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byqxf4 | Why do graphics cards use GDDR6 RAM but RAM in our phones, PCs, etc are DDR4? | Technology | explainlikeimfive | {
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"After GDDR4/DDR3, GDDR spit off to be a different style of RAM with different goals. Graphics memory requires obscenely high throughput, but some latency is acceptable as they're only looking to draw a frame every few milliseconds or so and all graphical tasks can go in parallel so the GPU tends to pull large chunks of data which makes the higher latency hurt less. Your CPU needs low latency memory because it is often waiting for something to come out of memory so it can keep calculating. Its often looking for a single chunk of data which is where latency hurts you the most. You don't want to use GDDR6 as main memory as it will hurt the CPU's performance, and you don't want to use DDR4 as GPU RAM as it'll limit the GPU's performance. This is why we split them apart after GDDR4 which was DDR3 based, so each computing device could have the best memory for its workload."
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bys9n1 | Why do some electronic screens look weird at certain angles? | Technology | explainlikeimfive | {
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"Most screens these days are Liquid Crystal Displays (LCD). It works by shining a light through a filter that only allows light that is twisted horizontally through. (Polarising Filter) Then there's a liquid crystal that either twists it until it's vertical or lets it through unchanged. Then there's another Filter that only lets through vertically twisted light. When you view it from any direction except ahead, all this filtering causes the light to get filtered out or get filtered out wrong."
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byv4pr | How do cryptographic hashing functions work? | To give you some context, I attempted to build a hashing function myself for fun and the result was quite average even after I tried to extract all possible information from any given input string. After doing some research on the currently used cryptographic hashing functions, the methods used in the source code seemed really confusing and incoherent. Is there some logic to this or do they just try and mix it up as much as they can? I understand the basic principle behind these functions and their uses, however how are these functions able to reduce collision frequencies so dramatically? Do functions like MD5 and SHA have the same underlying idea and are build on previous functions or do they have their methods of hashing? | Technology | explainlikeimfive | {
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"I don't know how to explain the alghoritm and proof in a simple way, but the method used by the hash functions of MD5, and all SHAs is the Merkle-Damgard construction."
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byw1ix | Why do businesses save their computer files with underscores in the names rather than spaces? | Technology | explainlikeimfive | {
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"In the terminal, spaces are used to separate command line options. If you have a space in a file name, you can't use it as an option without putting it in quotes. The terminal is a place where you can type commands to make the computer do stuff. Some people, like [Strong Bad]( URL_0 ), find this easier than using a mouse. EDIT: Changed \"parameters\" to \"options\", to make it eaiser to understand. Added a paragraph about the terminal.",
"Many file systems can not accept spaces in a file name. Putting an underscore helps to create a space and thus delineate and separate words for easier reading. EDIT: After reading the comments I realize I didn’t express myself correctly. Yeah, unless it’s 1992 and you’re using DOS, you can have spaces in the file name. However there are databases that don’t like it, some older individual programs and of course%20this%20awesome%20problem.",
"Outside of all of the programming talk, spaces can also break hyperlinks. If I send a hyperlink that contains spaces, the hyperlink ends at the first space. So If I send [ URL_1 ]( URL_0 ) like i'm five/, you can see the result.",
"Spaces are separators in some contexts, so including spaces in the fllename requires special care to distinguish between a filename with a space and a filename and then some other argument. [basejester@toshiba ~]$ mkdir \"Vacation Pictures\" [basejester@toshiba ~]$ cd Vacation Pictures bash: cd: too many arguments [basejester@toshiba ~]$ cd Vacation\\ Pictures/ The backslash in bash \"escapes\" the space to make this work. It's almost always possible to work around the space with some convention like this, but we have to remember to do it in exactly the way the system we're using expects. This is less important to people than it once was, but the grey-beards have at least once been significantly foiled by a filename with a space in some script, so we tend to avoid it.",
"Inertia and compatibility. While currently (and for quite some years already) all modern OS'es and software have no problems with spaces in file names, some older software does have such problems. Businesses are much more likely than consumers to have some ancient software running somewhere that has this limitation and would break on such files. So look at this from a \"process perspective\": 1) it's difficult to make a policy that specifies where exactly spaces aren't okay and to effectively train people on it. It's much simpler to mandate a policy of \"just use underscores everywhere\" after you have one incident where spaces caused problems. 2) policy has substantial inertia. It's possible that the last system that had such issues was decommissioned five years ago, but nobody reviewed that policy because it would require time to check, and if it turned out that there still is something somewhere, the person suggesting the policy change would get some blame, so nobody does that.",
"Another reason is that Internet browsers won't display spaces in file names or URLs so they substitute the hex equivalent. For example if you have a web page that you want to name \"My Favorite Recipes.html\" then it will be displayed as \"My%20Favorite%20Recipes.html\" , which is pretty ugly and hard to remember. Much better to name it \"My_Favorite_Recipes.html\". Same thing with photographs, PDFs, or any file name that may be displayed in the browser address line - \"My Chocolate Cake.jpg\" would be \"My%20Chocolate%20Cake.jpg\".",
"Because programs mostly need a special syntax for filenames with spaces or just don't accept them at all. In many programming languages spaces are used as a separator between commands and referencing such a filename in a command line is a big hassle. Apart from spaces, other special characters like * . ” / \\ [ ] : ; | = , < ? > & $ # ! ‘ { } ( ) are not allowed because they are part of the language itself and would confuse the computer. Underscores on the other hand are allowed because they are not used for any kind of syntax or commands and still look nice in a filename.",
"Generally, using fewer special characters in file names reduces risks associated with bugs in applications. Risks are different on various abstraction levels involved in working with files: - OS - Any file name that is permitted on this system will work - Network drives, Email - Bugs are possible, depending on the particular implementation - Enterprise databases, corporate document stores, accounting software - This is where all the bugs are! The code for those is often neglected, so every corner case has it's own bunch of bugs. The rule of thumb here is: if you have to use custom software that isn't very well tested and supported, limit the feature set you use to the minimum.",
"While there have been many comments explaining the technical historical reasons, there is one still very relevant reason today: It's a name for refering to a thing (a file), but it's usually built from the general vocabulary, so having spaces in it makes it hard to delineate and identify. Imagine if people were named \"refrigerator temperature protocol\" or something. And imagine reading that sentence without quotes. That's why naming things with what is essentially a word is useful: You can tell it's a name, where it starts, and where it ends, when it's used in a context that doesn't make that obvious anyway. For proper names, we capitalize the first letter of every constituent word, and we use a separate vocabulary (\"proper names\") so you can figure out what is being talked about. With files, you want the names to be descriptive rather than just an identifier (like, calling your files Maria and Jacob), so that isn't an option, so you instead want to have another convention that makes them easy to refer to unambiguously.",
"I learned computing on Windows 3.1 and only noticed a couple of years ago that these days you CAN put a space in a file name. Wasn't possible when people my age (46) learned in middle/high school/college.",
"Compatibility issues. You expect everyone to be able to catalog and read the files regardless what computer system they are using. It is much cheaper to say to all your employees to use underscores than to have someone rename everything later in case it becomes necessary.",
"What happens if you use a - instead of a _ ?",
"As far as the web is concerned it used tio be the case the some browsers would have difficulty with URL's with spaces in, so it could be a hangover from that.",
"Purely for safety. Spaces can cause problems in some systems. BetterToWriteLikeThis or_like_this.",
"ELI5: Spaces in filenames are like riding a tricycle with a flat spot on one of the wheels. You can still ride it, but you'll have a bumpy ride. Modern filesystems allow spaces in filenames, but for historical reasons you'll have an easier time working with files if you avoid spaces.",
"I do it mostly because I do some web work and having underscores in filenames (like images or html pages) avoids the ugly URL_0 Spaces get converted to their ASCII equivalent which is %20",
"Back when I started working with pcs and this was 1993, you couldn’t have spaces in filemames. But another reason is sorting, especially in file names that use dates, so I work in sales and I do a sales report in excel every Monday and a plan one too. Sales wk 14th June 2019 Sales wk_14th_june_2019 They sort differently",
"Hey I can kinda answer this one! The place I work for uses SharePoint for all of our files, so I'm basing my answer purely off that. If you don't know, basically with SharePoint I can upload a word document, let's say it's called 'My File', and then I can send that to my coworkers. If you were to have a file called \"My_File\", then when you send that as a URL to someone it would be \" URL_1 \" . However, if you had a file called \"My File\", and you send that as a URL, it would appear as \" URL_0 \". So obviously, with a name like \"My File\" it's not a huge deal, but when you have a file called \"2019 First Quarter Financial Reports from Department X\" you start ending up with a lot of mess. Hope this helps!",
"Web designer here. Spaces do funky stuff in urls and Jacqueline keeps calling me about it. Just stop using spaces Jacqueline, it's not that's hard.",
"Back in the 90s we were running an AIX system back end with samba sharing. Windows PCs with shared network drive. A Unix system admin then told me he wouldn't be able to to restore any file from the backup tapes if there were spaces in the file name. Habits die hard."
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byxb58 | Why do lithium ion batteries in a laptops charge to 100% then uses adaptor power while batteries on phone don't? | Technology | explainlikeimfive | {
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"Two reasons, the practical being the most important case though Practical: There is basically zero demand for people to run a mobile phone, without a battery, in a fixed location. This is an exceptionally obscure condition, as such, designing a phone that would be in a case with no battery and get power direct is never gonna happen. If people did use phones this way (and they don't), they would figure out ways to manufacture them to allow it, but since they don't, why would you? Technical: Space inside a mobile phone is at a premium. It takes more complex and cumbersome circuitry and design to allow a device to run from power vs. battery. Running from battery is much much easier and can be done smaller (and lots of other electronics/electricity reasons). Laptops are large enough and are used in a different way that makes it reasonable they can run off power directly, and then also use it to charge"
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byxg4v | How does Microsoft and Sony compete with similar specs? | Technology | explainlikeimfive | {
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"They both have a similar release date in mind since you don't want to come out too far after your competition and 3rd party developers want to know when to start making higher end games. As well they have similar price points in mind as you don't want to be way more expensive then the competition. So when you combine the two you end up with similar specs, the best most cost effective hardware that will be available for mass market consumption in year 20XX. There are only two major CPU and GPU manufacturers so both companies are drawing from the same pool unless they completely go out of left field. Sony tried that with teh PS3 and the Cell Processor and got burned."
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byxl7l | How/why do certain TV shows appear more ‘polished’, and others more ‘live’? | Technology | explainlikeimfive | {
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"The main thing is that they use different cameras. Soap operas and lower budget shows use different equipment to shoot. High production value shows are done with cinema cameras and equipment, while cheaper productions are done with TV cameras. Back in the days of filming on a film, the difference between things filmed in studio and outside on location had a clear quality difference. Nowadays it isn't as clear. These different camera rigs require different kinds of crews to work. They also shoot using different formats, and edit differently, use different color correction and such. Not every production uses the same methods. Generally more money = better gear and more time to polish the end product. But sometimes you don't need top of the line gear. Would a run of the mill soap opera really benefit from having better cameras and editing?",
"It's partially the lighting, and partially the camera style. Soap operas are evenly lit and shot with multiple cameras, shows like GoT are done per scene in single camera setups and have a lot of editing done after, as well."
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byxtdl | What exactly is a game engine, and why are some better or stronger than others? | Technology | explainlikeimfive | {
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"It's a framework, somewhere between programming language and development environment. Think of it like a foundation over which you build games. So instead of having to start a game with a blank page and having to write every piece of code for it. You have a basic makeup and as a developer only have to fill in the parts that set your game apart from others. If this is a blank program: \\[ \\] You have a hard time making a game. If this is a game engine: \\[ < Add your character here > , < add your rules for movement here > , < add your textures here > \\] The engine handles the rest of it, you just fill in the blanks. & #x200B; Can't say what makes one better than another, depends on what you want you game to look, or feel like. Some have more options, some are slower on older hardware. A good developer can make the same game on 3 different engines, it's just a matter of how long it's gonna take."
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byy76s | Why can't phone cameras take pictures the way I see things at night, even though they can adjust for brightness? | Technology | explainlikeimfive | {
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"A camera is a very dumb tool with lots of limitations. Those limitations can be mitigated with technological advancements, but at the end of the day, it's just a hunk of metal glass and plastic trying to capture photons. The way that you see with your eyes is very nearly magic. Your eyes bring in light, the light is picked up by your rods and cones, and then the info is sent to your brain where all the magic happens. Your brain can filter things, adjust for things, and even make up information where there really isn't any. Your eyes and brain also have a very very wide \"dynamic range\" which is the range of brightness levels you can perceive at once, from really bright lights and into deep dark shadows. Some of this is the nature of our eyes, and some of this is down to the enormous power of our brains processing the information quickly. More importantly, your vision is set up specifically to be giving you information needed to hunt, defend yourself, be aware of threats or resources, etc. So when there are flaws or deficiencies, your brain doesn't really alert you to them, it just does what it has to do to keep you safe and healthy. You may think that you can see very well in really really low light where a camera sees absolutely nothing, but if you really examine the image your brain is perceiving, you may notice that you are essentially seeing black and white, because we don't pick up color well in ultra low light, and yet your brain will do its best to show you \"false color\" because you know \"that truck is red\" even if you can't see it. So you brain will basically paint the color in for you based on your knowledge. A camera can't (yet) use the intelligent power to make those adjustments the same way your mind can. It just shows you everything it can technically capture, without any fakery or trickery to help fill in blanks, remove distractions, or make up for deficiencies. They also have far lower ranges of capabilities between bright and dark spots, so at night where you have a very bright street lamp and a very dim car interior, your eyes will show you both levels of exposure, but a camera will have to pick one or the other, and you'll get a blown out white light and an interior you can see, or a well exposed light and a black interior. The technology just isn't there yet to expand that dynamic range. On cameras with larger sensors, the dynamic range is better, but still very limited compared with the human eye. The camera also can't fill in the blanks when it comes to colors, so what might look vibrant and detailed to your eye is going to look muddy and \"accurate\" in a photo.",
"Camera sensors are typically not sensitive enough to pick out details from very low light scenes. Human eyes aren't well suited for low light either, considering that many more animals have better night vision performance than us, but we still have better eyes than cell phone cameras. There are cameras that are more suited for low light, but they often have very poor *normal* light performance. So making one that can do it all is pretty difficult.",
"Your phone camera has no aperture to adjust how much light comes into it like our eyes do. So that's one measure of control gone. Instead phones have to work purely on their ability to separate signal from noise. Digital cameras detect light with something called a CCD, which is composed of various cells that convert light into an electrical signal. The retina of the eye works on *vaguely* similar principles. In both cases, there's a certain amount of \"signal\" that comes from a proper reaction to light and \"noise\" generated by spontaneous fluctuations in the media. When you have a lot of light coming in, the signal is very strong, and the noise is very weak. Imagine noise as random numbers from 0-5 being added to data that ranges from 0-10000. But when it's dark, and the data coming in is only 0-50, noise gets very hard to filter out. The brain is just really, really good at filtering visual noise. Part of that is because a lot of what we see is actually the brain extrapolating from the signal it gets and not a picture perfect, \"pixel\" for \"pixel,\" true view. This is why optical illusions work on us, because they mess with the processing and interpretation we do on the data. Our brain fills in the gaps in data and gives us an illusion of clarity we don't actually possess. **TL;DR, True ELI5** Both struggle to make out shapes in the dark, but our brains are really good at picking out what's important, and they guess at stuff where they can't really tell. Phones can't do that.",
"Your eye is not a camera. It works on completely different principles. The eye adjusts for darkness with the aperture, and cameras can do that. It also handles dim conditions differently, triggering nerve impulses when a single sense cell detects light. Cameras operate on a frame concept that's intrinsically more susceptible to noise.",
"The cheap and super small sensors and circuitry in phone cameras limit their capability, while quality DSLR cameras are much, much better. However, regardless of how close cameras get to accurately capturing photons, there will still be a major difference. Our brains do not use a single 'capture' of light to form an image in our brain. What we see is more like a video, but more complex, with extensive processing occurring to generate our perception of our environment. This includes depth perception. Cameras capture light, expensive cameras can capture light with similar sensitivity and resolution to our eyes. No camera can perform the processing our brain performs to generate an internal image."
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byyntb | How does a game in development for 7 years stay up-to-date with trends, graphics, etc? | I am referencing CyberPunk by the way. | Technology | explainlikeimfive | {
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"Depends on the development cycle. If they use a static model, they don't keep up with trends, but graphics tend to be fairly mutable. If they use a dynamic agile model, you'll notice elements of the game developed last will have more polish to them. & #x200B; Graphics, so when artists make models they make them stupidly highly detailed, then use a scaled down version for the game, if the specs go up and tech gets better before (and sometimes after) release, they just re-create from the original model a slightly better one (more polygons, better textures, less scaled down). Writing, if it's done and seems good enough, they kinda leave it, but patches can be introduced later via updates. Trends, long dev cyles mean that sometimes you just have to pick something that won't go out of style, by going hyper futuristic, or old medieval, or fantasy. You'll notice games that don't age well tend to be contemporary or sims (though sims tend to make updates by releasing a new version every year with small updates, up to a point, and some just fill a niche that has barely any competition; see Flight Sim)",
"Former game developer here, & #x200B; Graphics in game make what I'll call for the sake of argument \"generational leaps\". By and large, visuals trend with the game console. It makes sense, consoles are essentially fixed hardware - for a given generation, a game released day 1 with the console will run on the last run of that machine's production, and the last game published for that console will run on the first release machines. So the popular game engines out there are tuned to deliver the best possible experience for those machines. It makes the engine developers the most money. & #x200B; Now, if your development spans generations, then it's still not hard to hit your target. That is because studios may be made aware of their target specs before the console is released - they have to get games made for release day, after all. But also, game console hardware is not the latest and greatest technology. In fact, it's about the cheapest hardware the manufacturer can get, with a contractual deal from their supplier to make that hardware for the duration of the console run. So even if you don't know what you're aiming for, you can take a conservative guess and still hit your target, perhaps with some adjustment later in production. & #x200B; PCs by comparison are a different beast. And here you're going to see a diversity of different engines and technologies. PCs are hard to make because you have a very wide variety of machines to target, with a wide range of capability. These games have to be very flexible regarding it's rendering capabilities, being able to automatically detect what the hardware can and can't do, and give the user the ability to turn the remaining features on and off, up and down, without having to reset the game. And you have to try to make the game look good under all possible combinations? Jesus fuck... The only reason you see a stupendous awesome PC game is if the studio wants to showcase an engine they want to sell. The PC market is tougher because there is a lot of comparable and competitive technologies, there are fewer studios who compete in the PC only market, which is a tiny fraction of the whole, and your awesome whiz-bang engine isn't any better than the other engines already tuned and established on the consoles. & #x200B; But any game published today that is at the bleeding edge of graphics capability is collaborating with the manufacturer to be their killer app that showcases the new technology."
