back up on these wires). This isn't ideally smoothened, but its pretty good, [here is an image]( URL_1 ). Next, with the use of a transistor (this is just an electronic switch, imagine instead of you needing to physically flip a switch, there was an additional wire turning the switch on and off) and a clock circuit, we have this transistor turn on and off real fast, producing AC switching many thousands of times per second. Because the transistor is a switch, the current coming out is a rather blocky AC than a nice smooth sign wave but a transformer still works fine with this so it’s alright. This is fed into a transformer which converts it to low voltage. Finally through a second rectifier converting it to DC, finally through an another smoothing capacitor, and out into the USB port. One of the nice additional features is that the \"jitter\" of smoothening I showed in the second image above is less noticeable the higher frequency the AC is. This jitter generally is not much of a problem in most cases but IIRC batteries prefer smoother current for their longevity and computers become unstable with if the jitter is bad enough so its best to minimize it. This process has been innovated with things like computer chips regulating everything inside (mainly the transistor speed, which happens to allow for control over a lot) but the basic principle remains. This is a lot of stuff to do in a small USB charger. In fact, [we can barely cram everything needed for it into the brick]( URL_2 ). But it works and it fits.",
"They use something called a Switch Mode Power Supply. The general design is they have a bridge rectifier and some sort of filter to make ~120V-ish DC, this is then switched on and off very fast, usually 100s of kilohertz and fed into the primary side of a transformer. The secondary then has a rectifier of some sort and another filter. This is then fed back through an opto-isolator (a chip with a tiny light and sensor used to send signals without connecting the end electricity) to tell the switching device if the voltage is too high or too low. The switching device adjusts the switching duty cycle to get the right voltage. [Here is a good block diagram]( URL_0 ) The transformer and optoisolator are used to make sure you can't get shocked on the USB end, none of the wires are connected to any wires on the outlet this way. The very high switching frequency means that the transformer and filter components can all be very tiny (their size tends to be proportional to frequency, higher frequency needs smaller components). Older supplies operated on mains frequency which is why they were generally much larger and heavier."
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9crha1 | when telephone communication was in its infancy and they ran wires to connect all the telephones, how did they connect overseas calls? | Technology | explainlikeimfive | {
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"In the earliest days, transatlantic communication over the phone was done via radio tower (and later microwave towers). They could have laid a cable, but the distance was too long for the technology at the time to give the voice signal enough strength to make the distance. There were other shorter undersea telephone cables laid elsewhere in the world, but they were much shorter distances. However, by the 1950s the tech was there, and a transatlantic cable was run. It didn't carry many calls, but it was there. Eventually this improved, drastically, and now there are plenty of fiber optic cables carrying all sorts of data underneath the ocean.",
"Cables were run on the ocean floor, a major part of communication still takes place through fiber optic cables run on the ocean floors.",
"The transatlantic cable. It was the first of its kind, and a literal cable that ran from Canada to Ireland to connect the western and eastern hemispheres. Ireland and England connected, and etc. Initially telegraph cables, messages were easily transmitted. Wires were probably updated, if needed, to accommodate telephone calls before the satellites came to use"
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9cwn48 | Public-key cryptography | How does the public-private key system work? Why does it work? | Technology | explainlikeimfive | {
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"ELI5 example how public-key cryptography works: Imagine persons A and B want to transfer secret message but they can only send packages to each other in mail which is unsecure. Anyone can steal a package and take what ever contents are inside or even swap them to something else. In symmetric key cryptography they would use a locked box and they both would have a key for the lock. Problem is they can't exchange keys safely. If A buys locked box, how can he send key for it to B without possibility that someone steals the key and makes copies. In public-key cryptography person A buys a lock (and keeps the key for it in some secure place) and sends the unlocked lock to person B. Person B then puts his message inside a box and locks it with A's lock. Then he can send it safely to A without anyone having access to the message. Locks in the examples are cryptographic algorithms. Public-key algorithms are much more expensive to calculate so usually they are just used to do the key-exchange: both send a symmetric cryptography key to each other using public-key cryptography. From there on they just use the symmetric cryptography to encrypt their communication.",
"[Public-key cryptography using colors]( URL_0 ) I used this, which made a whole lot of sense. (Hopefully the link works)",
"In one word: maths The fundamental idea is this: some mathematical operations are pretty quick and easy to perform, but almost impossible to reverse. A specific example used for public key cryptography is multiplying two large prime numbers. A computer can do that in microseconds. But finding the prime factors of a large number takes so long it might as well be impossible. So you have X * Y = Z, and Z is your \"public key\" that everyone can know, while X and Y together are your \"private key\" that needs to be kept a secret. Now the trick is that you can perform some additional math where you use Z (which is public) to do some operations on another number M (which is a message) to get an encrypted message C where it is only possible to get M back from C if you know X and Y. Knowing Z only lets you *encrypt* messages, not *decrypt* them - that's why it's also called an \"asymmetric cipher\"."
