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dmddax | What is the Tor network and what should /shouldn't I be using it for? | What is the Tor network and what should /shouldn't I be using it for? From what I gather, Tor network is not a secure internet, it is *another* internet. How does one pull off such a thing on the same infrastructure? Does a person doing regular internet stuff need to know how and when to use it? Will using it put you on a watchlist somewhere? | Technology | explainlikeimfive | {
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"It is not illegal to use it, and nobody will put you on a watchlist. Except if you're from a country where it's banned like China, but I assume you live in the US. The network works, by sending your request on a different computer, from there to another computer, from there to the website. For example if you google kittens, it will go through several computers worldwide, where the path from one to another is encoded, so it's especially hard to crack, and, every station just knows the station before and after it. Google will send the results for kittens to the computer the request came from, this one also sends it back until it reaches your computer again. You can pretty much use it for anything, for example to look at porn, if you want to stay anonymous or if you don't want Google to know, but you can also reach these illegal websites, which operate through the anonimity of the Tor network. Note, that at least in my country, if someone knows for the US, can you pleas comment it, it is not illegal to look up these sites, and to surf on them. It is just illegal to operate these sites, like empire market, which is like eBay for criminals, to sell or buy on them, even if the thing is legal, it is a black market, so it is tax evasion, or to post something illegal like child pornography on a dark net social media site. If you want to know how to get to these sites, there is a wiki in the dark net, you can look up on Google how to get there.",
"> From what I gather, Tor network is not a secure internet, it is another internet. How does one pull off such a thing on the same infrastructure? Tor is still the same internet, just now when you connect to anywhere the data packets are bounced around the world with an 'onion' of encryption layers on them. - You made the encrypted bundle and send it to the entry node - The entry node to Tor knows you, the encrypted bundle and the next node - All the middle nodes only see encrypted bundle, where it came from and where its going - The exit node (where Tor connects to the regular internet) sees the unencrypted data (well, no Tor encryption, it might still be from HTTPS or whatever), where you are connecting too and the node that handed it that data. - Then that goes in reverse for the reply if the website or whatever gives one. The 'another internet' understanding might come from websites you can only connect too via Tor, which do exist. The purpose of these is they live inside the Tor network, so you never have to leave Tor and its security to communicate with them. This is good for anonymisation because one of the main ways to identify a Tor user connecting to the regular internet is traffic correlation. Joe Smith connected to Tor at this time and 5s later this server we think he is involved with got a request from a known Tor exit node, wonder who that could be. > Does a person doing regular internet stuff need to know how and when to use it? Not really, Tor as a security measure is kind of at the level where you are trying to protect yourself against dedicated surveillance or attack by sophisticated attackers (eg, hacking groups, nation states, big business). Its not necessary for the average person because sophisticated attackers are very few, regular people are very many and not that interesting to sophisticated attackers. If you are concerned about remaining hidden from advertisers and such there are much less intensive solutions for that. Though the people who do genuinely use Tor to protect against these threats would love for regular internet users to use it. Regular people using Tor for their regular ass traffic would be akin to a continuous avalanche of hay to hide their needles in. > Will using it put you on a watchlist somewhere? Yes, or at least you should assume it does. Your connection to Tor entry nodes is not hidden unless you are taking the additional step of connecting to a VPN first, so ISP's and the like know you are connecting to Tor, its just from there they have no idea whats happening. Obviously connecting to Tor is not typical for an average person, so there is a good chance the people/IP's that do are being put on a list somewhere. That list would be huge and functionally useless, see above with needle and haystacks, but if you are the NSA why not make the list, storage is cheap.",
"Tor is a networking system. In simplicity, the main differences between it and standard networking are: 1. Tor uses several \"layers\" of encryption when sending data, much like the layers of an onion (Tor is actually short for \"The Onion Router\"). This means that if said data is intercepted along the way from A to B, it is harder to decipher than unencrypted or single layer encryption data, which means you're a bit more protected. 2. It sends data across multiple \"nodes\", which are all computers set up running Tor software, essentially like a \"tor server\". When starting Tor, it will generally connect you to a series of nodes that is a different set than last time. This is not entirely different from standard networking, but in Tor, the nodes only know the last node and the next node. So if my data is intercepted at node 4/9, whoever took it (if they can break the encryption) will only see that it came from node 3 and is going to node 5, they won't be able to easily see that it originated from me. This is beneficial for anonymity because it essentially 'erases' your paper trail for where the data is going and coming. (Not 100% accurate, but eli5) 3. It also breaks the data down into seperate pieces, and sends them through different \"tubes\" on their way from A to B. This is easiest imagined as a literal band of tubes together, and you take a jigsaw puzzle, and drop each piece through a different hole than the last. That way, if someone was to cut a whole in your pipe and take the data (puzzle pieces) out, they would only have a few pieces that don't really make sense alone, and they almost certainly wouldn't be able to extrapolate what the whole picture is. 4. You can access .onion sites, which are Tor only websites that cannot be accessed by standard browsers, I.e. Chrome, Firefox, etc. There are some of clearnet sites that have .onion servers, for instance the journalistic website deepdotweb has a .onion page. However, most use for them *is* for nefarious purposes, such as pornography (legal and illegal) and drug/weapon selling. 5. At least in the USA, it is not illegal at all to use Tor, to browse with Tor, or even to look at drug selling websites. It is illegal, however, to view child porn/any other illegal porn, to buy things off a drug market, etc. Basically, if it's not illegal porn, it's not illegal to look (in the US.) 6. It won't put you on a \"list\". The NSA has a shitload of illegal spying going on on us already, they really don't need different \"lists\". Much more practical to just have personal dossiers anyway. The biggest downside to Tor is that, due to breaking down and going through those tubes and all those seperate nodes, it's fucking **slow**. Even if your net is good, it's slow. Not practical for just laddy-da web browsing. If you really want to explore it, especially if you're going to make any practical use of it (which, as a disclaimer, I cannot support or condone), you need to use a TAILS flash drive at minimum for any realistic security. Also, inb4 \"DoN't UsE tOr It'S cOmPrOmIsEd\" You motherfuckers that say that are actually retarded. They have so much spying on us they don't NEED to infiltrate Tor to see what we're doing if they REALLY want to. The ISPs will cave and give them what they want. The thing is is that they can't use it as evidence against you because they would have to admit how they got it, don't wanna ruin the gravy train. Besides, they REALLY, REALLY, DON'T CARE about the guy buy a little bit of weed or Xans online, they want the dealers, the suppliers, just like literally every other drug agent. *With that being said, if you're looking at drugs, most of the markets have gone down and the confidence in the ones that remain are pretty sus outside that."
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dmhkro | How do you get oxygen on a submarine? | Technology | explainlikeimfive | {
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"Basically there's a few ways. Either oxygen generators, which is done through the electrolysis of water, separating the oxygen out of the water, pressurized tanks of compressed oxygen, or chemical reactions which release oxygen as a byproduct. The Carbon dioxide problem is solved by using things like scrubbers, which traps the CO2 in a chemical reaction. Obviously, these are all limited supplies, so that's why submarines can only stay under for so long and sustain a crew. Generally speaking, 90 days is the average they stay under.",
"There is two types of submarines, diesel and nuclear. Diesel submarines do not have much power and what little they have is used for propulsion. So they have to bring their oxygen in the form of pressurized bottles. Alternatively they can bring \"oxygen candles\" which is simple canisters of a chemical which produces oxygen when it burns, mostly used for emergencies. Nuclear submarines on the other hand have an excess of power and can power the electrolosys of water to generate oxygen from the ocean directly. This allowes them to theoretically stay under water for decades until their supply of nuclear fuel runs out. However in practice they also need food and maintainence so can only stay under water for a few months."
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dmks21 | How does cold make electricity move easier, and how does it cause superconductors to have 0 resistance? | Talked about it a little in my engineering class, and my teacher said that when he tried reading a scientific paper about it, even he was struggling to understand it, I thought this would be a good place to ask about it | Technology | explainlikeimfive | {
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"I do not know why cold makes resistance decrease, but I can give you a rundown on superconductors which are their own process. Basically when electricity heats up a material, it does so in discrete quanta (packets of energy). If the electricity does not carry the right sized packets, it cannot dump them as heat in the material. In superconductors, electrons couple together into cooper pairs, which causes them to carry excessively large packets of energy that they cannot dump into the material. These pairs are not very stable, and the jiggling of heat splits them, resulting in superconductors requiring low temperatures to sustain these pairs.",
"Consider the temperature of a material as a way to measure the how fast the atoms jiggle. Higher the temperature, more the jiggling. Electricity is the flow of electrons inside a material from one end to the other. Imagine you are in a crowded room with people moving randomly. You need to get from one end of the room to the other. The faster and more random the people move, the more time you will take to reach the other end. Here, you are the electron and the people are the atoms. The people are providing resistance to your movement. Now if these people slowed down, or stopped, you could quickly move through the crowd and reach the other end. The slowing down of people is analogous to the lesser jiggling of atoms due to lower temperature. When your path is resistance free, it is called superconductivity. Superconductivity occurs at extremely low temperatures for this very reason. I hope this helps."
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dmpqlr | Why do Windows Updates need to be installed in two phases, namely when shutting down and booting up? Can it not be done together in a single phase? | Technology | explainlikeimfive | {
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"Windows locks certain files while the operating system is in use, and such files can only be modified when they're not in use (such as while booting up).",
"Installing updates on a running program is a bit like trying to perform maintenance on an engine while it is running. You spare yourself a lot of pain if you shut down the thing before you work on it. This is fine for most program, but you run into problems with the OS. You need the OS to run to do anything at all, but you can't really do the thing you want to do while it is running. There are complicated solutions to that, but Microsoft mostly goes with the simple approach of preparing everything while it is running shutting down and then during startup before everything is fully running again taking the pre-preared stuff to finfish the job.",
"While we are at it, why hasn't Windows joined the modern world and update without reboots, like Linux does? Linux can even update the kernel, with only a slight pause (a few milliseconds).",
"Let’s say you’re trying to change a pair of pants. And pants = Windows version No pants worn = computer is off Let’s say your new pair of pants have just been washed and they’re in the yard. Your old pants also need to be washed (Windows needs to remove old files) and they must be washed in the yard. You must first go collect your new pants from the yard, (can’t be naked, so you’ll need to wear your old pants out there) and bring them into your room where you put them somewhere you’ll remember so you can take it and put it on after you’re pants-less. Now, you gotta start stripping (shut down). Then put on the new pants (boot up), but before you can do anything else, the old pair of pants need to be put in the wash (finishing updates) which you carry back out into the yard in your new pants. That’s as decent of an analogy I can come up with."
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dmu0fl | How on earth do weapon suppressors work? Do they really decrease penetration/range potential of a bullet? Without it overheating, how long would it take for it to break? | Technology | explainlikeimfive | {
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"Suppressors work like car mufflers. They capture the explosion and expanding gasses. They do not actually effect the projectile. Suppressors are actually built quite solid. I recommend lookin up iraqveteran888 on YouTube for a more knowledgeable souce."
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dmw1st | Why do car speedometers show a different speed to GPS? Which one is correct? | Google maps now shows speed. I set my cruise control on my car to 70mph on the motorway, but the GPS says I'm only going 67mph. My dashcam also records speeds and says I'm only going 67mph. I get a lot of hire cars for work when I need to travel, and it seems to be the same on all of them. GPS always says I'm going a few mph slower than I actually am (or is my car speedometer saying I'm going a few mph faster than I actually am?) Edit: corrected spellings. | Technology | explainlikeimfive | {
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"Your cars speedo works by estimating your speed based on the revolutions per minute of your wheels multiplied by the circumference of your wheel. As the circumference of a wheel can vary due to different tires, inflation etc, the speedo tends to err on the side of caution and over estimate. Also, legislation typically requires that the tolerance of a speedo be within a few percent, but not under report the speed. So they report over. This is so you don't inadvertently speed. A GPS calculates your speed by noting how far you travelled and how long it took, and dividing the two. This is typically more accurate as it's not subject to as much variance as the previous way.",
"Provided you're driving straight on relatively flat ground, the GPS is likely the more accurate device. Vehicle speedometers are calibrated for a particular distance per revolution, which can vary if you change your installed tire size, for example."
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dmwlal | How are hackers able to gain access to people’s personal accounts? I’m assuming that they don’t individually type in thousands of different passwords, right? | Technology | explainlikeimfive | {
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"Hollywood has taught people that hackers use super complex tricks and tools to hack into computers. But in reality, it's usually just some dude posing as local IT or some sort of trustworthy person and asking for passwords. Why spend hundreds of hours looking for a weak spot in their security when you can just trick Karen from HR to give you her credentials? Hackers will also cycle through lists of emails and known passwords. Unfortunately, many people still use horrible passwords such as \"qwerty\" and \"123456\". So they will just program a bot to go a site like Facebook or Twitter and try a bunch of those passwords with known email addresses. The bot will make a list of all email and password combos that work. Most of the time, these hackers will sell them to other people who use them for spam. Lastly, Keyloggers are a less common, but very effective way to get your credentials stolen. Installing suspicious programs can sometimes include hidden payloads that contain keyloggers, a malware which records everything you type and send it to a hacker.",
"There are lots of different ways. Most of them boil down to using a computer program to automate the process of trying different passwords until one works. This isn't always the case though. Occasionally there are bugs in software that can allow a person to take over an account without the password. Phishing attacks can spoof a legitimate site and trick you into just straight up giving them your password willingly. Some companies store passwords in plain text, which removes the step of cracking the hashing algorithm or guessing the password altogether. There are even attacks where people can hijack a cookie you generated when you logged into a site and use that to gain access without your password. There's lots of different ways to do it, just do some reading, it can get quite interesting."
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dmwmrp | What is SAML and how does it work? | Technology | explainlikeimfive | {
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"SAML is used to provide federated authentication, essentially a digital passport. If I want to provide a service lots of different people can use, I need to be able to know who they are, especially if I am storing things for them. The traditional way to solve this is creating an account for each user with a username and password. This can be a pain to manage, is annoying for users to have a million different accounts, and can be a security hole. It can also be difficult to work into low-level services that operate below the user level. SAML is a way to offload the identity management to someone else. You are essentially saying, \"Hey, Facebook, hey Google, I got this user who says you know them, here is the username and password they gave me.\" That organization is acting as an identity provider, validates the person does have an account with them and issue a token in response that acts like a visa. For subsequent requests, you just show that token and are let right in."
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dmxpfy | How does opacity of digital images work? | Let's say I've got a pixel which is pure red. Would putting a pure blue pixel over it with 50% opacity result in a perfectly purple pixel? Feel free to explain on an example using http color codes. | Technology | explainlikeimfive | {
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"> Would putting a pure blue pixel over it with 50% opacity result in a perfectly purple pixel? [Yes it would]( URL_0 ) Putting a layer on top of the background and setting it to 50% opacity blends the two layers together at 50%, meaning half-way between red and blue, giving you purple.",
"That's not really an opacity question, just a blending question. Here's a linear interpolate: Result = A * Blend + B * ( 1 - Blend )"
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dmy8qc | What makes certain computer programming languages more suitable than others for writing certain software? | There are many different computer programming languages used to write pieces of software but what makes one language more suitable for writing a certain program than other languages? | Technology | explainlikeimfive | {
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"There's LOTS of reasons. Some languages give the programmer lots of control over how the computer uses it's memory. For things like video games, that can be very useful because they are memory intensive. Where as automatic memory management can be very helpful it's often not the MOST efficient way. Some languages can be used across many operating systems, other languages cannot. As a general rule, a language that is dedicated for a specific operation system will be more efficient, but less flexible. Java for example can be made to run on almost any operating system, but it's very inefficient (tends to run slowly). That's really useful if you want to make a program that can run almost anywhere, but not useful if the program is highly resource intensive. Programing languages also have little add on packs. Some of these add on packages are better than others. So if you want to make a video game that uses a certain kind of graphics, you might select a language because it's really good at that kind of graphics. But when it comes to making another aspect of the program another language might be better because of the add ons that are available there. So the key choices are what kind of OS and device do you intend to run the program on. What's the program for and is it going to be resource intensive or not. Lastly are there any helpers or add ons that you want to have access to.",
"Sometimes it's because the language is built specifically to be a tool for that type of project, other times it's because of some underlying aspect of the language that makes it more or less appropriate for something. A few specific examples: Python is often recommended as an appropriate language for beginners because a lot of the syntax is words rather than the symbols common in other languages. For example, instead of \"if (!a & & b ||c) Python would have \"if not a and b or c\" which is easier for someone not well versed in programming to pick up. Javascript is the primary language for front end web development because it's the language that web browsers expect. There are other options (like Actionscript for Flash) but they usually involve using a web page to run a standalone executable written in something else. Javascript is the only language you can just hand to a web browser and it will run. Objective-C and Swift are the main languages for iOS apps because they're created and maintained by Apple for that specific purpose. You can write iOS apps other ways, for example I've seen iOS apps that used a lot of C++, or that just ran a web view and did all the work with Javascript, but doing it that way won't give you access to the full range of options available in Obj-C and Swift. For example, an app built with HTML can access the camera, but can't map live input from the camera directly to a layer within itself like an Object-C or Swift app can. For a more complex example, and one that's not just \"it's the language for this because people made it to be,\" C++ is the primary language for mainstream video games because it's very fast. Speed and efficiency are important for any software, but they're *especially* important for video games which have to run a lot of code over and over and where a brief delay can adversely affect the user's experience. If you make a calculator the calculator only has to execute code when the user presses a button, so if you have an inefficiency that adds a millisecond here and there it's not really a huge deal. On the other hand, if you have a slight inefficiency in a line of code that's run 60 times a second for every object on screen, that starts to add up. The reason C++ is so fast is that it doesn't do a lot of under the hood stuff other programming languages will, such as array bounds checking or garbage collection. If you create an array of length 10 and try to access index 20 most other languages will check and throw an out of bounds exception, but C++ will just let you do it. Many languages also have garbage collection, meaning they will count references to an object and remove it from memory if nothing is pointing to it anymore which helps prevent memory leaks. C++ doesn't do this, which means developers have to manually manage allocation and deallocation of objects. Consequently, C++ is a more challenging language for beginners, but much faster when executing lots of code."
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dn2n2c | How does a vinyl record store audio?? | Technology | explainlikeimfive | {
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"Because sound is vibration. So, a microphone just vibrates with the air and that movement is captured and amplified by the electronics. All you need to do to create the sound again is vibrate the air the exact same way. If you take a speaker and a microphone apart, you'll see that they're the same concept: air vibrates a membrane which vibrates a wire near a magnet, which creates electricity with the same vibration frequencies as the sound. Needle vibrating on vynil, magnetic oscillations recorded on cassette tape, or a laser passing over pits in a music CD to \"vibrate\" the reflected laser beam, all of these get converted into electronic frequencies, which then the speakers or the headphones vibrate the air and create sound again. And your ear drums pick up the air vibrations and convert them to nerve pulses, which your brain then interprets as music or language with meaning.",
"It's literally a mechanical translation of the sound received into physical form. In the original phonograph, a needle was attached to a thin membrane/diaphragm and was moved along a wax cylinder. As sound hit the diaphragm, it moved, moving the needle with it, slightly changing how the needle was cutting the groove into the wax. For playback, the needle was run through the groove again, but this time, the needle/diaphragm was connected to a amplifying cone. As the needle ran over the grooves, it vibrated the diaphragm, producing sound that was then amplified as it traveled out the cone."
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dnbjxo | Why are phones calls’ bitrate so bad? Why is Discord crisp and clean but phone calls are low quality? | Title | Technology | explainlikeimfive | {
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"When the telephone system was first invented the technology didn't have much bandwidth, so they limited the range of frequencies that where captured and transmitted. They were focused on intelligibility instead of fidelity. It persists today strictly for compatibility reasons."