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bz1879 | How do you make an operating system? | Technology | explainlikeimfive | {
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"With great difficulty. You have to start with the hardware, will it run on regular modern computer hardware or its own custom thing? You write code that will communicate with the hardware in a structured predictable way (usually assembly/machine code). You write it in a way that it can store and manipulate data. On top of that, you create a layer of abstraction, a way to communicate this information to the user... could be as basic as a couple of LEDs, by telling the hardware: \"hey give 5v to this pin\". It can be more advanced, like draw this on the screen (but that's it's own topic). Once you have that layer you have a basic OS, the first ones that use modern monitors simply had a text interface that would ignore commands it did not understand.",
"Operating system basically provides some sort of environment for programs to run in. So first off, you have to know how to code. That's just you telling the computer what to do. You have to translate this code into something your computer then understands. Usually this is machine code, especially on operating systems, but on some programs you could have interpreter running. If you write code and translate it to some code, presumably machine code, this is called compiling. After this, if you load this program to your CPU memory, it starts running. So next up, you gotta start figuring out how the operating system does what it needs to. At its simplest, it only needs to make sure the system boots up, and launches programs it needs to, and ensures those programs have *enough* guidance so they can run freely enough. Nowdays desktop operating systems assume that computer might have multiple users, and they can be running multiple programs and some of those programs may be faulty or even malicious. But if you want to make a really simple system, you could just make the programs to be run yourself, and implicitly assume that those programs will behave nicely, and even co-operate. Co-operation could be used to make sure every program gets to run on CPU. CPU(we assume single-core processor because it simplifies, multi-core causes untold horrors) can only run one process at a time. So if you have two processes, A and B, and then OS running separately, if you have A running, it has to relinquish the control of CPU somehow. No other process can directly ask to be run, and in our simple system, OS isn't taking care of this either. So A, B and OS must all co-operate and relinquish voluntarily control of CPU and load the next program in at appropriate times. With multiple programs, this gets complicated because you have A, B, C, D, ... all have total control of CPU, and if any of them fails, the system fails. Modern OS's use so called scheduler to do this task. It's a special, very light-weight program that gets loaded at regular intervals to check if program should swap. Programs still can voluntarily relinquish control as well. To make this happen, initially it was a co-operation problem still, but nowdays hardware has special \"administrative mode\" which is supposed to be only used by operating system. Code run in this mode can set built-in timers that, when activated, forcibly kick out the current program and load the scheduler instead. This is specifically built into the hardware. Memory management is important as well. If you want to go for simple OS, you could have every program just co-operate with memory. It's a giant table of values and you could have each program just coordinate, \"I take this chunk here, you have that, and you have that\". But again, more programs you have, the more difficult this coordination problem becomes. So instead you divide memory into segments. Each program is fooled into thinking that chunk of memory they get from OS is actually the whole memory the computer has. They cannot see anything other programs do. Again, operating system runs in administrative mode and skips this restriction. And if malicious program gets to run in this mode, well, they can read and change memory of all other programs on your disk. There also is built-in hardware that is translating the requests so when program A says \"I want memory address 0x11\" or something, that 0x11 is actually virtual address. There's a piece of hardware that has, set up by OS, a table that tells it what memory address physically 0x11 corresponds to. These might be scattered all around the RAM modules you have, and the program will never even notice. So you can just write your code \"Write something to 0x11\" and when it's running, you're actually writing to some random spot on memory but from your programs point of view, it's as if memory address 0x11 was real. After you have this, you can now start writing so called shell for your OS. Shell is basically the programs bundled in with the core that allows you to do stuff. Simplest solution again would be text-only shell that just asks you to log in and open programs via text prompt. But if you want to be more fancy, you can make graphical interface which does things like, gives windows to programs and allows drawing graphics and that sorta nonsense. On Linux, there's actually a wide variety of interchangeable graphical shells available for you to choose. The kernel of the system(scheduler and all such important parts) stays the same, but how it looks changes. That's kinda it. I tried to keep it short while providing at least some key details so it doesn't feel completely hollow as an explanation. I also may have made mistakes here, I'm not really comfortable with hardware part of computers so my attempts to explain how hardware does certain things has pretty high chance of being wrong in some ways. Hopefully the gist of it remains correct",
"Very rarely does anyone build their own OS. If someone needs their own OS, they use the Linux kernel. Linux is free, stable and open source. Building your own OS would involve. 1. Actually writing the OS kernel and shell. This is a massive undertaking depending on what you want it to do and what hardware it will run on. 2. Writing your own hardware drivers. If you want your network card, GPU and USB ports to work, you will need device drivers, which tell the kernel how to use the hardware installed on the PC. 3. Write your own programs, as nothing will run on it. 4. Provide bug fixes and security patches. & #x200B; This is why everyone just uses Linux. It already does all of this at no cost, and there are tons of programmers who are already familiar with Linux.",
"An operating system is just a set of (usually a lot of) computer programs. So, you basically need to write all the necessary programs. Computer programs are written using programming languages. Most of the operating systems are (mostly) wrote in C Programming Language, but it's not a strong rule. Some small parts of the OSes need to be written in \"assembly\" - a low-level programming language used to directly control the computer's processor - but for the rest you have quite a wide set of options. Starting from the beginning: what happens when you start your computer? It first starts it's internal software (e.g. BIOS or UEFI), and after some internal checks it gives control to a component called \"boot loader\". Boot loader is the first non-builtin program started when your computer is running, and may be considered a first part of the operating system. Writing a simple boot loader that just displays something on the screen (and maybe reacts on the keyboard) is relatively simple, and such a thing may be already called a (very) simple operating system. However, in 2019 you expect a bit more from an OS, thus what boot loaders usually do, is some initial configuration of the hardware, loading something called kernel (see below), ensuring that it has everything it needs to run on its own, and giving it control over the computer. (\"Loading\" here means, reading it from a disk to the main memory (RAM)). The kernel is basically the most important part of an operating system. This special program directly controls the two essential components of your computer: the central processor (CPU) and the main memory (RAM). Every computer program requires these two, they simply cannot \"live\" without them (literally, just as you can't without oxygen or food), but you can't just let them in and allow to do anything they want. This is why in all the modern OSes it's responsibility of the kernel to coordinate the way all the programs use these two most important parts. Coordination of CPU usage is called \"scheduling\", of RAM is called \"memory management\". Kernel is also responsible of providing a way for the other programs to communicate with each other. Having these basics - programs having access to CPU and RAM, and means to talk to each other - is a cornerstone on which everything else in the OS is based. Next very important type of programs you need are device drivers. Driver is a special program, whose only purpose is communication with a single type of device, either inside of your computer, or connected to it. They know the details about how the device works and allow other programs to use the device without knowing all these details. E.g. a printer driver knows all the details on how to make the particular printer model to print, so other programs can use the driver and don't have to talk with the printer directly. The basic device drivers you need are the ones for disks, keyboard, maybe mouse, and the display. Less essential ones include network interfaces, printers, scanners, and all the stuff you plug into your computer. There are also other types of drivers you usually need, not strictly related to the devices, but to some functionalities of the system. One example are filesystem drivers. File system is a way in which your files (and directories) are being stored on your hard drive. The details on reading or writing to a drive is a thing of it's device driver, but organizing these data in a meaningful way is the thing of the file system. How it works is a very long story, and this is exactly why you need a single driver for that - so that other programs can access files without knowing all these details. Another type of drivers are network stack drivers. Again, they are not meant to control the network devices directly (this is responsibility of their device drivers), but to organize bytes sent over the network in a meaningful way. This is yet another very long story, and again, having these as part of the system makes it possible for the other programs to use network without caring about all the internal details. These were the major \"internal\" programs - programs, the user don't ever see, but which are essential for an OS to work. So, having that, you still have to prepare all the things visible for a computer user. The environment the user sees is usually called a \"shell\", since it effectively shells them from all these internal details they don't have to know. Basic function of a shell is giving user some possibility to start other programs. A command line is a simplest kind of shell, where the user runs programs by typing their names on their keyboard and pressing ENTER. Command line was the first kind of shell ever and sometimes it's still enough, e.g. in a server computer. However, most of the home and business users expect a graphical shell, where they run programs e.g. by clicking on their icons. Programs should also have a way to display their graphical content, and having more than one program visible at the same time is a common thing. All these things require a few special programs: a display server and a window manager. They coordinate the way various programs display their content on the screen, e.g. in rectangular boxes called \"windows\". Most of the modern operating systems are multi-user, which means, a single installation can be used by multiple persons (sometimes at the same time), all having their own storage space and settings, access to which is usually protected by passwords. These functionality is mostly implemented by special programs called user manager and/or session manager, but to make the isolation between the users possible (e.g. to avoid one user reading files of the others) they require appropriate support on all the levels: kernel, drivers, filesystem, display server, etc. Of course, all the aforementioned components need to be customizable. User has to be able to configure the system for their needs, e.g. to set their own password, setup a device, change system language, background image, etc. These programs are also considered a necessity for a modern OS. Having all these gives you a functional system. Functional, but useless. Now you need some actually useful programs for the users to run, like internet browsers, text editors, games... These programs are often called \"applications\", to distinguish them from all the other \"internal programs\" mentioned above. But that's another story, preparing applications is usually considered a separate thing to development of an OS, although most of the systems come with some set of basic applications on board. & #x200B; Edit: I assumed here a modern operating system aimed at desktop/mobile home/business users. Based on your particular needs, you can obviously skip some elements. The perception of what belongs to the OS also changed over the years, the most of what I described wasn't consider \"necessary\" until well into 1990s, e.g. MS-DOS was basically a filesystem driver with a shell. & #x200B; Btw, Wikipedia page: [ URL_0 ]( URL_1 ) has a lot more details regarding almost everything I mentioned."
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bz23yq | /dev/null, /dev/random, /dev/urandom and /dev/zero | I've been reading about this files and also I have tried to inspect by myself about this files (file, ll, Stat and some other commands) but I just don't understand them. Can someone please explain me what are these files and how can I used them? | Technology | explainlikeimfive | {
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"Whenever you read from or write to a file, you don't directly access the file. Instead, the operating system does that for you. These three files are special in the sense that when you use them, the OS pretends they are real files when in fact they are \"pretend\" files. When you try to write to /dev/null, the OS simply discards your input. When you read from /dev/zero, the OS just gives you a bunch of zeroes. And when you read from /dev/random, the OS just gives you a bunch of random numbers.",
"Everything in /dev/ is not a real file on a disk, but a sort of pretend file — you can read from them and/or write to them, but their contents or effects live only in software, and are not written down on a disk.",
"/dev/null is end of file when read and discards data when written. It's convenient to redirect input for programs that otherwise expect a keyboard, and discard unwanted output like directory errors from \"grep < something * 2 > /dev/null\". /dev/random and /dev/urandom are the same driver, which collects entropy (randomness) from activity on the system. /dev/random will delay until it has collected enough random bits for the request, /dev/urandom will \"make up\" random numbers (using a random number generator) if necessary, so it won't block. /random provides stronger numbers for things like cryptography, the /urandom is good enough for games and similar programs. /dev/zero discards written data, and returns just zeros. I've used it to rapidly (and only mildly securely) overwrite files, and a source of data to create files of fixed size.",
"These are not regular files, like a file you save on disk. They're virtual, which means there's a piece of code in the operating system that makes them behave in a special way. Basically, doing e.g. \"echo Hello > file\" causes your shell to open file named \"file\" and writing the bytes \"Hello\" into it. What happens if you replace \"file\" with \"/dev/null\"? Well, shell will do the same thing, but the kernel knows that /dev/null is a special device and the bytes the shell tells it to write will be simply discarded. This is also the idea of that special file: to make everything you write to it just disappear. Why is it useful? Well, there're many programs that expect being able to write some data *into a file*. If you give them /dev/null instead, they'll behave like usual, telling kernel to \"write some bytes there\" - which kernel will accept and then just drop. Usual use case for /dev/null is redirecting output from a command to prevent it from cluttering your terminal with some useless messages. Opposite to that are files like /dev/zero, /dev/random and /dev/urandom. They're also special files, but their speciality makes them behave different when being *read from* (not *written to* like in case of /dev/null). /dev/zero, when being read from, just produces infinite sequence of \"zero\"-bytes, so bytes with 0 as their value. \"infinite\" here means \"as long as you continue reading, you'll always get zeros\". How is it useful? Again, some programs want some input, and feeding them with zeros is sometimes useful to make them run and not complain. /dev/random and /dev/urandom are similar to /dev/zero, but instead of 0-bytes, they deliver random bytes. This is more useful - if you have a program, that somehow reacts on the input data, you can make it to behave randomly by feeding it with random bytes. Many programs use random bytes, e.g. in games they're used to make the play unpredictable. Even more important is their usage in security-related domains, although it's a big topic on its own. Why two of them? Well, there's something called \"pseudorandomness quality\" - since computer can't directly generate random numbers (it's a perfectly predictable machine), it tries to gather random noise from various sources (like devices it has on board) to make the generated bytes \"more random\". How it's related to the files? Well, using /dev/urandom you'll get infinite stream of bytes, but there's no guarantee of them being of a good \"pseudorandomness quality\". For some uses it's not that important, e.g. games, but security-related stuff usually require highly random values. This is why /dev/random is useful - it'll only deliver random bytes if system determines they're of a good quality, but not necessarily as fast as you can read - so you may have to wait a bit for your random bytes. So, all this files are only \"virtual\" - they aren't store anywhere persistently, they just use \"file metaphor\" to implement some useful, special behaviors."
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bz2toy | why do some file transfers have such variable transfer speeds? | like for example if there is a lot of smaller files, it seems to really make the transfer speed slow down. but some transfers in general seem to have completely random transfer speeds, why aren't they able to use the full bandwidth of the connection? | Technology | explainlikeimfive | {
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"Fragmentation and connection protocol message size limits. When files are stored in a drive the drive allocates contiguous blocks of data to most files if they need it. But if you have lots of small files the drive needs to search for them all over its memory to then copy them to the bus and send them to their destination. Search, find, copy, send. Search find copy send. Over and over for many files vs 1 long stream of continuous data. & #x200B; In addition when being sent over network or even local protocols, they have a max message size, so the device will cut up the file being transferred into: 1. Header (what is the file, how big and where is it going) 2. First chunk of data 3. Second chunk of data 4. Thir... you get it 5. ... ?. End of File While sending these messages, sometimes the computer needs to check to see if the connection is still alive... so stop transfer (rather pause), check, wait for reply, continue with a new header that also says 'I'm part of the previous message'. & #x200B; This happens very quickly in many many small messages, so you can see how the connection might flutter up and down in speed if it has to stop and go."
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bz4jtf | How do movies go from the raw footage (film or digital) to 4K? | I’m mostly curious about the process of converting it from its raw form into ultra high quality, especially if the movie is older. But the question also probably applies to DVD and Blu-ray as well. | Technology | explainlikeimfive | {
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"With digital recordings, the raw footage is usually higher quality than 4K (IIRC, 8K is fairly common). For final release, you just render the video in the release quality and write it to the DVD or blu-ray (or digital download/streaming service). With film, we're lucky because film is actually very high quality. People tend to think film has low quality because back in film days, the film *duplication and distribution* technologies were not-so-great, making the version in theaters of lower quality. To go from a film recording to a 4K digital video, you essentially put each frame of the film into a digital scanner (like the one in a multifunction printer) and make sure they line up with software. You can optionally use software to remove defects in the film from the digital file. You then send the scanned images off to be written to the DVD, bluray, etc.",
"While it's correct that 4K video is often shot in higher resolution and converted for the final product I think your confusion may come from what makes a RAW image RAW. RAW means that the image has not yet been processed into a compressed file yet. Essentially the RAW image is all of the data captured by the sensor, and hasn't thrown some out in creating a JPEG. This is why RAW is really only useful for professional or enthusiast use. There is maximum color and light information that can be tweaked. It's not great for your phone or low end digital camera as in those uses having an easily shareable format and less memory use is more advantageous."
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bz8wgv | Why electronics suddenly stop working | I know about planned obsolescence, but HOW does it happen? How can a TV mounted on a wall for 3 years up and die all of a sudden? How will a network router suddenly give up the ghost after years of working? | Technology | explainlikeimfive | {
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"The most common failure points is the solder that connects the different internal pieces of the electronics to each other. After too many heat cycles they can break down and can desolder themselves which effectively breaks an electrical connection. Depending on what solder point breaks it can range from behaving weirdly to outright not turning on. Another failure point is the integrated chip itself. Inside the chip are tiny transistors and those transistors can go bad."