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9cz0gf | How does a home central AC work? Does it use any water? | The more I google about how a central air conditioner works, the more confused I get. I read that legionella bacteria is a concern with big air conditioning units, but only ACs that use a humidifier or cooling tower. I think just any ACs that use water can harbor the bacteria. I read that it’s a concern especially in large central air units, like those used in stores or office buildings. But I can’t figure out if the central air conditioners that people use on homes (with the big box outside the house) have a humidifier or a cooling tower or even use water at all. Could someone explain how home central AC units work, whether they use water, and whether they are a risk for legionnaires disease? Thank you!! | Technology | explainlikeimfive | {
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"First, lets talk legionella. This is a water borne bacteria that can cause some serious health issues. Fortunately, as you saw, it's not a concern for small scale air conditioning. Home ACs use a refrigerant (Freon used to be it, R410 i believe is the current rage). This is a chemical that boils/condenses at very specific conditions of temperature and pressure. There are a few components to the home AC. 1. Condenser - this is the big box outside. It consists of a fan, coils, and a compressor. The refrigerant flows through the coils and enters the condenser as a gas, gets compressed, and the heat is blown away by the fan. This is why when the unit it running the air coming off the outside unit is quite warm. This also condenses the refrigerant into a liquid. 2. Evaporator- this is the unit inside. It consists of tubes and the air handler. The air handler is basically another fan that blows the warm air from inside your house across the tubes holding the refrigerant. This causes the refrigerant to evaporate and cool down the air before it is passed to your house. This also drops water out of the air and reduces the humidity. The refrigerant is now a vapor which gets passed back to the condenser. It's the same cycle your refrigerator goes through to keep your food cold. For large scale units, it's usually more efficient to use water cooling rather than a compressed refrigerant. This is where the legionella concern comes from. Instead of passing the water through a closed loop, it goes to cooling tower. There, the water falls through the air, shedding the heat, and giving off some vapor. In this wet, humid environment legionella can grow like gang busters.",
"> I read that legionella bacteria is a concern with big air conditioning units, but only ACs that use a humidifier or cooling tower. The idea here is that if the bacteria are in the water and the water is able to become an aerosol in the air then people will breath in the bacteria and become sick. > Could someone explain how home central AC units work A fluid (not water) is used to transfer heat from inside the dwelling to outside. Heat can be thought of as the concentration of thermal energy in a given area, with great flowing from areas of high concentration to areas of low. The working fluid (something like freon) is compressed which takes all the thermal energy in it and puts it into a smaller volume, meaning it has a higher temperature. The heat then flows out of the fluid until it reaches equilibrium with the surroundings. The fluid is then pumped into the dwelling and allowed to expand, reducing its temperature as the concentration is reduced. Heat then flows into it until equilibrium and the cycle repeats, pumping heat out of the home. Each of the steps where the heat is allowed to flow out or into the fluid is aided by radiators and fans blowing across them. The fluid itself isn't exposed directly to the air and it wouldn't be something the bacteria could grow in anyway, so it isn't a danger."