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dnc45u | in space movies, how do they make it look like the actors are moving around in zero gravity? | Technology | explainlikeimfive | {
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"There are a couple of ways you can do it, but I'll share what Gravity did (because they did it really well). First, every object is computer generated. This is going to take a lot of time, and it means things aren't going to be able to be changed very easily. It also means that actors can't improvise or make little changes to the script or blocking, because then the computer guys would have had to spend hundreds or thousands of extra hours fiddling with things to make them work again. Second, they put the actors into suits and had them dive underwater while on suspension wires. The wires keep them held under, but they can still move about a bit to simulate movement in zero G. They had puppeteers working the strings to make them look natural. This is the more expensive and time consuming method of simulating zero G, most movies with any kind of budget will instead use parabolic airplane flights. Third, a very complicated lighting rig that they called \"The Light Box\". It was a 20-foot-high box enclosure with over 4,000 computer programmed LED bulbs. They had robotic cameras capture the close-ups, and the scenes where actors were \"spinning out of control\" or moving very rapidly were actually very rapid still frames while those 4,000 bulbs blinked in such a way that it created the illusion of movement. This is actually a very important and ingenious invention that Emmanuel Lubezki and Tim Webber created for the movie that will probably be seen in a LOT of movies to come. It allows the actors to see what their characters are supposed to be seeing because the computer guys can project images out of the bulbs, and it allows for the exciting footage that you see in the film. Finally, the post-production team blends it all together after the fact, removing the wires, rigs, harnesses, adding the computer graphics and the other special effects so seamlessly that you can suspend your disbelief enough to think the actors actually are doing what they're doing on screen. So much so that you don't actually notice that Sandra Bullock's helmet and visor are actually just computer graphics while you're looking at her face.",
"A lot of it is CGI. Cables removed afterwards. Sometimes, like in Apollo 13 they are actually in zero gravity. They built a set inside a ‘vomit comet’ plane that astronauts use for training. It goes to a very high altitude then does a steep dive. While in the dive, people inside experience a few minutes of zero G.",
"There are a number of tricks. A common way today is to hook people up to wires and zip-lines so that they are halfway between being acrobats and marionettes and have them move around in 3D and later remove the wires with CGI. Of course CGI wasn't always a thing and isn't always the best solution even today. One way to get genuine zero-G for very short periods is to simply film inside an airplane accelerating downwards at 9.81 m/s², you can film that and have realistic looking zero-g effects because that is exactly what it really is. NASA has a plane built just for that and they occasionally rent it out to whoever. It only works for very, very short periods though, because you can only be in freefall downward for so long before you run into the ground. You can do a lot with clever cuts and perspective, where you only show part of an actor or filming them from an unusual angle to get people to believe stuff. Like one shot only shows the lower body floating above the deck (while out sight of the camera the actor is held up from above), then switching to a show showing the unsupported upper body (but not the legs standing on the ground). and so on. Combining different methods helps a lot. Of course all that is pretty expensive. One memorable cheap fx shot to simulate zero-g was the opening of the movie \"Barbarella\" where the title character strips out of her space-suit in what is supposed to be zero-g inside her shag carpet wallpapered spaceship. They achieved this shot by simply filming from the ceiling and having the actress roll around on the floor pretending to be floating in space. A lot of getting you audience to accept that your setting is in zero-g is not in having the best effects of being scientifically accurate, but in simply being bold and convincing enough and maybe being able to distract the audience with some naked skin.",
"Same way you feel like you’re floating going down a roller coaster, except they are doing it in planes. They do controlled free falls."
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dnhxjn | How do you use Hexadecimal code? | I'm watching the Martian and he's using Hexadecimal code to speak to NASA. Why is he doing this and how does it work? Edit: Could iI get an explain like I'm a newborn? Because I still don't understand. How can you get the full range of the alphabet from 0-9 and A-F? | Technology | explainlikeimfive | {
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"ASCII tables are an agreed translation that relate a count to a character. If you wanted ro say \"HI\" an ascii table says \"H\" is 72, and \"I\" is 73. but ascii tables show lots conversions, instead of decimal 72, you can use hexadeximal 48, or binary 0100100. These values are all the same, it is just changes how we display them. you could use any method to communicate but in the movie i believe he explains a little bit that he selected hexadecimal because it only uses 16 characters 0-9 plus A-F which is easier than english 26 letters plus characters. Also, hexadecimal is very clearly \"yo, i am using computer speak!\" to anyone who uses computer speak, in this case NASA.",
"\" How can you get the full range of the alphabet from 0-9 and A-F? Remember in elementary school when you made that super cool secret code where A = 1, B = 2, C = 3 e.t.c? Computers do the same thing. A = 42, B = 43, C = 44 e.t.c. One of those standards is called ASCII. Mark only has 0-9, A-F. If he want's to send \"M A R T I A N\" he'd first use the ASCII table to convert that message to the numbers 77 65 82 84 73 65 78. From there he can then represent them in HEX to get 4D 41 52 54 49 41 4E. NASA can then go in reverse, translating that to MARTIAN and reply."
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dniiqn | How does Google photos separate photos into such specific categories without them being labeled manually. | Technology | explainlikeimfive | {
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"With machine learning. A computer program has looked at many many images that _were_ labeled, and it learned from them what sorts of labels to put on other photos. It learned by looking at an image that people had labeled but not looking at the label, guessing a label and then comparing the result with the label given by a human. Then it made a note of whether it was right or wrong. Doing this many times with many different images it learned to label automatically.",
"If lots of people have already tagged photos of cats with the word. ‘Cat’, then the Google Machine automatically starts Learning ‘this new photo looks really similar to all those other ones that are tagged as cats, so it’s probably a cat’ Also, Google knows where most photos were taken. And Google knows where most places are. So if it can see the photo was taken outside Buckingham Palace, and the photo looks like a palace, it’s probably going to be Buckingham Palace.",
"I've seen a documentary relating to that not so long ago, a french tv-investigation program about \"algorithm bosses\", like Uber and Google. From what I remember, the algorithms/AI don't entirely learn by themselves. There are websites that offer freelance tasks to circle objects and such in pictures, and identify them, so their algorithms can compile all the infos and sell the data to big companies. It was a very interesting and shocking documentary, people are paid almost nothing for those kind of jobs. Documentary (in french) : [ URL_0 ]( URL_0 )"
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dnjre9 | What is a national intranet that Russia seems to be doing? What makes it different than the internet? | Technology | explainlikeimfive | {
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"What makes it different that it will be autonomous , at least in theory. As russian gov says, they want network infrastructure independent from global web, so if someone (read america) decides to block their access to internet, their infrastructure would not be affected or would have backup network to operate on. Edit: they don't have to make new infrastructure from zero. Same wires, towers and protocols can be used. All they need is just new servers for websites, online services, ip-phones, card readers in stores, video cameras and i guess software/hardware to replace all this. So when nodes outside russia start bouncing request, they can switch to intranet. This is my take on their claims and reasons for intranet. For all of you concerned about freedom of speech, i say don't worry. It is already non existent in russia."
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dnkjgf | On a shared wifi connection (university dorm), can someone else downloading movies or having a virus on their computer slow it down for everyone? Why? | Technology | explainlikeimfive | {
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"Imagine having a pipe that can carry X ammount of water per seconds. Now many people are drinking from that water but if for some reason one of theses person start drink 100 time more water the other person will have less water to share (pipe cant deliver more water than a given ammount per seconds) and thats as simple as that",
"Yes, because the WiFi network and the internet connection are both limited in \"speed\". If one computer has a virus that's poorly written and uses a lot of \"speed\" that means the network slows down for everyone else. There is no difference between computers downloading movies which slow down each other and a virus propagating itself or just continuously searching the network for something to infect. Friend downloading a movie takes away \"speed\" from you the same way a virus does. Both activities use \"speed\" and it's always finite. (Speed = bandwidth)"
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dnm5rf | What happens when you change the dial of an FM radio? It takes 2 seconds to match something. Is it the frequency, is it digital? | Technology | explainlikeimfive | {
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"It's digital. In the \"old days\" like pre 2000 this never happened. Radios turned their dials instantly and you got whatever channel you turned to. Today things are a bit different. There's song titles coming though that display on screen. There's still all the old stuff, but there also new stuff being broadcast and it takes a second for new radios to get all that and output. There's probably room for improvement. Like they could output the music immediately and then delay the rest, including any hd audio. The output would be slightly degraded, but for only a second and I don't think anyone would mind if it came in exchange for speed.",
"On a \"modern\" radio, the tuner is on a chip, so there is likely some lag between the chip tuning to the new frequency and then validating that it's acquired a signal or not. There *are* digital/HD FM encodings as well, so part of that delay might be checking for those as well. In the olden days, you could hear the new frequencies as fast as you could turn the actual, mechanical dial."
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dno7g3 | when using machine learning to teach a computer to finish a game, how does it determine intermediate goals? | I've seen machine learning used to play fairly complex games like Super Mario. How would one set the 'successful' condition in a fairly long game, i.e. you have to go through several worlds before finally beating a boss and ending up in some end game screen? And how does the learning algorithm know that it's making any progress towards that final goal? So how would it know that world 4 is closer to finishing than world 2, or even dying repeatedly? | Technology | explainlikeimfive | {
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"This is one of the difficulties of making a machine learning algorithm. In the case of, say, Mario, you might set the goal as \"go far to the right\". The farther right it goes, the better it thinks it did. Or maybe there are keys in a level - you tell it to get closer to each key in order.",
"In very simple terms, you would set up the machine with a few simple rules and then let it run. You can tell it that the end goal of Super Mario Bros is to get to the end of level 8-4 without dying, and that it must complete all the levels in between 1-1 and 8-4 in order to be successful. You can give it certain parameters and let the computer do the rest"
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dno87d | how do online password managers work and how do we know the companies that run them can't just access our accounts, specially sensitive ones like online banking? | Technology | explainlikeimfive | {
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"This is the ELI5 version: They actually don't know your passwords. Imagine you want to store some important information in your bank. You could just give it to them and trust they won't look. But what if they do? Or what if the bank gets robbed? So instead you lock the information in a box and save the key at home. Then you give the box to them. They can safely store the box but they don't know what's in the box. So when you need the information you tell them to send the box to you. Then you open it with your key, look at the information, put it back, lock the box again and send it back to the bank. But how do you know the bank can't just open the box with brute force? Well the box is made up of a very strong material, lets call it Cryptonite. This is so strong it is practically impossible to break it. Technically you could break it, but you would have to drill for BILLIONS of years until it actually breaks. This how a GOOD online passwords manager works. So make sure you chose a well known service. & #x200B; Edit: As many have asked, how do you know this is how the service works? When you use a online service that handles your passwords there will always be some level of trust involved. They can be lying or they can have vulnerabilities/bug in their software. A online password manager delivers two services. One is designing the box, the other is storing the box. And when their methods is not completely public, i.e. Open source, you can never be 100% sure it is secure. So as many have suggested in the comments, use two services to achieve the same URL_4 continue with the analogy: Since the bank won't let you know exactly how the box works, you don't want to use their box. Luckily there are box-experts out there that have designed boxes that are completely unbreakable. Also they will tell you how YOU can build them all by yourself, completely for free. So take their instructions and build the box and save the key somewhere only you know where it is. Or if it's a combination lock, just remember the combination. The you can tell the bank to store the box and you can be 100% sure they can't open it. To leave the analogy, use [KeePass]( URL_3 ) to encrypt your passwords, then save the encrypted file(s) on [Dropbox]( URL_1 ) or [Google Drive]( URL_2 ). This is completely free. & #x200B; Quantum edit: One thing that most people get wrong about quantum computing and cryptography is that they can (in the future) break public-key encryption, not symmetric encryption. The example in my analogy uses symmetric encryption so it will be safe against a quantum-computer-attack. Maybe I have to make the key longer but it won't break the encryption. [Post-quantum cryptography]( URL_0 )",
"They never get to see your actual username and password for any of your accounts. The way this works is that your master password is used to encrypt your usernames and passwords for other sites before they're sent to be stored by your password manager, and your master password itself is never sent to your online password manager. So, all your online password manager has on their servers is the encrypted version, with no way to decrypt it - the only way to decrypt it is if you know the master password, which never leaves your computer. Of course, this is based on how they say they do things, so you might also wonder how we know that they're doing what they claim - the answer is that plenty of security researchers have looked into these services and tried to break them. There have been some minor issues published, but the basic premise that I described above is actually what they're doing, and if it weren't, that would have been published.",
"You can never be sure. Lastpass for example actually recently had a problem with exposed passwords: URL_0 If you want to be safe, use a well known offline password manager, and handle the storage yourself.",
"Basically, your information that gets stored on their servers is scrambled in a very specific way using a complicated equation. Simplistically, think of it as distilling your vault password down to a number (we'll use 4), your website password to another number (let's say this is 5). Multiply those and store the answer (20) in the vault server. This is the \"hash\" of your original password. In reality, this ends up being a string of hexadecimals (0ffa62b4c725ca....) Because of the actual complexity of the math that created the resulting answer, one can't easily figure out which numbers created that answer. But for the sake of the oversimplified example...if you know that the answer is 20, and you supply your vault password which was 4, you know the original password that you stored was a 5. So when you go to a website and have it fill in your stored password, your browser asks the vault for the password hash for this site. Your browser already has your vault password since you logged into it. It now has the two pieces of information it needs to figure out the missing information, which is your original site password. Anyone can see your encrypted password and it doesn't help them one bit to figure out the real password unless they have your vault password - the \"key\" to unlock/decrypt it.",
"Think about when you goto the gym, you may have a locker with a lock where you set your own key on it when you arrive. The locker is stored at the gym, but you can access it and put your stuff in it for safe keeping, but the gym can never access it because they don’t have your code. You can get your stuff out whenever you’d like by entering that code and use it as you see fit. This isn’t a perfect example because ostensibly the gym would have a master unlock, but it gets the point across to a 5 year old.",
"If the company is doing it right, they are storing your passwords in an encrypted format so the can only be accessed by someone who knows your master password, which they never store. You have to find a company you trust, which isn't as hard as you might think. Stealing from bank accounts is very illegal, and it is unlikely the company would get very many before they were caught. They'd much rather get subscription feels from million people than try to steal from a few hundred. It is really a question of balancing risk. What is more likely, a company that is in the business of security having a serious breach, or you personally getting hacked because you are using the same crappy password in ten different places?",
"When you make and account you get a locker. You can access that locker with a master password. Once inside the locker, everything is encrypted. They cannot read what ever password you type in. It's similar to the end-to-end encryption in Whatsapp they can't read your messages. The passwords are stored in encrypted format in your locker. When the password managers are hacked and the hackers have access to the locker when they open it they don't see passwords, they only see encrypted passwords which are extremely hard to decrypt.",
"Unfortunately this thread has too much momentum for this to make headway. Technically any of these services can be vulnerable. Even KeePass which allows you to \"lock the box\" before uploading to the cloud has rhe vulnerability that developers need to maintain and update the software. If a developer gets hacked and someone pushes malicious code it's arbitrary to steal your \"key\" to unlock the box. You are trusting several layers of entities whenever you do anything with trust online. LastPass as an example You're trusting the browser because it could steal your credentials as you type them into the site. You're trusting LastPass as they develop the JS front end logic, the back end server processing and at either point they could try and \"shim\" on software to steal your goods. It goes even deeper than this! You trust the operating system you are on! (Think unpatched Samsung Android). You trust the cryptography library writer for that build environment. LastPass might use the bcrypt library from Python or PHP which is the fancy \"locking mechanism\" people are referencing. However if the library writer makes a mistake you could be compromised. The last scariest truth is that the lowest level of trust in societ comes down to the mathematics of cryptography. If the mathematician/computer scientist who invented the cryptographic algorithm makes a mistake EVERY library, EVERY software that implements it the same is vulnerable. Every chain is a layer of HUMAN trust not technological. However the likelihood is slim for the average person. So it's safer to have one strong centralize password to change regularly and segmenting your password usage online. Doing it this way keeps your \"ship\" from sinking like Titanic by compartmentalizing the exposed passwords. If your FB has a different password than your bank, it isn't possible for them to login after they compromise your FB account.",
"To safeguard your data, there are 2 ways. * Encryption: let us assume you have a password like `123456`. If we take a strategy like increasing the count of characters by 1. Your password would now be 234567. Now for a character-based password like perhaps `hunter2`, this could now be `ivoufs3`. For a random person, if they see `ivoufs3`, unless they know the strategy here (example as above increase character by 1), you won't get the password. * Hashing: As per the previous example. Let's say your password is `123456`. Now if we divide this by 5, and only save the remainder (i.e 1), even if they know the strategy of divide by 5, it doesn't matter, as if I divide 11 by 5 or 12378543586 by 5, the answer is the same. What these companies usually do is combine your master password with a random string such as say your password is `123456`. Now on this, we add the random string so your password now becomes `H4KVO123456T3JPG` (a much more complex one). This is generally called as salt as this is to spice up the password string. (The more fancy-sounding name is Initialization vector). Now, we encrypt this ala above example strategy. So your encrypted password then becomes `I5LWP234567U4KQH`. Now if I take the ASCII representation of this it would be `073053076087080050051052053054055085052075081072`. And if I divide it by 5, the end result would be 2. I would then take this 2 and get the ASCII representation again (`050`). Divide by 5. Value = 0. If I do this a bunch of times and all I store is * the number of times I've done the operation, (2 as per above case) * the additional characters I've added - (H4KVO,T3JPG). * final result (0) Notice I do not really need to save your password. All I need to save is the operation conducted ontop of your password, and the final result from which I can never truly get the original password back. The next time you send a password, I can try to do the exact same operation on that password, and see if the final value matches. If it does, you are authenticated. To be clear, the operations are a bit more complicated than this and usually done with large prime numbers so you don't repeatedly get 0, etc. *So, using this. I can save a hashed version of your master password, and use that to unlock the box, that is your safe containing all the passwords. These passwords are then encrypted and not hashed(because you actually do want these passwords back).* Part 2 of your question would be: How do I as a customer know that the company is still saving these passwords, either in some random database or maybe in logs or something. This is basically done through different certifying agencies, which will be able to oversee the operation of the company and certify that they aren't doing anything hockey-pockey. Additional things to add. The data sent over the network would be encrypted - SSL or TLS (newest version is v1.2). This is so that, somebody who has access to your router (example: say you log in from work or school) would still only see some random gibberish and not really be able to get your password from it. The encrypting company may even initiate a logic of sending over an already hashed version over the network. This is basically to add more gates to mess with someone trying anything unwanted etc. (Although I don't think most companies would opt for something like this as it isn't really a tough one to crack, just an additional step is all).",
"Is there really a proper bank out there that just requires a single password to log in? Normally you need a gadget of some sort, a personal and unique code card or a verification app to log in. A single password like for an email account sounds crazy unsafe..",
"You'll never know. Unless if you're the one who created your own password manager, in which case your non physical issues are spyware, keyloggers, malware etc. Use password managers at your own risk and through your own research and analysis of which companies may be trusted. That said, having a password manager is infinitely better than reusing passwords. It's the same with hashed and salted passwords on websites. For something encrypted to be decrypted, you must have a decryptor/key. And this key is either or both located and generated on their location. You are trusting the locksmiths for the locks and securities of your home who issues you a masterkey who may or may not have a copy or blueprint of it and in this case, your master password.",
"I'm pretty sure, technically, they can/could (only offline managers couldn't), because they could make their app send your password to them. It's just that they wouldn't do this (say if you're Snowden and you use such password manager - pretty sure the governments could make that company get your master password/data; and/or the data those companies have can leak;) Not having the code of the app/program (open source) - basically you can't tell wether it **knows** your master password or not. You just have to \"trust\" that app/company. With an open source app/program people around the world can check out everything that app can do, and if they/we don't find anything suspicious - that app/program is safe. So it's only safe to use a program if you have sure it never has access to the Internet, or use a (well reviewed/popular/known) open source program (and a trusted server (such as created by yourself), and/or I believe there is such thing as open source servers (although I'm not entirely sure about that))."
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dnrmua | how ad blocker extensions identify ad elements on a webpage/video/stream and remove it? | Technology | explainlikeimfive | {
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"Users have created lists of sites/domains/ code that are advertisements. When a page starts to load it calls on those and the ad blocker filters out or blocks any calls to everything deemed an ad. advertisers constantly update so the lists constantly update but buying a domain is more expensive so ad blockers have the slight advantage.",
"Almost no sites sell advertising space themselves. It would but far to expensive to maintain all the infrastructure. Instead they have a deal with big companies (Facebook and Google are the biggest ones) that they'll give them a space on their sites and they can play whatever they want. Like a billboard. Now, as they are all coming from these networks it's easy for a program to spot ads. They simply have to look at the code, see the part that basically reads like \"download this part from the Google Ads server when the site is clicked\" and block that out."
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dnrz2p | What is a rootkit? How does it work? And what does it do? | Technology | explainlikeimfive | {
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"Software on a computer comes in layers. All of the layers are build on top of eachother and the rootkit gets installed in one of the lowest levels. This makes it harder for security systems to detect them because they're running in higher layer's. Because the rootkit is installed in such a fundamental level it's able to manipulate higher functions to do what the programmer has set out to do. Maybe it only to introduce a weakness in other programs or will give some control over your computer power. For example they can turn your computer into a node that just sends simple packages to an address. Get enough of those and you can drown a system in requests making it vulnerable to attack or taking it offline."
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dns0is | Why car computers are so slow? | Technology | explainlikeimfive | {
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"They are different systems. The airbag system for instance is super fast (quicker than you can blink) whilst the radio or satnav doesn't have to. You also may encounter a problem with heat dissipation on some elements (and this is why you don't have the fastest processor on your radio). The infotainment system will also slow down over time as (just like any computer) will accumulate crap over the years",
"The car doesn't have one computer, it has many small computers. The system that operates your touch screen isn't controlling the engine or anything like that. There are some intentional decisions to use slower but more reliable computers in environments that may be excessively hot or cold or where reliability really matters. Your regular home PC is meant to operate with a room temperature generally between 0 and 40 degrees Celcius (about 32 to 104 F). Your car on the other hand will be started up in the dead of winter or after it's cooked out in the sun in summer and expected to just work. Getting something to work reliably in these environments and have a really fast CPU speed is difficult. Still, what you're describing sounds a bit extreme."
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dnsgv0 | how does 2 factor authentication work? | Technology | explainlikeimfive | {
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"You verify one way, then you verify another. Like an email gives you a code, then you get a code sent to your phone thru text",
"You can identify people through \"something you know\" - a password/PIN, \"something you have\" - a phone to receive messages or an authenticator, or \"something you are\" - biometrics like a fingerprint or eye scan. 2FA just demands two of them from different categories."