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bz99jj | Why do the ads before YouTube videos never seem to have trouble loading but the video itself will barely play at 360p? | Technology | explainlikeimfive | {
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"Because they are on different servers. The video might be an obscure one that only a few hundred people will ever watch but the advert will be pushed to millions of people watching a multitude of videos so it’ll be on a better server.",
"Often the ads are robustly buffered on a closer server because they'll be shown to a lot of people, but the video itself can be anywhere, and may not be given enough resources somewhere along the chain.",
"And why are the ads so much louder? And why do the ads have annoying music that rapes your ears? And why do the ads have a thumbs up/down option, as if anyone would thumbs up an advertisement?",
"You know how in the pantry, we keep all the cereal and stuff on the lower shelves? And then how we keep the pots and pans we don’t use very much up on the top shelves because it requires a ladder? Well, the ads get used a lot, so we put them in easy reach. And the video you want to watch doesn’t get used as much so it’s kept further away and takes a little more work to get up and running. (ie the ads are on better servers because they are used constantly while the videos with lower view counts are called up less often.)",
"The ads are pre loaded on the CDN server like Akamai while the video (in some cases) are buried in some old google server that's not often used. Content delivery networks are the backbone of the internet. URL_0",
"The ad is the product Youtube actually sells. The video itself is just the bait to get you to show up for the ad. Youtube obviously cares much more about one of these than the other, and allocates their server resources and bandwidth to satisfy their customers (advertisers) rather than viewers.",
"This is hard to ELI5, but the basics are: * The consumer pays for an internet connection. * YouTube, Netflix, and other services also pay for their internet connection. * Advertisers *also* pay for their internet connection. * Everyone pays for a certain amount of bandwidth. You may have a 100mb plan, advertisers may have a huge amount, where YouTube has an unfathomable amount of bandwidth. * Due to so much traffic, YouTube has a new \"peering\" arrangement (like a fancy monthly plan), which used to be free. Due to the massive amount of traffic being used, ISPs and backbone providers basically forced YouTube to pay for their traffic *in addition to consumers paying* so they could handle it. Basically, the ISP's argued it was unfair for them to handle the burden of all the video traffic without compensation because it was inundating their services and causing problems for everyone - providers and consumers. * The traffic that comes from YouTube goes through dozens of service providers, each with varying speeds and quality, to get to you. Better equipment means better performance. * The advertisers are *not* on the same connection as YouTube, and don't have the same amount of traffic. Instead of handing uploads, streaming, playing, and whatnot, advertisers *only* stream content. Their advertisements are often 5 to 60 seconds as well, so not nearly as much traffic as YouTube. They can send you a video quickly because they are smaller and more efficient. If you want the technical details, read this - I think it's well written and pretty interesting: URL_0",
"Can we just make the moral of the story to use adblock?",
"So you click on a YouTube vid, and an ad plays fast and just fine. Then the vid you wanted comes on and its all slow and clunky. Suppose you go to a restaurant, and the restaurant knows it will automatically have to give you something(the ad/breadsticks in the following example). Lets say you're at olive garden and you order chicken parmesan.. the ads would be the free breadsticks. The breadsticks are already cooked back there, knowing that you'll get them anyway. They are prepped and ready to send out at any time. The chicken parm is the video, they dont have the chicken parm ready for you because you have to order it before they cook it. When you click a vid, the breadsticks/ads are fully loaded on their end and ready to go. The video has to be loaded as well, and its not been premade for your immediate consumption.",
"Ads are sent to your device from servers that are closest to you and are also much better than the video’s server. Money takes priority.",
"Because you are not YouTube’s customer, you are their product. Advertisers are their customer and so they prioritise the needs of the advertiser over your own. The advertiser needs to show you ads and does not care about showing you videos.",
"Haven’t seen any real explanations yet. It’s not because of any evil scheme. The way internet works, put simple, is you ask your server for something and they find it and bring it to you. If it’s something they haven’t seen before, or don’t see very often, they have to find it first. There aren’t that many different ads. If you use YouTube a lot you might even see the same ads several times. Because of this, the server will save the ad in its cache. This way, when the ad loads it’s just the server sending it to you, but when the video loads it has to talk to a separate server which hosts the video.",
"There’s a lot of fundamentally incorrect information in this thread but I am sure this comment is going to get lost. The most likely reason why ads play fine has very little to do with ad location. When you initially make a connection to a site or anything on the web, most Internet Service Providers give you a burst of speed with your connection. If you have ever used like SpeedTest, you may have seen that initially your internet speed spikes and then comes back down to your published speeds (especially true when you don’t have Fiber or a bit slower speeds). This initial burst of speed is to help speed up your experience on the web, but if you request consistent throughput they will then hit you with your speed cap. So what is likely happening is you are connecting, getting a burst of speed which is enough to quickly download the 6 or 14 second ad and then your speed is backing off and taking longer for your regular video to load which is causing the kick down in resolution initially until it can load far enough ahead that YouTube feels like your experience won’t be interrupted. At which point it will start downloading the video at higher resolution and bump you back up. There’s one other possible reason which is you have a mobile plan that limits you to 480 (pretty common with major US carriers) and ads are shot with higher quality lighting and equipment, and the lower resolution that you are forced to by your mobile provider might be more noticeable on lower production YouTube videos.",
"To add to the other comments about hosting... The ad is much shorter, so will have a reduced file size. And it's likely been optimized a lot better than many YouTube vids.",
"I haven’t seen it mentioned but most commercial companies have the budget for top of the line proprietary compression algorithms. This allows them to have the best possible video quality and playback in even the worst of conditions. Their ads are optimized so that the file size is exponentially smaller than most videos would be. People pay good money for these types of things because you’re guaranteed a return on your initial investment.",
"An answer that I don’t see in here is that the videos themselves use something called DASH playback. Basically, it used to be possible to buffer youtube videos to 100% by pausing and waiting. Now videos will not buffer more than a few seconds ahead. A few years ago you could disable this which drastically improved playback quality. The ability to disable this feature has since been removed, however, making youtube video playback essentially garbage on slower internet connections."
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bze4tt | Why it is so difficult to create ps3 emulator? | Technology | explainlikeimfive | {
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"The PS3 uses a radically different architecture than found in the average home PC. The PS3 used multi-core Cell processors instead of X86-64 as the PS4 does, so these processors need to be fully emulated. The problem there is that there's not enough of a performance gap between the Cell and a reasonably speedy X86-64 processor, so you don't have a lot of headroom to perform realtime CPU emulation."
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bzfrx5 | What is TCP/IP and why is it so prevalent in modern day computing? | Technology | explainlikeimfive | {
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"Communicating on the internet generally uses 5 layers. Making it layered makes it easy to tackle the different subproblems individually. Let's take an email as example. I want to send an email to you, these are the questions at each layer: * **Application layer**: What exactly is an email, compared to a webpage, a random file, ...? What exactly is an email address and how do I define you as the recipient, CC, BCC? How do I encrypt it? * **Transport layer**: How fast can I send my email? How fast can you receive it? How can I be sure you received the full email in order? Does it even matter whether it's in order or not? (What TCP does) * **Network layer**: How do I get from my computer to yours? Which routing path is the shortest/fastest? What if this router along the way fails, is there another route? (What IP does) * **Data Link Layer**: How do I get from one computer to the next? (along the route we found above!) How do I send something across an Ethernet wire? What about wifi? (Ethernet, Wifi, Bluetooth are all defined here) * **Physical Layer**: How do I transmit bytes over my connection, both wired as wireless? So TCP is in the Transport layer, and provides all the reliability guarantees I questioned: retransmits, ordering, transmission speed, ... If you don't need all of this, for example when gaming, you use UDP. Most of the internet uses TCP. If you want realiability, look no further. IP is in the Network layer, and makes up the routing. It's just the best scheme. Apart from the IPv4 to IPv6 upgrade, there is really no reason to change anything here. **Conclusion: IP and TCP are just simply the best protocols in their league. Together they basically guarantee that the message reliably gets from A to B through the most efficient route.**",
"Multiple \"layers\" of \"how to do things\" encoded into the actual network card devices and into the software that runs them. From \"how to pulse 5 volts across a bunch of wires in order to send information\" (sort of like a Morse code standard, but not really), to \"how to put the 1's and 0's in the correct order and how to check for errors\", to \"how to break up 50 gigabytes of data into chunks small enough to be sent\", to \"where am I sending this stuff, what's the damn address\", to \"I'm receiving 2939504 data packs, but they're out of order!!!, how do I piece the puzzle together so I can see the video\" to \"you want to send with encryption or without? to multiple devices or just one?\" etc. It's prevalent because computers need to send data to other computers, it's what the Internet is all about, and TCP/IP is the set of standards that tells everyone how the communication is supposed to happen. It's also prevalent because it's more customizable / easy to adapt to various configurations that companies have (multiple divisions across the globe, etc) than other standards we had in the past, like TokenRing, IPX/SPX, etc. Basically, just like with the \"format wars\" (betamax vs. vhs, ntsc vs. pal, blu ray vs. hd dvd) multiple companies had multiple standards, but eventually one won over and was adopted by everyone and became prevalent."
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bzfxbu | Car cigarette lighters/chargers | Technology | explainlikeimfive | {
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"The piece that you pull out (the piece that lights the cig) is the coil that gets hot. The hole in the dash is just the power and ground source for the cig lighter or charger. So you put a charger in the hole, it gets power and ground and charges the phone, cause it’s a charger You stick the cig lighter in( it’s a heating coil) it gets its power and ground and the coil gets hot and bright red, hot enough to light a cig. Now a coil is essentially a highish resistance load that when given power and ground will get hot.",
"The hole where the plug goes just has electricity running through it similar to a wall plug at home (though it is DC power instead of AC). It does not produce heat - just electricity. The actual cigarette lighter takes the electricity into a coil which just converts it to heat energy."
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bzin6b | What's the difference from installing and downloading? | Technology | explainlikeimfive | {
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"Instead of software, think dinner. Downloading is getting the ingredients from the store to your kitchen. Installing is turning those ingredients into a meal you can eat.",
"You buy a desk. The desk comes in several pieces, in a box. Getting the box to your house is downloading it. Opening the box and putting the desk together is installing it.",
"You order delivery food. The guy delivers the food. That’s downloading. You “unpack” the food to eat. That’s installing. You eat the food. That’s using the program."
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bzju79 | How can you pinpoint your location with GPS on your phone without service on the ground, but can’t do the same on an airplane? | Technology | explainlikeimfive | {
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"It works in plane too....if you have an unobstructed view of the sky with at least 4 satellites. Given cramped space and metal ceilinge of typical airliner body this is 50/50 chance of working if you're in window seat. But if you do it on a private small plane with a big plastic window, it works just fine.",
"GPS works by satellites sending a message with a time and location of when the message was sent, your phone can then work out how far away the satellite was when it sent the message by knowing how long it took for the message to get to it. if your phone has a message from 4 or more satellites it can know where it is in 3d space. There is no need for cell service and you can get dedicated GPS devices that have no connectivity abilities.One of the things that the US military (the developers of what most people use for GPS) have put limitations on most domestic GPS chips so that they no longer function when traveling faster than 1,000 knots (1,900 km/h; 1,200 mph) and/or at an altitude higher than 18,000 m (59,000 ft) which would explain why you can't get a GPS lock on an airplane Edit: aircraft do not normally reach these speeds and altitude therefore somewhere I have gotten my info wrong, I was told this was why domestic gps might not work on aircraft by a more authoritative source than a random Redditor (although I can't remember who) and just grabbed the numbers off a [wikipedia page]( URL_0 ) believing they were talking about the same thing.",
"In a purely satellite based GPS, it can take minutes to acquire a signal and position. And this doesnt work well if you're moving fast. When you're on the ground, there are many assisted methods of acquiring a GPS signal."
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bzjuwb | How would you go about making a search engine like google from scratch | Technology | explainlikeimfive | {
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"There are several components in the Google search engine: 1. The \"spider\", which browses through websites and collects the data. 2. The indexer, which parses the collected data and makes indexes of keywords and ratings. 3. The user front-end, where the user enters the query which gets parsed and searched against the indexes.",
"You're question is basically about Search Engines. You can research it yourself and learn how to make a simple search engine with Apache Solr (Completely open source). & #x200B; I'm a Tech Lead for my company's search engine, meaning I'm the owner of the search application. & #x200B; I'll break this up into different sections and update at will & #x200B; **What is a Search Engine? The root of a search engine is the index.** & #x200B; Well really it's an inverted index. Basically imagine a large file with different sections, each one containing a word (token). Then imagine following each word is a bunch of information separated into numbers. Each number describes a document and will be followed with a frequency (amount of times that word occured in the document). & #x200B; A document is a dataset describing one set of information. That information is separated into fields. Each field can have different data transformation steps for both indexing and querying. So for example if you're building Google, a document would probably be the page of a website. Then it might have a field for the language, another field describing a general type (ex. shopping, scientific, medical, etc.), a title field, and then a field containing all the words on the page. & #x200B; Each of these documents listed will contain that token. Then when you search something, your search will be broken up into tokens (e.g. \"hello world 123\" - > \"hello\", \"world\", \"123\"). The documents containing those words will be scored based on how many of the words they match and the frequency of said words. The matching documents are then returned to the user, ordered by score. & #x200B; **Indexing data** & #x200B; Data needs to come to the search engine., but how? That really depends on the application of the search engine. For google, that'll consist of something called a 'spider'. A spider essentially discovers web pages and then saves the data (fully parsed). For Amazon, that would consist of a Database connector which connects to where all product data is stored and then combines that data into a useful format for the Search Engine. & #x200B; This data is then separated into fields (the method in how its done can be greatly customized) and then transformed based on the field type. Once transformed, the remaining tokens will be committed to the index in the format previously mentioned. & #x200B; **Data transformation** & #x200B; Data needs to be transformed. How will differ greatly from field to field. If you have a field describing the language, you might send the data to an AI program that will auto-detect the language and respond back with something like \"en\\_US\" (English) or \"ja\\_JP\" (Japanese). Solr can actually auto-detect language out-of-the-box and it's not even AI. If the field is a description, it might contain all the < h# > tags on a page (h1, h2, h3, h4, h5) or the text with bigger font weight). Of course that would be with all the HTML stripped out. & #x200B; This is all up to you. Solr has many different tokenizers (which breaks data into tokens) and parsers (which transform tokens further). & #x200B; **Querying data** & #x200B; The search you send to Google is called a \"query\". A query is also transformed and broken into tokens etc. The are sent to the index in an OR format (e.g. 'hello world 123' = > 'hello' OR 'world' OR '123'. The tokens in your query will be looked up in the index and each document will be scored. Documents can be filtered out of the result set and even multiple documents can be combined into one via 'grouping'. Documents can also be boosted based on custom parameters. For example, if you searched 'baby blue dog' and a page contained those words many times while describing 'A Complex Process Through Difficult Grief' (why? no idea). Obviously, this may not be the best match. If you came across a page titled 'The Baby Blue Dog's Walk to the Post Office' that is obviously more related. Here is a good example of why most documents will have a 'title' field and why most query pipelines boost on the title field. Documents that contain the phrase in their title have more relevance. & #x200B; Google actually has a complex query pipeline (no surprise). They alter your query many different ways and send each form to another pipeline. It will then combine the results of all based on scoring to boost the relevance. This is a very complicated topic so I won't go into that further. & #x200B; **Advanced topics** & #x200B; Search Engines are all about Relevance and Recall. Relevance being how close what you're looking for is to the top. Recall being the ability the return all documents that match the query. The act of making a good search engine all comes down to useful data and optimized to a specific balance of relevance and recall that suits your application. & #x200B; There is also a topic called 'Head-Tail Analysis'. This is most easily explained by 'blue iPhone'. If you search for that in amazon, you will obviously get many iPhone results. However, many of these may not contain the word blue. So you would perform complex analysis on the query and end up boosting 'blue' and changing to query to 'blue'\\^5 OR 'iPhone'. This ensures results contain both and that blue iPhone's are ranked at the top by boosting the token 'blue' by a factor of 5. I'm not experienced in this topic so some of that may be off, but the main concept is right. & #x200B; & #x200B; Idk. There's a lot that can be done with Search Engines. May update some more later, but honestly getting bored of this topic."
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bzk5tg | When an OLED screen is cracked/dropped on a certain area, why do all the pixels in a column around or near the main cracking point change to one color? | Technology | explainlikeimfive | {
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"OLED stands for Organic Light Emitting Diode. The \"organic\" part of that means carbon-containing molecules that are used to make the light instead of silicon chips. The particular molecules used in OLEDs tend to be air-sensitive, so when the screen cracks, they chemically react with the air and degrade until they don't work anymore."
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bzkbc2 | Why do programs or websites think I'm using a new device when I'm not? | Whenever you use a new device, Google or whatever website/program you're using will wig out and email you to confirm it's you. But quite often I have this happen while using my only laptop using software/websites I've used dozens of times before. Why is this and how does device identification work? Does it check for new IPs or MAC-addresses or what? And why would it be tricked so often into thinking an old device is new? | Technology | explainlikeimfive | {
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"Whenever you visit a site and authenticate, it saves a file called a cookie on your computer. When you revisit the site, the browser sends that cookie along. Then the site knows you're you. If you clear cookies, the site no longer knows it's you and needs to authenticate again."
