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7hwe6p | how does the 3DS's 3D work? | Technology | explainlikeimfive | {
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"Your brain sees 3D normally by combining the separate pictures it gets from each of your eyes. The basic idea behind 3D graphics is to display two different images, one in each eye. If you make the two images slightly different, then the brain interprets them in the same way as your normal sight, and makes them look 3D. With 3D movies, this is done by displaying two pictures interlaced with each other so that every alternate line on the screen is a different picture and using polarised light. When you put on the glasses, the polarised lenses cancel out one of the images in one eye, so your brain gets two different pictures and makes them 3D. With the 3DS, the two images are displayed in interlaced vertical lines, and then to make sure that each eye sees a different picture, the 3DS has tiny walls that block your left eye seeing the right eye's pictures and vice versa. This diagram shows how that works: URL_0 As you move the 3D slider, the images separate or overlap more, and the walls become opaque or transparent."
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7hwizm | how does "mind uploading" qualify as a valid form of life extension? Wouldn't it simply be a digital copy of yourself, and not a continuation of your original existence? | Technology | explainlikeimfive | {
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"Any form of “life extension” that breaks continuity of self is a complicated subject, as the extension only applies to the new continuity and is broken for the old one. It’s a matter of personal opinion. Going to sleep and waking up does not break continuity of self, nor does general anaesthetic. However, if you made a perfect copy of yourself and then killed your original self, continuity would be broken. The 2015 video game SOMA is a fun game that focuses on this subject, too."
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7hwyla | How does a computer unset a bit (set it from 1 to 0) in memory/storage? | Technology | explainlikeimfive | {
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"It depends on the particular kind of storage. In magnetic storage, like a spinning-disk hard drive, it magnetizes the region storing the bit in the opposite direction. (In practice, hard drives write entire blocks at a time, but the technology could theoretically be managed a bit at a time.) In typical flash storage, like in solid-state drives or external flash drives, it can't write a single bit at a time. In order to change a bit from a 1 to a 0, it erases an entire block of memory, then rewrites the new data into it. In DRAM, which is the typical kind of RAM in a computer, it connects the capacitor holding the bit to a current drain, which allows it to discharge. (Similarly to others, standard DRAM actually can only write a whole line at a time, so switching a single bit means writing the previous value into all the other bits.) In SRAM, which is typically used for things like on-CPU caches, the bit line is set to 0 and then the write line is set to 1. The transistors switch into the alternative configuration, and then the write line is set back to 0, which causes them to maintain their current configuration until written again.",
"Depends on the method of storage. Hard drives are known as magnetic memory. They consist of large plates that have tiny tiny sections which can be individually magnetized by something called the \"drive head.\" It is magnetized similarly to how a nail is magnetized when you rub a magnet against it, though this process may also demagnetize it if done correctly. Reading it is simple, as the drive head flies over the magnetic section, the moving magnet generates an electric current in the drive head, which is transmitted to the computer itself. If magnetic then 1, if not then 0. RAM is a different story. Hard drives are slow so RAM exists as a fast cache that is used because the CPU needs fast memory to do its thing. So RAM exists for this purpose. At its simplest, it uses capacitors. These are kinda like rechargeable batteries with a few main differences, they are fast, can't hold much, and can't hold for long. Here, it is pretty simple to do. Charge in capacitor = 1, no charge = 0. The interesting thing is the convoluted setup this requires. Capacitors must be discharged to be read, so reading requires discharging it then reloading the capacitor. Capacitors also can't hold charge for more than a few milliseconds at best when disconnected from a power source, so every few nanoseconds, the machinery reads the bit and recharges the capacitor if it is a 1. Lastly is flash storage, something that uses something called a floating gate transistor. A transistor is an electronic switch in most cases, it isn't meant to be as a form of storage of charge, but we found some witchcraft that no one knows how works where we can store electric charge in a transistor for mostly indefinite time. This too requires discharging to read but once again a similar strategy is used here. This is used in SSDs, flash drives, and other \"flash storage.\""
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7hyawq | How does "8-dimensional" music work? | There are numerous so-called "8-dimensional" music tracks or sound sequences to be listened to with regular headphones, like [this here]( URL_0 ) (music) or [this]( URL_1 ) (barber shop). Despite ones musical taste, I find these impressive - but they are made for 2 speakers, and Stereo is a quite ancient technology we had for a long time, so how does this effect work? | Technology | explainlikeimfive | {
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"It has to do with the ways our brains interpret position and distance of sounds based on the sounds each ear receives. There are two main important aspects: First the shape of your ear and ear canal actually subtly modifies the frequencies of the sound that enters it, depending on which direction the sound has entered from. The frequency profile of the sound that reaches your eardrum will be slightly different if the sound enters from behind vs from front. It'll be even more different if it comes from the other side, as some of the vibrations have to go around your head or even through your head. Your brain is very sensitive to those subtle differences and can use them to determine the position of the sound in space. This is often called HRTF - head-related transfer function. Second important cue is the time difference of the same sound arriving to each of your ears. Because the sound waves travel at finite distance, sound arriving from the left will arrive to your ear a few milliseconds sooner than to your right for example. These subtle effects can be captured using special binaural microphones, that [look something like this]( URL_0 ). They essentially model human ear and ear canal, with a microphone where the eardrum is and have the ears positioned about the same distance apart as you would. That means that the captured audio has both these spatial cues already \"baked in\", so when it is played back, your brain thinks the sound is coming from a certain point in space, even though its source is right next to your ears, sort of like a perceptual audio illusion! The effects can also be simulated in software, essentially as a form of audio filter, so you can produce artificial sounds that seem to be coming from certain point in space. This is very useful for virtual reality applications for example. Hope this helps!"
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7hypwb | How does Whatsapp make money/profit? | Technology | explainlikeimfive | {
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"When a product is free, you are the product. Despite facebook telling us it's secure, I'm pretty sure they run a ton of analytics algorithms on your contact list, most used words, hours of sleep, ..."
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7hytt3 | Why do people still use i3 and a lot of i5 CPU when i7 is available? | Technology | explainlikeimfive | {
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"1. For most casual users and even a lot of gamers and such, hyperthreading (the main advantage of i7s) will make little to no difference. Beyond that, an i5 and i7 really aren't notably different performance-wise if you're comparing like clock speeds. Hyperthreading basically means that for any physical processor core, the processor essentially has two 'cores' the operating system can address. This doesn't mean it works twice as fast, it just means that if an application is hogging a core but not actually doing something at the moment, another application can utilize the core. As a result, you'll ONLY see any difference if you're significantly utilizing more than 4 cores. Generally speaking, casual users and gamers really won't, as the vast majority of applications (even games) only use one or at MOST two cores at a time. So at most, the operating system and any background tasks might use one core, your game might use at MOST two, and any other random stuff on your computer can use the fourth core on your i5. Adding 4 more virtual cores does nothing. You could add 4 more physical cores and see no difference. 2. An i5 will generally be ~$100 more than an i3. and an i7 will generally be $100 more than an i5. If you aren't oozing money out of your pores, that extra $100 if you don't need hyperthreading or $200 if you don't need a couple extra cores means you can put that money into something that will make a lot more difference for the task you'll be using your computer for, like a faster SSD or a better graphics card."
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7i1zuc | How does scaling to 1440p work?(upscaling/downscaling from 1080p/4K) | Technology | explainlikeimfive | {
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"If downscaling, you take every 4th pixel to get from 4k to 1080p. If upscaling you make up pixels to go between the existing pixels. This is done typically by averaging the nearby pixels. Obviously 1440 isn't a perfect fraction of 4k, so the math is a little more complicated, but the process is the same.",
"Interpolation via algorithm. The image is inlarged and the data from the images is use to calculate (guess) what color to make the filler pixels, since the device has to make up something to fill in the gaps."
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7i26fc | What is the difference between a decentralized trading platform and a centralized one in terms of crypto currency? | To me the only difference I can see is that one uses logins and 2FA and the other uses wallet addresses and private keys, but I think there must be more to it than that. | Technology | explainlikeimfive | {
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"Centralized: there is a \"main\" server (or group of servers) that keeps track of everyone's accounts. Transactions must be recorded there. Decentralized: transactions can occur anywhere, and no particular computer is the \"main\" one."
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7i3nx2 | Why did Google get in trouble for collecting open WIFI data? | Google Street Cars collected Wi-Fi data when they were driving around. The data they collected was from WIFI that was unprotected that anyone could grab. Since they didn't hack into anything (unless I misread it) and anyone could grab the same data why was it a problem? | Technology | explainlikeimfive | {
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"If I put 100$ in a box and put that box on my porch, if someone takes that box is it theft? the answer is absolutely yes. Just because it isn't secured doesn't mean its free to take."
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7i4m0x | How do laptop batteries have such low capacity yet can last several hours? | Many laptop batteries only have about 4000mah or so. That means even if they use only 1a of power they only last about 4 hours but most laptops can last much longer. I see this with smartphones as well. How?? | Technology | explainlikeimfive | {
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"Battery capacity is only one part of its important parameters. Equally important is its voltage. If you have 3 2000mAh LiIon cells and connect them in parallel, you get a battery pack that has 6000mAh capacity, with nominal voltage 3.7V (I think, but exact numbers aren't important for this explanation). But you can also connect them in series, so you achieve 11.1V (3*3.7V) voltage, but still only 2000mAh. Yet the energy of both battery packs is the same. If we (for sake of easier calculations) assume that the cells provide all of its power at 3.7V, then we get 6Ah * 3.7V = 22.2Wh ~= 80kJ of energy from the first pack, which is equal to 2Ah * 11.1V = 22.2Wh ~= 80kJ of energy from the second pack. So it's not \"fair\" to compare battery packs solely on their capacity, unless you know that they provide around the same voltage. For a more practical comparison between different battery packs, you should take their voltage into consideration, or compare their total stored energy (a figure usually presented in Wh units). I'm almost certain that most of laptops use higher voltage battery packs (than 3.7V, which is nominal LiIon voltage). There are many clues to this: * Most of notebook chargers provide 19-20V * USB ports provide 5V, although that is achievable by stepping up the voltage from 3.7V, it's much easier, more effective and cheaper design to use higher voltage source to power this 5V output * Lower voltage means higher current while getting the same power. That needs thicker conductors, higher voltage drops, more difficult and costly design... * And as you said, 4Ah * 3.7V is just below 15Wh and from memory, 15W is about max TDP of a mobile processor. That would mean that the notebook's processor could be running (at full throttle) for just 1 hour, assuming all the other components (including screen) are turned off and 100% efficiency. And this doesn't fit the observations.",
"Because thousands engineers have spent years of their lives reducing the amount of power consumed by laptop chips. This includes making them run on lower voltage, and making each transistor very small so it uses very little current to turn on or off."
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7i96d8 | How does a rubber ducky work? [USB hacking device] | Does it work like keylogger? Is that the only way to use it? | Technology | explainlikeimfive | {
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"It's not a keylogger, it's going the other direction. The computer reads it as if it were a keyboard sending button presses to it. It's designed to let you get into stuff you shouldn't. How does it do that? 1. computers almost always \"trust\" keyboards, even when other USB devices like thumb drives are blocked. Thus, this thing says it's a keyboard when it ain't. 2. It's possible to do pretty much ANYTHING on a computer if you know all the keyboard shortcuts to it. So the idea is you figure out the key combination to do something naughty (typically something like winkey-R to pop open the Run dialogue, then enter a long command), program that onto the Ducky, then stick it onto your halpless victim machine. It does in 2 seconds what would take you ten minutes. You could even put a whole malicious program on there by having it pop open Notepad, type up the code for your naughty bug, then save as and run the whole package."
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7iaejf | How come most games on PC only run through Windows only? Shouldn’t it be easy for games to run across all platforms? | Technology | explainlikeimfive | {
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"> shouldn't it be easy for games to run across all platforms? nope. Different operating systems have different default libraries and resources, and require the game to be developed more or less independently on both. Its like asking \"if i know how to drive in the U.S why cant i just drive in Britain the same way\".",
"Why should it be easy? Programs generally assume your system has core drivers and libraries that it needs. Most PC games need DirectX to be able to draw anything on the screen in a timely manner, only Windows comes with DirectX. No DirectX means they have to rewrite all of their graphics to use OpenGL or another library, its basically rebuilding the entire engine Making games work well on Windows using DirectX takes enough time and effort. Making them work with DirectX and OpenGL and whatever else may be out there will take even more, and since there isn't a huge demand for non-Windows based games there isn't a business reason to do it",
"Former game developer here, In the PC market, the principle problem is the game has to rely on operating system resources, and not all operating systems speak the same language, offer the same resources, or meet the same expectations. You have to account for these differences in order to first make a program build, let alone run, let alone run well. And historically, you had to contend with different hardware platforms - CPU architectures. This is less of an issue now, since Xbox and Playstation are both x86, as well as PCs and Macs, but that doesn't mean it's going to stay this way. There are also hardware resources that make these systems different as well - and again, you have to account for that, if anything to be performant. Once again, not all CPU architectures offer the same resources or expectations. When I got into game development, you could not expect handheld platforms, for example, to have CPU support for division! Or even floating point (decimal) numbers. This is also why emulators are extremely hard to get right - it's not simply mapping one architecture's opcode to another's."
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7iepd4 | Why does quickly looking up and down at a smartboard projector light create a very brief display of RGB light? | Technology | explainlikeimfive | {
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"It uses a technology called Digital Light Processing or DLP. The way it works, basically is that those projectors send out, in sequence, the red parts, green parts, and blue parts of the image in quick succession, and your brain blends them together to create a colour image. If you swish your vision across a DLP projected image, you'll get that RGB effect because your eye has moved between the different colours being projected. [This]( URL_0 ) is a video of a DLP projector image slowed down massively."
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7if402 | Don't Multi-Band Equalizers Ruin the Studio Mastering of a Music Album? | Technology | explainlikeimfive | {
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"Yes and no. The studio mastering is designed around the balance of the various parts of the music. You're not just raising or lowering a frequency band - you'd be raising or lowering a specific instrument in relation to other instruments. However, no studio can possibly create music appropriate for all spaces. The space you're listening to the music in has a certain response, dependent on the frequency, based on the materials and geometry of that space. So even though the master is 'perfectly balanced', it might not *sound* perfectly balanced in your space because certain frequencies are getting reflected/attenuated differently than others."
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7ig9qj | Why it is faster to charge a battery from 0-50% versus 50-100%? | Technology | explainlikeimfive | {
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"If you're trying to pour milk into a glass to make it exactly full, you pour faster when it's empty, and then slow down as you get to the top. The same way, your phone will do a slower charge mechanism to the top percentage (usually 80-100%). The charging mechanism may actually be damaging if it can't actually offload the power into the battery.",
"/u/Xelopheris is right and beautifully ELI5d it, let me just add some detail for ELI13+. Currently most used batteries in phones, laptops etc are Lithium-Ion or Lithium-Polymer. This type of battery is one of the best from currently available ones, because it can store much more energy in given volume or weight compared to other types. But, this battery technology is very sensitive to over-voltage. If you have a LiPol battery and supply more than 4.2V to it (or drain it to less than 2.7V), unwanted chemical reactions start to happen inside it, which can cause battery damage, or internal short-circuit, overheating and quick release of all its energy (\"explosion\"). I think we can agree that nobody wants their batteries to explode or damage themselves, therefore the charger is designed in a way that makes it sure that a higher than 4.2V voltage is never applied to the battery. If your battery is drained (around 3.2V), the difference between max charging voltage and the battery voltage is 1V. But if your battery is almost full (4.1V), the difference is just 0.1V. If you remember something about Ohms law, it might help, but if not, just believe me, that you can achieve 10x the current with 1V compared to 0.1V, so the battery can be charged with much greater current when empty. Now, batteries also have a max safe charging current, so that needs to be limited too, and that's the reason why charging fully drained battery isn't 10x (or more) faster than almost full one, but that's another matter."