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dnue0l | Why can't a DSLR camera record in 4k if they can take pictures with a resolution higher than 4k? | Technology | explainlikeimfive | {
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"To recorded video you need to capture a picture at the frame rate you film at. So for 30 fps video you need a sensor that can read out a 4k image from the sensor 30 times per second but to take a still image you do not need that. A optical senors capture light in small \"buckets\" that convert it to electrical charge that you need to count ie convert to a digitale values. This take time to converts. To do that faster require more complex electronics to be able to do that at the speed needed to capture a video. So to read out the image from the senor take time and for still images it might longer then time needed for video. There is also another limitation and that is the CPU and storage system of the camera. The need to be fast enough to handle the data from the senor. You need more performance t to capture video then still images at a lower rate so that can be the limiting factor.",
"Just because it can take a picture at a resolution higher than 4k doesn't mean it can do so 30+ times per second. The tech needed to do so does exist but the camera makers opted not to do it.",
"There are cameras that can do this, but it requires expensive processing circuitry. Most DSLR makers see a larger markets for cameras without this capability."
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dnutg5 | How does pitch correction/autotune actually work? Likewise with voice changers | Technology | explainlikeimfive | {
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"Your voice is composed of a whole bunch of frequencies. Modern computers can record your voice, do a bunch of math to find these frequencies at any given instant, shift them all, and then generate new sound using these shifted frequencies. They can do this so fast that it seems seamless."
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dnx06p | How does the internet exist? No I'm not talking about us using it but more so, what's actually causing it to run and who's in charge, who could possibly end it? | Edit * WOW 700 VIEWS, THANKS SO MUCH.. PS. I didn't know I could write in this box! | Technology | explainlikeimfive | {
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"The Internet is what we call a global data network consisting of many sub networks belonging to various companies and governments. It's kind of like asking who owns the road? What road? The world is connected with roads, some going from one country to another, and in many cases many countries. They connect places and people, and allow us to visit businesses and others. The way you know where to go is by looking up the address of a location (DNS, see \\[1\\]) and then checking a map to know how you get there (routing tables, see \\[2\\]). Addresses are also governed by an entity which hands them out, and once they've been handed out, have an easier time being subdivided to other companies and institutions, or even individuals. The important part left is then who creates the map (see \\[3\\]) because this changes constantly and determines the path we take to reach our destination. & #x200B; \\[1\\] For example when you type in an address in your browser, your computer sends a DNS request to the DNS server that it has stored in its settings, which responds to your computer with an IP address, and your computer then can send data directly to that IP address. The DNS network however does have some governance in the sense that there are root servers at the very top level, but there is no requirement for the requests to reach them as they can be manipulated by a DNS server at any point in the chain, although in most public cases isn't needed or done. \\[2\\] Mostly in this case we talk about globally routed addresses. For example, your computer needs to really only know where to, within its own network, send data if it's outside its own network, it doesn't need to know anything more than that. This local destination is called your gateway and in most residential setups is handled by your router. So your computer wants to reach an address on the Internet using a domain (something dot something), gets an IP from the DNS server, sees that the IP (say 216.58.211.142) is not within your own network (say 192.168.0.0/24) so it sends the data to its gateway (say 192.168.0.1, which in this example is your router). Your gateway has a routing table just like that (\"This is my local network, anything outside of it, send here \\[another IP address\\]\", called a default route). As you go higher up the chain from your home, into your ISPs network, and then beyond, the routing table will increase until we find a routing table that describes where we can find the location of the IP address you are looking for, and then start to decrease as the packets hit those routers since we are getting closer to the target the devices hit need to know fewer and fewer routes. \\[3\\] Throughout the Internet are the above mentioned routers. They belong to companies, institutions, governments, and some individuals. The point is, these routers communicate with each other. They most often on the Internet use a protocol called BGP. In this protocol we determine with whom we'd like to talk, and what we'd like to say. The things the routers exchange during these talks between themselves are routes, so that each router knows what the router it is connected to is itself connected to. This is why the higher up we get, the routing table grows, so that we at the highest point know where to send data no matter what the address is (I am router A, and I want to send data to IP X, looking at my routing table the router that knows where that address is goes via router B, so I'll send my data there and then it is router B's problem). & #x200B; Put very simply and omitting quite a bit, this collection of roads, addresses, and maps is what we call the Internet. There isn't a single point one can attack bring it all down, and there isn't one entity controlling everything, but if someone was dedicated and had the resources, they could disrupt parts of the Internet for a finite time. & #x200B; I apologise if parts of the above seemed rushed, I'm finishing this with 2% battery left. I'll check comments later if I've left anything unclear. & #x200B; Edit: I tried to simplify the basic idea, but for the folks wondering what 5 year old would understand this, ELI5 isn't for actual 5-year-olds (rule #4).",
"The internet isn't one thing that someone could just shut down or with someone in charge off. It's a network so basically it's just computers connected with each other. Some of those computer are just laptop or destop they are for user like any normal computer you ever used, while other computer are use as servers they are specialized to just have a bunch of website page on them with a directory to make it easier to find those webpages. So when you type an address that the addresse of the page on a servers, your computer send a signal through the network to that server to send you the webpage. Nobody is in charge, there is several communication companies that own cables through the world, some go underwater to connect different continents. So for example Google own 63 thousands miles of submarine cables which is 8.5% of the world total, so if Google wanted to shutdown their stuff it would take time to remove to disconnect all of their cables, and maybe some region would end up with bad connection, because now the information need to pass through longer or older cable, some region wouldn't have any internet anymore, think small Island with only a couple of cable to connect them, but most people wouldn't see any differences depending where you live. You would have to cut most of the cables submarine or onland to disconnect everboby from the internet.",
"Imagine if there were only three computers in the US, located in San Francisco, Kansas City, and New York City. The SF computer is connected by cable to KC, and KC is connected by cable to NYC. So far, that means SF and NYC can talk to KC. What makes these computers special is that they advertise that they are willing to help you talk to other computers. Specifically, the KC computer knows it's connected to SF and NYC, and says that it's willing to ferry messages on their behalf. This means that SF can now talk to NYC, so any computer in this network can talk to any other one. Here's where it gets interesting. If Los Angeles buys a computer and wants to get on to the network, all it has to do is connect to SF, which is the nearest one. Because the SF computer (just like the KC computer previously) knows how to route messages for other computers, it means that the LA computer can talk to KC and NYC as well. Now, let's say Austin wants to join in the fun, and connects to KC. But now the LA-Austin connection has to go through SF and KC, which is slower than we'd like. At great expense, we can directly connect LA to Austin by cable for better performance. This is really cool, because any LA-KC traffic can now either go through SF or Austin, *depending on which one is faster*. In fact, SF can break down entirely, and the rest of the network can still route around the failure. (On the flip side, a country like China that wants to control information would do the opposite, by deliberately funneling all traffic through a specific set of computers that it controls, so that it can selectively censor certain messages by simply not ferrying them across.) So as you can see, there's nobody specifically in charge of the Internet. There are standards committees that decide how these computers can talk to each other, but as long as you connect to somebody who is already on the Internet, you're also on the Internet. You connect to an ISP, who in turn connects you to the rest of the Internet. Reddit also does the same on its end. Then numerous computers (now specialized computers called \"routers\" that do nothing but ferry messages for a fee) in between gets your request to Reddit and brings back a web page for your computer to draw.",
"next question: how can i be an internet provider? i mean, i don't want to rent other company internet, i want to \"create\" my own internet (that is connected with the normal one)",
"The internet is a network of networks connecting many computers together. Physically, it's a bunch of fiber optic cables running over most of the planet, including under the oceans, to connect the different continents. The company that owns the cable also owns the hardware on either end of the cable. That company lets other companies connect to their cable for a fee. The cables that run under the ocean, and across vast distances on land are called \"backbone\" cables, as they function sort of like your spine. It's a big bundle of cable that branches off in many places to connect remote locations to a central network. The backbone cables are owned by companies, and those companies allow other companies to connect. Some companies own a different section of backbone, and some are small internet service providers who act as an intermediary between you the consumer, and the company who owns the nearest backbone segment. All these different segments of the network are owned by different companies, but through mutual agreement they're all interconnected, which is what allows the internet to exist as it does. On a logical level, the internet is just your computer talking to another computer, or a series of them. When you navigate to URL_0 , your computer asks a domain name server for Google's address. Then your computer connects to that address, and downloads whatever data the server wants to send you. Physically, your connection is routed through many switches and miles of cable, but the core point is that it's simply a direct connection between your computer and the server. And that's how the internet works. No one person is in charge, and that's a good thing. If one or two companies shut down their backbone service, we'd see large slowdowns, and some outages, but for the most part the internet would continue to exist. It's a very robust system, full of redundancies."
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dny0te | If you have a sound box that plays at 50% volume and you put another (same exact) box next to it and play it at 50% volume. Will the sound be twice as loud or stay the same because they are both playing at the same volume ? | Technology | explainlikeimfive | {
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"Depends where you're standing. [Check out this picture.]( URL_0 ) There's dark lines - if you're standing there, the sound will be much quieter. In the regions with stripes, the sound will be louder. The sound waves interfere with each other. A sound wave is a series of contractions and expansions travelling through the air. If the contraction from both speakers lines up, you get a really strong contraction, and if the expansion from both lines up, you get a really strong expansion. That makes the volume louder. If the expansion from one speaker lines up with the contraction from the other speaker, they cancel out and the sound gets quieter.",
"It may be 3dB (twice the power), or 6dB (twice the amplitude= 4 times the power) louder. Yes it's louder, but not that much. Decibels are not very intuitive when you're new to them."
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dny1m6 | How do inhalers work? | Technology | explainlikeimfive | {
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"The medication delivered by the inhaler is a bronchodilator that relaxes the muscles of the airways into the lungs, making it almost instantly easier to breathe and for the lungs to work more efficiently Edit: informative link- URL_0"
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dnyhqs | How does one yellow RCA cable carry video? | RCA cables only seem to have one pin each. How can one cable carry color video, but stereo audio requires two whole cables? It doesn’t seem like the amount of data is comparable. | Technology | explainlikeimfive | {
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"A RCA cable have two wires not just one. One is connects to the inne pin and the other to the outer ring. For all electrics connector you need two conductor. Often the like the 3.5 mm audio connector with 3 wires you have on common ground and a conductor for each audio channel. The number of wire do not directly determine the amount of data it can carry. Look at the cable you use for Cable TV or over the air TV with two conductor but you can have multiple TV channels with sound and video.The amount of data depend more how you encode the data in the conductor. So it is a trade off between complexity of electronic in a device versus number of conductors. Stereo sound uses two pairs because you can then have very simple signals. You can have stereo sound in one pair if you add some electronic to encode it some way that you can later separate them. But if you use two wires you can have signal in the form you get them from a microphone and can drive a speaker or head phones directly after just amplifying it without any complex electronic conversion. So two conductor pars is a cheap way to do stereo sound. The standard is not from TV but from audio equipment where you just have sound in two part and video copied that. One reason is so you could use audio amplifier you own for better sound the a TV can provide. For video the signal you have is complex signal and you have complex electronics in the TV that can convert it into separate red, green and blue signal that is used to control the the screen. The signal is identical to how a a TV channel it transmitted analog over the air or in a cable TV network but is moved from a high frequency to low base frequency. So the complex electronics to split the signal apart exited in all TV. So the simplest way to transfer a video signal was in a format at TV could decode. The composite signal is how the over the air signal is after it is demodulated by the tuner in the TV. So to add a composite in just add a connector on the outside and something that can change the input from the tuner to the outside plug. The tuned have separate output for video and audio so there is not simple way to use only on one wire with converting it to a high frequency radio signal. To convert the signal will require stuff that cost more the two extra wires so you avoid it if you can But it was way to get a VCR or game console into a TV before composite and SCART become standard and then you had sound and image in one wire pair. There is other way it have been done and in Europe you hade the more complex SCART connector with more wires. It transmitted data split into a red, green and blue and a sync signal and had the stereo sound in a single quire large 21 pins connector. The quality of the signal was a lot better and old computer that could use it as a output resulted in superior image quality the a single composite cable that was common in the US. The signal is quite close to how a analog VGA video output from a computer work, the image part is identical but SCART have difference sync. You could get some graphic card to output a SCART compatible signal. So is is not the case that stereo require two pair because cable TV deliver multiple video and stereo audio channels in a singe pair. It is the case that you need less stuff to use to pars. The video is a more complex signal and you can split up version is 4 paris like in SCART. So it is a trade off between complex electronics vs more conductors.",
"I could be wrong, but I believe audio *can* be carried on one cable, but the point of having two cables is to plug one into each stereo speaker and transmit surround sound. One cable carries the left side of the sound, and one cable carries the right.",
"I don't think it is a matter of how much data is passing through them. They are left and right cables so each can be plugged into a left and right speaker.",
"Lot's of responses so far, but none quite answer you right, IMHO. You're right, the amount of data is not comparable. To start, data today is carried on most wires by super fast complex sequences of low and high signals that we call digital signals. This includes HDMI cables, cable tv line, Ethernet, and USB. This is why any kind of audio/video/other data can be carried on a single cable, even cable tv line with one conductor and ground. The wires you're talking about are analog, but very similar to that cable tv line which is a conductor and a ground. Analog means that the shared interpretation of the audio/video is between 0 and a configured high voltage level. Your question has to do with how the audio/video signal is carried (encoded) on the wires. Encoding means a shared way of communicating data that both the device sending the data and the device receiving the data understand. Most RCA audio (the red and white colored jacks) is pre-amplified audio, but uses the same signal that you could plug into speakers and hear (faintly) audio from. This is an analog non-encoded non-compressed signal, where a speakers elements will move at a certain rate based on the input signal, and you'll be able to hear the output. If you could magically \"hear\" what's on those red and white cables, it would sound the same as what comes out of the speakers! The yellow cable on the other hand uses a complex analog signal encoding that was developed in the 1950's. That signal carries information such as color, how light/dark, hue & saturation levels and a way to synchronize how often that changes. Simple? Not really. Cool? Yes. Sometimes you'll find the yellow jacked cable to be thicker than the red and the white jacked cables. That's because shielding/signal integrity is more important since it's a more complex signal.",
"A cable can carry any amount of information so long as you serialise it (that is, put it in a string of instructions one after the other - red, green, blue, next pixel, red, green, blue, next pixel, etc...). RCA is called composite video - it's actually a mishmash of red, green and blue values combined with values for \"end of line\" and \"end of screen\", all lined up one after another. If you made it faster you can shove even more stuff in there, if you like. But composite/RCA tends to mirror how old TVs were made and operated so a composite signal be split into syncs and colours signals and could directly drive the TV. So long as you can transmit those signals fast enough and over a cable good enough that the other end can reassemble them as they are needed, they do the job. Say, 60fps of 640x480 8-bit RGB signal, for instance. Wanna blow your mind? The cable that is plugged into the TV aerial is doing that over thousands of frequencies simultaneously, just the same, and we've been doing that for decades before computers in people's homes were a thing. RCA composite only has one \"channel\". And an aerial has also got sound queued up in its datastream too, and teletext, and all sorts. A composite signal is what you get if you isolate only one frequency from an aerial from an old analogue broadcast aerial. The amount of data you can put down a cable has almost nothing to do with how many pins, but how fast the carrier oscillates and you can serialise the data onto it. In the same way, hard drives used to have direct pins, then went to lots of parallel cables, then to one (fast) serial stream, then to multiple serial streams over parallel pins. RCA is three pins for convenience of wiring (speaker on the left with one cable, TV in the middle with another cable, speaker on the right with another cable). SCART (Euroconnector) was a predecessor to things like HDMI long before digital TV signals, and it can transport 20-something different types of information (colour in RGB / YUV / audio / data / control / etc. all over one cable with 20-something pins). The average VGA/DVI/HDMI cable has less pins and more information (because it serialises the data over the pins faster). One cable can carry whatever you want. USB only has (had?) two data cables inside it, and you can do DVI etc. over USB if you want, as well as Ethernet (4 data pairs), etc. It all depends how fast you change the information on it, and how much information you want to cram into that ordered list of instructions. When you use more than one cable it's usually for a different reason to not being able to carry that data on just one wire - that you want to simplify hardware design (so you don't have to multiplex the information for different earphones, for example, onto only one cable), that you don't want it interfering, that you want the hardware at the other end to just get one type of signal only (e.g. you don't want the right earphone to have to care about information for the left earphone), or that you can't oscillate one cable fast enough to get everything you want down it without making the hardware incredibly expensive (e.g. HDMI, Ethernet, etc.). It's cheaper to make, interpret and read 8 different 10MHz signals than one 80MHz signal, for example. This is the basis of PCIe \"lanes\", USB, Ethernet, HDMI cables, etc. everything. RCA cables, by comparison, are positively antique. The number of cables has almost no bearing on the data signalling rate used, but more often practical design considerations. In the old days, 10Base2 was a networking technology based on a single data wire and hit 10Mbps (far more than a TV channel). Ethernet can get to 40Gbps on 4-pairs over 100m, but HDMI has 29 pins and can only do 48Gbps in the very newest versions and only gets a few metres long before it stops working properly. SATA has 4 data pins and does 6Gbps. IDE used to have 40 pins and barely hit 133Mbytes/s after decades of advancement. TL;DR: If one lane on a motorway runs at 100mph, it's going to get more traffic moving through it than an 8-lane motorway with a 10mph limit. RCA is a 1 lane-motorway for video, which means that the different colours, etc. have to sit one behind another in an orderly queue. There's another lane for \"left speaker\" and another lane for \"right speaker\". But there myriad other technologies with less lanes, more lanes, and greater and lower speed limits, and where the information doesn't have to go down particular lanes, or where it all gets thrown on the same lane. The number of lanes isn't really a design feature for maximising throughput. It's a feature to direct traffic to the right place so that Audio Highway only ever deals with Audio information, but there's nothing stopping you lumping it all together on one lane and sorting it out the other end."
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dnywey | How is a qubit in a quantum computer physically represented? | I understand that in traditional computing, a bit is either 0 or 1, where the physical representation is zero voltage for 0, and positive voltage for 1. From my limited research of quantum computing, it's saying that a qubit can be 0 and 1 at the same time (in a "superposition"), but how does that translate to electronics and electricity if voltage can only be one or the other at any given time? | Technology | explainlikeimfive | {
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"Well, first off, voltage actually *can* be analog. It is simply less efficient to do that. You can have 1 volt, 2 volts, or 1.26947298 volts. In quantum computers, the quibit is stored in a quantum state of a particle. I'll use photons as an example because I actually understand them: Photons can be polarized. Their polarity is basically a direction. If we choose two directions and say they represent 1 and 0, then anything between these two is a little bit of both. If it is closer to 1, then it is a higher percentage 1. The bit is represented by the polarity of the photon.",
"Qubits are two-state quantum systems. That means they are systems that can be subject to the laws of quantum physics, but at the end of the experiment can only end up in one of two states. There are several different types of qubit, like superconducting loops, ions, and light. The common quality of all of these things is that they can be held in quantum states states that we can read and manipulate. The way in which they store information has no classical analogue. That’s part of what makes it so powerful. The information isn’t held or processed by transistors or anything that normal computers use, so don’t think in terms of voltages or that sort of stuff. Rather, a qubit is put in a state that holds information about how much 0-ness and how much 1-ness it has. It doesn’t matter what the qubit is actually made of, it’s the state that has the important information. The role of the qubit is to hold that state in reality and interact with other qubits while we control and eventually observe them. The way in which the states interact drives the qubits towards being more 0 or more 1. Ultimately, information that you eventually get (0 or 1) is read off via classical means, the exact method of which will differ depending on the type of qubit (for some types it will end up being a current measurement), but the information processing during the computation is due to the interacting states of the qubits, and while that’s going on we have no access to that information *nor is it being held in a way that we can ever observe*. This is quantum information being manipulated by quantum interactions, so don’t try to think of it in terms of transistors or voltages. It’s a wholly quantum world. We can’t think in terms of quantum physics other than in a mathematical sense, so if it seems weird then that means you’re actually thinking about it. If you want an ELI10 then [here]( URL_0 ) is a comic by one of the geniuses in the field."
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dnzifh | How do games like Fortnite, CS:GO and LoL ensure that the user isn't using a hacked/modded client? | Technology | explainlikeimfive | {
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"Technically they don't, which is why they continually ban players for cheating. So a better question is, \"How do you detect cheaters?\" There's a lot of third party software used to detect cheaters. Some are very basic, while others are complicated. One way is to check for impposible things. Let's say your game only allows a player to move up to 1 meter per second, no faster. If a player moves faster than this then they are cheating. But what if there's a bug that sends a player flying faster than 1 meter per second? Then that player will be marked as a cheater even though they did not cheat. Innocent players being marked as cheaters and banned happens quite a bit. Because developers believe they are infallible they refuse to admit there could be a problem with their cheat detection. Guild Wars 2 caught innocent players in a ban because it marked empty files as files used for cheating. It wasn't until a player used the European GDPR law to get their data that they found this out. Arenanet refused to admit there could possibly be a mistake. Another way is heuristics. The anti-cheat software looks at the way you play to determine if you're cheating or not. If you get hundreds of headsets without aiming and without missing it might mark you as a cheater. But what if you actually are that good? I refer you back to the part about innocent players being marked as a cheater. Some anti-cheat software will scan for cheat software that's running. The anti-cheat software has a list of cheat software. It doesn't check if the software is interacting with the games, just that it is running (or exists in disk even if it's not running), and marks the player as a cheater. This is a terrible way to check for cheaters because a lot of \"cheat\" software is used for other purposes, or not for the game. If you have Cheat Engine installed you might use it for a single player game, and never a multiplayer game, bit the anti-cheat software won't care. If you're a software developer you'll have tools to profile your software, which anti-cheat software might see as tools for cheating."