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9d1k3b | Why does TV (usually) come through so clean and consistently while streaming on wifi tends to cut out and buffer more often? | Half the time I watch baseball on TV, other times I stream it. The TV feed is so consistent and smooth, but sometimes the internet cuts out and I have to reload the page. I understand the general gist of why this happens, but a thorough explanation would be appreciated! | Technology | explainlikeimfive | {
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"Television and internet streaming videos are entirely different forms of transmission. TV signals are just broadcast and sent everywhere at once, no matter if you're watching it or not. Streamed videos are like any other thing you do on the internet - requests are sent from your computer to the server, who then replies with the data. If there are bottlenecks anywhere along the route between your client and the server, then packets may start to get lost, have to be resent. This is what causes the stuttering and buffering.",
"The TV data is being thrown into the sky with so much power that everyone can pick it up. Your streaming data is meant just for you, so comes trickling down the wire.",
"The source of your video that sends the stream to your devices is different. The TV networks have pretty vast and redundant networks to provide excellent coverage with minimum loss of information. Let's assume cable tv, which can easily boost and repeat signals throughout the entire neighborhood with a single local distribution box to provide high quality content error free. Your TV recieves a continuous and near perfect quality signal by cable without any interpretation, beyond the standard format and display processing. Streaming from a server is different, there's no Dedicated streaming channels or midpoint signal cleaners and boosters. Just a signal originating from a server that must pass through multiple devices to get to your house. Every device is independently controlled or operated by it's Algorithms and will not prioritize your message. Instead there's juggling as multiple paths are available and devices oscillate from busy to available for your use. Generally it's fast enough, but a busy night can tax the server or strain the major connection points between you and the server. Getting close to home, the wifi is a changed medium and both slower as well as more error prone. The stream hopefully gets recieved okay... but the overhead of getting here and piecing together information leaves mixed results. Sometimes stuttering from constant buffering... sometimes missing details or strange artifacts throughout the video. Depending on the service, you might be processing two streams for redundancy checks and quality or buffering a single stream constantly, while others just stream and you hope it's well enough."
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9d3hsz | how the rewind feature in things such as the snes classic or retroarch is possible and actually works | Technology | explainlikeimfive | {
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"SNES emulators are able to write out a \"save state\" which is basically a file that contains everything the SNES was doing at any given point in time, including a full copy of system memory, any hardware flags, and so on. This allows you to immediately restore the emulator to any of those save states, and resume playing the game as if nothing had happened. The main reason this is possible is that modern computers have a *lot* more memory and processing speed than a SNES did. A full save state may require only 2 MB of memory (depending on the emulator), but a gaming computer could easily have 4 GB of memory free to run the emulator, which is enough to keep 2048 frames in memory (roughly 34 seconds at 60fps). If you're willing to trade off some accuracy, you could save once every 4th frame to keep 2 minutes in memory, or once per second to keep around 34 minutes in memory, and easily rewind to any of those saved frames."
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9d3vtc | Why do solar panels stop working? | According to a recent BBC article, after 30 years or so solar panels are end-of-life and the scrap is no good for anything but landfill. What stops them working? What makes the scrap unusable? | Technology | explainlikeimfive | {
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"The panels on the voyager space probes worked for longer than 30 years. Higher tier panels in residential solar degrade at half percent a year and should still be at 90% of their output at year 20. Even if that curve is off a bit, that's still around 80-85% at year 30. Unless the article is looking at polycrystaline panels made 30 years ago? I must be missing some detail(s). Can you link the article?",
"A quick search on the BBC website reveals no such article, do you have a source? You might be interested to hear that [a solar panel recycling plant has opened in France]( URL_0 ), so your statement that \"the scrap is no good for anything but landfill\" seems to be false. According to the Reuters article \"The robots in Veolia’s new plant dissemble (sic) the panels to recuperate glass, silicon, plastics, copper and silver, which are crushed into granulates that can used to make new panels.\" and \"Veolia said it aims to recycle all decommissioned PV panels in France\".",
"-resistance increase due to contamination over time -temperature differences causing extension/contraction resulting in decaying micro-structures -like in batteries, over time metal ions will diffuse to their respective opposite electrode -mechanical panel issues"