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7ihxex | Why do freeware programs almost always try to install toolbars, bing, antiviruses, and other junkwares? | Technology | explainlikeimfive | {
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"If you don't pay for a product... you are the product. Those creating freeware aren't charities -- they are trying to make money! So they are trying to get you to install something they either earn a commission for getting it installed, or they hope to make commissions on clicks, etc. form the toolbar or whatever that you install. That's their business model.",
"Same reason most laptops come with a bunch of useless bloatware. They get paid to and it drives the costs of the product down. In the case of freeware, the costs are driven down from \"something\" to \"free\".",
"Freeware especially, seeking to offset some of their costs of development and distribution, if not gain some capital, will make deals with companies to package their promotional programs with the freeware. Not satisfied with the promotion from their toolbars, or other junkware, these companies will include spyware with it.",
"It's important to distinguish a true \"freeware\" program, where the author(s) and copyright owner(s) let you use the program expecting nothing in return, and what you've discovered- **adware**. Adware is a general term for programs that \"pay for themselves\" through intruding on, modifying, and monitoring your activity. They show ads to you, and advertisers pay the program's owners in return. Other companies may pay them to bundle their software with the program- Adobe bundling McAfee junk with Acrobat and Flash is probably the most familiar example. Still other programs take making money off you into their own hands, and these you could consider as spyware / malware! When you install a program, you are trusting the authors that the program is safe and friendly. That's not always true. These programs can spy on you, your browsing activity, and steal your information. They can redirect you to other sites. They can install more complex programs to eventually take over your computer and make it part of a botnet or ransom your data, both of which are very lucrative. In summary, these programs aren't free! You're being taken advantage of in some ways that you can see, and some ways that you can't. In fact, the cost is much higher than any use you might get out of these programs- you may lose your money, your identity, and may have to rebuild your entire computer."
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7ik7z5 | How was weather forecasted and predicted by meteorologists before the invention of radar and satellites? | Technology | explainlikeimfive | {
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"Using historical data, barometers, horse hair (for humidity), thermometers and hunches. And their predictions were about as accurate as you may guess. Certain weather phenomenon had certain precursors in certain places, but the level of knowledge we have now wasn't even available with radar and satellites -- it took computers and networked communications to pull all that together into something really useful.",
"One thing that is still today a important source of weather data is observations by weather stations. We have had the ability to transmit observation since he telegraph was invented Knowing what the weather is in the direction the wind comes is important. Weather observations form ships and land station in the Atlantic was a important advantage for the allies in WWII. Germany put for example a automatic weather station on Labrador in WWII and had manned outposts in arctic for weather observation. A part of the success of the D-Day landing in France was that the allied knew that there would be a day with good weather where the German did not know that ans predicted bad weather and troop stood down and seniorofficers wen away for the weekend. All that was before the first satellit and weather radar"
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7ilg18 | Why do video games all have such similar bugs? | Why do video games, made for years and years, by different companies all over the planet tend to have the same sort of bugs and technical difficulties? For instance, falling through the map, items floating when they should be attached to someone or in their hands, ragdolls becoming kites that fly around. | Technology | explainlikeimfive | {
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"because developers don't start truly from scratch every time... even if their **code** is written from scratch, the **ideas** for \"how do i check what's bumping into what\" \"how do i make something ragdoll\" all tend to be implemented in similar ways. Someone at some company years ago figured out a good way to do it and they're just tweaking that same strategy rather than waste time inventing their own.",
"Modelling collision can be done in several ways. You can do it in a way which is basically perfect in terms of not having glitches of going through floors, etc., but it would require vastly more processing power and you would not be able to do it in real time for a complicated game. Instead, they cut corners, lots of corners, with the calculations. Almost all of the time it works fine, and the performance is orders of magnitude better. Because different developers use the same shortcuts to get to where they want to go, they tend to have similar issues."
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7innhg | What makes full-motion video "full"? | I've seen the term "full-motion video" for a while. Why do we call it "full-motion"? Isn't it just "video"? | Technology | explainlikeimfive | {
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"The term started in 1983, when most video game graphics were a fixed image (\"background\") with a little bit of moving stuff (\"sprites\") put in front of it. They really weren't full motion, so this was a contrast."
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7io2el | Why is email free to use? How do they make up the costs to running servers, staffing etc... | Technology | explainlikeimfive | {
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"Modern webmail services aren't really free, they're ad-supported. It turns out that email isn't that expensive to run, and most of the companies giving you \"free\" email have other sources of income that they use to make most of their money, so they run the email to keep you tied in to the rest of their ecosystem and making them more money from serving you ads and you using their other products.",
"Email wasn't really free. In the past, your email was usually provided by your internet service provider so it was basically a part of your internet package. Webmail sites such as Hotmail only gave a small free mailbox (something like 10mb), but if you wanted something bigger you had to pay them. Google really revolutionized Webmail by giving you a whopping 1gb of storage for free. As in other Google services, Google made money from premium services and ads.",
"Once a person has email, they are then able to email all those e-businesses, and can order products over the internet, collectively generating countless billions of dollars in annual commerce. It pays to get people started on this for free. The fact that they can also email their friends and relatives to engage in inconsequential chatter does not really matter. Even then, their inconsequential chatter could include recommendations about commercial web-sites as well. Yes, I shopped at Amazon and I got exactly what I wanted! It was wonderful! Aside from that, your free email is not entirely free. You do have to subscribe to an internet service provider of some kind. Someone connects you to the internet, that is not free. That is where the money comes from, to pay for servers, staffing, etc."
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7iocf6 | In the chess games between Google's AlphaZero and Stockfish 8, why is each game different? Why isn't each game just the same every time | Technology | explainlikeimfive | {
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"Ahoy, matey! Yer not alone in askin', and kind strangers have explained: 1. [ELI5: Why a chess computer doesn't respond the same way every time to the same attack pattern. ]( URL_2 ) ^(_5 comments_) 1. [ELI5: Why does a computer use different openings when playing chess? ]( URL_0 ) ^(_7 comments_) 1. [ELI5: If I let two chess engines play each other 100 times, how do they play 100 different games if there must be one optimal game? ]( URL_1 ) ^(_10 comments_)",
"In the evolution of AlphaZero's and other AIs brains, they add a little bit of randomness into it, analogous to how humans and other species have adapted over the years, because some random mutation might facilitate reproduction and survival much better, so that feature becomes more pronounced over time. In the same way, until the game is completely solved, they continually add a little bit of randomness so that for example the program doesn't get caught in the same trap over and over again, whats called a local minimum."
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"https://www.reddit.com/r/explainlikeimfive/comments/1ts924/eli5_if_i_let_two_chess_engines_play_each_other/",
"https://www.reddit.com/r/explainlikeimfive/comments/2v719l/eli5_why_a_chess_computer_doesnt_respond_the_same/"
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7iody6 | how pulse detection apps work | I have a heart rate monitor app on my phone which works pretty gosh darn well. I place my finger over my phone's camera and LED flash and it accurately measures my heart rate in real time. My nurse girlfriend has taken my actual pulse at the same time and it's always very close. So how does it work? | Technology | explainlikeimfive | {
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"Try this: open the camera app on your phone and start recording video while turning the flashlight (LED lamp) on, and then press your finger on the camera lens. You will see a blurred image of your finger and if you look closer you'll see a slight pulse in the color. Thats your heart beating. It works because the flashlight will penetrate your skin and scatter all the way around in your finger including your artery, and some of the light getting back to the camera gets slightly dimmer when your heart pumps.",
"Basically, they shine a light through your skin, and then using the camera they measure changes in reflected light that can tell them how fast your heart is beating.",
"BTW heart rate monitors on smartwatches use the same principle. In this case, tiny green light emitters, and tiny light detectors. Why green light? Better contrast with the red blood pulses."
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7ionrz | How did early humans survive in cold weather before the invention of clothes? | Technology | explainlikeimfive | {
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"Humans originated in warm locations, and when it was cold, that was usually night when they were in their shelters anyway. Evidence supports the hypothesis that humans didn't move to icy-cold locations until *after* the invention of clothes.",
"According to the most widely-accepted theory, for most of the existence of our species we didn't live in areas that were cold. Homo sapiens evolved in central eastern Africa about 500,000 years ago, and remained only in Africa until about 150,000 years ago. There's also no particular reason to believe that early humans were unclothed. By definition all members of homo sapiens in the last half a million years have had the same capacity for intelligent thought and reasoning that we do, so it's entirely within possibility that when humans did start to migrate to colder parts of the planet they used animal skins and furs to keep themselves warm.",
"Before the invention of clothes (even in their most primitive form, which was basically just the scraped hide taken off an animal) people did not survive in cold weather; they evolved as tropical animals living in tropical climates.",
"Although the oldest fibers known are about 34,000 years old, the oldest jewelry is [74,000 years old]( URL_0 ) to [100,000 years ago]( URL_2 ). If humans were wearing jewelry, you can bet they were wearing clothes. [Humans didn't leave Africa]( URL_1 ) until 200,000~150,000 years ago and there weren't many really massive migrations until 60,000~50,000 years ago. We stayed put where is was warm for a very long time. So, by the time humans start to get into cooler areas, it's pretty clear we have clothing of some sort.",
"Humans evolved in warm/hot regions of Africa. They did not move into cold regions until after they invented clothing and harnessed the use of fire.",
"What people are saying about when humans left is true, modern humans started wear clothes about 170,000 years ago well before leaving Africa. However, other hominids were living outside of Africa and tools to take hide from animals show up about 780,000 years ago.",
"The first hominin species to move out of Africa was Homo erectus, around 1.6 million years ago. Fast forward a few hundred thousand years, Neanderthals came about in Europe. Their bodies were specially designed for cold weather, with short, stout stature, thick muscles, and large noses. There is evidence that they created clothing, but their bodies were very well adapted to cold climates as well which allowed them to survive the cold.",
"The first explorers to the tip of South America recorded that the natives there could make fire very quickly, only made crude shelters, and wore almost no clothing. I do not know how they did it but I trust the observations. A fire, sometimes two fires, can warm a person. People can stand a lot of cold without dying. I would definitely try to fashion clothing myself. [Despite the extremely cold climate in which they lived, early Yaghan wore little to no clothing until after their extended contact with Europeans.]( URL_0 ) They were able to survive the harsh climate because: They kept warm by huddling around small fires when they could, including in their boats to stay warm. The name of \"Tierra del Fuego\" (land of fire) was based on the many fires seen by passing European explorers. They made use of rock formations to shelter from the elements. They covered themselves in animal grease.[6] Over time, they had evolved significantly higher metabolisms than average humans, allowing them to generate more internal body heat.[7] Their natural resting position was a deep squatting position, which reduced their surface area and helped to conserve heat.[6]",
"Humans were not living in places that got that cold until well after they started wearing furs to protect themselves. At first pelts were likely worn to protect our skin from bushes and plants that we would brush against while running after prey.. or perhaps to help us \"blend in\" while hunting. They most certainly were not worn to help protect us from cold weather until we started living in colder places.",
"By avoiding that degree of cold. We weren't able to survive in those climates until some wise ancient humans started covering themselves with animal pelts"
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7ioo56 | How is it possible that when talking on the phone, person A can suddenly lose signal and not hear person B, but Person B can hear person A perfectly well? | Technology | explainlikeimfive | {
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"text": [
"Modern communication systems use digital streams of data to connect calls. In most systems the signalling (setting up a call, putting it on hold, ending a call) is sent using SIP while the voice itself is sent in RTP (real time protocol) streams. The RTP streams are one way. So you have a dream from you to your destination and they have one back. It is possible that one of these streams gets disrupted, leading to one side hearing the call but the other not. Edit: I'm staying dreaming!",
"Transmitting and receiving are on different frequencies negotiated by the cell tower. Sometimes there will just be interference on the receiving channel, sometimes just the the transmitting, and sometimes both. If you are in a densely populated area, your signals may be even going to different towers. There are a lot of things that can go wrong.",
"Compare it to regular wifi: Have you ever noticed that you sometimes can detect wifi-networks with low signal strength but that you can never connect to? The wifi router usually has a much better antenna and transmitter, while your phone has a built-in much smaller one. So the wifi router is able to scream, but your phone can only whisper in response. In the cellphone case, the cell tower is the router. So person B can hear person A because the tower is able to transmit (scream) through the interference, but person A cannot hear person B, because B's phone cannot transmit back through the same interference. I.e. these kind of problems are usually only on one side of the call, between A and the tower, or between B and the tower (in this case between B and the tower). So if you are talking on the phone, and you can hear the other person well but he can't hear you, the problem is most probably on your side of the call."
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7ip7sm | How is an ultra-sound tech able to calculate the weight of an unborn baby? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Cardiac Sonographer here, with my little bit of experience in OB sonography I can tell you it's a calculation based on four measurements. Femur length (FL), head circumference (HC), abdominal circumference (AC), and the biparetal diameter (BPD) which all give you an estimated fetal weight (EFW). I don't remember the actual formula but there are calculators online to punch your info into to get your result. As with most measurements with height and weight (especially with children) there are standard deviations and percentiles Sonographer come up with based on an average bell curve.",
"They measure certain things and compare that to an average. Aka they take an educated guess."
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7ipx06 | Why do older people have such problems with technology? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"When you have spent decades becoming familiar with certain kinds of technology, and then it all changes, it can be hard to adapt. When I first learned how to use a telephone, I could use any telephone anywhere, since they all worked exactly the same way. Now every brand of telephone has its own particular operating procedures. I find that this makes the world very complicated. That is aside from the fact that some old people do become senile, and consequently have difficulty understanding anything. As you age, all organs of the body tend to wear out, and that definitely includes the brain."
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7iq66u | How do cords get tangled? | Technology | explainlikeimfive | {
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"text": [
"This is actually something that physicists have studied. Long story short, wires, strings, and cords tend to fall into rest in loops and those loops, and the ends, tend to fall in to other loops easily when disturbed. But this is just the set up. When you come along and pick it up, if you pick it up in the wrong place, it's like pulling your shoe laces tight when you are tying your shoes. You have picked it up in a place such that you have pulled one loop through the other or one end through a loop. Unaware of what you have done, you start grasping other areas as you try to figure out this seemingly messy puzzle, ultimately making the situation worse. I've seen what I've known to be neatly coiled wires go from slightly tangled looking to actually tangled because the person picked them up in the wrong place and became \"disoriented\". The best away to avoid things coming tangled is to wrap them the right way to begin with and use ties to keep everything in place. URL_0 For the alternating coil wrap, pay attention and make sure you actually alternate or you will end up knotting it (yes, you can knot a cable without touching the ends). For christmas lights I recommend multiple ties because the lights will catch on other loops and can pull them through and catch on the other lights, causing a tangle, when you are handling them. When you go to uncoil things, make sure you are starting from the right end in the right orientation."
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7iqipj | Why do bladeless fans have a large open space in the middle? | I looked how they work up and it seems to me like it's wasted space and a small one with equal circumference would work just as well, of any shape. | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"These fans work by directing high pressure air into a ring. The high pressure air drags the air that's in the ring forward with it. Conservation of momentum gives a larger amount of air moving more slowly (and thereby quietly). A smaller one wouldn't accelerate as much air, so it would be a small amount of air moving faster. This would cause more noise."
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7ivr8d | Graphene, Graphite, and why one is an amazing super-material and the other is pencil lead and skateboard layers? | Technology | explainlikeimfive | {
"a_id": [
"dr1qgt6"
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"text": [
"*Graphite* is many *graphene* sheets layered on top of eachother. Graphene is only a single atom thick, and this gives it some odd properties because so many electrons are exposed in identical configurations. You can't make a bulk material out of it though, stacking them up allows the electrons in each layer to interact and changes the properties."
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7ixq4r | For fires as extreme as those occurring in California currently, how are these fires put out? | Technology | explainlikeimfive | {
"a_id": [
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"dr26tqm",
"dr28ind"
],
"text": [
"Actual California firefighter here. We begin by cooling the fire where we can access from an anchor point like a road. Once the fire line is cooled by air drop or hose line we put in control line by hand. It doesn’t have to be much, usually only a few feet wide. The area behind the control line is cooled further and mopped up. Hotshot crews burn out areas of unburned fuels from pre established control lines either hand made or existing roads, rivers, etc. thereby bringing the fire to more advantageous ground when we choose. Weather plays a big part in where and when we can really attack a fire. As a guiding principle we usually attack large fires from the flanks or sides. Making a frontal assault under the wrong circumstances is suicide so we are careful when we use that tactic. We don’t “draw a line in the sand” so to speak, but we can have a real measurable influence on the fire’s growth and where it stops.",
"In general they arn't. When they can they will try and keep them away from houses, by clearing brush, and dumping water/anti-fire chemicals, but most of the time they just let them burn out.",
"The most important step in fighting wildfires isn’t putting out the fire, it is containing it. The thing is that we generally don’t have nearly enough and fast enough access to water to put out these fires. So instead what we do is we try to do is surround the fire. Fire needs fuel to spread and if we can surround the fire with a small 20 or so meter thick area of no fuel (which I will call a wall) where there is no fuel, it effectively becomes contained. Wildfires tend to be kind of like a ring, the center is all burned, it consists of basically all hot coals and embers, while the surrounding part is actually what is burning. So the strategy here is twofold, have people surround the fire, generally by cutting down trees and even using small scale fires to burn out the fuel there. This is what percent containment means, it is the percent that this wall has been created. Beside that, we also have other crew actively battling the ring of fire where there is a risk that the fire will reach the wall before it is actually built, buying time for this wall. This is particularly true near residential areas, where if there isn’t enough space between the fire and the buildings to construct this wall, efforts are concentrated there to slow the fire enough that a wall can be constructed there. It is a losing battle, the sheer scale of the fire is too large to completely stop, but it buys time. After that, the fire runs out of fuel and it effectively becomes cleanup, we need to wait for the hot coals to die down and make sure that there isn’t any place that the embers may penetrate and start a fire in a new area."