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bzkrt7 | Why do software updates skip numbers. E.g. 1.17 to 1.34? | Technology | explainlikeimfive | {
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"text": [
"There will be internal versions of builds that may not be ready to release into the wild due to bugs or incomplete features. You need to keep track all versions for tracking and QC",
"There are some standards out there but only loosely followed as anyone can make up their own scheme. For example in the open source world public releases are usually even, and pre-releases are odd. Going from 0.12 to 0.13 will be backwards compatible, but going from 1.8 to 2.0 will have breaking changes. These are \"major\" releases vs \"minor\" releases. If you're interested in the details see URL_0"
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bzl5xr | How does wireless phone charger work? | Technology | explainlikeimfive | {
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"There are two coils. One in the phone, one in the charger. The electricity from the outlet flows through the coil in the charging plate. This creates a magnetic field around the coil. When the coil in the phone is on the plate, the magnetic field induces a current in the phones coil, which charges the battery. Src: my physics 2 class",
"Its two coils that make a current through surfaces. One on the phone and one on the charging pad. Sorta like a magnetic field, but for charging.",
"These devices work because they are able to use magnetic energy to bound a device to it’s charger and charge it, which is better than having a port, which substances like water can come into contact with and potentially damage the device, so a lot of devices that are water resistant also rely on a wireless phone charger to charge the device.",
"Inductive charging (also known as wireless charging or cordless charging) is a type of wireless charging that uses an electromagnetic field to transfer energy between two objects using electromagnetic induction, the production of electricity across a magnetic field. Source: URL_0",
"A wireless charger + a smart phone is much like a transformer. A transformer is two coils of wire, one wrapped around another. Depending on how many windings each coil in the transformer has, the voltage of the incoming Alternating Current might be stepped up while the amperage is stepped down, or vice versa. Some transformers have the same number of windings in both coils, as I believe is the case with wireless charging. Transformers only work with alternating currents, or Direct Currents that vary (but don’t cross back and forth between positive and negative, as AC does). This is because a steady Direct Current produces a steady magnetic field, and a steady magnetic field in the first coil of wire cannot induce a current in the second coil, but a current that is always changing *can.* With Qi (pronounced “chee”) wireless charging, a thin, flat coil of wire is in the back of your smart phone. When you place the smart phone on the charging stand, this places the phone’s coil of wire next to a similarly thin, flat coil of wire in the charging stand. The coil in the charging stand is just like the primary coil in a transformer; the coil in the phone is just like the secondary coil in a transformer. It’s not *as* good has having one coil wrapped around the other, but it’s good enough. The Alternating Current flowing through the charging stand’s coil induces an Alternating Current in the phone’s coil. Additional circuitry in the phone converts the AC to DC, which is used to charge the battery."
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bzld7h | Why are wall outlets 110V or 220V? Those seem like such arbitrary values; why not 100V? | Technology | explainlikeimfive | {
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"In many parts of the world, electric companies sprung up, each making their own flavor of power (certain voltage, amperage, cycles per second, etc.). This caused one really big problem: you buy a lamp and it works in your house, then you move to another part of town, and it won't work because the power is different. & #x200B; At some point, it was necessary to standardize the way power works so that there was interchangeability, technicians didn't require retraining, etc. In the end, 110/220 were completely arbitrary. It could have been 150 or 200 for all that matters, as long as everyone used the same one in the same country.",
"This might not be a simple ELI5, but the history is based off of common 1.5V battery cells and 6V DC power supplies before AC was widely implemented. Any combination of power could then be made with multiples of 6V (6V, 12V, 48V, etc) and they were sometimes rounded for simplicity. Thus 6V x 40 DC batteries = 240V. But through the AC and DC \"War of Currents\" between Edison and Tesla, Tesla won with an implementation of AC and originally planned 240V but decided 120V (half of 240) was safer in the household and more efficient at 60Hz. 240V was originally chosen technically because of phases and less line loss during transmission, but probably more detail than needed for ELI5. 120V was also thought to be enough to power most household appliances and probably more importantly the original filament light bulb was designed to be used between 100V and 130V. This alone might be the easiest ELI5 reason - everyone in that day and age wanted lights like today's cellphone. Additionally, all US homes are still fed with 240V at the main panel (2 hot legs) but most outlets except for dryers, ovens, etc only get one hot leg and therefore 120V power. The US then standardized on 120V and AC beat out DC. Most of the rest of the world just chose 240V, which is arguably more efficient and accomplishes the same thing. In cases like when England rebuilt after WW2 it was that 240V was more efficient for transmission and therefore required less copper wiring so economics played a big part of that decision. You can find out more technical detail, but this is probably enough for ELI5.",
"It was tough in the early days of electricity to figure out what was the best voltage. Edison liked DC, it worked well but required heavy wires and could only be sent short distances from the generating station. Westinghouse and Tesla liked AC which didn't require heavy wiring, but was more dangerous to work with and required heavy transformers, but it could be sent long distances with ease. So many different schemes were tried, and they settled on 110v as a good balance between wire thickness and distance and dangerousness. Plus it probably just fit well with the generators they had built. That's why a lot of things end up like that. Some guy built something and arbitrarily picked a figure because it made it easier to build and therefore cheaper than all the competitors.",
"you may be surprised to find out that the power coming out of your outlets isn't actually 110/220/whatever the standard is in your area. don't recommend this to people without some background in working with electricity, but you can check an outlet with a multimeter designed for the job - has to be one designed to handle wall socket currents, cheap shit will explode in your hands, don't do it. I can see anything from 100V to 116V in Toronto in the same house on the same day. Tokyo had clean power, never budged from 100v."
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bzoyd9 | How do airplanes vanish from Radar? | In the last few years there have been multiple planes that have just dropped of the radar and vanished. Some more famous like the Malaysian airlines plane and some local incidents. Aren't we already at a technologically advanced enough level where it should be virtually impossible for planes with no cloaking tech to vanish off of radar? | Technology | explainlikeimfive | {
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"Radar needs a direct line of sight to something to be able to see it. This limits ground based radar to a range of about 60 miles. Major international airports will have radar that can see that far, but smaller airports - particularly those outside of the US - don't. Radar coverage throughout the world is pretty minimal. Civilian radars typically only cover a small area around airports while military radars only really cover the area around airbases as well as some potential conflict zones. Chances are that you're outside of radar coverage if you aren't flying over a major city. However, commercial airliners are all equipped with a radio transponder that is just constantly broadcasting the plane's current GPS coordinates and height. This allows airports to see where planes are far beyond the range of their actual radar. When a plane suffers some sort of catastrophic problem - such as blowing up in mid air, that transponder gets destroyed and stops broadcasting. This is what the media will typically refer to as the plane \"vanishing from radar.\" In other words, the plane wasn't actually being tracked by an active radar system, but it was showing up on an airport's radar system because that system is capable of detecting the plane's transponder signal out to a very long range and displaying the embedded positional information on the airport's radar screen. In the case of Malaysia Airlines flight 370, the theory is that the pilot turned the transponder off. If the transponder is off, then the plane will only show up on radar screens when it comes within that 60 mile range of an actual radar system that puts it close enough to be detected."
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bzq7px | Do wired earphones use less battery than Bluetooth? Why/why not? | Technology | explainlikeimfive | {
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"I think the power used to broadcast the Bluetooth signal is higher than what it takes for the device to power the wired speakers."
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bzr022 | How does a video game programmed in a PC get stored in a cartridge that can be played by a console? | Technology | explainlikeimfive | {
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"So ultimately what gets run on any piece of hardware is machine code, instructions that the chips on that hardware can understand. You can program in any \"high level\" programming language and then compile it, which means turning it into machine code. It's like translating from English to a region's local language. You can \"target\" a specific set of hardware, say a Nintendo Switch, by compiling specific machine code and making sure you meet certain limitations. Generally, developers who want to make games for a console can request to buy a dev unit from the makers, which is a system that has all the same specs as a normal console but are otherwise meant for ease of testing. They make sure that their games run well enough on the target system before publishing the game.",
"The code that is written on the PC is just words. When the game developer is ready to run the game on a console, the code is translated into a special machine code that the console can understand. Most of the time, the code will be sent to the console over a serial cable, rather than writing it to a cartridge and then plugging that into a console. When it comes time to put the game onto a cartridge, the developer will use a special device that can read and write to the cartridge. This works just like how you can write data to a USB drive.",
"Former game developer here, & #x200B; Older consoles had dev kits, hardware that interfaced with workstations for development. Even the old Sega Genesis, you could use the player 2 controller port as a D-sub serial port for debugging. & #x200B; You would write your code. For the NES, it was basically assembly, and the assembler would generate machine code you would flash to an EEPROM dev board, for the PS1, it had a pesudo-C compiler, later consoles from the PS2 and XB1 forward had C/C++ compilers. Hell, the XB1 and PS3 both used Power PC based processors. Later dev kits, you would just \"push\" the program onto the console and test from there. & #x200B; Now, not all code is platform dependent. Some aspects like game logic is not hardware specific, so you could write and test this code on your workstation. This sort of testing is called unit testing, and it's about proving consistency given some initial condition. I put in a 7, I expect to get a 22. Or whatever. & #x200B; Well, you're asking about cartridge based games. Old consoles relied on older technology. We didn't have NAND flash memory back then. We had EEPROM. You would have a dev cartridge with a programmable memory device, and an interface that would write to it through the cartridge. To erase them, there was a glass window on top you would expose to UV light. The more times you would rewrite this memory, the longer each subsequent write would take, until the thing physically wore out and wouldn't take the program. NVRAM, like what stored your saved game, DID NOT have the memory density to store an entire game, and was too fragile. & #x200B; In manufacturing, they would program banks of PROM devices at a time, before later being soldered to the cartridge board; it uses pulses of high voltage to fuse or burn links internally in the device, the consequence being the structure inside represents the data. All such ROM chips are writable once, and the programming legs on the chip are still there even in the cartridge. They won't do anything, and likely they're \"tied to ground\" so they are made to do nothing. I'm sure if you hooked that chip up to a writer and tried writing again, either nothing will happen, or you'd destroy the component."
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bzrpwg | Why is there so much clipping/ what causes the clipping in Bethesda games? | How come objects clipping though walls is so particularly bad in Bethesda games? It’s so prevalent that there’re memes about it and it’s present in almost every Fallout or Elder Scrolls game they’ve made. It’s so prevalent that my mind just filters it out now and I take it for granted. Question is why though. What about their engine makes that a thing. Most other AAA games from the past decade have solidly beaten clipping. Why can’t Bethesda stop it? And what causes it? | Technology | explainlikeimfive | {
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"The games are massive and open plan. Everywhere 2 sides meet is a potential point for clipping but due to the size of these games it is very labour heavy try to find all the clipping spots. Classic corridor games are much easier to debug for this because there is a much more restricted area that you can walk about on. Bethesda have a reputation for being lazy when picking these up but that might be unfair. I'm surprised we haven't developed AI for testing this sort of thing tbh as it is very menial work to sort through."
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bzt1vb | Why is it considered dangerous to use your device while the plane is taking off? What does Airplane Mode do to combat this? | Technology | explainlikeimfive | {
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"Takeoff and landing are the two most dangerous parts of flying; if the plane doesn't crash during takeoff or landing, it is most likely not going to do so in the air. But because planes carry so many people and a crash from even 100 feet up means that most of the people on that plane are likely to die, air traffic regulations don't fuck around. Theoretically, your cellphone shouldn't be able to fuck with air traffic control's communications, as the device is designed to not cause harmful interference, and to accept any harmful interference it receives; those little stickers that say that, those design constraints on consumer electronics, and that regulation, are all there specifically for air traffic control, by and large; their radios don't follow that rule: they will cause harmful interference if they have to, they will not accept harmful interference if they come across it. But despite the fact that it *should* be impossible to fuck with ATC's radios with the radio waves sent/received by your phones, because we are dealing with metal tubes pushing hundreds of humans through the sky at several hundreds of miles per hour, we don't fuck with \"should be\"; radios can't transmit harmful interference if they're off, so we have them turned off. Even if it's a 1 in a million chance that a cell phone could mess with air traffic control at all, and a 1 in a million chance that that interference will cause a fatal crash, there are about 2.7 million passengers flying commercially *per day* on about 87,000 flights per day. It might take a long time, but eventually over a long enough timeline, even 1 in a million becomes a certainty. It's the same reason that airplane bathrooms have ashtrays even though smoking isn't allowed; it's a failsafe; if the measure of telling people \"don't smoke on the plane\" doesn't work, and the smoke detectors fail, then at the very least there's an ashtray so that nothing flammable gets an ember (or it's a very low chance). You want to stack those probabilities as much in your favor as you can, because when planes crash, people die.",
"A pilot friend of mine was asked the same question about Airplane mode and he said \"It doesn't interfere with their radio at all\".",
"Take off and landing are the most dangerous parts of the flight and using your device can distract you from the situation if something goes wrong.",
"It isn't dangerous at all. They have you put away electronic devices because they could fly around and smack someone in the face if the plane was going to crash. Anything not strapped down is potentially a weapon at fast enough speed. Airplane mode doesn't really do anything, but we have an outdated boogeyman stigma that your phone could somehow interfere with the electronics in the plane and make it crash. Every flight you've been on in the last 5 years had at least one device not in airplane mode on it and ended up just fine."
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bzudkd | Why does minimizing some games increase GPU usage to 100%? | Technology | explainlikeimfive | {
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"text": [
"[V-sync]( URL_0 ) - when playing, and this setting is on, the game's frames per second are maxed out at 60, which is the maximum that the screen can display. When minimized, certain games continue to render the screen animations, but no longer limited at 60 FPS - they go to the max that the video card can handle."
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bzzogp | I set my truck clock ahead 3 minutes from my watch but I'm a couple weeks it's 4-5 minutes ahead. Shouldn't it just stay three minutes ahead? | I usually set my vehicle clock ahead too be early to places. I used to set it areas 5 mins but in a few weeks it'd be 7-8 minutes ahead. | Technology | explainlikeimfive | {
"a_id": [
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"Have you traveled over 88 miles per hour in your truck at any point over those weeks?",
"Most commercially available clocks aren't perfect at keeping time. This is obvious very quickly if your clock went by by one second for every two, or the reverse, but when it's off by a hundredth or a thousandth of a second it will take some time to show up. Your phone is linked to a system that gets it's time keeping off of some of the most precise clocks out there. You average digital readout click in a vehicle has no such link and was manufactured by a low bidder with the cheapest possible materials. It's not particularly surprising, then, when it turns out that it isn't quite as exact as you might like, and will slowly start showing the wrong (or in your case, more wrong) time. Also, your watch suffers from the same probl am as the vehicle clock. While it's accurate enough for most purposes, it can be off enough that it'll show over time.",
"It would stay constant if the clock in the truck was accurate but it look like i run a bit fast. A 2 minutes or 120s error in lest say 4 week is a error of 0.17s per hour or 1s per 5.6 hours. That is a error of 1s per 20160s an that is a lot. A typical quartz wrist watch have a error 13s per 30 days so you are off by a factor of 10. I suspects that the problem was the temperature but a regular quartz crystal slows down both when it is both to warm and to cold and yours is faster. So you have a clock in the car that either have bad component from when it was build or one where part have failed overtime . So you for it to be accurate you need to replace the cock or what part that drives in if it is a new car with a lot of builtin electronics."
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c00acb | Why haven't humans connected the Bering Strait with road or rail? | Technology | explainlikeimfive | {
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"text": [
"That bridge would connect Siberia with Alaska. Neither territory has the population to justify the cost of building the bridge. People in the US wanting to send things into Russia or beyond (and vice versa) wouldn't send it the long way around by truck anyway. They'd put it on a boat or a plane and just go more or less straight. And there isn't really a highway leading from the region around the Bering Strait in Siberia to anywhere in Europe either."
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c01og2 | How do animation movie studios sync voices to animation? | I always wondered. Do they record voices first, then animate around the voice? | Technology | explainlikeimfive | {
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"The easiest way is to record lines and then animate the characters to the voice. They do it this way so that the actors don't need to worry about matching any of the visuals. In a lot of animation studios, they actually film the voice actors recording the lines and give the footage to the animators. If you watch a video of Robin Williams recording lines for Aladdin, its easy to see how his acting had an effect on how the Genie was animated.",
"Different places use different techniques. Some produce the animation first and have the actors sync to visuals, some record the dialogue first and animate to match. Generally, Japanese animation is produced by the former method, while most western animation is done by the latter."
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c02qa2 | How does a bionic arm work? | How does the wearer control the fingers and movement with their mind considering it’s not their arm? | Technology | explainlikeimfive | {
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"Myoelectric prosthesis are connected to your body by electrodes on the skin or in the remaining muscles of the limb you lost. If you try to move your missing limb, your brain will still send an electric signal through nerves. The electrodes will sense and transmit the electric signals to your prosthetic arm whose electronic parts will « decypher » and make your prosthesis move according to what you wanted. But it gets better ! If you completely lost your arm, for example, your nerves that would have gone in your arm can be surgically re-wired to you pectoral area, so that when you « move » your limb with your brain, the information goes in your pectoral muscle, where the electrodes of the bionic arm will catch it. Technology is pretty sweet in the 21st century !"