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9d5nh1 | how my phone recognizes when I'm taking steps and accurately counts them | Technology | explainlikeimfive | {
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"The Accelerometer in your phone detects the slight fall and stop that occurs each time you step down. It counts each time this happens as your steps. The phone also uses location services when available to be more accurate. Finally, as you use it more, it learns a little better what it should count and what it shouldn't as steps, so usually it'll get more accurate after a few months of being in your pocket. I credit magic with the last part, but it's probably some kind of AI.",
"Your phone has, among tons of other gadgets and sensors, what’s called an accelerometer which tracks motion, tracks your acceleration, and also tracks which way the phone is pointing. This helps it do things like count the steps you take, as well as show which way you’re facing (in apps like Google Maps for example, an arrow will point in the direction you’re facing - that’s the accelerometer at work). For more info, Gizmodo has [a great article]( URL_0 ) that talks about all the sensors in your phone. Hope this helps!",
"Apple devices use genetic algorithms to learn the way you walk. The more you walk the more it's movement sensors becomes acoustomed to your average gait which it then couples with location services (if available) to give you an incredibly accurate estimation of how many steps you've taken",
"How accurate are phone step trackers compared to things like fitbits and the like?",
"Finally one I can answer. Your phone doesn't actually count the amount of steps you take, it actually counts general patern of accelerations that a step have. You can actualy trick your phone, by moving it up and down like it would if you were walking and the step counter will count that as a step.",
"Your phone has many sensors inside, that measure all kinds of data like acceleration, orientation, position, the magnetic field, air pressure, and radio waves. individually it can be hard to interpret this data as you move around and do various activities all day. Your phone runs a complex algorithm that tries to answer a bunch of questions from all this data at the same time rather than any one of the data streams individually. Most importantly it tries to figure out where you are how fast you are moving and in which direction that movement is. Another algorithm takes this answer together with the raw data and tries to guess how you are moving. Are you walking? Are you running, are you driving a car etc, Once that has been decided another algorithm updates things like step counters. Apple/Samsung etc gathers lots of example of each way of moving, so say for example a video of someone walking while holding a phone in their hand, walking with the phone in their pocket, running with the phone in an armband etc and actually counts the steps manually. They then try to program this algorithm to be able to match this calibration data. Each type of motion has a distinct pattern or signature that can be recognized very similarly to how something like voice recognition or speech to text works. Most of this algorithm runs in a dedicated chip called the motion coprocessor which is a special low energy processor that runs only these algorithms continually in the background so it doesn't miss any movement but also doesn't use too much battery power."
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9d6ee6 | What are presidential alerts on the phone designed for? | Technology | explainlikeimfive | {
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"> Is it for imminent nuclear strikes? Apocalyptic meteors rapidly approaching Earth? Yes, basically. Maximum level threats that every civilian **must** be aware of. It's there so that you know disabling disaster alerts does not disable presidential alerts."
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9d7kap | What would happen if I was to stay in the first gear of my car way past the speed it could handle ? | Technology | explainlikeimfive | {
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"The valves controlling fuel and gasses going in and out wouldn't be able to close in time and burning fuel would shoot out through them, causing them to get caked in soot (and severely reducing performance). If somehow you manage to keep pushing your engine beyond that, the internal friction would eventually overcome the structural integrity of the engine and it would undergo rapid unplanned disassembly, possibly explosively so.",
"Let’s say you put your car in first gear then press the accelerator to the floor. Your car will quickly accelerate until the engine reaches around 8,000 rpm and you encounter your first limitation - the engines rev limiter. Your engines computer won’t let the engine spin faster than a programmed limit to prevent damage to the engine and will cut fuel/spark to slow the engine back down below its limit. Now let’s disable the rev limiter and keep accelerating. Your engine can probably spin a little faster under its own power, but the next limitation you will encounter is the physical limits of the engine - the fuel system can’t keep up with the speed the engine is running at. You won’t be able to get fuel/air into the engine and exhaust gasses out fast enough and the engine won’t be able to accelerate any faster, this is roughly around 10-14k rpm. The engine will also begin to sustain damage operating at this speed, it won’t last too long before something fails and you roll to a stop. Now let’s artificially accelerate the car faster, let’s strap a rocket to the roof! The engine speed will continue to climb well beyond what it can handle and ultimately the stresses of operating at such a high speed cause it to fail. It’s hard to guess how fast it can spin but I’m going to say it will sustain enough damage beyond 12k to need repairs before it could ever work normally again but still more or less remain intact, and somewhere from 16-20k the engine will catastrophically fail in a spectacular explosion of engine parts! The explosion will likely be overshadowed though by a far more impressive sight - a car blasting down the road with a rocket strapped to its roof spewing engine parts onto the road as it screams by!",