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7iyhj3 | Remember when point and shoot cameras had a flash that made a high pitched tone when you turned it on? What made that sound? What was the purpose of that sound? | Technology | explainlikeimfive | {
"a_id": [
"dr2crdl",
"dr2c6td"
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"text": [
"The whining you hear is the mechanical vibration of circuit elements from the very fast voltage stepping. Modern camera flashes have changed electronics and often don't do this anymore.",
"That was probably the sound of a capacitor charging up. Then the camera has enough power for one flash. Then it charges up again. Capacitors are a way for an electronic device to get steady energy and at high bursts. It acts like a battery being quickly charged and discharged."
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7iyvic | Which countries don't rely on the US for their internet? | Technology | explainlikeimfive | {
"a_id": [
"dr2g3m6"
],
"text": [
"Net neutrality won't really affect other countries. Comcast, Verizon don't control the backbone and messing with the backbone would quickly get America as a whole thrown off the internet. As a general rule most big/wealthy countries control their own internet. China for instance blocks most foreign web sites for political reasons. If America did something stupid they could have their own internet up and running in a few days. tl,dr - America is not in a position to charge other countries for specific content. If we tried we'd quickly find out how impotent we are in the modern era."
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7izb52 | What is a laser printer doing when it is making all those noises but not printing? | Technology | explainlikeimfive | {
"a_id": [
"dr2ipfo"
],
"text": [
"Laser printers operate by attaching ink to a spinning metal drum. The paper then passes under the drum as it rotates, transferring the ink to the paper. In both cases (ink on drum, ink on paper) a combination of magnetism and electronic fields (which are the same thing but that’s for another ELI5) and heat are required to make the ink, which is responsive to magnetism/electricity and heat, attach to the surfaces. You can think of it like heating up a decorative patch with an iron to make it “stick” on a jacket. In order to get a large amount of magnetism/electricity gathered together an electrical storage device, called a capacitor, must charge up with electric current. In the case of heat, similar heating elements must warm up. So this is why you hear mechanical devices whirring and fans blowing and things rotating."
],
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7j1o07 | What is Pi-Hole, what does it do? | Technology | explainlikeimfive | {
"a_id": [
"dr2y7so"
],
"text": [
"It’s a really awesome and effective network-wide ad blocker. It pretends to be a DNS server and instead of returning the ip of a requested ad server, it instead returns its own ip. Then when the browser requests the ad, it returns a 1x1 pixel webpage. I installed on on my home network and it even blocks in-app ads on my iPhone. I no longer get the commercials at the beginning of YouTube videos on my smart TVs."
],
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7j76mn | How do heat seeking missiles work? | Technology | explainlikeimfive | {
"a_id": [
"dr473k5"
],
"text": [
"In the simplest terms, there is an infrared (heat vision) camera at the front of the missile attached to a computer, which is attached to the missile's control fins. The computer adjusts the fins to keep the brightest heat source the camera can see in the center of the picture."
],
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7j7zqe | How do humidifiers work and why is the vapor not hot? | What exactly is produced by the humidifier? It's not hot like steam should be but it also seems too fine to be water mist. | Technology | explainlikeimfive | {
"a_id": [
"dr4c5rg"
],
"text": [
"It is water mist. Usually you just run water through an atomizer to make it into tiny particles. You can do basically the same with a fan and a bowl of water. The fancier ones run it through a compressor thing to make it look more misty, but it is just water"
],
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7j9ml3 | What are CASE tools in programming and how are they used | *Title* | Technology | explainlikeimfive | {
"a_id": [
"dr4uvz9"
],
"text": [
"CASE, Wow! Haven't heard that in a while Computer Aided Software Engineering. Back in the days when software was rarely properly designed, when it was, it was usually with a pen and paper on a spare piece of paper. Then someone came along and said, 'Let's use software to design our software!' and so we started using stuff like Visio and Rational to model the interfaces and classes and data we were going to implement in code. These days Agile has taken over and Aglie says we should let software design evolve naturally rather than designing everything up front so CASE tools aren't used that much anymore"
],
"score": [
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7jakm0 | What’s a Webhook? | Technology | explainlikeimfive | {
"a_id": [
"dr4ukxl",
"dr4whlh"
],
"text": [
"Its a way for one server to subscribe to events on another. Lets say I had a server that parsed Reddit comments, for some reason. I *could* check every 5 minutes to see if there are any new comments, but then I could be up to 5 minutes out of date, and if no new comments where created its wasted time to check. Instead (if Reddit offered it) I could subscribe my server to their webhook, which is basically me asking reddit to send a message to some URL every time an update happens.",
"Lets imagine you have a friend called Tommy (the service sending you a webhook). You tell Tommy that when school finishes or the rain stops (actions to cause a webhook), he should come to your house and ring your doorbell (your server / application), and then you can make a decision based on those actions (your application logic). :)"
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|
7jdodx | Shortened URLs like goog.le, URL_1 , URL_0 | Technology | explainlikeimfive | {
"a_id": [
"dr5ih8r"
],
"text": [
"Just because a domain is registered in Italy does not mean that the traffic is routed there. Remember, domain names are created for humans. Computers use IP addresses, not domain names when it comes to actual traffic routing. There is a service, called a DNS, that your ISP provides that translates domain names into IP addresses. All that the suffix of the domain name means is that the country in question is in charge of issuing the domain. It has nothing at all to do with routing."
],
"score": [
13
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|
7jer5y | How do public terminals wipe everything and reset every session? | Technology | explainlikeimfive | {
"a_id": [
"dr5st7j"
],
"text": [
"depends on how the IT dept setup the terminal. back in the day, the entire computer ran off a static disk image. after every logoff, the entire computer wiped itself and restored from the image. nowadays alot of it is just storing session data in a container. once session is gone, toss the container away. when you login, make a new container."
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|
7jhjco | How does a gpu work? | Technology | explainlikeimfive | {
"a_id": [
"dr6g1o8",
"dr6grp0",
"dr7hppr"
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"text": [
"I work in ASIC design (mostly analog and layout design, so bear with a relatively imprecise but hopefully mostly accurate answer) 1. a gpu core is designed to be very good (fast) at solving a certain kind of problem, namely things like simple addition and scaling, it pays for this by not being as general purpose as a normal computer cpu - which is in turn not as fast as a gpu can be (at certain problems). 1. GPU cores are relatively easy to pack on a chip because they are individually small compared to a CPU core, which lets a single chip work on multiple problems at once, if used correctly by software. For things like graphics processing, you need to do various types of scaling and addition problems for each frame you draw. A single GPU core is optimized for this problem. By using the multiple cores on a single chip/card (or multiple cards, even), you can work on multiple pieces of the frame at once, letting you draw more frames faster. The data that makes up these frames has to be stored in a buffer (or holding area) of some sort. This is why GPUs have large banks of high-speed memory - so that they may store the large amount of data that makes each frame and send it to the screen once it's ready, and do so quickly.",
"A normal computer (a CPU) is like a stream. The flow of instructions happen in sequence, one after the other. You can make the stream's path as long and as complicated as you want, and it's very easy to control. This is great for when you need to do complicated logic. The only problem is that the flow of water through the stream is slow. A GPU is like a tsunami. It can do a great many instructions at once! You can't make a long complicated paths of logic, but you can do a flood of short and simple operations very quickly. This is great for when you need to do graphics operations, like computing the lighting on millions of pixels sixty times a second.",
"The other answers explain it very well, but I'd like to go into a bit more detail. The main job of the GPU is to execute what are called *shader-programs*. These are usually \"small\" programs designed to do a very specific job during rendering. A very basic example would be the Fragment Shader (or Pixel Shader), that is called toward the end of the graphic pipeline (the process by which an image is rendered on your screen), and it does nothing other than being called for every pixel that should be rendered and output its color. Now, one thing you want the GPU to do in the Fragment Shader is compute lighting/illumination. Not to go into too much detail, but imagine you have a certain algorithm that computes a \"brightness\" value for your pixel. This algorithm will be repeated for each pixel, bearing the same instruction just different data (it's the same algorithm after all), and if you managed to construct your algorithm in such a way that it includes no conditionals (constructs like *if*/*else*), the GPU knows exactly what do to each time the shader-program is called, *before it even calls it*. This means, the GPU can build a pipeline with the instructions written in it, and then execute that pipeline for a number of pixels in parallel. Each instruction that is executed accesses different data and produces different results, but the instructions for each pixel are the same. This is called SIMD (single instruction, multiple data) and leads to a highly parallel execution of your shader for each pixel. Modern GPUs can run that shader for hundreds/thousands of pixels in parallel. In addition to that, they have dedicated circuits for certain math problems that appear frequently in 3D-geometry. Examples would be the Dot-Product, the Cross-Product or Matrix-Multiplication, those are basically hard-wired, removing the need to transfer values into different registers multiple times on each operation."
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7ji69c | The number of videos on YouTube is vast. Is there any risk of losing this data? What would need to happen for data loss to occur? | Technology | explainlikeimfive | {
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"The data is almost certainly duplicated/spread across multiple drives and multiple datacentre locations, with more frequently accessed data (popular videos) spread even more so that more people can read that data at once. I haven't read any specifics on Youtube but I expect their data redundancy is top notch. It could still be lost, but the chances are low. If the data is only on a single drive, then all it takes is for that drive to fail and then the data is lost. This is why Youtube will spread the data across multiple drives. But something could still go wrong in that specific physical location that causes the loss of multiple drives, so mirroring the data to other data-centres across the world helps mitigate that risk as well. It would be particularly unfortunate and unlikely if every single piece of data relevant to the file were all lost at the same time. A different possibility for data-loss that should also be considered is that Youtube could decide to purposefully get rid of certain particularly old/low value content at some point in order to save costs. I think it is prudent to keep a copy of very important data yourself and not 100% rely on online storage.",
"The data is replicated amongst a vast amount of servers so the only risk of data loss at a noticeable scale will require server failures at multiple locations at once. Basically they keep copies of their eggs in many baskets."
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7jimdp | Why must phones be turned off at gasoline stations? | Also, why do people ignore this warning ? edit: before posting, I searched reddit for the answer to my question but got nothing. However when I did a google search, a number of posts similar to mine popped up. I checked them out and found out that they were a few years old. Now I'm wondering if today's answers would be any different to a few years ago. | Technology | explainlikeimfive | {
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"There was a fear of exploding cellphone batteries igniting the gas fumes. Most people ignore it because the chance of it happening is actually quite low.",
"The cell phone causing a fire is a common myth. Every time this question gets asked people point out the myth busters episode. Cell phone and their lithium battery catching on fire is a fairly rare event. The biggest risk with a cell phone is driver inattention. Walking into moving cars, forgetting the nozzle is in the car and driving off, snapping the breakaway on the hose.",
"It started off years ago when cell phones were quite new. It coincided with some explosions at gas stations where the causes weren't 100% certain. One possible cause was electrical discharge from phones, and since the equipment was new and coincided with the rise in explosions they were banned. None of the incidents have been proven to be due to cell phones however. They also noticed that the overwhelming number of cases were in the US. US is/was pretty unique in that you don't have to hold the pump the whole time. It turned out the biggest risk was static electricity due to people sitting down in the car while the car continues to fill. By then laws had been passed and gas stations were restricting the cell phones. That makes it nigh on impossible to remove the rules when there remains a theoretical risk of a cell phone causing the same damage.",
"Gas stations that used to have no cell phone warnings at the pump, that I frequent, have removed them. It was essentially a hoax. Its virtually impossible for a spark from your phone to ignite gas vapors in the air. URL_1 Mythbusters tried, really really hard to make it happen, and couldn't. URL_2 URL_0",
"I don't think it is as big of an issue as it used to be. But the issue is that a static electricity shock can ignite the fumes. The same reason you aren't supposed to get back in the car while fueling.",
"People once believed (and often still do) that there was a possibility they could ignite gas fumes. Cell phones might be ubiquitous now, but in the 1990s they were almost magic, and people believed a lot of silly things about them. It is theoretically possible for this to happen, but gas fumes are much, much more like to be ignited by a hot engine or a faulty connection than by a phone."
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"https://www.snopes.com/autos/hazards/gasvapor.asp",
"https://www.discovery.com/tv-shows/mythbusters/videos/cell-phone-gas-station-minimyth"
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7jkfx0 | Why aren't noise cancelling headphones as effective in cancelling high pitch sounds as their in cancelling low pitch sounds? | Technology | explainlikeimfive | {
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"The way noise cancelling works is that it has a microphone pick up some noise and then a speaker produce that noise phase shifted 180 degrees. The resulting waveforms precisely cancel out. However, the microphone can only pick up the noise as it's passing by and there's a delay before it can generate the phase-shifted sound. This means that you have to 'guess' what the future will hold in some sense. High frequency waves embed more information and shift more often, meaning it's a lot harder to make guesses about them than low frequency waves.",
"_Actual ELI5_ Have you ever tried clapping opposite to someone else? I mean clapping exactly when the other person has their hands apart, getting your hands apart when they clap? It's really hard to do. You can usually only do it when the other person (or, worse, crowd) is clapping pretty slowly. When they're clapping very fast, or there's a lot of them clapping not-exactly-in-sync, it gets quite a bit harder. Noise cancelling headphones try to do exactly this but with sound waves. Lower frequency sounds _clap_ slower and are easier to predict. Higher frequency sounds _clap_ faster and are harder to predict.",
"Low frequency sound waves are generally transmitted better than higher frequency sound waves due to several reasons: (1) Better diffraction, since lower frequency sound means longer wavelengths and longer waves bend more easily around obstacles and have more ways to reach their destination, (2) The human ear is most sensitive to frequencies around 2-2.5KHz, but when it comes to lower frequencies, the ear is not the only thing receiving the sound. Bones and organs can also feel the vibrations of a low freq sound (ultra heavy bass may even interfere with the working of the heart), (3) majority of songs have bass frequencies boosted. Since the ear is most sensitive to 2-2.5KHz sound, the lower frequencies need extra energy (i.e. higher amplitude) for their bass to be perceived \"adequately\" (and what is perceived as adequate bass today is most definitely more powerful than adequate bass 50 years ago).",
"Low frequencies are more spatially uniform due to their longer wavelength. They travel through most materials without reflection * * , and reflected waves interfere on a much larger scale than that of your head or ear * * *. If you ever listened to a pure high frequency sound, you know that moving your head even a few millimeters can change the intensity due to wave effects. So using a microphone to pick up the sound, and then invert and send to your ear is much less useful. The sound at the microphone is not exactly the sound you hear inside the ear, and even the sound created by the headphone is not as predictable and will generate some noise instead of canceling it. ** This is why low frequency sounds are so hard to remove, from the cabin of an airplane, for instance. It passes through the sound deadening materials. *** This is why a subwofer can be anywhere in a room - your ear gets no directional information by moving around or reflections.",
"The simple answer is because that's what they were originally invented for, engine noise. A better answer involves math. Noise cancelling headphones work by adding \"negative sound\", sound that is 180° out of phase. So let's assume that the noise cancelling headphones have only one microphone and it's located at the same place as the speaker, about a centimeter from your ear, and we'll ignore the passive effects of the headphones and your ears, just treat them both as points. Ideally, the sound and \"negative sound\" reach your ear together, 180° out of phase. 2cos(180°/2) = 0 no sound. First, let's ignore time and consider direction. If the sound wavefront comes in inline with the headphone a your ear, then there's a 1cm difference between the headphone and the ear. If it comes in at a 45° angle, there's only a 0.7cm difference, but the \"negative sound\" still has to travel the whole 1 cm because it's coming from the headphone. At 200hz that 0.3cm difference is a 0.6° difference, basically nothing, but at 2000Hz its a 6° still tiny but 10 times less tiny. Now assume there is a 0.1ms delay between the headphones hearing the sound and producing the \"negative sound\". At 200Hz this leads to a 7.2° lag. 2cos(187.2°/2) = -0.126 a 87.4% reduction, pretty quiet. At 2000Hz however, that 0.1ms is a 72° lag. 2cos(252°/2) = -1.175 the headphones are so far from their intended phase that they're actually making the sound 17% louder. That 10x difference in lag let to a more than 10x difference in noise reduction because the cosine function is non linear. TLDR at higher frequencies, small errors make bigger differences."