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c05el8 | Why don’t car manufacturers make cars that seat 3 up front anymore? | I had a car long ago that seated 3 up front. Was very practical at times. Why don’t cars do this or even some with that option if ppl need? | Technology | explainlikeimfive | {
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"Seating 3 means a bench seat. Bench seats feel cheaper (and they are) and they're less comfortable. People want bucket seats that adjust 10 different ways. And without a center console there's less room for cupholders and phone chargers.",
"“Bucket seats” used to be a selling point for particular models. People don’t want bench seats anymore. Car manufacturers aren’t in the business of making things people don’t want.",
"It's a combination of factors: people are bigger, safety rules are stricter (ie 3 point seatbelts), cars are smaller, families are smaller, ... Car companies make more of what people buy.",
"Trucks and utility vans often do have the option, but it's not as comfortable so most people don't want or need it. From a manufacturing standpoint it's not cost effective to offer that option for regular cars because it's a lot of effort and redesign for regular cars but so few people would want it."
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c05f91 | What exactly is the Google Stadia? | Technology | explainlikeimfive | {
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"text": [
"Stadia isn't really a thing it's a service, some people describe it as Netflix for video games. You'll need to buy the controller from Google and pay a subscription fee and it will let you play video games without a console over the internet. Apparently you can play on any Chromecast enabled device, so a computer or TV with Chromecast will work equally as long as your connection is fast enough."
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c062ho | Why phone and laptop companies still use Li-ion batteries? | I've read about quite a few (new) battery technologies but why is it that companies don't try to implement those rather than just keep increasing the mAh of the current Li-ion batteries? We all know those degrade with time and there are some methods which are far better. | Technology | explainlikeimfive | {
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"They’re all still in the development stage- not yet possible to mass produce efficiently, meaning they’d be quite pricey",
"Li-ion batteries satisfy the device makers’ requirements, including power, reliability, lifespan, weight and size, and cost. Other technologies might outperform Li-ion in one or more of these metrics, but Li-ion performs best if you consider the makers’ requirements as a whole. This could change, through technological advances, or through changes in what consumers demand and thereby in the makers’ requirements.",
"Cost, mostly. New technologies come with new factories and new investments that have to be made, so the early products cost much more than the older technologies. If there isn't enough of a difference in size, weight, or performance that the companies could use as a selling point to justify the increased cost, switching is a bad decision from a business standpoint."
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c06xu7 | What exactly do Nvidia developers update when they release drivers for a game? | Every now and then, when a new game comes out, Nvidia (and AMD) come up with updated drivers that supposedly improve the performance of the game. But I've always wondered, what it is that they update? Are they simply adding game-specific behaviour for the graphic card or ar they modifying some "system-wide" property about the drivers to accommodate for the game's needs? | Technology | explainlikeimfive | {
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"text": [
"Former game developer, & #x200B; Driver developers work with studios to develop custom driver profiles so those games run optimally. Often enough the studio is doing the wrong thing, and at that point in development, it's often easier to fix it in the driver than tell the studio to do something right."
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c09nyw | Why don’t you need to wear a seatbelt on public transportation? | Technology | explainlikeimfive | {
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"text": [
"For one thing, busses are much heavier than cars, so in a collision they will usually experience much less deceleration. But if you drive into a tree or wall that won't help you.",
"Overall buses are safer than cars. Buses have professionally trained drivers. Buses go slower than cars and stop often, so not an opportunity to get to the higher speeds of cars. Also the bus is much larger than a car so the inertia reaction of an accident would be much less to a bus hit by a car than it would to a car hitting another car meaning that you would not get thrown around inside of the bus if a car hit it . The impact would be absorbed by the larger vehicle better. These are generalizations, knowing that there are many exceptions to these so this is why many newer buses now have seat belts."
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c0etee | how is it possible people can create things like working internet and computers in unmodded Minecraft? Also, since they can make computers, is there any limit to what they can create in Minecraft? | Technology | explainlikeimfive | {
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"Minecraft provides the fundamental elements required to build a computer: circuits (wires), logic gates, memory and a clock, as well as mechanisms for input (programming) and output. With these basic building blocks you can theoretically simulate a functioning computer, though there are practical limits to how easy it is to build it and how fast it can process instructions.",
"there is a whole part of mathematical logic called \"computability theory\" that describes how one thing can be computed from a set of (base) elements. There is a (somewhat sloppy) definition called \"turing complete\" which basically stipulates that if you can create a very specific type of \"super basic\" computer called a Turing Machine, you can use that as a building block to create any other computer you want. Minecraft is turing complete, so you can theoretically build any type of modern computer from/in it. [ URL_0 ]( URL_1 )",
"Any machine that's considered \"Turing complete\" can simulate any other such machine. Generally, most computers will roughly fall into that category with the right language or platform that acts as one. You can build a smartphone in Little Big Planet. It just wouldn't be very useful. The practical limitations are things like: - the capacity of your storage media - the performance of the virtual machine - the difficulty in writing this machine etc.",
"There is a limit, as Redstone blocks use a software simulation of a binary switch, which in and of itself takes processing power more than a single transistor gate on a processor. Thus, the only limit to what can be made in Minecraft would be the power of the user's PC. & #x200B; I assume at some point you'd probably break Minecraft too by making it do too many things at one time. & #x200B; Also, since it's a person making them and not a machine(I would imagine anyone that can make things like these could probably automate the process, but I don't know, and not to the extent that a laser can make transistors), building millions or even billions of Redstone circuits is not viable, thus it will remain at relatively simple computing, and not complex 3D graphics or anything.",
"Computers are basically lots and lots of switches, on for 1, off for 0. This creates binary, with each digit referred to as a \"bit\". Knowing this, and with knowledge of how binary works, you can create a length of switches to do the same thing.",
"In theory you could create a functional microprocessor, but clock speed would be an issue. Basic logic gates are easy to create and you can expand from there. World edit would certainly speed things along.",
"the limit is the chunk limit. minecraft loads visible terrain in chunks, based on how far your render limit is set. even at the farthest settings, with the world stripped down to nothing but redstone circuits, you won't get nearly enough space to do anything approaching what we consider a crude computer, let alone anything modern. basically, minecraft only activates what is in sight range, and at the widest setting steve can't see far enough.",
"You could in theory build a working computer from almost anything. The only problems you get when not using microelectronics are size, low speed and energy consumption. All you need is a basic element of a switch that can turn on other switches. The first crude computers were built mechanical, and then with electromagnetic switches. But you could make one with pressure opened valves and make a water or steam computer.",
"Does this mean someone could create a minecradt universe inside Minecraft?",
"maybe we are just one instance made in minecraft?",
"A computer is made of power. Power can only go on or off.This explains all the 0's and 1's you see, something is either on/off, and thats how hardware in computers work & #x200B; This is the same case for redstone in Minecrafteven though redstone can have a pulse from 0 to 15 (where 0 is off) people make mostly use of it of the fact that its either on or off (pulse on 0 or above 0) & #x200B; So what they do is they build hardware circuits thats similar to reallife computers which then can do certain operations, like basic calculations & #x200B; You can notice however these computers are pretty slow inside mc, but that is because your computer's hardware is running software that simulates hardware that has software. Regarding the limit: The blocks and redstone that has to work, has to be loaded obviously so that depends on the load distance (which differs per PC, as an higher load distance requires a better computer)",
"Even the most complex, advanced red stone computers are completely outclassed by irl pocket calculators."
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c0j98q | Why can't we truly delete pictures and documents from a cellhpone or a computer ? | Not long ago I had to factory reset my computer because it had some problems. After the reset I managed to get my pictures and documents (I don't remember if I recovered all of them) back using a recovery software. I even recovered pictures that were deleted prior to the reset. Something similar happened with my cellphone. Why is that ? Why can I get the pictures/documents back when they are supposed to be gone forever ? | Technology | explainlikeimfive | {
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"Computer storage is designed to be stable for a long period of time. Some technologies, like flash memory, have a limited number of changes and a long storage life. When you \"delete\" something, the storage is just marked as \"unused\". Actually erasing it is bad for 2 reasons: a) it takes more time, and slow is annoying; and b) it might shorten the life of some storage. When you fill the storage back up again, those storage blocks are filled with something new. Until then, they just sit there with their old information. Recovery programs read through this \"unused\" storage, looking for the patterns that define file structures it recognizes. When it finds storage blocks matching the pattern, it can restore, at least part, of the file. You can get a \"security erase\" program that erases the blocks before it deletes the file, it's just not the default behavior.",
"Deleting things normally doesn't delete the data itself. It simply removes the index for it. If you imagine your memory is a library the books wouldnt be kicked out, they would just get removed from the catalogue. The space is declared to be free and can be used by anyone, but often you are lucky and the exact memory locations aren't overwritten later. If you try to get rid of data for good, things get more complicated. You can overwrite the former places of data with random numbers, but even then there will be hints left in the memory so a skilled person can recover some information. Even demagnetizing your harddrive isn't completely secure. Harddrives with sensitive data are actually completely desintegrated to leave no clues behind.",
"You can fully delete documents from a computer, it just takes more time and effort then we're normally interested in taking. To create a file you need to write every byte of it to the HDD, SSD or SD card as well as create an entry in the file system (think of it like a hidden index file) saying where the file is and reporting that the area of the disk it's in is now in use. However to delete a file all we normally do is erase the entry in the file system. The contents of the file are still there (until something else overwrites them, since that area is no longer claimed) but as far as the OS is concerned the file is gone in an instant and the drive is ready to perform another operation. You can get software that will 'shred' files by overwriting them completely with zeros before marking them as deleted, though this shredding process gets complicated with SSD storage due to wear leveling."
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c0jb1k | How does a Nintendo 3DS produce its 3d effect? | Technology | explainlikeimfive | {
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"It has two screens on top of one another and the light projects at different angles to trick your eye into believing it’s 3D. If you move the 3DS too far to one side, the effect will disappear.",
"To be a bit more specific, there is actually only one screen, but each vertical column of pixels represents alternate columns of the left and right eye. On top is a lenticular lens, which angles each alternating column to the eye meant to receive it. The difference in the view each eye receives is what your brain interprets as depth. The Virtual Boy worked in a similar fashion, but used two separate displays to produce the same effect."
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c0jeke | what is Synchronous Data Link Control (SDLC) ? | Technology | explainlikeimfive | {
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"text": [
"It's an old way for devices to talk to one another through wired connections, created by IBM and pretty much only used by IBM. At one point, there were a lot of competing standards (SCSI, Ethernet, Econet, Token Ring, LocalTalk, RS-232, IEEE 488), but most of these standards have died out, and most devices today talk to each other using Ethernet, or new standards like Wi-Fi (802.11) or ZigBee. SDLC lives on in a small niche of connecting industrial devices and sensors to their controllers, as part of the BITBUS standard."
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c0lmxt | How does a SSD read data quicker then a HDD. | Technology | explainlikeimfive | {
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"text": [
"An [SSD]( URL_0 ) has memory chips inside, so \"reading data\" is just a matter of the electronics inside the SSD to find where in memory that data is. A [HDD]( URL_1 ) stores data magnetically on platters (disks). Sort of like magnetic CD's. Reading data involves moving an arm with the magnetic heads to the position on the disks where the data is, and then reading it. So even though the robotics inside a HDD are pretty fast, physical movement is still much slower than electronics speed."
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c0o20x | How do marketplaces (e.g. URL_0 ) handle currencies? | For example, anyone can view hotel rooms in their local currency, and the hotel would post their rooms in their local currency.. I'm assuming URL_0 save the price in the hotel's currency, then convert it for the end user.. but when you book, does the transaction get saved in the end users currency? And would that not be a problem when the hotel gets paid? E.g if I book a hotel in the us in GBP and then choose to pay on arrival, do I pay in the exchange rate when I booked or the exchange rate at the time I made the payment? | Technology | explainlikeimfive | {
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"> And would that not be a problem when the hotel gets paid? No. URL_0 's bank and the hotel's bank would work it out so that the hotel gets paid in their preferred currency. & #x200B; > I book a hotel in the us in GBP and then choose to pay on arrival, do I pay in the exchange rate when I booked or the exchange rate at the time I made the payment? On arrival. When you make that reservation, URL_0 would promise the American hotel a certain amount of USD. You would be responsible for paying them that much USD, regardless of exchange rate fluctuation."
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c0okbk | How does a battery continue to support the exact same functionality as the charge decreases over time? As in with a phone battery, how does the screen not get slowly dimmer, sounds from the speakers quieter? | Technology | explainlikeimfive | {
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"First of all, I'll make a slight correction to your question: \"maintain the same amount of voltage as the amperage decreases\" Actually, it's quite the opposite. It's the **voltage** that decreases as the battery is discharged. The current (amperage) mainly depends on what is connected to the battery (what we \"demand\"). And the voltage can have some dramatic drops when the battery is discharged, from 4V to 3V (25% less), or even from 4.2V to 2.7V! (35% less) Normally, this would be quite noticeable, as you correctly imagined when you asked the question. & #x200B; So, in order to avoid this effects, there is an extra circuit in the devices. This circuit maintains a fixed output voltage, independent of the input voltage. This is called a buck-boost, or step down-step up. This circuit works by converting the input voltage (whatever it is) into the output voltage just like a Transformer does. The only rule you have is that Power in = Power out (+losses). & #x200B; As an extra: Electrical power is calculated as P = I\\*V, where I = current and V = voltage.P(in) = P(out), so V(in) \\* I(in) = V(out) \\* I(out)This would mean that as V(in) decreases, I(in) must increase in order to keep the total power (brightness of your screen) fixed. This would mean that the current (amperage) actually **increases** as the battery discharges.",
"Imagine a tank full of water, and you're draining the water from it. As the water level drops, so does the pressure, causing the flow of water to become slower. So what you can do to remedy this is to squeeze the tank to maintain a steady flow of water, to compensate for the loss of pressure. All modern electronics have what is called a boost converter in them. This converts the varying voltage of the battery into a stable, pre-defined voltage. This comes at a cost though: the current (amperage) drawn from the battery will increase, as the boost converter draws more and more current from it as the voltage decreases, to compensate. But that's fine, it only means that the battery will drain faster when the voltage starts to drop, but your phone will always receive the same amount of power until the battery cuts out.",
"A voltage regulator is what helps set a constant output voltage to a circuit given variable input voltage (batteries). The cleanest method is with a linear voltage regulator that takes a higher voltage and produces a fixed lower voltage. Clean electricity is necessary for precision circuits like the CPU in your computer. Even if the higher voltage starts to decrease, the output will remain constant up till the input drops too much. The downside of linear regulators is that they drain power to run so they reduce the overall usage capacity. Other voltage regulators like switching regulators can take a lower voltage to produce a constant voltage than can be higher than the input. These are used in the case of AA batteries where alkaline vs lithium batteries have big differences in their nominal voltage (1.5 V vs. 1.2 V respectively). the regulayors can draw power even if the battery voltage drops a great deal. The overall circuit may have a fixed cutoff to prevent draining the battery too much. The downside of the switching regulators is that the act of boosting the voltage adds electrical noise to the circuit. They cannot be used for sensitive applications."
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c0opny | How do these computers work at a library where you put stacks of items on a shelf and it automatically checks them in or out without scanning barcodes? | What witchcraft is this? No barcode scanning and I've done up to 5 at a time no problem. Image for reference: URL_0 | Technology | explainlikeimfive | {
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"RFID. The books have a thick sticker, probably in the back cover, with an antenna programmed to that book. The shelf reads those tags. Source: worked in library that made the transition to those tags. Tagged several thousand books.",
"I helped install one of these once! It is called RFID: Radio Frequency IDentification. Each book has an electronic sticker in it. At our library, this was a long, thin, flat strip that is inserted down the spine. Others just have it placed on the rear cover. There are also stickers for CD's too. Inside of this sticker is a little computer chip, and a little antenna. When you place the sticker over the RFID reader, the antenna receives a signal. This signal is converted into electricity, which powers the chip, which has a barcode number stored in it, and then the antenna emits that barcode number as a radio signal. The RFID reader then receives the reply, and can use the code to look up the item just like it scanned a barcode. Depending on the library, the RFID reader might be a plate on which you place the book, a wand you wave in front of the book, or it might be built into the shelf. ======= This creates some interesting problems. 1) If you stack too many items on the RFID reader, then the reader has trouble detecting all of them. It might misread a code, or fail to get a code at all. 2) If you place a thin piece of metal over the RFID sticker, both the front and the back, then it can't be read at all. Not even by the security gates. That caused a lot of problems at our library... : ( 3) If you have RFID readers too close to one another, they interfere with each other and mess up in all sorts of weird ways. 4) If you have metal too close to an RFID reader, it can act as an antenna and garble the signals being sent/received. Effectively, it stops them from working properly."
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c0pqhb | Why is it we can play mega-ultra HD on COD at 120 Hz without a hitch, but can't explode 100 TNT on low poly minecraft without freezing the computer? | Technology | explainlikeimfive | {
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"Because COD is a relatively simple game (as far as computer calculations go) and all you really need to do is render the game. There's no physics that need to be processed, since everything is a prerendered animation. With 100 TNT blocks, you need to calculate the force being applied to each TNT block each time another explodes, and calculate where it's going to go for each frame displayed. This will cause an increasing amount of RAM to be used for storing these calculations, eventually leading to the system slowing down or freezing. TLDR: mega-ultra-HD COD is basic graphics rendering, while TNT in minecraft is lots of big calculations that need to be done before the rendering.",
"I don’t know the specifics about Minecraft but I’d say it wasn’t optimized for that. Do you know the trick that when you multiply something by 11 you just add the first and last digits and you get the middle digits? So 12 * 11 12 Add 1+2 and put the answer in the middle 132 is 12*11 511*11. (3 digit numbers are slightly different) 511 51 + 11. =62. Smash that between the left and right 5621 Now you know this trick of how to do this function faster than traditional multiplication by hand. It has been optimized. Minecraft is old math by hand. Cod is optimized."