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do18pt | Why do most phones require a PIN on startup even when a fingerprint or other unlock method is normally used? | Technology | explainlikeimfive | {
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"Because you need the PIN or passcode to decrypt the phone's \"hard drive\" where the more sensitive user data is stored (as opposed to the operating system). Once the PIN or passcode is entered, the phone is decrypted and can default to a less secure face/fingerprint unlock, because the decryption key is stored in RAM (which is purged when the phone is turned off or restarts). Similar reason to why changing your PIN or passcode requires typing in the old one first.",
"It's been proven that the finger print scanners on phones for the most part aren't that secure. They can be easily fooled by a determined individual and a pin is actually more secure. So it's required on startup first (also again after so much time has passed and then you can start using the less secure but far more convenient fingerprint method. Otherwise someone could bypass the finger print security and have unlimited access to your device.",
"Your PIN/password/passphrase is used to encrypt the device. This means that the mathematical key to turn the phone's storage from complete nonsense into actual data is derived from your password. Part of what's stored there is information about your fingerprint/irises/face/voice to enable unlocking later. For devices running iOS, upon the first unlock, the mathematical keys are further encrypted with keys belonging to TouchID/FaceID, and then those systems \"hold onto\" those keys, until you authenticate to them with your fingerprint or face. Upon certain events happening, those keys are destroyed, meaning that your PIN/passphrase is needed to unlock the device. According to the [iOS security manual]( URL_0 ), they are: •The device has just been turned on or restarted. •The device hasn’t been unlocked for more than 48 hours. •The passcode hasn’t been used to unlock the device in the last 156 hours (six and a half days) and a biometric hasn’t unlocked the device in the last 4 hours. •The device has received a remote lock command. •After five unsuccessful biometric match attempts. •After initiating power off/Emergency SOS. The other answer I see here is... shockingly incorrect, which is particularly dangerous when we're on the subject of personal device security."
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do1q0s | I'm trying to download Modern Warfare but it's only downloading at 30mb/s when the test I do says my download speed is 300mb/s? | Technology | explainlikeimfive | {
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"Your speed is only one factor. The upload rate of the server you are downloading from also matters. There is only so much bandwidth-- if many people are downloading it at the same time and the server is near its bandwidth limit, it'll divide it up among the people downloading. That's probably the server limiting its upload speed for everyone to 30mbps, so no matter how fast your speed is it can't download faster than the server is giving it data."
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do3eni | how did we get from the Wright Brothers to operational aircraft for war/transport in less than 15 years, then a moon landing 50 years later? This pace of technological innovation seems insane. | Technology | explainlikeimfive | {
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"War is an amazing motivator for innovation. WW1 for planes. WW2 for rockets and also planes some more. Cold War/space race was for more rockets as that would determine who would survive in either a nuclear war or who would win the space race.",
"What you're seeing is the build up to the technological singularity. Basically, it works like this: The better your technology, the quicker you discover new technology. So, we're building up speed. We spent the first few thousand years of our existence discovering basics like agriculture, masonry and metal working. But, as our tech improves, the next discovery happens sooner and the one after that is even sooner. The singularity is when we reach a point where new discoveries will occur every year, every month, every week. No one really knows what that'll be like, but we'll be making discoveries so fast that we'll literally be leapfrogging technological advances to try and stay up to date. It's kinda scary when you think about it, but man, what a time to be alive.",
"Prior to the wright brothers' flight, we had spent thousands of years doing creative things with new ideas. Applying the new technology of flight, as well as all sorts of other forms of technological advancement, combined with all of the math we've been coming up with for thousands of years, allowed us to do some crazy shit with new technologies.",
"combo of science breakthroughs (QM et al) and the need/drive to push/explore to be the first, i.e cold war RE: the moon missions. And then of course, once some principles are known, people push and push to exploit to make money. the last 100 or so yrs has been utterly crazy in terms of technological advance. from morse code to decent internet on a phone. wtf. again, science breakthroughs and the need to drive it further, at first it was the cold war, now it's money. funny thing is, the scientists who work this shit out are usually PHD guys/gals, doing the work for their certificate/qualification, on a very very low pay if at all. At best a name check on a journal entry on their 3-4 yrs work. unless of course einstein etc who just blew everything out the water."
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do4zvt | What is trickle charging and how does it improve the battery life of a battery? | Technology | explainlikeimfive | {
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"You can fast charge a lithium battery to 80%, and then you have to slow the charge rate down or you'll damage the battery. Here's a simple analogy: If you're trying to fill a glass with orange juice right to the top, you don't pour it in at full speed until it's full like [some crazy person]( URL_0 ). As the glass gets full, [you pour slower]( URL_1 ) and let the juice *trickle* in until the glass is full. Except instead of orange juice, pretend it's electrons, and instead of a mess that can be cleaned up with a paper towel, it's a mess that needs to be cleaned by the fire department and skin grafts. Edit: typo",
"Trickle charging used to mean charging a lead acid, NiCd or NiMH cell at a rate that is less than the rate which the cell can dissipate when overcharged. Gasses are created, which migrate across the cell and are re-absorbed. This wasn't that good for the cells, but it was OK. With lithium cells, however, you can't do this. A lithium cell will keep charging until it generates elemental lithium, which will then catch fire. So for them, trickle charging just means charging at a low rate, over a long time. Say, charging at 0.1C over 10 hours. It is better for the battery because it creates less heat, so the cell remains cool while charging, which means less side reactions happen. Side reactions bind up the lithium or other chemicals so they don't break down when discharged so no longer work to store charge. But you still need circuitry to determine when the cell is full and stop charging."
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do74p0 | Why are the letters on the QWERTY keyboard positioned this way and how come the Dvorak keyboard was never adopted despite its efficiency? | Technology | explainlikeimfive | {
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"As far as I know, originally the letters were organised like they are because typewriters tended to get stuck if the letters that were pressed were next to each other. Thus they organised the letters so that the most used letters were next to least used ones so they'd have the least chance of getting stuck. That way the typing would be most efficient. The order of the letters stayed even when the problem went away along with computer keyboards, because the order was already familiar so they decided it would be easier just to keep it the way it is. Correct me if I'm wrong!",
"I should mention that the studies which \"proved\" Dvorak was better were funded by Dvorak himself. QWERTY actually does a pretty good job of alternating letters back and forth between the left and right hand. As a result, an experienced typist on QWERTY is actually pretty close to what their optimal speed would be on a better keyboard layout (assuming we're talking about flat keyboards and not weird hyper-ergonomic typing orbs.) Colemak and Maltron are probably also marginally better than QWERTY in the same way Dvorak is supposed to be.",
"Before people used computers and printers, they typed things up on typewriters. These were mechanical contraptiins, and used arms with the letter on to type thay letter onto the paper. Now, you could have all letters in alphabetical order, and call it a day. But then some issues arise. The big one being that if you typed too fast, the arms got tangled. So that's why they changed the layout to QWERTY. It's got a good layout to avoid tangling the arms, while still being able to type at a decent speed. I can't say for certain why DVORAK isn't being adopted widely, but my guess is that people just aren't used to using it. And so it woyld require getting to grips with a new way of touch typing.",
"Because the qwerty keyboard was adopted due to it being the primary layout on typewriters before the advent of the computer. It was what was familiar and used by an extreme majority of most people who would be using them. Qwerty came about in the first place because it was used to slow people down while they typed so that the mechanics of typewriters wouldn't bind up or eat the ink tape. Dvorak is much faster once learned, but qwerty is so engrained in everyone's everyday life that it's become the standard for much of the world. You are still able to order and purchase dvorak keyboards if you would like though."
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do7rua | How braces work and move teeth. | Technology | explainlikeimfive | {
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"To be very short and simple - they get glued to the teeth and therefore slowly move them into intended place. That's why you need to visit your doctor regularly to keep everything in check and to adjust your braces accordingly"
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do8jz3 | How does an electric guitar produce sound? | An acoustic guitar has the empty part to have the sound waves resonate like any other instrument, but an electric guitar doesn’t. How does it produce sound from just the strings? | Technology | explainlikeimfive | {
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"The strings is generating the sound in both electric and acoustic guitars. However in the acoustic guitar the sound is amplified by the resonant cavity which provides an impedance match that helps the energy from the strings be transmitted as sound waves. Whereas in electric guitars there is a pickup that converts the movements of the string to electric signals that gets amplified in a guitar amplifier. So the difference is not in how the sound is generated but in how it is processed and amplified.",
"Other answers pretty much sum it up but I figured I could go into more detail, the strings of an electric guitar resonate over a pickup which is a unit comprised of magnetic poles and copper windings, when the strings move they generate an electric current in the pickup which comes out of the guitar and runs into an amplifier, in a tube amplifier the signal will hit the preamp tubes which are responsible for shaping the tone, if you over drive the tubes a distortion is produced that we find pleasing, while in the preamp stage eq can also be applied to further shape the signal before it hits the power amplifier which is the set of tubes that boosts the signal from line level to speaker level, then the signal goes out to the speaker cab, there are also solid state amps the will have a similar signal flow except using transistors instead of vacuum tubes. There are a variety of different pickup designs using two sets of magnets wound in reverse of each other makes a hum bucker pickup which cancels out the 60 cycle hum single coil pickups are susceptible to at the cost of some clarity and dynamics, there is also a type of pickup called a piezo pickup which is often found on acoustic electrics which uses crystals under the saddles of the strings that generate a weak signal that is then boosted by a preamp in the guitar, this is why acoustic electrics require a battery where passive electric guitars do not",
"There are a couple of things in physics, specifically in electromagnetism, that need to be understood before the working of an electric guitar can be well understood. 1) an electrical current going through a wire will produce a magnetic field 2) this can be exploited by wrapping coils of wire around to amplify the magnetic field, in a device commonly known as an electromagnet. 3) Unlike a static magnet which has a set north and south pole, the polarity of the electromagnet changes with the frequency of the electrical signal (in hertz, or oscillations per second). (and as a bonus, I don't know why that's a property of an electrical charge, but it is) 4) All of this works in reverse; so if you wrap a coil of wire around static magnets and then disrupt that magnetic signal with ferrous metals, it will produce some electrical signals. So, 4 is what is really important to our tech here: an electric guitar creates sounds through the use of what are called electric pickups; these are poles of metal (generally steel) that are attached to a magnet (thus making them magnetized) with coils of copper wire wrapped around them. The guitar strings used on an electric guitar are almost always some form of steel, though occasionally a nickel alloy is used, and the strings rest above the poles of the pickup. When the strings vibrate, they do so at a certain frequency, which then creates an electrical current through the wires coming out of the pickup; these are connected to the output jack of the guitar, and the current generated is extremely small. The output jack of the guitar gets plugged into an instrument cable which feeds into an amplifier, which works to take the signal it receives through the input and pumps it with more power, but keeps the frequency of the initial signal. When dealing with waves that get converted to sound, frequency converts to pitch (higher frequency being higher pitch) and amplitude converts to volume (higher amplitude being higher volume), so keeping the pitch/frequency is important (unless you're altering the signal with an effects pedal, but that is a bit beyond the scope of this ELI5); this boosted electrical signal gets sent to a speaker, which works in the opposite manner of a pickup; the speaker has a coil of wire directly across from a static magnet, with either the static or electromagnet (I forget which every time I think about amps or speakers) attached to a relatively thin membrane that can be moved by the magnetic fields generated, at a frequency equal to that of the current's frequency. This membrane moving then pushes air in that exact pattern, which creates pressure waves that hit your ear drum and are processed by your brain as sound."
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do97b3 | what does “packet loss” on an online game mean? | Technology | explainlikeimfive | {
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"Think of a mail main, your device sends packets. It's small bits of information transmitted to and from your device. Every request for website, game or app that's accessed the internet sends and receives data in packets. If you have packet loss then let's say your device sent 10 packets to your provider. But only 8 of the 10 was recieved. So 2 of them was lost, your provider sends back a notification and your device resends them. This happens regularly but to much will lead to lag in games, slow website loads or just unable to access what your trying. Causes could be congestion on the site your trying to access, bad connection with your isp, all the way to bad modem or one of the cables on your end. Also could be inference on your wifi with neighbors wifi, if they close to same channel. Lots of things can cause but in short, some of your data isnt reaching its destination so its having to take longer to resend it.",
"Think of it like getting interference when you're trying to have a phone call. If the person on the other end is trying to explain something to you buy they keep cutting in and out because of bad cell service, you're going to have to keep asking them to repeat themselves. This winds up slowing down the conversation a bunch. So imagine the game is having the same problem; when you click a key to jump or something, if there is packet loss it may take a lot longer for the game server to receive the command to make your character jump and you might die because you fell instead of jumping."
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docd8j | Why is sending images on messaging platforms like discord considerably slower than video call, where you're sending each other over 30 images per second almost instantaneously? | Technology | explainlikeimfive | {
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"**Sending an image** is a kind of file transfer. It uses a TCP (Transmission Control Protocol), which is connection oriented. Essentially, all hosts (i.e. both you and your friend's computer, or each computer and a server in discord's case) care about what is being transferred and if it was done so correctly. It does this by sending both the image itself and a 'hash'. The hash is just the image data sent through a particular algorithm resulting in a string of what appears to be gibberish. However, the receiving computer can run the payload (the image you sent) through that same algorithm and compare the hashes. If they match, the image was sent completely without error. If not, the whole thing must be sent again. **Video Streaming** typically uses some connection*less* protocol (like UDP). In this kind of interaction, both hosts don't care what is being sent or if anything is lost. If some packet doesn't make it or is damaged, it just moves on to the next like there isn't an issue. This is considerably faster but you will inevitably end up with packet loss (and stuttering/blurriness) unless the connection is perfect.",
"During a video call you can use compression very effectively because only a few pixels change from one frame to the next. Basically you're not sending 30 full images per second, but just the changes between frames. The quality requirements are also much lower compared to a photo that you're sending. Secondly, the connection has already been established, so it's just streaming data. If you send a single photo, your browser has to establish a new connection to the server to upload the image, and when that has finished, the client needs to establish a new connection to download the image, and there are delays associated with that.",
"So many incorrect answers here... So, assuming the same quality of picture (but live video calls are often sent at far lower resolution which makes for exponentially smaller sizes); If you send a picture, barring some still-image compression that gets the thing down from (say) 10Mb to 1Mb, you send the *complete picture in full detail*. If you send another picture, that is a completely different thing and that whole picture is also sent *in full detail*. With video, you send a key frame (full picture) and then video compression sends only the differences from one picture to the next, which reduces the amount of information hugely. A new key-frame may be sent every few seconds, or key fragments may be sent as a rolling-update sort of deal. There are other factors too, platform dependant, which may or may not apply; * Live video/audio traffic may (very likely) be prioritised over text or static pictures because it doesn't matter if a picture or text arrives 5 seconds late, but even half a second late for a video or audio frame is useless. * Video/audio may be captured at low resolution / bitrate compared to the full quality of a static picture. * The frame rate may also be low, you assume 30fps but with a bit of cunning you can make 15fps look quite acceptable, that's half the data rate right there. You'd be amazed what even H.264 can do with 1080p30 video, it can get it down to 64k/sec (nominal bandwidth of a normal landline voice call) - so knock that video call down to 720p and 15 fps and you knock \\~75% load off (or get 75% better video), with more modern encoders tuned for the task at hand (EG knowing it'll be a talking head and static background) you'd be amazed at how good that could look over a 64k link."
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dogsn8 | How is it possible for a smartphone to say how much the battery or phone is loaded? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"It doesn't actually know how much charge is left in the battery. As a battery charge depletes, the voltage level drops in a predictable manner due to the battery chemistry. They determine this voltage curve through hundreds of tests and attribute a voltage to a percentage, then program that voltage curve to each phone. The phone measures the battery voltage and plots it on the curve to determine a percentage. A new battery has a more gradual decrease in voltage. That's why at first your phone can be at 0% for some time before it turns off. Then as it gets older the battery chemistry changes causing a much sharper decline near the end of battery life, which is why it starts turning off at 6%. Then when you plug in the charger it says 0%.",
"When a typical 3.7 volt smart phone battery is fully charged it actually will have as much as 4.3 volts, and when the battery is considered to be empty it will have 2.7 volts, so the phone only has to check the current voltage level of the battery to determine how much power is left."
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dogyzp | Why does it appear that, during a newscast, there is a delay at the studio end, but not at the reporters end? | What is the reason for this asymmetric delay? Intuitively I understand that it must appear to us to be instantaneous at the moment we perceive it, but I can't explain where the lost time goes. | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"We are seeing the conversation from the studio's point of view. Regardless of how long it's taking for the signal from the reporter to get there, we're seeing it arrive. When the anchor asks a question, we have to wait for that signal to get to the reporter and for the reporter's response to come all the way back. From the reporter's point of view, the opposite is true. They *could* rig it up so that we were watching from behind the reporter, and he was watching a feed from the studio. In that case, the studio feed would come in and the reporter could instantly respond, and then the delay would be in the studio acknowledging the response. Fun fact: the moon landings had to deal with this problem, as the moon is about 1.5 light-seconds away. Most of the footage we're familiar with has been edited to remove the delays, but if you can find raw footage (CBS streamed its real-time feed on the anniversary this year), it's been recorded from NASA's perspective and there's a delay between when Houston says something and when the astronauts respond. If we were able to hear the same recordings from the spaceship's point of view, the delay would be in the opposite direction."
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dohuzt | why does the shuffle feature on spotify still seem to group artists together? | I know that there's always a chance that in a 200 song playlist with 3 songs by a single artist that 2 or all 3 songs can play in a row but it still seems to happen far to often to leave it to chance. Plus I'm not the only one I know who has noticed this. Is there something about the programming that makes consecutive songs by the same artist more likely? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"The Spotify shuffle playlist actually is not fully random by design; people didn't like the fully random way before, I think because the situation you describe happens more often, statistically, then you would feel is right. Something like that. Let me find the article."
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dojii3 | What is the difference between two processors with the same cores and speed between a few years? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"CPU makers (like Intel) have learned a lot about how to make a CPU run faster. Most notably, rather than executing a single program instruction per CPU cycle, now they can look ahead and execute 2+ instructions at the same time (as long as they don't directly interfere with each other), slow operations will just take multiple CPU cycles and the system works around it, and when the CPU needs to wait for the result of a true/false calculation to make a decision it will take a guess which path is correct and not wait (with some pattern matching to improve guess accuracy) (this is how Spectre and Meltdown vulnerabilities came to be). Then Intel realized that the ability to run 2 instructions at once could be tweaked to make a single CPU core run 2 threads at the same time and have a net performance gain. This is hyperthreading. There's also other features a CPU needs to operate quickly that have improved. Memory is slow compared to CPU speeds, so there's a cache of recently used memory onboard. Some time around 2009 Intel started moving the memory controller off the motherboard and directly onto the CPU. And the list of instructions gets occasionally added to in order to make operations faster by having the CPU do work in a single instruction that previously required many, like SSE, AVX, and AES encryption. I'll end this list with the actual manufacturing process. The size of the parts inside the CPU have gotten smaller which means they require less electricity and run faster safely. Even for a fixed CPU speed, the reduced power consumption means more features can be put into the same chip while maintaining acceptable power and heat limits. There are all things that chip makers (with an emphasis on Intel and x86) have done to speed up CPUs over the years."
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domb3b | What exactly is fog computing and how is it different from cloud computing? Any easy examples? | Technology | explainlikeimfive | {
"a_id": [
"f5ov71o"
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"text": [
"A very rudimentary definition would be a network between devices and the cloud that helps do a lot of the computing to speed things up. For instance: The IoT (Internet of Things) is getting so dependent on other devices (think self driving cars talking to each other) that latency, speed of device and physical distance from the cloud can really throw a wrench into things. By inserting a layer of cloud just on the “edge” of the devices (read close), the information needed can be readily available. It’s kind of like buffering. This is the really rudimentary idea behind it and it’s full of holes, but it’s how it’s been explained to me for my business by people who want our business. So I’m really explaining like I’m 5, but I think you get the point. Now, let’s wait for the truly brilliant Redditors to beat up my description and explain it in a much better way! Think of this description as an hors d’oeuvre! TL:DR: A midway station that is physically closer than the cloud to help do the computing to speed up latency and account for distance."