"You'll redline (go a higher RPM than your engine intends it to go) your engine and damage it if you do that too often.",
"You would mutilate you’re transmission. Some newer cars are all electronic so they can handle that kind of abuse better. But yeah you’ll just strip gears and it would make a terrible noise. Not nice.",
"Modern cars have rev limiters to stop you, but otherwise the engine speed keeps increasing until something fails. Exactly what fails first depends on the engine design. If you're lucky, the valves simply can't close in time to generate power and you can't rev any higher. If you're unlucky, you badly damage the engine or transmission.",
"You would end up causing damage to your engine. It will stay in first gear for as high as the RPMS will go, but eventually the combustion cycle will not be able to continue because it has too little time to get the fuel into the cylinder, and the engine will cut out. That is assuming the ECU doesn't have a mechanism for preventing that.",
"“The speed it can handle” is an interesting concept. The transmission and its components are actually very strong and can stand up to a lot of stress. There isn’t really a speed it can’t handle (well, there is, of course, but it’s faster than the car can go.) The recommended shift speeds are determined by the entire drivetrain as a complex, the transmission being 1 piece of the larger whole. In 1st gear at moderate to high speeds, all of the strain is on the engine as it has to rev to very high RPMs and sustain that speed to maintain the vehicle speed. (For contrast, the peak strain on the transmission occurs at very low speeds, just getting the car moving and then during hard acceleration following each upshift.) Every engine has a mechanical limit, a redline, that it physically can’t exceed without damaging itself. This is usually higher than the red mark on the tachometer, which serves more as a cautionary warning. All in all though, the longer an engine spends at high revolutions (greater than 4-5,000) the more likely something is to fail. It could be a valve, a bearing, a piston ring, a piston rod, literally anything. But any of those failures usually lead to a catastrophic cascade of other failures... In other words the engine blows up. A car cruising at highway speed usually revs at less than 3,000 RPM, for reference. Extended time at much higher RPMs just wears out the engine components, which increases the odds of engine failure."
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9d9hlf | What do a dark room for photography do to the photos. | Technology | explainlikeimfive | {
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"Photographs taken with film camera use photographic film, special paper coated with chemicals that are sensitive to light. Their brief exposure to light focused through the lens of the camera allows them to record the image, but then they must be chemically treated to retain that image and produce prints. Those light sensitive chemicals don’t stop being sensitive to light just because the photograph was taken, so handling the film outside of the camera needs to be done in a room without light, a “dark room”."
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9d9oai | A technician is coming to our house next week to increase our internet speed. If our internet is already set up and we aren’t changing providers, why can’t the company do this instantly and remotely? | Technology | explainlikeimfive | {
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"Often they can. If they have to send a technician, it's because either (A) you need a faster modem, or (B) the physical wire coming into your house isn't good enough, or (C) the line approaching your house is shared with another building and needs to be separated.",
"It's likely you will need a new modem which can handle the higher speeds. Cant do that remotely.. however they could just send you the device and have you plug it in."
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9dbdap | why do videos generally play in 30 or 60 fps and not any number in between like 43fps | Technology | explainlikeimfive | {
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"60 Hz was the standard adopted for North American AC power delivery. This later translated into the standard frequency for television refresh for analog television. Which even later translated into the refresh rate for the LCD monitors used today. As to 30 vs. 60, both are above human visual persistence (the frequency of still image projection at which we can experience seamless motion). However, 30 requires far less information and is an integer divisor or 60 so you can simply thrown out every other frame. In contrast, a 43 Hz version of a 60 Hz source would appear to speed up and slow down as it had too many frames at certain points and too few at others."