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7jl14o | How do game developers link between graphics and code? | Technology | explainlikeimfive | {
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"This is a massively complex question for which any answer suitable for ELI5 isn't really going to do justice to the substance of the subject matter. Think of the graphics engine in a game as a machine that builds Lego sets on demand. When given the instructions to build a set, it will throw out the set it just built and build a new set from scratch, which it can do dozens of times per second. In order to do this, the machine has access to a massive, well-organized Lego collection. This collection has an infinite *number* of blocks, but a defined, finite number of *kinds* of blocks. In other words, you only have so many different kinds of blocks, but you have as many of each of those kinds as you need. The way this metaphor works is that the frames displayed on your screen are \"Lego sets,\" and the \"Lego blocks\" are the game's \"art assets\", i.e., files saved on your hard drive that can be invoked on an as-needed basis. As the game displays frames (i.e., builds new Lego sets), it's programmed to invoke specific art assets under specific conditions and with specific parameters (i.e., pick the right blocks from the collection). One of the big tricks is changing those conditions and parameters as your perspective changes, whether that's simply moving your most or walking around the map. But that programming will basically tell the graphics engine what art assets to invoke and under what terms they should be handled (i.e., write instructions for new Lego sets on the fly). Any explanation much more technical than that is going to involve too much detail for ELI5."
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7jlhdz | How does the Google Maps 'Popular Times' feature work? | They have this feature even for the smallest shop in the World, but how does it actually work? | Technology | explainlikeimfive | {
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"billions of android devices all send geolocation data back to Google. if lots of devices are in the area of the shop, then it's an indicator it's busy at that time of day."
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7jmsyt | What is it that the is microwave 'sensing' when you choose sensor reheat? | Technology | explainlikeimfive | {
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"That link covers most of it. The most common sensor in a microwave is simply a moisture sensor. Some higher end microwaves do have types of temperature sensors and there are even a couple out there with noise sensors to tell when the popcorn is done popping."
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7joarj | How do heat sinks like the ones on CPUs work ? | You put some paste on the cpu and then slap a huge aluminum(?) block with some copper tubes and a fan attached to it and all of a sudden it won’t melt anymore. Magic ? | Technology | explainlikeimfive | {
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"heat moves between two localities to move towards equilibrium. the CPU is really hot like 150+F. the heatsink is less hot like 120F. the CPU heatsink dissipates heat into an even bigger heatsink: your room's atmosphere where it's like 70-80ish F. and your room atmosphere mixes with your home's atmosphere which mixes with open air atmosphere.",
"The thermal paste acts as a thermally conductive filler. As the surface of the heat sink base and CPU lid aren't perfectly smooth, air bubbles would otherwise form, and trapped air is an extremely poor conductor of heat. The general idea of a heatsink is that heat passively flows from hot to cold. In this case, the hottest part is the CPU package, and the fins are passively or actively cooled by air.",
"Heat transfer is proportional to surface area & the material you're transferring to. It's *much* easier to transfer heat into aluminum than it is into air. Since the face of the CPU is very small, you want to hook it up to something that'll take as much heat as possible. The heatsink then creates a *lot* of area to contact the air, making it practical to dissipate the heat.",
"A heatsink is designed to increase the surface area of the object that needs to be cooled. Metal and water are great thermal conductors, but air isn't. So you create an object to spread the heat load more evenly and make contact with as much air as possible. You can do this with a big metal plate, which is what a lot of low power mobile devices use. For more serious cooling though, you use fins. Thin metal fins are allow you to create a lot of surface area without drastically increasing size of the heat sink. We then attach a fan so hot air is pushed out and a continuous stream of cool air is run past the fins. The copper tubes attached to some heatsinks are heat pipes. They contain a small amount of liquid. When this liquid hits the hot conductive metal plate on top of the CPU, it vapourizes, and naturally gravitates to the cooler end of the pipe, where the cooling fins are. It then condenses back into a liquid and repeats the cycle. This is somewhat similar to how a refrigerator works, except this process is entirely passive. You can also kick it up a notch to liquid cooling, which uses flowing water as the heat transfer medium. Neither traditional finned heatsinks or water cooling can cool a chip lower than the ambient air temperature though. For that you have to go to exotic cooling methods like phase change (an active refrigeration cycle), dry ice, or liquid nitrogen. None of which are really practical. The paste is thermally conductive ceramic compound. Sometimes mixed in with a small amount of metal that's exceptionally conductive, like silver. It fills in imperfections on the CPU and heatsink, to make the best contact and eliminate hot spots. These hot spots can damage the chip, so processor heat sink should never been installed without it."
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7joo96 | How do studios make such strikingly real animation? | How is the 'world' of a big-budget animated film created? Watching something like The Jungle Book, The Good Dinosaur, Moana, etc.. it looks like the most ridiculously immense and intricate process that I can't actually wrap my head around. | Technology | explainlikeimfive | {
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"congrats. you noticed. because it IS a ridiculously immense process. that involves HUNDREDS of highly skilled artists, and ridiculously smart software engineers working for YEARS. this is just one tiny piece of Moana. URL_2 one tiny piece of Zootopia URL_1 one tiny piece of Incredibles URL_0"
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7jqzjn | How do BIP39 mnemonics work? | So I got a hardware wallet for my different cryptocurrencies. How do we get from the mnemonic to a private key? How many private keys do I have? How does the software know my addresses? I understand the benefit of mnemonics, but I do not understand how this little phrase contains this much information and where and in which form the information is saved. What are those "/40/m'" things you can see sometimes? | Technology | explainlikeimfive | {
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"> How do we get from the mnemonic to a private key? > To create a binary seed from the mnemonic, we use the PBKDF2 function with a mnemonic sentence (in UTF-8 NFKD) used as the password and the string \"mnemonic\" + passphrase (again in UTF-8 NFKD) used as the salt. The iteration count is set to 2048 and HMAC-SHA512 is used as the pseudo-random function. The length of the derived key is 512 bits (= 64 bytes). [source]( URL_0 ) ELI5 version: hash the mnemonic as if it was a password > How many private keys do I have? The above process generates a single root, which itself generates chains of private keys. The number is essentially unlimited. > I do not understand how this little phrase contains this much information The mnemonic sets the starting point, from which math manipulates that number to generate the next number. You could think of it as the mnemonic generates a value X, and the math does some function like \"add 1 to get the next value\" (obviously the actual math is crazy complicated, but there's no difference to the computer, it's just running math code either way). > What are those \"/40/m'\" things you can see sometimes? Sounds like character escaping, but I'm not sure. Where are you seeing it?"
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7jrgk1 | How does Youtube monitor the millions of videos posted every day for things like copyrighted music, images, and also “advertiser-unfriendly” content? How does Youtube know if the subject matter of your video is “inappropriate”? | Technology | explainlikeimfive | {
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"A company like Youtube has too many videos for their own employees to monitor. Instead, there are two real mechanisms for youtube to monitor content: The first is crowd-sourcing and the second is computers. On a video, there's a little button to \"Report\". When a user clicks \"report\" a message is sent to a relatively small team of monitors who check the video to make sure it's OK and remove it otherwise. That's crowdsourcing, because the crowd of users is doing most of the work (identifying and flagging the bad videos). Similar to crowd-sourcing is the idea that the video creators, when they upload content, can tag their own videos with things like \"uses bad language\" or \"inappropriate for children\". A faster way to identify some problems is through computer software. Let's say we want to avoid duplicate videos, or we want to check for videos that are copyrighted: We'll compute some kind of \"checksum\" for the videos and compare it to a list of known videos. If the checksums are equal, the computer automatically flags the video and it's sent to that same small team of monitors to verify. Checksuming is why you see some videos on youtube from TV shows or movies with a boarder around them, or flipped left-to-right, to change the checksum and avoid this detection. There's also the emerging field of AI, where computer learning algorithms can be taught over time to recognize things like nudity or curse-words. In this case you take a small \"training set\" of known examples and train the AI algorithm, then set it loose on your \"working set\" of all videos. The AI will flag videos it thinks are like the training set, and the team of monitors will verify and take action. Sometimes, if you have enough trust in your AI program, you can skip the team entirely and just have the program delete videos directly (and then the creators would need to take action to save it, if they thought it was an error)."
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7js1jw | What is design and systems thinking? | I've referred to various definitions and examples but I don't think I still catch what it's all about. | Technology | explainlikeimfive | {
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"Most people tend to think of complex dynamic systems in terms of individual components, without fully grasping how they interact and the impacts of those interactions. Let's say you've got a team project due tomorrow. Collectively, your team needs to write a 20-page paper describing your work. So you divide the work up into 5 sections, assign everyone a section and you all work independently. Everyone finishes their work by the deadline and you're all set, right? Wrong. In all likelihood, none of you actually completed your task because certain elements of one section were dependent on the others - and you needed information from other group members to do a good job. The entire document as a whole needs review and markup based on standards established group-wide. Simply \"doing your job by the deadline\" in this case is a strategy that leads to failure. You need to come up with mechanisms for coordinating the work beyond this simplistic notion of dividing up the work. Moreover, you also have to deal with failure modes. Consider that slacker member of your group who never gets their work done. If they completely fail in their assignment, you'll lose points on your grade. So if the deadline is 9 am tomorrow, at what point will you need to do their work for them to complete in time? How do you communicate this to other team members so they're not doing redundant work? 'Systems thinking' is thinking about all of these issues that arise when coordinating different tasks and recognizing the inter-relationship between those tasks. It involves examining dependencies between tasks, and how unforeseen events can affect not just one particular task but all tasks in the system. A 5-person academic project is fairly easy to coordinate. Much of the time you end up with one person doing most of the work, two people who add some comments/graphics/whatever and two people who do virtually nothing. It's an inefficient approach, but it's easier than trying to get everyone to work up to their potential. But once you scale that up to thousands and thousands of people, this sort of casual approach to managing the task flow fails utterly. You need people whose entire job is thinking about how the complex dynamic system functions - and ensuring it continues to do so."
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7jsuju | Why isn't AC electricity converted to DC before it reaches the power outlets? | Why is it that every device has to convert AC from the wall into DC, instead of converting AC to DC when it comes into the building and having the wall outlets run DC? | Technology | explainlikeimfive | {
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"First of all, there are appliances that run better on AC power, so why waste effort on converting it? Items that involve motors or resistive heating either want AC power or are perfectly fine with it. Second of all, you don't know the voltage of all possible DC appliances. If you're going to need to transform your voltage anyway, you might as well just leave the power as DC. In theory, you can speculate about some future where all the power sockets in our homes are 5V USB-Q or something, capable of charging your cellphone or running your washing machine with equal facility. But we're not there yet.",
"Different devices have different power needs, and AC is much simpler to change level than DC.",
"Every device? Only the most modern electronic devices use low-power DC. Historically—until a decade ago—most devices we plugged in used 120-volt AC to run motors or heat filaments.",
"It creates a few issues. What voltage would you run at? If devices have to do massive amounts of DC-DC conversion anyway, what point is there in a DC wall outlet? But at the same time, if you choose a low voltage, high-powered devices would require possibly hundreds of amps, which makes wiring very expensive.",
"My phone needs 5 volts DC to charge, my laptop needs 16.5 V, my little desk lamp uses 12 V, and that's just stuff that happens to be in my office right now. DC voltages are hard to convert from one voltage to another. If we did it your way, we'd need a different power outlet for every voltage."
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7jwiv6 | Why does audio recorded from speakers sound horrible, while audio recorded naturally (IRL) sound so much fuller and better? | Technology | explainlikeimfive | {
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"A similar question was asked in r/NoStupidQuestions with a great [answer]( URL_0 ) by u/Afflo. For the lazy: > If you record a speaker with someone's voice, it will sound bad. I'm assuming you aren't using studio grade speakers and studio grade microphones. > A speaker will have a frequency response that doesn't quite match reality. > A microphone (especially a cheap one) will have a frequency response that doesn't quite match reality. > When you play something recorded from the speaker, you are essentially layering three levels of degradation - the original speaker output, microphone input, and final speaker output... And this doesn't even consider the acoustics of the room. > If you take a picture of a picture of a picture of a pictures, you'll do the same - layer after layer of color and detail loss from printing and capture. Even the classic \"mirror facing a mirror\" will illustrate this - as you look through the infinite hall of mirrors, the reflection fades and distorts as you combine the imperfections over and over. > If you have a high quality studio and fine tuned equipment, the loss of fidelity can be managed to some extent. If that's the case, you're also probably an experienced audio engineer!"
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7jwnw8 | Can someone explain the difference between MRI, fMRI, PET, and EEG scans? | A small description of each would be fine. I know they all examine the brain in some way, but I'm confused as to what each one does specifically. Need the info for a final exam in psych tomorrow. We are given scenarios and we must choose which type of test would be best. | Technology | explainlikeimfive | {
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"MRI: Allows us to see brain tissue, nerves, bone, fluid etc. No radiation. If some dye is used, it can highlight certain things like blood vessels or certain diseases better. MRIs take longer than CT scans to perform and are better at looking at tissue generally while CTs are better at looking for blood. fMRI: f is for functional. It is primarily used for measuring brain activity by looking at which part of the brain blood is flowing to. Mostly used for research rather than clinical medicine. PET: Some radioactive material (usually a sugar) is injected into your bloodstream, when you are scanned, the parts where it's really bright are where this material has accumulated. Often used to look for cancer cos tumours need sugar to grow. EEG: Think of it as an ECG/EKG for your brain. When nerves fire/work, it gives off a small amount of electrical activity - this has a predictable pattern. Electrodes are placed at several points around your head and the electrical activity is picked by the machine and translated on to a strip of paper. We use EEGs to diagnose epilepsy. Technicians will often attempt to induce a fit using various equipment and methods and hope that we capture it on the machine.",
"fMRI and PET scans can be used to watch active processes in the body. You can watch blood flow and metabolic processes as they happen and change. PET scanners are mostly used for cancer imaging while fMRI scanners are mostly used for brain research, watching what parts of the brain activate via different stimulus. MRI scans are used for fixed high resolution images of soft tissue, the kind of tissue that doesn’t show up especially well on X-rays/CT scans. You’d use an MRI to accurately diagnose a brain stroke or soft tissue injury to a knee joint. EEG are direct measurements of electrical activity of the brain. You can use these to diagnose things like epilepsy."