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c0pr37 | Why do full frame DSLRs deliver optimal performance at ISO 100 while many digital cinema cameras with smaller recording areas perform best at 800? | Technology | explainlikeimfive | {
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"It's easier if you think about this the opposite way around — let's imagine we're designing a video camera. You rarely want to use a super-wide aperture for video, because you need the depth of field from a tighter aperture, so you lose out on a tonne of light from there. The usual rule of thumb is that shutter speed = 2x frame rate, so you're going to be shooting in the 1/60\"-1/50\" range, or thereabouts. Not crazy fast, but not super slow either. Given those limitations on shutter speed and aperture, you're never really going to be filming at ISO 100. Something at or above 800 is much more likely. So now we're going to design the sensor. There's nothing special about ISO 100 that makes it particularly appropriate to target that as your base ISO, and you know you don't need to handle low ISOs but need good performance at higher ISOs. So you design the sensor from scratch around a much higher base ISO. The important point here is that the video camera won't produce an image at ISO 800 that's anywhere near as good as the photo camera will at ISO 100 (given appropriate shutter speeds and all that), and won't outperform a larger sensor built on similar tech either. Rather, the video camera designed around base ISO 800 will produce a much better picture at ISO 800 than a photo camera (with a similar-sized sensor, but designed for ISO 100) will produce at that same ISO 800.",
"ISO is roughly equivalent to digital gain, so lower ISO means lower noise, as the signal is less amplified, and so is the noise which comes from the scene because counting photons is a noisy process following a poisson distribution... It's possible though that the thermal noise might keep roughly constant or very small for some cameras, but this is way smaller than shot noise IMHO. And finally dslrs may have older sensors but their effective area is wayyyy bigger so they always capture more photons. What's your criteria for having \"better performance\" at higher iso?"
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c0qc6a | How does the Hubble telescope, moving 8 km/s around the Earth, take clear and well exposed pictures of interstellar formations light years away? | Technology | explainlikeimfive | {
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"When you're driving down the highway, the bushes right on the side of the highway appear to be zooming by at incredible speed, while the mountains in the distance dont seem to be moving at all. This is an effect called parallax. Now imagine how incredibly little the interstellar formations would seem to be moving when they are many orders of magnitude further away. All the telescope needs to do it slightly adjust its angle to stay pointed at the right spot."
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c0rhr2 | Why are house arrest bracelets placed on the ankle instead of the wrist? | The ankle seem’s like an impractical place to put it, but obviously there’s a reason. What is it? | Technology | explainlikeimfive | {
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"You can’t contort your foot/ankle the same way you can your hand and wrist. It makes it very difficult to get off without resorting to more extreme measures.",
"Where would you to have a bracelet of that size on your body for week at end. Where would it be most in the way? It has to be so tight around so you can slip it off and it would be tighter around the wrist. The first model I found online had a mass of 8.7 oz( 250g). Put a object with that mass on either location and determine where you would like to where it. Where would you like to have it your ankle of your wrist? I suspect that answer is the wrist and for obvious reasons."
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c0t22a | How do devices like weight scales and body fat measuring machines figure out the percentage of things like muscle, fat and water in your body? | Technology | explainlikeimfive | {
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"The scale detects water by putting a voltage across your feet. Because stuff dissolved in water conducts electricity, the more water you have, the more current makes it through. Fat requires the scale to know your height. The scale just compares your actual weight to the weight of a person as tall as you, but with pure muscle."
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c0un2w | How can I access and stay connected to WiFi while inside an airplane thousands of feet in the sky? | Technology | explainlikeimfive | {
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"text": [
"A satellite beams Internet to the plane which has routers and access points. It also acts as a mid-point for whatever information you send to the Internet. Ground based antennas work too, if they're available."
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c15wgx | How do activity trackers know when I'm asleep? How they deduce REM sleep, deep sleep etc? | Technology | explainlikeimfive | {
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"They detect movement through either an accelerometer or by using a microphone to listen out for movements (as programmed by the software). Since each sleep cycle lasts roughly 30 mins, the tracker is really only guessing which stage of sleep you are in based on the time in bed and any movement detected throughout the night."
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c16a2n | Why do some companies create multiple apps for the products they offer instead of using one app? Uber and Uber Eats, Google Home and Google Assistant are two examples. | Technology | explainlikeimfive | {
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"Marketing. You get more people to use your app/product if you have different versions targeted to specific groups. It's why there a separate varieties of cold medicine in spite of all of them having identical ingredients. If presents with a choice between something generic and something that seems tailored to their specific needs, people will choose the specific one most of the time, even if there's no actual difference."
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c174d0 | what is the difference between Ark, Mig, Tig, and Oxy Acetylene welding. (?Strengh, speed, efficiency?) | Technology | explainlikeimfive | {
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"Hello there! I want to start off by apologising for how long this post is; I didn’t want to oversimplify it too much. Both MIG (metal inert gas) and TIG (tungsten inert has) are forms of arc welding. TIG may also be referred to as GTAW (gas tungsten arc welding) and MIG as GMAW (has metal arc welding). Typically when I hear arc welding, I think about SMAW (shielded metal arc welding) or stick welding, which is one of the most common welding processes. However, I have also seen FCAW (flux corded arc welding) referred to as arc welding. All of these processes have a few things in common however; they all use heat generated through electrical resistance and all utilise some form of atmospheric shielding. MIG and FCAW work almost the exact same, as both utilise a wire feed mechanise that feeds the consumable wire electrode into the weld pool. However, MIG uses an external shielding gas, which is typically either carbon dioxide (CO2) or argon (Ar), which is dispersed through a nozzle over the weld pool. FCAW, however, doesn’t use an external shielding gas. Instead, it uses a hollow wire which inside contains what’s called flux, which burns and creates a shielding atmosphere for the weld pool. Both of these processes are fairly quick to use and easy to learn. However, they cannot weld aluminium and cannot weld very thick metal. My FCAW machine can only weld up to 3/16” metal, however, I surmise there are other, more powerful machines that can weld thicker materials. TIG welding is a little bit different than GMAW, as unlike these two processes, TIG uses a non-consumable electrode that is made out of tungsten and mostly uses Argon as a shielding gas. This makes TIG a very precise process; it can be used to weld needles together. The TIG process is more difficult than GMAW as the welder not only has to direct the arc, but they also have to manually feed in the filler rod by hand into the weld pool. However, as a result of the precision this process has, it will produce the best looking welds out of all of the processes. The most important aspect of TIG is that it can be used to weld aluminium, and to my knowledge is the best method for welding aluminium. This process isn’t very fast to do, and is difficult to learn. SMAW was the first arc welding process to be used. SMAW or stick works by having a clamp, which holds a long thick wire, which is why it is called stick welding. This electrode is coated in flux, which makes this process gas free. What the welder does with this process is strike the arc like a match, and pull the electrode across the joint or whatever is being welded. While pulling the electrode, the welder also pushes the electrode down, as it’s consumed during the process. This can made the process difficult to learn, however it is one of the most versatile processes. SMAW can be quick and efficient as its basically a strike and go process. Oxy/Acetylene or Oxy-fuel welding is the only process here that doesn’t use electricity. Instead, acetylene and pure oxygen are combined and burnt to produce heat and a protective flame envelope. With this process, the welder also has to feed the filler rod by hand. However, Oxy-fuel is a much slower process since you have to wait for the metal to heat up and melt. This makes this process the slowest out of all of the aforementioned processes. That being said, this is the most portable process since it doesn’t require an electric current. I wanted to wait until the end to touch on the actual strength of all of these processes. Assuming you’re making good, correct welds, all of these processes can produce strong welds. This means that the only real limitation will be the thickness of the metal itself. Because of this, i would say that SMAW is probably the strongest process since it can weld the thickest metal out of all of the other processes."
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c18yux | how do new barcodes get made? How do companies make sure their product doesn’t have the same code as a different company when it gets scanned in the shop? | Technology | explainlikeimfive | {
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"Barcodes are actually just a font what represent the numbers that are normally printed just below it. The most common type of barcode is the UPC (Universal Product Code) that is owned and managed by [GS1]( URL_0 ). GS1 officially licenses barcodes for products for sale, using a system where the first N numbers of the code represent the manufacturer of the product, and the rest represent the product from the manufacturer. By sticking to this system, and making sure that their barcodes use the correct manufacturer number, they can know they wont be overlapping with another manufacturer. Manufacturers can also pay more to get a shorter manufacturer code, so that they can have more digits left over to have more products.",
"Side note, but barcode scanners actually scan the white space of the barcode. The black lines are there to create the white space",
"A barcode simply represents a number. The left part of that number is the manufacturer code, while the right part of the number is the product code. Since no two manufacturers have the same code, there's no chance of confusion.",
"There’s a really good video by WendoverProductions/Half as interesting covering this with visual info here: URL_0"
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c1abiu | How are amputees able to control the fingers in their bionic arm ? | Technology | explainlikeimfive | {
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"The company I work at actually exclusively works on this! /u/WashingtonFierce post is incorrect, we do not yet have commercial technology designed specifically to physically interact with the brain and detect limb movement. The amount of time, money, and risk is prohibitively monumental. Imagine being an ethics review board member having to review an experiment about splitting a subject's head open to insert a sensor that you may or may not know will work effectively and reliably unless you try. /u/TheLazyD0G has more or less explained it correctly, and I can add some additional info. * Your brain sends signals to nerves in the arm, and the nerves are connected to the arm muscles. What actually happens when your arm muscle contracts is a bunch of sodium and Potassium ions moving about the cell walls of your muscles. Since these ions have positive charges to them, their movement generates a very very tiny voltage. The two sensors that sit in the prosthetic socket and touch the forearm are sensitive enough to pick up this change in voltage. This concept is called [EMG]( URL_2 ). * [So depending on the voltage change, the sensors can detect how hard you're flexing, or even at all.]( URL_0 ) * [The way the hands are programmed are in that they cycle through different pre-set grip modes, and the patient can only open and close them in the different modes.]( URL_1 ) The bebionic3, for example, you start out in Tripod grip (so you only close index, middle, and thumb) and can only close and open in that formation. You have to press the button on the back to change to Power grasp, and then you can only open and close them in a fist. You then have to press the button, AGAIN, to go into another grip, say Precision grasp, and then you can only open and close the thumb and index finger together. In a sense, they're just hand-shaped swiss army knives. * The patient opens and closes them by flexing their limb in one direction or another. Imagine flexing your wrist towards your chest. That's close. Now flex your wrist away from you. That's open. * This can get tedious (how many times did I have to press the button?) and can get frustrating if you make a mistake in a high-pressure situation (e.g. getting change into your wallet after the cashier hands it to you) * The pattern recognition that /u/TheLazyD0G mentions attempts to use multiple (3+) sensors and machine learning to have the arm change the grip based on which hand gesture you trained it to do earlier. However, this concept is still bogged down by the hand's programming of only changing between different pre-set gestures. * We have not yet achieved the level of fineness in detecting individual finger movements, largely to the concept of \"Crosstalk\". With the current size of these skin sensors, the region of muscle they observe can't distinguish whether a movement was for one finger versus another. Implantable sensors can theoretically solve this issue, but research into them so far have been very preliminary. Let me know if you have other questions!",
"Conventional myoelectric prostheses, what 99% of the bionic hands on the market use, are controlled by two inputs. Two sensors on the forearm (in the case of a below elbow amputee) pick up muscle signals. The amputee can either open or close the hand. Programming in the hand and using a variety of combinations of input codes can trigger different grips. For example, triggering open and close at the same time can engage one grip. Holding an open signal for a fixed time can trigger another grip. Sending a very fast/strong open signal can teigger a third grip. Same with a close impluse. With practice, it can become somewhat natural. Pattern recognition uses many more electrode sensors to pickup more fine movements that can directly pickup more detailed inputs from the remaining muscles, but it still is not at the individual finger control level yet. To control 5 individual fingers of flexing and extending. You need 10 different inputs. This level of detail is only possible with inplanted electrodes. To control every joint of each finger like you can with your natural hand, you will need about 35 different inputs.",
"None of y’all ELI5. Either that or your 5 year olds are are intellectual prodigy. Ahem... NERVES AND WIRES. We control our fingers with NERVES like we control most things in our body. Nerves are like wires that go down our arms from our brain to our fingers in a bundle. If we loose an arm by accident, the wires are still in our arm bit we still have, they just don’t go to any fingers anymore. The best doctors find the out these finger control wires... nerves... and make them go to the arm muscles on the arm bit that we still have instead. Now when we think of moving our fingers, our arm skin moves instead, just a little bit. They make the robot arm scan the real arm where the wires have been put by the doctor to move the skin! The cup bit where it attaches has the sensors. When the robot arm senses the arm skin make a move, it moves the robot fingers instead! They swap the lost human wires in the arm with robot WIRES! EDIT: Thx for the gold stranger! First one! I need to find the ELI5 for what it means now...",
"Depends on the exact type of bionic arm; but in general, the bionic limbs got sensors somewhere in the body (sometimes at the stump itself, sometimes elsewhere in the body) that measures either muscle contraction or nerve/neuron activity directly and interprets the different signals into limb position or movement velocity. Some variations are more intuitive to control than others, but in general over time the person learns how to control it with a bit more dexterity."
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c1buz1 | How big is the internet? Can it be define in GB or TB? | Technology | explainlikeimfive | {
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"Bigger. It's on the order of 1000 of petabytes. And growing. A petabyte is 1000x terabyte",
"Big can mena a lot of number of stuff. How many computer or humans uses it. The amount of data stored on public servers, the amount of transferred data over hen internet. All can be measures of how big is is. On [ URL_0 ]( URL_0 ) you ca see estimation of a lot of number that you might care about.",
"It depends on how you define \"the internet\" and what you want to measure. Internet is not only web pages (this is the *world wide web* or *web*) but online gaming, video and audio streaming (entertainment or calls), emails, file sharing, etc... Do you consider what's public only or not ? Meaning if I send you an email, it's not public (it's between you and me) but it's still \"belongs\" to \"the Internet\" ? And what's the time frame ? Everything that has ever been created and stored ? Maybe only in one second ? And what about content that have been deleted ? Indeed it's pretty hard to define where the boundaries of the Internet are. Like are Reddit's servers \"in the Internet\" ? Or not ? Or only those which are public-facing ? Or maybe no servers but only their routers ? There is a lot of things to take into account. Either way, I think it's measured in [Zettabytes]( URL_0 ) or even more (depending on what you take into account). Here is some numbers from that Zettabyte wikipedia page : * As of 2009, the entire World Wide Web was estimated to contain close to 500 exabytes, or half a zettabyte. * In 2012, U.S. Americans accessed already 6.9 zettabytes of data per a 2013 study. * In 2013, one expert estimated that the \"amount of data generated worldwide\" would reach 4 zettabytes by the end of the year. I probably brings more questions than answers but your question is too open to give you a clear answer. And even it were more precise, as you see, it's pretty hard to establish boundaries... P.S: Sorry for my english, I'm not english native. I hope it still bring an acceptable answer to you :)",
"Honestly.... No. The internet cannot be quantified into a size because any number given is immediately out of date. Sites are constantly growing, new sites are being created, and old ones are being recycled, taken down. The entire internet is thousands, if not millions of TB, and always changing."
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c1ehj3 | Why do some tail lights appear to flicker in dashcam videos? | Technology | explainlikeimfive | {
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"Old filament lights won't do this, modern LED lights will, the brightness of the light is varied by switching the supply on and off rapidly the on time and off time can be varied, the longer it's on the brighter the light, this switching happens at something like a thousand times a second, the human eye can't detect that flicker but the dash cam has a frame rate that, although different from the LED flashing speed, will occasionally syncronise and capture several frames when the LED is off. It won't capture the same off event but just a series of different ones but it allows you to see the flashing, it is called aliasing, and it happens with digital sampling of many different types of signals.",
"I am by no means an expert so this can suffice until someone more knowledgeable comes along. As I understand it, the lights on a car are in fact flickering (strobing) at a certain frequency, relative to the engines power. So, if the dash cam’s frequency is close to, but not the same as, the frequency of the light (on the car) then you will notice it flickering on video."
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c1eomx | How do flight computers in planes know how high above the ground they are. | Technology | explainlikeimfive | {
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"So there are a few ways. - Barometric altimeters measure the atmospheric pressure outside the plane and use that to (fairly accurately) estimate the height above sea level. This works because atmospheric pressure drops at a predictable rate as you increase your altitude, but because air pressure in a region can fluctuate you may need to adjust for local conditions. This gives you your elevation above sea level, so you have to calculate your height above ground based on your exact location. - Radar altimeters bounce radio waves off the ground beneath the plane and measure the time it takes for the waves to return. Since radio waves travel at a constant, known speed, you can measure your height above the ground this way. - GPS altimeters use satellites orbiting Earth to pinpoint your exact location, in three dimensions. They work on a similar principle as radar, but instead of measuring your distance to the ground, they measure your distance from three (or more) satellites. If you know the location of the satellites and you know your distance from them, then you know your location. This, obviously, gives you your altitude. Different planes may use one, two, or a combination of all three of these to give an accurate and reliable measurement of altitude."