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9dbkp1 | Movies in space | Technology | explainlikeimfive | {
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"It's real. Centrifugal force can simulate gravity for anyone on the inside of a spinning ring. If the ring is real big it doesn't have to spin particularly fast. And bigger is better, because the apparent gravity decreases towards the center of the ring. So if it's small your astronauts are going to perceive a sharp gravity gradient (heavier at their feet than at their head), and that's no bueno for keeping your lunch down.",
"This isn't Hollywood BS; it's the real effect of centrifugal force. The calculation for whether you'd be able to use it consists of: R (Radius from center of rotation) a (artificial gravity) T (rotating spacecraft period) R = a(T/2pi)^^2 or a = R(2pi/T)^^2 where T > 0 If you want to figure out how fast the spacecraft has to spin, plug in earth's gravity for a, set a radius from center for the spacecraft, and you can solve for the period, thereby calculating the speed of rotation (actual speed and gravitational force will depend on where you are on the spacecraft). [edit] If you want to see this effect for yourself, just take a bucket of water, and swing it in big circles perpendicular to the ground. If the water stays in the bucket as it passes over your head, congratulations! The water in the bucket is being held in place with a force equal to Earth's gravity. You have now created the equivalent to a space station.",
"It's definitely real, although it hasn't actually be done yet. It's a well understood physical concept and is within our technological ability to construct right now. A spinning ring can simulate gravity through centrifugal force. You can try this at home by filling a bucket full of water and swinging in a circle over your head. You'll notice that if you swing fast enough, the water does fall when the bucket is upside down. The same principle applies a rotating spacecraft. As for rotational speed, it depends on the size of the ring. A larger ring would require a slower speed for the astronauts to experience the same g force as a smaller ring. A ring with a radius of 10 meters (32.8 feet) would need to spin at 9.5 rpm to achieve 1g, which is well above the comfort threshold of the astronauts inside (6rpm is generally considered the threshold at which one could adapt to the rotation, but lower rpms is always better). On the other hand, a ring with a radius of 100 meters (328 feet) would need to spin at only 3rpm to achieve 1 g. A larger ring is also better because the experienced gravity inside the ring would only be 1g at the outer edge, fading to 0g at the center. A small ring would result in a large gravity gradient from their feet to their heads, which would be very uncomfortable. It would also subject them to large coriolis forces. & #x200B; Edit: I will add though that a lot of movies use this real concept because, as you said, it is super convenient. It removes the need for filming zero-g scenes with wires, harnesses, and extensive cgi. If you want to see a film set in space that depicts actual zero-g scenes, watch Apollo 13. They filmed a lot of the scenes in space inside a[reduced-gravity aircraft]( URL_0 ) that simulates zero-g or near zero-g in 25-30 second bursts, so in those scenes, the actors and props were actually floating."
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9dckhn | How do computers play Chess? Is it a near infinite web of decisions that each have a probability of success associated to them? | Technology | explainlikeimfive | {
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"text": [
"There are a lot of possible games, yes, but there are only a finite number. Further, there's only a finite number of legal moves that can be made at any given time. Computers will follow a set of moves and the possible counter moves, analyzing both the value of a move and the probability of a counter-move. Low value and low probability moves are discarded without further computation and after a certain depth of recursive computation, the computer will give up and cease calculating further, only considering the value of of already analyzed moves. Along the way, it will take shortcuts, such as assuming that its opponent won't make stupid or pointless moves. The assumption that it's opponent wants to win dramatically narrows the field of possibilities and speeds up computation. Basically, computers take shortcuts and give up after a time, but ultimately brute-force a solution.",
"There are two techniques: 1) Develop a function that says how much more desirable one chess position is than another. Use that function to search the most desirable sequences of moves from the current position. 2) Build a learning network, and feed in games so it can see what moves win and what moves lose. After **a lot** of games, it can make the right move from the current position. Most chess programs, like Stockfish, work like (1). Alpha Go works like (2)."
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9dcuru | What’s all this stuff about DDR4, GDDR5 stuff on graphics cards? Is there a compatibility thing with them and motherboards or something? | Technology | explainlikeimfive | {
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"DDR4 is regular RAM. You find it in consumer desktops/laptops. GDDR4 and GDDR5 are special high-performance RAM only used for graphics cards. They are soldered directly to the circuit board and cannot be replaced or upgraded. Ignore the similarity in name. They share some technical details but are basically two totally different things as far as a consumer is concerned.",
"First note, gddr4, ddr4, and gddr5 are all different standards, all incompatible with each other."