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7jysso | how was Russia able to redirect all cloud traffic through their country from multiple sources like Apple, Microsoft... Etc. Wouldn't they have to compromise all the individual systems (like apple) to do this? What are the broader implications of this? | I have so many questions that I don't even know where to start asking or if I'm even asking the most important questions. | Technology | explainlikeimfive | {
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"The way your computer knows where to send your network packages is through something called a \"routing table\", which is basically a mapping of networks your computer knows about, and the corresponding physical ports on your computer. On your home computer this usually has only one entry: \"send all packages through my wifi card\". That will and up at your home router, which has a slightly more complicated routing table with two entries: * send all packages addressed to the local network out through the wifi (this is how you access other computers in your house) * send all other packages out through the internet connection to the ISP At the ISP the package that you send to Apple, is processed by their router. That router is much larger and there might be very many of them, so their routing table is much much larger. The ISP might have a youtube server right in their own datacenter to help speed up videos, so there is an entry in the routing table about that, but for example to reach Apple, it might send it to a different ISP, who knows yet another ISP who knows where the Apple server is located. Because this is very complex, these tables aren't configured manually, but they use something called the [\"Border gateway Protocol\"]( URL_0 ). That basically works by Apple sending out a message to all the routers it, in turn, knows about, saying: > Hey guys! I am Apple and please send all network packages that should go to Apple through this connection here: ::ROUTING INFORMATION:: Turns out, this message is not authenticated in any way, so anyone who is part of that network of routers can send such a message with false information. It's amazing how fragile some of these things are.",
"The Internet is a series of tubes. The Russians tricked the tube conductors to take alternate paths to their destinations. The tube conductors will take orders from anyone without verifying their authenticity.",
"They way traffic is routed is quite simple: you never really know how to reach someone but you always know who knows how to reach someone. So your computer ask your router Your router ask your isp Your isp ask someone else ... and this can go one a few times before your packet reach its destination. The thing is: the way routers know where to send the information is through word of mouth. If someone says he knows how to reach someone else, you trust him no matter what. Even better if they say they ARE YouTube.",
"They used a protocol that tells routers how to get from network A to network B to tell them to go through the Russian network. The network operators generally don't filter this kind of request because it's mostly used for legitimate purposes like when someone's network crashed or is overloaded. See [Wikipedia]( URL_1 ) if you want to read up about how it works. [This site]( URL_0 ) has a fairly easy to understand explanation.",
"El15: The internet is a series of interconnected networks. Each network trusts all the others to behave and listens when they broadcast instructions. These instructions tell the rest of the networks the directions to get to their destinations. So any network operator that is connected to the internet and has addresses from their regional ip address authority and has the right equipment can broadcast these instructions that all the other networks implement once heard. The broad implications are complicated. So far as i know incidents like these have been accidents. A network engineer made a typo or equipment went shit. but there's a good chance nation states use the method to intercept traffic and information on a selective basis. Say you are in new Zealand and one of the powerful nation states has an interest in your signals. You have collection nodes scattered across the globe tapped into fibre at various important points but maybe not everywhere. If You are a nation state actor you may have compromised access to an is in Brazil where you issue routing instructions telling the whole internet to change the path for a group of ip addresses. Then this route is collected and fed into your sigint system.",
"The first thing you have to understand is that a significant amount of what was claimed is total propaganda and simply is not true. I say this both as an American who is fed up with our media and politics as well as an I.T. professional with over 20 years experience who works in the US aerospace industry. When you say “all cloud traffic” you’re basically saying “all internet traffic” sent/received from these companies. It’s simply not the case. Even if it were, the state of IT security at these places is going to include encryption, RSA tokens - so even if someone could get the traffic it’s not going to be a trivial matter to decrypt it or have it in a useful form.",
"What are you even talking about? What did the Russians do?",
"Imagine traffic is like mail that gets delivered to your house. Any local mail in your town stays in your town and is delivered based on a set of street addresses right? What about when your mail goes further to other post offices... the mail has a zip code and then it's delivered to the post office at that zip code and distributed. What if someone could just tell the post office \" I am zip code 90210, any mail for that zip code should come to me\". That's basically how border gateway protocol works at the business level. A person sends a bgp advertisement saying, any traffic for Apple should go here\", and the internet routers believe it. In our mail scenario, this entity in Russia has said \" I'm zip code 90210\" packages started coming to Russia instead of 90210 Beverly hills , then Russia opens the mail, reads it, packages it back up and sends it to the real destination. Believe it or not, internet routers are that trusting in certain circumstances. Now the person in Beverly hills 90210 receives the letter but it originally had a wax seal (think of this as ssl encryption) on it that is now broken. Senders and receivers of this mail will know it didn't come from a reputable source, but governments have ways of faking the seal that normal people do not (hijacked certificates or trusted certificates in a computer certificate store) this could mean packages can be sent back and forth and people assume they aren't tampered with, when in fact they are. Another thing to take into consideration is this.. If the package isn't delivered, the post office will instantly fix the issue.. meaning this is tough to keep going for any significant amount of time",
"[China did this to 15 % of the world's Internet traffic in 2010 for 18 min. Russia used the same method.]( URL_0 )",
"The article I read said the data was routed to Russia, this doesn't mean the Russian's did it. Like the old saying is around here \"you don't shit on your own doorstep\".",
"The system that allows your computer to translate a website address (ex: \" URL_0 \") into an IP address that it can actually connect to is basically set up like Wikipedia. Anybody can suggest edits to it, but generally speaking, any outlying crazy edits will get quickly overwritten by the majority. These tables are replicated by word of mouth between computers, but there is very little actual verification. The system basically runs on the premise that the majority of computers, in aggregate, isn't wrong. And most of the time, this is a safe assumption. Similar to a Wikipedia edit-bomb campaign though, it is possible for a really dedicated actor to overwhelm the system by telling a critical mass of computers to update their routing tables to point to a false location. This can be done strategically at the choke-points of interconnected networks, like those between countries, where a lot of this \"word of mouth\" information comes through. It's still really hard to pull off for long -- the equivalent of editing the Wikipedia page for \"The United States\" to point to \"Bangladesh\" and getting it to stick, but it can be done for short periods of time.",
"First, there are AS's. Second, there is BGP protocol. AS's decide their routing tables based on a number of factors, such as reachbility, hop count, etc. Reachability and hop count are provided via BGP. In essence, any AS can broadcast to all other AS that they can reach certain address. This is what the Russians did. Yes, the system is not secure, but it was never designed to be.",
"I'm late but I have a simple answer to share. Imagine you need to go somewhere and you're not sure how to get there. You'd probably pull up Google Maps and follow the directions it gives. The Internet is the same way. Data is delivered from one place to another by following mapping directions from routing protocols. Now, imagine Google Maps freaked out one day, and everyone that tried to use it was given directions that sent them all through one intersection in one town. Tons of people would find their way through that place. This is essentially what happened in the Internet. The routing protocols freaked out because bad data was injected into it, which screwed up the directions given for data to be delivered. As a result, a ton of traffic was sent through one system in Russia.",
"The internet is not one big interconnected system like a spiderweb. It’s a collection of tens of thousands of separate autonomous systems. Each AS is like a separate country. They each have peering agreements, like treaties, to dictate how traffic flows between their system. For example, Comcast’s Pennsylvania AS might have an agreement to share traffic freely over a certain link with Verizon FiOs, or Harvard’s network, or even Vodafone. There are tens of thousands of these systems. And you don’t automatically know where a certain IP address is over the whole internet. That’s why each AS advertised ip prefixes. That’s how you know which actual web server has an up address you’re trying to find. It works over a system called BGP. And it tries to find the best route from you to your destination. But BGP is surprisingly easy to fool. It trusts advertisements from anyone. If you’re in New York trying to reach a Russian Bitcoin site, that would normally be a long series of hops. But an evil rogue AS in Pennsylvania with a malicious server could advertise the same up address as the bitcoin site. Since it’s a shorter path, and since there’s no real security with BGP, your computer will go to the server in Pennsylvania instead. So basically, it’s like giving wrong directions to a tourist in a world where everyone assumes people to give correct directions. It’s surprisingly easy."
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7jyysy | Why do programs sometimes refuse to close? | You know, when the program's window greys out and it gives you an error message, but won't close even through forcing it with Task Manager or alt-f4. | Technology | explainlikeimfive | {
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"It could be caused by a blocked process waiting to acquire a 'resource' held by another process. Until this resource is acquired, the program wont be executing a terminate process. Same as deadlock situation.",
"Operating system has varying ways to try killing a process. Most of them can be \"captured\" by the program itself, so if operating system sends a \"shut down\" signal, program can intercept it and try to close it down by itself, allowing it to save data and otherwise do cleanup on itself so it's less of a crash and more like program closing. Which is a problem when program somewhy gets stuck in some logical loop that prevents it from even processing that order it intercepted. So it's in some logical loop, maybe counting to one trillion, or maybe waiting for some event that never happens, and the intercepted command just waits to be processed after. And it never will. In task manager you have some special option called \"kill the process\", which cannot be intercepted by the program itself. It simpy frees the memory program was using and removes the program from the list of running programs. Anything you were doing is gone, and any data the program was handling may be corrupted as a result."
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7jz7pr | What happens to information and media (texts,apps,videos etc...)on your phone when they are scrolled out of sight? | Technology | explainlikeimfive | {
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"They are kept in the device's RAM as you use the app, so that when you scroll back up, they are instantly available. Some apps may run out of RAM or otherwise optimize to save it, so the data will be erased from the RAM and lost, thus when you scroll back up, then it must re-load the data from the internet."
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7k2kxh | How do programmers code chess-playing computers to make mistakes? | Technology | explainlikeimfive | {
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"You don't specifically code it to make mistakes. You code it so it doesn't pick the best move. Chess programs work by testing out a large number of moves into the future and assigning points generally based on how many pieces it is able to keep and how many pieces it is able to capture from the opponent. On \"Easy\" mode, the computer just won't look as many moves into the future, or won't pick the best possible moves out of all the possibilities it found.",
"Chess isn't a \"solved\" game; there's no known sure-fire path to victory. This means your chess machine can make mistakes because it's hard to tell what a mistake even is, even if it's playing it's best. It's not like naughts and crosses where you intentionally have to not play optimally if you don't want a 100% win rate. For an actual answer, a chess engine typically looks a certain number of turns into the future, computing all/the most likely options and deciding which one it will take. To limit a chess engine you can simply limit the number of turns ahead it can look. It's currently impossible to look through all possible moves to the end of a game, so this limit exists anyway and you just have to lower it. Another way to \"weaken\" a chess engine is to change the way it \"scores\" a move. I touched on this earlier when; there's no objective way to say one move is better than another for any two arbitrary moves. You might be able to say \"moving your queen in a place where a pawn can take it is an objectively bad move\", but it's a lot harder to come up with a way to compare any 2 given moves. A simple method would be to say that every piece is worth so many points (1 for pawn, 4 for bishop...) and see if any moves will make the opponent lose more points than you. This is a very simple one with obvious flaws. So you come up with the best way of evaluating a move that you can think of, and let your chess engine use that. For an easier setting, you make it use a worse way of evaluating moves. Lastly, you can have the engine work out the best 10 moves and then pick randomly from those, perhaps you weight it so that it's more likely to pick the best ones on \"hard\" and less likely on \"easy\".",
"Most typically they are simply told not to look far ahead. They can also be told to randomly pick from among the top few moves instead of the single highest-rated move.",
"The algorithm works by trying a selection of moves, and using rules to determine a score. It then chooses the highest scoring move. If you add a random number to each score, then the computer will still usually make the best move, but occasionally make the second or third best move. But will still have a bias towards the better moves."
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7k5ft5 | Communication Protocols. What are they, how do they work and why is there so many different ones? | Technology | explainlikeimfive | {
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"A \"protocol\" is just a set of rules for how to communicate. A good example of a protocol would be answering a phone before there was caller ID. * Phone rings. This is a signal to pick up the phone. * Callee picks up the phone and indicates that they are listening. (\"Hello?\") * Caller identifies themelves. (\"Hi, this is Alice.\") * Caller asks for the person they wish to talk to. (\"Is Bob there?\") * Callee attempts to find that person (\"This is Bob.\", \"Hold on, let me find him.\", \"He's not here right now.\") * If the intended recipient of the call can be found, the two parties continue the conversation. * If the intended recipient cannot be found, the callee takes a message for the intended recipient (\"Can I take a message for Bob?\") When computers send messages to each other across a network, they need a set of rules to follow similar to the ones above so that they can understand each other. If both computers follow the same set of rules, then they can successfully transfer information from on to the other. The reasons there are different protocols is because different circumstances require different kinds of communication. We do this as humans, too. Not everything can be done via text message. Sometimes it's easier to write an email, make a phone call, or just go talk to someone face to face. From a human perspective, each of these has a different \"protocol\" associated with it. When you send an email, you don't need the \"Hello, who is this\" exchange that a phone call might have. A phone call doesn't have paragraphs, the way an email does. Another reason there are many different protocols is because often one protocol doesn't solve the whole problem. Loading this web page requires the use of several protocols all working together. Off the top of my head some of the protocols likely used while transmitting this web page to you were Ethernet, IP, TCP, HTTPS, and TLS. Each of these solve part of the problem of communicating across a computer network. Ethernet allows one computer to talk directly to another computer over a wire connecting the two. The path from Reddit's servers to your computer goes through many such direct connections. IP (Internet Protocol) is how the message finds its way through those many hops along the way. Messages sent with IP are very small, and large web pages need to be broken up into multiple smaller messages, and then reassembled at the other end. TCP (Transmission Control Protocol) is how that happens, like if someone sent you a novel ten pages at a time, and you had to reassemble the pages into the full book. TCP can deliver any sort of message, but a protocol like HTTPS is a set of rules for the structure of that message. TLS is a protocol used to encrypt and decrypt the message at both ends. So, these all do different things and work together."
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7k5w9d | What's after 4k resolution, and when will we get there? | Technology | explainlikeimfive | {
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"8k resolution has been a thing for a long time. Its just not very popular.... why, well frankly, we're really not even at 4k yet in the general market. Very little video content is available in 4K. There's a lot of screens that do 4K, but minimal content. Instead of resolution, HDR is more likely to be the \"next big thing\" for video. 4K HDR is gonna be around a long time. Its really good and has a lot of benefits instead of bumping up to 8K.",
"First let's understand what 4k is. 720 is a resolution of 1280 x 720 for a total of 921,600 pixels. 1080 is a resolution of 1920 x 1080 for a total of 2,073,600 pixels. 4k is a resolution of 3840 x 2160 for a total of 8,294,400 pixels. 8k, the next step up, is 7680 x 4320 for a total of 33,177,600 pixels. You'll notice that the naming scheme changed from 1080 to 4k because companies thought using the bigger number was more impressive. What we know today as 4k should really be called 2k or 2160. As for quality, every time we double the horizontal number and go up a quality step we are actually quadrupling the number of pixels. If TV's don't get any larger more pixels will stop mattering as we already can't see individual pixels anymore at a normal viewing distance.",
"This depends on what you mean by \"when will we get there?\" for the common tech user, it may not advance quickly, as there isn't much demand for higher than 4k resolution. Panels with higher resolution are available if needed, although not in your average market. 4k is excellent, and impressive technology at that, but in many instances, even 1080p is adequate. But there are already 5k panels. It seems to me that resolution will keep getting better, as we demand larger displays with higher pixel density.",
"At the moment the acquisition and distribution of UHD Phase 1 and Phase 2 (4K and 8K for TV) is not widely developed for many reasons. The bandwidth requirements for an UHD are very large and the technology is not really there for the distribution to the home. Whilst UHD Phase 2 (8K) will be the next resolution jump we are still a long way off from delisting it. Tests are being done at the up coming winter games and football World Cup. The next development for home entertainment will be HDR. There are different types of HDR. HLG HDR is being developed by the BBC and is about to be tested very shortly in the UK. The is a type of HDR that’s is compatible with screens with a standard dynamic range. TV’s will start being developed with different HDR standards. Not all standards are equal with some allowing content to be displayed at higher nit rates and dit depths which is what you want as a consumer for a better colour and brightness range. The one standard being developed to look out for is ‘Dolby Vision’. This standard incorporates dynamic metadata. This allows the tv to set the dynamic range on a frame by frame basis rather than an overall range for the entire programme. Dolby Vision also allows a higher theoretical nit rate of 10,000, however only 4000 can be achieved at the moment. This higher nit rate will allows brights to be brighter and darks to be darker. Look out for Dolby Vision in upcoming TV’s",
"6k then 8k? Honestly we have hit diminishing returns when it comes to resolution. Next is HDR and better picture/color like OLED. Then VR?",
"What is the relatable viewing resolution of the human eye? Will these Ks get to a point where it is simply imperceptible to the eye at normal distances?",
"There's literally no reason at all to go above 4k resolution. For most viewers at normal viewing distances, the difference between 1080 and 4k is difficult to resolve. The difference between 4k and 8k would be impossible to resolve. We would get better results visually from an expanded color gamut, increased color accuracy, and better contrast than we ever will from increasing the resolution beyond 4k.",
"We are limited by bandwidth and processing power. Broadcasting/transmitting 4k is trouble enough that it will be a while before we go higher. Things tend to stay in powers of two when it comes to technology so the next logical step will be 8k although we are starting to see more work put into actual quality over quantity which is why HDR is being pushed along with 4k. As most people don't want a TV over 65\" the quality improvement over 4k is extremely small where deeper colours does far more to improve the image quality and allows for the studio/director to produce a truer to their vision final product."