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doo5u4 | We code computers so they can work, but how do the computers know to follow the code? Do we code the computer to follow the code given? If so, do we code computers to follow the code that follows the first code give...? | Technology | explainlikeimfive | {
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"Computers are really just a series of switches. Switches, organized in the right way, can do math (both of the traditional and boolean logic variety). For example, if you look up logic gates, you'll find circuit designs to process logic like \"Output is True (switch closed) only if A and B (two other switches are closed.\" Much more complicated circuits can do more traditional math (look up an adder circuit, for example). Your computer, fundamentally, consists of a processor, which can mathematically process a list of instructions, and memory, to store information. A program a human writes is translated into a list of mathematical instructions in a particular sequence for the computer to process.",
"CPU is built so that it does three main things: * It looks up instruction from memory, at address specified by *Instruction Pointer*. * it executes that instruction in specified way. * It adds 1 to the value in Instruction Pointer(moving it to the next instruction basically) The instructions CPU understands are built into the chip. The instructions themselves can vary between processors, this is where the word *Instruction Set* comes in, you may have heard it. In 90's and early 00's x86 was the instruction set for desktop PCs. Then AMD used it to make x86_64(also known as x64). Mobile devices use ARM instruction set. The cool thing is, by building your CPU so that it deals with instructions in some known instruction set properly, you can use programs made for that instruction set. Instruction set basically tells you how the instruction, which is a number, is interpreted. Like, if instruction pointer points to memory address that holds number like 50 in it, how would you interpret that? Instruction set tells you. How you can make CPU capable of following instruction sets in itself is a bit complicated. First off, physics part is a bit tricky. You can use pretty much whatever if you don't care about performance, like marbles rolling down a slope, but for high performance you want to use semi-conductors. I'm not sure exactly how semiconductors work tho. But whatever you do, you want to get to the point that you have logical gates built from semiconductors, marbles or whatever. Gates take input(which gets interpreted as a number), and outputs a number. Specifically, computers nowdays pretty much exclusively use binary numbers, 0 or 1. You can use various gates to build a computer. Notably, there are two gates which alone can be used to build all the rest of computer logic. I'll link a game where you can build your own CPU from NAND-gates. NAND-gates take two binary numbers in, and give one binary number out. NAND is short for Not-AND, it gives result of 1 always except when both(!) inputs are 1. If you can build this gate, then you can build a full CPU just by suitably stringing them together. URL_0",
"Simply, whenever a processor starts up, it loads the data in a specific location - often byte 0 - and teats it as an instruction. Some of the code is built into the chips design. The idea is the chip reads a value from memory, which is treated as an instruction - depending on that value, does things like pulling numbers from memory into registers and vice versa, doing arithmetic on values in registers, comparing things, and changing where the next instruction will be loaded from. Your program are just long lists of these instructions. Sometimes these instructions are looked up from a table of values written into the chip. Sometimes it is done more simply - the bits of the instruction - high and low voltages - directly turn transistors on and off, to reconfigure the chip to do the instruction."
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dos56l | What's the difference between a dynamic microphone and a condenser microphone? | I'm shopping for a microphone to record vocals and instruments, and every article about the difference between the two is just too much for my brain to handle. | Technology | explainlikeimfive | {
"a_id": [
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"A microphone is in a way the opposite of a loudspeaker. The microphone converts sound waves to an electric signal. The sound wave will exert some force on the microphone. In the dynamic microphone , the sound wave will push a membrane. (There is also a \"ribbon\" type mike, but coil is more common) A metal coil is glued along the membrane so that the metal coil will move with the membrane as the sound wave push it. When a metal coil moves in a magnetic field (the membrane and the coil is set in a magnet) it produces an electric current and that is the signal that you can run through an amp and out of the loudspeakers. An condenser microphone works a little bit different. Here, the sound wave pushes a thin metal sheet toward another metal sheet. And this creates a current (because two metal sheets are basically a condensator/capasitor). For the metal sheets to create a current you need a voltage, so condenser mikes need phantom power (voltage given from the mixing desk through the microphone cable) The membrane in dynamic microphones are a bit heavier than the metal sheets in a condenser microphone. So the condenser mike will follow changes in frequency faster than dynamic mikes. Condenser mikes are therefore better for higher frequencies like the overtones in vocals, the snare drum etc. Traditionally, one would use dynamic mikes like SM48 for vocals in a rock concert where the vocalist screams a lot but use condenser mike for the snare, piano or acoustic guitar/violin etc.",
"The main difference is that condenser mics are “electric” and dynamic mics are passive. What this means is that condensers need to powered by a special (48v) switch called “phantom power.” This allows them to be much more sensitive than dynamic mics. You need to be sure you have that switch on your mixing board or soundcard before attempting to use a condenser. You would use this style of mic in a quiet /controlled setting to typically record vocals and anything acoustic. Dynamic mics are on the opposite end of the spectrum. They do not require a power source to function. They are typically used to record anything that is loud or anything in a loud setting. They need to be positioned very close to the source to get a clear recording. You would use this style of mic on drums, guitar/keyboard amps, or live (powerful) vocalists. These mics are much less sensitive than their counterparts, however they are ideal for many applications where you need to isolate a specific source. Overall, most beginners would benefit from a high quality (more than $99) dynamic mic. It’s the most flexible option if you can only afford one mic. Over time you can begin to collect more mics for specific purposes but there’s no need to rush into that. You can always go to a professional studio to finish a project you started at home which will give you access to their large collection of gear."
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dos7hf | How did stores know personal cheques/checks were good in the 80s/90s? What were those little machines at the cash register they ran them through, and how did they work? | I remember my mom using personal cheques for everything from Walmart to gas stations. What kind of system was in place to electronically validate cheques in the 90s? | Technology | explainlikeimfive | {
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"There were clearing houses who assumed the risk of a check being bad, this protected the merchant who accepted the check. The merchant charged the customer a fee to accept the check. The merchant used the machine that scanned the checking account number on the check, contacted the bank electronically and asked the bank the balance. Essentially the merchant used an insurance company to guaranteed them payment for a small fee which was added to the consumers bill.",
"I worked in retail in the early '00s, which is close enough, really. For small values, usually _nothing_ was done to verify the amount. If the check was less than $100 or so, it just wasn't worth the time to verify funds. For larger values, there were check verification services that you could use. They would verify funding with the bank and give you an authorization number to let you know the check was good. If the service couldn't verify funds (which happened a lot) then the check was declined."
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doxzva | How are we able to tell the exact temperature of something so extremely hot or cold? | Like how are we able to pinpoint the temperature of something that is close to absolute zero or on the other extreme, millions and millions degree C down/up to its last digit? It can't be just an extrapolation, right? Do we work our way down (or up) step by step until close enough to the extremes? | Technology | explainlikeimfive | {
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"Well, high temperatures are measured by their black body radiation. We can measure the frequencies of light emitted by hot things, and use these measurements to determine their temperature quite accurately. Incredibly hot things actually emit specific bands of light, and the doppler effect stretches these bands out. By measuring this stretch we can see how fast the particles are traveling and thus how hot the thing is. I cannot speak to low temperatures, however."
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doyacq | How come cutscenes aren't preloaded in video games? Like a 4k HD video? | Technology | explainlikeimfive | {
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"It depends on how the cutscene is rendered (how it is drawn in the game). If it's a scripted cutscene, then everything is being shown in the actual game itself, which means everything has to be loaded as if you were playing the game even though you probably can't control anything except for the camera if that. If it's a \"computer-generated imagery\" (CGI) video, then it can load like a regular video file which cuts down on the amount of time needed to load and play it."
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dozfm3 | What even is a carborator for? | I feel like I've heard it in so many movies but don't know what it does | Technology | explainlikeimfive | {
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"On old vehicles pre 1990 for the most part it controls the amount gas allowed into the engine when you step on the gas pedal. In modern vehicles it’s be replaced by fuel injectors. It controls how much vroom vroom you get when you floor it.",
"*Carburetor. On older cars it is the device usually found on top of the engine that provides fuel to the engine when the accelerator is pressed. That fuel is mixed with oxygen at a specific ratio to make a combustible mixture the engine can use to make power. The fuel is drawn in with the oxygen by the vacuum created inside the engine. In other words, it is a complicated squirt gun for gas that some say works only by dark magic."
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dozm49 | Why is there a "ripple" whenever you push on a monitor screen? | Technology | explainlikeimfive | {
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"Most modern displays are LCDs. LCD stands for liquid crystal display. What that means is there is a very thin layer of liquid held between two thin layers of glass. These crystals align in specific ways to make colors. When you press them, they get shoved out of alignment to varying degrees giving you a rainbowy ripple effect. Edit: This got way more attention so I will elaborate to clean up some confusion. Note I'm just a tech hobbyist and I don't feel too confident talking about this that in depth, so take the word of the people who sound smarter than me replying over mine. As people have pointed out liquid crystals are really not liquid or crystals in the layman sense. Liquid crystal is actually an intermediate phase of matter. Think of them as tiny controllable filter cells. Little pockets of this magic light bending material we've figured out how to control. They bend light in *just* the right way if you can control their position and waves right. We get them to move into the right shapes with electricity. Someone below came up with a great example with polarized 3d glasses. If you hold polarized glass up to a light source and turned it you can see it block out specific bits at different angles. Monitors do this to align the light in a clean array that is manipulated to make a picture. Edit 2: Think of a bundle of straws. You hold them all and they are all nice and aligned and uninterrupted, this is white light. Push a golf ball into the center of that bundle and the light can no longer travel in the right direction. Depending on the angle of the light (again this is a really boiled down version) you see different colors. All of the straws are bent to varying degrees around the ball (or your finger).",
"What about when you see colors when you put a magnet close to a crt television?",
"As others have stated what LCD stands for - you are moving the liquid around. However more and more displays no longer use the liquid crystals. OLED, microled, qdled and similar are basically millions of tiny lights instead.",
"If you kept pressing on the screen to make ripples can you damage the screen from repeat poking?"
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dp3r28 | If rebooting is turning a system off and then back on again automatically, how does the system turn itself on while being off? | Technology | explainlikeimfive | {
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"Whether or not your computer is \"on\" ( power states of the computer) are controlled by something called the ACPI (Advanced Configuration and Power Interface). When you tell your computer to \"shut down\", the operating system tells the ACPI to stop all processes. However, your computer does not actually completely power down, it has some stored juice with which it can restart itself when asked. This is called a standby power supply. The power button these days does not actually physically stop electricity to flow into the computer, it just tells a subroutine to go into a standby and wait for a new input to restart itself. At the end of a shutdown process, your computer tells the ACPI that the computer should reboot. When this happens, the components are reset with commands stored in them by the bootstrapping process (booting, as it were). So in other words, as long as the power is connected these days, the computer never actually turns off, it only resets various components and then behaves as if it was turned off.",
"Unless you pull the plug, it's not really fully off. The power supply in the back keeps some electricity going to the computer to allow it wake it up when you press the on button."
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dp5a1v | Why Do some Lights tinkle when they Light up? | Okay so I'm not a native speaker so I hope I can translate my Question correctly. Some older Lights Do this little high pitched sounds (kinda sounds like icicles falling on ground) when you switch them on/when they light up after. What produces that Sound? | Technology | explainlikeimfive | {
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"If you mean fluorescent tubes, older fluorescent fixtures used a system which featured a bimetallic starter (the small, round, silver piece). Inside the starter is a bimetallic switch which \"pings\" when energized. Newer fluorescent systems, such as the \"preheat\" or \"rapid start,\" are rendering the \"ping\" a thing of the past."
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dp5uqt | how does editing software distinguish so easily between greenscreen and non greenscreen? | Technology | explainlikeimfive | {
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"It's called Chroma Key compositing. You look for colors in certain ranges and replace them. So with green screen, you replace everything in a particular range of green colors (this is how you handle shadows, etc.) When done incorrectly (either with an incorrect color range or someone wearing a color in range), you get images like this: URL_0"
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dp6f41 | Why do radios, bluetooth speakers, earphones, etc lose signal or crackle when you’re under electricity cables/lines? | Technology | explainlikeimfive | {
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"text": [
"The massive amounts electricity create an electromagnetic field that disrupts the signals of these devices bluetooth & phone signals (microwaves) Radios (radio waves) All of these devices use electromagnetic waves to communicate, so the powerful electromagnetic field badly distorts the signal"
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dp7i09 | What is Machine Learning? What is Cluster Analysis and Dimensionality Reduction? | I understand quite a bit about technology but I never understood how machine learning works. | Technology | explainlikeimfive | {
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"Machine Learning is, in some sense, simply a branch of statistics. It is a general term for the process of determining a function based on analysis of *training* data, which can then be applied to *hidden* data (i.e. data which hasn't yet been seen, possibly because it hasn't been created yet). In normal computer programming, you (the programmer) tell the computer exactly what to do by writing functions which, when applied to inputs, yield the desired output. Sometimes though, those functions are very hard to write (like recognizing the difference between a cat and a dog in a picture), and this is where machine learning can help. Conceptually, rather than writing these hard-to-write functions by ourselves, we can give the computer a bunch of data and ask it to learn about the commonalities in that data. Let's imagine a very, very simple example. Imagine we're trying to write a program which determines whether or not a light is on in a room. We have access to an ambient light sensor which gives as its output a number: higher numbers indicate the room is brighter, and lower numbers indicate the room is dimmer. This would be a very easy function for us to write by hand: lightOn :: Double - > Bool lightOn brightness = brightness > 0.5 Or something like that. If the brightness is more than some threshold, then we say the light is on. Otherwise, it's off. We can view this problem in machine learning terms. We have one data point to work with, the brightness, which means that the *feature vector* of our problem has order one (i.e. one component). This also means that the *dimensionality* of our problem space is one. Geometrically, we're looking at a line. Data points further to the left on the line have lower brightness, data points to the right on the line have higher brightness. What we need to do is figure out where on the line to draw our *discriminator*, which is to say, the threshold above which the light is \"on\", and below which the light is \"off\". In the implementation above, it was 0.5. I just made that number up. If we were doing this with machine learning, we would have a ton of sensor read outs from different rooms, paired with whether or not the light was on in each room. Then, we would look at that whole corpus of data and determine, statistically, where the \"cutoff\" is between \"on\" and \"off\". This would be our separator. Now this is a very, very simple example. In more complex examples, the feature vectors may have dozens or even *hundreds* of components. Deep Learning models often have *thousands* of components in their feature vectors. The more components you have, the more dimensions in your space. In all cases, though, you're still trying to draw a \"line\" to separate the \"yes\" answers from the \"no\" answers (when writing a true/false discriminator function). Of course, as your dimensionality goes up, so too does the complexity of your dividing \"line\". If your feature vector has one component (as ours does above), then your diving \"line\" is just a point. If you have two components, then it's a line (and it might not even be a straight one!). If you have three, then it's a plane. At higher dimensions, we stop giving them names and just say \"hyperplane\". Either way, hopefully it's clear that the data you're training on (and ultimately applying the function to!) is mapped onto points in higher dimensional space, and the discriminator function reduces the problem of figuring out yes/no answers to a geometrical problem of determining whether the point is above or below the separating hyperplane. Note that you can generalize this slightly by also producing the *confidence* that a certain input is a yes (or a no) result, where that confidence is calculated based on how far away from the hyperplane lies the data point represented by the feature vector in question. Of course, not all problems can be phrased in terms of yes/no. Speech recognition is a decent example. You can't possibly have hundreds of thousands of yes/no discriminators, one for each word in the English language. So instead, you will use cluster analysis. Instead of producing a function which says \"yes/no\" in response to an input, you'll produce a function which returns some result based on a finite set of possible answers. This is *still* a very geometric process! Again, think of data points in space, where each data point is some input represented by a feature vector. Some of those data points will be close to each other, and far away from all the others, forming their own little island where the density of data points in space is higher. There could be *many* such islands. In terms of speech recognition, the distance between the islands probably corresponds to how much the words sound alike when spoken in a \"normal\" accent. For example, \"dough\" and \"throw\" are probably very close together, but \"fight\" and \"war\" are very very far apart (because they sound so different). *Clustering* is the process of, again statistically, figuring out the size, shape, and position of all of these little islands. The goal is that you should be able to take some input, compute its feature vector, and figure out which island it is *closest* too. That island becomes the result of your function. BTW, in modern speech recognition techniques, this process is actually considerably more layered. What is generally done is you have a preliminary clustering model which first classifies the *audio* into strings of *phonemes* (since most languages only have about 30-40 different phonemes). These these models are tricky because they need to take into account *time*. If you hear the term *convolutional*, you'll know that you're probably about to hear something about temporal or spatial invariance. Once you have a stream of phonemes (note: each phoneme will have a confidence score, and for some phonemes, there may be multiple possible answers!), you can feed *that* stream into the next stage in the pipeline. This could be a hard-and-fast grammar model (pioneered by Noam Chomsky), or it could be another classifier which attempts to chunk up those phonemes and classify them into words. Note that this model *also* must be convolutional since it may be uncertain about what a particular word might be until it hears the *next* word, which clarifies things. For example, distinguishing \"dough\" and \"throw\" is difficult until you hear \"the ball\", at which point you know with absolute certainty what the first word was. Computer speech recognition functions work the same way. Anyway, hopefully that gives you a general idea of where these terms come from and what they pertain to. When in doubt, always think geometrically. Almost everything in machine learning comes down to computing hyperplanes in hyperspatial problem domains with sparse data points represented by feature vectors."
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dpafar | If you can't type on a phone while using gloves, how can you butt dial? | Technology | explainlikeimfive | {
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"The screens work by picking up tiny electric currents that pass through our skin. The cloth in gloves prevent that electricity from reaching the screens. When sweat from your body soaks into the thin fabric of your pockets, enough of those tiny currents can pass through to operate your phone.",
"Phones don't detect your fingers touching them - they detect your fingers getting really really close. You actually can use your phone with gloves on, so long as they are thin enough. This includes very thin fabric gloves or plastic medical gloves. You can also use your phone through a sheet of paper or tape. This means that sometimes your phone will detect your butt through the fabric of your clothing. Admittedly, it is rare, but also very much possible."
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dpg9e8 | Is it better for your eyes if a screen is too bright or too dim, and why? | Technology | explainlikeimfive | {
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"text": [
"It's best if the screen matches the surroundings. A bright screen in bright light means it's easier to see, and less work for your eyes. A dim screen in low light prevents too much light harming your eyes from a directed source."
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dpi9f7 | When a MAC dies and you plug it in, it turns back on within seconds. When an iPhone dies, it takes several minutes to turn back on. Why? | Technology | explainlikeimfive | {
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"Phones often use their battery as a buffer between the charger and the actual circuitry of the phone. If the phone is drawing more power than the charger can put out, the battery helps out and supplies the rest. In order to do that there needs to be a certain amount of juice in it. Without enough reserve power in the battery, the phone may not be able to complete the boot process without dying halfway through. Laptops have more generously sized power supplies that can put out enough power to run the laptop and charge the battery at the same time. Phones have a low average power consumption, but the peak power consumption when the phone is working at 100% load (like when booting) can be quite high, and the charger on its own may not be able to cope with the peaks, even if they only last for fractions of a second. There's also the fact that (unlike a laptop) phones need to be compatible with all sorts of aftermarket chargers, so they can't just assume that a charger can reliably supply a certain amount of power. Requiring a certain minimum battery charge level before allowing the phone to turn on ensures that the phone will boot successfully even if it's connected to a crappy charger.",
"Phone and laptop batteries are wired a bit differently. In laptops, the power circuits are capable of powering the laptop AND charging the battery. in phones the power circuit charges the battery and then the battery powers the phone, so the charging circuit can't power the phone and the battery at the same time. So the battery needs to charge a bit before the phone can turn on. This is due to space. There's just more room in a laptop so larger, more complex circuits can be used."