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9dfiu4 | How are LED lights so bright and use so little energy? | Technology | explainlikeimfive | {
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"Traditional light bulbs produce light through incandescence, which is when a material releases light energy when heated. They are inefficient because much more of the electrical energy that goes into the bulb is dissipated as heat than light. LEDs basically excite electrons in a semiconductor which causes them to emit photons (light) of a specific wavelength while generating comparatively little heat. Therefore it converts electricity to visible light with a higher efficiency.",
"It might be worth pointing out that LED's are not necessarily that awesome either. I'll explain what I mean. A LED light is pretty awesome if you use it as a marker or indicator. Because it can be seen from afar. It's damn good as a back light of a car, or as an indicator. Because it can be seen from afar. And the LED's last a long time before you need to replace them. But LED is still struggling in terms of emitting light that is supposed to illuminate a surface. Think streetlights, that happen to be my profession. LED's has been around in public lighting settings for around a decade and a half, two if you count the flat out useless prototypes that spoke promise of a better future, but really wasn't any good. The problem with them is that their efficiency is highly depending on how well you are able to aim with the light. That the reflector is state of the art. Optical lenses. That kind of thing. You literally need to concentrate the light where you want it to the point where it's awful to the eyes to look at the fixture when it's powered on. It has...sort of overturned the entire business in terms of lamp post placement and lamp post height. Because the older technologies where...more gentle to the eyes. And, as a result, more fitting to use in heavy traffic situations. If your streetlights makes drivers blind by accident, you'll have to do without the lights. It's a pretty obvious flaw of the technology. It didn't help either that the consumer introduction of LED's came at a time when streetlights had just had their - so far - most important upgrade; the high pressure sodium bulb. You have probably seen them. When the streetlights has an orange-yellow-ish glow, and everything they illuminate looks grey and dark grey, that's sodium. Either High pressure or low pressure, though high pressure sodium is the one with the better cost for maintenance. HPS has it's problems. It's a gas. That, you know, runs out. The bulb has a hint of mercury in it, which makes it expensive to dispose of it. Not to mention that it's *important to dispose it properly*. And every single bulb needs to have it's power consumption controlled so that it won't overheat and deplete the gas stupid fast. Despite that, the HPS took the market by storm when it arrived. It, I kid you not, cut power consumption to a third compared to the mercury vapor bulbs it replaced in the early 90's. If you have ever paid the electricity bills for a set of streetlights in a city with a million people in it, you'll quickly see the benefit of a technology that cuts your consumption to a third. If, you know, if you could live with the ugly grey streets at night. Most public owners definitely could. That is where the LED's tried to stomp in and take over the entire market. LED's are running somewhere around 100000 hours (roughly 25 years) before you need to replace them. HPS does 16000 hours with conventional bulbs (there is a hack for that, that also has it's problems) and needs to be replaced every four years. So, yay. Lower maintenance costs. What is there not to like? Well, for a start, when LED tried to introduce itself on the market, the power consumption was near-double that of HPS. If you want to convince someone that they want something expensive, new and unproved, that also cost more energy, you have to sell it to those who have awful maintenance first. And that is not streetlights. LED quickly became what you use high up in towers. As markers on bridges. Seaway markers. You know, places where they are a true pain in the ass to maintain, and you would rather just set it up and forget about it for a very long time. LED's have improved a lot over the past 15 years, of course. But, seriously. They are just now reaching kind of the same energy efficiency of HPS. Which means that LED's are not that awesome. They win the race in terms of maintenance, but not really in terms of energy. Yet. They are totally getting there, and it's close now.",
"It's not really that LED lamps are really efficient, but that conventional lamps are really inefficient. Traditional light bulbs make a little piece of wire so hot that it almost burns. This creates a lot of heat. Similarly, using a candle or fire creates a lot of heat and a little bit of light. The energy required for creating this heat is wasted if all you want is light. LED lamps have a more efficient way to convert electricity into light. Here is a detailed article about the efficiency of various kinds of lamps: [Efficiency of LEDs: The highest luminous efficacy of a white LED.]( URL_0 )."
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9dfjvg | How are blacklights made and how do they differ from normal lights? | Technology | explainlikeimfive | {
"a_id": [
"e5hd1n6"
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"text": [
"Blacklights simply put out UV (Ultra Violet) light, a wavelength that is not visible to the human eye. Blacklights often out out purple light as an indicator that they are active, and possibly as a bi-product of shining in that range."
],
"score": [
11
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