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7k6b7j | What is IBM compatible PC? | How does it differ from modern PCs? Does Apple Mac' belong to this category? | Technology | explainlikeimfive | {
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"The IBM PC is a literal name of the device that was developed and released by IBM in 1981. [link]( URL_0 ) It was a low-cost computer for a personal use built with generic hardware components, so the market for such devices was quite huge. Because of that a lot of companies started to release their own clones of IBM PC based on the same architecture and similar components. Such devices were often referred as IBM PC clones, or IBM PC compatible. Oh, and it's not \"IBM compatible PC\" since there was and is a lot of different IBM computers. The correct term is \"IBM PC compatible\", which means it's similar to IBM PC device.",
"Back in the day, and by that I mean the 80s, there were a few different brands of PCs that had their own OSes and architectures. Apple was one, IBM was another. IBM compatible PCs were computers that used the same architecture as IBM, and could therefor run the same software. Modern PCs are descendants of the IBM and IBM compatible PCs, but IBM doesn't really do much in the PC market anymore so the term isn't used. Apple and later Macs were not IBM compatible, although now they use Intel chips anyway.",
"In the good old days computers were giant things that you had sitting in a room in big companies and connected what were little more than mechanical typewriters to it in distant places. They were not for everyone. Then computer became smaller and smaller and microcomputers were suddenly a thing. Still rather expensive but suddenly small enough to fit on a person's desk. Some clever people came up with the idea that you could not just use them for work but also at home to do things. And the idea of a home-computer was created. So there was a large variety of computers that were supposed to be small and affordable and used in businesses and in the homes of people who were rich enough to afford them. They were all different and mostly incompatible with each other. Then IBM came into the picture. Or rather some clever engineers at IBM. The company had been (and still is) in the business of selling business large mainframe computers. They wanted to get in on the whole small computers business, but not enough to spend serious time developing stuff for it. So the engineers who were assigned to the project simply put together a small computer from of the shelf parts. At that time IBM usually still made all the hardware themselves from disk drives to keyboards, but the company did not consider this minor project worth the hassle of developing special hardware for it, so the engineers took what everyone could get and put it together for a relatively small, cheap and powerful computer. Thus the IBM personal computer was born in 1981. It was not particularly better than most of the competition but it had the IBM name attached to it and in those days people still believed the saying that \"nobody ever got fired for buying IBM\". They got a small company called Microsoft to license some software called DOS for it and sold the whole thing to customers. Now as I said above IBM normally was in the business of making the whole computer themselves. The build their own computer chips and their own software and their own everything. But for this little project, because of the lack of a proper budget they went with parts that they didn't own the sole rights to. This meant that somebody else could come along and build a computer from the same sort of parts and put the same software on it and have it work the same. Nowadays we sort of expect that a computer bought from HP or DELL or Lenovo will work the same and that you don't have to buy different programs depending on the manufacturer of the computer (except when it comes to smartphones). Back then it was a completely new concept, you could buy a cheap clone of the IBM-PC and run software on it that was meant to run on the IBM-PC. Imagine that! getting something that works as well as an IBM computer without having to pay IBM prices for it! The manufacturers of these computers put labels on them to let the buyers know that they would work just like IBM-PCs and the makers of software made it clear that their software would run on computer that was built to be compatible with the IBM-PC. This proved to be a huge thing because suddenly all these different companies involved could target their products at a single type of computer that was produced by a large number of different manufacturers. And that was not all the parts for these computers could be made by a number of different vendors too. Today we only have Intel and AMD left, but in the early days there were a larger number of chip manufacturers who made chips that worked the same and which would fit in the same motherboards. You also had all sorts of different business making other parts like video-cards and sound-cards or memory chips or whatever you had. Even the software could be switched out to a degree. Towards the end there were a number of OS that worked just like MS-DOS without being from Microsoft. Everything was standardized and everyone could play. This meant that IBM-PCs with their modular nature that everyone could make parts for and that could be upgraded came to dominate the Personal computer market. The Domination was so complete that after a certain point people stopped using the name \"IBM compatible\" because that was the default and only type of PC that there was as far as most consumers were concerned. You Commodore and Amiga home computers just could not keep up with the market dominance of the IBM-compatible PC. Apple was for a long time the only survivor with any sort of market share which was not an IBM-PC . (This despite the fact that Apple's computer were actually called PCs and that their architecture was actually the PowerPC chips made by IBM) To naming convention shifted to something like x86 to mean everything based on the original IBM-PC after the ending of name of the intel chip used in them. At some point people realized that the architecture was usefull enough to build more than just PCs out of it and they started building servers out of IBM-PCs. This further helped to kill of the remains of much of the old type of mainframe computers. At some point about a bit over a decade ago IBM realized they were no longer making much money of building and selling their PCs. they still sold a lot of them but the competition that came from everyone being able to build basically the same thing mean there was not much profit in it. IBM sold their PC business to the Chinese company Lenovo. Several year later they also sold the division that made servers based on PCs to Lenovo. So IBM despite inventing the format today no longer actually makes IBM compatible PCs. But everyone else does. All the normal PCs today are IBM-compatible ones. Even apple switched to the IBM PC compatible format a decade ago. But just as the victory of the x86 architecture seemed complete smaller computers in smartphones using ARM architecture started becoming popular. They appear in phones and even in some tablets and cheap laptops. they also appear in all sorts of small devices that have computers in them from TV-sticks to smart home controller. So while the IBM-PC has won over almost all its old competition, just as it was close to victory IBM stopped making them and a new competitor appeared that is rapidly gaining on it.",
"In the 1980s, there were several incompatible personal computers on the market, IBM, Apple, Commodore, TRS, Timex-Sinclair, Atari, and more. IBM used unpatented off the shelf parts and licensed an existing OS rather than make their own. That meant other companies could make computers that were compatible with software written for IBM PCs, and many less expensive IBM \"clones\" were on the market. This, in part, is what allowed the IBM style machines to win the PC wars. True IBM PC cost a hefty premium and had little to offer over the cheaper clones. Eventually, they surpassed IBM and were more properly Microsoft OS and Intel CPU compatible, but the term IBM compatible stuck. These days they are more commonly just referred to as PCs while other computers are referred to by brand name."
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7k733c | how can a software update to Qi increase charging speeds? | Technology | explainlikeimfive | {
"a_id": [
"drc2ra3",
"drcmeib"
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"text": [
"With modern batteries the charger isn't just apply power and it charges, it actually has circuits that control exactly how fast it charges so the battery isn't damaged (charging speed needs to be slowed down when they get near full). in your example Qi probably provides more power than the battery can use, and someone probably figured out that they actually can charge the battery faster than they thought without damaging it, so a software update can change the maximum charge rate to get it to charge faster.",
"A modern device's charging speed isn't limited by how much electricity can flow through the cable, it's limited by software to a safe rate of charging. Your phone tells the cable how much it can handle and the cable delivers. Because 'unsafe' in this instance can mean exploding Samsung phones they tend to program a lower charging rate than the theoretical maximum. As time passes they can test the devices more thoroughly and say \"this phone can handle a higher charging rate safely\". Then it's just a matter of updating the software on your phone to accept more electricity."
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7k9qv2 | How to water powered flashlights work? | Last night at my company Christmas party a few of our technicians received a gift called a Hydra Light. Basically the concept behind it is you remove the “power cell” from where batteries would typically be on a normal flashlight. Dip it in some water, and put power cell back in and boom it turns on. How is this possible? Where/how is the power actually generated? | Technology | explainlikeimfive | {
"a_id": [
"drcnt9q",
"drcr8vd"
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"text": [
"It’s like a potato battery. The gadget contains pieces of dissimilar metal, perhaps zinc and copper. Water acts as the electrolyte. Eventually the metal will corrode away and the light will cease to function.",
"It's a [salt water battery]( URL_0 ), a type of [sodium-ion battery]( URL_1 ). I'm not sure I can explain the chemistry in detail in layman's terms (or at all - I only understand the basics), but in short, it works like a lithium-ion battery in that electricity is generated by positively-charged sodium or lithium ions moving from the negative terminal (anode) to the positive terminal (cathode) through a solvent called an electrolyte. In a salt water battery, the water acts as the electrolyte, and a source of ions from the dissolved salt. This type of battery appears to wear out quickly compared to lithium-ion batteries that are recharged by applying electrical current to move the ions back where they started instead of replacing chemicals with fresh ones."
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7kacqp | Why do consoles (PS4 etc) require you to download the game as well as having it on disc? It seems like a waste of drive space, and also seems to make it indifferent to just buying the digital copy. | Technology | explainlikeimfive | {
"a_id": [
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"As games get insanely complex, the rate in which a game can read data off a disk, even a blu-ray disk, is just too slow. Loading a huge level off the harddrive may take 10 seconds, where that same load with the speed off a blu-ray alone would take a minute... which becomes impractical. It was actually game designers who forced Sony (and Microsoft's) hands. (A blu-ray can read 27mb/s, a harddrive can read 300mb/s) (note: My numbers may not be perfect here, but it's in that ball-park)"
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7kc9pf | How do printer cartridges work? | I've always wondered how the ink gets out of the cartridge and makes it onto paper with such detail. How does the printer create such fine details, such as small letters on an essay, onto paper so fast? And how do the colors mix to print out a photo? | Technology | explainlikeimfive | {
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"> I've always wondered how the ink gets out of the cartridge and makes it onto paper with such detail. I'm going to assume you are talking about an inkjet printer cartridge. That type of printer uses electrical charge to propel tiny droplets of ink out the nozzle and onto the paper. By carefully modulating the charge applied to a large number of tiny nozzles an image can be built up from the combination of those tiny droplets of ink."
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7kdby2 | Why does a li-ion/lipo battery explode when shorted out? | Explode is probably the worst case scenario; catch fire or even just puff up and smoke. Why do these rechargeable batteries react so violently when the old alkaline (disposable) batteries didn't? | Technology | explainlikeimfive | {
"a_id": [
"drdfgf3",
"drdgewh"
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"text": [
"The lithium atoms can crystallise and form a chain, that chain can short circuit the poles and it is this short circuit which can cause a fire. - URL_0",
"They have much higher energy density (meaning there is more energy stored in the same mass/size) than other batteries. All that energy has to go somewhere when a battery is shorted - it just turns into heat. Then the heat damages the mechanical structure of battery by burning off the layers of protective materials and exposes the chemicals inside which can now continue burning even after the electrical energy is exhausted. This is one of the reasons that electric vehicles will not get much better than they are now. The energy stored in batteries is very dangerous because it is easily released when shorted. Petrol, on the other hand, will not explode or burn unless mixed with oxygen. Lots and lots of oxygen. Therefore, it's much safer. We think of petrol as dangerous and batteries as safe but that's only because petrol energy density is much higher than batteries and we usually deal with much larger quantities of it. For batteries to be as effective in cars they need to have similar energy densities and similar size (actually, more size, because they can't use the oxygen from the air in the reaction) which pretty much turns them into bombs ready to explode and burn when shorted. And you can't just douse the flames because they don't need oxygen to keep going - all the usual firefighting techniques are less effective and you treat it as metal fire which requires specialist equipment to deal with."
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7kdk3s | Why the hell do phones have to have a "minimum charge" before they turn on, can't they just draw power directly from the source? | Technology | explainlikeimfive | {
"a_id": [
"drdge9h",
"drdhk3p"
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"text": [
"Drawing power from the source would require extra circuitry that's not used 99.9% of the time. And the phone has literally no more space for it.",
"Laptops have more complex power supplies that allow them to run either from the battery or external power, and to switch automatically. Phones are smaller, and space within the phone is extremely valuable. So phone makers use simpler power supplies, which are smaller. The phone ONLY runs off the battery. Plugging the phone into external power ONLY recharges the battery. The phone will not start until the battery reaches a certain minimum level."
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7kfkgn | How do polaroid pictures work? | How do the pictures just slowly come in there etc? | Technology | explainlikeimfive | {
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"dregvi1",
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"text": [
"Freakin' magic, that's how! In a nutshell, a polaroid is a little envelope that contains all the chemicals needed to develop and fix the picture. Light hits chemicals that are sensitive to light, which react with reagents in a different layer that cause dyes to migrate into the first layer and become visible. Developing a photograph takes time (the chemical reactions aren't instantaneous), and the first process to do instant color prints didn't work very well. The solution was to add another layer of chemicals that opacify soon after the exposure to light. This makes it dark inside the layers, and allows the time necessary for the developing and fixing process to happen without being exposed to more light. That opacifier breaks down and becomes clear after a period of time. That's what you're actually seeing when the polaroid comes out grey and image slowly shows up.",
"Many of the other posters have covered the developing process well, but I would like to add one thing. The white section down at the bottom contains many of the chemicals in a little pouch. When the photo is taken and comes out of the camera, it passes through rollers which pop this pouch and press the chemicals along the picture. The chemicals are still contained within internal layers so they don't get everywhere, though.",
"/u/bazmonkey covered it well, but two things I will add: Polaroid photos only need time to develop. \"Shake it like a Polaroid picture\" was something of a nervous tick we developed as a society. Shaking it did not help the photo develop at all. Another thing; if you use something with a point to draw on the photo as it's developing (a screw driver, a nail, etc) you can get a pretty crazy effect.",
"It's already been covered pretty well, but for those who are wondering how its possible, it works basically the same way as regular film works, just in one package. Here is a very ELI5 version: 1. There are chemicals in the paper that are light sensitive, such as silver. Imagine it like a sun burn, you can place a stencil on your body, then expose it to light and you will have a darker skin color inside the stencil. When silver is exposed to light it gets darker, this is why we have a negative when we take a film photo. The brighter the light, the darker the silver becomes, so its giving the opposite effect of what we see with our eyes, so it needs to be reversed into a positive. 2. Even in polaroids, the exposed image starts as a negative, but the chemicals in the developer bleach out the negative and you are left with a positive. 3. The white tab you see at the bottom contains the developer, when the polaroid is ejected, the developer is squeezed out over the exposed image, which stops anymore exposure and also starts to develop the image. After the image is developed and stopped, the negative gets bleached out after it leaves its imprint as a positive. BONUS: When dealing with chemicals, temperature has an effect on developing times and the effect of the development. If you have the chance, put your polaroid/instax in the freezer and then go outside and take a picture. Then leave it out in the sun and take the same picture. There will be a noticeable difference, such as different color-casts or exposures.",
"Here is how the old 600 film used to work, [Each instant photo contained chemical pouches at one end]( URL_0 ) I remember as a kid when the photo was taken my grandfather would put them face down in a small cardboard box that he carried the camera in to help keep them away from light as they developed. Also wiki has a great right up about the [instant film]( URL_1 )",
"Anyone here know how the new Polaroids hold up against the impossible ones?",
"Not a photographer or an engineer but I read about the process a few years ago. There are two chemical pouches on the photo “slide”. One is a mixture of the standard chemicals used to develop photos. The other is a chemical that is opaque and acts as its own dark room. The latter is design to protect the former obviously but it’s only good for a certain amount of time. Once it’s taken all the light it can, it starts to fade but by this time, the developing process is done and your photo become visible as the darkroom fades.",
"Each photo is a little package that has a silver coated pice of film, and a bunch of other chemicals that react with the silver and the film. One of them is an acid, one of them \"fixes\" the image (it makes it not smearable), chemistry stuff. When the picture is taken the negative (the film) is exposed to light coming through the lens and it makes an \"imprint\" in the silver coating on the negative. Then rollers squish the other chemicals onto the negative, completing what a photographer would do in a darkroom right there in the park. You'll note the opaque black back on polaroid pictures and the peel off backing. So then you wait a few minutes for the exposure (chemical stuff) to happen then peel away the excess chemicals and voila, you have a photo of your dog! You can under expose, (its all white!) or over expose (black box) your pictures if you peel them too early or too late."
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7kg3zf | Why did Video Games only work on Channel 3? | Technology | explainlikeimfive | {
"a_id": [
"dre17hq",
"dre4w4t"
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"text": [
"The video game system (and other external devices like a vcr) connected to the TV through the coaxial cable jack. At the time it was common for the TV to not have other inputs like A/V etc. So, the connector would make the signal come out in a way to be tuned on the TV, matching the same signal it would be looking for in channel 3. This process. is known as modulation.",
"**tl;dr:** TV's didn't have 'inputs' on them for the first 30 or so years they existed so they only way to get a signal in from an external source was to hack the antenna to replace content of a particular channel and make sure the TV was tuned to that channel. Make it a low channel number for backward compatibility, allow two channels for technical reasons. The rest of this post is a rough outline of the development of television inputs. Might be an interesting read if you want to know how TV was in the early 80s. Back in the day, televisions received video only over the air so you had to connect an antenna. There were no VCR's or DVD players or even cable boxes. You had ~13 channels to select from using a physical dial on the front of the TV. So, back in the day, someone devised a way where you could connect a device to the antenna connectors on the TV and watch premium channels. This was cable. The box acted like a pass-through and you'd connect your tv antenna to the back of the cable box instead. There's also be a CATV cable connected to the back of the cable box containing the cable signal from the provider. Cable offered a lot more channels than what your 13 position dial on the TV did so what they did is make it so you had to tune your tv to a particular channel to see the cable tv. What the cable box was doing was basically replacing whatever was coming in on the antenna for this particular channel with whatever cable content you were trying to watch. At some point, cable companies eventually standardized on channels 2 and 3 (using a switch on the cable box) because it's easier to send a clear signal on a channel which isn't used in your area than one that is. Also, due to technical issues, you generally wouldn't have content on BOTH channels 2 and 3 in any given area. Also, low channel numbers pretty much guarantee that old TV's from the 60's which only had something like 5 channels would still be able to connect to cable. (In the 80s, it wasn't uncommon to be using a black and white television from the 60s. Shit was built to last.) So JVC and Sony come out with video cassette systems. This is all fine and dandy, but how do you connect it to a tv which has only power and antenna connections? The same way as cable. There's a signal in connection which connects to your antenna or the signal out from a cable box. There's a signal out which goes to the TV's antenna connection. Now, it this point, I should mention something about TV signals. Basically, each tv channel is a few sound signals and an NTSC signal (or PAL if you live in some backwater European country) then the whole thing is modulated with an FM carrier signal. If you keep the FM carrier frequencies separated by a few megaherts, you can send multiple channels (multiple video and audio streams) through a single wire. VCR's and (less so cable boxes originally) needed to only send one signal. All this channel 2/3 bs was because the only way to get a video signal into the TV was to modulate the whole signal with an FM carrier just so the TV can demodulate it. Way complicated for just trying to get one channel into a tv. RCA started building TV's where you could send it an unmodulated NTSC video stream. This is literally the video stream the comes in over the air, but with the FM modulation... demodulated... and the sound stripped out (they used a couple additional connectors for sound). Just about every modern tv up until a few years ago had this: three RCA connectors colored red, white, and yellow. Most VCR's, all game systems, and most cable boxes and pretty much anything else that sent a signal to the TV could use the RCA system. Since you got a better picture than using the antenna connector, it was always recommended to use this if possible. To maintain backward compatibility, though, these devices would still contain all the electronics to modulate the signal and replace channel 2 or 3 on whatever input signal was coming in. Now... on game systems like the NES, you had an external device, the RF Switch, which had a signal in (from cable/antenna) and a signal out (to tv). There was also a connector which ran to the NES. When you turned on the NES, it would send the broadcast signal on either channel 2 or 3 to the RF switch. The RF switch would then inject the NES's signal into the TV's antenna. And now you're playing SMB3 or the Legend of Zelda, or whatever."