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dpm5re | What is fuzzy logic and how is it that it's found in missiles and rice cookers? | Technology | explainlikeimfive | {
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"Traditional logic only knows two states: True or False. Is the rice cooker hot enough? If yes, turn off the heating element, and if not, turn it on. Fuzzy logic can also express to what extent a statement is true on a sliding scale. Is the rice cooker hot enough? No, but it's close, so turn down the heating element a bit. In a lot of control systems that extra information can be beneficial because it allows the control logic to make better decisions. In the rice cooker for example the heating element has a certain amount of thermal mass, and even if you turn it off, it will remain hot for a few moments and continue to heat the rice even without power going to it. That means you will overshoot the desired temperature by a bit if you keep it powered at 100% until you reach the target temperature. And if you keep it at 0% until the temperature falls below the target, the heating element will need a few moments to heat up when you do turn it on, so there's going to be undershoot as well. So instead of maintaining a constant 60°C to keep the rice warm, the actual temperature may oscillate between 57°C and 63°C. If the controller is smart enough to reduce the output of the heating element when it approaches the target temperature, there's not going to be as much overshoot.",
"Fuzzy logic is a simple hack. It allow to answer imprecise questions with imprecise answers. For example: are you old? If you are 3 year old, most certainly not, if you are 97 year old, most certainly yes, but what if you are 50? Well, you could say yes and no. It is used when we improving cheap automation. Rice cooker are super simple and need to answer: is the rice cooked yet? Well, if you just started the answer is no; if you are at it for 25 min the answer is yes; but what about 20 min? Well, the rice cooker will say: no below 15 min, mostly no below 18 min, kinda below 20, mostly yes above 22 min, and yes above 25 min. From that fuzzy \"confidence\" it will decide how hot it should be so as to either cook, or simply keep warm. For missiles it is used in the flight control. When the missile is flying it has to keep on the path it is supposed to be, but if it ends up a few centimeters off, you don't want to do a 90° turn to correct, you want to do only a few degree correction. If you are a few kilometer off, you will want to do an almost 90° turn. Usually, the fuzzy logic is used when being precise does not matter too much (no need to make the question super precise) yet you don't want to be too abrupt in the answer (because changing the answer from all to nothing is expensive if we are just in the range of \"maybe\").",
"Are you old ? (if I am 50 year old) Binary logic: YES if AGE > 60, otherwise NO. So I'm not old. Fuzzy logic: AGE/60 % old. So I'm 83% old. Fuzzy logic is more analogic than usual binary logic. Binary logic has threshold effects that can pose problem. Fuzzy logic is less deterministic, you know approximately what the machine will do, but not exactly since there are too much factors. With multiple variable you get equations like, 83% A \\* 10% B \\* 38% C... so the result can be... Turn 43% left. No one predicted it was 43%. And maybe it would be more effective to turn 45% left but whatever it's better than either continue straight or turn 100% left.",
"To your question about machinery using it, I am not an engineer. I am going to assume that the rice cooker is using a boolean approximation of fuzzy logic. Fuzzy logic is a system of logic that shows \"how close\" a statement is to being true. Unlike boolean logic, the system can rely on more dynamic assumptions and produce more useful results. Suppose I gave you a reddish ball, and I said \"this ball is red.\" You may have no trouble agreeing with me if it is a pure red ball. But what if the ball had a little blue mixed into the pigment? Depending on how much blue is in the ball, we may start disagreeing that the ball is red. A fuzzy way to solve the problem would be to agree that the ball is somewhat red. This involves defining redness on a sliding scale (perhaps as a ratio of red to blue?) and then using that definition to come to a decision. Fuzzy logic is quite a common way of thinking about things. It lets us challenge definitions that are taken for granted without reaching a dead end in that challenge.",
"Fuzzy logic takes a bit of discrete maths and a bit of regular maths and mixes them together. More specifically, it says that things can not only be true or false, but also true-ish, or mostly false. In this sense its more like normal maths because the values can take any value between true and false (1 and 0) for example 'its going to rain today' might be a 0.312 ie mostly false but also might be a bit true. Its more like logic in the fact that it uses traditional logic operators instead of arithmetic operators. Its used more nowadays because it more closely resembles the real world. Inputs to a system are rarely entirely true or false, so rather than having to make a yes/no decision at the input stage, its better to have the 'fuzz' of the input propogate through the system and influence its internal states.",
"IMO, fuzzy logic was a buzz word in the field of AI a couple decades ago and now a lot of people try to affix the nomenclature to various problems that have already been solved by other means. Humans tend to create new nomenclature for things that are already named. If someone can't tell you what some complex sounding nomenclature means in a couple sentences, that usually means that all there is to the subject is complex nomenclature.",
"The missile knows where it is at all times. It knows this because it knows where it isn't, by subtracting where it is, from where it isn't, or where it isn't, from where it is, whichever is greater, it obtains a difference, or deviation. The guidance sub-system uses deviations to generate corrective commands to drive the missile from a position where it is, to a position where it isn't, and arriving at a position where it wasn't, it now is. Consequently, the position where it is, is now the position that it wasn't, and it follows that the position where it was, is now the position that it isn't. In the event of the position that it is in is not the position that it wasn't, the system has acquired a variation. The variation being the difference between where the missile is, and where it wasn't. If variation is considered to be a significant factor, it too, may be corrected by the GEA. However, the missile must also know where it was. The missile guidance computance scenario works as follows: Because a variation has modified some of the information the missile has obtained, it is not sure just where it is, however it is sure where it isn't, within reason, and it knows where it was. It now subtracts where it should be, from where it wasn't, or vice versa. By differentiating this from the algebraic sum of where it shouldn't be, and where it was. It is able to obtain a deviation, and a variation, which is called \"error\" source: this video URL_0",
"I work in a place that makes plastic parts. On our old machines the heaters are just on and off. If the heater is at 399° and you want 400°, the heater comes on 100% power until it sees 400°. Then it shuts off and stays there until it sees a temperature below 400° again. The problem is that with heaters and sensors, you have a delay between 100% heat and when the machine senses 400°, so even after the heater turns off, you might climb all the way to 420°. This is extremely inefficient and can cause problems with plastic that is very particular about temperature. On our newer machines, they use fuzzy logic to say \"The machine is 200° so we should run the heats on at 100% because it's 200° away from the setpoint.\" Then at 350° it says, ok, we're almost there, let's pulse the heater power to 75% so that we don't overshoot the setpoint. Ok, now it's 395°, start pulsing the heater at 10% power until we reach 400°. Ok, now if we pulse a constant 5% power, the heater stays at exactly 400° without any other adjustments. This method is much more controlled and much more efficient than the old method of 100% on or 100% off.",
"Fuzzy logic has two meanings. Informally, it refers to an inexact but useful calculation. A mapping programming can't give you the guaranteed shortest route, that is actually a very complicated calculation, but it does know things like \"turn towards your destination\" and \"get on the highway if possible\" are likely going to give you better route, if not always. Formally, it refers to a logic system where instead of a proposition being 1 (true) or 0 (false), it can take on any value in between. Conceptually, it is more like hot vs. cold than true vs. false. This is useful in complex systems where answers represent subjective estimates based on multiple data inputs, like medical diagnosis or weather forecasting.",
"Mostly, marketing bull. But I'll let the late great Bob Pease give you some learnin'; [ URL_0 ]( URL_0 )",
"The best explanation I heard of fuzzy logic was \"How many grains of sand do you need to make a pile of sand?\" It's clearly more than 10, certainly less than a million, but what's the difference between 388 and 389? Is one a 'pile', and the other not? The answer usually depends on the person being asked. Similar fuzzy questions: \"Is Tom tall?\", \"Is Sheila fat?\", etc. The answer is usually some type of \"S\" curve, where almost everyone would agree, for example, that an adult under 4' is \"short\", and one over 6'6\" is \"tall\", but for people in between, the response will be some number greater than 0 (short), and 1 (tall). I'm 5'10\". Perhaps only 2 out of 10 people would say I'm tall; my score would then \".2 tall\". Just as you can perform calculations with traditional Boolean logic, you can perform calculations with fuzzy logic. The rice cooker might be able to sample the internal and external temps, the humidity, etc. (I really don't know the algorithm, so guessing here) The fuzzy calculations then determine if the rice cooker must increase or decrease heat.",
"Traditional computing logic is boolean logic. It makes decisions through a series questions that have a true or false answer. For a rice cooker, it can be a series of \"is the temperature in this range?\" questions to determine when to lower or stop the heating element. Or \"does this moisture sensor read below X%?\" type questions to be \"smart\" about when the rice is done. These questions can be very complex, such as with a [PID controller]( URL_0 ) that is using this sort of logic to determine what to do based on the outcome of an equation. These systems are very powerful, but they are rigid -- the checks and equations all boil down, ultimately to a finite set of states and the actions that should be taken based on them. That doesn't always suit the messy real world, though. Fuzzy logic is logic that deals with _how true_ something is rather than simply if it's true or false. It arrives at the \\_probability\\_ that something is true when we can't decide if it's really true or false. It's used when there are a bunch of inputs that we know have a high error rate/are otherwise untrustworthy. For example, missile controllers use fuzzy logic because their many sensors can slightly disagree -- and the \"fuzzy\" logic is a set of systems that try to reach a consensus about what's going on with some level of confidence. For example, \"am I on course?\" -- all the sensors say \"no, not exactly\", but taken together they don't indicate any specific error. The fuzzy logic system can say \"there's a 98% probability I'm on-course _enough\\ that I don't need correction, I'm taking no action\". Likewise, a rice cooker could have multiple sensors that measure things that correlate to the rice being correctly cooked. It can't _guarantee_ it, but it can say \"while the sensors don't _agree_, they agree _enough_ that I'm confident the rice is done and I should stop\". Although, to be fair, a lot of things that _claim_ \"fuzzy logic\" are not using fuzzy logic at all, and are just capitalizing on the association between \"fuzzy logic\" and machine intelligence.",
"Normal logic in computers is based upon absolutes yes no or one two, which computers find it really easy to calculate and operate with, however the real world is rarely that precise or defined so the number maybe somewhere between one and two and the precise number might not be known, but the range which it occupies might be known so the number is blurred or fuzzy as it can't quite be seen or identified.",
"Fuzzy logic is reasoning about propositions that aren't just binary true or false, but can take on any truth value in a range between 0% \"definitely false\" and 100% \"definitely true\", usually interpreted as a probability value between 0 and 1. Fuzzy logic connectives then are functions which combine a continuous range of truth values in the range 0 to 1 and produce a truth value in the same range of 0 to 1. Of course, there is no need for the truth values to literally be interpreted as probabilities, they could just represent intensities etc or something more abstract, but they always lie between 0 and 1 and mathematically they are handled like probabilities, so that when combining values with fuzzy logic connectives, we should do so usually continuously or in other ways we can understand and analyze, and always in a way that gives outputs again in the range 0 to 1. Some operations you can consider are linear blending: like taking half of X and half of Y and adding them together, or blending in any other linear combination whose norm is 1. But you can also combine with other connectives that are non-linear. For example, given two propositions X and Y with some truth values, we can consider bilinear functions like MIN(X,Y) which returns the minimum value of X and Y, MAX(X,Y) which returns their maximum, or the linear function of one variable NOT(X) which returns 1-X. If X and Y took only values 0 and 1 discretely, notice that these connectives recover the usual Boolean connectives AND, OR, and NOT, respectively. Another interpretation of AND(X,Y) could be given by the fuzzy logic connective MULT(X,Y)=X\\*Y. This is still bilinear but behaves differently than MIN(X,Y). Similarly note that there are many more unary connectives now, functions like sigmoid functions which increase confidence that something is either definitely true or definitely false, or functions like X\\^2 and X\\^3 which act like lowering confidence of true outcomes. It's obvious how fuzzy logic could be useful in domains like rice cooking and missile guidance, since these devices need to reason about values between definitely true and definitely false: questions like \"how close am I to my target\", \"how high priority is this target\", \"how fast am I moving\" etc all clearly take a continuous range of values, but are the things which clearly have to go into the logical control of the device. Notice some of these problems also need other areas of math to help solve, such as Calculus (how fast am I going, how fast am I accelerating/decelerating etc), which aren't exactly the domain of fuzzy logic, but do give signals which take on continuous values and can be reasoned about using fuzzy logic, or perhaps more restrictively using very constrained subsets of fuzzy logic operations (in which case often we don't bother using the term \"fuzzy logic\" to describe them). Notice that fuzzy logic clearly doesn't satisfy the usual laws of *classical* propositional logic, since in classical logic we always have for truth values X that either X = 0 or X = 1 (the \"law of excluded middle\") and obviously fuzzy logic's whole point is to violate that by introducing a lot of \"middle\" ground. However, most fuzzy logics extend basic *intuitionistic* logic (also known as *constructive logic*)."
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dpo5qw | How do controllable prosthetics work? How does the brain control something that's artificially attached? | Technology | explainlikeimfive | {
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"Simplest prosthetic is where you just lost your hand. Since basicly all muscles controlling the hand are in your arm you can just put sensors near those that detect activity and rig it up to the right limb. It gets harder the more is lost, but the principle is the same. Find an unused nervbundle/muscle group. Put a sensor on it to control the arm. Doesn't even really have to be the same nerves that controlled the original arm because the brain can be retrained.",
"We're capable of creating neural networks that can translate brain waves or electrical impulses in the target appendage into actionable information. In other words, we measure the brain waves/neural impulses of the person as they repeatedly think of doing an action. The neural network learns to associate those signals with whatever output we designate (i.e. think of curling your index finger - > run actuators to do exactly that). The Myo armband used the same technology to allow users to issue commands to devices using arm/hand gestures."
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dptj81 | How does my phone's touchscreen work? | Technology | explainlikeimfive | {
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"Your body conducts electricity. The phone's screen is able to sense that electricity. When you touch a spot on your screen, it sends electricity to that spot",
"When you touch the screen a small electrical charge gets transferred to your finger to complete a circuit and that creates a voltage drop on that point of the screen. The software then processes the location of the voltage drop and does what it supposed to do.",
"There are two major types of touch screens, capacitive and resistive. Most phones use a capacitive touchscreen (don't worry I will explain these so it becomes ELI5, I am just introducing terminology) Capacitive touch screen: for these types of touch screens when you move your finger near the capacitive layer it will cause the charge to build up where your finger is located. This will be detected and thus every location where charge has accumulated it detects a touch. Furthermore we can calibrate the sensors to only account a charge build up if it is similar to that which would be produced by a finger which is why other things that could also cause a buildup of charge do not work. For capacitive touch screens you usually don't have to actually touch the screen for it to register and if you are very careful you can have it register a touch without actually touching it. Not that this adds any benefit. Resistive touch screens work differently and can also detect multiple touch locations if configured to do so, though some will not be able to. These touch screens work by having 2 seperate flexible layers that are just barely not touching with a conductive coating (or rather a resistive coating cut any conductor will have some amount of resistance) on either side. When you touch the screen you will deform it and push it so that the conductive layers touch and a circuit is completed. This allows you to detect said touch. A big benefit to resistive touch screens is that they can work with anything touching them, including non-conductive gloves. Since 2011 most consumer touchscreens have been capacitive but in many industrial settings where it is dangerous to not wear things like gloves you will still find resistive touch screens This is simplified."
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dptnhy | How can my smartwatch differentiate between my steps and my tapping to a song's rhythm ? | Technology | explainlikeimfive | {
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"A lot of them can't. But, in some models there's a tiny metal ball on a slightly magnetic circular surface, and \"swinging\" motion is tracked differently than the \"erratic\" motion of other things.",
"Sometimes they can't. Friend of mine got over two thousand steps while he was in the shower. O_O",
"Ive been fighting with accelerometer algorithms for a few months now. I can tell you with 100% certainty, that your watch cant tell with 100% certainty that youre taking steps. If you download an accelerometer app for your phone, you should be able to look at a graph of the accelerometer data. If you hold your phone in your hand and walk for a bit, you should see a chart of what your watch \"sees\" on the accelerometer. If you then try tapping to a rhythm, you can look at the chart and it will be different in ways that you might be able to visually pick out. Perhaps you keep close time to a fixed beat, your movements are smaller, or larger, but certainly different. Certain algorithms can guess if the accelerometer data represents walking steps, and can count those steps. They are not very accurate. Try walking 100 steps and see how many steps it counted. Then try tapping to a beat. The other comment about the metal ball isn't accurate for smart watches. A device like the MPU9250 is much more common."
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dpuncb | How do the Ring Doorbell servers not get overloaded on Halloween from all the Trick-O-Treat-ers? | it would seem like with all the rings that all the data would crash the system, how do they prepare for something like this were almost every door bell in America is getting rang many times for a few hours? | Technology | explainlikeimfive | {
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"A lot of the data is local. Somebody rings the doorbell, it sends video over your wifi network. There is a subscription service, and that does use servers with ring, but that isn't really an issue, since they are owned by Amazon, and Amazon has a lot of cloud servers. The servers are designed to be able to scale. When they are nearing capacity, they call in another server. Amazon can assign the server to them, then when usage goes down, they take it back, and send them a bill. Amazon is massive enough that on an overall system usage, they won't even notice a change (perhaps system wide, amazon would see lower usage, as most people are out, or passing out candy)."
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dpwv9h | Does a power cut affect phone data? | I live at a student accommodation and a few days ago, we had a blackout. All power went off meaning I had no access to WIFI. I decided to turn on my data (4G) just to scroll through the internet. Instead, the data I was using was 3G and when I opened apps like Instagram and Reddit, they loaded pretty slow, if not at all. Does a blackout affect my data? Or is there something wrong with my provider? | Technology | explainlikeimfive | {
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"This is a likely indication that the tower you normally get your 4G coverage from was also affected by the outage.",
"It may be that your student dorms normally operate a cellular repeater in order to increase the strength of cell service in the area. A power cut could take out that repeater meaning you need to connect to a more distant tower. It is also possible that you were not alone in wanting to browse the internet and all the normal traffic that would be through WiFi was overloading the towers.",
"Two things. First, the providers likely have some power backup but it's not indefinite. At some point they will stop transmitting due to a power outage. Second, capacity of a cell site has a limit. You were very likely not the only person that started to use the mobile network when the power went out. That would cause the system resources to be more heavily used than typical. Some users would be handed down to 3G or even 2G to handle the additional user count."
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dpy27s | for what reason does technology turn off when too cold? | Technology | explainlikeimfive | {
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"text": [
"Batteries operate off of a chemical reaction that is facilitated by heat. The lower the temperature the less power output it has, until it is below the voltage threshold for the device to run."
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dpz1mn | How can the chance of rain be 10% when it’s pouring outside? | Technology | explainlikeimfive | {
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"Forecasts are done over an area, not a point location. It might be raining at your location but not 2 blocks from you. The percentage is the chance of some place in the area of the city or whatever defined region getting rained on.",
"That's not how probability works. It means that if you had the same day 100 times, it would only rain for about 10 of them. It doesn't mean the rain will be less intense, it means that it would be less frequent."
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dpzsxh | How to internet service providers, manipulate how fast or slow your internet connection is without any of their software on your device? | I've noticed some local ISPs have different rates for different speeds. How do they do accurately choke your internet connection without having to do anything to your device? | Technology | explainlikeimfive | {
"a_id": [
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"Imagine a water hose. On one end is connected a garden sprayer. The other end is connected to the water faucet. If you squeeze the handle, you can control how much water comes out the sprayer. But the guy standing at the faucet can begin reducing the amount of water coming to the sprayer. If he reduces the water enough, it doesn't matter how much you squeeze the sprayer. The water is your internet speed. You and your sprayer are all your internet gear (modem, router, etc.). The guy at the faucet is your ISP.",
"Your internet access goes through them, they don't need access to your device. They control your traffic directly: you send data to them, they relay it to the rest of the internet at whatever speed you pay for. When you download something, they relay that data from the source back to you at whatever speed you pay for."
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dpzu22 | When there is a really windy and bad storm, my lights dim and flicker, but the power doesn't fully go out. Why not? How do the lights dim as if they get less power, it seems like they are either getting electricity or they aren't? | Technology | explainlikeimfive | {
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"text": [
"Usually it's because lines are swinging around causing intermittent faults in the system that temporarily drop the voltage."
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dq0pzo | If Extreme Ultraviolet Lithography is the breakthrough technology in chip manufacturing which can make 13.8nm chips, how does AMD and Samsung Exynos achieve 7nm? | Technology | explainlikeimfive | {
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"Complicated answer, unfortunately. The first thing you need to know is that those node names don't really mean anything anymore. New nodes used to mean that you shrunk the lithography and device by 0.707, because that would result in a 50% area shrink. Which meant for the same size chip area, you could cram in 2x the shit, or make the same chip half as big (doubles your wafer yield, big for the money side of it). This is basically Moores law. At the 22nm node, it became too difficult to really do this anymore, and the node numbers stopped representing actual device shrinks for 2 reasons. Reason 1 is that that you can't just scale the unit device, you also have to scale the \"back end\" metal (ie the metal lines that connect the transistors). If you just shrink the transistor, but the back end doesn't shrink too, you won't see a full 50% scaling. It may sound easy but making smaller metal holes and lines, but at 22nm was really hard, and needed new tooling and materials. Ever since this period, any one not named Intel will come out with a new, \"smaller\" node, but if you actually look at the press release, it's only like a 20% or 35% area shrink. I am by no means an Intel fan boy, what they did to AMD was disgusting and I refuse to buy electronics with their parts in them. But Intel really sticks to the heart of Moores law and won't release processes until they get a 50% shrink. Reason #2 is that transistors stopped being planar (meaning they switched from being like a sheet of paper flat on a table to being a sheet of paper standing on one of its edges (standing up like a \"fin\"). So the node name stopped meaning the gate pitch, and really just became a marketing term. Now on to your actual question, which SHOULD have been, how did they make 32nm or 14nm transistors with 193nm wavelength lithography? The answer comes in the form of many tricks, most of which will bore you. But the heart of your question is answered by something called \"self aligned double patterning.\" I could go on to explain what this is, but frankly it's a bit in the weeds and a Google image search can explain it better than I can right now. The important point I want to make is that these people like Samsung and TSMC don't actually use euv for the heart of their processes. It's not mature enough yet and doesn't have the cost or throughput to be used to form the actual transistors. They are instead using euv at cut mask steps where the can see a little benefit and continue helping the euv technology grow. So please don't think that euv is what is being used to make those chips. In conclusion, because I'm tired of typing on my phone, don't pay attention to the node names. It's just marketing and doesn't represent any physical dimension any more. But how do people make things that are well below the resolution limit of the lithography (which most definitely does happen and is marvel of fucking engineering?) SADP. EDIT: I felt like a jerk, I'll explain SADP. Imagine you want to make holes in a tortilla, but you want to make them smaller than you can actually print? First you put down a layer of playdough, and cut lines in that playdough at the smallest pitch you can. So now you just have really small lines (or pillars) of playdough on your tortilla. Next you put down a really thin layer of material very uniformly, like a piece of saran wrap that you put a hairdryer on. So now you have a thin layer of saran wrap coating all the playdough pillars and the exposed, open areas of tortilla between pillars. Next you \"etch\" the saran wrap, which you can think of as nanoscopic sandblasting. What happens is that the saran wrap at the top of the playdough pillar gets removed, and the saran wrap that was covering the exposed tortilla gets removed. So now that you have the top of the playdough pillar exposed (the sides are still covered in saran wrap) you dip the tortilla in a chemical that only removes playdough. What are you left with? these even smaller pillars of saran wrap that are now spaced much closer than you could ever do with playdough. You then sandblast the tortilla was a chemical that doesn't attack saran wrap, and you get holes at a smaller pitch! Hopefully that makes sense, because I'm not going to try again until tomorrow or if someone complains in a way that makes me feel bad about myself."