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c1f1iv | How does Air Conditioning work? | Technology | explainlikeimfive | {
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"A compressor takes electrical or mechanical power and uses that to compress a refrigerant gas. That gas is then released into a series of coils where it can expand in volume. That expansion causes the gas to become very cold, which makes the coils very cold. Air is blown over the cold coils, which cools the air. The cool air is then blown through ducts to cool the building/car/whatever.",
"Air conditioners *do* use chemicals to cool the air, but it's a change of state and not a chemical reaction that make this occur. Freon is a rather popular chemical used in ACs, and this is first introduced into the system as a gas. The chemical of choice is condensed into a liquid form, creating pressure and the desire to be gaseous again. This chemical is then reintroduced into a low pressure chamber, where it wants to expand. This expansion requires energy, which comes from the heated air that is brought into the system from outside, or possibly inside based on the setup. The expansion of this chemical sucks the energy from the air to expand and revert to a gas form, and the rest of the system takes the cool air and circulates it through. This isn't a perfect explanation, and more information can be found [here]( URL_0 ) Edit - It's also worth noting that the chemicals that are chosen for this, stay cold in this system, but would rather not outside of it. Its like freezing water with pressure, the gasses are kept cold because of the environment they are in. After heating the freon, or other chemicals, the gasses pass through radiators to transfer that energy outside of the system, to be cycled through again."
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c1fbg2 | How do geiger counters work? | Technology | explainlikeimfive | {
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"They are chambers filled with a special gas (Boron Triflouride) that interacts with high energy photons and neutrons by releasing electrons. These electrons are attracted to a positively charged center rod in the chamber, and as they accelerate towards this rod, they create secondary reactions in the gas, releasing more electrons. When this large group of electrons hit the center charged rod, it created a momentary difference in voltage which is interpreted in the circuitry as a count and moves the needle on the Geiger counter a bit."
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c1gqbp | Why do photos of stripes/patters get all messed up on computer screens? | Technology | explainlikeimfive | {
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"text": [
"Do you mean moire patterns? URL_0 In television and digital photography, a pattern on an object being photographed can interfere with the shape of the light sensors to generate unwanted artifacts."
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c1hgh2 | How does vaporized liquid (specifically from electronic cigarettes/ vapes) not burn you? | Title says all. How does vapor from e-cigs not burn you when steam from boiling water can cause blistering? | Technology | explainlikeimfive | {
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"vapor is not steam. if you filled your vape with water it would probably burn you, and vapor can be uncomfortably hot around the mouthpiece if your wattage is turned up really high, but vapor expands, spreading heat through a wider area, and absorbs water readily, which also cools it down. vapor is actually cooler than your body temperature once it's out of the mouthpiece, it feels noticeably cold in the air",
"Are you all insane idiots high on monkey farts? Water is steam at 212f, of course it will burn you and your lungs. Vape isn’t steam from water. It is from vape juice which is made from propylene glycol or glycerin that has a fogging effect at a much lower temperature that can maintain suspension at ambient temps and humidity.",
"I don't know what these other people are talking about, but the reason it doesn't burn you is because it's mixed with room temp air. The majority of whats coming out of the mouth piece is just air that's drawn through while you take a puff. When they mix on the way through the temp evens out between the two. Think of the air flow in the device like a radiator on a car."
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c1jls2 | How can apple trademark "apple" | Technology | explainlikeimfive | {
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"The primary requirement for trademarks is that they be distinctive - they need to uniquely identify the product. Apple is the textbook example often used for \"arbitrary\" marks, the strongest category of mark. Apple makes computers. The word \"apple\" has nothing to do with computers. Therefore, there is no possibility that anybody else would need to describe a computer as an \"apple\", so the mark is extremely distinctive. The more plausible it is that somebody would need to use your brand name in describing your product, the weaker your trademark is. The categories are: 1. **Arbitrary**: The word has no relation to the product. Amazon has no relation to a shopping website. 2. **Fanciful**: The word is made up. Kodak film 3. **Suggestive**: The word relates to the qualities of the product. Greyhound bus lines - A fast animal suggests a fast bus line. 4. **Descriptive**: The word directly describes the product. Cold Ice Cream. These are generally not trademarkable, but long-term unchallenged use can make it more distinctive. Names are generally in this category too. Trademarks acquire or lose distinctiveness based on how closely consumers identify the product with the brand. McDonalds is a descriptive trademark, but it is extremely strong because of the prevalence of their brand in the public eye. Kleenex is a fanciful mark, but fairly weak because consumers habitually use their brand to refer to other company's products. Trademarks can overlap it it's not likely to cause confusion; Smith Auto Body in Des Moines is not likely to get confused with Smith Auto Body in Anchorage. Nor is Smith Auto Body likely to get confused with Smith Ice Cream, even if they're in the same town. Some trademarks are considered so distinctive that the existence of any other meaning, even ones that don't overlap would still weaken the trademark and are thus disallowed - Coke and McDonalds are examples. If you're named McDonald, you can't name your business after yourself. The Mc(thing) branding is so strong that you generally can't even use Mc(thing McDonalds doesn't sell).",
"Trademarks only apply within a specific industry or product type. They can trademark \"apple\" as a name for computer equipment because no one else was using it for that. They can't control its use for fruit, flavors or other unrelated stuff."
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c1jx1v | How are LEDs brighter and more powerful, yet use so little energy? | Ex: Police Lightbars, they're so bright but use so little of the cars battery. Much less than the classic rotating lights. | Technology | explainlikeimfive | {
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"You know a lot of light is invisible, right? Infrared, for example. You can't see it, but you can feel it on your skin with your eyes closed when you're standing near something really hot. Take two lightbulbs that consume exactly the same amount of electric energy, but one produces only visible light, and the other products half visible light and half invisible. The second one will look much dimmer. The old-timey incandescent filament lightbulbs, the ones that burn your fingers to the touch, they produce mostly infrareds! To the tune of 90%! That's why so much progress has been done. Because there was so much room for progress. LED lights produce mostly visible light. Do this is it. There won't be much progress anymore. We're there. We can focus on other things now. Cool, hey?",
"Old style lights work by heating up a something so it glows, giving off light. But glowing things will always give off most of their light as infra red, or, if you make it really, really hot, ultra-violet. Visible light makes up a small part of the spectrum of lights, so you can't make these type of lights efficient. Efficient lights, like fluorescent, sodium or mercury vapour, metal halide, high intensity discharge or LED, use methods other than just 'something really hot', to create only light that is in the visible spectrum. When you look at it this way, even these light sources are not really that efficient - turning less than 50% of the energy they use into light. But this handily beats 'hot thing' lights which are 5 to 10% efficient."
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c1kbuo | How can I use the touchscreen of my phone even after putting on a screen guard or a protective mirror on meaning I’m not directly touching the touch screen? | Edit: Protective glass, not mirror. | Technology | explainlikeimfive | {
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"There are 2 types of touch screens, 1 of them works by touch, the other one is more complicated one. Phones use the more complicated solution, as this allows you to use a nice looking glass screen. Multiple times a second, your phone sends an electric signal on an layer behind the screen, starting in an corner, and then detects it at the other corners.\\* Since electricity is predictable, the signal always comes in at the same voltage and time. This changes when you hold your finger near the the touchscreen, because your finger will alter the electric field, and change the voltages received at the other ends of the screen, then the device applies a smart calculation to see where you touched the screen. & #x200B; \\* In most phones, the way this gets done is even more complicated, as most phones support multi touch, see [ URL_0 ]( URL_1 )"
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c1lm7i | I have just heard of the concept of “splitters” for computers and have questions.... | 1. What are they? 2. This can be used for the computer and not just monitor right? 3. If my sick sister and I were in the same house with one monitor in one room and one different monitor in her bedroom, could we both “plug in” to the same screen to play various “one player games” each of us being played one? 4. If so, How can we do this and where can we get the materials? What’s the cost? Thank you! | Technology | explainlikeimfive | {
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"text": [
"[A screen sharing program like VNC would work if you have a spare PC to act as a remote viewing machine, and a decent WiFi network]( URL_6 ) As u/arlondiluthel mentioned, using two mice and keyboards at the same time can have weird effects, but it's mostly fine (we use dual control at my work all the time) and it's basically just the same as two people fighting on one mouse/keyboard. Only one mouse cursor will be visible, but it will jitter around if simultaneous movements of both mice are being made. To get stuff connected between rooms (instead of a screen sharing program) you can go oldschool and run cables to extend all the hardware from room to room. Benefits include less lag, and better screen update speed (smoother moving images compared to a screen sharing program which can be kind of choppy). All these links are to items on Australian eBay, but you'll be able to find local equivalents very easily.[This will extend a monitor signal to another room]( URL_5 ) [This will extend a mouse or keyboard (you'll need two pairs to do both)]( URL_1 ) [This is the type of cable to use with these devices, you'll need three in total (mouse, keyboard, screen), of whatever length is needed]( URL_3 ) If getting sound from the PC to the other room is needed too, there are a few options, cheapest being [20m 3.5mm audio cable extensions, a few chained together if necessary]( URL_4 ) and a [Y-split]( URL_0 ) Plug the Y-split into the audio output of the PC, run one side of the split to the speakers near the PC, and the other side goes to the extension to the other room and into another set of speakers. It's not a pretty way of doing it, some noise will probably get picked up and my audio engineer senses are cringing but it will work just fine:) [An HDMI audio extractor might be needed depending on how your PC's audio is configured.]( URL_2 ) Let us know if you want some clarification on any of this stuff👍",
"OK... so it seems like you're kind of talking about two different things. There's a device that's referred to as a KVM switch. This allows you to use one keyboard, mouse, and display for multiple computers, the switch typically has either buttons on it, or a specialized keyboard input sequence, to switch between computers. I have one that uses a remote to switch between computers. You can get one of these for as cheap as $20. If you're trying to do \"two users on one device\", you can connect multiple displays and keyboards/mice to a single computer, but then you will likely run into issues of input conflict. I don't know if there's software out there that can deconflict multiple inputs like that."
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c1t6tc | How does the flash in cameras damage paintings in museums? | Technology | explainlikeimfive | {
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"text": [
"Flashes used to emit a lot of UV which damages dyes and paint. Flashes no longer emit UV so they don’t do any damage. Museums have kept this rule for two reasons: 1. Flashes are really annoying for everyone else. 2. They have a higher chance of selling their book to you if you can’t take good photos yourself.",
"Light breaks down colors. The other day I found a green shirt I've had in my back seat for a few months and noticed that the part that caught light shining through the windows was really faded compared to the rest of it. Of course it takes a while to fade a color with light but the idea is that we try making the painting last for as long as possible and if there's hundreds of people flashing light on a painting every day, it'll severely cut the painting's life expectancy."
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c1uvaj | How does a computer shows the correct time even after we shut it down and pull out the power cord? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Most computers update through the internet once they are turned on. The motherboards also contain a small battery that maintains an internal clock, even when unplugged.",
"There's a battery, the CMOS battery, that keeps the internal clock running and manages the BIOS settings. When the battery dies the settings and clock get reset."
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c1yr3m | How does the nuclear material get put into a nuclear reactor? | That's probably a very poor wording of the question, but after having watched the HBO series Chernobyl I was left with the question of how the nuclear fission material actually gets surrounded by graphite and such that it can be used to create energy. The explanation the show gives states that machines and microchips break down due to the gamma radiation, and their is too much radioactivity for that to be someone's day job. My question is really how 1) is the material mined, and 2) how does the material get put into the graphite/whatever compound is used, or how did it (as times have changed and so has technology)? If there is a link you could provide that might be helpful, by all means, but not being a nuclear engineer I can promise you I probably won't understand it. | Technology | explainlikeimfive | {
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"text": [
"In this case, uranium isn't that radioactive. First of all, its not highly enriched uranium. So most of it is the less radioactive kind. Secondly, even the more radioactive uranium isn't that radioactive. The fuel rods are safe to handle with some protective equipment. As for mining, uranium ore isn't that much more radioactive than regular dirt. Or even a Banana. Uranium becomes very radioactive by artificially bombarding them with neutrons, causing chain reactions where uranium being bombarded will bombard nearby uranium with its own neutrons."
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c1z73d | What makes a computer programmable and not a single purpose machine? | Technology | explainlikeimfive | {
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"text": [
"It's whole structure. The CPU is just a blank calculation machine. It gets data and commands from the memory and writes data back into the memory, so what it does depends fully on what is saved in there. An analogy would be a toolbox, you have different tools, for different tasks, but the order and how you use them can be freely chosen. I hope this answers what you were asking because I don't fully understand your question"
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c1zg8l | what happens if i play a 1080p video on a 720p display? | Technology | explainlikeimfive | {
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"text": [
"The image gets shrunk. There are several ways of doing that. You could just skip pixels. So for instance, a line from the image with 8 pixels: 12345678 when shrunk by half would become: 1357 You don't need to do it by halves, for instance you could do by a third by removing every third pixel: 124578 But that doesn't give the best results, because it looks really bad on fine details. Like if there's a single pixel thick line somewhere it can just vanish entirely when you do things that way. So a better way to do that is to average the pixels. If you have a black line surrounded by white and shrink that you get a middle grey sort of line."
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c214x1 | Does restarting a computer actually do anything or is it just a placebo? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Restarting the computer forces everything in the computer to shut down and start again so any processes that were giving you trouble could just fix themselves like that",
"Just a related note,unplugging and plugging something back in again is an actual repair step as well. Besides pulling all power from a device it corrects a condition known as terminal fretting common to connectors and plugs. Unplugging and plugging back in creates new contact points between the terminals or pins in a connector. Actually a really common issue in vehicles and basic electrical classes teach you to always use dielectric grease in every connector which helps combat the condition."
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c2321j | How does compressing and decompressing a file with GBs of space work. | Technology | explainlikeimfive | {
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"text": [
"File compression works by representing big repeating patterns with little ones. The classic example would be \"aaaaabb\", which you could condense down to \"5a2b\" or \"5abb\" since changing the b's doesn't save size, so why bother? Streaming compression algorithms work this way. This is in contrast to block compression, where we would make a table, \"1 = aaaaa, 2 = bb\", and then our data would be \"12\". You need the table and the data to decompress. & #x200B; Then we get real clever. What if you arranged your data in a 2D grid, rows and columns, and then you rotated the rows and columns like a Rubix cube? You could arrange your data to make bigger patterns - if you had a bunch of a' all over your data, you could line them all up, and that would be one entry in your table. You could compress the table, too, so instead it would look like, \"1 = 5a, 2 = bb\". So if you had GB worth of just a's, you could reduce it to a count, a symbol, an entry into a table, and then a list of steps you used to reorganize the original content, so you could play it in reverse and get it back. & #x200B; That's lossless compression. Lossy compression intentionally throws away information. Less information, less to compress. What was lost can be deduced and reconstituted from the remaining information, though it's an approximation. This compression is best suited to audio and video, because the approximation is indistinguishable from the original by any way you measure it with your eyes, ears, or through computation."
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c23ol6 | what exactly is happening when a volume dial breaks and starts turning the volume up instead of down or vice versa? | Technology | explainlikeimfive | {
"a_id": [
"erisdak"
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"text": [
"Do you mean a rotating volume dial, like found on an AV reciever/amplifier? They are rotary encoders. They're supposed to repeatedly count +1 or - 1 when you turn up or down. When they get dirty, they can count all sorts of things instead. Here's [a video]( URL_0 ) of a guy dismantling and cleaning such a dial, to fix an erratic volume control"
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c25afd | How are "mesh" WiFi setups different than a single router with WiFi extenders? | Doesn't it all come back and get congested at the same point? I understand that with a true mesh, the "sub-routers" or whatever can talk to each other but I don't see how that doesn't still result in weaker connection away from the main router and overall congestion at the main router. | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"WiFi range extenders are basically just wireless routers without the 'Router part' (AKA: Wireless Access Points). They plug in to your router using a wired connection and create a separate wireless network. If it connects to your main WiFi wirelessly, then it becomes a Wireless repeater, which doesn't work as efficiently. - With range extenders, your device (Phone, laptop, etc.) must determine which access point to connect to, this usually isn't very reliable as most devices will want to stay connected to their current AP for as long as possible. & #x200B; WiFi Mesh systems more closely resemble enterprise WiFi systems, in which a single device controls all of the wireless access points and it creates one single network. This controller will monitor all of the wirelessly connected devices (IE: Your phone, or laptop) and determine which access point they should connect to. This means you can walk around your house and your device will seamlessly connect between multiple access points to maintain the strongest possible signal. Some WiFi mesh systems will connect their access points through wireless signals, but these will still be vulnerable to interference just like range extenders. The best way is to connect them using wires. & #x200B; **TLDR:** WiFi mesh works better because the router will control which access point your device connects to in order to maintain the strongest possible signal. Both mesh and range extenders suffer from interference if you connect them using wireless instead of wires."
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c264gl | how does one do a reverse image search, and how does this technology work? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Let’s look at drinks. For each drink, we’ll keep a running total of ‘points.’ If it’s hot, it gets one point. If it’s cold, it loses a point. - Coffee is hot, +1 - Tea is hot, +1 - Milk is cold, -1 So we can see coffee and tea are more similar to one another than to milk, using this system, right? We could make a similar system vastly more complicated, using hundreds of properties so that only a computer could check them all - color, shade, shape, texture, etc, anything you can name that makes an image unique and recognizable - to relate images to one another. You upload your image, the computer checks the image, gets the score, and then cross references that with the scores of other images - and it shows you those images under the assumption that they are similar.",
"Basically, the image is fed into a program that looks at the image and creates a mathematical model (sometimes called a fingerprint or hash) of the picture (how this is done is way, way beyond ELI5). The model is then compared to other models that exist from previous images that have gone through the same process. If the models are similar enough (say, 90% the same) then the reverse image searcher will display the compared images."