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7kgmug | How do waterless toilets work? How do they not smell constantly? | Technology | explainlikeimfive | {
"a_id": [
"dre5y7t",
"drejhq5"
],
"text": [
"They use a puck that reduces the smell when urine passes through it. Then the urine/cleaner combo go into the drain. The drain still uses a p-trap or a U-shaped bit of pipe that will hold liquid to prevent sewer gases from escaping.",
"The two main types of \"waterless\" toilets are composting toilets and electric incinerator type toilets. Incinerator type obviously need electricity and simply burn up the waste with odor handled by fans and venting. Composting type units store the waste in sealed containers and use similar types of venting. Then there are the vault outhouses in most forest service campgrounds which do smell constantly."
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7ki4fo | If cinemas now get movies as a Digital Copy how come they dont get copied and leaked online well before the DVD release date? | Technology | explainlikeimfive | {
"a_id": [
"drejgoy"
],
"text": [
"There are small watermarks in each copy that uniquely identifies it. If a theater were discovered to have leaked their copy, the movie studio would stop doing business with them, which would almost certainly cause the theater to go out of business. So theaters are *heavily* incentivized to be as protective as possible of the copies of movies that they have received."
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7kigo3 | How does a progressive web app(PWA) work? | I'm interested in the topic but I find it hard to understand some points of it. From research, I know that a PWA acts just like a native app but instead, it's on a website. So how does it actually work? What are the best uses of PWAs? | Technology | explainlikeimfive | {
"a_id": [
"drevqls"
],
"text": [
"From my understanding: It’s an application hosted on a web browser. Let’s say you open an application, like any other, it feels and looks like one. But on the back end it really opened up a web browser to host the software on. This way, the software is always up to date, bugs can be repaired quickly, etc."
],
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7kihr0 | How was mail delivered in the 18th century if there weren't exact addresses? | Technology | explainlikeimfive | {
"a_id": [
"dremnbe",
"drenj3s",
"drenjtm"
],
"text": [
"It would go to the local pub or other establishment that people went to often. Then people would just pick it up as they happened in.",
"It was a real mess is the best answer. Really, mail would just go from post-office to post-office and it would be up to individuals to come down and collect their mail. IF a post-office was not nearby, then the mail may go to a \"by the way\" (A business that was by the way of that person). A good article on this with a few snippets from it: URL_0 In practice, the post offices of these days did not generally deliver mail to households or businesses directly, but only from post office to post office. A 1796 report to the House gives some flavor of what a dog’s breakfast this system could be: “ALL THE PAPERS AND PACKAGES DELIVERED TO DISTANT CUSTOMERS AND TO BE LEFT AT DIFFERENT OFFICES AND PLACES, ARE PUT LOOSE INTO THE PORTMANTEAU WITH OTHERS, FOR SUBSCRIBERS LESS DISTANT, AND AS OFTEN AS THE MAIL IS OPENED THE NEWSPAPERS ARE THROWN TOGETHER OUT OF THE PORTMANTEAU IN ORDER TO FIND THE INDIVIDUAL PAPER AND PACKAGE TO BE LEFT AT SUCH OFFICE OR PLACE. AT SUCH TIMES THERE IS GOOD REASON TO SUPPOSE PAPERS AND SMALL PACKAGES ARE TAKEN AWAY BY PERSONS PRESENT AT THE OPENING OF THE PORTMANTEAU, TO WHOM THEY ARE NOT DIRECTED, BUT WITHOUT THE KNOWLEDGE OR PRIVITY OF THE POSTMASTERS OR CARRIERS OF THE MAIL.” On top of this, people could pay additional money to a business or an individual to hand deliver letters to you.",
"\"Mail\" - that is, a government postal service as we know it, with stamps and mail carriers who delivered mail to your home - did not exist until the 19th century. In the 18th century, you wrote a note and sent a servant or courier to take it across town, or you sent it along with a coachman to the nearest village where the recipient was. And generally it was the recipient who had to pay the delivery fee. Or you sent it along with a friend."
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7kil2p | How do cinemagraphs work? | I recently stumbled across r/cinemagraphs and can't stop watching those things, they're beautiful! But I can't wrap my head around how they work. [This]( URL_0 ) one over here for example is only one(!) second long but I still can't see a cut in there. How come this looks like it's moving forever? I tried googling it but only got some photoshop tutorials on how to make those things and since I have absolutely no clue how to use photoshop I didn't understand much. I also searched this subreddit and someone asked 2 years ago already but didn't get any answers. | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"They are .gifs someone takes a video or a segment of a video and they cut and play with it until it's seamless. The start of the .gif has to match the end as best the editor can perceive.",
"You start out by picking a piece of video that can be looped. There are several ways of going about this. The easiest way is to find a piece of footage that actually loops. For instance, a bicycle wheel spinning. The second way is finding a piece of footage that has a repetitious movement that doesn't exactly loop but is complex enough to hide the repetition in its complexity. Finally, you can make a rough loop and then go in to edit each and every frame of video by hand until it loops. This is more manageable than it sounds since these types of images usually are really short. Since most of these cinemagraphs take scenes out of movies, the last part is picking only one part out of a scene to loop. In your river example for instance, the people standing there would probably be moving. Even if they're not really doing anything, people don't stand perfectly still. So you take one frame you like, mask out the parts you want to be static and non-moving and use those as a mask on top of your repeating animation. Incidentally, it's a lot easier to do this in Adobe AfterEffects (video special effects software) than it is to do in photoshop. Although you might end up using both."
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7kis8o | How do music synthesizers work? | Technology | explainlikeimfive | {
"a_id": [
"drev7dq"
],
"text": [
"A synth has a number of different voices or oscillators (sound tone generators), each of which can produce waves of different shapes (sine wave, square wave, saw tooth, triangular wave, and so on). It can combine the waves to make complex sounds, and it can vary the way the sounds attack, decay, sustain, and release to make the sounds mimic existing instruments like pianos. URL_0"
],
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"text_urls": [
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|
7kld1s | What are jewels in analog watches for? | Technology | explainlikeimfive | {
"a_id": [
"drf7hcl"
],
"text": [
"Originally they were placed in [high wear points]( URL_0 ), because their very high hardness allowed them to replace metal components and wear less than the softer metal. Eventually, they succumbed to [Goodhart's law]( URL_2 ), and started being [added as a selling point]( URL_1 ) (the idea being more jewels indicated a more complex movement, but many jewels added later were simply added to increase the jewel count without increasing complexity)."
],
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"http://barrygoldberg.net/watchguide/jewels.htm",
"http://www.timezone.com/2002/11/04/83-jewels-too-many-part-1-92502/",
"https://en.wikipedia.org/wiki/Goodhart%27s_law"
]
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|
7kmst2 | Why are 3d models used for games, in a T-Pose when not in use or before an animation ? | For example, a lot of games uses this, but I never knew why [example]( URL_0 ) | Technology | explainlikeimfive | {
"a_id": [
"drfiwpz",
"drfo081"
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"text": [
"It's the best way to model or sculpt it. it's also more or less a standard, so you can easily take a skeleton from another model and place it on your working model. It allows for easier deformation modelling too. You can also model a character with their arms down, but then when you want to animate those arms upwards the deformation becomes a lot harder to get right.",
"Usually these days characters are modeled in [A pose]( URL_0 ) instead of T. The reason is that A pose is a much more natural position for the arms to be in. They are modeled in this pose for a couple reasons, it's easier to sculpt a character in this pose. It's also easy to rig the character in this pose."
],
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7knyu5 | - How digital clocks stay synchronized together | I was talking to my friend about computer clocks and I began to wonder how computers or phones stay synced together with their time. Are they connected to a server, or do they ever refresh for clock error? How does this work? | Technology | explainlikeimfive | {
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"The Internet is not just HTTP for websites. There is a separate protocol, NTP for [Network Time Protocol]( URL_0 ) (those Internet folks are sooo creative), which lets distributed computers agree on an accurate time. More accuracy means much more work, so most computers are not that precisely synchronized.",
"There is a protocol called Network Time Protocol which can be used to synchronize clocks. Most modern operating systems have it configured by default. In addition, anything with a GPS system in it can synchronize time based on GPS Data if it has access to at least 4 satellite signals at once. GPS is kind of special in that exactly 3 signals and already having the exact time will give you your exact position, but you can use a 4th signal instead of the time, and then get your time out of it.",
"For the United States the agreed upon timing standard is the US Naval Observatory or UTC(USNO). Each day as the GPS constellation is updated, tiny correction factors steer its timing signal towards UTC(USNO). Since the GPS signal is universally available, UTC(GPS) is used to steer most other methods of timing distribution through ground based receivers that are placed at precisely known locations. Since these receivers \"know\" where they are and \"think\" the GPS message is definitively accurate they can use it to steer their timing to match GPS then rebroadcast it to their customers. This allows NTP, NIST, the cell towers, NASAs ground based antennas, the Department of Commerce, and virtually every other networked clock on Earth to broadcast and utilize an accurate and synchronized time.",
"In addition to the methods mentioned, devices can maintain their current time when turned off through the use of a battery. This battery is usually a watch battery in computers, and functions to maintain some basic system setting as well as the time.",
"Standalone digital clocks don't stay synchronized at all. Computer clocks typically get their time over the internet. See, e.g., URL_0 As for cell phones, they also get their time over the network. The exact methodology for getting the time differs by network type, but it's the same basic idea--it gets the time from a central source. A GPS device (e.g., a GPS watch or a navigation display) receives the time from the GPS satellites, which are constantly broadcasting their current time."
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7ko4ax | What is an enterprise architect? | My dad can't explain his job to me. If it helps, he is also knowledgeable in SAP, which is another thing I don't understand. | Technology | explainlikeimfive | {
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"SAP is a company that makes a suite of tools, generally around accounting and human resources. Just like Microsoft Office has Word, Excel, PowerPoint etc. SAP has something to process people's paychecks, the company's bank accounts and generating expense reports. The architect's job is to connect all these different systems together. So when someone personally get's paid that goes through SAP's paycheck program, however it also sends a note to SAP's expense report program saying \"hey add $1,000 to the employee expense line\" and another to the bank saying \"hey withdraw $1,000 for John\". In many ways the enterprise architect is more analogous to a city plumber (which is also a civil engineer). They make all the connections between different systems, the same way a city plumber has to connect people's houses to the main sewer system and then route that to a repository.",
"his role is to make sure that all the big pieces of the corporate software picture fit together and work. whether it be the SAP system that tracks logistics, ties in with the accounting system, ties in with the CRM system like salesforce or any other internal and external business systems. additionally, his role might cover that any programmers working under him are following best practices and keeping up to date on technology and security concerns."
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7kz5iv | when the cable company says they will send a signal to your tv/modem, how does that works? | Technology | explainlikeimfive | {
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"The same way anything else gets to your modem/TV. Every device attached to their system has an address, just like your home address. They can just punch in that address and BLEEP BLOOP the info gets sent right to your device. The same way an email knows to go from my account to your account or a text knows to go from my phone to your phone.",
"With a cable network, everybody in the area receives everything, all of the time. Right now, your cable box is receiving all of the channels, even if you haven't paid for them - what it's not doing is allowing you to tune into them. When they send a signal (called a 'hit' in UK cable parlance, I'm not sure what other countries call it) that goes out to everyone in the area, and all the boxes and modems receive it - however, because that hit starts off with a bit of information that says \"I am for /u/xxgoozxx's modem, and that modem only\", all of the others will ignore it."
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7l4vkz | Why do drive sizes come in multiples of 4? | Like flash drives, hard drives, and SSDs. | Technology | explainlikeimfive | {
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"Actually, it's multiples of 2. Computers internally do everything in binary (base-2 counting) so things involving them tend to be in powers of 2."
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7l9gdm | How do push notifications arrive almost instantly after transactions occur? | If I'm buying something that triggers a push alert, sometimes it seems like I get the notification an instant after swiping my credit card. Considering we're told that streaming video or loading web pages can be slow because of the number of connections across the Internet, how does a transaction process fast enough from a credit card swiper to get to my phone so fast? | Technology | explainlikeimfive | {
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"Obviously different companies will use different technologies, but I'd bet a fair amount use [Firebase Cloud Messaging]( URL_0 ) (formally known as Google Cloud Messaging). At least on Android, there is a connection to the Firebase Cloud Messaging (FCM) that all apps on the device share. When a transaction occurs, your bank might send the FCM servers a request to display a notification on your phone. The FCM servers will then use that connection from their servers to your device to send a very small message to your phone. | Bank | --- > | FCM | --- > | Phone | This message is probably even smaller then this Reddit post. Just a couple bytes (1 byte = eight 0s and 1s). Since it is so small compared to a movie (which can be several gigabytes, 1 gb = 8000000000 ones and zeros) the message can basically be received instantly, and in just one message (movies have to be split into thousands of smaller messages to and from the server). The time it takes the message to physically reach your device is very very small to humans. Worst case it would take a second, normal case probably 100 milliseconds. Edit: look at edman007's answer to see why it is important that all apps on your phone share one connection to FCM. And how this helps the speed of a message being sent.",
"It's a very light package like a txt message being sent containing only the title. The app is already in your phone to put the notification presentation. Then you click the notification so it fetches the rest of the details.",
"There are two aspects to internet speed, latency and speed. Latency is is how long it actually takes data to get from one point (measured in milliseconds typically), speed is how much data can move in some period (measured in Mbps typically). Phones are typically high for both, when they are in a power save mode the transmitter powers down, and when you need to use the internet it can take a full second under 3G to switch to full speed, I think 4G is a little faster here, I'm not sure. Once connected, even via something like 3G, you could easily get 100kbps (considered very slow by today's standards), and the latency on this connection might be high, like 100ms. Now, Youtube is slow on that connection because a video might not play until 1MB has been downloaded, at 100kbps there is the startup latency (~1s) plus connection latency (typically get hit twice) for a total of 200ms, and then the time to download that 1MB (10.49s), so Youtube takes ~11.7s to load, very slow. A push connection is different, first it's already connected so you skip the connection latency, and just are hit with the response time which would be closer to 50ms. Second, it's typically little more than the worse you see on the screen, for 500bytes is reasonable. 500bytes at 100kbps takes 5ms to download. So if you're already using your phone and don't need to startup the transmitter it should take 55ms which is instant as far as you can tell, if you need to startup the transmitter then you might add a second, for a total of 1 second."
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7lalsg | Why do some programs hog resources, but the project file is only some kilobytes? | For example, Fl Studio, Premiere Pro, Photoshop | Technology | explainlikeimfive | {
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"> Why do some programs hog resources, but the project file is only some kilobytes? If I give you a shopping list which includes 300 items, how difficult is it to carry that list? Probably not difficult, you could list all that on a single sheet of paper. Now how hard is it to carry all the items on the list? Probably impossible! The project file just points at other files on the disk and the program needs to load those other files in order to work with them. That your project file or shopping list isn't very large is irrelevant.",
"Scenario 1: Imagine I give you a copy of War and Peace to read. You read it slowly, one page at a time, taking regular breaks to do other things. It takes you a while to read it, but you read it all. But during the time you were reading it, you were not so busy that you had no time to do anything else. Scenario 2: I give you the same copy of War and Peace, and ask you to read the first paragraph of chapter 5. It doesn't take very long. Because it doesn't take very long, you quickly finish the job and move on to other things. Scenario 3: I give you a scientific equation to study and understand. The equation is only one page long - much shorter than War and Peace. But it takes you a while to get your head around it. And during that time, you really don't want to be disturbed, because you don't want to lose your train of thought. You can't really do anything else until you've understood the equation. Conclusion - the amount of brain power it takes to do a task is not in any way related to the amount of data associated with the task. Your examples are like scenario 3 - not that much data, but the little data there is requires a *lot* of processing."