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dq0qcs | When a video game crashes and/or freezes up, why does the music continue to play? | Technology | explainlikeimfive | {
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"When a video game runs it creates various processes of the same application. One process displays images, one runs audio, and various other processes for various tasks. When the game freezes only certain processes crash. The game is still in the RAM but the process has crashed. In some cases the audio process does not crash but other process crashes because of some some reason. At that time the audio process keeps running while the game is frozen.",
"PCs or other video game devices generate images on the screen with their graphic cards, and generate sound with audio cards. When the graphic card crashes, you'll see the image crashes and/or freezes up. But as long as CPU and audio card is still working, you can still hear the music. In this situation, your device is just like a man who fails to draw and/or write but still can speak.",
"Many programs, not just games, are multi-threaded. A thread (or process) is like a job being done parallel to other jobs. Often programs will encounter a bug or crash in one thread while the others continue to run. As others suggest, Audio, Graphics, and 'the game engine itself making the actual gameplay' are on different threads. If one fails, the others may continue on merrily unaware of what went wrong with the failed thread.",
"Assume you've invited two your neighbour friends to make a school play for all parents. One of your friends performs visual part of the show, another one - plays the piano and he is not aware what's happening behind his back. And one, who performs the visual part just fails for whatever reason, another one will continue playing the piano. Roughly speaking that's how it happens when your video game glitches."
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dq4lfg | Why are most classical calculation not possible to be accelerated through quantum computing? | > From Wikipedia, "The capacity of a quantum computer to accelerate classical algorithms has rigid limits—upper bounds of quantum computation's complexity. The overwhelming part of classical calculations cannot be accelerated on a quantum computer". From what I understand, calculations like integer factorizing a semiprime can be calculated much faster with quantum algorithms, so why wouldn't the same apply for all calculations? What are some examples of calculations that cannot be accelerated by a quantum computer and why? | Technology | explainlikeimfive | {
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"So with quantum computers you have qubits instead of regular bits. The cool thing about qubits is that they can exist in a super position of a bunch of different states at once, which means they can do also do a bunch of calculations at the same time while in this super position. The problem is once you try to measure these qubits the superposition collapses. The qubits pick one position to be in at random, and so you get the one output for the one position they happened to settle in. For most regular computation this isn’t really useful, you still get one output and it’s random, so they don’t really offer any benefit over a regular computer (and actually have substantial drawbacks). If the problem is 2+2, there’s no benefit to doing a bunch of calculations simultaneously and then getting one random output when you could use use an already very fast computer to just do the one calculation you need. However some computations you can sort of work around this to still get useful results. With something like factoring large numbers the only way to do it is to just guess every number and see which ones work. For large enough numbers this can take literally centuries because there’s so many numbers. But with a quantum computer you can use a few tricks to shorten that. You can take advantage of the super position to guess a ton of numbers at once like with any other problem. And then unlike with other problems, you can basically set up logic that cause the wrong answers to sort of cancel each other out before you actually measure it. So instead of getting a random answer out, you get the one answer you actually want. How exactly you do that is a bit beyond an ELI5, but I could try to go into more detail if it’d help. But the TL;DR is that these kinds of guess and check problems (and I’m sure some other specific ones) can be sped up since you can use super position to check a bunch of answers at once and then have the wrong ones cancel each other out. For regular computations it’s just a bigger slower computer that gives you a random output.",
"There is a saying in computer science, nine women can't make a baby in one month. Some tasks simply involve one step after another, there are no shortcuts. Quantum computing is applicable to certain kinds of calculations than can be highly parallelized. Factoring semiprimes is one such calculation. This is a gross oversimplification, but the quantum computer essentially lets you test many possible factors at once instead of one at a time."
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dq5hxd | How do data companies like Verizon work? Where does the data come from? (Sorry if it seems stupid, just something I've been wondering) | Technology | explainlikeimfive | {
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"ELI5: There's the pipes, the water, and the water tanks Users (People, Companies, organizations, educational systems, governments, etc etc) produce the water Verizon is in the business of providing the pipes that move the water wirelessly. Their network ties into the bigger network that's primarily made of fiber runs and server farms. The internet is basically pipes between water tanks and we all contribute to the water in the system. Verizon has water tanks too, but not like the big boys. The water tanks are the servers that hold the data. Governments, and the big tech companies all the way down to personal servers. (Resisted the urge to say \"series of tubes\")"
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dq7aku | Why does sped up audio sound high-pitched and slowed down audio sounds low-pitched? | Technology | explainlikeimfive | {
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"The pitch is just how many vibrations are happening per second. If I play back some audio on my computer at double speed the speakers are being told to vibrate twice as quickly as they would at normal playback speed. Thus every pitch sounds like it's happening at twice the frequency. This is actually an octave. Every octave represents a doubling of the sound's frequency."
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dqa8mh | What is the difference between analog and digital computer components? (i.e. VGA vs. HDMI) | Technology | explainlikeimfive | {
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"In analog voltages take any value between two limits. Eg, if a signal is 0 to 5V, then anything in between is valid. In VGA the range is 0V, which corresponds to complete darkness, to 0.7V which is full brightness. In digital signals you transmit data bit by bit and there's only two valid voltages with some tolerance. Eg, 0 would be 0 to 0.7V and 1 would be 4 to 5V. Any signal that's in spec is as good as any other. What are the practical differences? * VGA doesn't have pixels as such. It has well defined lines, but columns aren't strictly separated. * VGA needs good transmission and circuitry. Back in the VGA days there was such a thing as a video card that produced a better output. Meaning, two video cards, both capable of say 1024x768 and having the same technical capabilities could still be different in that one would look prettier because it would generate more precise voltages and with better timing. * VGA allows for varying color as smoothly as you like, though back in those days computers weren't powerful enough to take good advantage of that. * HDMI has exact pixels. There's no adjustment needed, the monitor can display a pixel perfect image if it's capable (eg, a LCD). * HDMI has exact transmission of data. You can't get better text quality through a better video card or a better cable. If it works, it works, and it's perfect. * HDMI has limited color accuracy. If you're at 8 bits you're limited in how good a gradient you can display."
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dqegeu | How does matchmaking actually work in AAA games? | Technology | explainlikeimfive | {
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"Every player has a number. That number goes up when you win and down when you lose. Typically, when you start playing, you are assigned either 0 or whatever the average number is for the player base. As you win more, your number goes up, so you play against people with higher numbers. Those people also win more, so they should be better. The same is true in the reverse as players get worse. In other words, the game isn’t tracking how “good” you are, it’s tracking how often you win/lose, how well you do in those wins/losses, and who you win/lose against."
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dqf03u | Why do streaming services like Netflix and Hulu seem like they have lower quality on my 24” 2k PC monitor than on my 32” 1080p TV? I use a fire stick for the TV and the websites for my computer. | Technology | explainlikeimfive | {
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"Because they don't natively support that high of a resolution, so you are seeing the effects of scaling. i.e. the highest streaming resolution Hulu and Netflix offers isn't a high enough resolution to look good on your 2k monitor, but looks just like its supposed to on your TV. Trying playing a local video in 1440p resolution or 4k and it will probably look much better."
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dqgp0e | How come music streaming services like Apple Music and Spotify making money doing same thing? | Why will a person subscribe to service which is costlier than other when both of them have almost every music one wants to listen? If one is cheaper than the other then how come both of them has huge number of subscribers? | Technology | explainlikeimfive | {
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"Humans are not, strictly speaking, rational. We will choose \"suboptimal\" choices because we're used to them, they make more sense to us, they're the first thing we found, or they look nicer, or any other of a long list of reasons.",
"It's about the userbase and slight differences in certain features. Like Spotify is well known for its recommendations and playlists features. Apple Music on the other hand has the advantage of the large userbase that apple has. Apple can by default install Apple music on iPhones and most people would choose it because of advertisement. It's similar to like people think no one uses Bing but as Bing is the default search engine on Windows Bing has a lot of users and it makes billions in profits.",
"Each one has a different thing that makes them unique from each other that makes them attractive to different people. I'll list what I think each of these ones are known for. Spotify - Lots of podcasts and playlists Apple Music - Beats 1 radio, the Apple Music/AirPods meme SoundCloud - The most songs and a lot of Indie artists TIDAL (what I use): Lossless audio, very good algorithm for recommending songs It really depends on what each user cares about. I think a lot of people use Spotify or Apple Music because they are the most popular and those are what people know. Edit: A lot of people use the one that's built in, eg. the default search engine on Apple devices is Google so a lot of people stay with Google. Also, a lot of people care about the interface."
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dqhhmq | In simple terms, what is fracking exactly and why is it controversial? | Technology | explainlikeimfive | {
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"Conventional oil deposits consist of oil that exists as an underground pool that's under pressure. To get it out of the ground all you need to do is to drill down into it. Because the pool is under pressure, the oil will naturally flow up to the surface. Once you've extracted enough oil there won't be enough pressure for it to come up on its own, but you can inject water down into it, increasing the pressure and causing more oil to come up. What puts pressure on the oil is that there is a layer of rock sitting above it. Dirt is very dense while oil is not. Because oil is lighter than the surrounding dirt it naturally wants to \"float\" up through the dirt to the surface. But it can't pass through the rock layer above it and so gets trapped. Sometimes the rocks sitting above an oil deposit are semi-permeable to the oil. This means that the oil can enter the rock, but the rock acts like a filter and traps it, preventing it from rising any higher. The way that you extract this oil is that you drill down into the rock and then pump high pressure water into it. This causes the rock to break apart, creating channels that flow out into it. You then pump a solvent into those channels. This solvent pulls the oil out of the rocks and into the channels you created. You can then pump the oil out of those channels and to the surface. The controversy around fracking has three components: The first is in the solvents that are used. The chemical composition of the solvents are considered trade secrets, so nobody knows what they are except for the companies using them and the EPA (in the US). If the rock that's being broken apart is close to an underground aquifer that people are using for drinking water then there is a chance that the solvents can get into that. The second is that the process of injecting high pressure water deep into the ground creates, well, underground pressure which can cause minor earthquakes. Those earthquakes are too small to cause damage to modern buildings, but it is possible for them to damage the kind of very old brickwork buildings you see in some parts of Europe. A significant source of opposition to fracking is more political than it is about the health effects of it. Fracking produces relatively cheap oil, so people who don't want oil consumption to rise oppose it on that ground. Fracking is also a high technology industry - only a handful of US companies have the expertise to do it. Fracking has resulted in US oil production surging to an all time high. This, in turn, has caused the global oil market to be oversupplied. This oversupply is largely to blame for Venezuela's current economic collapse, and is causing serious economic issues in most OPEC countries. As a result, OPEC has put a significant amount of money into anti-fracking lobbying.",
"Fracking is the act of pumping pressurised stream of water into rock to crack it, to allow things like natural gas to flow easily. The obvious drawbacks is that natural gases still pollute the environment to an extent. The water you pump is also contaminated with these emissions and if they leak into the groundwater, people could end up drinking this contaminated water.",
"Because it cracks underground rocks, it can cause minor earth tremors and possibly subsidence. That may cause damage to nearby properties. A recent trial in Britain was halted because reports they it is impossible to predict the frequency of severity of earthquakes. A magnitude 2.9 quake occurred near a trial site in NW England this summer. URL_0 People are also thinking that we should move towards creating more renewable energy sources rather than obtaining additional supplies of fossil fuel to burn and put more CO2 into the atmosphere."
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dql7dj | What’s the process of Dialysis? How does the blood get filtered? | Technology | explainlikeimfive | {
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"The blood passes through tiny straws, which are soaking in a bath, and yucky stuff is pulled out of the blood. It's a brita filter for your blood!",
"Blood is pumped from the body and passed over semi-permeable membranes. When the blood comes into contact the metabolic wastes diffuse from the blood into the filter media."
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dqq2no | Nowadays we have tech that makes typing conversations easier, like in a courtroom setting. How did they accurately capture conversations in olden days though? Wouldnt the natural speed of real conversations be too fast to write down for too long? | I was thinking of old philosophy texts and stuff at first ,but court room stuff probably makes the most sense. Just curious | Technology | explainlikeimfive | {
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"They used stenotype. The stenotype keyboard has far fewer keys than a conventional alphanumeric keyboard. Multiple keys are pressed simultaneously (known as \"chording\" or \"stroking\") to spell out whole syllables, words, and phrases with a single hand motion.",
"They used shorthand, which is a code that uses a number of symbols, short phrases, acronyms, etc. Also, if you look at old attempts at keeping minutes, they did not attempt to record every single word and instead tried to capture the gist of what each person said. [Here is an example,]( URL_0 ) pulled from the records of the US Constitutional convention."
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dquiq0 | How software that runs traffic lights avoids fatal errors while consumer programs crash the time | I'm sure they're better optimized, but if that's it, then why can't it be applied to other software is there something else to it? How do designers ensure that vital programs like the ones that operate traffic lights or electrical grids don't crash or malfunction? | Technology | explainlikeimfive | {
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"They do one comparatively very simple task, all the time, on standardized hardware that's exactly the same for all traffic lights using that software, with few and very well defined inputs, very well defined outputs and if they ever get locked up the hardware running the code has means to detect it and reset. Basically: take everything that applies to general purpose computer environments and it's the opposite.",
"If a consumer computer program crashes, one person gets mildly annoyed and that's about it. If the program controlling a traffic signal crashes, people can get killed in an car accident. So a lot more effort and money is spent verifying that the traffic control program is provably correct and well-tested in all sorts of bad conditions. > then why can't it be applied to other software is there something else to it? It helps that traffic control software runs alone on a single piece of hardware and does a relatively simple job. There are entire classes of bugs that can be avoided by working out every possible state the program can be in and making sure they are all correctly accounted for. It's a similar methodology to what software that controls airplanes and the space shuttle go through. > How do designers ensure that vital programs like the ones that operate traffic lights or electrical grids don't crash or malfunction? An absolutely insane amount of engineering work which costs an insane amount of money. 'Formal verification' is the name of this field in computer science. Consumer products simply can't afford to be that rigorous and still be sold at a price people would pay. But if your software is used in situations where it absolutely cannot be allowed to fail there is no other option.",
"In addition to the answers already here, many have hardware interlocks that only allow one set to be green at a time.",
"Imagine there were no computers and you had to explain to a human being how to emulate one of these consumer programs. Let's say it's words with friends on an iPhone. You have to tell them all the what-ifs about what usernames are allowed, a dictionary of words, how to handle low battery or network issues, multiple chat messages coming in at the same time, multiple apple devices, older operating systems, etc. Thousands of combinations of variables that you need to make sure this person (program) can account for. Now imagine you're telling a traffic controller how to control an intersection. You give some basic rules (can't have multiple intersecting flows of traffic have a green light at the same time), some advanced rules (leave the light on longer if there are more cars waiting), and tell them that if all else fails, just start blinking red and become stop sign. This is a much more manageable task. The number of inputs for a stop light are very small compared to most apps, and the number of things it needs to do are very limited. It's much easier to write code for this sort of super-focused isolated environment.",
"No keyboard. A traffic light does not get random input or flaky downloaded games installed. A simple program on an isolated computer will do the same thing forever unless there is a hardware problem.",
"Compared to most other software traffic light control is pretty fucking simple... I'm a firmware engineer, the RTOS's I design are several million lines of code... I would love to be paid what I make to write simplistic things like traffic light control code...",
"At a most basic level, digital hardware and software are as close to deterministic as we know how to get. In other words, for a given set of starting conditions and inputs, the outputs will always be the same. It's just that in modern, general-purpose computers and software, there are so many interacting bits and pieces of code that all kinds of little mistakes or assumptions in the writing of that code can lead to unexpected results (bugs and crashes). It is entirely possible to design software that is very reliable - and in some cases even \"provably correct\". In fact, correctness proofs was a hot topic in CS for a while. It's just that actually doing bullet-proof systems of software is very hard, and requires great training and discipline from teams of many, many people. So it rarely happens, except when really needed, like in space shuttle flight control software, for example. 99.9% of software design and production makes some level of compromise to reduce the time and effort to create and release that software. In a traffic system the hardware and software can be simple enough to be programmed \"correctly\" to a high degree of certainty, even with reasonable costs. That is not true for most systems.",
"Because nobody shows up in the programmers office halfway through the project and says \"Brad in Marketing told the customer we could add a purple light, so just slip that in somewhere, k?\" Seriously. Most software projects are plagued by a series of constantly changing requirements that have little or no thought put into how they will effect the product in the long term.",
"They fail all the time, when they do, they go into a failsafe mode, usually flashing red in all directions. When software is tested, it isn't just a matter of whether it works or not, it is a matter of degree. A video game that fails to start one time in a hundred might be annoying, but that is something a user can live with, a developer might decide their limited time is best spent elsewhere. A traffic signal controller that fails that often is a no-go, they will fix that bug before doing anything else, and test to ensure its failure rate is something like one in a million. This is a class of programming called real-time systems, using in factories, life support systems, airplane, cars, financial transactions, and any system where a program just can't give up when it fails or get slow when things get slow. Part of real-time is keeping things simpler and testing the hell out of them, and part is failing gracefully and reverting to some safe, predictable default behavior when the unexpected happens. If the computer is supposed to slow down the engine if it gets too hot, and suddenly isn't getting any temperature data, it should slow the engine down to a safe level until the situation is resolved.",
"Any normal computer is tasked with listening to the keyboard, figuring out how the mouse pointer is supposed to move, light up and dim down the monitor depending on how dark it is outside, and all kinds of other shit that you really don't need in a traffic light controller. It's a whole lot easier to make a computer stable if the set of instructions it has is a list of behaviour that is so short that you can somewhat easily understand it all. The traffic light controller is *just* good at traffic lights. It's incapable of nearly anything else you can think of. It understands the concept of red, yellow and green lights. It understands the buttons for pedestrian requests and it understands the sensors that helps it detect and count cars. But it doesn't understand shit more than that, which means that it's reasonably easy to maintain not only the equipment in the intersection but also reasonably easy to maintain the software that controls it all. Think about it like this for a bit, *Sensor 5 says a magnetic signature just passed* Uh, right. Sensor 5. WHAT DO I DO? Oh, I know. I look at the \"sensor five scheme\" and find out what that says. Oh. Sensor five means CAR APPROACHING FROM NORTH. I'll flag north as having a car inbound, then. *Sensor 4 says a magnetic signature is stationary* Uh. Right. Sensor 4. WHAT DO I DO? Oh. I know. I look at the *sensor four scheme* and find out what it says. Oh. Sensor four means CAR FROM NORTH WANTS TO TURN LEFT. I'll flag north as having car waiting to turn left, then. THIS IS SO EXCITING. I LOVE THIS JOB. How many cars do I have waiting? Oh, wait. North has a car. It approached 5 seconds ago and is waiting to turn left since 1 second ago. WHAT DO I DO? Oh. I know this on too! I have a look in the \"car from north wants to turn left scheme\" and find out what it says. It says \"flip all the lights to red, wait 10 seconds, then flip NORTH TURNING LEFT to green\". Yay. This is AWESOME. I TOTALLY LOVE DOING THAT. Heeeeeere we gooooo! Yo, north leftie, can you do that awesome turn-off-the-red-blink-yellow-keep-green-on-thing for me? Awesome! Thank you. That worked great. I've done that for 15 seconds now, and fucking hate left turners. And he should totally be out of the intersection by now anyway, I'll flip all back to red again. You, north leftie, you go red NOOOOOOW! ... Now, you can complicate this all a lot. You can put in sensors that are able to differentiate between cars and trucks. (because trucks are heavy and has a longer stop distance than cars. Flipping the light to red right in front of them when they can no longer safely stop is not only a dick move, it has no technical bearing; you will end up with a truck in the middle of the intersection that the controller didn't expect to have there.) You can put in so many sensors that you can tell if there is one or many cars waiting in a lane. (because, uh, several cars waiting means that the off ramp that feeds that lane may be getting full. Let's not clog the highway!) You can use the sensors to count cars while they are in motion. (it may be nice to know how many cars you will force to stop at the intersection if you flip to red right now, because if they are more than five, one of them may be forced to stop on the crossing tram tracks?) You can differentiate between moving and stationary cars. (A stationary car is waiting. His patience is already running up. A moving car is still not really a problem.) You can have them trigger timers so that you know exactly how long someone has been waiting at a red light without being served. (there has been studies on traffic behaviour; How long do people wait on a red light that is never flipping over to green in the middle of the night? About three minutes. After that, we all say *\"this bloody thing is broken. Let's look real careful and slowly cross this intersection anyway.\"* And from that you can derive the reasoning that if you force someone to wait for more than three minutes, you will gradually make locals stop respecting the light. You need to pay attention to how long you force anyone to stop.) You can put sensors in the middle of the intersection so that you can detect when the intersection is clogged and there is no use letting cars into it any more. (kind of self explanatory. EMPTY the intersection, THEN let in new vehicles.) You can detect when cars actually exit the intersection to establish where the cars you let in actually leave. Because if you know, you can tell the controller further down the road what kind of shit is coming his way. *(and modern controllers tend to do this with a camera and a small computer that analyses the picture instead of sensors in the pavement.)* The whole idea is that if the controller has no input what so ever, all the lights are red. When a sensor says that a car is approaching and has a certain behaviour, it flips over to a set of instructions that it follows until that set of instructions is depleted, and then it goes back to red again. And waits for something new to happen that it has to react to. Most instructions are sort of expressed as \"keep light green for at least 15 seconds, reset timer every time a new car approaches. But if a car approaches that wants to move in a direction that interferes with this green light, don't let them wait more than 60 seconds if we can count to more than five cars in the intersection and no more than 20 seconds if there are less than five cars in the intersection.\" And you can put up sensors that detect the flashing lights of emergency vehicles. An intersection that knows what it's doing flips the entire intersection to red, and then it flips ALL THE LANES to green from the direction the ambulance is coming from so that the ambulance gets free access to any lane and any direction. And you can have dedicated bus lanes, where all the buses have a radio transponder so that the intersection only reacts when there is an actual bus in the lane, and not just a large truck. And so on and so on. But. It's still the same type of thinking. *Sensor X reports behaviour Y*. \"Uh, right. I have to look that up. What am I supposed to do now? Oh. It's a pedestrian? Crossing 8 lanes? I better turn them all off, then.\" And, mind you, a smart programmer also writes in behaviours that fit together. Because, technically speaking, you can allow two opposing left-turns at the same time in the intersection. They are not supposed to interfere with each other. And you can write in four right-turns at the same time. They are not interfering with each other. And while you let a pedestrian across, you can also serve two right-turns in the other half of the intersection. But. Compared to a personal computer all that it does all the time to function, it's still just a very, very short list of capabilities and a very short list of behaviour. And that is what makes it so stable. It's not really doing that much, and since it isn't, it's relatively easy to ensure that it does all it's supposed to do in a way that is proper and reliable."