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c271g7 | How can people on the phone not hear themselves when on speaker? | For example, my car speakers are very loud and i can hear people very clearly, how does none of this sound get transmitted back to them? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Speaking as someone who answers phones for a living, I do hear it. It’s awful when people call me on speakerphone/from their car.",
"As the phone broadcasts your voice, it add a inverse sound wave of your voice to the recording of the person you are calling to cancel your voice out. Like noise cancellation technology.",
"The sound that is being sent out to the speakers is also copied, phase inverted, and fed into the microphone circuit. This cancels out a lot of the speaker sound the microphone itself picks up. Not all of it, though. Some phones have additional circuitry in this system to monitor for echo and to adjust phase and delay of the feedback signal to minimize echo."
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c27zfq | How does animation work? I thought they drew every single frame up until a month ago. I know that 3D animation is done on a computer with models and what not but the whole concept of animation still blows my mind. | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Historically, animation has been drawn one frame at a time. The primary artists might draw out key frames then hand them off to a group of animators who draw the frames in between. These days, you can have a computer interpolate the from and to and generate the frames in between. With 3D animation, you can do it in the same manner with the animator positioning the meshes of moving things for each frame. But it's sometimes more practical to use cameras to follow a real actor making the movements which are then mapped on to the 3D mesh to make it move.",
"If you have half an hour free, you can watch a [tutorial]( URL_0 ) on 3D animation.",
"Animation works like any other video: it's a series of images presented at at least 24 images per second, so that the images appear to us to be one continuous movement. & #x200B; Traditional animation involves hand drawing every frame, but is rare in the modern day. Modern animation on computers (even 2d animation) uses software tools to let you draw the character once, then you tell the computer how you want to move. The software then uses that to generate the individual frames and export it as a video."
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c28max | How is data conveyed over waves such as WiFi? | How can a wavelength possibly carry enough information to load say, a video? How can one wave carry instructions for hundreds of thousands of pixels? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"> one wave One wave *frequency* travelling at the speed of light. By changing either the frequency or the amplitude of waves, you can convey ideas like \"on\" and \"off\". For example: you can program an antenna to understand that a wave peak above X volts is a 1, and below X volts is a 0, over a given period of time (typically miniscule fractions of a second). Because light is fast [source required], you can communicate a LOT of 1s and 0s over a short period of time. Those 1s and 0s are translated and compiled as code which executes as whatever data the application is trying to run, like a movie. Edited to fix mobile autocorrect"
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c29iwl | How does lane assist in cars work? | Technology | explainlikeimfive | {
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"text": [
"The car has a camera that points towards the front of the car (at the road). It scans for the markings on the road that show where the lane is, and then if it notices that the car is shifting to an angle where the markings don't line up, it does its thing (makes a sound or pushes back on the steering wheel - different systems have different functions). It won't work well on roads that don't have markings or where the markings are worn down, or in some types of weather."
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c29s6h | Why do monitors display more things on the screen while they have the same resolution as laptop screens? | For example: a laptop screen may show 8 icons on the desktop but when connected to a monitor bigger in size (inches) it may show 10 icons on the desktop even though both have same resolution so things should just look bigger | Technology | explainlikeimfive | {
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"text": [
"Laptop screen resolutions can indeed show as much content as desktops, but they are physically smaller. Condensing to that scale would work, but everyone would be squinting at their laptops.",
"Windows 10 has separate display scaling for each screen. If both screens are the same resolution, but one fits more icons than the other, then it is probably becsue they have different display scaling set. [Link to display scaling article]( URL_0 )"
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c2b7so | How does the "harvesting" if renewable energy work? How do windmills get power from spinning? How do solar panels make energy from the sun? How does the conversion of the energy from one to another work? | Technology | explainlikeimfive | {
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"eriytm9"
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"This is all ELI5 levels of course. I don't know enough detail to ELI10 Windmills are blown by wind - the wind collides with the blades and causes them to turn. The windmill is linked to a big-ass magnet, and that big-ass magnet is inside a big-ass coil of wire. When the big-ass magnet rotates, it energises electrons within the wires, creating electricity. In solar panels, photons from sunlight bash into electrons within the solar panel. This gives them energy and causes them to become free from their host atoms. They run into metal 'collection' plates, and then into wires from there."
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c2bi0j | When your phone is ringing, why are the electronics around it buzzing? | Technology | explainlikeimfive | {
"a_id": [
"erj1jpf"
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"text": [
"I don't think that's what OP is asking. You can have a phone on silent, sitting next to other electronic devices, and you'll often hear very distinct electronic buzzing type noises from the other devices specifically when the cell phone is ringing."
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c2bydd | Why it's not recommended to cool down a heated up smartphone in a fridge? Isn't this the same as taking out your working smartphone in a winter (from warm room to cold street)? | Technology | explainlikeimfive | {
"a_id": [
"erjb58n"
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"text": [
"Kinda, And ive seen companies say \"Yeah, our phones werent designed for this. Now you got water damage. And water damage isnt covered under warranty, so pay up!\""
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c2ige6 | - How can it be, that we went from Roman times up until the late 1800's with the horse and chariot/carriage. And then in less that 100 years managed to reach the moon. | Technology | explainlikeimfive | {
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"Technology scales exponentially. Better technology begets better technology and has forever in all fields. We spend hundreds of thousands of years as nomad hunter gathers before we invented agriculture, then really quickly we developed cities. Basically the better technology you have the better technology you can make, its a positive feedback loop of progress:",
"Your comparison makes it sound as if there was no technological advancement in all that time up to the 1800s. There was, it just accelerates over time as technology progresses somewhat exponentially since one achievement allows for multiple more that built upon the first one. One big factor that compounds this simply is human population growth: In Roman times there were maybe 200 million people, around 1500 half a billion, around 1800 one billion, by the 1930s over two and by the time we flew to the moon in the '60s it was over three billion - more people means more specialization and invention and discovery.",
"Simply put. We use technology to create newer and better technology. So the better our technology gets, the better technology we can create with it.",
"This also misses coal, steam, electricity,and flight overall. There was a lot of innovation, it just wasn't necessarily available, where the horse and buggy are pretty easy to get your hands on. ++positive feedback loop. Technology is compounding and its change is exponential. We went from no internet, to entirely running some of the biggest companies in the world on it with no local server/rackspace. The barrier to entry continues to be lowered.. Eg tesla roadster was $130,000 as an early electric car. The model 3 is $35,000.",
"/u/Petwins (and others) already noted the exponential growth of technology, which is the ultimate answer to your question, This is a long read (and this author has written book-length explorations based on this topic), but I strongly recommend Ray Kurzweil's *The Law of Accelerating Returns* ([ URL_0 ]( URL_0 ]( URL_0 ))) to people interested in futurism or technological growth generally. You note that it was 100 years from the horse and carriage to the moon, but what's even more insane was how *primitive* some of the computers used in the moon mission were. We haven't slowed down since then. We've actually sped up in many fields, particularly ones based on information rather than consumption of raw natural resources. (If our rocket power had grown since 1969 at the same rate as our computing power, manned flights to Mars could be relatively routine.) The exponential growth of technology is a major reason why sequencing the human genome took many fewer years than predicted, for example.",
"There is multiple factors. But maybe one quite important recently was scientific revolution. Someone figured out that you cannot figure out how the world works only by thinking logically. There may be many explanations to some phenomena that are all logically valid. How to find out which of these explanations is actually true? The answer is by experiment. You can do an experiment, that tests a theory, and it can either verify that the theory was correct or it may reveal a problem in the theory. And the nature is always right, so the theory will be improved. Then there is a new theory and it is tested again by experiment. Precise details about how the experiment was done, are documented and shared with other scientists. This way other scientists can repeat the same experiments and check if the theory holds up or not. So this is a systematic process for finding out how the world really does work, and a process that reduces human error. In science, authority, etc. don't have value. There must be proof for the theory, and the theory must be so that others can verify it by themselves. This process of finding out information proved to be quite effective and so as a result a massive amount of new discoveries was done very quickly in only a few hundred years. People started to utilize this information from circa 1600-century onwards, and already at early 1700 century, first steam engines were built. Indeed this process has a positive feedback loop as well. There is also other factors involved, like the development of the society. For example education, especially education of engineers in the case of technological development has stimulated development very heavily, like in Germany at the late 1800 century, availability of educated engineers stimulated the technological development heavily. Also bigger scale events have had their effect like wars. War or some other similar thing, that puts countries to invest massive amount of resources for developing something new, have also stimulated the development. There is a lot of people around the world with crazy ideas. But to find financing for those crazy ideas, exceptional times are often needed, like for example a war or race to the space, etc. Both USA and Soviet space programs were based on the German rocket developments and those got financing because of WW2. But would same idea have gotten far in \"normal\" circumstances? Probably eventually yes, but at a much slower pace."
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c2jnmd | - How does a single 3.5 mm jack provide stereo sound? | So on my way back home I was listening to music on my bike and I got fascinated by a sound panning from left to right in my earphones. (I was listening Ready or Not by the Fugees). How does a single contact like a 3.5 mm jack provide a stereo sounding effect? How is it able to split the sound between both earphones? | Technology | explainlikeimfive | {
"a_id": [
"erkibl3",
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"text": [
"You will notice black bands on the jack. Stereo will have 2 bands, making 3 connections; L, R, and common. Some new headphones with buttons will have extra bands.",
"A 3.5 mm jack isn't a single contact; it's three. A standard headphone jack can therefore carry three signals. In most that's left ear, right ear, and ground. You can get 3.5mm jacks with more contacts too, some have 4 or even 5 and so can carry microphone or video data as well as stereo audio."
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c2lpxy | How can some companies offer unlimited cloud storage for an affordable monthly subscription while others charge an arm and a leg? | For example, Drop Box allegedly has an unlimited storage plan for just $20 a month, but Google drive offers like 20TB max for $200. Why is there such a difference in pricing? Is it even possible for companies to offer “unlimited storage”? Does the computing power for unlimited actually exist or are they saying “unlimited” while believing they’ll never need to worry about it? | Technology | explainlikeimfive | {
"a_id": [
"erkyxej"
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"text": [
"First off, that 'unlimited' remark us correct, they're just saying that assuming you'll never actually be a problem. All data stored on the cloud is actually kept on hard drives in servers somewhere. Some companies have their own, but a lot just rent server space from other companies that make giant server farms for this purpose. Amazon runs one of the largest server farms companies out there, called AWS. They can say unlimited because while your computer might have 1tb of storage and your phone might have several hundred gb, their servers will have billions. It'd be like if I had a warehouse the size of ten football fields and rented 'unlimited' storage space to you. Realistically no one person is going to have enough stuff to fill the warehouse, even if you had several houses worth of furniture you needed to store, so it might as well be unlimited. Kind of like how buffets serve 'unlimited' food. It's not really infinite food, just more than one person could possibly eat. You might say that while one person could never fill that warehouse, a single company could, or that enough people could eat all the food at a buffet, which is true. If you look at those cloud providers, they probably offer personal use options and enterprise options, because they know businesses or large organizations will have a lot more storage needs. If they ever start to run out of space, they can always rent or buy more servers. There's also differences in services offered. A cheap cloud solution might have a single site with comparatively low speeds, while a more expensive one might have your data backed up to several sites all around the country so even if an entire facility burns down your data is good. They might also have better upload/download speeds and security features, Alon with other stuff to justify the price. A storage place that's just got a roll up door with a pad lock is going to be cheaper than one that's got cameras, climate control, guards at a gate, a forklift on site that can load and unload stuff for you, and other benefits."
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c2n5dv | - How do those labour simulators work, and are they safe? | Technology | explainlikeimfive | {
"a_id": [
"erm387b"
],
"text": [
"So a labor simulator uses electric pads that are placed over specific abdominal muscles. When activated, they send an electric signal to the muscle causing the muscle to contract in much the same way that your brain sends an electric signal to your muscles. To simulate labor, the machine causes the muscles to react in the same way that they would during a contraction. They are safe, though they would make you sore for a few days after. I wouldn't reccomend it because first, contractions fucking hurt (can't move, can't breathe kind of hurt) and second, they aren't a fully realistic representation of labor anyways."
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c2t0b6 | How does a weighing machine work? | Edit: I'm talking about a weighing scale. | Technology | explainlikeimfive | {
"a_id": [
"ermd7d5",
"ermd91v"
],
"text": [
"In general scales use springs with a known spring coefficient. This means that the designer knows how much force is required to extend a spring a certain distance. This distance can then simply be translated to a weight. Digital and electronical scales usually use something called a \"strain gauge\". In general this is a material, say a piece of iron which when a force is applied to will deform. This deformation will affect its resistance and by running a current through and measuring the voltage or the current one can calculate what force has been applied which corresponds to a weight. Edit: spelling.",
"Electronic scales use load cells, these are devices that measure force via resistance change due to contraction of the cross section of many small conductor bands. They are than calibrated with standard forces, and the display shows you the mass in kg or lbs by assuming g=9.81m/s^2, i.e. assuming you are a non moving object in earth."
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c2vc1g | How do filmmakers/artists make a bright/blinding white compared to a normal white? | Technology | explainlikeimfive | {
"a_id": [
"ermrm3c"
],
"text": [
"Contrast. If a scene is largely dark, a bright spot will appear brighter than if that brightness were to fill the whole screen. Likewise if a scene is dark and then cuts to a completely white screen, our eyes will have to adjust to the change in brightness, and it will appear brighter than it actually is."
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c2vma8 | How do metal detectors only sense metal? | I've always wondered how they are able to pick metals up on the scanner and not other materials | Technology | explainlikeimfive | {
"a_id": [
"ermso5n",
"ermsrye"
],
"text": [
"They're looking for materials that interact with a magnetic field. Out in nature, this is almost always a conductive metal. There are other materials that react to or interfere with the magnetic field and could produce a false reading, but they're pretty rare. You're unlikely to stumble across a deposit of magnetic ore or some kind of human-made conductive ceramic while checking the beach for jewelry.",
"Ferro metals! It's using magnetism. That's why you have these disk shaped, and even hollow circles. Current flows through there, creates a magnetic field. If any ferro-metal is in the ground it disrupts the magnetic field and the operator gets a signal"
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c2wve3 | If real-time satellite imagery technology already exists, why are surveillance drones used in hostile areas? | Edit: I got a very helpful and detailed explanation from u/SeanUhTron, quoting his comment here for other curious people to read: > Geosynchronous satellites do exist, but they have much higher orbits, putting them further away and making data transmissions slower and photos less clear. > > Drones are used because they can get much more data such as radio transmissions, clear photos, and they can be easily replaced if lost. Satellites are very vulnerable to ASAT weapons and take a long time and a lot of money to replace. Satellites also only fly over their target areas during certain times of the day. If the enemy knows this, they can plan ahead and only move troops and equipment during the times they aren't visible to satellites. [Here's a link to that reply]( URL_0 ). Thanks! Edit 2: u/brainwired1 also has provided several reasons for using drones instead of satellites, notably the occasional presence of clouds and smog, as well as the fact that satellites are more costly. Thank you as well! | Technology | explainlikeimfive | {
"a_id": [
"ern14ut",
"ern1yd2"
],
"text": [
"Real time doesn't mean they can see every area of the globe simultaneously. They still need a satellite overhead, and they typically move. A drone can be sent to a specific area and linger for hours.",
"Satellites are moving several thousand miles per hour, and they cannot slow down or stop. You can get real-time satellite imagery, but not on-demand, and only for short periods of time. If you need some quick pictures, you use satellites. If you need video surveillance over a long period of time, you need drones."
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c3051a | What are those tiny little numbers on the bezel of my wristwatch and why do some of them rotate? | Technology | explainlikeimfive | {
"a_id": [
"ernqlf8"
],
"text": [
"That depends on the type of watch that you have. If the numbers go from 0 to 60 (and usually those are the spinning type), it is intended for keeping track of time since you started something. They’re called dive watches, used by divers to keep track of how long they’ve been underwater. You spin the arrow to the minute hand of when you started, and when you look you can easily read the difference without remembering any numbers. Other types have a tachometer. These go from 60 to anywhere from 240-500. If you are racing a car (or any other vehicle) you start your timer and stop it one mile later. The second hand will point at your average speed in miles per hour (also works for kilometers and kilometers per hour) There are probably other niche watches with different numbers, but these are by far the two most common ones."
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c32y29 | ELI: in coding, how is a randomizer itself actually coded? | Technology | explainlikeimfive | {
"a_id": [
"eroayms"
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"text": [
"Yes this is a big problem. Since nearly everything in a computer is essentially a function, and multiple functions put in sequence or parallel are still functions, then mathematically the concept of random doesn't really exist, you cannot have a function whose known input produces a \"random\" output. There are a few ways around this. There are a number of functions that help generate random data from random data known as a \"seed,\" known as pseudo random number generators but at some point along the line we need to initially feed it some random data to get more random data. And these functions aren't ideal either. So anyways there are mainly two solutions. 1. Ask the operating system. Most operating systems tend to have some scheme of producing random data. They often collect mouse clicks, keyboard strokes, some files, and toss all of that into one of those pseudo random number generator functions. If you have a mac or a linux device, generally speaking the operating system's random data cache is in a \"file\" /dev/random or /dev/urandom depending on your use case. This still isn't ideal as we use nonrandom input to generate random input but the idea is that there is that there is just a lot of data that no attacker will be able to get, like keyboard strokes and their exact timings, and that in theory secures this from attackers. 2. Hardware random number generators. Most modern CPUs come with a section of chip responsible for generating random data. This chip is often known as a ring oscillator, basically as it turns out if you have an odd number of NOT gates chained together in a ring, wacky stuff happens and the electricity in this device spazes out, with spazzing changing depending on environmental factors such as temperature. For instance, most recent desktop computer CPUs come with the command RDRAND which can be executed to produce random data. This is also added to the random input pool of the software RNG from 1, which adds security to its randomness."
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