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7ld1wa | If we are trying to harness the wind and use it as a natural resource for electricity, then why are there windmill farms out there with a stopped windmill? Exceptions being maintenance or malfunction | Technology | explainlikeimfive | {
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"1) Maintenance, as you guessed. Stuff breaks down; if you visit a normal power plant you'll find a few of their turbines are off as well. 2) You'd think that more wind = better for a windmill, but there's a point where the wind becomes *too* strong, enough to damage the machinery. At that point they have to lock the windmill in place for its own safety. 3) Low demand. It's possible that the grid just didn't need that much power at the time you were driving by, so not all the turbines were active.",
"If *all* the windmills are feathered [turned off] it is likely that there is too much wind or that the wind is somehow bad for the mills. [Example: too gusty to be useful]. If *some* are feathered and some are active, it is likely that the operators are creating enough energy for current demand. If this is the case, turning all the windmills on would likely overload the system and cause damage to one or more spots in the wires or transformers."
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7lejz8 | How do headphones create a sense of something being behind/in front of you, when they only play sound to the left and right of your head? | Technology | explainlikeimfive | {
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"I want to elaborate on the other answers to explain how it actually works. Your ears aren't just two holes in your ear- they have flesh that is shaped differently in each direction. As sounds come to your ear through different directions, the shape of your outer ear alters the sound (making certain frequencies change in volume by the time they hit your inner ear). Your can (sort of) reproduce this in the studio by accentuating different frequencies and affects like reverb. But placing audio in front and behind is actually a lot harder to replicate than left and right. \"Far vs near\" and \"left vs right\" can be done easily - \"forward vs backwards\" and \"up vs down\" are a lot more ambiguous.",
"Think about it this way: to us, all sound only comes from the left and the right. Our ears are incapable of individually determining the source of a sound: that's not how sound works. However, together, they can get clues: if the sound is louder in one ear, its in that direction. Similar tricks can be used for other directions, but all of those can be duplicated with just two different sounds right at the ear",
"It's all computer simulated how our ears would hear things in nature too. Ever seen a 7.1 headset somewhere? Yep, all software. You don't have more speakers in those either way (only rarely in high end ones). Our ear is shaped in such a way that the sound hits the ear canal in a different way thus giving us the impression the sound would come from behind, it's trained on your own ear form. Our ears and a headset with only left and right \"channels\" can simulate that by making sounds that are behind you more echo-y, muffled a tiny bit and appearing further away. That tricks your brain into hearing \"3D\" with just 2 speakers."
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7lgr3b | Why does popular software like Spotify, Firefox or Google Chrome have very small (less than 1 megabyte) installer files when all they do is download larger amounts of data immediately after starting? | Technology | explainlikeimfive | {
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"When you develop a popular software, you'll constently improve features and correct bugs (much more demand than for an obscure release). As mainly your software will be distributed through various hosting sites (good to reach a wider audiance), if you release often a full package, you'll have to updates many sites. Having a download that would not change (he only download a file), mean that when you release a new version on your home server, you don't have to upadte any site, as the downloader will take the source from only one location.",
"The small installer can look at the current state of your machine and download just the parts that your machine needs and doesn't already have.",
"Basically, that tiny installer gets to be somewhat smart about what to install and how: * It can call the right places to check what the latest version of the software is and download that at install time. With an offline installer, you download and install a potentially out-of-date version, then go and download and update the new version just as with the smaller installer. This is a waste of resources. * The installer can be validate each file it's downloading and re-download only that if it detects errors, instead of just detecting that the whole offline installer is damaged and asking you to download the whole thing again. * It can download things more efficiently (for some definition thereof). For example, several of these installers for games use BitTorrent or similar systems to download from many sources at once. Alternatively, it can choose an appropriate mirror to download from, as it's both cheaper and faster to download stuff from servers geographically close to you (though this is less of a problem now that CDNs are in wide use) (EDIT: fix typos and bullets)"
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7lj3ej | Why do toilets use fresh, drinkable water instead of water from undeniable sources such as the ocean or lakes? | Technology | explainlikeimfive | {
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"Because it would require an entirely separate water supply network which we don't have. Additionally, salt water is much more corrosive than drinking water, so it will be harder to maintain.",
"Logistics Supplying drinking water ***and*** utility water to every household, business, etc would take twice the resources (plumbing, maintenance, etc) . While what you're suggesting makes a certain sense, it would just be so much more expensive to implement than the current system of \"everything in is good, everything out is bad\"",
"The biggest problem is that you'd need a whole means of getting non-treated water into the toilet - and it can't use the same pipes as regular water, or it'll contaminate it. So using clean water means that we only need one set of pipes going into every house, which is a plus. Many areas use what's called \"greywater\" for toilets - basically, any water coming from the sinks or showers, laundry machines, etc. It's not drinkable any more, but it's not going to spread disease. Instead of running into the sewer, some of the greywater will be used for toilet flushes, at which point it's considered blackwater and goes straight to sewers, waste processing, etc.",
"I’m not an expert, but I would guess that you would need to run a separate line from the other water source into each and every home, costing twice as much and using twice the resources for building pipelines just to flush a toilet. Edit: possibly using gray water, say from each home’s shower, would be a viable solution.",
"In some cities reclaimed water is on the rise. Wastewater is treated at the plant and some of it is pumped back to (mostly) commercial customers in a separate pipe network. The pipes are colored purple to distinguish them from drinking water. The reclaimed water is often used for toilet flushing and irrigation but can also be used for car washing etc. (ie. non-potable uses)."
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7lj76k | If I'm pulling 100 Mb/s why are my progress bars and % completion not jumping 100 Mb/s? | Technology | explainlikeimfive | {
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"text": [
"Just because your connection is capable of receiving 100mb/s doesn't mean the sender is sending 100mb/s. Internet traffic speeds depend on every network device between you and the sender that you share with millions of other users.",
"It is good to realize, that Internet traffic contains lots of framing. Data is split into small packages which have address and othe info, and then a piece of the data that is being sent. This increases the overall amount of data a lot. So even if you'd receive 100 Mb/s, a lot of that is just extra data used for delivering. Also, keep in mind that 100 Mb/s is 8 times less than 100 MB/s. Network speed is measured in bits, not Bytes. When considering the progress bars, if data would just be transferred, that would be the case. But there might be some extra processing for the data. How ever, I don't know the context of what you are asking."
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7lk6yo | Why do car windows get a grid pattern on them | So what I mean is, I’ve noticed on some rear windscreens what looks like squares of condensation in between the heating elements of the back window. Naturally I assumed it was because of those heating elements, however I also get in on my side windows too when I’ve had the heating on. What cause it | Technology | explainlikeimfive | {
"a_id": [
"drmyxik",
"drnauwp"
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"text": [
"Whenever the glass is rapidly cooled during the tempering process there are these air jets that blow cool air on the glass. This creates distortions in the glass that are almost invisible, until you put on polarized glasses. Different automakers have different (patented) patterns or cooling methods to reduce this distortion.",
"Tempered glass has stressors built-in. You can see them with polarized sunglasses. The built-in stress is what causes the window to completely shatter into small pieces when the window is damaged in any way. Even a scratch may cause enough damage to shatter the window."
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7lmc22 | How do the “I am not a robot” things on websites work? | Technology | explainlikeimfive | {
"a_id": [
"drncgvr",
"drnbark"
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"text": [
"Nice try, robot. You think we would just give you all our secrets?",
"the validation isn't you clicking the box. it's the path of your mouse cursor on the way to clicking the box. bots move the mouse in moves with a signature controlled by software and random number generators. humans don't."
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7lmui1 | When creating mashups of songs, how do the producers obtain the vocal samples? | Technology | explainlikeimfive | {
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"text": [
"If it is a fully licensed song; i.e one that all parties involved have agreed to create, then the editors will most likely be given the a copy of all the tracks involved in the song. This will include every instrument, in isolation. This makes it very easy to remix, and rematch, all the disparate parts together into a new, unique song."
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7lmvut | Can someone please explain why the SpaceX rocket looked more like an alien than a typical rocket launch? Also, why was there no sound? Why did it seem to be same size for people who viewed it from 100s if miles apart from each other? Never seen anything like it. | Technology | explainlikeimfive | {
"a_id": [
"drng54g"
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"text": [
"It was just after sunset, and the plume was very high up, so far up that if you were there you would still be able to see the sun( which had set on land but was still making way across pacific). It was very large and high up, so many people were able to see it."
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7lqh4j | How does the Recolor tool in an image editing program know what RGB to change each pixel to match the selected color? | Technology | explainlikeimfive | {
"a_id": [
"dro640r"
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"text": [
"From what I understand it usually uses the primary and secondary selected colors to determine which color is changed to what. There is also likely a sensitivity range which can be set to determine how close to the selected color it needs to be."
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7lql0y | How does the screen of your car know the name of the current playing song when you are just listening to the radio? | Technology | explainlikeimfive | {
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"text": [
"It's called RBDS. They just send the data along with the regular signal. Your radio gets the extra info and it tells you what song is playing. Edit: a word",
"Ever see Star Trek or some other show where they find \"a signal in the signal\"? It is just like that, the radio signal has all the info for sound and text included. But if you have a simple radio that only decodes the sound you may be left unaware of the signal in the signal (or more likely just a portion of the signal) that has the text.",
"So, FM stands for \"frequency modulation.\" The simple definition of \"modulation\" in this context is the ability to combine multiple signals into one. The transmission is modulated on one end, and then demodulated on the other end. This frequency modulation technology is what allowed FM broadcasts to be in stereo, putting FM at a huge advantage over AM. Starting 40 years ago, some really smart people developed a way to send small amounts of digital data modulated into an analog FM transmission, and from this technology, RDS/RBDS was born. In addition to the song name, it also transmits the radio call sign and other small pieces of information. I believe that in Europe, it can be used to alert drivers of an emergency vehicle approaching, but I'm not sure about that. Anyway, due to the limitations of this decades-old technology, it's pretty unreliable, which is why it's often glitchy, with garbled text from time to time. About 15 years ago, along came HD Radio, in which the *entire* signal is digital. The HD radio spec also allows more bandwidth, or space in the signal, for non-audio data. That's why newer HD radios, like those built into cars with integrated entertainment/navigation systems, can display album cover art in addition to the song title.",
"Not sure about commercial radio stations, but I worked at a public radio station and the DJ had to type in the song info manually."
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7lu1wr | How do wireless video game controllers work without lag when similar wireless devices have delay? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"You get latency from your screen refresh - up to 17ms minimum at 60fps. You get latency from rendering - if you have a frame buffer of 2, you're looking at 34ms extra latency. You get latency from processing. With a wired controller you would have latency from the USB controller, and the latency caused by the signal going up the wire. So a wireless controller vs wired controller, the input latency difference is really tiny. In fact, because the speed of signal over air is lower than over a cable, wireless can and sometimes is faster than wired. Additionally, compared to many wireless devices, the signal from game controllers is tiny. You get some latency from the size of a file being sent divided by the bandwidth. With a game controller, the bandwidth is orders of magnitude higher than the latency. If you have 16 buttons and 2 sticks with 2 axis of 32 bit accuracy, you are looking at 18 bytes of data. Bluetooth might have 3 MByte/s bandwidth, so you can poll 1000 times a second and still be using less than 1% of the bandwidth. A picture meanwhile might be 4 MB, which would have a transmission time of over a second over bluetooth.",
"Afaik, they usually do. The delay is really small and unless you play at a high level/a lot(like a lot lot) you will barely notice it at all. Feel free to correct me if I'm wrong"
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7lu2cn | Why does it take longer for a computer to recognise an incorrect password than a correct one? | Technology | explainlikeimfive | {
"a_id": [
"drozuya",
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"text": [
"It doesn't take longer: typically there's a deliberate delay programmed in. This delay slows down automatic password crackers that work by trial and error.",
"While there are automatic slowdown things to stop you repeatedly typing wrong passwords in according to a Microsoft Dev there's a reason URL_0 Basically if you put in the same password you used last time the computer's like \"this is fine\" and logs you on. But if you put in the wrong one first it needs to check on the network that you haven't changed it elsewhere in the meantime hence the delay."
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7luaea | how is laser eye surgery like LASIK achieved? What is the technology, how does it work, and how is the procedure executed? | Technology | explainlikeimfive | {
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"text": [
"Not sure how much you know about eye problems so will explain some stuff. Light reflects from your lens onto your retina... Action potentials, transduction and there you have an image. Light - cornea - bit of space - iris - lens - \"space\" - retina is the order. Myopia (short sightedness) is an issue where the eye muscles (ciliary muscles) are relatively tight and causes your lens to be relatively tight or fat, changing the \"normal\" shape of your eye. Causing light to not focus on the retina. LASIK would change the shape of the cornea instead of the lens. Mainly because your cornea isn't flat, kind of curved so will reflect light into the eye onto the retina. Also lens is hard to get to... More invasive. Laser is used to open up a flap on your cornea. Pretty much more lasers are used again to remove underlying tissue below your cornea (stroma), removing this tissue can cause light to be reflected onto the retina so it's \"normal\". Flap is closed, and perfect vision is ensured (hopefully).",
"Use a scalpel to cut the top off your eyeball and fold it back like the lid on a tin can. Use a laser to reshape the inner surface of the eyeball much like the curved face of a lens. Fold back the lid. Job done. Overpriced for the time it takes to do. And completely pointless if you are in near 40 as your you will need glasses within 5 years as your eyes are too old."
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7lucm4 | How do forensic investigators ensure that recovered computer files are accurate representations of the damaged or deleted file? | Technology | explainlikeimfive | {
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"In short: They can't. Either a file is on a hard drive (or other storage device) or it's not. When an investigator \"recovers\" a file, usually it just means that they found a file that's not indexed. On modern operating systems every file in the system is listed in an index called a *master file table* that tells the operating system where to physically look on the storage device for the file it wants. The operating system then creates a file structure hierarchy which is what you typically see on your system where everything is broken down into subfolders. When you delete a file in Windows and it goes in the recycling bin, then empty the recycling bin you haven't actually deleted that file. The operating system just marks that file as being *safe to overwrite* but if you have the right program and are quick enough you can recover or \"undelete\" these files before they are overwritten. You may recover a file that is partially overwritten in which case it will most likely appear as corrupted or damaged. Depending on the type of file you may still be able to open it or at least view the underlying code to determine the nature of it. When a file is overwritten partially it won't become cross contaminated with the new data being written as that data is protected by the master file table so the old file will only be losing data. In essence a forensic investigator can only present evidence for data they sufficiently have uncovered, and there's no real way to create something out of nothing when it comes to file recovery, the closest they could do is find a matching duplicate online for what they believe the undamaged file looks like but that will probably only work if the original file isn't very damaged to begin with."
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7lvdsf | How do Liquid Crystal Displays (LCDs) work? | Technology | explainlikeimfive | {
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"Basically, there is a backlight behind everything. Infront of the backlight are 3 layers of 'pixels', red, green and blue. Each pixel in each layer allows light (from the backlight) through when a electrical current is passed through (or in some cases, not passed through). These colours 'mix' and through the help of a polarising filter you get what you see on your monitor.",
"Let's look at light. Light can be thought of as a series of waves. Normally, the waves are moving at all sorts of angles. You can pass light through a *polarizing filter* which straightens out the light waves in one plane. It does this by blocking the some of the light and letting only some through. Sort of like having messy hair and then combing it straight. If you take 2 polarizing filters, but turn the second one 90 degrees, you can effectively block *all* the light. Got it? Ok. Years ago, smart researchers figured out a way to make a material polarize light when electricity was run through it. This was liquid crystal\" . Power off= no polarize. Power on: polarize. So, combine that material with a normal polarizing filter (turned 90 degrees!) and you have created an electric light blocker! So, now you have a way to block light. Take 3 very small versions of this (call them LCD pixels)... and put a red, green, and blue filter in front of them. When you put light behind it and turn off the power to the 3 pixels, the light from behind shines through and lights up all 3... producing red/green/blue light...which you see as white light. Now, power up the pixels. You can now block the light selectively. If you have enough of them (large LCD display) , and a way to control them (computer/electronics) you can create any image you want.",
"I'm going to talk about the plain gray/black LCD displays, like you'd see on an old-school digital watch or calculator. Liquid crystals only allow light to pass that is oriented in a particular direction, but that direction changes when electricity is applied to the crystals. On top of the crystals, there is a piece of glass that also only allows light with a particular orientation to pass through, but electricity doesn't change that direction. When the electricity is off, those two directions line up, so that light in that direction can pass through. But when the electricity is on, the two directions that can pass are far different from each other, so the light that can pass through the glass can't pass through the LCD, and vice versa, which means that the combination of the two of them is opaque. In practice, the crystals are contained in a substrate that keeps them in particular locations, each of which can be electrified individually. They have tiny, nearly invisible wires running to each of those locations to provide the electricity."
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Subsets and Splits