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dqvfok | When referring to hashes in cryptography- What are they and why are they irreversible? | Technology | explainlikeimfive | {
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"A hash is a unique way to take some plaintext and reduce it down to a unique, (typically) much smaller value. Kind of like running meat through a grinder. Although the resulting hash is unique (actually, *nearly* unique) to that particular plaintext, a great deal of information is lost in the process. You simply can't recover what isn't there. Kind of like trying to re-create a steak from the ground meat. The only way to do it would be to take *every possible* plaintext and run it through the same hash function and see if the result matches. That offers some practical difficulties, to say the least.",
"They are irreversible in the sense more than one value can make to the same hash value. A simple hash function might be \"divide by 9 and take the remainder\", a technique commonly used for checksums. If I told you the hash was 4, you'd have no idea whether the original number was 13 or 76 or 538,099,475. Also, the hashing algorithm is designed in such a way it is mathematically difficult to start with a hash and find a number that maps to it. Division takes more work than multiplication, taking a root takes more work than raising a number to power, despite those being inverse operations. A good hashing algorithm takes advantage of similar asymmetries. Finally, practically speaking, hashes **are** reversible. It is really hard, as per the second reason. The first reason often doesn't hold because you can often make reasonable guesses what the original value looked like. There might be an infinite number of values that map to a given hash, but if you can assume that value is 12 or fewer alphanumeric characters with punctuation, there very well might only be one match."
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dqyqz0 | How much flying human pilots in planes actually do and how much is autopilot? And,if autopiloting would do all the work,would that mean we wouldn't need human pilots at all? | Technology | explainlikeimfive | {
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"If the runway is equipped with a suitable ILS (Instrument Landing System) which helps guide the plane/pilot down, it is possible for the autopilot to land the plane itself as well. It's not always used, but if it is then the autopilot would likely be in control of the plane from a few moments after take-off all the way to the moment all the wheels are on the ground. Humans are responsible for everything else, from the outside safety inspection of the plane to starting the engines, taxiing the airplane to the runway and taking off. That said, the autopilots don't handle failures very well. If the instruments feeding information to them stop working or any of their consistency tests fail, they produce an alarm and relinquish control of the plane. For the auto-land thing above (at least on some models of airplane) BOTH autopilots need to be activated and if they start disagreeing about what to do then auto-land is aborted. When in doubt, the human is the last line of defence against malfunctions. Also robots can't talk to Air Traffic Control yet. :)",
"Pilots do the taxiing, take off and landing, where most accidents happen. They can turn on autopilot once they're in the air and deactivate it before they land. Autopilots can fail. See: MCAS. If you leave autopilot alone, who'll fix problems when it fails or becomes faulty?",
"Autopilot can handle 99% of flying. However, that 1% is the difference between landing safely and catering in a field, so we will never completely remove pilots from the cockpit."
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dqzsif | How does WiFi not get confused? | If WiFi signals are sent using the same radiation, how can multiple devices send/receive data on the same network at the same time without packets getting sent to the wrong device or interfering with each other? | Technology | explainlikeimfive | {
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"Each device has a unique identifier called a MAC address. Devices on the same wifi could theoretically receive data from all the other ones, but they just ignore data packets that are not meant for them (don't have the right MAC address). It's a bit like sharing a mailbox with other people. You only open the letters that have your name on them and leave the others alone.",
"Each device transmits data in short packets, each packet lasting about a millionth of a second. So most of them don't overlap. In case of an overlap, sometimes both get garbled. In this case each device waits a random small delay, then tries again.",
"Short answer: They don't really Long Answer: Your router/access point can actually only talk to 1 device at a time (some newer ones have multiple radios that can do 2 or 3 by using separate channels). It essentially plays a game of round robin with all your devices, and gives a little bit of time to each device. It dynamically decides how much time to spend with each device based on how much bandwidth the device is using. If something isn't using any bandwidth at all, like a phone that's in your pocket, it spends very little time and just checks in every second or so. Devices that are downloading big files, it allocates more time to. There are also various identifiers in the data being sent so devices know what is and isn't for them."
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dr9kqt | How do you treat injuries like the one Andre Gomes suffered from today? | Technology | explainlikeimfive | {
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"Sports injuries tend to be assessed in this order: First the team's trainer or doctor (a medical professional who specializes in sports injuries) will try to determine if it is a \"soft tissue injury\" (a sprain or a strain) or worse, and call over the emergency responders (EMTs or paramedics) if needed. The emergency responders will check for excessive bleeding and control it with a tourniquet if necessary. They will check CMS - Circulation (pulse), Motor (can you wiggle your toes?) and Sensation (can you feel me touching your foot?) This will tell them if there is a blood flow or nerve problem. They either try to reposition the foot into its \"anatomical position\" (where it is supposed to be in line with the leg) and splint it or leave it as they found it with lots of padding. Protocol usually dictates that they only attempt to reposition ONE time, as manipulating an injury too much can cause further damage. But if achieved, getting the foot back into anatomical position can help alleviate pain and restore bloodflow. This will all happen immediately and simultaneously while they wheel the player off the field to transport him to a hospital specializing in trauma surgery. During transport he will get pain medications through IV (intravenous / in the vein) tube that can be used in the hospital for administering more meds and fluids. Once at the hospital, the injury will be X-rayed and the patient will go to trauma surgery right away, especially if there is a bleeding or circulation issue, but further repairs may be delayed waiting for a specialist orthopaedic surgeon. the bones will be held together with pins, tendons and ligaments can be reattached but they do not regrow or repair like bones. The patient will then require physical therapy that will probably involve the team's trainer and sports physician again.",
"I saw it live, it was horrendous. But usually surgery to reposition the bones, insert rods/plates/screws to hold the bones together, remove threatening bone pieces and the rest is left to the body to heal itself over a long period of time. I’m sure sure if he will recover well enough to play again."
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drjllj | How did the different sides in past wars (esp WW1 and WW2) communicate and collaborate with each other so effectively when organizing their offense and defense in different countries around the world? It sounds like a logistical nightmare, even with today's communication devices. | Technology | explainlikeimfive | {
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"Wars are not planned \"on the fly\", even today. People sit down at desks in the War Department and write out plans, wargame those plans, and then send them out. Commanders in the field tailor the plan to the forces on the ground, and communicate them to their subordinates. This used to be on paper, then on coded message, then in coded radio messages.",
"There were and are issues with that. But its important to remember that's the reason for the chain of command. The big guys at the top dealt with the biggest picture while the lower down you go the smaller the piece but the more details. Eisenhower didnt concern himself with what individual battalions or companies were doing.",
"Even at the time of WW1 there were multiple transoceanic telegraph cables allowing you to send telegrams all over the world. There were also air mail carrying smaller packages over great distances. You did also have radio which allowed \"mobile\" communications with ships and places without telegraph but the limited encryption technology made this form of communication liable for interception. The geographical position of the central powers did cause some problems though and there were a few instances when their communications got intercepted. For instance when the High Seas Fleet set sail the British intercepted their radio transmissions immediatly and set out the Grand Fleet to meet them at Jutland where they managed to see them off. In addition the Germans had to send a telegram via Sweeden, Great Britain and USA to reach Mexico when they asked them to join the war on their side. The telegram was intercepted at multiple places causing the US to join the war instead of Mexico. In WW2 there were not as many improvements in communications from WW1. Mail planes were able to go faster, further and carry more cargo. There were even more telegraph cables available. And now there were sufficient encryption to be able to send encrypted radio messages although both the Germans and the Japanese had their encryption broken by the allies during the course of the war. It was for instance possible for airplanes to dart inn and around enemy airspace when delivering mail and they might even carry diplomats. See for example the \"Stockholm express\" route carrying gold, passengers and ball bearings in addition to mail between Great Britain and Sweeden through German occupied territory. It was also easier for diplomats to meet in person due to the better airplanes and also faster ships which even allowed the heads of state to meet in conferances to plan the war in person instead of having to do the discussions through telegraph and proxy diplomats.",
"Worth pointing out that the Axis Powers did not communicate or collaborate very well at all. Germany's plans were repeatedly thwarted by the Italians opening other fronts then losing. Japan barely helped them at all. They did nothing to divert Soviet attention away from Europe and brought *another* super power into the war (which they couldn't beat on their own and couldn't call on allies to help) Yes, the Allied powers worked together very effectively but, taken into context, they could hardly do worse than the Axis if they tried."
],
"score": [
13,
9,
4,
3
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drlov7 | How does dial-up internet work and what makes modern internet technology better than dial-up? | I mean, I remember the days of AOL. And I know you had some sort of phone connection required to actually connect to the internet and be able to browse the web. But I don't exactly know the nitty gritty specifics of how it all worked and how we use modern internet technologies today. | Technology | explainlikeimfive | {
"a_id": [
"f6jb233",
"f6jsiyd"
],
"text": [
"Your modem literally started a phone call to a set number that had the ISP's hardware listening, then started whistling digital data in the audio frequency range. This is why the internet went down if somebody in the house picked up the phone in some setups. The audio frequency range can only support a painfully slow rate of data transfer, so later on the digital data got decoupled from the phone frequencies (often still on the same wire but at 1000 times larger frequencies so the signals are easy to separate from each other at the endpoints) and the phone numbers system.",
"Imagine a normal conversation on the phone in English \"how are you doing. good ,how about you\". computers don't talk in English they use binary \"0110100001101001\" now pick a tone, any tone that you can hear to represent both 1 and 0. these are the noises you can hear on a dial up hone connection. the reason we use tones we can hear like that is because the phone system only supported a few frequencies that you could hear (this is why phone calls sound so bad) broadband expanded this phone system so you could use much higher frequencies that we couldn't hear on the phone it also uses more frequencies so we can send more of those 1 and 0 noises at the same time. Nowadays we use even better technology like fiber optic cable which basically does the same thing except it uses light instead of electricity. and because of its higher frequency we can send more 1s and 0s in a shorter amount of time on many more frequencies at the same time."
],
"score": [
3,
3
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drocpq | How do big companies like Amazon that have customer support Twitter accounts handle all the tweets that they get by the minute? | Technology | explainlikeimfive | {
"a_id": [
"f6k5kg3",
"f6jzsr1",
"f6k39v6"
],
"text": [
"My fiance does this for a living for one of the huuuuge companies (she does mostly Instagram, but the software does Facebook, Twitter, insta, YouTube). Her company runs CS phone banks and email services which they contract with corps to handle on their behalf. Social media team's are considered the advanced positions since they have more latitude with responses. Basically there is a team that gets the incoming messages in a program, and her team's full time job is to tag each tweet, and send an appropriate canned (usually) response. Different brands have different \"voices\". They have authority to hand out coupons as apologies and such to a certain extent, have to do medical documentation for medication complaints, and refer to specialists when needed. Mostly it's just fun feedback (i.e. \" your baby is soooo cute!\" or \"sorry to hear that, here is a coupon for a new item since that one was faulty\"). She has a video conference with each brands marketing team on a regular basis, and works from home on her laptop. Pay is in the teens per hour.",
"There are services (Hootsuite, Freshdesk, etc.) that are designed for team-based usage of social media accounts. Generally, this means response-needed tweets are placed into queues that are handled by individual agents, much like how calls in a call center are routed to open representatives.",
"Nah, you get an API key and plug it into your CRM etc. software. People as big as Amazon write their own stuff for this, or integrate massive programs with each other. Then you can load-balance, distribute to all your customer service staff, track and record all responses etc. Hell, even most people who tweet a lot or have a small business have an API key and plug it into one of those bits of software that duplicates their posts to Facebook, Twitter, etc."
],
"score": [
18,
6,
3
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"text_urls": [
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} | [
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|
drto7p | How can a single pixel on a TV screen change to so many different colors? | Technology | explainlikeimfive | {
"a_id": [
"f6l1gyo",
"f6l3xcn"
],
"text": [
"You remember mixing paint colours when you were a kid? A single pixel is made up of a tiny blue light, a tiny red light, and a tiny green light. It can be any colour just by controlling how strong each of these colours shines inside it. More modern screens (e.g., Liquid Crystal Display) have fancier technology but let’s stick to ELI5.",
"Your eye have 3 types of cone cell that detect light color. One type is most sensitive to blue light, one to green light and one to red light . So any color you can see is a combination of signal from the three types of cones. A monitor have red green and blue sub pixel where each primary stimulate only on cone type. By changing the amount light each sub pixel emit can use get any response from the eye and see any possible color. So by exploiting how the human eye work you can produce any color with light on only 3 colors. It is a bit simplified explanation and a RGB monitor can't show all colors you can see with you naked eye. I suggest looking at [Technology Connections - The Weird World in RGB]( URL_0 ) for entertaining explanation of color vision and RGB work and the limitations."
],
"score": [
13,
4
],
"text_urls": [
[],
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"https://www.youtube.com/watch?v=uYbdx4I7STg"
]
]
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|
drvexl | How do laser-dependent devices work? (etc. infrared thermometers and radar guns) | Technology | explainlikeimfive | {
"a_id": [
"f6lbmjy"
],
"text": [
"The laser only helps the operator see where the device is pointing. This is like a laser sight mounted on a gun. Infrared thermometers capture how \"bright\" a surface is in the infrared spectrum with a lens and detector. The hotter something is, the more infrared light is released. It converts this infrared brightness to a temperature. Radar guns shoot out radar waves and record what comes back. Due to the Doppler effect, things moving towards the gun will have higher frequency waves and going away will have lower frequency waves. This is the same effect where the pitch of an emergency vehicle siren increases when it approaches but decreases when it drives away. Based on this frequency difference, the radar can calculate the speed of the object it is pointing at."
],
"score": [
3
],
"text_urls": [
[]
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} | [
"url"
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"url"
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|
drzm0o | Why can't web browsers block lightbox-style popups? | Browsers killed popups and popunders years ago, but advertisers just moved to those popups-that-aren't-technically-popups. Adblockers and browsers seem unable to stop them unless you manually pick out the code. Why can't we just kill them off like we did with popups and autoplay videos? It seems like we could use AI to say "did something just appear that's blocking the main content of this page? If so, kill it". | Technology | explainlikeimfive | {
"a_id": [
"f6lyp64",
"f6m3pja"
],
"text": [
"Popups, popunders, and autoplay videos are all very specific actions. The site's code has to ask the browser to make a new window or start playing the video, and the browser can easily respond to that. Lightboxes are different, they're just another element on the page. The actions that create a lightbox are no different than creating a colored box or button. In addition, there are many different ways this can be done that end up creating the same effect. It's certainly possible to detect some or all of these cases, but it's nowhere near as straightforward as popups or videos.",
"The browser has no universal way of knowing what the \"main content of a page\" is. That's ultimately a human interface concept, not a technical one. It could try, but that would risk breaking some pages."
],
"score": [
8,
3
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
drzmzh | How Wikipedia website works, Who can edit or create articles. Do author need to attach source or proof with articles? How we can trust everything is right and trustworthy. | Technology | explainlikeimfive | {
"a_id": [
"f6ly7xh"
],
"text": [
"Anyone can edit or create any page. Wikipedia has three main rules: 1) a page must be written from a neutral point of view, 2) all claims and quotations must be verified by a reliable source outside of Wikipedia, and 3) everything in the page must be attributable to an outside source (you're not allowed to write original research). If you're trying to decide whether a particular page is trustworthy, ask yourself: Is the writing biased, or neutral? Does it give sources for its claims, or just make claims without proof? Is the page referencing research done somewhere else, or is the page making conclusions on its own? There is no guarantee that a page is correct and trustworthy - but if you come across something that you believe is incorrect, you can edit it and fix it!"
],
"score": [
10
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
|
drzvww | What is Virtual Reality and Augmented Reality? | Technology | explainlikeimfive | {
"a_id": [
"f6lzzzr",
"f6m017l"
],
"text": [
"Virtual reality is where the user interacts with a fully virtual space such as a game world. Augmented reality is where a virtual overlay is added to the real world, such as an Ipad app that recognizes objects and displays information about them when the camera is pointed at the object.",
"Virtual Reality, is generally going to be something that immerses you 'in another world', most commonly by changing what you see and hear, but still reacting to the actions of your body in some way, giving you the ability to interact with what you see and hear. Augmented Reality, is like putting a lens over the world you are interacting with, allowing you to see and react with the physical world differently. The goal here isn't to take you somewhere else, but enhance your interaction with your surroundings."
],
"score": [
4,
3
],
"text_urls": [
[],
[]
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} | [
"url"
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|
ds1ee8 | If I'm paying for 100mbs download speed why does it take longer than 10 seconds to DL 1 gigabyte | Technology | explainlikeimfive | {
"a_id": [
"f6mcy02"
],
"text": [
"You're paying for megabits(Mb) per second rather than megabytes(MB) . Megabits are a unit for measuring download speed, but it's never made clear in service provider advertising. A byte is eight times bigger than a bit, so your actual download speed is going to be a lot worse than you expect."
],
"score": [
4
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
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|
ds39fz | How do hidden photo apps work? Where are the photos actually "hidden?" | I can't find them anywhere else at all on my phone, which is a good thing, but I cannot figure out where they actually "go" aside from into the app. | Technology | explainlikeimfive | {
"a_id": [
"f6mtuer"
],
"text": [
"There are many ways todo so. But first a little explnation of how your phone memory work. To store a file youre phone keep a table of where in the memory each file is the name and exetension. The extension tell the system what kind of file that is (since in the phone memory everything is nor 0 nor 1) so if the phone see .png .jpg .img or so it knows that he must read it as a picture and not a song for instance. The app probably just store them with an extension that tell the OS \"open this file with this app\" and the app know that this extension is a hidden photo but not the rest of your phone who just know the common name like .jpg .png etc"
],
"score": [
9
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
ds4223 | Why do vehicles make those pinging and popping sounds when you turn them off after driving for a while? | Technology | explainlikeimfive | {
"a_id": [
"f6mz2iq",
"f6mz9ur"
],
"text": [
"Vehicles have lots of moving and tight-fitting parts, those parts heat up (expand) due to friction as you drive. When you stop and turn the car off, parts cool (at different rates due to differing materials and such). As they cool they shrink again, the popping happens when two parts snug against each other cool and reach a point where the static friction points (the specific points where the parts touch) slide past each other, creating sound.",
"When metal gets hot it expands, its not that much but it does get bigger. Then when it cools off it shrinks, different metals cool and and go back to their normal size at different rates. The different types are next to each other and cool at deffent rates so the rubbing and settling are what cause those noises."
],
"score": [
32,
3
],
"text_urls": [
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} | [
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|
ds4dod | portable USB-C chargers for laptops, Power Delivery (PD) | I'm trying to buy power options for my new used laptop and it seems like there was a new standard put into place that I'm not sure of. My laptop can take 65W for fast charge and comes with a MacBook charger (my laptop is not a macbook but apparently it works...?), I also have a Nintendo Switch and I'll probably get a USB-C phone sometime in the future. Do they all work with the same devices? What is PD? | Technology | explainlikeimfive | {
"a_id": [
"f6n8hi7"
],
"text": [
"USB PD is an official spec for USB chargers that lets the charger announce the power levels it supports and then the device can request a specific power level. Importantly, it allows these to select much higher voltages to get much power, to the point that you can push enough power to power a laptop. As for phones and such, yes, a USB PD devices work with all USB devices for charging, even those that do not use USB PD (but you won't get quick charging because the default, that unsupported devices get is 2.5W). USB-C is actually the name of the connector on your phone (it's reversible) and has nothing to do with USB PD. Though in practice most USB-C devices support USB PD since USB PD is older than USB-C. However, a USB-C USB PD cell phone charger probably can't supply enough power for a laptop to run off of, if you connect them, I don't know if the laptop will give you an error or just go with the inadequate power. A big laptop rated USB PD power supply will have no issue powering a laptop or a phone."
],
"score": [
4
],
"text_urls": [
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} | [
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